U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-286 521
DEVELOPMENT DOCUMENT FOR EFFLUENT LIMITATIONS GUIDELINES
FOR THE ORE MINING AND DRESSING POINT SOURCE CATEGORY,
VOLUME II
ENVIRONMENTAL PROTECTION AGENCY
APRIL 1978
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the
ORE MINING AND DRESSING
POINT SOURCE CATEGORY
VOLUME II - SECTIONS VII - XIV
Douglas M. Costle
Administrator
Thomas C. Jorling
Assistant Administrator for
Water and Hazardous Materials
Swep Davis
Deputy Assistant Administrator
for Water Planning and standards
Robert B. schaffer
Director, Effluent Guidelines Division
Baldwin M. Jarrett
Project Officer
Ronald G. Kirby
Assistant Project Officer
July, 1978
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20H60
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50J72-IQ1
REPORT DOCUMENTATION
PAGE
l._ REPORT NO.
EPA 440/1-78/061-e
4. Title and Subtitle
Development Document for Effluent Limitations Guidelines for
the Ore Mining and Dressing Point Source Category (Vol. II)
7. Author(s) Baldwin M. Jarrett, Project Officer
. Ronald G. Kirby. Assistant Project Officer^
9. Performing Organization Name and Address
Effluent Guidelines Division
Office of Water and Waste Management
U. S. Environmental Protection Agency
401 M Street, S. W.
Washington, D. C. 20460
12. Sponsoring Organization Name and Address
Same
3. Recipient's Accession No.
PB-286 521
5. Report Date
April 1978
6.
8. Performing Organization Rept. No.
10. Project/Task/Work Unit No.
2BB 156
11. Contract(C) or Grant(G) No.
(C)
(G)
13. Type of Report & Period Covered
Final Report
14.
EPA-EGD
15. Supplementary Notes
16. Abstract (Limit: 200 words)
This document presents the findings of an extensive study of the ore mining and
dressing industry, for the purpose of developing effluent limitations guidelines for
existing point sources and standards of performance and pretreatment standards for
new sources, to implement Sections 304, 306, and 307 of the Federal Water Pollution
Control Act, as amended in 1977 by the Clean Water Act, P.L. 95-217.
Effluent limitations guidelines are set forth for the degree of effluent reduction
attainable through the application of the best practicable control technology currently
available (BPCTCA) and the degree of effluent reduction attainable through the
application of the best available technology economically achievable (BATEA) which
must be achieved by existing point sources. The standards of performance for new
sources are set forth for the degree of effluent reduction which is achievable
through the application of the best available demonstrated control technology
processes, operating methods, or other alternatives.
Supporting data and rationale for development of the proposed effluent limitation
guidelines and standards of performance are contained in this report (Volumes I
and II).
17. Document Analysis a. Descriptors
Ore Mining
Mineral Dressing
Water Pollution Control
Waste Water Treatment
b. Identifiers/Open-Ended Terms
Best Available Technology
Economically Achievable
Best Practicable Control
Technology Currently Available
18. Availability Statement
Release to Public
19. Security Class (This Report)
Unclassified
20. Security Class (This Page)
Unclassified
21. No. of Pages
22. Price ,
PC A22/MF A01
(See ANSI-Z39.18)
See Instruct/on^ on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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ABSTRACT
This document presents the findings of an extensive study of
the ore mining and dressing industry, for the purpose of
developing effluent limitations guidelines for existing
point sources and standards of performance and pretreatment
standards for new sources, to implement Sections 304, 306
and 307 of the Federal Water Pollution Control Act, as
amended (33 U.S.C. 1551, 1311, and 1316, 86 Stat. 816 et.
seq.) (the "Act").
Effluent limitations guidelines contained herein set
the degree of effluent reduction attainable through the
application of the best practicable control technology
currently available (BPCTCA) and the degree of effluent
reduction attainable through the application of the best
available technology economically achievable (BATEA) which
must be achieved by existing point sources by July 1, 1977,
and July 1, 1983, respectively. The standards of
performance and pretreatment standards for new sources
contained herein set forth the degree of effluent reduction
which is achievable through the application of the best
available demonstrated control technology, processes,
operating methods, or other alternatives.
Based upon the application of the best practicable control
technology currently available, 13 of the 41 subcategories
for which separate limitations are suggested can be operated
with no discharge of process wastewater. With the best
available technology economically achievable, 21 of the 41
subcategories for which separate limitations are proposed
can be operated with no discharge of process wastewater to
navigable waters. No discharge of process wastewater
pollutants is also achievable as a new source performance
standard for 21 of the Ul subcategories.
Supporting data and rationale for development of the
proposed effluent limitation guidelines and standards of
performance are contained in this report (Volumes I and II) .
iii
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CONTENTS (VOLUME II)
Section £^2£
VII CONTROL AND TREATMENT TECHNOLOGY 409
INTRODUCTION 409
CONTROL PRACTICES AND TECHNOLOGY 410
TREATMENT TECHNOLOGY u26
EXEMPLARY TREATMENT OPERATIONS BY ORE
CATEGORY 469
VIII COST, ENERGY, AND NONWATER-QUALITY ASPECTS 582
INTRODUCTION 582
SUMMARY OF METHODS USED 583
WASTEWATER-TREATMENT COSTS FOR IRON-ORE
CATEGORY 589
WASTEWATER TREATMENT COSTS FOR COPPER-ORE
CATEGORY 596
WASTEWATER-TREATMENT COSTS FOR LEAD- AND
ZINC-ORE CATEGORY 603
WASTEWATER-TREATMENT COSTS FOR GOLD-ORE
CATEGORY 61"
WASTEWATER-TREATMENT COSTS FOR SILVER-ORE
CATEGORY 636
WASTEWATER-TREATMENT COSTS FOR BAUXITE
CATEGORY 6U6
WASTEWATER-TREATMENT COSTS FOR FERROALLOY-
ORE CATEGORY 65°
WASTEWATER TREATMENT COSTS FOR MERCURY-
ORE CATEGORY 674
WASTEWATER TREATMENT COSTS FOR URANIUM-
ORE CATEGORY 68°
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WASTEWATER TREATMENT COSTS FOR METAL
ORES, NOT ELSEHWERE CLASSIFIED 704
NON-WATER QUALITY ASPECTS 718
IX BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE, GUIDELINES AND LIMITATIONS 723
INTRODUCTION 723
GENERAL WATER GUIDELINES 725
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE BY ORE CATEGORY
AND SUBCATEGORY 727
X BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE, GUIDELINES AND LIMITATIONS 785
INTRODUCTION 785
GENERAL WATER GUIDELINES 786
BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE BY ORE CATEGORY AND SUBCATEGORY 788
XI NEW SOURCE PERFORMANCE STANDARDS AND
PRETREATMENT STANDARDS 819
INTRODUCTION 819
GENERAL WATER GUIDELINES 820
NEW SOURCE STANDARDS BY ORE CATEGORY 820
PRETREATMENT STANDARDS 828
XII ACKNOWLEDGMENTS 833
XIII REFERENCES 835
XIV GLOSSARY 843
XV BIBLIOGRAPHY 869
LIST OF CHEMICAL SYMBOLS
CONVERSION TABLE
vi
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CONTENTS (VOLUME I)
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 3
III INTRODUCTION 11
PURPOSE ANE AUTHORITY 11
SUMMARY OF METHODS USED FOR DEVELOPMENT
OF EFFLUENT LIMITATION GUIDELINES AND
STANDARDS OF TECHNOLOGY 13
SUMMARY OF ORE-BENEFICIATION PROCESSES 17
GENERAL DESCRIPTION OF INDUSTRY BY ORE
CATEGORY 2 9
IV INDUSTRY CATEGORIZATION 145
INTRODUCTION 145
FACTORS INFLUENCING SELECTION OF
SUBCATEGORIES IN ALL METAL ORE CATEGORIES 147
DISCUSSION OF PRIMARY FACTORS INFLUENCING
SUBCATEGORIZATION BY ORE CATEGORY 153
SUMMARY OF RECOMMENDED SUECATEGORIZATION 174
FINAL SUBCATEGORIZATION 174
V WASTE CHARACTERIZATION 179
INTRODUCTION 179
SPECIFIC WATER USES IN ALL CATEGORIES 181
PROCESS WASTE CHARACTERISTICS BY ORE
CATEGORY 183
VI SELECTION OF POLLUTANT PARAMETERS 379
INTRODUCTION 379
GUIDELINE PARAMETER-SELECTION CRITERIA 37c?
vii
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SIGNIFICANCE AND RATIONALE FOR SELECTION
OF POLLUTION PARAMETERS 380
SIGNIFICANCE AND RATIONALE FOR REJECTION
OF POLLUTION PARAMETERS 405
SUMMARY OF POLLUTION PARAMETERS SELECTED
BY CATEGORY 407
viii
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NO-
VII-1 Use of Barium Salts for Removal of Radium
from Wastewater 116
VII-2 Properties of Ion Exchangers for Metallurgical
Applications 155
VII-3 Analytical Data for Modified Desal Process «59
VII-4 Rejection of Metal Salts by Reverse-Osmosis
Membranes 16 2
VII-5 Chemical Characteristics of Settling-Pond Dis-
charge at Mine 1105 170
VII-6 Chemical Compositions of Raw and Treated Waste-
loading at Mine/Mill 1109 172
VTI-7 Concentration of Parameters Present in Raw
Wastewater and Effluent Following Lime
Precipitation at Mine 2120B 178
VII-8 Concentration of Parameters Present in Raw Waste-
water and Effluent Following Lime Precipita-
tion at Mine 2120C 179
VII-9 Dump, Heap, and In-Situ Leach-Solution Control
and Treatment Practice (1973) 180
VTI-10 Solution-Control Practice in Vat Leaching of
Copper Ore 182
VII-11 Reduction of Pollutants in Concentrator Tails
by Settling at Various pH Levels 187
VII-12 Efficiency of Coagulation Treatment to Reduce
Pollutant Loads in Combined Waste (Includ-
ing Mill Waste) Prior to Discharge (Pilot
Plant — Mill 2122, November 197U) 189
VII-13 Chemical compositions of Raw and Treated Mine-
waters from Mine 3105 (Historical Data Pre-
sented for Comparison) 190
VII-14 Chemical Compositions of Raw and Treated Mine
Water from Mine 3101 193
VII-15 Chemical Characteristics of Raw and Treated
Mine Water for New Brunswick, Canada,
Copper/Lead/Zinc Pilot-Plant Operation 19U
VII-16 Chemical Composition and Waste Load of Treated
Mill Wastewater at Mill 3103 197
VII-17 Chemical Composition and Waste Loading for Raw
and Treated Mill Wastewater from Mill 3102 500
VII-18 Chemical Composition of Mill Wastewater for
Mill 3108 505
VII-19 Characteristics of Raw and Treated Wastewater
at Selected Placer Mining Operations 507
ix
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TABLES
No. Title page
VII-20 Waste Compositions and Raw and Treated Waste Loads
Achieved at Mill 4102 by Tailing-Pond Treat-
ment 510
VII-21 Chemical Compositions of Mill Wastewater and
Tailing-Pond Decant Water at Mill 4101 (No
Resultant Discharge) 512
VII-22 Waste Compositions and Raw and Treated Waste
Loads at Mill 4401 (Using Tailing-Pond
Treatment and Partial Recycle) 520
VII-23 Chemical Compositions of Mill Raw Wastewater
and Tailing-Pond Decant Water at Mill 4402 523
VII-24 Chemical compositions of Raw and Treated Mine
Waters at Mine 5101 526
VII-25 Chemical Compositions of Raw and Treated Mine
Waters at Mine 5102 528
VII-26 Chemical Compositions of Raw ft.ne Wastewater
and Treated Effluent at Mine 6103 531
VII-27 Chemical Compositions of Raw and Treated Mine
Waters at Mine 6104 (Clariflocculator
Treatment) 532
VII-28 Chemical Compositions of Raw and Treated Waste-
waters at Mine 6107 533
VII-29 Analyses of Intake and Discharge waters From Mill
6101 (Company Data) 536
VII-30 Chemical Composition of Wastewater and Waste
Loading for Mill 6101 537
VII-31 Chemical Composition and Calculated Waste Load for
Mill 6102 Tailing-Pond surface water, with
Analytical Data for Mill-Reservoir Water 541
VII-32 Chemical Composition and Waste Loading for Discharge
at Mill 6102 (Company Data) 541
VII-33 Chemical Composition and Treated Waste Loads for
Overflow from First Settling Pond at Mill 6106 544
VII-34 Characteristics of Surface Water from Second Settling
Pond at Mill 6106 544
VII-35 Chemical Composition and Treated Waste Loads from
Final Effluent for Mine/Mill 6106 During
Rainy Season (Company Cata) 545
VII-36 Chemical Composition and Waste Loading from Area
Runoff and Reclamation-Pond seepage at Mill
6107 (Company Data) 545
VII-37 Chemical Composition and waste Loading for Cooling-
Water Effluent at Mill 6107 (Company Data) 547
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TABLES
Title paq<
VII-38 Chemical Composition and Waste Loading for Process
Effluent After Ammonia Treatment at Mill 6107 548
VIl-39 Chemical Composition and Waste Loading for Drier
Scrubber Bleed Water After Settling Treatment
at Mill 6107 549
VII-40 Chemical Composition and Waste Loading for Holding-
Pond Effluent (Process Water and Drier Scrubber
Bleed) 55T
VII-41 Chemical Composition and Waste Loading for Roaster
Scrubber Bleed Water After Settling at Mill
6107 552
VII-42 Chemical Composition and Waste Loading for Roaster
Scrubber Bleed Water After Settling at Mill
6107 (Company Data) 553
VII-43 Chemical Composition and Waste Loading for Average
Total Process Effluent at Mill 6107 (Company
Data) 554
VII-44 Chemical Compositions of Mill Wastewater and
Tailing-Pond Surface Water After Treatment
at Mine/Mill 9201 (No Discharge, Recycle of
Treated Water) 557
VII-45 Characterization of Mill Wastewater and Tailing-Pond
Surface Water Following settling at Mine/
Mill 9202 559
VII-46 Chemical Compositions of Raw and Treated
Wastewaters at Mine 9402 (001) 562
VII-47 Chemical Compositions of Raw and Treated
Wastewaters at Mine 9402 (002) 563
VII-48 Chemical Compositions of Raw and Treated Waste-
waters and Effluent Waste Loading at Mill 9403
(Settling and BaC12_ Coprecipitation) 567
VII-49 Chemical Composition of Treated Effluent and
Waste Load from Mine/Mill 9904 (Platinum) 571
VII-50 Chemical Compositions of Raw Wastewater and Treated
Recycle Water at Mill 9903 (No Discharge) 571
VII-51 Chemical Compositions of Raw Wastewater and
Treated Recycle Water at Mill 9905 573
VII-52 Chemical Compositions of Raw and Treated
Wastewaters at Mill 9906 575
VII-53 Chemical Compositions of Raw and Treated
Wastewaters at Mill 9907 576
Vll-54 Wastewater Composition and Treated Waste Load
With Acid Flocculation and Settling at
Mill 9906 577
xi
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TABLES
No. Title page
VII-55 Wastewater Composition and Treated Waste Load
With Acid Flocculation and Settling at
Mill 9907 578
VII-56 Effluent Concentrations Achieved at Mines
Employing Treatment Technology 579
VII-57 Effluent Concentrations Achieved at Mills
Employing Treatment Technology 57^
VTII-1 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Iron) 589
VIII-2 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Iron) 593
VIII-3 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Copper) 597
VIII-4 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Copper) 600
VIII-5 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Lead/Zinc, No Solubility 604
VIII-6 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Lead/Zinc, Solubility 607
VIII-7 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical)—Lead/Zinc 612
VIII-8 water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Gold 616
VIII-9 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Gold) 620
VIII-10 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Gold) 624
VIII-11 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Gold) 629
VIII-12 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine/Mill (Hypothetical)—Gold/Gravity 633
xii
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TABLES
No. Title paq<
VIII-13 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Silver 638
VIII-14 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Silver) 643
VIII-15 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Bauxite) 648
VIII-16 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Ferroalloy 651
VIII-17 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical)—Ferroalloy/Limited 654
VTII-18 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical) 658
Vlll-19 Water Effluent Treatment costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical)—Ferroalloy/Flotation 661
VIII-20 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical)—Ferroalloy/Leaching 669
VIII-21 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Mercury 676
Vlli-22 Water Effluent Treatment costs and Resulting
Waste-Load Characteristics for Typical
Mill (Mercury) 680
Vlll-23 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Mercury) 685
VIII-2U Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Uranium 687
VIII-25 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mill (Hypothetical) — Uranium 697
VIII-26 Comparison of Model Mill Total Effluent-
Treatment Costs 703
VIII-27 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Typical
Mine (Hypothetical)—Antimony 705
xiii
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TABLES
No. Title Page
VIII-28 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Mine 9905 709
VTII-29 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Mill 9905 712
VIII-30 Water Effluent Treatment Costs and Resulting
Waste-Load Characteristics for Mine/Mill 9904 715
VIII-31 Principal Dry Solid Wastes Generated by
Selected Ore Categories in 1974 721
IX-1 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Iron-Ore Mines 729
IX-2 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Iron-Ore Mills
Employing Physical Methods and Chemical
Separation and Only Physical Separation 731
IX-3 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Copper Mines 733
IX-4 Parameters selected and Effluent Limitations
Recommended for BPCTCA—Copper Mills Using
Froth Flotation 735
IX-5 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Lead and Zinc
Mines 737
IX-6 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Lead and/or Zinc Mills 739
IX-7 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Gold Mines 740
IX-8 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Gold Mills Using
Amalgamation Process 7U3
IX-9 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Gold Mills Using
Flotation Process 744
IX-10 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Gold Mines or Mills
Using Gravity-Separation Methods 746
IX-11 Parameters selected and Effluent Limitations
Recommended for BPCTCA—Silver Mines (Alone) 748
IX-12 Parameters Selected and Effluent Limitations
Recommended for BPCTCA — Silver Mills
Using Froth Flotation Process 749
IX-13 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Silver Mills Using
Amalgamation Process 751
xiv
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TABLES
Title Page
Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Silver Mills Using
Gravity Separation 753
IX-15 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Bauxite Mines (Acid
or Alkaline Mine Drainage) 755
IX-16 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Ferroalloy-Ore Mines
Producing Greater Than 5,000 Metric Tons
(5,512 Short Tons) Per Year 757
IX-17 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Ferroalloy-Ore Mines
and Mills Processing Less Than 5,000 Metric
Tons (5,512 Short Tons) Per Year 759
IX-18 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Ferroalloy-Ore Mills
Processing More Than 5,000 Metric Tons (5,512
Short Tons) Per Year by Physical Processing 761
IX-19 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Ferroalloy-Ore Mills
Using Flotation Process 763
IX-20 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Ferroalloy-Ore Mills
Using Leaching Process 765
IX-21 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Mercury Mines 767
IX-22 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Uranium Mines 770
IX-23 Parameters Selected and Effluent Limitations
Recommended for BPCTCA — Uranium Mills 772
IX-24 Parameters selected and Effluent Limitations
Recommended for BPCTCA--Antimony Mines 774
IX-25 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Platinum Mines and
Mills Using Gravity Separation Methods 777
IX-26 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Titanium Mines 780
IX-27 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Titanium Mills 781
IX-28 Parameters Selected and Effluent Limitations
Recommended for BPCTCA—Titanium Dredge Mine
With Wet Separation Mill 783
X-l Parameters Selected and Effluent Limitations
Recommended for BATEA—Iron-Ore Mines 789
xv
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TABLES
NO. Title
X-2 Parameters Selected and Effluent Limitations
Recommended for BATEA—Iron-Ore Mills Employing
Physical Methods and Chemical Separation
and Only Employing Physical Separation 791
X-3 Parameters selected and Effluent Limitations
Recommended for BATEA—Copper Mines 793
X-4 Parameters Selected and Effluent Limitations
Recommended for BATEA—Lead and Zinc Mines 795
X-5 Parameters Selected and Effluent Limitations
Recommended for BATEA—Gold Mines 797
X-6 Parameters selected and Effluent Limitations
Recommended for BATEA—Silver Mines (Alone) 800
X-7 Parameters selected and Effluent Limitations
Recommended for BATEA—Bauxite Mines (Acid
or Alkaline Mine Drainage) 803
X-8 Parameters Selected and Effluent Limitations
Recommended for BATEA—-Ferroalloy-Ore Mines
Producing Greater Than 5,000 Metric Tons
(5,512 Short Tons) Per Year 805
X-9 Parameters selected and Effluent Limitations
Recommended for BATEA—Ferroalloy-Ore Mills
Processing More Than 5,000 Metric Tons (5,512
Short Tons) Per Year by Physical Processing 806
X-10 Parameters Selected and Effluent Limitations
Recommended for BATEA—Ferroalloy-Ore Mills
Using Flotation Process 809
X-ll Parameters Selected and Effluent Limitations
Recommended for BATEA—Ferroalloy-Ore Mills
Using Leaching Process 811
X-12 Parameters Selected and Effluent Limitations
Recommended for BATEA — Mercury Mines 812
X-13 Parameters Selected and Effluent Limitations
Recommended for BATEA—Uranium Mines 81U
XI-1 Parameters selected and Effluent Limitations
Recommended for NSPS—Ferroalloy-Ore Mines
Producing More Than 5,000 Metric Tons
(5,512 Short Tons) Per Year 823
XI-2 Parameters Selected and Effluent Limitations
Recommended for NSPS-Ferroalloy-Ore Mills
Processing More than 5,000 Metric Tons
(5,512 Short Tons) Per Year by Physical
Processing Methods 82U
XI-3 Parameters Selected and Effluent Limitations
Recommended for NSPS—Ferroalloy-Ore Mills
Using Flotation Process 826
XI-1 Parameters Selected and Effluent Limitations
Recommended for NSPS—Cranium Mines 827
xvi
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FIGURES
No. Title Page
VII-1 Lime Neutralization and Precipitation Process for
Treatment of Mine Water Prior to Discharge 437
VII-2 The Relationship of Solubilities of Metal
Ions as a Function of pH 439
VII-3 Minimum pH Value for complete Precipitation
of Metal Ions as Hydroxides 440
VII-4 Heavy-Metal Precipitation vs pH for Tailing-Pond
Effluent pH Adjustments by Lime Addition 141
VII-5 Diagram of Modified Desal Process 458
VII-6 Mill 1105 Water-Use System (Zero Discharge) 473
VII-7 Control of Effluent by Reuse of Mine Water in
Leaching (Mine 2122) 475
VII-8 Control of Mine-Water Effluent by Reuse in the
Concentrator (Mine/Mill 2119) 476
VII-9 control of Effluent Through Reuse of Mill Flotation-
Process Water in Other Facilities
(Mine/Mill 2124) 483
VII-10 Reduction in Waste Pollutant Load in Discharge
by Separation of Minewater From Tailing Pond
for Separate Treatment (Mill 2121) 484
VII-11 Schematic Diagram of Water Flows and Treatment
Facilities at Mill 3103 496
VII-12 Schematic Diagram of Water Flow and Treatment
Facilities at Mill 3102 (Tailing Pond/Stilling
Pond/Biological Treatment/Polishing Pond) 499
VII-13 Schematic Diagram of water Flow and Treatment
Facilities at Mill 3105 501
VII-14 Schematic Diagram of Treatment Facilities at
Mill 3101 503
VII-15 schematic Diagram of water Flow and Treatment
Facilities at Mine/Mill 3108 504
VII-16 Lime-Neutralization Plant for Open-Pit Mine 5102 525
VII-17 Water-Flow schematic Diagram for Mill 6102 539
VII-18 Ion Exchange for Mercury and Uranium at Low
Loadings and Concentrations 562
VII-19 chemical Changes in a Sequence of Tailing
Impoundments at Mill 9402 565
xvii
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
INTRODUCTION
Waterborne wastes from the mining of metal-ore minerals
consist primarily of suspended solids and metals in
solution. The mineralogy of the ore and associated
overburden and the chemical character of percolating mine
waters influence the metal content of mine wastewater, while
solids suspended in the wastewater are influenced by the
methods of mining as well as the physical nature and general
geologic characteristics of the ore.
The wastewater from ore milling and beneficiation operations
is characterized by high suspended-solid loads, heavy metals
in solution, dissolved solids, and process reagents added
during the concentration process. Impoundment and settling
pond facilities with lime addition for pH control or to
obtain improved settling characteristics primarily for
suspended solids removal, are in widespread use in the
treatment of mill effluents. This treatment technology is
effective in removal of other wastewater components as well.
Space requirements and location often affect the utilization
of this widespread treatment technology and dictate the
economics of the operations. Other treatment technologies
for removal of dissolved components are, for the most part,
well-known but are not in widespread use throughout the
industry.
The control and treatment of the waterborne wastes found in
the mining and beneficiation of metal-ore minerals are
influenced by several factors:
(1) Large volumes of mine water and wastewater from
ore-concentrating operations to be controlled and
treated.
(2) Seasonal, as well as daily, variations in the
amount and chemical characteristics of mine water
influenced by precipitation, runoff, and
underground-water contributions.
409
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(3) Differences in wastewater composition and
treatability caused by ore mineralogy and
processing techniques and reagents.
<<») Geographic location and climatic conditions.
(Treatment and control technology selection and
economics are influenced by the amount of water to
be handled.)
CONTROL PRACTICES AND TECHNOLOGY
Control technology, as discussed in this report, includes
techniques and practices which may be employed before,
during, and after the actual mining or milling operation to
reduce or eliminate adverse environmental effects resulting
from the discharge of mine or mill wastewater. Effective
pollution-control planning can reduce pollutant
contributions from active mining and milling sites and can
also minimize post-operational pollution potential. Because
pollution potential may not cease with closure of a mine or
mill, control measures also refer to methods practiced after
an operation has terminated production of ore or
concentrated product. The presence of pits, storage areas
for spoil (non-ore material, or waste), tailing ponds,
disturbed areas, and other results or effects of mining or
milling operations necessitates integrated plans for
reclamation, stabilization, and control to return the
affected areas to a condition at least fully capable of
supporting the uses which it was capable of supporting prior
to any mining and to achieve a stability not posing any
threat of water diminution, or pollution and to minimize
potential hazards associated with closed operations.
Mining Techniques
Mining techniques can effectively reduce amounts of
pollutants coming from a mine area by containment within the
mine area or by reducing their formation. These techniques
can be combined with careful reclamation planning and
implementation to provide maximum at-source pollution
control.
Pollution-control technology in underground mining is
largely restricted to at-source methods of reducing water
influx into mine workings and segregation of mine water from
working areas. Infiltration from strata surrounding the
workings is the primary source of water, and this water
reacts with air and sulfide minerals within the mines to
create acid, pH conditions and, thus, to increase the
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potential for solubilization of metals. Underground mines
are, therefore, faced with problems of water handling and
mine-drainage treatment. Open-pit mines, on the other hand,
receive both direct rainfall and runoff contributions, as
well as infiltrated water from intercepted strata.
Infiltration in underground mines generally results from
rainfall recharge of a ground-water reservoir. Rock
fracture zones, joints, and faults have a strong influence
on ground-water flow patterns since they can collect and
convey large volumes of water. These zones and faults can
intersect any portion of an underground mine and permit easy
access of ground water. In some mines, infiltration can
result in huge volumes of water that must be handled and
treated. Pumping can be a major part of the mining
operation in terms of equipment and expense—particularly,
in mines which do not discharge by gravity.
Water-infiltration control techniques, designed to reduce
the amount of water entering the workings, are extremely
important in underground mines located in or adjacent to
water-bearing strata. These techniques are often employed
in such mines to decrease the volume cf water requiring
handling and treatment, to make the mine workable, and to
control energy costs associated with dewatering. The
techniques include pressure grouting of fissures which are
entry points for water into the mine. New polymer-based
grouting materials have been developed which should improve
the effectiveness of such grouting procedures. In severe
cases, pilot holes can be drilled ahead of actual mining
areas to determine if excessive water is likely to be
encountered. when water is encountered, a small pilot hole
can be easily filled by pressure grouting, and mining
activity may be directed toward non-water-contributing areas
in the formation. The feasibility of such control is a
function of the structure of the ore body, the type of
surrounding rock, and the characteristics of ground water in
the area.
Decreased water volume, however, does not necessarily mean
that wastewater pollutant loading will also -decrease. In
underground mines, oxygen, in the presence of humidity,
interacts with'minerals on the mine walls and floor to
permit pollutant formation e.g., acid mine water, while
water flowing through the mine transports pollutants to the
outside. If the volume of this water is decreased but the
volume of pollutants remains unchanged, the resultant
smaller discharge will contain increased pollutant
concentrations, but approximately the same pollutant load.
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Rapid pumpout of the mine can, however, reduce the contact
time and significantly reduce the formation of pollutants.
Reduction of mine discharge volume can reduce water handling
costs. In cases of acid mine drainage, for example, the
same amounts of neutralizing agents will be required because
pollutant loads will remain unchanged. The volume of mine
water to be treated, however, will be reduced significantly,
together with the size of the necessary treatment and
settling facilities. This cost reduction, along with cost
savings which can be attributed to decreased pumping volumes
(hence, smaller pumps, lower energy requirements, and
sraller treatment facilities), makes use of water
infiltration-control techniques highly desirable.
Water entering underground mines may pass vertically through
the mine roof from rock formation above. These rock units
may have well-developed joint systems (fractures along which
no movement occurs), which tend to facilitate vertical flow.
Roof collapses can also cause widespread fracturing in over-
lying rocks, as well as joint separation far above the mine
roof. Opened joints may channel flow from overlying
aquifers (water-bearing rocks) a flooded mine above, or
even from the surface.
Fracturing of overlying strata is reduced by employing any
or all of several methods: (1) Increasing pillar size; (2)
Increasing support of the roof; (3) Limiting the number of
mine entries and reducing mine entry widths; (4) Backfilling
of the mined areas with waste material.
Surface mines are often responsible for collecting and
conveying large quantities of surface water to adjacent or
underlying underground mines. Ungraded surface mines often
collect water in open pits when no surface discharge point'
is available. That water may subsequently enter the ground-
water system and then percolate into an underground mine.
The influx of water to underground mines from either active
or abandoned surface mines can be significantly reduced
through implementation of a well-designed reclamation plan.
The only actual underground mining technique developed
specifically for pollution control is preplanned flooding.
This technique is primarily one of mine design, in which a
mine is planned from its inception for post-operation
flooding or zero discharge. In drift mines and shallow
slope or shaft mines, this is generally achieved by working
the mine with the dip of the rocx (inclination of the rock
to the horizontal) and pumping out the water which collects
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in the shafts. Upon completion of mining activities, the
mine is allowed to flood naturally, eliminating the
possibility of acid formation caused by the contact between
sulfide minerals and oxygen. Discharges, if any, from a
flooded mine should contain a much lower pollutant
concentration. A flooded mine may also be sealed.
Surface-Kater Control
Surface water control is an integral part of any mining
operation, either surface or underground. Surface water
interfers with operations in working areas and this must be
diverted from the site or removal by other means will be
necessary resulting in some cost. Surface water control to
benefit the mining operation will also result in pollution
control by preventing runoff from coming into contact with
disturbed areas.
Prior planning for waste disposal is also required to
control pollution from runoff. Disposal sites should be
isolated from surface flows and impoundments to prevent or
minimize pollution potential. In addition, several
techniques are practiced to prevent water pollution:
(1) Construction of a clay or other type of liner
beneath the planned waste disposal area to prevent
infiltration of surface water (precipitation) or
water contained in the waste into the ground-water
system.
(2) Compaction of waste material' to reduce
infiltration.
(3) Maintenance of uniformly sized refuse to enhance
good compaction (which may require additional
crushing).
(U) construction of a clay liner over the material to
minimize infiltration. This is usually succeeded
by placement of topsoil and seeding to establish a
vegetative cover for erosion protection and runoff
control.
(5) Excavation of diversion ditches surrounding the
refuse disposal site to exclude surface runoff from
the area. These ditches can also be used to
collect seepage from refuse piles, with subsequent
treatment, if necessary.
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Surface runoff in the-, immediate area of beneficiation
facilities presents another potential pollution problem.
Runoff from haul roads, areas near conveyors, and ore
storage piles is a potential source of pollutant loading to
nearby surface waters. Several current industry practices
to control this pollution are:
(1) Construction of ditches surrounding storage areas
to divert surface runoff and collect seepage that
does occur.
(2) Establishment of a vegetative cover of grasses in
areas of potential sheet wash and erosion to
stabilize the material, to control erosion and
sedimentation, and to improve the aesthetic aspects
of the area.
(3) Installation of hard surfaces on haul roads,
beneath conveyors, etc., with proper slopes to
direct drainage to a sump. Collected waters may be
pumped to an existing treatment facility for
treatment.
Another potential problem associated with construction of
tailing-pond treatment systems is the use of existing
valleys and natural drainage areas for impoundment of mine
water or mill process wastewater. The capacity of these
impoundment systems frequently is not large enough to
prevent high discharge flow rates—particularly, during the
late winter and early spring months. The use of ditches,
flumes, pipes, trench drains, and dikes will assist in
preventing runoff caused by snowmelt, rainfall, or streams
from entering impoundments. Very often, this runoff flow is
the only factor preventing attainment of zero discharge.
Diversion of natural runoff froir impoundment treatment
systems, or construction of these facilities in locations
which do not obstruct natural drainage, is therefore,
desirable.
Ditches may be constructed upslope from the impoundment to
prevent water from entering it. These ditches also convey
water away and reduce the total volume of water which must
be treated. This may result in decreased treatment costs,
which could offset the costs of diversion.
Segregation or Combination of Mine and Mill Wastewater
A widely adopted control practice in the ore mining and
dressing industry is the use of mine water as a source of
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process water. In many areas, this is a highly desirable
practice, because it serves as a water-conservation measure.
Waste constituents may thus be concentrated into one waste
stream for treatment. In other cases, however, this
practice results in the necessity for discharge from a mill-
water impoundment system because, even with recycle of part
of the process water, a net positive water balance results.
At several sites visited as part of this study, degradation
of the mine water quality is caused by combining the waste-
water streams for treatment at one location. A negative
effect results because water with low pollutant loading
serves to dilute water of higher pollutant loading. This
often results in decreased water-treatment efficiency
because concentrated waste streams can often be treated more
effectively than dilute waste streams. The mine water in
these cases may be treated by relatively simple methods;
while the volume of wastewater treated in the mill
impoundment system will be reduced, this water will be
treated with increased efficiency.
There are also locations where the use of mine water as
process water has resulted in an improvement in the ultimate
effluent. Choice of the options to segregate or combine
wastewater treatment for mines and mills must be made on an
individual basis, taking into account the character of the
wastewater to be treated (at both the mine and the mill),
the water balance in the mine/mill system, local climate,
and topography. The ability of a particular operation to
meet zero or reduced effluent levels may be dependent upon
this decision at each location.
Regradinq
Surface mining may often require removal of large amounts of
overburden to expose the ores to be exploited. Regrading
involves mass movement of material following ore extraction
to achieve a more desirable land configuration. Reasons for
regrading strip mined land are:
(1) aesthetic improvement of land surface
(2) returning usefulness to land
(3) providing a suitable base for revegetation
(U) burying pollution-forming materials,
e.g., heavy metals
(5) reducing erosion and subsequent sedimentation
(6) eliminating landsliding
(7) encouraging natural drainage
(8) eliminating ponding
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(9) eliminating hazards such as high cliffs
and deep pits
(10) controlling water pollution
Contour regrading is currently the required reclamation
technique for many of the nations's active contour and area
surface mines. This technique involves regrading a mine to
approximate original land contour. it is generally one of
the most favored and aesthetically pleasing regrading tech-
niques because the land is returned to its approximate pre-
mined state. This technique is also favored because nearly
all spoil is placed back in the pit, eliminating
oversteepened downslope spoil banks and reducing the size of
erodable reclaimed area. Contour regrading facilitates deep
burial of pollution-forming materials and minimizes contact
time between regraded spoil and surface runoff, thereby
reducing erosion and pollution formation.
However, there are also several disadvantages to contour
regrading that must be considered. in area and contour
stripping, there may be other forms of reclamation that
provide land configurations and slopes better suited to the
intended uses of the land. This can be particularly true
with steepslope contour strips, where large, high walls and
steep final spoil slopes limit application of contour
regrading. Mining is, therefore, frequently prohibited in
such areas, although there may be other regrading techniques
that could be effectively utilized. in addition, where
extremely thick ore bodies are mined beneath shallow
overburden, there may not be sufficient spoil material
remaining to return the land to the original contour.
There are several other reclamation techniques of varying
effectiveness which have been utilized in both active and
abandoned mines. These techniques include terrace, swale,
swallow-tail, and Georgia V-ditch, several of which are
quite similar in nature. In employing these techniques, the
upper high-wall portion is frequently left exposed or
backfilled at a steep angle, with the spoil outslope
remaining somewhat steeper than the original contour. In
all cases, a terrace of some form remains where the original
bench was located, and there are provisions for rapidly
channeling runoff from the spoil area. Such terraces may
permit more effective utilization of surface-mined land in
many cases.
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Disposal of excess spoil material is frequently a problem
where contour backfilling is not practiced. However, the
same problem can also occur, although less commonly, where
contour regrading is in use. Some types of overburden rock-
particularly, tightly packed sandstones—substantially
expand in volume when they are blasted and moved. As a
result, there may be a large volume of spoil material that
cannot be returned to the pit area, even when contour
backfilling is employed. To solve this problem, head-of-
hollow fill has been used for overburden storage. The extra
overburden is placed in narrow, steep-sided hollows in
compacted layers 1.2 to 2.4 meters (4 to 8 feet) thick and
graded to control surface drainage.
In this regrading and spoil storage technique, natural
ground is cleared of woody vegetation, and rock drains are
constructed where natural drains exist, except in areas
where inundation has occurred. This permits ground water
and natural percolation to leave fill areas without
saturating the fill, thereby reducing potential landslide
and erosion problems. Normally, the face of the fill is
terrace graded to minimize erosion of the steep outslope
area.
This technique of fill or spoil material deposition has been
limited to relatively narrow, steep-sided ravines that can
be adequately filled and graded. Design considerations
include the total number of acres in the watershed above a
proposed head-of-hollow fill, as well as the drainage, slope
stability, and prospective land use. Revegetation usually
proceeds as soon as erosion and siltation protection have
been completed. This technique is avoided in areas where
under-drainage materials contain high concentrations of
pollutants, since the resultant drainage would require
treatment to meet pollution-control requirements.
Erosion Control
Although regrading is the most essential part of surface-
mine reclamation, it cannot be considered a total
reclamation technique. There are many other facets of
surface-mine reclamation that are equally important in
achieving successful reclamation. The effectivenesses of
regrading and other control techniques are interdependent.
Failure of any phase could severly reduce the effectiveness
of an entire reclamation project.
The most important auxiliary reclamation procedures employed
at regraded surface mines or refuse areas are water
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diversion and erosion and runoff control. Water diversion
involves collection of water before it enters a mine area
and conveyance of that water around the mine site, as
discussed previously. This procedure decreases erosion and
pollution formation. Ditches are usually excavated upslope
from a mine site to collect and convey water. Flumes and
pipes are used to carry water down steep slopes or across
regraded areas. Riprap and dumped rock are sometimes used
to reduce water velocity in the conveyance system.
Diversion and conveyance systems are designed to accommodate
predicted water volumes and velocities. If the capacity of
a ditch is exceeded/ water erodes the sides and renders the
ditch ineffective.
Water diversion is also employed as an actual part of the
mining procedure. Drainways at the bases of high walls
intercept and divert discharging ground water prior to its
contact with pollution-forming materials. In some
instances, ground water above the mine site is pumped out
before it enters the mine area, where it would become
polluted and require treatment. soil erosion is
significantly reduced on regraded areas by controlling the
course of surface-water runoff, using interception channels
constructed on the regraded surface.
There are a large number of techniques in use for
controlling runoff, with highly variable costs and degrees
of effectiveness. Mulching is sometimes used as a temporary
measure which protects the runoff surface from raindrop
impacts and reduces the velocity of surface runoff.
Velocity reduction is a critical facet of runoff control.
This is accomplished through slope reduction by terracing or
grading; revegetation; or use of flow impediments such as
dikes, contour plowing, and dumped rock. Surface
stabilizers have been utilized on the surface to temporarily
reduce erodability of the material itself, but expense has
restricted use of such materials in the past.
Re vegetation
Establishment of good vegetative cover on a mine area is
probably the most effective method of controlling runoff and
erosion. A critical factor in mine revegetation is the
quality of the soil or spoil material on the surface of a
regraded mine. There are several methods by which the
nature of this material has been controlled. Topsoil
segregation during stripping is mandatory in many states.
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This permits topsoil to be replaced on a regraded surface
prior to revegetation. However, in many forested, steep-
sloped areas, there is little or no topsoil on the
undisturbed land surface. In such areas, overburden
material is segregated in a manner that will allow the most
toxic materials to be placed at the base of the regraded
mine, and the best spoil material is placed on the mine
surface.
Vegetative cover provides effective erosion control; contri-
butes significantly to chemical pollution control; results
in aesthetic improvement; and can return land to
agricultural, recreational, or silvicultural usefulness. A
dense ground cover stabilizes the surface (with its root
system), reduces velocity of surface runoff, helps build
humus on the surface, and can virtually eliminate erosion.
A soil profile begins to form, followed by a complete soil
ecosystem. This soil profile acts as an oxygen barrier,
reducing the amount of oxygen reaching underlying materials.
This, in turn, reduces oxidation, which is a major
contributing factor to pollutant formation.
The soil profile also tends to act as a sponge that retains
water near the surface, as opposed to the original loose
spoil (which allowed rapid infiltration). This water
evaporates from the mine surface, cooling it and enhancing
vegetative growth. Evaporated water also bypasses toxic
materials underlying the soil, decreasing pollution
production. The vegetation itself also utilizes large
quantities of water in its life processes and transpires it
back to the atmosphere, again reducing the amount of water-
reaching underlying materials.
Establishment of an adequate vegetative cover at a mine site
is dependent on a number of related factors. The regraded
surface of many spoils cannot support a good vegetative
cover without supplemental treatment. The surface texture
is often too irregular, requiring the use of raking to
remove as much rock as possible and to decrease the average
grain size of the remaining material. Materials toxic to
plant life, usually buried during regrading, generally do
not appear on or near the final graded surface. If the
surface is compacted, it is usually loosened by discing,
plowing, or roto-tilling prior to seeding in order to
enhance plant growth.
Soil supplements are often required to establish a good
vegetative cover on surface-mined lands and refuse piles,
which are generally deficient in nutrients. Mine spoils are
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often acidic, and lime must be added to adjust the pH to the
tolerance range of the species to be planted. It may be
necessary to apply additional neutralizing material to
revegetated areas for some time to offset continued
pollutant generation.
Several potentially effective soil supplements are currently
undergoing research and experimentation. Flyash is a waste
product of coal-fired boilers and resembles soil with
respect to certain physical and chemical properties. Flyash
is often alkaline, contains some plant nutrients, and
possesses moistureretaining and soil-conditioning
capabilities. Its main function is that of an alkalinity
source and a soil conditioner, although it must usually be
augmented with lime and fertilizers. However, flyash can
vary drastically in quality—particularly, with respect to
pH—and may contain leachable materials capable of producing
water pollution. Future research, demonstration, and
monitoring of flyash supplements will probably develop the
potential use of such materials.
Limestone screenings are also an effective long-term neutra-
lizing agent for acidic spoils. Such spoils generally
continue to produce acidity as oxidation continues. Use of
lime for direct planting upon these surfaces is effective,
but it provides only short-term alkalinity. The lime is
usually consumed after several years, and the spoil may
return to its acidic condition. Limestone screenings are of
larger particle size and should continue to produce
alkalinity on a decreasing scale for many years, after which
a vegetative cover should be well-established. Use of large
quantities of limestone should also add alkalinity to
receiving streams. These screenings are often cheaper than
lime, providing larger quantities of alkalinity for the same
cost. Such applications of limestone are currently being
demonstrated in several areas.
Use of digested sewage sludge as a soil supplement also has
good possibilities for replacing fertilizer and
simultaneously alleviating the problem of sludge disposal.
sewage sludge is currently being utilized for revegetation
in strip-mined areas of Ohio. Besides supplying various
nutrients, sewage sludge can reduce acidity or alkalinity
and effectively increase soil absorption and moisture-
retention capabilities. Digested sewage sludge can be
applied in liquid or dry form and must be incorporated into
the spoil surface. Liquid sludge applications require large
holding ponds or tank trucks, from which sludge is pumped
and sprayed over the ground, allowed to dry, and disced into
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the underlying material. Dry sludge application requires
dryspreading machinery and must be followed by discing.
Limestone, digested sewage sludge, and flyash are all
limited by their availabilities and chemical compositions.
Unlike commercial fertilizers, the chemical compositions of
these materials may vary greatly, depending on how and where
they are produced. Therefore, a nearby supply of these
supplements may be useless if it does not contain the
nutrients or pH adjusters that are deficient in the area of
intended application. Flyash, digested sewage sludge, and
limestone screenings are all waste products of other
processes and are, therefore, usually inexpensive. The
major expense related to utilization of any of these wastes
is the cost of transporting and applying the material to the
mine area. Application may be quite costly and must be
uniform to effect complete and even revegetation.
When such large amounts of certain chemical nutrients are
utilized, it may also be necessary to institute controls to
prevent chemical pollution of adjacent waterways. Nutrient
controls may consist of preselection of vegetation to absorb
certain chemicals, or of construction of berms and retention
basins in which runoff can be collected and sampled, after
which it can be discharged or pumped back to the spoil. The
specific soil supplements and application rates employed are
selected to provide the best possible conditions for the
vegetative species that are to be planted.
Careful consideration should be given to species selection
in surface-mine reclamation. Species are selected according
to some land-use plan, based upon the degree of pollution
control to be achieved and the site environment. A dense
ground cover of grasses and legumes is generally planted, in
addition to tree seedlings, to rapidly check erosion and
siltation. Trees are frequently planted in areas of poor
slope stability to help control landsliding. Intended
future use of the land is an important consideration with
respect to species selection. Reclaimed surface-mined lands
are occasionally returned to high-use categories, such as
agriculture, if the land has potential for growing crops.
However, when toxic spoils are encountered, agricultural
potential is 'greatly reduced, and only a few species will
grow.
Environmental conditions—particularly, climate—are
important in species selection. Usually, species are
planted that are native to an area—particularly, species
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that have been successfully established on nearby mine areas
with similar climate and spoil conditions.
Revegetation of arid and semi-arid areas involves special
consideration because of the extreme difficulty of
establishing vegetation. Lack of rainfall and effects of
surface disturbance create hostile growth conditions.
Because mining in arid regions has only recently been
initiated on a large scale, there is no standard
revegetation technology. Experimentation and demonstration
projects exploring two general revegetation techniques—
moisture retention and irrigation—are currently being
conducted to solve this problem.
Moisture retention utilizes entrapment, concentration, and
preservation of water within a soil structure to support
vegetation. This may be obtained utilizing snow fences,
mulches, pits, and other methods.
Irrigation can be achieved by pumping or by gravity, through
either pipes or ditches. This technique can be extremely
expensive, and acquisition of water rights may present a
major problem. Use of these arid-climate revegetation
techniques in conjunction with careful overburden
segregation and regrading should permit return of arid mined
areas to their natural states.
Exploration. Development, and Pilot-Scale Operations
Exploration activities commonly employ drilling, blasting,
excavation, tunneling, and other techniques to discover,
locate, or define the extent of an ore body. These
activities vary from small-scale (such as a single drill
hole) to large-scale (such as excavation of an open pit or
outcrop face). Such activities frequently contribute to the
pollutant loading in wastewater emanating from the site.
Since available facilities (such as power sources) and ready
accessibility of special equipment and supplies often are
limited, sophisticated treatment is often not possible. In
cases where exploration activity is being carried out, the
scale of such operations is such that primary water-quality
problems involve the presence of increased suspended-solid
loads and potentially severe pH changes. Ponds should be
provided for settling and retention of wastewater, drilling
fluids, or runoff from the site. Simple, accurate field
tests for pH can be made, with subsequent pH adjustment by
addition of lime (or other neutralizing agents) .
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Protection of receiving waters will thus be accomplished,
with the possible additional benefits of removal of metals
from solution—either in connection with solids removal or
by precipitation from solution.
Development operations frequently are large-scale, compared
to exploration activities, because they are intended to
extend already known or currently exploited resources.
Because these operations are associated with facilities and
equipment already in existence, it is necessary to plan
development activities to minimize pollution potential, and
to use existing mine or mill treatment and control methods
and facilities. These operations should, therefore, be
subject to limitations equivalent to existing operations
with respect to effluent treatment and control.
Pilot-scale operations often involve small to relatively
large mining and beneficiation facilities even though they
may not be currently operating at full4 capacity or are in
the process of development to full-scale. Planning of such
operations should be undertaken with treatment and control
of wastewater in mind to ensure that effluent limitation
guidelines and standards of performance for the category or
subcategory will be met. Although total loadings from such
operations and facilites are not at the levels expected from
normal operating conditions, the compositions of wastes and
the concentrations of wastewater parameters are likely to be
similar. Therefore, implementation of recommended treatment
and control technologies must be accomplished.
Mine and Mill Closure
Mine closure (Underground). Unless well-planned and well-
designed abatement techniques are implemented, an
underground mine can be a permanent source of water
pollution.
Responsibility for the prevention of any adverse
environmental impacts from the temporary or permanent
closure of a deep mine should rest solely and permanently
with the mine operator. This constitutes a substantial
burden; therefore, it behooves the operator to make use of
the best technology available for dealing with pollution
problems associated with mine closure. The two techniques
»«cs^ frequently utilized in deep-mine pollution abatement
are treatment and mine sealing. Treatment technology is
well defined and is generally capable of producing
acceptable mine effluent quality. if the mine operator
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chooses this course, he is faced with the prospect of costly
permanent treatment of each mine discharge.
Mine sealing is an attractive alternative to the prospects
of perpetual treatment. Mine sealing requires the mine
operator to consider barrier and ceiling-support design from
the perspectives of strength, mine safety, their ability to
withstand high water pressure, and their utility for
retarding groundwater infiltration. In the case of new
mines, these considerations should be included in the mine
design to cover the eventual mine closure. In the case of
existing mines, these considerations should be evaluated for
existing mine barriers and ceiling supports, and the fi*..ir%
mine plan should be adjusted to include these considerations
if mine sealing is to be employed at mine closure.
Sealing eliminates the mine discharge and inundates the mine
workings, thereby reducing or terminating the production of
pollutants. However, the possibility of the failure of mine
seals or outcrop barriers increases with time as the sealed
mine workings gradually became inundated by ground water and
the hydraulic head increases. Depending upon the rate of
ground-water influx and the size of the mined area, complete
inundation of a sealed mine may require several decades.
Consequently, the maximum anticipated hydraulic head on the
mine seals may not be realized for that length of time. In
addition, seepage through, or failure of,.the barrier or
mine seal could occur at any time. Therefore, the mine
operator should be required to permanently maintain the
seals, or to provide treatment in the event of seepage or
failure.
Mine Closure (Surface). The objectives of proper
reclamation management of closed surface mines and
associated workings are to (1) restore the affected lands to
a condition at least fully capable of supporting the uses
which they were capable of supporting prior to any mining,
and (2) achieve a stability which does not pose any threat
to public health, safety, or water pollution. With proper
planning and management during mining activities, it is
often possible to minimize the amount of land disturbed or
excavated at any one time. In preparation-for the day the
operation may cease, a reclamation schedule for restoration
of existing affected areas, as well as those which will be
affected, should be specified. The use of a planned
methodology such as this will return the workings to their
premined condition at a faster rate, as well as possibly
reduce the ultimate costs to the operator.
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To accomplish the objectives of the desired reclamation
goals, it is mandatory that the surface-mine operator
regrade and revegetate the disturbed area during, or upon
completion of, mining. The final regraded surface
configuration is dependent upon the ultimate land use of the
specific site, and control practices described in this
report can be incorporated into the regrading plan to
minimize erosion and sedimentation. The operator should
establish a diverse and permanent vegetative cover and a
plant succession at least equal in extent of cover to the
natural vegetation of the area. To assure compliance with
these requirements and permanence of vegetative cover, the
operator should be held responsible for successful revege-
tation and effluent water quality for a period of five full
years after the last year of augmented seeding. In areas of
the country where the annual average precipitation is 6H cm
(26 in.) or less, the operators assumption of
responsibility and liability should extend for a period of
ten full years after the last year of augmented seeding,
fertilization, irrigation, or effluent treatment (Reference
30).
Mill closure. As with closed mines, a beneficiation faci-
lity's potential contributions to water pollution do not
cease upon shutdown of the facility. Tailing ponds, waste
or refuse piles, haulage areas, workings, dumps, storage
areas, and processing and shipping areas often present
serious problems with respect to contributions to water
pollution. Among the most important are tailing ponds,
waste piles, and dump areas. Since no wastewater is
contributed from the processing of ores (the facility being
closed), the ponds will gradually become dewatered by
evaporation or by percolation into the subsurface. The
structural integrity of the tailing-pond walls should be
periodically examined and, if necessary, repairs made.
Seeding and vegetation can assist in stabilizing the walls,
prevent erosion and sedimentation, lessen the probability of
structural failure, and improve the aesthetics of the area.
Refuse, waste, and tailing piles should be recontoured and
revegetated to return the topography as near as possible to
the condition it was in before the activity. Techniques
employed in surface-mine regrading and revegetation should
be utilized. where mills are located adjacent to mine
workings, the mines can be refilled with tailings. Care
should be taken to minimize disruption of local drainage and
to ensure that erosion and sedimentation will not result.
Studies have indicated that to insure success of
revegatation efforts, maintenance of such refuse or waste
425
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piles and tailing-disposal areas should be performed for at
least five years after the last year of regrading and
augmented seeding. In areas of the country where the annual
average precipitation is 64 cm (26 in.) or less,
maintenance should extend for a period of ten full years
after the last year of augmented seeding, fertilization,
irrigation, or effluent treatment (Reference 30).
TREATMENT TECHNOLOGY
Each of the techniques currently employed in the ore mining
and dressing industry, as well as advanced waste treatment
technology which might be employed in present or future
operations, is discussed in this section.
The treatment technologies currently practiced in the ore
mining and dressing industry encompass a wide variety of
techniques ranging from the very simple to the highly
sophisticated. While a limited number of basic treatment
practices are standard (settling or tailing ponds, pH
control, etc.) and employed at almost all operations,
individual operations have approached specific pollution
problems in many different ways.
Impoundment Systems
This group of systems utilizes treatment technology which is
primarily designed to deal with suspended solids, but which
is frequently used with such other techniques as pH control,
to accomplish removal of dissolved constituents as well.
Tailing Ponds. This type of treatment is the most common
treatment technique used in the ore mining and dressing
industry today. The design of a tailing pond is primarily
for suspended solid removal and retention. Such a pond must
be large enough to provide sufficient retention time and
quiescent conditions conducive to settling. If properly
designed, and if retention time and surface area are
sufficient, a tailing pond may also effect to some degree
the stabilization of oxidizable constituents as well as the
balancing of influent quality and quantity fluctuations and
the storage of storm water.
Tailing ponds are often situated to capitalize upon natural
terrain factors in order to minimize the requirements for
dam construction. The containment dam is often constructed
of available earth and rock materials, as well as tailings.
In other cases, concrete basins may be constructed. Because
of natural terrain conditions, they may be constructed using
426
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one, two, three, or even four walls. The containment dam
must be raised periodically to accommodate the rising level
of contained tailings and water. In most cases, the basin
provides perpetual storage for any materials settled out of
the water treated. Retention time in ponds has been
reported to vary from as little as four hours to as much as
several months at average flow conditions (for discharging
systems).
water leaves a tailing pond by decantation, evaporation,
seepage through the dam or to underlying materials, or by
discharge. Decanted water may be recycled for use in the
mill, discharged, or treated further. In some operations,
in arid or semi-arid areas, evaporation from the tailing-
pond surface may equal the rate of input, allowing zero-
discharge operation of the pond without recycle of water.
Seepage losses from tailing ponds may flow into permeable
underlying strata and enter ground water, or may flow
through the containment dam and result in surface flows of
water. seepage waters are often collected in ditches and
pumped back into the tailing pond. Seepage may also be
limited by the use of pond liners of various materials
(clay, asphalt, plastic, etc.).
Low-cost, relatively simple construction and the ability to
perform multiple functions simultaneously have led to the
wide acceptance of tailing ponds as a prime treatment and
tailing-disposal method utilized by the ore mining and
dressing industry. There are- a number of problems
associated with the utilization of tailing ponds as
treatment facilities, however. Improper design of inlet and
discharge locations, insufficient size and number, and
insufficient retention time are the most common problems.
Algal growths in tailing ponds are quite common during warm
months, a factor which may influence such effluent water-
quality parameters as TOC, COD, TSS, and BOD. A minimum
retention time of 30 days and the added capability of
retaining runoff associated with a storm likely to occur
once in 20 years are recommended by one source (Reference
31) .
The relative advantages and disadvantages of a tailing pond
as a treatment system are listed below.
427
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Advantages'
Disadvantages
Performs large number of
treatment processes—parti-
cularly, suspended-solid
removal.
Can achieve high treatment
efficiency and often pro-
duce acceptable effluent
quality.
Often, only practical means
of long-term solids
disposal
Large retention has a balan-
cing effect on effluent
quality.
Large surface area aids
oxidation and evaporation.
Lacks responsive means of
control; difficult to optimize
large number of processes
performed.
Covers large surface area—may
contribute high net precipita-
tion to overall water balance;
land availability and topo-
graphy influence location.
Creates potentially severe
rehabilitation problem if tail-
ings contain sulfide minerals.
Often difficult to isolate from
contributing drainage areas—
storm water influences retention.
Subject to climatic variations—
particularly, thermal skimming
and seasonal variation in bio-
oxidation efficiency.
Often difficult to ensure good
flow distribution.
Requires careful control of
seepage through dams.
Installation expensive in some
situations, due to high cost of
retaining structures.
Can often be constructed
using mining equipment
and materials.
Little operating expertise
normally required.
Commonly used treatment
method, familiar to
industry.
Clear supernatant water may
serve as a reservoir for
reuse.
Tailing ponds in the ore mining and dressing industry range
from pits to large, engineered structures of 1000 acres or
more with massive retaining dams. For large tailing dams,
wall heights of 61 meters (200 feet) or more have been
reached by building up the dams over a period of time.
Routinely reached levels of suspended-solid concentrations
in treated effluent range from 10 to 30 mg/1 at mines and
mills visited or surveyed as part of this study. In tailing
ponds with decant structures for recycle of water, levels in
excess of 50 mg/1 of suspended solids were rarely observed.
428
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Settling Ponds. settling ponds differ from tailing ponds
primarily in size and in the concentrations of influent
solids treated. In general, relatively low initial solid
loads are removed, necessitating only occasional dredging to
maintain adequate settling volume behind the dam.
Suspended-solid removal to very low levels is often possible
when initial concentrations of suspended solids are low.
Settling ponds find their greatest usefulness in association
with mines having low wastewater solids loads.
Such ponds may serve a variety of purposes in addition to
removal of suspended solids, including COD reduction and
cooling. As basins for a variety of chemical treatments,
they can provide sufficient retention time for completion of
reactions, for pH control, for chemical precipitation, and
for the removal of solids produced.
Secondary Settling Ponds. settling ponds or tailing ponds
are frequently used in a multiple arrangement. The purpose
of this scheme is to further reduce suspended-solid loading
in the sequential ponds and to allow the subsequent use of
precipitation or pH control before discharge or recycle.
The ponds enable further reduction in suspended solids and
in dissolved parameters. An excellent example is the use of
secondary settling ponds (sometimes called polishing ponds)
in the coprecipitation of radium with barium.
Clarifiers and Thickeners
A method of removing large amounts of suspended solids from
wastewater is the use of clarifiers or thickeners, which are
essentially large tanks with directing and segregating
systems. The design of these devices provides for
concentration and removal of suspended and settleable solids
in one effluent stream and a clarified liquid in the other.
Clarified waters may be produced which have extremely low
solids content through proper design and application.
Clarifiers are not generally capable of handling tailing-
solid levels above about 50 percent, due to the necessity
for rake operation and hydraulic transport of suspended
solids from the device. The concentration from a mine-water
clarifier at one site, for example, was observed to be 3
mg/1 suspended solids.
Clarifiers may range in design from simple units to more
complex systems involving sludge blanket pulsing or sludge
recycle to improve settling and increase the density of the
sludge. Settled solids from clarifiers are removed
429
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periodically or continuously for either disposal or recovery
of contained values. Thickeners are used when the main
purpose is to produce a clarified overflow with a
concentrated tailing effluent in the underflow.
Thickeners have a number of distinct advantages over
settling or tailing ponds:
(1) Less land space is required. Area-for-area, these
devices are much more efficient in settling
capacity than ponds.
(2) Influences of rainfall are reduced compared to
ponds. If desired, the clarifiers and thickeners
can be covered.
(3) since the external construction of clarifiers and
thickeners consists of concrete or steel (in the
form of tanks), infiltration and rain-water runoff
influences do not exist.
(4) Thickeners can generally be placed adjacent to a
mill, making reclaim water available nearby with
minimal pumping requirements.
The use of clarifiers and thickeners, together with tailing
or settling ponds, may improve treatment efficiency; reduce
the area needed for tailing ponds; and facilitate the reuse
or recycle of water in the milling operation. The use of
flocculants to enhance the performance of thickeners and
clarifiers is common practice.
Clarifiers and thickeners also suffer some distinct
disadvantages compared to ponds:
(1) They have mechanical parts and, thus, require
maintenance.
(2) They have limited storage capacity for either
clarified water or settled solids.
(3) The internal sweeps and agitators in thickeners and
clarifiers require more power and energy for
operation than ponds.
Flocculation
This treatment process consists basically of adding reagents
to the treated waste stream to promote settling of suspended
430
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solids. The solids may be deposited in tailing ponds (where
high suspended solids are involved) or in settling ponds or
clarifier tanks (in cases of lower solids loads).
Flocculating agents increase the efficiency of settling
facilities and are of several general types: ferric
compounds, lime, aluminum sulfate, and cationic or anionic
polyelectrolytes. Causticized wheat and corn starch have
also been used. The ionic types, such as alum, ferrous
sulfate, lime, and ferric chloride, function by destroying
the repelling double-layer ionic charges around the
suspended particles and thereby allowing the particles to
attract each other and agglomerate. Polymeric types
function by forming physical bridges from one particle to
another and thereby agglomerating the particles. Recyclable
magnesium carbonate has also been proposed as a flocculant
in domestic water treatment.
Flocculating agents are added to the water to be treated
under controlled conditions of concentration, pH, mixing
time, and temperature. They act to upset the stability of
the colloidal suspension by charge neutralization and
flocculation of suspended solids, thus increasing the
effective diameter of these solids and increasing their
subsequent settling rate.
Flocculating agents are most commonly used after the larger,
more readily settled particles (and loads) have been removed
by a settling pond, hydrocyclone, or other treatment.
Agglomeration, or flocculation, can then be achieved with
less reagent, and with less settling load on the polishing
pond or clarifier.
Flocculation agents can be used with minor modifications and
additions to existing treatment systems, but the costs for
the flocculating chemicals are often significant. Ionic
types are used in concentrations of 10 to 100 mg/1 in the
wastewater, while the highest-priced polymeric types are
effective in concentrations of 2 to 20 mg/1.
The effectiveness and performance of individual flocculating
systems may vary over a substantial range with respect to
suspended-solid removal, accessory removal of soluble com-
ponents by adsorptive phenomena, and operating
characteristics and costs. Specific system performance sust
be analyzed and optimized with respect to mixing time,
flocculant addition level, settling- (detention) time,
thermal and wind-induced mixing, and other factors.
431
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Centrifuqation
Cen-trif ugation, which may be considered as a form of forced
or assisted settling, may be feasible in specific control
applications. With the volume of gross wastewater flows at
most mine/mill complexes, it is probable that centrifugation
may be more applicable to component in-process waste
streams. The presence of abrasive components or significant
amounts of solid material smaller than approximately 5
micrometers in diameter in the treated water would tend to
disqualify centrifugation as a solid-removal option.
Hydrocyclones
While hydrocyclones are widely used in the separation,
classification, and recovery operations involved in mineral
processing, they are used only infrequently for wastewater
treatment. Even the smallest-diameter units available
(stream-velocity and centrifugal-separation forces both
increase as the diameter decreases) are ineffective when
particle size is less than 25 to 50 micrometers. Larger
particle sizes are relatively easy to settle by means of
small ponds, thickeners or clarifiers, or other gravity-
principle settling devices. It is the smaller suspended
particles that are the most difficult to remove, and it is
these that cannot be removed by hydrocyclones but may be
handled by ponds or other settling technology. Also, hydro-
cyclones are of doubtful effectiveness when flocculating
agents are used to increase settling rates. This method is
generally most effective in the 25- to 200-micrometer size
range for particles.
Filtration
Filtration is accomplished by passing the wastewater stream
through solid-retaining screens or cloths or particulate
materials such as sand, gravel, coal, or diatomaceous earth
using gravity, pressure, or vacuum as the driving force.
Filtration is a versatile method in that it can be used to
remove a wide range of suspended particle sizes.
A variety of filtration techniques, including disc and drum
units, find process applications and may be applicable to
some waste streams—particularly, where segregated waste
streams require special treatment.
Likely applications of filtration include pretreatment of
input streams using reverse-osmosis and ion-exchange units
(discussed later).
432
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High values contained In suspended solids may, in some
cases, offset the capital and operating expenses of
filtering systems. The use of filtration as a normal unit
process in treating uranium-mill tailings for value recovery
through countercurrent washing is indicative of the possible
use of filtration in tailing treatment. In this instance,
the final washed tail filter cake is reslurried for
transport to the tailing pond. In situations where
biological treatment of component or combined waste streams
is required to reduce BOD, COD, or bacterial loads,
trickling filters may be required, but their application as
primary treatment for the bulk mine or mill effluent is
considered unlikely.
The specific applicability and size specifications for
filter modules must be evaluated on a case-by-case basis,
taking into account the process stream characteristics,
solids filterability, desired dryness of filter cake, and
other parameters.
Ultimate clarification of filtered water will be a function
of particle size, filter-media porosity, filtration rate,
and other variables. In general, for the majority of mine
or mill wastewaters subjected to this treatment, post-
treatment suspended-solid levels of less than 20 percent of
influent loadings are anticipated. Thus, if used after
primary flocculation and settling, suspended solids levels
of 20 mg/1 should be obtainable.
Neutralization
Adjustment of pH is the simplest and most common chemical
treatment practiced in the mining and milling industry
today. The addition of either acidic or basic constituents
to a wastewater stream to achieve neutralization generally
influences the behavior of both suspended and dissolved
components. In most instances of interest in mining and
milling activities, wastewater is treated by base addition
to achieve pH conditions in the range of 6 to 9.
Acid waste streams (considerably more common than highly
basic effluents) may be neutralized by addition of a variety
of basic reagents, including lime (calcium oxide),
limestone, dolomite (CaMg(C03J 2) , magnesite (MgC03), sodium
hydroxide, soda ash (sodium carbonate), ammonium hydroxide,
and others to raise the pH of treated waste streams to the
desired level. Lime is most often used because it is
inexpensive and easy to apply. Soda ash and caustic soda
are commonly used to supply alkalinity in leaching and
433
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hydrometallurgical processes, where the formation of calcium
precipitates would be objectionable, but the cost advantages
of using lime generally preclude the use of soda ash and
caustic soda in large-scale waste treatment.
Ammonia neutralization is most frequently a processing
technique, where ammonia affords a strong advantage in being
volatile in the final product, allowing the recovery of
nearly pure oxides. In waste treatment, its volatility is a
disadvantage. Because of the COD it presents, its toxicity,
and the production of undesirable nitrites and nitrates as
oxidation products, its use is not widespread, although
ammonia neutralization of a wastewater stream is practiced
at one site in the ferroalloy ore mining and milling
category.
Excessively basic waste streams are not common but may be
neutralized by addition of an acid—most commonly, sulfuric.
Since many heavy metals form insoluble hydroxides in highly
basic solutions, sedimentation prior to neutralization may
prevent the resolubilization of these materials and may
simplify subsequent waste-treatment requirements. Carbon
dioxide has also been used to adjust the pH of effluent
waters to acceptable levels prior to discharge (recarbona-
tion).
Essentially any wastewater stream may be treated to a final
pH within the range of 6 to 9. Generally, the stream will
be sufficiently uniform to allow adequate pH control based
only on the volume of flow and predetermined dosage rates,
with periodic adjustments based on effluent pH. Automated
systems which monitor and continously adjust the
concentration of reacfents added to the wastewater are also
currently available.
As discussed previously, pH control is often used to control
solubility (also discussed under Chemical Precipitation Pro-
cesses) . Examples of pH control being used for
precipitating undesired pollutants are:
(1) Fe{+3) * 3OH(-) > Fe(OH)3_
(2) Mn(+2) * 20H(-) > Mn(OH).2
(3) Zn(*2) * OH(-) > Zn(OH)2
(4) Pb(*2) + 20H > Pb(OH)2
(5) Cu «• 20H(-) > Cu(OB)2.
434
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Reaction (1) is used for removal of iron contaminants.
Reaction (2) is used for removal of manganese from
manganese-containing wastewater. Reactions (3) , (4) , and
(5) are used on wastewater containing copper, lead, and zinc
salts. The use of lime to attain a pH of 7 will
theoretically reduce heavy metals to these levels (Reference
32):
Metal Concentration (mg/1 at pH 7)
Cu(*2) 0.2 to 0.3
Zn(+2) 1.0 to 2.5
Cd( + 2) 1.0
Ni(+2) 1.0
Cr(*2) 0.4
The careful control of pH, therefore, has other ancillary
benefits, as illustrated above. The use of pH and
solubility relationships to improve removal of wastewater
contaminants is further developed below.
Chemical Precipitation Processes
The removal of materials from solution by the addition of
chemicals which form insoluble (cr sparingly soluble)
compounds with them is a common practice in
hydrometallurgical ore beneficiation and in waste treatment
in the ore mining and dressing industry. It is especially
useful for the removal of heavy metals from mine effluents
and process wastes.
To be successful, direct precipitation depends primarily
upon two factors:
(1) Achievement of a sufficient excess of the added ion
to drive the precipitation reaction to completion.
(2) Removal of the resulting solids from the waste
stream.
If the first requirement is not met, only a portion of the
pollutant(s) will be removed from solution, and desired
effluent levels may not be achieved. Failure to remove the
precipitates formed prior to discharge is likely to lead to
redissolution, since ionic equilibria in the receiving
435
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stream will not, in general, be those created in treatment.
Effective sedimentation or filtration is, thus, a vital
component of a precipitation treatment system and frequently
limits the overall removal efficiency. Sedimentation may be
effected in the tailing basin itself, in secondary or
auxiliary settling ponds, or in clarifiers. Industry
experience has shown the value of treatment of wastes prior
to delivery to the tailing impoundment. Benefits derived
include: improved settling of precipitates due to
interaction with tailings; simplified disposal of sludges;
and, generally, suppressed solubility of materials in
tailing solids.
The use of precipitation for wastewater treatment varies
from lime treatments (to precipitate sulfates, fluorides,
hydroxides, and carbonates) to sodium sulfide precipitation
of copper, lead, and other toxic heavy metals. The
following equations are examples of precipitation reactions
used for wastewater treatment:
(1) Fe(+3) + Ca(OH)2 > Ca (+2) + Fe(OH)3_
(2) Mn(*2) * Ca(OH)2 > Ca( + 2) * Mn(OH)2
(3) Zn(+2) «• Na2C03 > Na(+) + ZnC03_
(H) SOt£(-2) * Ca(OH)2 > CaSOjt * 20H(-)
(5) 2F(-) + Ca(OH)2 > Ca¥2 + 20H(-)
One drawback of the precipitation reactions is that of
varying solubility and unknown interactions of several metal
compounds, and the possibility of widely divergent formation
and precipitation rates, limit the ability of this treatment
to deal with all waste constituents.
Lime Precipitation. The use of lime to cause chemical
precipitation has gained widespread use in the ore mining
and dressing industry because of its ease of handling,
because of its economy, and because of its effectiveness in
treatment of a great variety of dissolved materials. The
use of other bases is, of course, possible, as previously
discussed. However, the use of lime as a treatment reagent
is probably the best-known and best-studied method.
A typical lime neutralization/precipitation system is
illustrated in Figure VII-1. Generally, water is pumped or
discharged to a holding or settling pond, where suspended-
solid levels are reduced. Either in conjunction with the
436
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Figure VIM. LIME NEUTRALIZATION AND PRECIPITATION PROCESS FOR
TREATMENT OF MINE WATER PRIOR TO DISCHARGE
FROM MINE OR MILL
'*•'• .••,•*•'.••.'••;.•«. • -.J.:> T ..*•
SLUDGE
REQUIRING
DISPOSAL
TO
DISCHARGE
SOURCE: Reference 33
437
-------
primary pond itself or in a mixing basin or tank, a slurry
of lime and water is delivered for mixing with the
wastewater stream. Secondary settling ponds are then used
to collect the usually high volumes of sludges which may be
recovered. These impoundments may be dredged periodically
to remove sludges, or the sides of the basin may be built
up. Discharge of the water then usually takes place.
The treatment conditions, dosages, and final pH must be
optimized for any given waste stream, but, in general,
attainment of a pH of at least 9 is necessary to ensure
removal of heavy metals. To attain desired levels of
control for many heavy metals, it is necessary to attain a
pH of 10 to 12 in many instances (refer to Figure VII-3).
The levels of concentration attainable in an actual
operating system may vary from the limits predicted on the
basis of purely theoretical considerations, but extremely
low levels of metals discharged have been reached by the use
of this treatment method. Figure VI1-2 illustrates the
theoretical solubilities of several metal ions as a function
of pH. The minimum pH value for complete precipitation of
metal ions as hydroxides is shown in Figure VII-3. An
example of the performance of lime precipitation at elevated
pH is given for Fe, Pb, Zn, Cd, Hg, and F in Figure VII-U.
These data are taken from a combination zinc plant/lead
smelter, where removal efficiency is plotted against pH.
The curves are not always complete for lack of data; it is
not advisable to extrapolate them without further
measurements, because chemical changes may occur that
reverse an apparent consistent trend.
Purely theoretical considerations of metal-hydroxide
solubility relationships suggest that the metal levels
tabulated below are attainable (Reference 31) .
Final Concentration
Metal (microgram per liter! pH
Cu( + 2) 1 to 8 9.5
Zn( + 2) 10 to 60 10
Pb 1 8
Fe(total) 1 8 (if totally Ferric)
Many factors, such as the effects of widely differing solu-
bility products, mixed-metal hydroxide complexing, and meral
438
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Figure VII-2. THE RELATIONSHIP OF THEORETICAL SOLUBILITIES OF METAL IONS
ASA FUNCTION OF pH
100
> 0.1
0.01
0.001
0.0001
678
SOURCE: Adapted from Reference 34
439
-------
Figure Vll-3. MINIMUM pH VALUE FOR COMPLETE PRECIPITATION OF METAL IONS AS
HYDROXIDES
11.0
10.0
9.0
8.0
7 Q
6.0
5.0
4.0
3.0
2.0
1.0
on
7.2
(
i
4.:
i t
^m
I
5.2
5.2
1
8.4
M
\
3.3
9.E
••
9.1
•••
1
1 _i _t
o.t
^
)
Ni+2 Fe+2 Cd+2
LIME
NEUTRALIZATION
LtME PRECIPITATION
SOURCE: Reference 33
440
-------
Figure VII-4. HEAVY-METAL PRECIPITATION vs pH FOR TAILING-POND
EFFLUENT pH ADJUSTMENTS BY LIME ADDITION
50
60
o
UJ
5 70
o
2
80
a.
u.
O
90
100 -
3579
PH
11
13
SOURCE: Reference 35
441
-------
chelation, render these levels of only limited value when
assessing attainable concentrations in a treatment system.
Among the metals effectively removed at basic pH are: As,
Cd, Cu, Cr(+3), Fe, Mn, Ni, Pb, and Zn. Based upon
published sources, industry data, and analysis of samples,
it appears that the concentrations given in the tabulation
below may be routinely and reliably attained by hydroxide
precipitation in the ferroalloy- ore mining and milling
industry. (Reference 31) .
Metal Concentration Metal Concentration
As 0.05 Mn 1.0
Cd 0.05 Ni 0.05
Cu 0.03 Pb 0.10
Cr( + 3) 0.05 Zn 0.15
Fe 1.0
Some metallic pollutants of interest in the uranium-ore
mining and milling industry, together with results produced
by lime precipitation in conjunction with a rise in pH from
6.7 to 12.7, are shown below:
Metal Concentration (mq/1)
pH=6.7 pH=12.7
Cd 1.3 less than 0.02
Fe 6.0 less than 0.1
Ni 0.13 less than 0.05
Cu 5.3 0.05
Zn 31.25 0.11
Mn 26.5 0.04
Data from previous work demonstrate the use of lime
precipitation with settling in tailing pond for the base and
precious metal industry. These data are summarized below.
(Reference 36) .
Metal Concentration
(mg/1)
Cu 0.03
Zn 0.15
Pb 0.1
442
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Fe (total) 1.0
Other examples of the efficiency of lime precipitation as a
treatment method are discussed by ore category later in this
section. An important point is illustrated in the data pre-
viously presented here, however. All metals do not remain
insoluble at elevated pH. Examples of that phenomenon are
the variations in solubilities of lead and zincr which are
precipitated at approximately pH 9. Above pH 9, these
metals rapidly resolubilize. (See Reference 37.)
Sulfide Precipitation. The use of sulfide ion as a
precipitant for removal of heavy metals accomplishes more
complete removal than the use of hydroxide for
precipitation. Sulfide precipitation is currently being
used in wastewater treatment to reduce mercury levels to
extremely low levels (Reference 38). Highly effective
removal of Cd, Cu, Co, Fer Hg, Mn, Nir Pbr Zn, and other
metals from mine and mill wastes can be accomplished by
treatment with either sodium sulfide or hydrogen sulfide.
The use of this method depends somewhat on the availability
of methods for effectively removing precipitated solids from
the waste stream, and on removal of the solids to an
environment where reoxidation is unlikely.
Several steps enter into the process of sulfide
precipitation:
(1) Preparation of sodium sulfide. Although this
product is often in oversupply from byproduct
sources, it can also be made by the reduction of
sodium sulfate, a waste product of acid-leach
milling. The process involves an energy loss in
the partial oxidation of carbon (such as that
contained in coal).
Na.2S0.4 + 4C > Na2S * 4CO (gas)
(2) Precipitation of the pollutant metal (M) in the
waste stream by an excess of sodium sulfide:
Na^s * MS04 > MS (precipitate) + Na.2304,
(3) Physical separation of the metal sulfide in
thickeners or clarifiers, with reducing conditions
maintained by excess sulfide ion.
(4) Oxidation of excess sulfide by aeration:
443
-------
Na2S + 20^ >
This process usually involves iron as an
intermediary and is seen to regenerate unused
sodium sulfate.
On the whole, sulfide precipitation removes both heavy
metals and some sulfur from waste streams but requires some
energy expenditure.
In practice, sulfide precipitation can be applied only when
the pH is sufficiently high (greater than about 8) to assure
generation of sulfide ion rather than bisulfide or hydroc^r.
sulfide gas. It is then possible to add just enougn
sulfide, in the form of sodium sulfide, to precipitate the
heavy metals present as cations; alternatively, the process
can be continued until dissolved oxygen in the effluent is
reduced to sulfate and anaerobic conditions are obtained.
Under these conditions, some reduction and precipitation of
molybdates, uranates, chromates, and vanadates may occur,
but ion exchange seems more appropriate for the removal of
these anions.
Because of the toxicity of sulfide ion, and of hydrogen
sulfide gas, the use of sulfide precipitation may require
both pre-and post-treatment and close control of reagent
additions. Pretreatment involves raising the pH of the
waste stream to minimize evolution of H^S, which would pose
a safety hazard to personnel. If desirable, this may be
accomplished at essentially the same point as the sulfide
treatment, or by addition of a solution containing both
sodium sulfide and a strong base (such as caustic soda).
The sulfides of many heavy metals, such as copper and
mercury, are sufficiently insoluble to allow essentially
complete removal with extremely low residual sulfide levels.
Treatment for these metals with close control on sulfide
concentrations could be accomplished without the need for
additional treatment. Where higher residual sulfide ion
concentrations pertain, adequate aeration should be provided
to yield an effluent saturated with oxygen.
Coprecipitation. In coprecipitation, materials which
cannot be removed from solution effectively by direct
precipitation are removed by incorporating them into
particles of another precipitate, which is separated by
settling, filtration, or another technique such as
flotation. Current practice is exemplified by the use of
barium chloride addition for radium control in the uranium
industry.
444
-------
Radium sulfate (RaS
-------
TABLE VIM. USE OF BARIUM SALTS FOR REMOVAL OF
RADIUM FROM WASTEWATER
(•I REMOVAL Of RADIUM BV COPRECIPIT ATION
EFFLUENT pH
Nautral
Acidic
REAGENT
BaSO4
BaCO3
B.CI-*
BaCOj
BaCtj
AMOUNT
Img// 1
OF
REAGENT
ADDED
300
1000
100
200
30
80
100
200
100
200
300
100
RADIUM CONCENTRATIONS
(picocurm/ 1 )
BEFORE
TREATMENT
100
300
470
490
800
440
400
430
ISO
160
ISO
ISO
AFTER
TREATMENT
30
70
3D
4O
20
6
2
2
18
20
30
Slo IS
PERCENTAGE
OF
RADIUM
REMOVED
70
77
V4
92
97
99
99
99
8B
87
60
90 10 97
Ibl REMOVAL OF RADIUM USING BARIUM CHLORIDE COPRECIPITATlON ALONE
OPERATION
9403 '
9405 '
«40SM1
Mill$ ^ititi
94151"
94161
9402
9402-
9411
Minat 941 1*12
94121-9
9408
9408'
AMOUNT
lmg/» |
OF BaClj
ADDED
7.42
9.S
9S'
10
0.1
34
20
20'
5
10
10.4
ss
55
RADIUM CONCENTRATIONS Ipicocur.n/ / 1
BEFORE BaClj TREATMENT
Tom
111 (*MI
1S.9 l»l. SI
39.2 1*3.91
451 1 1*0.31
21.3 1+0.21
127.4 (-0.61
40 1*0.31*
1S9 1*16)
35.4 1*0.31*
589 1-5.71
489 1*0.2)
123.8 («15|'°
142 1*141
Di«aol»ad
_
33.3 1*3.31
4374 1*2.1)
49 1*0.21
117.5 I*.2.S)
16.6 I*0.2I6
1S7 1*171
165 I»2.0I8
60.2 1*6.01
4.7 1*0.11
37.7 (»OJI8
120 1*121
AFTER BaCI, TREATMENT
Total
4.09 1*0.41)
< 1.0
S.OS 1*0.51
231.7 1*0.11
1S.S 1*0.11
18.2 1*0.41
16.9 1*0.3)'
7.9 1*0.81
8.4 1*0. tl8
< 2
10.9 1*0.21
2.1 1*0.231 10
1.12 1*0.111
Omolvad
^
<2
2.7 1*0.11
0.3 1*0.11
12.5 1*0.61
1.6 I»O.JI7
4.18 1*0.42)
0.2 1*0. II8
n.i.
1.6 1*0.11
0.6 1*0.11*
<09
PERCENTAGE
OF RADIUM
REMOVED
Tout
96.3
>93.7
87.1
48.6
27.2
BS.1
57. 7
95
76.1
>98
77.7
98.3
M
OnioUad
_
>939
99.4
93.9
89.4
90.4
97
98.7
n.i.
66.0
9B.4
>99
1. Dai* obtained from nngl« grab umplmg and analynt (April. 1976).
2. Ca*rul«r«l valu* b««d on iv«rafa flow and annual BaCI^ uuoa
3. CoinMnv oal* for January through Dvcamovr 197b (A«ara9« of 12 monthly maantt.
4. EHIutnt tamplwj prior lo final wtlling I April. 19761
S. BaCtj addad « a durry with lima 14 mo// CaO I
6. Data obtainad from analyst! of nwo graD umplat 1 April, 1976).
7. Data abuinad Irom analyut of rwo 124iour compoma umpitt iApril 1976)
8. Company data far Fabruary 1975 (Avaraaa ol 12 grab wmpiati
9. Final aiicharga to dry nvaiarcouraa.
10. Colorado Dapi. of Haalth data for pariod January 1973 tnrough Faaruary 197S
lAnaraot of 24 umplai analyiad for "axtractabla" flj 226).
11. Data oblainad from a camp«ita of two grab umplai lapratanting two Mparaia inlluani pomli IMay.19771
12. Nota that tha doiaga hal doublad apparantly anhancing tha traalmant ivllam ilficiancy.
• Updatad data obtamad during wmplmg trip* owuring April-May. 1977. All umoin. unla«
atharwifa indicitad. ara 24-fi> compoiitai
t Dotaga nt« »a aaiumad to ramain tha lama M pravioui raiat.
n.a not analviad
I I ParanthatK*! valuat indicala analytical accuracy.
446
-------
they do not appear to represent a marketable product at this
time.
Vanadium is also subject to coprecipitation, with ferric
hydroxide, as ferric metavanadate. The best conditions
observed in laboratory studies conducted as part of this
effort involve the addition, to acid or neutral solutions,
of 2.5 times the stochiometric quantity of ferrous sulfate
needed to form ferric metavanadate, followed by aeration and
lime neutralization to a pH between 6 and 9. Reductions
from up to 200 mg/1 vanadium to less than 5 mg/1 have been
observed (Reference 42), which is in good agreement with
limited field observations of soil neutralization of
vanadium- and iron-bearing waste leaks. The coprecipitation
process may be more economical than ion-exchange methods of
removing vanadium in some instances — particularly, with
high concentrations of other solutes and low vanadium
concentration. The reaction can be expressed as:
6 NH4VO3 * 4 FeSOj* * HE2O + O2 >
2 Fe(VO3_).3 + 2 Fe(OH),3 + H2SO4 + 3 (NH4J 2 SO£
Treatment of the metavanadate with ferrous ion and
subsequent aeration drives the above reaction to the right.
It is not until the pH is elevated, however, that
coprecipitation of the ferric metavanadate and ferric
hydroxide is observed.
Other Precipitation systems. Other types of precipitation
systems have been employed, 'such as those used for the
precipitation of sulfate (Reference 43), fluoride (as
calcium fluoride), or others (Reference 44). Starch-
xanthate complexes have recently been reported to be
effective in aiding precipitation of a variety of metals,
including Cd, Cr, Cu, Pb, Hg, Ni, Ag, and Zn (Reference 45).
Scavenging or coprecipitation studies have been conducted on
municpal wastewater (Reference 46). in specialized cases,
precipitation may be induced by oxidation, which produces a
less soluble heavy-metal product. The chlorine oxidation of
Co(+2) to Co (+3) at a pH of approximately 5 produces the
insoluble Co.20.3 (xH20). Oxidation of Fe(+2) to Fe(+3)
results in the precipitation of hydrous ferric oxide, even
a4: relatively low pH. Oxidation of As(+3) to As (+4)
improves precipitation removal (Reference 45) . The use of
oxidation is further discussed later in this section.
447
-------
Reduction
Reduction techniques have particular applicability to the
removal of hexavalent chromium and copper from waste streams
in the ferroalloy-ore mining and milling industry. Copper
is often recovered in current practice by reduction of the
metal and subsequent deposition on scrap iron in the waste
stream (cementation). Since the effluent levels resulting
from cementation are still high, generally 10 mg/1 or more,
it is necessary to follow use of this process with another
removal step, such as hydroxide precipitation.
Reduction of chromates to trivalent chromium, with
subsequent precipitation of the chromium as the hydroxide,
is a standard waste-treatment practice in a number of
industries and may find application in the ore mining and
dressing industry, where leaching practices give rise to
wastewater contaminated with chromates. Commonly used
reducing agents include sulfur dioxide and ferrous salts of
iron. with sulfur dioxide and a pH of 2.5, chromate may be
reduced rapidly and completely. Removal of the Cr(OH)3_
precipitate formed in treatment of the relatively dilute
wastes to be expected in mill effluents nray prove difficult,
necessitating careful management of the treatment system and
the use of flocculants such as Fe(OH)3_ to aid in settling.
Effluent levels of 0.5 mg/1 of total chromium and 0.05 mg/1
of hexavalent chromium may be reliably attained by the
treatment (Reference 47).
Sodium borohydride reduction has been applied to reducing
soluble mercury levels in chlor-alkali and mercury
processing plants and to reducing lead levels in wastes
arising in the tetra-alkyllead manufacturing process (U.S.
Patents 3,736,253, 3,764,528, and 3,770,423). Stannous
(tin) compounds have been used for the reductive deposition
of palladium during electroplating processes.
Electroreduction of metals is widely practiced in
electrowinning and electrorefining systems for copper,
nickel, cobalt, and other metals.
Treatment in the ore mining and dressing industry differs
from the above techniques, chiefly because of the lower
concentrations of soluble, reducible species and because of
the presence of numerous other reducible species in the
wastewater. Unless preconditioning of treated waters is
employed, excessive reducing agent consumption may occur.
Secondary recovery systems (settling, filters, etc.) may be
necessary to permit removal of reduced components. The
recovery of values from waste residues is a potential option
with this treatment method, in some instances, application
of this process option to internal streams prior to
448
-------
discharge and/or combination with other waste streams may
offer substantial enhancement of value recovery from
treatment products.
Oxidation,. Aeration, and Air Stripping
A number of the waste components resulting from mining and
milling may be removed or rendered less harmful by oxidation
or removal to the atmosphere. Among these are cyanide,
sulfide, ammonia, and a variety of materials presenting high
COL levels. The simplest approach to effecting these
processes is aeration of the waste stream, which occurs
naturally in pumping it and in distributing it at the
tailing pond. More elaborate implementation achieves more
complete and rapid results in air strippers, and by
controlled introduction of stronger cxidants, such as
chlorine or ozone.
Cyanide (CN-) is removed by oxidation to cyanate (CNO-) and,
ultimately, to C02 and N2- This is accomplished in standard
practice by rapid chlorination at alkaline pH (about 10.5)
using caustic soda. The probable reaction with excess
chlorine has been expressed as:
2NaCN + 5C12 + 12NaOH > N_2 + 2Na2C03. * lONaCl * 6H20
A pH of 10 to 11 is recommended for operating conditions.
This process may be performed on either a batch or
continuous process. Approximately 2.72 kg (6 Ib) each of
caustic soda and chlorine are normally required to oxidize
0.45 kg (1 Ib) of cyanide. If metal-cyanide complexes are
present, extended chlorination for several hours may be
necessary.
In treatment of mill effluent in the gold milling industry,
some cyanide is lost in the process and is present in the
mill tailings. Some of the cyanide decomposes in the
tailing pond, and it appears that a high level of removal is
generally effected by naturally occurring oxidation in
tailing ponds. Except where cyanide is used as a leaching
reagent, high concentrations of cyanide are not normally
encountered. The use of cyanide as a depressant in the
flotation process is an additional source of cyanide in
waatewater. Effluent levels characteristically encountered
are less than 0.05 mg/1 total cyanide.
Where removal of low levels of cyanide is required, aeration
devices, auxiliary ponds or longer retention times may
frequently be adequate to achieve acceptable effluent
449
-------
quality. Complete destruction of cyanide in mill treatment
systems may be achieved by the use of chlorination,
ozonation, or electrolytic decomposition.
Alternatively, hydrogen peroxide may be employed to remove
cyanide from mill effluents by oxidation according to the
equation
E2O2 + CN- > H2O + CNQ-
This process which is implemented in a DuPont patent among
others, quantitatively converts cyanide to the much less
toxic cyanate, but does not provide complete reaction to
carbon dioxide and nitrogen.
Aeration in ponds can be interrupted by winter ice cover and
cyanide concentrations above acceptable levels may occur.
One molybdenum operation is experimenting with a cyanide
removal process that uses hydrogen peroxide to supplement
aeration in winter. Thirty percent #202 is gravity-fed from
barrels via stainless steel needle values, to the tailings
decant in a baffled flume that provides intimate mixing.
Tailings decant is retained for several hours before
discharge. Total cyanide concentrations have been reduced
by 30 to 40 percent with dosage ratios of H2p£ to CN of up
to 100 on a weight basis. The process is~"expected to be
more effective in treating free cyanide ion and unstable
cyanide complexes than the stable heavy metal cyanide
complexes that are typically present in decant water from
these operations. Ubiquitous iron-cyanide complexes, for
example, are not oxidized significantly by hydrogen
peroxide. This may explain why H2O.2 treatment appears to
have limited effectiveness as gauged by total cyanide
analysis.
Effective and proper use of chlorination or ozonation should
result in complete destruction of cyanide in mill treatment
systems. At locations where very low levels are encountered
in wastewater streams, aeration devices, auxiliary ponds, or
long retention times may provide removal to below acceptable
levels.
Ammonia used in a solvent extraction and precipitation
operation at one milling site is removed from the mill waste
stream by air stripping. The countercurrent-flow air
stripper used at this plant operates with a pH of 11 to 11.7
and an air/liquid flow ratio of 0.83 cubic meter of air per
liter water (110 cubic feet of air per gallon of water).
Seventy-five percent removal of ammonia is achieved.
450
-------
reducing total nitrogen levels for the mill effluent to less
5 mg/1, 2 mg/1 of which is in the form of nitrates. Ammonia
may also be removed from waste streams through oxidation to
nitrate ty aeration—or, more rapidly, by ozonation—or use
of chemical oxidants, although these procedures are less
desirable due to the impact of nitrates on the receiving
water.
The removal of a variety of COD-producing pollutants from
effluent streams by oxidation in the tailing ponds and/or
delivery lines is evident in data from visited sites. Where
high reagent dosages or other process factors lead to
elevated effluent COD levels, aeration or the use of
stronger oxidants may be of value. In general, the use of
strong oxidants in the tailing pond will be highly
undesirable, since the oxidation of sulfide minerals in the
tails can lead to increased acid production and greater
solubility of ore constituents, including heavy metals.
Aeration will be best practiced in other impoundments also.
Adsorption
Activated carbon is a sorptive material characterized by
high surface area within its internal pore system. Pores
generally range from 10 to 100 Angstrom units (0.001 to 0.01
micrometer), and surface areas of up to 1000 square
meters/gram are considered normal for carbons of this type.
Due to the dimensions of -the pores, to the highly convoluted
internal surface (and, thus, very high surface area), and to
the residual organic contents of carboxyic, carbonyl, and
hydroxyl compounds, activated carbon exhibits adsorptive,
absorptive, and slight residual ion-exchange capabilities.
In contrast to alumina, silica gel, and other adsorbents,
however, activated carbon exhibits a relatively low affinity
for water, compounds which are readily removed by activated
carbon include aromatics, phenolics, chlorinated
hydrocarbons, surfactants, organic dyes, organic acids,
higher-molecular-weight alcohols, and amines. Current
applications of this material also center around the control
and removal of color, taste, and odor components in water.
Activated carbon has been shown to significantly reduce
concentrations of a variety of inorganic salts, including
most heavy metals. Lead concentrations have been reduced
from 100 mg/1 to 0.5 mg/1 (Reference 48). Reports of Hg, V,
Cr, Pb, Ni, Cd, Zn, Fe, Mn, Ca, Al, Ei, Ge, As, Ba, Se, and
Cu removal have appeared in the literature—most often, as
results of laboratory scale treatment (References 49 and
45).
451
-------
In addition to use in tertiary sewage treatment, activated
carbon has found a variety of industrial-waste applications.
At one facility, phenols are removed from 600 cubic meters
(150,000 gallons) per day of chemical plant wastewater
containing 62,000 mg/1 of total dissolved solids (Reference
50) . Influent and effluent levels for this treatment
facility are 100 mg/1 and less than 1 mg/1 of phenol,
respectively. As in this operation, carbon may be
regenerated in a furnace with approximately 95-percent
carbon recovery to reduce materials cost for the operation.
In addition to the economics of operation dictating
regererative processes, recovery of metal values usir.g t'r.e
principles of this treatment is possible. Some indication
of the economic success of this approach may be gained from
the reported viability of the "resin-in-pulp" or "carbon-in-
pulp" process employed at mill U105 in the gold-recovery
circuit. In this case, cyano-complexes of gold (and,
probably, other metals) are reversibly adsorbed from
alkaline solution by activated carbon. Activated-carbon
treatment of acid mine water has been used for iron (+2)
removal (Reference 51).
The application of carbon adsorption, or adsorption by other
materials (such as peat), to mining and milling wastewater
is more likely to be limited by cost than by technical
feasibility. Removal of flotation or solvent-extraction
reagents from waste streams may be practical in some
operations, if waste streams are segregated. Carbon
adsorption could be an important factor in achieving a high
degree of water recycle in flotation mills where reagents or
decomposition products in the feed water would interfere
with processing.
Other Adsorption Methods. While activated carbon is one
specific adsorbent used for wastewater treatment, there are
many additional materials which show varying adsorptive
capacities for wastewater constituents. Many of these
candidate sorbing media have been evaluated only in a
preliminary fashion under full scale conditions, and few of
these have been evaluated with reference to behavior in
actual mine/mill effluents.
Reported adsorbing species include tailing materials
(Reference 52), waste wool (Reference 53) , silica gel,
alumina, hydrous zirconium oxide (Reference 5U) , peat moss
(Reference 55), hydrous manganese oxides (Reference 56), and
others. The sorptive capacity of various soils is currently
under study in conjunction with increased utilization of
452
-------
spray irrigation as a method of wastewater disposal
(Reference 57).
To date, little experience in large-scale wastewater
disposal involving waters similar to mine/mill effluents has
been reported for land disposal by spray irrigation.
Capital costs, operating costs, and performance experience
with municipal, food-industry, and paper-industry waste
disposal, however, suggest the potential desirability of
this procedure (Reference 58). Any spray-irrigation
disposal of mine/mill wastes must be preceded by settling
systems or other treatments to reduce the suspended-solid
load.
Ion Exchange
Ion exchange is basically a process for removal of various
ionic species in or on fixed surfaces. During the fixing
process, ions in the matrix are exchanged for soluble ionic
species. Cationic, anionic, and chelating ion exchangers
are available and may be either solid or liquid. Solid ion
exchangers are generally available in granular, membrane,
and bead forms (ion-exchange resins) and may be employed in
upflow or downflow beds or columns, in agitated baskets, or
in cocurrent- or countercurrent-flow modes. Liquid ion
exchangers are usually employed in equipment similar to that
employed in solvent-extraction operations (pulsed columns),
mixed settlers, rotating-disc columns, etc.). In practice,
solid resins are probably more likely candidates for end-of-
pipe wastewater treatment, while either liquid or solid ion
exchangers may be utilized in internal process streams.
Individual ion-exchange systems dc not generally exhibit
equal affinity or capacity for all ionic species (cationic
or anionic) and, so, may not be suited for broad-spectrum
removal schemes in wastewater treatment. Their behavior and
performance are usually dependent upon pH, temperature, and
concentration, and the highest removal efficiencies are
generally observed for polyvalent ions. In wastewater
treatment, some pretreatment or preconditioning of wastes to
adjust suspended solid concentrations and other parameters
is likely to be necessary.
Progress in the development of specific ion-exchange resins
and techniques for their application has made the process
attractive for a wide variety of industrial applications in
addition to water softening and deionization. It has been
used extensively in hydrometallurgy—particularly, in the
uranium industry—and in wastewater treatment (where it
453
-------
often has the advantage of allowing recovery of marketable
products). This is facilitated by the requirement for
periodic stripping or regeneration of ionic exchangers. If
regeneration produces a solution waste, its subsequent
treatment must be considered.
Table VII-2 shows different types of ion-exchange resins and
the range of conditions and variety of purposes for which
they are employed.
Disadvantages of using ion exchange in treatment of mining
and milling wastewater are relatively high costs, somewhat
United resin capacity, and insufficient specificity—
especially, in cationic exchange resins for some applica-
tions.
Although it is suitable for complete deionization of water,
ion exchange is generally limited in this application, by
economics and resin capacity, to the treatment of water con-
taining 500 mg/1 or less of total dissolved solids. Since
TDS levels in mining and milling effluents are often higher
than this level, application of ion exchange to the economic
reduction of total dissolved solids at high flow rates must
be evaluated.
For recovery of specific ions or groups of ions (e.g.,
divalent heavy-metal cations, or metal anions such as
molybdate, vanadate, and chromate), ion exchange is
applicable to a much broader range of solutions. This use
is typified by the recovery of uranium from ore leaching
solutions using strongly basic anion-exchange resin. As
additional examples, one may consider the commercial
reclamation of chromate plating and anodizing solutions, and
the recovery of copper and zinc from rayon-production
wastewaters (Reference 59). Chromate plating and anodizing
wastes have been purified and reclaimed by ion exchange on a
commercial scale for some time, yielding economic as well as
environmental benefits. In tests, .chromate solutions
containing levels in excess of 10 mg/1 chromate, treated by
ion exchange at practical resin loading values over a large
number of loading elution cycles, consistently produced an
effluent containing no more than 0.03 mg/1 of chromate.
High concentrations of ions other than those to be recovered
may interfere with practical removal. Calcium ions, for
example, are generally collected along with the divalent
heavy-metal cations of copper, zinc, lead, etc. High
calcium ion concentrations, therefore, may make ion-exchange
removal of divalent heavy-metal ions impractical by causing
HSU
-------
TABLE VII-2. PROPERTIES OF ION EXCHANGERS FOR
METALLURGICAL APPLICATIONS
DESIRED
CHARACTERISTIC
CHEMICAL
STABILITY TO:
PHYSICAL STABILITY FOR:
Acids
Alkalies
Oxidation
Temperature
Organic Solvents
Removal of weak
acids
Removal of strong
acids
High regeneration
efficiency
High capacity
High porosity
Hydrogen exchange
at low pH
Salt splitting
pH range (operating)
GENERALLY RECOMMENDED APPLICATION
CATION EXCHANGERS
Inorganic
Zeo-Dur
•
6.2 to
8.7
Decalso
•
•
•
6.9 to
7.9
Organic
Sulfonated
Coal
Zeo-Karb
•
•
•
•
0 to
11
Resins
Permutit Q
•
•
•
•
•
•
•
0 to
13
Car-
boxylic
Resin
Permutit H-70
•
•
•
•
•
•
3.5 to
12
ANION EXCHANGERS
Weakly
Basic
Gran-
ular
De-Acidite
•
•
•
•
•
•
0 to
12
Bead
Permutit W
•
•
•
•
•
•
0 to
13.9
Strongly
Basic
Gran-
ular
Permutit A
•
•
•
•
•
e
0 to
13.9
Bead
(A
•*
£
•
•
•
•
•
•
•
••M^WWBHBM
•
0 to
13.9
SOURCE; Reference 54
455
-------
rapid loading of resins and necessitating unmanageably large
resin inventories and/or very frequent elution steps. Less
difficulty of this type is experienced with amion exchange.
Available resins have fairly high selectivity against the
common anions, such as Cl (-) and SOff(-2). Anions adsorbed
along with uranium include vanadate, molybdate, ferric
sulfate anionic complexes, chlorate, cobalticyanide, and
polythionate anions. Some solutions containing molybdate
prove difficult to elute and have caused problems.
Ion-exchange resin beds may be fouled by particulates, pre-
cipitation within the beds, oils and greases, and biological
growth. Pretreatment of water, as discussed earlier, is
therefore, commonly required for successful operation. Gen-
erally, feed water is required to be treated by coagulation
and filtration for removal of iron and manganese, CO2,, H2_S,
bacteria and algae, and hardness. Since there is some lati-
tude in selection of the ions that are exchanged for the
contaminants that are removed, post-treatment may or may not
be required.
Since, in many cases, calcium is present in ore mining and
milling wastewater in appreciably greater concentrations
than are the heavy-metal cations whose removal to low levels
is sought, use of ion exchange in that mode would be
expensive and little advantage would be offered over lime or
sulfide precipitation. For the removal of anions, however,
the relatively high costs of ion-exchange equipment and
resins may be offset partially or totally by the recovery of
a marketable product. This has been demonstrated in the
removal of uranium from mine water. The removal of
molybdate ion from ferroalloy-ore-milling wastewater has
been investigated, with promising results, in a pilot-plant
study. Treating raw wastewater containing up to 24 mg/1 of
molybdenum, the pulsed-bed ion-exchange pilot plant produced
effluents consistently containing less than 2 mg/1.
Continuous operation was achieved for extended periods of
time, with results indicating possible breakeven or
profitable operation through sale of the recovered
molybdenum. The application of this technique at any
specific site will depend upon a complex set of factors,
including resin loading achieved, pretreatment required, and
the complexity of processing needed to produce a marketable
product from eluent streams.
The practicality of the ion-exchange process will be
enhanced by practices such as waste segregation, recycle,
etc., which allow the treatment of smaller volumes of more
concentrated solutions. Similar factors apply to the
456
-------
treatment of mining and milling waste streams bearing
vanadate and chromate anions, although prior experience in
ion-exchange recovery of these materials should aid the
development of treatment schemes for such wastes.
Modified Desal Process. A demonstration plant for
generating potable water from acid coal-mine drainage, in
operation since early 1973, treats 3,028 cubic meters
(800,000 gallons) per day of water which contains pollutant
loadings similar to those of acid nine drainage (Reference
60). The plant was originally designed for a capacity of
1,893 cubic meters (500,000 gallons) per day, but it is
expected that the plant's capacity can be further increased
to 3,785 cubic meters (1,000,000 gallons) per day through
use of improved operating techniques.
The Modified Desal Process portrayed in Figure VII-5 is a
variation of a system originally developed to produce
potable water from brackish supplies by means of cation and
anion exchange resins. The primary purpose of ion exchange
in treating acid mine water, however, is to remove sulfate,
so only an anion-exchange resin is necessary. The process
uses a weak base anion resin in the bicarbonate form to
replace sulfate or other anions. The solution of metal
bicarbonates is aerated to oxidize ferrous iron to the
ferric form and to purge the carbon dioxide gas. The
increase in pH causes iron, aluminum, and manganese to
precipitate as insoluble hydrous oxides. Some calcium and
magnesium carbonates also precipitate. To produce improved
quality water, well within potable limits, lime treatment
precipitates more calcium and magnesium by converting the
bicarbonates into less soluble carbonates.
The exhausted resin is regenerated with ammonium hydroxide,
which converts the resin to the free-base form.
Introduction of carbon dioxide converts the resin back to
the bicarbonate form, and the regenerated solution of
ammonium sulfate is processed to recover the ammonia through
lime addition. The resultant calcium sulfate is transported
to mine pits for disposal. Regeneration occurs after about
18 hours of operation, and the plant currently utilizes the
original ion-exchange resin.
Operating data for the plant are shown in Table VII-3. It
is felt that this system, or a modification thereof, might
provide effective removal of sulfate and dissolved solids in
the ore mining and dressing industry.
457
-------
Figure VI1-5. DIAGRAM OF MODIFIED DESAL PROCESS
RECYCLE
FROM
MINE '
A
1
1
SETTLING
BASINS
1
1
IRON
MANGANESE
HO ALUMINUM
1
I
1
1
1
CALCIUM AND
MAGNESIUM
GRAVITY
FILTERS
1
1
T
TuReioirr
^ PRODUCT
WATER
LEGEND
MAIN PROCESS
ADDITIONS OR LOSSES
BEGINS RATION PROCESS
SOURCE: R«f«r«nc« 61
458
-------
TABLE VII-3. ANALYTICAL DATA FOR MODIFIED DESAL PROCESS
PARAMETER
pH
Total hardness (CaCO-j)
TDS
Calcium (CaCOg)
Magnesium (CaCOg)
Iron
Sulfate
CONCENTRATION (mg/£ )
RAW WASTEWATER
3.7 •
395
1,084
295
100
101
648
EFFLUENT WATER
9.5"
184
284
85
99
0.2
192
'Value in pH units
459
-------
Present operating costs for water produced at the
Phillipsburg, Pennsylvania, plant are $0.40 to 0.50 per 3.8
cubic meters (1,000 gallons) of water. However, a
considerable reduction in cost might be achieved for the
mining industry for two reasons. The first is that the
demonstration plant contains much instrumentation and many
features that would be unnecessary in a facility designed
merely for production. Secondly, integration of the ion-
exchange system with presently existing lime-neutralization
plants could eliminate the necessity for many features of
the Modified Desal Process system.
Although the cost for treating 3.8 cubic meters (1,000
gallons) of raw mine drainage appears favorable, volumes in
excess of 57,000 cutic meters (15,000,000 gallons) of
drainage generated daily at many facilities require a
substantial total investment in time, material resources,
and energy. Also, individual treatment plants with design
capacities of up to 34,065 cubic meters (9,000,000 gallons)
per day would necessitate the installation of multiple ion-
exchange units at most discharge outfalls. This
configuration would greatly decrease cost effectiveness for
a treatment aimed specifically at removing sulfate and
dissolved solids.
Ultrafiltration and Reverse Osmosis
Ultrafilteation and reverse osmosis are similar processes in
which pressure is used to force water through membranes
which do not allow passage of contaminants. They differ in
the scale of contaminants passed and in the pressures
required. Ultrafiltration generally retains particulates
and materials with a molecular weight greater than 500,
while reverse-osmosis membranes generally pass only
materials with a molecular weight below 100. (Sodium
chloride, although below a molecular weight of 100, is
retained, allowing application to desalinization.)
Pressures used in ultrafiltration generally range from 259
to 517 cm of Hg (50 to 100 psi), while reverse osmosis is
run at pressures ranging from 2,068 to 9,306 cm of Hg (400
to 1,800 psi) .
Ultrafiltration has been applied on a significant commercial
scale to the removal of oil from oil emulsion, yielding a
highly purified water effluent and an oil residue
sufficiently concentrated to allow reuse, reclamation, or
combustion. Equipment is readily available, and present-day
membranes are tolerant of a broad pH range. Application of
ultrafiltration to mining and milling waste streams, where
460
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high dosages of oils are used in flotation—as at a formerly
operated manganese mill—may provide a practical technique
for removing these waste components, possibly allowing reuse
as well.
Reverse osmosis (RO) is conceptually similar to ultrafiltra-
tion. It also involves the application of an external
pressure to a solution in contact with a semipermeable
membrane to force water through the membrane while excluding
both soluble and insoluble solution constituents. In its
rejection of soluble constituents, reverse osmosis performs
a water-treatment function not fulfilled by ultrafiltration
systems under simple operating conditions.
Reverse osmosis is considerably less tolerant of input-
stream variations in conditions and requires, in general,
considerable pretreatment. Concentration of wastes is
generally limited by saturation of solutions and the
formation of precipitates, which can decrease the
effectiveness of the apparatus. As a result, residual
volumes of waste in the mining and milling industry would,
in many cases, be unmanageably large. A pilot-plant
operation has been run on mine drainage streams, and
production of a high-quality water effluent has been shown
to be technically feasible. Pretreatment requirements,
costs, and the problems of disposal of residual wastes make
the practicality and economic achievability important con-
siderations.
Reverse osmosis has been demonstrated capable of rejecting
heavy-metal species from purified water streams with a high
degree of efficiency (Table VII-4). Reverse-osmosis systems
have been evaluated for acid mine water treatment
(References 62 and 63). Related studies have been conducted
with metal finishing effluents (Reference 64). In most
instances, pretreatment of water, and conditioning with
respect to pH, temperature, and suspended-solid levels, is
necessary for reverse-osmosis module use. Membrane lifetime
and constancy of efficiency are both adversely affected by
inadequate treatment of waters prior to membrane contact.
In general, laboratory performance of reverse-osmosis
systems has shown somewhat higher purification efficiencies
than have been observed in pilot-plant operations (Reference
U5). The present state-of-the-art with regard to RO
technology indicates that details of extrapolation of
laboratory and current pilot-plant data to full-scale
operation need to be worked out. Data on membrane lifetime,
operating efficiency, rejection specificity, and other
factors remain to be more fully quantified.
461
-------
TABLE VII-4. REJECTION OF METAL SALTS BY REVERSE-
OSMOSIS MEMBRANES
PARAMETER
Iron
Magnesium
Copper
Nickel
Chromium (hexavalent)
Strontium
Cadmium
Silver
Aluminum
TYPICAL REJECTION PERCENT
99
98
99
99.2
97.8
99
98
96
99
SOURCE: Reference 47
462
-------
High-Den si tv-Sludqe Acid Neutralization
The conventional lime neutralization of acid or mine wastes
usually leads to the formation of low-density sludges which
are difficult to dewater (floes). The use of ground lime-
stone avoids this problem but does not allow for the attain-
ment of pH levels necessary to effectively remove such
metals as zinc and cadmium. A process which utilizes
extensive recycle of the previously precipitated sludge
allows the attainment of sludges of much higher density,
thus allowing more rapid sedimentation of the sludges
ultimately produced and easing solid-disposal problems.
Solvent Extraction
Solvent extraction is a widely utilized technique for the
separation and/or concentration of metallic and nonmetallic
species in the mineral processing industry. It has been
applied to commercial processing of uranium, vanadium, tung-
sten, thorium, rhenium, rare earths, beryllium, columbium,
copper, zirconium, molybdenum, nickel, boron, phosphoric
acid, and others (References 65 and 66). Reagent-processing
equipment for this technique is highly developed and
generally available (Reference 67). It is anticipated that
such equipment would require modification to be applicable
to treating the low levels of soluble metals in most waste
streams. Pretreatment and post-treatment of waters treated
by this technique would probably be required to control
influent pH, suspended solids, and other parameters, as well
as effluent organic levels. It is likely that this
treatment strategy may be most applicable in internal
process streams or as an add-on for the recovery of values
from waste-concentration streams such as distillate or
freeze residues, reverse-osmosis brines, etc.
Because of the speculative nature of solvent extraction as
applied to wastewater treatment, the unknown costs of rea-
gents, and possible pretreatment/post-treatment demands,
accurate treatment or capital costs for this option do not
appear readily derivable at this time.
Evaporation and Distillation
Evaporation may be employed as a wastewater-treatment tech-
nique in a variety of ways:
(1) Total evaporation of wastewater may produce solid
residues and eliminate effluent water discharge.
463
-------
(2) Concentration of wastewater by evaporation may
balance dilution by makeup and infiltration water
and allow for an approach to total recycle, thus
minimizing discharge volume. The buildup of detri-
mental species upon evaporation will normally
require a bleed stream from the evaporation system,
thus precluding total water recycle. A bleed
stream, of course, might be handled by total
evaporation, rather than by discharge to a
waterway.
(3) Concentration by evaporation may allow subsequent
removal of concentrated wastewater components to
acceptable levels for smaller-volume discharge or
reuse.
(4) Ultimately, complete distillation of wastewater may
allow the almost total reuse or recycle of
contained water, while rendering discharge unnec-
essary and allowing potential recovery of values
from nonvolatile residues. In the absence of
recoverable values, disposal of sludge resulting
from distillation might become a problem of sub-
stantial magnitude. The presence of volatile
wastes in the effluent may require additional
treatment of distillate to achieve adequate quality
for some uses.
Energy sources for evaporation may be artificial (steam, hot
gases, and electricity) or natural (solar, geothermal,
etc.). In present practice, many of the mining and milling
operations in the Western and Southwestern United States
employ solar evaporation as a principal means of water
treatment. Evaporative losses of water at some
installations may exceed 7,572 cubic meters (2,000,000
gallons) per year for each 0.4 hectare (1 acre) of
evaporative surface; with adequate surface acreage, this
loss may allow for zero-effluent-discharge operation. At
present, this evaporated water is not collected for reuse at
these operations.
A multistage flash-distillation process has been applied to
treat acid mine drainage (from a coal mine) in a pilot plant
(Reference 68). The process is mechanically complex but
results in a solid residue and essentially pure water, suit-
able for human consumption. This approach to pollution con-
trol involves the use of considerable energy associated with
vaporizing vast volumes of water. Its technical
applicability to treating mine water has been demonstrated,
but it is not clear that organic wastes potentially present
464
-------
in mill effluents would be successfully controlled by such a
process.
Techniques for Reduction of Wastewater Volume
Pollutant discharges from mining and milling sites may be
reduced by limiting the total volume of discharge, as well
as by reducing pollutant concentrations in the waste stream.
Volumes of mine discharges are not, in general, amenable to
control, except insofar as the mine water may be used as
input to the milling process in place of water from other
sources. Techniques for reducing discharges of mill
wastewater include limiting water use, excluding incidental
water from the waste stream, recycle of process water, and
impoundment with water lost to evaporation or trapped in the
interstitial voids in the tailings.
In most of the industry, water use should be reduced to the
extent practical, because of the existing incentives for
doing so (i.e., the high costs of pumping the high volumes
of water required, limited water availability, and the cost
of watertreatment facilities). Incidental water enters the
waste stream primarily through precipitation directly and
through the resulting runoff influents to tailing and
settling ponds. By their very nature, the water-treatment
facilities are subject to precipitation inputs which, due to
large areas, may amount to substantial volumes of water.
Runoff influxes are often many times larger, however, and
may be controlled to a great extent by diversion ditches and
(where appropriate) conduits. Runoff diversion exists at
many sites and is under development at others.
Recycle of process water is currently practiced primarily
where it is necessary due to water shortage, or where it is
economically advantageous because of high water costs.
Recycle to some degree is accomplished at many ore mills,
either by reclamation of water at the mill or by the return
of decant water to the mill from the tailing pond or
secondary impoundments. Recycle is becoming, and will
continue to become, a more frequent practice. The benefits
of recycle in pollution abatement are manifold and
frequently are economic as well as environmental* By
reducing the volume of discharge, recycle not only reduces
the gross pollutant load, but also allows the employment of
abatement practices which would be uneconomic on the full
waste stream. Further, by allowing concentrations to
increase, the chances for recovery of waste components to
offset treatment cost—or, even, achieve profitability—are
substantially improved. In addition, costs of pretreatment
465
-------
of process water--and, in some instances, reagent use—may
be reduced.
Recycle of mill water almost always requires some treatment
of water prior to its reuse. In many instances, however,
this may entail only the removal of solids in a thickener or
tailing basin. This is the case for physical processing
mills, where chemical water quality is of minor importance,
and the practice of recycle is always technically feasible
for such operations. In flotation mills, chemical
interactions play an important part in recovery, and
recycled water can, in some instances, pose problems. The
cause of these problems, manifested as decreased recoveries
or decreased product purity, varies and is not, in general,
well-known, being attributed at various sites and times to
circulating-reagent buildup, inorganic salts in recycled
water, or reagent decomposition products. Experience in
arid locations, however, has shown that such problems are
rarely insurmountable. In general, plants practicing bulk
flotation on sulfide ores can achieve a high degree of
recycle of process waters with minimal difficulty or process
modification. Complex selective flotation schemes can pose
more difficulty, and a fair amount cf work may be necessary
to achieve high recovery with extensive recycle in such a
circuit. Numerous examples where this has been achieved may
be cited (Reference 69). Problems of achieving successful
recycle operation in such a mill may be substantially
alleviated by the recycle of specific process streams within
the mill, thus minimizing reagent crossover and degradation.
The flotation of non-sulfide ores (such as scheelite) and
various oxide ores using fatty acids, etc., has been found
to be quite sensitive to input water quality. Attempts at
water recycle in such operations have posed severe problems,
and successful operation may require a high degree of
treatment of recycle water. In many cases, economic
advantage may still exist over treatment to levels which are
acceptable for discharge, and examples exist in current
practice where little or no treatment of recycle water has
been required.
Technical limitations on recycle in ore leaching operations
center on inorganic salts. The deliberate solubilization of
ore components, most of which are not to be recovered, under
recycle operations can lead to rapid buildup of salt loads
incompatible with subsequent recovery steps (such as solvent
extraction or ion exchange). In addition, problems of
corrosion or sealing and fouling may become unmanageable at
some points in the process. The use of scrubbers for air-
pollution control on roasting ovens provides another
466
-------
substantial source of water where recycle is limited. At
leaching mills, roasting will be practiced to increase
solubility of the product material. Dusts and fumes from
the roasting ovens may be expe'cted to contain appreciable
quantities of soluble salts. The buildup of salts in
recycled scrubber water may lead to plugging of spray
nozzles, corrosion of equipment, and decreased removal
effectiveness as salts crystallizing out of evaporating
scrubber water add to particulate emissions.
Impoundment is a technique practiced at many mining and
milling operations in arid regions to reduce point
discharges to, or nearly to, zero. Its successful
employment depends on favorable climatic conditions
(generally, less precipitation than evaporation, although a
slight excess may be balanced by process losses and
retention in tailings and product) and on availability of
land consistent with process-water requirements and seasonal
or storm precipitation influxes. In some instances where
impoundment is not practical on the full process stream,
impoundment and treatment of smaller, highly contaminated
streams from specific processes may afford significant
advantages.
Electrodialvsis
Electrodialysis is fundamentally similar to both reverse
osmosis and ultrafiltration to the extent that it employs
semipermeable membranes to allow separation of soluble
cationic and anionic impurities from water. An imposed
electrical field is used to provide a driving force for ion
migration, in analogy to either osmotic or external pressure
in reverse-osmosis, dialytic, or ultrafiltration Systems.
Electrodialysis is generally employed in the treatment of
waters containing less than 5,000 to 10,000 mg/1 of
dissolved solids to achieve final levels of less than 500
mg/1 (Reference 44). Applications have been reported in
desalinization of seawater involving feed water containing
38,000 mg/1 chloride and producing a product water
containing 500 mg/1 chloride (Reference 54).
To date, electrodialysis has not been employed in large-
scale operations within the mining/milling industry segments
reviewed and studied in this program. The potential for
isolation and recovery of byproduct or waste values exists
but has not been confirmed.
467
-------
Freezing
This process depends on the formation of pure ice crystals
from the contaminated solution being treated. Results of
freezing experiments on acid mine-drainage samples (from a
coal mine) indicate that suspended solids act as
condensation nuclei and, if present, are entrained with the
"pure" ice obtained. Once solids have been removed, of
course, the mine drainage may still contain other
contaminants.
Experimentally, agitation and slow freezing rates have
allowed reductions in dissolved materials in the range of 35
to 90 percent (Reference U5) .
This process results in a concentrated stream, which still
requires treatment. It has a theoretical advantage over
distillation because only about one-sixth of the energy
should be required. Laboratory-scale experiments indicate
it may be a feasible treatment technique for mine and mill
water treatment, but it has not been fully tested.
Biological Treatment
The ability of various biota--both flora and fauna—to
assimilate soluble constituents from contacting waters is
being documented with increasing frequency. In general,
these studies have considered the undesirability of such
assimilations, rather than viewing them from the standpoint
of potential water-treatment options or systems. If trace
or toxic constituents can be metabolized, detoxified, or
fixed by various organisms, the periodic removal of
organisms containing concentrates of these materials may be
a viable removal mechanism.
The use of this technique at one facility visited involves a
combination of sedimentation ponds and biological treatment
in the form of meanders. The meander system is an
artificial system designed to contain—and, thereby,
control—excessive algal growth and the associated heavy
metals which are trapped and assimilated by the algae
(Reference 70). The algal growth occurs naturally and was a
problem associated with the discharge prior to installation
of the present system. The system was designed as a series
of broad, shallow, rapidly flowing meanders, which increase
the length of the treatment section and encourage the growth
of algae before discharge, while simultaneously trapping any
suspended heavy metals. To prevent the algae and the
associated heavy metals from escaping the system, an
additional final sedimentation pond is placed at the end of
the system.
468
-------
The system can be effective if sufficient land is available
to allow the construction of an adequate meander system, and
if the climate is such that algae growth is not precluded
during parts of the year. These conditions effectively
prevent widespread application of this treatment technique.
EXEMPLARY TREATMENT OPERATIONS BY ORE CATEGORY
The manner in which ore mine and mill operators have
approached the design and construction of treatment and
control facilities varies from quite simple to somewhat
sophisticated (utilizing recycling, zero-discharge
operations). To attain extensive recycling or zero
discharge, extensive process changes and/or redesign have
often been necessary. Performance of the many vaired
operations used in each ore category varies with the
operating characteristics of the facility, the ore
mineralogy, and other factors. Descriptions, by ore
category, of the treatment and control processes used in the
ore mining and dressing industry and the consequent
treatment levels attained are included here to provide a
more complete explanation and examination of the control and
treatment technology currently in use.
Iron Ore
This discussion includes examples of mines that have
discharges (Subcategory I), mills which employ physical and
chemical beneficiation and mills which employ only physical
benefication (Subcategory II), and mills using magnetic- and
physical-separation methods (Subcategory III).
Mining Operations. Mine 1105 is an open-pit operation that
accumulates water. Water is pumped directly from the pit to
a settling pond of sufficient volume to remove suspended
solids prior to discharge. No chemical coagulants are used,
because the suspended-solid concentration generally is less
than 10 mg/1. Because this operation produces low levels of
dissolved components, dissolved-solid treatment is
unnecessary. Suspended-solid concentrations after treatment
have been observed to remain low, but historical data
obtained during periods of high rainfall and high pumping
rates are lacking.
Table VII-5 is a compilation of data measured in this study
and by the operators. It can be observed that many of the
parameters measured appear to increase in the effluent
stream after treatment. Measurements made during this study
were confirmed by duplicate industry sample analysis.
469
-------
TABLE VII-5. CHEMICAL CHARACTERISTICS OF SETTLING-POND DISCHARGE AT
MINE 1105
PARAMETER
pH
TSS
TDS
COD
Oil and Grease
Total Fe
Dissolved Fe
Mn
Sulfate
AVERAGE
MINE-DISCHARGE
CONCENTRATION 4mg/£ )
This Study
•
7.4
10
225
9.7
<1
<0.02
< 0.02
0.04
24
Industry
7.9'
6
243
4.5
< 5
-
<0.1
<0.1
—
AVERAGE
SETTLING-POND
DISCHARGE
CONCENTRATION (mg/£)
This Study
7.4*
25
283
13.7
<1
0.1
<0.02
< 0.02
35
Industry
8.0*
8.5
291
15
<5
-
<0.1
<0.1
-
AVERAGE
SETTLING-POND
DISCHARGE
CONCENTRATION
(mg/£)t
8.0*
3.4
—
—
«10)
—
—
-
—
Value in pH units
tHistorieal data
470
-------
Conditions existing at the mine settling pond should be
noted, however. At the mine discharge, an extremely low
flow was encountered, and only intermittent pumping of the
mine was being employed. At the settling-pond discharge,
however, flow conditions were adequate for sampling.
Historical data obtained at this location for nine months
during 1974 show that a range of 1 to 9 (average of 3.4)
mg/1 of TSS was encountered after settling.
Mills Employing Physical and/or Chemical Separations. Iron
beneficiation plant 1109 uses magnetic separation, coupled
with a froth-flotation sequence that removes undesired
silica in the iron concentrate. The processing circuit uses
587 cubic meters <155,000 gallons) of water per minute, with
a recycle rate of 568 cubic meters (150,000 gallons) per
minute. Thickeners, located adjacent to the concentrator,
are used to reclaim water close to the site of reuse so as
to minimize pumping requirements. Superfloc 16, an anionic
polyacrylamide, is added to the thickeners at a rate of 2.5
grams per metric ton (0.0049 pound per short ton) of mill
feed to aid in clarification of the water in the thickeners.
The thickener underflow is pumped to a 850-hectare (2,100-
acre) tailing basin for the sedimentation of the solids.
Mine water is also pumped to the basin. The effluent leaves
the basin after sufficient retention and flows into a creek
at an average rate of 22330 cubic meters (5,900,000 gallons)
per day. Chemical analysis of the wastewater to the tailing
pond (mine and mill water) in comparison to the effluent
water quality and waste loading is given in Table VII-6.
Mills Employing Magnetic and Physical Separation. Mill
1105 is located in the Mesabi Range of Minnesota and is
processing ore of the Biwabik formation. Crude magnetic
taconite is milled to produce a finely divided magnetite
concentrate. The mill's water system is a closed loop
having no point-source discharges to the environment. The
plant processes use 20.4 cubic meters (54,000 gallons) per
minute, with 189 cubic meters (50,000 gallons) per minute
returned from the tailing-thickener overflow and 15.1 cubic
meters (4,000 gallons) per minute returned from the tailing
pond or basin. The tailing thickener accumulates all the
milling-process wastewater containing the tailings. A
nontoxic polyacrylamide flocculant (SuperFloc 16) is added
to the thickener to assist the settling out of solids.
Tailing thickener underflow is pumped to a tailing basin of
470 hectares (1,160 acres), where the solids are settled and
the clear water is recycled back into the plant water-use
system. A simplified water-use sequence is shown in Fioure
VII-6.
471
-------
TABLE VII-6. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTELOADING AT MINE/MILL 1109
PARAMETER
pH
TSS
TOS
COO
Tout ft
Dinolvtd Ft
Mn
SulfM*
Alktlinity
MINE EFFLUENT
CONCENTRATION
InVtl
8.3"
12
308
27.6
0.30
0.02
0.86
37
181
MILL EFFLUENT
CONCENTRATION
(m«/U
8.6"
<5SM
360
13.S
0.04
0.04
-
, 20.7
238
WASTE LOAD
PER UNIT PRODUCT
kg/metric ion
_
1.346
0.88
0.033
0.0001
0.0001
-
0.06
0.68
Ib/ihort ton
—
2.880
1.76
0.066
0.0002
0.0002
-
0.10
1.16
FINAL DISCHARGE
CONCENTRATION
fmo/z)
8.3"
10
222
18.0
0.76
0.44
<0.02
3.6
120
WASTE 1
PER UNIT P
kg/mrtric ton
—
0.02
0.48
0.039
0.0016
0.0010
< 0.00004
0.0076
0.26
.OAO
RODUCT
Ib/ihort ton
—
0.04
O.M
0.076
0.0032
0.0020
0.00008
0.0162
0.62
HISTORICAL
CONCENTRATION-
(mt/i)
7.7"
3.4
-
-
-
0.60
0.06
-
-
Avtrio! of nint »atu«i (Auguit throu«h Octooir 1974)
•
Valu« in pH units.
472
-------
Figure VI1-6. MILL 1105 WATER-USE SYSTEM (ZERO DISCHARGE)
WATER
1
PROCESS
PRODUCT
i •
THICKENING
1 1
OVERFLOW UNDERFLOW
I 1
1
FILTRATION
1 1
CAKE FILTRATE
1 1
1
TO FINAL
PROCESSING
PROCESS
TAILING
""""" i '
THICKENING
UNDERFLOW OVERFLOW
/^SEDIMENTATIONS
Vw^ BASIN ^J
SETTLED CLARIFIED
SOLIDS EFFLUENT
1
t
TO WASTE
473
-------
Copjger Ores
The discussion that follows describes treatment and control
technology in current use in the five sutcategories of the
copper-ore mining and dressing industry.
Mining Operations . Mine water generated from natural
drainage is reused in mining, leaching, and milling
operations wherever possible in the copper mining industry.
Because of an excess of precipitation in certain areas of
the country, a location which is not proximate to a milling
facility, or an inability to reuse the entire amount of mine
wastewater at a particular mill, a discharge may result.
The amounts of precipitation and evaporation thus have an
important influence on the presence or absence of mine-water
discharge.
To avoid discharge, mine effluent may be reused in dump,
heap, or in-situ leaching as makeup water. As a leach
solution, it is acidified (if necessary), percolated through
the waste dump, sent through an iron-precipitation facility,
and recycled to the dump (Figure VII-7).
Large quantities of water are usually needed in the copper
flotation process. Mine-water effluent is used at many
facilities as mill process makeup water. The mine water may
pass through the process first, or it may be conveyed to the
tailing pond, from which it is used for mill flotation with
recycled process water (Figure VII-8). The practice of com-
bining mine water with mill water can create water-balance
difficulties unless the mill circuit is capable of handling
the water volumes generated without a discharge resulting.
The discharge of mine water into a mill process system which
creates an excess water balance and subsequent discharge may
have a detrimental effect on the mine water because of
contamination by mill flotation reagents and residual
wastes. However, in other instances, a benefit has been
realized when mine and mill wastewater is combined for
treatment. For this reason, the optimum wastewater-
treatment scheme adopted must be determined on an individual
basis.
Acid mine water is encountered in the copper mining
industry, and methods of neutralization usually employed
include the addition of lime and limestone. Acid mine water
containing solubilized metals may be effectively treated by
combining the mine water with the mill tails in the mill
tailings pond. The water may be further treated by lime-
clarification and aeration.
H7H
-------
Figure VII-7. CONTROL OF EFFLUENT BY REUSE OF MINE WATER IN LEACHING
(MINE 2122)
EVAPORATION
AND SEEPAGE
— EFFLUENT
3270 m^/day
(864,000 gpd)
STORAGE
RESERVOIR
EVAPORATION
AND SEEPAGE
DUMP LEACH
BED
RECYCLED
BARREN
SOLUTION
r
PREGNANT
SOLUTION
IRON
PRECIPITATION
PLANT
I
CEMENT
COPPER
TO
STOCKPILE
475
-------
Figure VII-8. CONTROL OF MINE-WATER EFFLUENT BY REUSE IN THE
CONCENTRATOR (MINE/MILL 2119)
MILL/
CONCENTRATOR
37.100 m°/day
(9,792.000
gpd)
TAILING
THICKENERS
RECYCLED
'OVERFLOW
RECYCLED
POND
WATER
(NO DISCHARGE)
476
-------
Lime precipitation is also often used to enable the removal
of heavy metals from wastewater by precipitation as
hydroxides. Tables VII-7 and VII-8 show examples of the use
of lime precipitation for treatment of mine water at two
locations of mine 2120. The use of this treatment
technology is demonstrated to effectively reduce several
heavy metals of interest.
Various techniques are employed to augment the use of lime
neutralization. Among these are secondary settling ponds,
clarifier tanks, or the addition of flocculating agents
(such as polyelectrolytes) to enhance removal of solids and
sludge before discharge. Often, readjustment of the pH is
necessary after lime treatment. This can be accomplished by
addition of sulfuric acid or by recarbonation. The use of
sulfide precipitation may be necessary in some instances for
further removal of metals such as cadmium and mercury.
Mine Employing Hvdrometallurgical Process. Acid solutions
employed in dump, heap, and in-situ leaching are recycled in
this subcategory of the copper industry, allowing the
recovery of copper in the iron precipitation plant. Water
is added to replace losses due to evaporation and seepage.
Acid is added to control pH. Table VII-9 lists the
operations surveyed and their control of acid solutions.
Only one operation surveyed discharges a small amount of
"bleed water" to surface waters.
Control of seepage and collection of acid-leach solution are
sometimes aided by the construction of specially prepared
surfaces, upon which heaped ores are placed for leaching.
These surfaces may be constructed of asphalt, concrete, or
plastic.
One facility currently bleeds the acid-leach solution and
treats the bleed by neutralization and precipitation with
alkaline (limed) tailings from the mill. The treated water
flows into the tailing pond for settling and is subsequently
recycled with the decant water to the mill.
Treatment of the leach solutions used in this subcategory is
sometimes necessary for control of dissolved solids, which
build up during recycling. Holding ponds are constructed to
retain leach solutions for a sufficient time to allow the
iron salts to precipitate from solution and settle, before
the solution is recycled to leach beds. In conjunction
with, or in place of holding ponds, pH control aids in pre-
venting iron salts from precipitating in pipes or in the
leach dump.
U77
-------
TABLE VI1-7. CONCENTRATION OF PARAMETERS PRESENT IN RAW WASTEWATER AND
EFFLUENT FOLLOWING LIME PRECIPITATION AT MINE 2120B
PARAMETER
PH
TDS
TSS
Oil and Grease
Cd
Cu
As
Zn
Fe
Ni
Hg
Pb
CONCENTRATION (mg/1 )
RAW WASTEWATER
(CONTRACTOR DATA7)
6.1 to 10.8*
2,200
131
<1
0.13
2.6
0.02
12
7.5
0.13
0.0015
<0.1
TREATED WASTEWATER
CONTRACTOR
DATA*
10.9 to 12.7*
3,000
32
<1
< 0.04
0.18
<0.02
0.35
0.7
< 0.05
0.0007
<0.1
COMPANY MONITORING DATA**
MEAN
_
—
12
—
0.01
0.07
0.004
0.16
0.11
—
0.0003
0.01
RANGE
_
-
7 to 46
-
< 0.01 to 0.03
0.04 to 0.61
0.001 to 0.033
0.08 to 1.0
0.09 to 0.68
—
< 0.0002 to 0.0006
< 0.01 to 0.01
* Value in pH units.
t Average of one grab sample and two 24-hour composite samples.
"For period June 1975 through May 1976. Mean values are averages of monthly mean data; range is lowest
monthly average and highest single-day concentrations observed.
478
-------
TABLE VII-8 CONCENTRATION OF PARAMETERS PRESENT IN RAW WASTEWATER AND
EFFLUENT FOLLOWING LIME PRECIPITATION AT MINE 2120C
PARAMETER
PH
TDS
TSS
Cu
Cd
As
Zn
Fe
Hg
Pb
CONCENTRATION (mg/i )
RAW WASTEWATER
(CONTRACTOR DATA")
6.9
450
2,075
18
0.09
0.05
5.1
84
0.0001
<0.1
TREATED WASTEWATER
CONTRACTOR
DATA*
8.5
—
26
0.14
< 0.04
< 0.02
0.21
0.46
0.0001
< 0.1
COMPANY MONITORING DATA1"
MEAN
—
—
7
0.26
0.01
0.004
0.25
0.58
0.0003
0.01
RANGE
—
—
3 to 30
0.05 to 0.51
< 0.01 to 0.01
< 0.001 to 0.011
0.03 to 0.62
0.08 to 1.13
< 0.0002 to 0.0005
< 0.01 to 0.03
* Average of one grab sample (collected October 1974) and two 24-hour composites (collected May 1975).
'•Value in pH units.
t For period June 1975 through May 1976. Mean data are averages of single monthly analyses; range data represent
range of single monthly analyses.
479
-------
TABLE VI1-9. DUMP, HEAP, AND IIM-SITU LEACH-SOLUTION CONTROL
AND TREATMENT PRACTICE (1973)
PLANT
2101
2102
2103
2110
2116
2118
2123
2107
2108
2122
2124
2125
2104
2120
CONTROL
Zero discharge
Zero discharge
Zero discharge
99.4% recycle
98.7% recycle
TREATMENT
Recycle without treatment
20% to evaporation ponds
All effluent circulated through
holding ponds or reservoirs
None
Bleed is limed and settled in
tailing pond
DISCHARGE
None
None
None
654m3/day(avg)*
2551 m3/day (avg)"»
totalling pond (not
discharged)
•Inadequate pumps. Operation required to attain zero discharge by State Regulations in 1977.
•The treated bleed is recycled to the mill with the decant.
480
-------
Evaporation ponds are also employed to accomplish zero dis-
charge of acid-leach bleed solutions.
Mill Employing Vat Leaching for Extraction. Zero discharge
has been reached by all facilities studied (Table VII-10).
Makeup water is required to replace evaporative losses and
the moisture which remains in the discarded, leached ores.
Complete recycling of barren leach and wash solutions is
usually practiced. However, one facility presently reuses
its spent vat-leach solution in a smelter process to achieve
zero discharge.
Mill Employing Concentration by_ Froth Flotation. Mills
employing froth flotation could be divided into two
subcategories of the copper-ore mining and dressing industry
based on climatic conditions such as: (1) mills located in
areas where net evaporation is less than 76.2 cm (30 in.);
and (2) mills located in areas where net evaporation equals
or exceeds 76.2 cm (30 in.). All facilities currently in
operation in group (2) discharge no wastewater effluent.
Process water from froth flotation contains large amounts of
suspended solids, which are normally directed to a large
lagoon to effect settling of these solids. Surface runoff,
such as that resulting from snow melt, heavy-rainfall
events, streams, and drainage, should be conveyed around the
tailing pond, thus preventing runoff water from contacting
process effluents. In this manner, the volume of water
which must be treated or impounded is reduced.
Mill tailing-pond water may be decanted after sufficient
retention time. One alternative to discharge, and an aid to
reducing the amount of effluent, is to reuse the water in
other facilities as either makeup water or full process
water. Usually, some treatment is required for reuse of
this decanted water. Figure VII-9 illustrates the control
of effluent by reuse, as practiced at mill 2124.
The volume of water to be treated in flotation mills can be
effectively reduced, and the quality of the discharge often
substantially improved, by the separation of mine water,
sewage, smelter drainage, refinery wastes, and leach bleed
scl-ation from the tailing-pond circuit. It has been
observed that separation of mine water, with subsequent
treatment and discharge of the mine water only, can allow
mill tailing decant water to be recycled fully. Using
mine/mill 2121 as an example. Figure VH-10 was constructed
to illustrate current practice, as well as alternative
481
-------
TABLE VII-10. SOLUTION-CONTROL PRACTICE IN VAT LEACHING OF COPPER ORE
MILL
2102
2116
2124
2126
CONTROL
100% recycle
100% recycle
100% recycle
Zero discharge
RECYCLE TREATMENT
None
None
None
Spent acid sent to acid plant for
reuse
482
-------
Figure VII-9. CONTROL OF EFFLUENT THROUGH REUSE OF MILL FLOTATION-
PROCESS WATER IN OTHER FACILITIES {MINE/MILL 2124)
5%
TO
ATMOSPHERE
EVAPORATION
20%
TO
ATMOSPHERE
EVAPORATION
u
23.500 mj/d.v
16.200.000 *>dl
34%
54%
•RECYCLE
TRANSFERED-
RECYCLE-
7%
> TRANSFERED-
• RECYCLE
TOTAL
34%
66%
TO
ATMOSPHERE
EVAPORATION
I 61%
i.Xs
TAILING
POND
RETENTION
483
-------
Figure VII-10. REDUCTION IN WASTE POLLUTANT LOAD IN DISCHARGE BY SEPARATION
OF MINEWATER FROM TAILING POND FOR SEPARATE TREATMENT
(MILL 2121)
CURRENT
OTHER
WASTES
MILL
PROCESS
WATER H
(LIMED)
MINE
EFFL
1 ' '
UENT
' 1 '
""X^^^ POND ^}
i
i
EFFLUENT ®
TOTAL WASTE LOAD DISCHARGED AT®
Ptr 24 noun in kg/day (Ib/dayl
Flow
pH
TSS
Oil and Greau
Cu
At
Zn
Ft
Cd
Ni
Hg
Pb
102.000 m3/day (27,000.000 gpd)
8.4'
620 (1.3641
415 (913)
27 (59.41
<8 « 17.6)
S.2 111.41
10.3 (22.71
<2 « 4.41
<5.2 (< 11.41
<0.01 « 0.022)
<10.3 « 22.71
ALTERNATIVE
c
7
MINE 1
{
PROCESS LIME
WATER TREATMENT
__L 1
TAnNn° ^) SETTLING
[ {
| DISCHARGE
(B)
ESTIMATED TOTAL WASTE LOAD DISCHARGED. USING LIME
PRECIPITATION, AT (f)
P»r 24 noun in kg/day lib/day 1
Flow
pH
TSS
Oil and Greait
Cu
Ai
Zn
Ft
Cd
Ni
Hg
Pb
Raw (No Treatment)
3.800 m3/day
(1.000.000 gpdl
7.4*
267 (587)
<4 KB.8I
4 18.8)
<0.3 « 0.661
10.8 (23.8)
<0.4 (
-------
future practice which would result in a reduction of the
waste loads discharged.
Separation of mine water and other wastes from contact with
mill process water is suggested in all cases where pollutant
load and water volume are factors. Not only do these waste
waters contribute to the pollutants present in the tailing-
pond water, but they may dilute the water to be treated or
cause excess water-volume conditions to result which cannot
be handled by recycling.
If sewage plant overflow contributes to the tailing-pond
water volume to the extent that it cannot be accommodated in
recycling, this water should be properly treated and handled
separately.
Smelter and refinery wastes often contribute a heavy load of
dissolved metals to tailing ponds. These wastes can affect
the quality of the decant water, as well as effluent
volumes. It may be necessary to handle wastes from these
sources separately, and/or as recommended under the
appropriate conditions for the Effluent Limitation
Guidelines for the Copper Smelting and Refining Industry.
The most efficient control of the volume and pollutant dis-
charge of mill flotation-process water is to recycle the
excess water which would overflow from the tailing-pond
decant area. Of the 27 major copper mills surveyed, 24 are
known to be recycling all or a portion of their process
water. The impetus for recycling has often been the lack of
an adequate water supply. However, the feasibility of
recycling process water appears to have been considered at
all facilities.
Through the use of diversion ditching, evaporation (when
available) , reservoirs, and separation of other process
water the volume of water to be recycled can be adjusted to
allow'reuse. Treatment of the recycled water is usually
required and may 'include secondary settling, phosphate or
lime addition (for softening), pH adjustment, or aeration.
The majority of copper mills currently operating recycle
their mill process water. Of the remaining facilities that
currently discharge, half are recycling at least 35 percent
of their process water. Treatment of discharged water
consists of settling alkaline wastewater in a tailing pond.
A variety of treatment approaches are currently used in this
subcategory, including:
485
-------
(1) Settling Only
(2) Lime Precipitation and Settling
(3) Lime Precipitation, Settling, Use of
Polyelectrolytes, and Secondary Settling
One operation is currently building a treatment facility
which will include lime precipitation, settling, and
aeration.
Table VII-11 shows the reduction of pollutant concentrations
attained in six mills under different conditions of
recycling, lime addition, and settling. A wide variation in
practice is used to obtain varying degrees of concentration
for waste constituents present in treated wastewater. It
must be noted that only mills 2120, 2121 and 2122 discharge;
the other three mills are achieving zero discharge through
recycle. When the data was obtained, mill 2120 was in the
process of eliminating discharges from the mill; to date
this facility is achieving approximately 90% recycle. Mill
2122 is not providing exemplary treatment.
An exemplary demonstration of waste effluent treatment by
lime precipitation is summarized below. In this system,
three waste streams enter for combined treatment in a
tailing lagoon in the ratio shown. Calculations were based
on waterflow volume.
(mg/1) Mill 2120
Wastewater Sources
Parameter (1) *
Volume
Ratio
TSS
Cd
cu
Pb
Zn
Hg
Fe
4.2
4
0.33
92.0
<0. 1
172
0.0784
2000
(2)*
1
in
7. 74
36.0
0.1
940
0.0009
2880
(3)*
16.2
282,000
3.0
400
21
310
0.003
18,800
Calculated
Combined After
Levels* Treatment**
(mq/1) (mq/1)
Mean
>282,000 8
2.7
324
16
300
0.015
14,500
0.019
0.04
<0.01
0.10
0.0002
0.14
Range
2-96
.01-0.04
.03-0.25
0.01
0.02-0.96
.0002-0.0003
0.06-1.0
Wastewater Source
1 - Acid Mine Water
2 - Spent Leach solution
3 - Mill Tailing
*Contractor Sampling Data
**Company and Contractor Data Range
486
-------
Table VII-11. REDUCTION OF POLLUTANTS IN CONCENTRATOR TAILS BY SETTLING AT VARIOUS pH LEVELS
PARAMETER
*H
TSS
TIB
Al
C«
c.
r<
Ht
P»
J»
Cv~*.
CONCENTRATION (•**!! 1
RAW
WASTfWATER
(CONTRACTOR
• 1*
m.ooo
_
<002
10
400
U.IOO
0001
11
no
001
MILL 2110
TREATED WASTEWATER
CONTRACTOR
DATA*
«•'
»1
_
sso
OOOI
24
4.1
0 1»
MILL 2122
DATA-'
II1
17
-
-
a 4 mtll tat ««vto
«.«m mUjdlilrni
II «M>. >M*> « h
• ••> f»M 2n m «MC|I«I«^ «
-------
Additional treatment of wastewater by polyelectrolyte
addition, to reduce suspended solids in tailing-pond
discharge, is also practiced at one mill. Secondary
settling ponds are used to settle the treated solids prior
to discharge.
The effectiveness of the use of coagulants (polymers) is
demonstrated in Table VII-12. These data, obtained from a
pilot operation, indicate effective reductions of copper,
iron, and cobalt, with substantial reductions of aluminum
and manganese.
Recycling of process water from the tailing pond has not
been difficult for most copper mills surveyed employing tnis
technique. However, treatment of the pond water has been
necessary for selected problems encountered. Potential
problem areas present at these operations include buildup of
scale deposits, pH changes in the tailing pond or in makeup
water, and presence of flotation reagents in the recycled
water. Effective methods of treatment to alleviate these
conditions are phosphate treatment (softening) for scale
control, adjustment of pH by liming, and the use of aeration
or secondary settling ponds to assist in degradation of
flotation reagents.
Lead and Zinc Ores
A discussion of the treatment and control technologies
currently employed in the lead and zinc ore mining and
dressing industry is included in this section. Two
subcategories are represented: Mines and lead or zinc
mills.
Mines With Alkaline Drainage Not Exhibiting Solubilization
of Metals. The operations generally employ treatment by
impoundment in tailing or sedimentation ponds. Mine 3105
(producing lead/zinc/copper concentrates) is located in
Missouri. The mine recovers galena (PbS), sphalerite
(ZnS), and chalcopyrite (CuFeS). Production began in 1973,
and the operation was expected to produce 997,700 metric
tons (1,100,000 short tons) of ore in 197U.
The water pumped from this mine is treated by sedimentation
in an 11.7-hectare (29-acre) pond. The average mine
drainage flow rate is 8,300 cubic meters (2,190,000 gallons)
per day. The effluent from this basin flows to a nearby
surface stream. The chemical characteristics of the
wastewater before and after treatment are presented in Table
VII-13, together with data for nine months of 1974. The
488
-------
TABLE VI1-12. EFFICIENCY OF COAGULATION TREATMENT TO REDUCE
POLLUTANT LOADS IN COMBINED WASTE (INCLUDING
MILL WASTE) PRIOR TO DISCHARGE (PILOT PLANT - MILL
2122, NOVEMBER 1974)
POLLUTANT
PARAMETER
Flow
PH
TDS
TSS
Al
A*
Cd
Cu
Ft
Pb
BkJ««
win
Hfl
Ni
Co
Zn
WASTE LOAD IN INFLUENT TO PROCESS
kg/1000 metric ton*
76.134 m3/d«v
7.8'
3.500
10
2.3
0.2
<0.05
9.8
120
13
0.4
0.0001
< 0.1
9.8
< 0.05
Ib/IOOOgal
19.850.400 gpd
7.5*
6
0.02
0.004
0.0003
< 0.00009
0.02
0.21
0.006
0.0007
0.000000^
< 0.0002
0.02
< 0.00009
WASTE LOAD IN EFFLUENT TO DISCHARGE
kg/ 1000 metric tons
75.198 m3/d«y
9.0'
3.900
14
< 1
0.9
< 0.05
0.9
0.7
2.8
0.1
0.0003
< 0.1
0.9
<0.05
Ib/IOOOgal
19.886.240 gpd
9.0*
7
0.02
< 0.002
0.002
< 0.00009
0.002
0.001
0.005
0.0002
0.0000005
< 0.0002
0.002
< 0.00009
% EFFICIENCY
IN REMOVAL
_
-
-
-
>S7%
-
-
90%
>99%
15%
71%
-
-
90%
-
•Vdut in pH units
489
-------
TABLE VII-13. CHEMICAL COMPOSITIONS OF RAW AND TREATED MINEWATERS
FROM MINE 3105 (HISTORICAL DATA PRESENTED FOR COMPARISON)
PARAMETER
PH
Alkalinity
Hardness
TSS
TDS
COD
TOC
Oil and Grease
P
Ammonia
Hg
Pb
Zn
Cu
Cd
Cr
Mn
Fe
Sulfate
Chloride
Fluoride
CONCENTRATION (mg/fc)
RAW MINE
DRAINAGE*
7.4* •
196.0
330.4
138
326
<10
< 1.0
29.0
0.030
<0.05
0.0001
0.3
0.03
<0.02
< 0.002
<0.02
<0.02
<0.02
63.5
57
1.2
DISCHARGE*
8.1**
162.0
173.2
< 2
204
<10
3.0
17.0
0.032
<0.05
< 0.0001
0.1
<0.02
< 0.02
0.005
<0.02
0.35
0.11
45.5
44.5
1.0
DISCHARGE (HISTORICAL)"
AVERAGE
7.8**
-
-
3.4
-
-
-
1.9
-
-
-
0.050
0.032
< 0.005
< 0.005
-
-
0.086
-
-
-
RANGE
7.4" to 8.1"
-
-
<1 to 9
—
-
-
< 1 to 5
-
-
-
0.011 to 0.1 2
0.008 to 0.11
< 0.050 to 0.070
(< 0.005)
—
-
0.033 to 0.21
-
-
-
•Analysis of single 4-hour composite sample
f Monthly analysis over January 1974 through September 1974
'•Value in pH units
490
-------
treatment sequence is as follows: mine pumping, followed by
clarification basin, followed by discharge (8,300 cubic
meters (2 190,000 gallons) per day). Relatively simple
treatment employed for mine waters exhibiting chemical
characteristics similar to mine 3105 can result in
attainment of low discharge levels for most constituents.
Reduction of parameters such as total dissolved solids, oil
and grease, chloride, sulfate, lead, and zinc—as well as
excellent reduction of total suspended- solid concentration s-
-is obtained by this treatment method.
Mine Drainage fAcid or Alkaline) Exhibiting Solubilization
oT~MetaT^ - The chSra'cteristics of wastewater from these
mines are such that treatment must be applied to prevent the
discharae of soluble metals, as well as suspended solids.
The treatment practice, as currently employed, involves
chemicat^orten? lime, precipitation and sedimentation.
Mine wastewaters are often treated by discharge into a pond
or basin in which the PH is controlled. An approach often
used is to discharge the mine wastewater into a mill tailing
Dond where wastewater is treated at a pH range which causes
the precipitation of the heavy metals as insoluble
£1 ?5!f The presence of residual solids from the
S2S5 process' if thought to provide nucleation sites for
the precipitation of the hydroxides. In cases where ferrous
J™« il nr-esent, it is desirable to cause the oxidation to
the f«S2 rorm and, thus, to avoid the potential for acid
formation by processes similar to the reactions forming acid
™?^ £*?nlae vigorous aeration of the wastewater can
9 -
usually after addition of the pH-
adjusting agent.
The treatment process described is similar to the type of ^
The treatment: p%ubseauent physical treatment, usually
control, ,and.thSUrro?h!flotation recovery of sulfides of
J^SS^Snc and copper (which is followed by sedimentation
of the tilings)? The milling process itself is, therefore,
rocess of treating mine wastes in this
an analog for a process
subcategory.
an underground mine, located in Maine. The
s sphalerite and the byproducts chalcopyrite,
pyrite which are present in the formation. The
en production 1972 and produced 208,610 metric tons
(230,000 short tons) of ore in 1973.
numoed from the mine, 950 cubic meters (250,000
^day, is treated by mixing it with mill tailing
U91
-------
discharge, plus additional lime as required for pH control,
in a reservoir with a capacity of 37.85 cubic meters (10,000
gallons). The combined waste is then pumped to a 25-hectare
(62-acre) tailing pond. The discharge from the tailing pond
is sent to an auxiliary pond. The combined retention time
in the two ponds is 35 days at maximum flow. Water is
recycled for the process from the auxiliary pond, and the
excess is discharged. The chemical characteristics of the
mine water and the final discharge, treated in the above
manner, are given in Table VII-14,
A pilot treatment plant has been operated at a mill located
in New Brunswick, Canada to develop and demonstrate r.ew ar.d
existing technology for the removal of heavy metals from
base metal mining effluents. Three mine waters,
characterized as strong, weak and moderately strong, have
been evaluated and the results published (Reference 71).
The pilot plant design included provisions for two-stage
lime additions, flocculation, clarification, filtration, and
sludge recycle. The preliminary conclusion (Reference 71)
is that the optimum treatment configuration for the three
mine waters consists of a once-through operation using
polymer and two-stage neutralization (precipitation). Two-
stage neutralization was chosen rather than single-stage,
even though results demonstrated they are equivalent, as the
former is thought to be better able to respond to
neutralization load changes.
The mine water characteristics and attainable metal effluent
concentrations are given in Table Vli-15.
Lead and/or Zinc Mills. As discussed in Section V, the
wastewater from lead/zinc flotation mills differs from mine
water in that a number of reagents are added to effect the
separation of the desired mineral or minerals from the host
rock. These waste streams also contain finely ground rock,
as well as minerals, as a result of grinding to allow
liberation of the desired minerals during the froth-
flotation process.
The most common treatment method in use in the lead/zinc-
milling industry is the tailing or sedimentation pond.
Often considered a simple method of treatment, properly
designed tailing ponds perform a number of important
functions simultaneously. Some of these functions include
removal of tailing solids by sedimentation, formation of
metal precipitates, long-term retention of settled tailings
and precipitates, stabilization of oxidizable constituents.
492
-------
TABLE VII-14. CHEMICAL COMPOSITION OF RAW AND TREATED MINEWATER FROM
MINE 3101
PARAMETER
pH
TSS
Cd
Cu
Pb
Zn
Cr
F«
Mn
CONCENTRATION (mg/ / )
RAW MINE WATER
(CONTRACTOR DATA*)
7.0"*
1047
0.08
£1
1.9
22.9
0.012
22.0
1.7
TREATED DISCHARGE
(COMPANY MONITORING DATA1")
MEAN
8.0"
,v
0.005
0.019
0.024
0.13
0.007
0.30
0.066
RANGE
7.1 to 10.8**
—
< 0.001 to 0.024
0.002 to 0.1 33
0.004 to 0.1 6
0.03 to 0.466
< 0.002 to 0.038
0.026 to 1.498
0.004 to 0.266
* Average of six 24-hour composite samples.
* For period October 1974 through September 1975. Mean values are averages of monthly mean data; range's
lowest monthly average and highest single-day concentrations observed.
••Value in pH units.
tfFrom NPDES Permit Application data.
493
-------
TABLE VII-15. CHEMICAL CHARACTERISTICS OF RAW AND TREATED MINE WATERS FOR
NEW BRUNSWICK, CANADA, COPPER/LEAD/ZINC PILOT-PLANT OPERATION
fAMUAflffl
PH
^. »
t.'
c.'
f,'
COMCf NTKATIOM l~»<|l
MIME 1
RAWIM1NC »O£«
MEAN
-
«*»
18
1UO
flAMGF
».4» «•
ISlilMO
»H 1?
• IS la 32*0
1HEATED DISCHARGE
AD. tan
MfAN
-
DM
BOJ
613
RANGE
-
O l*t«0.1»
gut. OIK
ovtuou
CICAOV tmHATIOM
WtAN
-
OH
«u
5 JO
IIANCf
• MUU>
«.u
A.14MOJC
MIMCI
flAWMINf WfATCR
Mi AN
10*
10
u
HANOI
1» w ] 1*
a t* IT*
1» I»S»
24 I«Z3C
IRi AttO OBCHAKCt
AII run
MEAN
aim
an
• ii
•AMCC
00)1. OS*
«.OI !• • O4
OAiu«n
ST(AOTCr<«ATION
MEAN
• 1*
Ofl]
Oil
XANCE
00]raO-n
e a » o 01
• 11 «»o ii
•mil
«AMM
MCAN
B40
ia
via
ME MAftn
KANCC
lll»I**
•onm
Z4«B M
XOi»13>>
TREATED DISCHARGE
Ml TC*TI
•CAN
OJI
•JM
»«
RAMCE
ODI »
-------
and balancing of influent-water quality and quantity of
flow.
In the lead/zinc-ore milling industry, a biological
treatment method, used in conjunction with stream meanders,
was observed at one location. This treatment method has
been described in the previous discussion in this section.
The ability to recycle the water in lead/zinc flotation
mills is affected by the buildup of complex chemical
compounds (which may hinder extraction metallurgy) and
sulfates (which may cause operating problems associated with
gypsum deposits). One solution to these problems is a
cascade pond system. There, the reclaimed water from
thickeners, filters, and tailing ponds may be matched with
the requirements for each point of the circuit (Reference
72).
In another study (Reference 73), the many operational
problems associated with the recycling of mill water are
described in detail. The researchers have observed that
recycling at the operations studied had not caused any
unsolvable metallurgical problems and, in fact, indicate
that there are some economic benefits to be gained through
decreasing the amounts of flotation reagents required.
Mill 3103 is located in Missouri and recovered galena,
sphalerite, and chalcopyrite from 846,000 metric tons
(934,000 short tons) of ore in 1973.
The mill utilizes both mine water and water recycled from
the tailing pond as feed water. The concentrator discharges
9,500 cubic meters (2,150,000 gallons) per day of tailing
slurry to its treatment facility. The treatment facility
utilizes a 42.5-hectare (105-acre) tailing pond with esti-
mated retention of 72 days, a small stilling pond at the
base of the tailing-pond dam, and a shallow 6.1-hectare (15-
acre) polishing pond before discharge. A schematic diagram
of average daily water flows for the facility is given in
Figure VII-11. Effluent chemical composition and waste load
discharged at mill 3103 using the above treatment are given
in Table VII-16.
Hill 3102 is located in Missouri. This mill processed
approximately 1,450,000 metric tons (1,600,000 short tons)
of ore in 1973. Galena and sphalerite are recovered as
concentrates at this operation.
495
-------
Figure VII-11. SCHEMATIC DIAGRAM OF WATER FLOWS AND TREATMENT
FACILITIES AT MILL 3103
RECYCLE
WATER
3,785 mj/day
< 1,000,000 flpd)
EVAPORATION
AND
SEEPAGE
7.570 m3/day
(2,000.000 gpd)
15,150-m3 (4.000.000-gal)
RESERVOIR
WATER-
TO
SMELTER
•it 1.160 mj/day
(•it 300,000 gpd)
CONCENTRATES
TO
STOCKPILE
9,500 m3/dav
(2,500,000 gpd)
37.9 m3/day
(10,000 gpd)
1,515 mj/day
(400.000 gpd)
( POLI
POLISHING POND
eit 3,785 mj/day
(est 1,000,000 gpd)
10,100 m3/day
(2,600,000 gpd)
DISCHARGE
496
-------
TABLE VII-16. CHEMICAL COMPOSITION AND WASTE LOAD OF TREATED
MILL WASTE WATER AT MILL 3103
PARAMETER
PH
TSS
COD
Oil and grMM
Cyanide
Hg
Pb
Zn
Cu
Cd
Cr
ttj_
irin
Total Fa
CONCENTRATION
-------
The mill utilizes mine water exclusively as feed. It
discharges 15,150 cubic meters (4,000,000 gallons) per day
of tailing slurry to a large tailing pond. This pond also
receives about 3,785 cubic meters (1,000,000 gallons) per
day of excess mine water and another 3,785 cubic meters
(1,000,000 gallons) per day of surface-drainage water. This
tailing pond presently occupies 32.U hectares (80 acres) and
will occupy 162 hectares (UOO acres) when completed to
design. The tailing-pond decant water is discharged to a
small stilling pool and then enters a meander system-, where
biological treatment occurs. An additional sedimentation
basin of approximately 6.1 hectares (15 acres), for removal
by sedimentation of any algae which breaks loose from the
meander system, has been constructed near the end of the
meander system for use just before final discharge. A
schematic diagram of the mill operation and the treatment
facility is presented in Figure VII-12.
Water characteristics for the effluent from the mill, the
overflow from the tailing pond, and the final discharge
treated utilizing the above technology are presented in
Table VII-17.
Mill 3105 is located in Missouri and recovered galena, spha-
lerite, and chalcopyrite from an estimated 997,000 metric
tons (1,100,000 short tons) of ore in 197U.
This mill utilizes water recycled from its tailing-pond
system and makeup water from its mine as feed water. The
mill discharges 7,910 cubic meters (2,090,000 gallons) per
day of wastes to a 11,8-hectare (29-acre) tailing pond. The
decant from this pond is pumped to an 7.3-hectare (18-acre)
reservoir, which also receives the required makeup water
from the mine. The mill draws all its feed water from this
reservoir. No discharge occurs from the mill.
A schematic diagram of the water flows and treatment
facilities is presented in Figure VII-13.
Mill 3101 is located in Maine and recovered sphalerite and
chalcopyrite from 208,000 metric tons (230,00.0 short tons)
of ore in 1973.
This mill utilizes only water recycled from its treatment
facilities as feed water. The mill discharges to a mixing
tank, where mine water is treated by chemical precipitation
that is achieved by combining with the tailing slurry and
liming as required. This combined waste is introduced into
a tailing pond, which discharges to an auxiliary pond. The
498
-------
Figure VII-12. SCHEMATIC DIAGRAM OF WATER FLOW AND TREATMENT
FACILITIES AT MILL 3102 (TAILING POND/STILLING POND/
BIOLOGICAL TREATMENT/POLISHING POND)
TO ATMOSPHERE
22,300 m3/day
(5,900.000 gpd)
7,560 m3/d»y
(2.000,000 gpd I
9.100 mj/d«y
(2.400.000 gpd)
NATURAL
SPRING
34,100 m3/d«y
(9.000,000 gpd)
DISCHARGE
499
-------
TABLE VI1-17. CHEMICAL COMPOSITION AND WASTE LOADING FOR RAW AND
TREATED MILL WASTEWATER FROM MILL 3102
PARAMETER
1*1
TSS
COO
Oil and Graata
Cyaruda
H«
n>
Zn
Cu
Cd
Cf
Mfl
Total F.
TAILING-POND DECANT
CONCENTRATION
Imt/t)'
7.1"
1C
5438
6,0
<0.01
< 0.0001
0.39
0.2*
<0.02
0.00}
<0.02
0.2*
0.16
WASTE LOAD
par unit Of* rmMari
ka/1000 nwirie IBM
_
404
1.MO
174
<0.029
< 0.0003
1
044
teud on 4-houi compomt wmplM
tOi» ««•«• OVM period January tHreufh S*pt«nb*r 1974
"Valua in pH umu
500
-------
Figure VII-13. SCHEMATIC DIAGRAM OF WATER FLOW AND TREATMENT
FACILITIES AT MILL 3105
MINE
10,900 m3/day
(2,880,000 gpd)
2,615 m3/day
(690,000 gpd)
7.3-hactara
(18-acrc)
RESERVOIR
8,300 m3/day
(2.190,000 gpd)
i
MINE-WATER
TREATMENT
8,300 m3/day
(2,190,000 gpd)
DISCHARGE
7,900 m3/day
(2,090,000 gpd)
THICKENERS
MILL
I
TAILINGS
(35% SOLIDS)
Pb
IMMMHI
Ml^^H
Cu
5.510 m3/day
(1,460,000 gpd)
7,900 m3/day
(2,090,000 gpd)
2,380 m3/day
(630.000 gpd)
RECYCLE
5,300 m3/day
(1.400,000 gpd)
501
-------
combined retention time in the two ponds is 35 days at
maximum flow. A schematic diagram of the mill-water circuit
is shown in Figure VII-1U. The separate treatment of mine
water and surface runoff would allow this operation to
achieve total recycle. Discharge data for this mine/mill
complex were presented as mine discharge for mine 3101
earlier in this section.
Mill 3108 is located in Idaho and recovers sphalerite,
galena, and tetrahedrite from approximately 158,725 metric
tons (175,000 short tons) of ore per year.
At this facility, the coarse tailings fraction is mixed -«fir:h
cement and used for backfilling stopes in the mine. Mine
water, including mill wastewater delivered with the sand
backfill, is combined with the mill tailings stream, and
flocculant is added prior to settling in the mill tailing
pond (for approximately 72 hours) and discharge.
Alkalinity, for precipitation of heavy metals, is currently
derived from cement added to mine backfill and from reagent
use in the milling process. Wastewater flow and treatment
practices are illustrated in Figure VII-15, while effluent
characteristics are shown in Table VII-18.
Gold Ores
The discussion that follows describes treatment and control
technology in current use in the gold-ore mining and
dressing industry. Aspects of treatment and control which
are unique to the gold-ore category are described, in
addition.
Mining Operations- Wastewater treatment at mining
operations in the gold-ore mining industry consists of three
options as currently practiced in the U.S.: (1) Direct
discharge without treatment; (2) Incorporation of mine water
into a mill processwater circuit; and (3) Impoundment and
discharge. Impoundment of mine water without discharge may
be currently practiced at locations in arid regions, due to
evaporation.
Wastewater emanating from placer mining operations consists
primarily of water used in a gravity separation process.
Recovery of placer gold by physical methods involves no
crushing, grinding, or chemical-reagent usage. As a result,
the only waste parameters requiring treatment for removal
are the suspended and/or settleable solids generated during
washing (i.e., sluicing, tabbing, etc.) operations, current
best treatment practice in this segment of the industry is
502
-------
Figure VII-14. SCHEMATIC DIAGRAM OF TREATMENT FACILITIES AT MILL 3101
2.15 m3/min (569 gpm)
0.19 m /min
(50 gpm)
0.38 m /min
(100 gpm)
0.03 m /min (8 gpm)
SHIPPED WITH
CONCENTRATE
PROCESS WATER
I
VACUUM PUMP
^
2.01 nrr/min (531 gpm)
0.11 m3/min (30 gpm)
ESTIMATED
MINE WATER
o
0.47 m /min
(125 gpm)
DRILL WATER
0.19 m3/min
(50 gpm)
COOLING WATER
AND UTILITIES
•ER
ES
RUNOFF
FROM RAIN
\
i
NEl
A
NEUTRALIZATION
AS REQUIRED
0.33 to 1.88 m3/min (87 to 497 gpm)
(MONTHLY AVERAGES)
0.99 m3/min (262 gpm)
(YEARLY AVERAGE)
DISCHARGE
503
-------
Figure VII-15. SCHEMATIC DIAGRAM OF WATER FLOW AND TREATMENT FACILITIES
AT MINE/MILL 3108
WATER
SOURCE
(SURFACE STREAM)
PROCESS WATER
2,316 m°/day
(612.000 gal/day)
TSS • 0.1 mg/J
pH « 7.7
CEMENT
PLANT AND
SURFACE
WATER
MILL
• SANDFILL-
273m/day (72.000 gal/day)
273 m/day (72,000 gal/day)
TSS = 28 to 34%
MINE
2.316 mj/day (612,000 gal/day)
TSS = 13 to 27%
pH = 8.0
MINE
DISCHARGE
2,180 mj/day (576.000 gal/day)
TSS= 200 to 400 mg//
pH * 8.4
COMBINED
RAW WASTE
4,496 m°/day
(1.188,000 gal/dayl
TSS - 3 to 10%
CONCENTRATED
FLOCCULANT
(LIQUID
SUPERFLOC 11281
MIXING
TANK
DILUTED (5%)
FLOCCULANT
16.4 mj/day
(4,320 gal/day)
218m'J/dav
(57,600 gal/day)
4,714 mj/day
11,245,600 gal/day I
TSS * 10 mg//
pH = 8.3
DISCHARGE
504
-------
TABLE VII-18. CHEMICAL COMPOSITION OF MILL WASTEWATER FOR MILL 3108
PARAMETER
pH
TSS
Cd
Cu
Hg
Pb
Zn
CONCENTRATION (mg/ I )
RAW WASTEWATER*
7,9**
125,000
1.5
9.0
—
560
182
TREATED WASTEWATERT
MEAN
7.5**
24
0.002
0.01
0.00036
0.242
0.118
RANGE
6.6 TO 9.1**
0.8 T0 134
0.0008 TO 0.004
0.003 TO 0.022
0.00008 TO 0.001 1
0.095 TO 0.48
0.051 TO 0.210
*For 24-hour composite verification sample.
*From company monitoring data for period November 1974 through March 1976. Mean values
are averages of monthly mean data; range is lowest monthly average and highest single-day con-
centrations observed.
**Value in pH units.
505
-------
use of a dredge pond or a sedimentation pond for solids
settling or, in some instances, discharge of wastewater
across old tailings to achieve a filtering effect. The
waste-load reductions achieved by selected placer mining
operations employing this technology are presented in Table
VII-19.
Techniques used for the control of suspended and settleable
solids discharged from placer mining operations, regardless
of size, are not being employed on a major scale at present.
The termination of mining operations, even with treatment
facilities, does not eliminate water-quality degradation,
however, because most operations which use impoundment
usually construct the settling or tailing pond adjacent to
the stream being worked. With erosion taking place
continuously, these facilities are seldom permanent.
Mining operations exploiting lode ores which discharge mine
water from open-pit or underground operations typically
either discharge directly to a receiving stream, provide
process water for a mill circuit, or discharge wastewater to
a mill tailing pond. Examples are underground mines 4102
and 4103 (which discharge directly to streams) and mine 4105
(the discharge of which is used as makeup water in a mill).
Discharge from underground mine 4104 is impounded; however,
seepage from the impoundment pond travels underground to a
nearby stream. At present, no discharge of water from open-
pit mine 4101 is necessary, since no seepage into the pit
occurs. The small amount of precipitation and runoff
entering the pit is simply allowed to evaporate.
Milling Operations. In-plant control techniques and
processes used by the gold milling industry are processes
which were designed essentially for reagent conservation.
These processes are the reagent circuits indicated in the
process diagrams of Figures III-9 and 111-10.
In the cyanidation process used at mills 4101, 4104, and
4105, gold is precipitated from pregnant cyanide-leach
solutions with zinc dust. The precipitate is collected in a
filter press, and the weak, gold-barren cyanide solution
which remains is recycled back to the leaching circuit.
This solution may be used as a final weak leach, or the
solution may be returned to its initial concentration with
the addition of fresh cyanide and used as a strong leach.
In these processes, recycling of cyanide reagent effects an
estimated 33- to 63-percent saving of this reagent. Loss of
cyanide from the mill circuit is primarily through retention
in the mill tailings. Recycling of cyanide reduces the
506
-------
TABLE VII-19. CHARACTERISTICS OF RAW AND TREATED WASTEWATER AT SELECTED PLACER MINING
OPERATIONS
PARAMETER
pH
D.O.
TURBIDITY
(NTU»
TSS
SETTLEABLE
SOLIDS
SIZE OF
OPERATION
IN
AMOUNT OF
MATERIAL
MOVED/DAY
CONCENTRATION
-------
quantity of cyanide used and also reduces the amount of
reagent present in effluent from discharging mills.
In a similar manner, mercury is typically recycled in
amalgamation processes. Currently, amalgamation is
practiced at only one milling operation (mill 4102). This
mill uses a barrel amalgamation process to recover gold. At
this mill, the gold is separated from the amalgam in a high-
pressure press, and the mercury is returned to the
amalgamator for reuse. Some mercury is lost from this
circuit—primarily, through retention in the mill tailings.
Ultimate recovery or removal of mercury from the waste
stream of a mill presents an extremely difficult task. TO
do so requires removing a small concentration of mercury,
usually from a large volume of water. Advanced waste
treatment methods, such as ion exchange, might achieve as
much as 99 percent removal, but the expense for treating
large volumes of water would be high. Primarily as a result
of this, and in light of recent stringent regulation of
mercury in effluents, the gold 01 illing industry has been
taking advantage of the process flexibility available to it
and has, for the most part, replaced amalgamation with
cyanidation processes for gold recovery. This process
flexibility is the best control currently being practiced by
the industry for minimizing or eliminating mercury waste
loading.
The primary wastes emanating from a gold mill are the
slurried ore solids. For this reason, mill effluents are
typically treated in tailing ponds, which are designed
primarily to provide for the settling and collection of the
suspended solids in the mill tailings. In most cases, these
operations discharge from tailing ponds, and the usual
practice is to decant the water from the top of the pond at
a point where maximum clarification has been attained. In
some facilities, two or more ponds are connected in series,
and wastewater is decanted from one to another before final
discharge.
Although the structure, design, and methods of ponding may
vary somewhat in accordance with local topography and volume
of wastewater, the desired goal is the same—to achieve
maximum settling and retention of solids.
To illustrate the effectiveness of settling ponds as
treatment systems in the gold-ore milling industry, the
discussion which follows outlines an operation which
508
-------
recovers gold and other metals and treats wastewater by use
of a tailing pond.
Mill 4102 is located in Colorado. This mill beneficiates
ore containing sulfides of lead, zinc, and copper, in
addition to native gold and silver. During 1973, 163,260
metric tons (180,000 short tons) of ore were milled to
produce lead/copper and zinc concentrates by flotation and
gold by amalgamation.
Makeup water for the mill circuit is drawn from a nearby
creek. This water is introduced into the grinding circuit
for transportation and flotation of the ore. Prior to
entering the flotation circuit, the ground ore is jigged to
produce a gravity concentrate. This concentrate contains
most of the gold, which is recovered by amalgamations After
amalgamation, the jig concentrate is fed into the flotation
circuit, because some lead is contained in the material.
Mill tailings are discharged to a tailing pond at a rate of
2,290 cubic meters (600,000 gallons) per day. Decant from
this pond flows to a smaller polishing pond prior to final
discharge to a stream. The tailing pond and the polishing
pond have a total area of 18.2 hectares (45 acres).
Table VII-20 presents the chemical composition of mill water
and raw and treated waste load for mill 4102, which
practices amalgamation for gold and froth flotation for
sulfide minerals. These data indicate that removal of
selected metals is achieved to a degree; however, the
treatment is most efficient in the removal of suspended
solids.
Mill 4101 is located in Nevada. This mill recovers gold
occurring as native gold in a siltstone host rock which is
mined from an open pit. Schuetteite (HgSO4_.2HgO) also
occurs in the ore body, and mercury is recovered as a
byproduct during furnacing of the gold concentrate. Ore
milled during 1973 totaled 750,089 metric tons (827,000
short tons). This figure normally is 770,950 metric tons
(850,000 short tons) but was lower than usual due to a 20-
day labor strike.
This mill employs complete recycle of the tailing-pond
decant. However, due to consumptive losses, some makeup
water is required, and this water is pumped to the mill from
a well. Water is introduced into the grinding circuit for
transportation and processing cf the ore by the
agitation/cyanidation-leach method.
509
-------
TABLE VII-20. WASTE COMPOSITIONS AND RAW AND TREATED WASTE LOADS
ACHIEVED AT MILL 4102 BY TAILING-POND TREATMENT
PARAMETER
PH
TSS
coo
Oil ind Gr*M«
Cd
C'
C«
Toul ft
Pto
Total Mn
H«
Zr,
MILL WASTEWATER
CONCENTRATION
Img/ >.)
«.!•'
495.000
11 4?
1
<002
CO 02
0.03
1.0
<0.1
B.2S
0.0014
1.3
RAW WASTE LOAD
par unit ort miMad
ko/IOOO malric lone
-
2.B7 1.000
68
5.8
< 0.1?
< 0.12
Ib/IOOOriiorl font
-
5.742.000
132
11.8
< 0.24
C0.24
0.17 ' 0.34
6 12
<06
49
0.008
T.5
< 12
M
0.018
1S.O
TAILING*OND EFFLUENT
CONCENTRATION
lm«/!.1
10.0*
4
22.8S
1
<0.02
O.OS
1.2
1.S
<0.1
6.37
0.0011
0.05
TREATED MASTE LOAD
kg/IOOO metric ton*
-
20
130
6
<0.t
03
7
9
<0.8
40
O.OO6
0.3
Ita/IOOO O\on loni
-
40
280
12
<0.2
0.6
14
H
< 1.2
80
0.012
0.6
*Valu« in pH unilt
'inoultry data monthly
-------
Mill tailings are discharged at a rate of 2,305 cubic meters
(603,840 gallons) per day to a 37-hectare (92-acre) tailing
pond. Approximately 1,227 cubic meters (321,500 gallons)
per day of tailing-pond decant are pumped back to the mill
from a reclaim sump. No discharge from this operation
results. Potential slime problems in the mill circuit are
controlled through adjustment of the pH to 11.7 and by use
of Separan flocculant in the circuit.
Table VII-21 gives the results of chemical analysis of mill
effluent and tailing-pond decant water after treatment. No
waste loadings are given, since no discharge results.
Samples were obtained from this facility to determine the
effectiveness of treatment, even though the mill has no
discharge. Note, however, that this mill has an alkaline-
chlorination unit available for use in cyanide destruction
should emergency conditions require a discharge.
Data from both mills indicate that dissolved heavy metals
are removed to some degree in the tailing pond, but more
effective technology is required for removal of these waste
constituents. Although such technology is not currently
used in the gold mining and dressing industry, it is
currently available and in general use in other segments of
the mining and dressing industry. This technology also has
special application to mine discharges, as they usually
contain relatively high dissolved-metal loads. This
technology will also be applicable to those situations where
sufficient reduction of metals and cyanide in tailing-pond
effluents is not being achieved.
Conventional treatment available for dissolved heavy metals
generally involves:
(1) Coagulation and sedimentation employing alum, iron
salts, polyelectrolytes, and others.
(2) Precipitation with lime, soda ash, or sulfides.
These treatment technologies have been previously discussed
in this section. Treatment by these methods is not normally
practiced in this industry category. However, where metal
mining wastes are treated, the most common means used is to
discharge to a tailing pond, in which an alkaline pH is
maintained by lime or other reagents. Heavy-metal ions are
precipitated at elevated pH; these ions are then settled
out, together with suspended solids, and maintained in
tailing ponds.
511
-------
TABLE VII-21. CHEMICAL COMPOSITIONS OF MILL WASTEWATER AND
TAILING-POND DECANT WATER AT MILL 4101 (NO
RESULTANT DISCHARGE)
PARAMETER
PH
TSS
Turbidity (JTU)
IDS
COD
Oil and Grease
Cyanide
As
Cd
Cr
Cu
Total Fe
Pb
Total Mn
Hg
Zn
CONCENTRATION (mg/ I )
MILL WASTEWATER
12.26*
545,000
6.70
4,536
43
< 1
5.06
0.05
0.10
0.06
0.17
< 0.5
< 0.1
0.02
-
3.1
TAILING-POND DECANT
11.29*
12
1.0
4,194
43
< 1
5.50
0.04
0.02
0.03
0.13
< 0.5
< 0.1
0.90
0.152
2.5
•Value in pH units.
512
-------
Mercury presents a special problem for control, due to its
potential for conversion in the environment to its highly
toxic methyl-mercury form. The amalgamation process still
finds some use in the gold milling industry, and, in
addition, this metal sometimes occurs with gold in nature.
Although mercury will precipitate as the hydroxide, the
sulfide is much more insoluble. It is expected that, where
dissolved mercury occurs in mine or mill wastes, it will be
treated for removal by sulfide addition. This reaction
requires alkaline conditions to prevent the loss of sulfide
ion from solution as H2S. Theoretical considerations of
solubility product and dissociation equilibria suggest that,
at a pH of 8 to 9, mercury ion will be precipitated from
solution to a concentration of less than 10 exp(-41) g/l.
In practice, it is not likely that this level can be
achieved. However, by optimizing conditions for sulfide
precipitation, mercury should be removed to a concentration
of less than 0.1 microgram/liter (0.1 ppb) .
The conditions under which lime precipitation of heavy
metals is achieved must take into consideration auxiliary
factors. As indicated, the most important of these factors
is pH. The minimum solubility of each metal hydroxide
occurs at a specific pH; therefore, optimum precipitation of
particular metals dictates regulation and control of pH.
When more than one metal is to be precipitated, the pH must
necessarily be compromised to obtain the maximum
coprecipitation achievable for the given metals.
Another factor which must be considered is the oxidation
state(s) of the metal or metals to be treated. For example.
As (+5) is much more amenable to chemical treatment than is
As (+3). In addition, cyano-metallic or organo-metallic com-
plexes are generally much more difficult to remove by
chemical treatment than are free metal ions. Where these
factors impede chemical treatment, prior oxidation of the
waste stream can be employed to destroy the metal complexes
and oxidize metal ions to a form more amenable to chemical
treatment. This oxidation may be achieved by aeration of
the waste stream or by the addition cf chlorine or ozone.
To achieve high clarification and removal of solids and
chemically treated metals, it is essential to provide good
sedimentation conditions in the tailing pond. Typically,
this is done in the industry by designing tailing ponds to
provide adequate retention time for the settling of solids
and metal precipitates. Specification of a recommended
retention time for traditional tailing-pond design is
problematical, because the influence of pond geometry,
513
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inlet/outlet details, and other factors that ensure even
distribution and an absence of short-circuiting are of
greater importance than the theoretical retention provided.
A design retention time of 30 days, based on the average
flow to be treated, is often specified and is appropriate if
short-circuiting due to turbulence or stratification does
not occur. The use of a two-cell pond is recommended to
increase control and reliability of the sedimentation
process.
In some cases, suspended solids or metal precipitates may
retain surface charges or colloidal properties and resist
settling. These solids and colloids can be treated for
removal by the addition of coagulating agents, which either
flocculate or act to neutralize or insulate surface charges
and cause the suspended solids and colloids to coagulate and
settle. These agents may be such flocculants as alum
(A12(SO£)3.) or iron salts, or such coagulants as clays,
silica, or polyelectrolytes.
Cyanide destruction has been previously discussed in this
section. The technology for oxidation and destruction of
cyanide is well-known and currently available. where dis-
charges of cyanide have the potential to enter the
environment, complete destruction prior to discharge is
recommended.
Technology For Achieving No Discharge of Pollutants.
Elimination of point discharges is currently being achieved
in the industry by two slightly different technologies:
impoundment and recycle. Where impoundment is used, the
mill tailings are simply discharged to a pond and retained
there. Recycling exists where tailing-pond water is
decanted and returned to the mill for reuse. A mill or
mine/mill complex is potentially capable of employing either
of these technologies, whereas a mine alone may only be able
to make use of impoundment.
The feasibility of impoundment is dependent on the overall
water balance of the location of the mine/mill's mine or
mill. In arid regions, the impoundment of tailings is a
feasible alternative to discharging and is, in fact, being
practiced.
Where recycle systems are employed, the design must also
take water balance into consideration. In those areas where
precipitation exceeds evaporation during all or part of the
year, some system to divert runoff away from the tailing
pond is required to keep excess water in the pond to a
514
-------
minimum. Also, where heavy rainfalls periodically occur,
tailing ponds must be designed to hold the excess water
accumulated during these periods. A mine/mill complex may
find it necessary to segregate the mine and mill effluents
to further relieve the recycle system of excess water. In
such cases, it is expected that the mine effluents will be
treated by the chemical methods discussed previously and
then discharged.
To some extent, a mill may depend on inherent loss of water
from the system to maintain a balanced recycle system.
These losses include any or all of the following:
(1) Consumptive losses in the milling process (i.e.,
retention of mositure in the concentrate, etc.);
(2) Retention of moisture by the tailing solids in the
tailing pond;
(3) Evaporation;
(
-------
The feasibility of a recycle system must also consider the
effects of the reclaim water upon the mill circuit. For
example, it has been indicated previously that reclaiming
cyanidationprocess water could result in a loss of gold
should this water be introduced at the ore-grinding stage.
In the Province of Ontario, it has been found that the level
of cyanide in the tailing-pond decant from active mine/mill
operations approximates 0.02 to 0.5 percent of total cyanide
mill additions (Reference 64). However, data indicate that
the concentration of cyanide in tailing-pond decant may
build up if the decant is being reclaimed. If this occurs,
the alkaline-chlorination method can be used for cyanide
destruction. Complete destruction of cyanide can be
achieved by excess addition (8.5:1) of chlorine. On this
basis, the recycling of cyanidation-process water is
considered technologically feasible.
Recycling and zero discharge are currently being
accomplished at mill 4101, which is milling gold by the
cyanide/agitationleach process (Figure 111-10) . The overall
water balance for this mill has been presented in Figure V-
22. Treatment efficiency data for this mill, presented in
Table VII-21, indicate a buildup of dissolved solids and
cyanide in the reclaim water. However, no loss in percent
recovery as a result of recycling has been reported by this
mill. In addition, the recovery rate for this mill does not
differ from that of cyanidation mill 4105, which does not
recycle process water.
silver Ores
The discussion which follows describes treatment and control
technology currently employed in the silver-ore mining and
dressing industry. Aspects of treatment and control
pertaining to the silver-ore category are described.
Mining Operations* Wastewater treatment at silver mining
operations primarily consists of discharge of wastewater to
a mill tailing pond, or direct discharge without treatment.
Mining of silver ores primarily exploits the sulfide
minerals tetrahedrite ((Cu, Fe, Zn, Ag) "12.Sbf»S13) and
argentite (Ag2S) and native silver. Native silver often
occurs with gold, copper, lead, and zinc minerals. Little
water use is encountered in silver-ore mining, with the
exception of dredging, where silver is recovered as a minor
byproduct.
516
-------
separate treatment of mine water per ^se is not typically
practiced in this industry; however, where practiced
treatment is performed in conjunction with treatment of mill
wastewater in a tailing pond.
Milling Operations. As discussed in Section V, milling
processes currently employed in the silver industry are
froth flotation (about 99 percent of U.S. mill production)
cyanidation of gold ores, and amalgamation. Cyanidation and
amalgamation recovery of silver currently constitute
approximately 1 percent of U.S. silver production by
milling. The occurrence of silver, either with gold in a
free state or as a natural alloy with gold, has also
resulted in production of silver at refineries. Silver is
often recovered also as a byproduct of the smelting and
refining of copper, lead, and zinc concentrates.
Cyanidation for gold and silver is currently being practiced
at mill 4105 (gold category), but wastewater treatment tech-
nology as currently practiced consists of a sand reclaimer
pond for removal of coarse solids only. Amalgamation for
gold and silver is currently limited to one known site.
Wastewater treatment at this facility has been described
previously for mill 4102.
Mill 4105, which recovers both gold and silver, currently
practices in-plant recycling of reagents, as indicated in
Section III for Gold Ores. This results in economies of
both cost and reagent use, as well as prevention of the dis-
charge of cyanide for treatment or into the environment.
In-plant control practices common to silver flotation mills
are based on good housekeeping measures, employed to prevent
spills of flotation reagents. The feed of these reagents,
into a circuit is carefully controlled, because a sudden
increase or decrease of some reagents could have adverse
effects on recovery from the flotation circuit.
Wastes resulting from silver milling are typically treated
in tailing ponds. These ponds function primarily to
facilitate the settling and retention of solids. Except in
the case of total impoundment, the clarified tailing-pond
water is currently discharged. At mill 4401, a further
reduction of waste loading is achieved by partial recycle of
the tailing-pond decant water (approximately 60- to 75-
percent recycle). Mill 4402 has achieved zero discharge
through total recycle of tailingpond decant water.
Flotation is the predominant method currently used to
concentrate silver ore. Flotation circuits are commonly run
under alkaline conditions. For example, soda ash, caustic
517
-------
soda, and hydrated lime are added to the circuit of mill
4402, and lime is added to the circuit of mill 4401. These
reagents are added to the mill circuits to act as
depressants and pH modifers and consequently make the
tailing pond alkaline. This facilitates the removal of
metals as hydroxides in the tailing pond. However, note
that the reagents producing an alkaline pH in the tailing
pond are added in the mill to control the process conditions
there, and a high degree of control over the pH in the
tailing pond is not currently practiced in the industry. To
facilitate optimum precipitation of metal hydroxides in the
tailing pond, a higher degree of control over the pH may be
required in some cases. Highly alkaline conditions (pH
range of 10 to 11) may be required to effect greater removal
efficiency in treatment facilities.
The presence of antimony in wasteviater has been noted,
because it is closely associated with silver in some ore
bodies—especially, those of the Coeur d'Alene District of
Idaho. The hydroxide of antimony is not reported to exist
but the sulfide of antimony is relatively insoluble;
therefore, treatment for antimony removal will involve
sulfide precipitation. Although Na^S is itself toxic at
high concentrations, the amount required to treat the levels
of antimony found in mine and mill wastewater (approximately
2 to 3 mg/1) is small (approximately 1 mg/1) and will be
consumed in the precipitation reaction. Sulfide
precipitation must be carried out under alkaline conditions
to prevent the removal of sulfide ion from solution as H.2S
gas.
Cyanide is used as a pyrite depressant at mill 4401. This
mill is also recycling its process water with no apparent
adverse affects from this reagent. However, should the
destruction of cyanide become necessary for process control
or as a safety measure in treating accidental leaks from the
treatment system, alkaline-chlorination, ozonation, or
hydrogen peroxide treatment are effective treatment
technologies for the destruction of cyanide. These
processes have been discussed previously in this section.
An example of tailing-pond treatment as practiced at mill
4401 is described below.
Mill 4401 is located in Idaho. Ore is brought to the mill
from an underground mine. Valuable minerals in the ore body
are primarily tetrahedrite, but chalcopyrite- and galena also
occur. During 1973, 182,226 metric tons (200,911 short
tons) were milled to produce a copper/ silver concentrate.
518
-------
Water used at the mill consists of both reclaim water and
makeup water, pumped from a nearby creek. This water is
introduced into the grinding circuit for the transportation
and flotation of the ground ore. Mill tailings are
discharged at a rate of 3,188 cubic meters (835,200 gallons)
per day to the tailing-pond system. This system is composed
of three tailing ponds and a clarification pond. Two of the
tailing ponds are inoperative, due to extensive damage
resulting from a recent flood. Prior to this flood,
tailings were distributed to the three ponds, and their
decant was pumped to the clarification pond. This system
covers a total area of 4.5 hectares (10.9 acres).
Presently, water is both discharged and recycled back to the
mill from the clarification pond. Approximately 1,649 cubic
meters (432,000 gallons) per day are recycled, while 1,141
cubic meters (299,000 gallons) per day are discharged. Mine
water is also discharged to this pond system at a rate of
553 cubic meters (145,000 gallons) per day.
A new tailing pond is under construction and is expected to
be in use soon. This pond will have an area of 6.9 hectares
(17.0 acres).
Table VTI-22 gives the chemical composition of raw and
treated waste loads from mill 4401, which uses tailing pond
treatment. Decreases in several parameters, in addition to
suspended-solid removal, are noted. TOC, COD, cyanide,
copper, mercury, and nickel are all reduced significantly.
Control and Treatment Technology To Achieve No Discharge.
Currently, two silver mills are recycling their process
water. Mill 4402 reclaims all of its tailing-pond decant,
while mill 4401 presently reclaims approximately 60 percent
of its tailing-pond decant. However, operation of mill 4401
with complete recycle could be achieved, and would be, were
it not currently less expensive to use fresh water pumped
from a nearby well, rather than recycled process water from
an impoundment as makeup water.
The feasibility of recycle entails consideration of the
overall water balance at a given mill and possible
interferences in the mill circuit caused by the recycling of
process reagents and/or buildup of dissolved solids. Water-
balance considerations and recycling of cyanide reagent have
been discussed previously in Section VII.
Silver ores are concentrated primarily by the froth
flotation process, and it has been noted previously that
recycled flotation reagents might interfere with the mill
519
-------
TABLE VII-22. WASTE COMPOSITIONS AND RAW AND TREATED WASTE LOADS
AT MILL 4401 (USING TAILING-POND TREATMENT AND
PARTIAL RECYCLE)
f*AM*t~t*
PM
TSS
Turbidity IJTU)
COO
TOC
Oil and CtwM
Cv.mdi
At
Cd
C.
Cu
Tolll Ft
P*
Mn
H«
Ml
*t
Zn
Sb
I MILL WASTEWATER
CONCENTRATION
Imi/il
-
sss.ooo
2.0
S»4
22.0
7
o.os
<0.07
<0.02
<0.1
0.2S
-
<0.1
-
0.0014
0.14
<0.02
C0.02
US
MAW WASTE LOAD
pt« unit Of* milled
h^lOOO itMtric
-------
circuit. However, no published data exist which would
support this position. Recycling successfully being carried
on at mill <*U02 (total recycle—no discharge) and mill 4U01
(partial recycle) demonstrates the feasibility of achieving
total recycle and zero discharge. It is expected that
unwanted quantities of a particular frother appearing in a
recycle stream (from a tailing area, etc.) can probably be
reduced or eliminated by:
(1) increasing the retention time of the frother-con-
taining wastes to facilitate increased oxidation or
biodegradation before recycle to the mill; or
(2) oxidation of the frothers through application of a
degree of mechanical aeration, etc., to the waste
stream; or
(3) selecting another frother with superior breakdown
properties for use in the mill.
A further degree of control of the recycle system can be
gained by use of a two-cell pond. In this system, clarified
water from the primary pond would be decanted to the second
pond, which would be used as a surge basin for the reclaim
water. This system would lend itself to increased control
over the slime content of reclaim water. This is desirable,
since these slimes have been thought to inhibit
differentialflotation processes in some mills. In addition,
the second pond would provide a site for the. implementation
of mechanical aeration, should this treatment become
necessary.
Segregation of Waste Streams . At certain mine/mill
complexes, for the mill to achieve a balanced recycle
system, it may be necessary to segregate the mine and mill
waste streams. In such cases, it is expected that, prior to
discharge, the mine effluents would be chemically treated
for the removal of metals and suspended solids in settling
ponds. As previously discussed, this treatment would
normally involve precipitation of metals using lime and/or
sulfides.
The discussion which follows describes a silver milling
operation currently operating with recycle and zero
discharge.
Mill HHQ2 is located in Colorado. Ore is brought to the
mill from an underground mine. Valuable minerals in the ore
body include sulfide of silver—primarily, argentite,
521
-------
galena, and free or native silver. During 1973, 75,005
metric tons (82,696 short tons) of this ore were milled to
produce a lead/silver concentrate.
Process water is recycled at this mill. However, makeup
water is required, and this water is pumped from a well.
Water is introduced into the grinding circuit to facilitate
transportation and flotation of the %ground ore. Mill
tailings are sent through two stages of cyclones to remove
sands, which are used for backfilling stopes in the mine.
Cyclone overflow is discharged to a 1.6-hectare (U-acre)
tailing pond at a rate of 1,511 cubic meters (396,000
callcr.s) per day. Clarified pond water is recycled bacfc --t,
the mill at a rate of 962 cubic meters (252,000 gallons) per
day.
A new tailing pond is being built at this mill. This pond
will have an area of 6 hectares (15 acres).
Table VII-23 demonstrates the treatment efficiency achieved
in the mill tailing pond and compares mill raw-wastewater
input to tailing-pond decant water recycled to the mill. No
waste loads are presented, because no discharge results.
Bauxite Ore
As discussed in Section IV, Industry Categorization, two
bauxite mines currently operating in the U.S. extract
bauxite ores from open-pit and underground mines. The
characteristics of pollutants encountered in wastewaters
from these operations are discussed in Section V. The
current treatment technology and industry practice for
treatment of bauxite-mine drainage are described below.
Lime neutralization is the only treatment method presently
being employed by the two domestic bauxite producers to
treat mine water. Both acidic and alkaline waters are
treated by this technique, but, due to the relatively small
amount of alkaline water that is treated daily (83 cubic
meters, or 22,000 gallons, per day), only acid mine-water
neutralization is discussed in detail here.
Generally, mine water and surface drainage destined for
treatment undergo settling in a number of natural
depressions, sumps, and settling ponds before reaching the
lime-neutralization facility; thus, suspended-solids
loadings are reduced.
522
-------
TABLE VII-23. CHEMICAL COMPOSITIONS OF MILL RAW WASTEWATER
AND TAILING-POND DECANT WATER AT MILL 4402
PARAMETER
TSS
Turbidity (JTU)
COD
TOC
Oil and Grease
Cyanide
As
Cd
Cr
Cu
Total Fe
Pb
Total Mn
Hg
Ni
Ag
Zn
Sb
CONCENTRATION (mg/ 1 )
MILL RAW WASTEWATER
90,000
1.05
22.70
29.0
2
< 0.01
0.07
< 0.02
< 0.1
0.22
1.80
0.56
1.75
0.149
0.10
< 0.02
0.37
< 0.2
TAILING-POND DECANT
2
0.575
22.70
17.5
2
< 0.01
< 0.07
< 0.02
< 0.1
< 0.02
1.59
0.10
1.80
0.002
0.11
< 0.02
2.3
< 0.2
523
-------
The addition of lime to raw mine drainage to reach elevated
pH causes precipitation of heavy metals as insoluble or
slightly soluble hydroxides. Formation of specific metal
hydroxides is controlled by pH, and removal of the suspended
hydroxides is accomplished by settling. The discussion of
this treatment technique is presented in the early portion
of Section VII under Chemical Precipitation.
Two variations of lime storage at bauxite-minewater-
treatment facilities are employed, and both systems achieve
slightly different efficiencies of pollutant removal. The
pH and pH control of the limed solution are the dominant
factors in determining concentration levels attained ir.
settling ponds.
Figure Vll-16 is a schematic flowsheet of the lime-
neutralization facility at open-pit mine 5102. Both mine
drainage treatment systems investigated during this study
are of this type and are discussed by plant code below.
Mine 5101. Open-pit mine complex 5101 is located in
Arkansas and produces about 2,594 metric tons (2,860 short
tons) of high-silica bauxite daily. There are several pits
associated with the water-treatment facility, and acid
waters collected from the pits, spoils-storage areas, and
disturbed areas are directed to the treatment plant.
Mine 5101 treats the major portion of its open-pit mine
drainage through a treatment plant similar to that shown in
Figure VII-16. Other open-pit drainages which require
intermittent pumping for discharge will be treated by a
mobile lime-treatment plant in the near future. At Mine
5101, about O.U5 kg (approximately 1 pound) of slurried lime
is used to neutralize 3.79 cubic meters (1000 gallons) of
acid mine water. This facility has a controlling pH probe,
located in the overflow from the detention tank, which
activates the automatic plant and pump cutoffs at a high
point of pH 9.0 and a low point of pH 6.0- The operating pH
generally ranges from 7.5 to 8.0, and the pH of the effluent
discharge ranges from 6.3 to 7.3.
Table VII-2U lists analytical data for raw mine water (silt-
pond overflow) and treated effluent (as the discharge leaves
the overflow weir at the sludge pond).
Mine 5102. open-pit mine 5102 is also located in Arkansas
and mines a high-silica-content bauxite deposit.
Contaminated surface drainage from outlying areas and
groundwater accumulation in the holding pond produce about
524
-------
Figure VI1-16. LIME-NEUTRALIZATION PLANT FOR OPEN-PIT MINE 5102
LIME-SLURRY
STORAGE
TANKS
MIXMETER
PH
SENSOR
RAW-WATER
HOLDING
POND
1.84 m^/min
(486 gpm)
SLUDGE
SETTLING
POND
CLEAR-WATER
SETTLING
POND
525
-------
TABLE VII-24. CHEMICAL COMPOSITION OF RAW AND
TREATED MINE WATERS AT MINE 5101
PARAMETER
PH
Acidity
Alkalinity
Conductivity
YDS
TSS
Total Fe
Total Mn
Al
Ni
Zn
Fluoride
Sulfate
CONCENTRATION (mg/2)
RAW MINE DRAINAGE
RANGE
2.8 to 4.6t
-------
1U,1«0 cubic meters (4,000,000 gallons) of raw drainage
daily. Surface drainage collects from an area of
approximately 662 hectares (1,635 acres) of disturbed and
undisturbed land.
An experimental lime-neutralization plant has been operated
at mine 5102 and processes approximately 2,650 cubic meters
(700,000 gallons) per day of acid mine drainage.
This mining operation presently treats less than 10 percent
of its total raw mine drainage, but full-scale operation of
a treatment plant having a capacity of 11,355 cubic meters
(3,000,000 gallons) per day is expected in mid-1975. The
new plant will operate similarly tc the present plant, but
an enlarged system of settling lagoons and sludge drying
beds should provide adequate treatment efficiency.
The treatment used at mine 5102 involves slurried storage of
lime in large agitator tanks for eventual mixing with mine
water in the confines of a pipeline. About 0.83 kg (1.82
Ib) of hydrated lime is used to neutralize 3.79 cubic meters
(1000 gallons) of raw mine water. This lime rate maintains
the influent to the sludge pond at a pH of 9.0 to 11.0, and
effluent from the clear-water settling pond varies from a pH
of 6.0 to 8.0.
Table VII-25 lists the chemical composition of both raw mine
vater (influent to the treatment plant) and the treated
effluent (discharge from clear-water settling pond).
Ferroalloy Ores
The ferroalloy-ore mining and dressing category includes,
for purposes of treatment here, operations mining and bene-
ficiating ores of cobalt, chromium, columbium and tantalum,
manganese, molybdenum, nickel, tungsten, and vanadium (one
operation extracting non-radioactive vanadium). Vanadium
obtained from milling of uranium, vanadium, and radium ores
under NRC licensing is covered as part of the uranium-ore
category. Since the subcategorization of this category is
not based upon end product recovered, but rather upon the
process used, representative mines and mills are used to
illustrate wastewater treatment and control as practiced in
ferroallcy-ore sufccategories.
Currently, there are no operations mining or beneficiating
ores of chromium, cobalt, columbium , and tantalum. A
manganiferous ore is currently being mined at one location
in the U.S., but no wastewater results, and no milling
527
-------
TABLE VI1-25. CHEMICAL COMPOSITIONS OF RAW AND
TREATED MINE WATERS AT MINE 5102
PARAMETER
PH»
Acidity*
Alkalinity
Conductivity *
TDS
TSS*
Total Fe»
Total Mn
Al*
Ni
Zn
Sr
Fluoride
Sulfate*
CONCENTRATION
-------
activities are carried on. A second manganiferous ore mine
and mill was expected to reopen in late 1975 or 1976.
Consequently, treatment and control technology currently
employed in the molybdenum, nickel, tungsten, and vanadium
industries will be used as examples here to represent
treatment used in subcategories of this category.
Mining Operations. Mining of ferroalloy ores is by both
underground and open-pit methods. Mine wastewater is
characterized by high and variable flow and dissolved heavy
metals, and is often acidic. At open-pit mines, seasonal
fluctuations in mine water may be extreme. At such opera-
tions, acidic streams from sulfides in mine waste dumps add
to the waste 'load of the wastewater requiring treatment.
Mine water is often used as mill process water at
underground mines. At open-pit operations, seasonal
variability generally makes mine water an unacceptable
source of process water. Treatment for suspended-solid
removal is almost universally practiced in the ferroalloy-
ore mining industry. Both treatment in tailing ponds with
mill wastewater and use of separate treatment systems such
as settling ponds and clariflocculators (variants of
mechanical clarifiers in which mixing is provided for
flocculant distribution) are used. Where waste streams are
acidic, neutralization is generally practiced. Where open-
pit mining and ore stockpiling are practiced, the potential
for oxidation of metals (especially, molybdenum) increases,
yielding higher levels of concentration of dissolved heavy
metals and, thus, increased raw waste loads.
Examples of treatment practice are given in discussions that
follow, using mines 6103, 6104, and 6107 as examples. In
addition to these sites, mine water at mine 6102 is treated
by neutralization and by a closed-circuit mill tailing pond
from which only seasonal discharge results. Runoff from
mine 6106 is treated by settling only.
Mine 6103. This mine is an underground molybdenum mine, in
CoToradoT which is still under development. Treatment of
mine water at this site during development of the mine has
included flocculant addition, spray cooling, and solids
removal in a series of three settling ponds. Sanitary
wa«<-ewater from the mine site is given tertiary treatment in
a separate facility prior to mixing with mine water in the
first settling basin. Samples of the 9,265 cubic-meter/day
(2.5 mgd) mine-water flow were obtained at the point of
discharge from the mine and at the overflow from the third
settling pond. The results of chemical analyses of these
529
-------
samples of raw mine water and effluent from the treatment
system are presented in Table VII-26.
Appreciable reductions of suspended solids and the heavy
metals Cu, Mn, Pb, Zn, and Fe are evident. The influence of
highly treated sanitary waste is, apparently, reflected in
elevated COD values at the effluent from the treatment
system.
Mine 6104 . This mine is an underground mine, located in
California, which obtains a complex ore yielding tungsten,
molybdenum, and copper. The mine produces approximately
2,200 metric tons (2,425 short tons) of ore per day. Mine
water pumped from the mine daily totals 47,000 cubic meters
(13,000,000 gallons), of which approximately 7,000 cubic
meters (1,848,000 gallons) are used, untreated, as mill
process water. The remainder is treated for solids removal
in a clariflocculator. Underflow from the clariflocculator
is pumped to the mill tailing pond for further treatment.
The bulk (approximately 90 percent) of clarified overflow is
discharged, with the balance used as mill process water.
Table VII-27 presents the results of chemical analyses of
raw mine water and the effluent from the clariflocculator.
A clariflocculator is used for treatment because of severely
limited land and space availability in this area of very
high relief (steep terrain). The use of ammonium nitrate-
based blasting agents previously contributed to elevated
nitrate and nitrogen levels in mine wastewater. This
situation has been largely alleviated by a change in
explosives used at the mine.
In addition to a significant reduction of suspended-solid
concentrations, important reductions of Pb, Mn, and Fe have
been noted.
Mine 6107. This mine is an open-pit vanadium mine, working
non-radioactive ore. This operation is located in Arkansas,
an area of high annual rainfall. The mine area is drained
by two streams, which are considered as mine wastewater and
are treated via neutralization by ammonia. Part of the
wastewater is also treated by settling behind a series of
rock dams.
Table VII-28 presents the results of chemical analyses of
raw and treated mine wastewater at mine 6107.
Neutralization and settling treatment is employed at mine
discharge 005, and neutralization treatment alone is used at
discharge 004. The presence of ammonia in the effluents
reflects the use of ammonia for neutralization. Residual
530
-------
TABLE VII-26. CHEMICAL COMPOSITIONS OF RAW MINE WASTEWATER
AND TREATED EFFLUENT AT MINE 6103
PARAMETER
TSS
TDS
Oil and Grease
COD
As
Cd
Cu
Total Mn
Mo
Pb
V
Zn
Total Fe
Fluoride
CONCENTRATION (mg/£)
BEFORE TREATMENT
802.9
726
1.0
<10
<0.01
0.16
0.06
5.5
<0.1
0.19
<0.5
0.47
17.0
4.5
AFTER TREATMENT
24.3
564
1.0
67.5
<0.01
<0.01
<0.02
1.0
<0.1
0.03
<0.5
<0.02
0.17
3.7
531
-------
TABLE VII-27. CHEMICAL COMPOSITIONS OF RAW AND TREATED
MINE WATERS AT MINE 6104 (CLARIFLOCCULATOR
TREATMENT)
PARAMETER
PH
TSS
Oil and Grease
COO
As
Cd
Cu
Mn
Mo
Pb
V
Zn
Fe
Fluoride
CONCENTRATION (nig/d)
RAW WASTEWATER
6.5*
33.9
2
91.3
<0.07
<0.01
<0.02
0.21
<0.1
0.14
<0.5
0.05
1.51
0.52
TREATED WASTEWATER
7.8*
3.1
2.7
91.3
<0.07
<0.01
<0.02
0.03
<0.1
0.02
<0.5
0.03
0.12
0.46
Value in pH units
532
-------
TABLE VI1-28. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AT MINE 6107
PARAMETER
Flow
TSS
TDS
Oil and Grease
COD
Ammonia
Ai
Cd
Cu
Mn
Mo
Pb
Zn
Fe
Fluoride
CONCENTRATION Ug/H)
DISCHARGE 005
RAW MINE WATER
15.000 m3/day
(4.300,000 gpd)
-
366
-
31
—
<0.07
< 0.005
<0.02
6.8
—
—
0.09
-
-
TREATED EFFLUENT .
(NEUTRALIZATION & SETTLING) T
15,000 m3/day
(4.300,000 gpd)
30
285
<1
5
5
0.020
0.0^
0.010
45
< 0.100
< 0.010
0.25
3.6
<1
DISCHARGE 004*
TREATED EFFLUENT
(NEUTRALIZATION ONLY) T
5,000 m3/day
(1,400,000 gpd)
15
105
<1
5
10
0.01
<0.01
<0.01
0.94
<0.10
<0.01
0.18
<0.10
<1
*Analysit of raw mint water unavailable for Difcharge 004
Company data
533
-------
levels of iron and manganese in effluent from discharge 005
are noteworthy.
Milling Operations. The ferroalloy-ore milling industry has
been subcategorized on the basis of process used and size,
as described in Section IV. No exemplary operations were
visited which belong to the mill subcategory representing
operations processing less than 5,000 metric tons (5,500
short tons) per year. Operations representative of the
remaining milling subcategories provide examples of the
processes and all treatment options applicable to small
operations as well. Treatment technology currently
practiced is relatively uniform throughout the ferroalloy
milling industry, although some examples of treatment for
waste constituents peculiar to particular subcategories have
been observed.
Commonly practiced treatment includes settling,
neutralization, and recycle of process water. In addition,
sites visited were observed to practice lime precipitation,
distillation, and air stripping.
Mill 6101. This operation is a flotation mill recovering
molybdenite concentrate on a large scale (approximately
14,000 metric tons, or 15,400 short tons, ore milled, per
day). Mill 6101 is located in a mountainous area of New
Mexico. Approximately 22,000 cubic meters (6,000,000
gallons) of water are used in froth-flotation processing
each day. No mine water is produced, with process water
being drawn from wells and a nearby river. Ore processing
consists of crushing, grinding, and froth flotation. (See
Section V.)
Treatment at mill 6101 utilizes tailing ponds and an
additional settling pond for removal of residual suspended
solids. Flocculants are added to the tailing stream, if
required for settling prior to discharge. Limited amounts
of water are reclaimed in thickeners at the mill site.
Because the mill circuit is mildly alkaline, lime is not
required to maintain neutral pH in the effluent stream.
Because the terrain near the mine and mill site did not
allow development of a sound tailing-disposal area, water-
treatment facilities are located at a significant distance
(16 km, or 10 miles) from the mill. Tailings are delivered
to the tailing ponds as a slurry, pamped through three 16-
kilometer long (10-mile-long) steel pipelines, two of which
are 25 cm (10 in.) in diameter, and one of which is 30.5 cm
(12 in.) in diameter. Because of abrasive wear on the
534
-------
pipe, it is necessary to rotate and replace piping
frequently. The use of end-of-line monitors in the mill
control room, a change to more abrasion resistant neoprene-
lined pipe, and a large tailing-disposal maintenance staff
have essentially eliminated problems with recurrent spills
of tailings from pipe breaks, which were experienced in the
past.
Three impoundments are used at mill 6101: two tailing ponds
totaling approximately 121 hectares (300 acres) in area, and
a secondary settling pond with a 1.6-hectare (4-acre)
surface area. The older of the two tailing ponds is nearly
full and partly revegetated. The second pond contains a
water pool of approximately 160 hectares (40 acres).
Seepage through the second dam is limited by use of an
asphalt liner. Discharge from the secondary settling pond
flows through a small surface channel to the final discharge
point.
In addition to the tailing and settling ponds, construction
at the tailing-disposal site includes a diversion ditch and
a flood-control dam to regulate drainage from a mountain,
northeast of the tailing ponds. These diversion structures
are sealed to protect the tailings area from the 100-year-
frequency storm. Water recycle from the tailing basin is
rendered extremely difficult at this plant by the large
separation between the mill and tailing area, although it is
technically compatible with the recovery practice.
Table VII-29 is a compilation of company chemical data for
intake and treated discharge waters. Table Vll-30 presents
data for effluent treated using a tailing pond with
secondary settling. Raw-waste characteristics for mill 6101
were presented in Section V. The effectiveness of this
treatment scheme for suspended-solid removal is evident.
The alkalinity of the mill wastewater results in the
effective removal of most heavy metals in the tailing basins
and settling pond, significant reductions of Cd, Cu, Fe,
Mn, Pb, and Zn were noted in this treatment scheme. Only
total dissolved solids are discharged at a level in excess
of 0.1 kg/metric ton (0.2 Ib/short ten) of ore milled.
Mill 6102 . At this mill, molybdenite concentrates are
recovered by flotation. Byproduct concentrates of tin,
tungsten, monazite, and pyrite are recovered in a complex
system involving gravity separation, froth flotation, and
magnetic separation. Monazite and pyrite concentrates are
currently delivered to the tailing impoundment for disposal;
they are not shipped. Ore processed is 39,000 metric tons
535
-------
TABLE VII-29. ANALYSES OF INTAKE AND DISCHARGE WATERS FROM
MILL 6101 (COMPANY DATA)
PARAMETER
Alkalinity
BOO (5-day)
COD
TDS
TSS
Hardness
Ammonia (As N)
Nitrate
Phosphorus
Al
So
As
Ba
Be
B
Cd
Ca
Cn
Co
Cu
AVERAGE
CONCENTRATION
fmg/J?)
INTAKE
40
<30
<50
260
55
155
0.6
0.1
<0.01
0.24
<0.1
—
< 0.001
< 0.002
<0.1
< 0.002
103
< 0.01
< 0.005
0.02
DISCHARGE
30
<30
<50
600
100
800
1.0
0.1
0.04
0.2
< 0.1
—
< 0.001
< 0.002
< 0.1
< 0.002
277
< 0.01
< 0.005
0.02
PARAMETER
Fe
Pb
Mg
Mn
Ag
Mo
Ni
K
Se
Ag
Na
Sn
Ti
Zn
Sulfate
Chloride
Fluoride
Cyanida
Thiocyanate
AVERAGE
CONCENTRATION
(ma/fc)
INTAKE
0.4
< 0.005
10
0.9
< 0.0001
0.01
0.02
1
< 0.005
< 0.001
3
< 0.01
< 0.08
0.05
100
2
0.2
—
•••
DISCHARGE
0.16
< 0.005
30
0.9
< 0.0001
2
0.017
31
< 0.005
< 0.001
50
<0.01
<0.08
<0.06
1000
2
1.5
—
0.6
536
-------
TABLE VI1-30. CHEMICAL COMPOSITION OF WASTE WATER AND WASTE LOADING
FOR MILL 6101
PARAMETER
TSS
TDS
Oil Mid GrMM
COO
Total CycnkU
As
Cd
Cu
ftj_
Will
Mo
Pb
Zn
F«
Fluorid*
CONCENTRATION
(mil 9 )
4.3
2,272
3
19.8
0.03
0.02
<0.01
<0.02
1.3
4.0
0.13
0.02
0.10
X4
TOTAL WASTE
k9/d«y
73
30.000
51
340
0.51
0.34
< 0.2
< 0.3
22
68
2.2
0.34
1.7
58
Ib/diy
160
86.000
112
750
1.1
0.75
<0.4
<0.7
48
150
4.8
0.75
3.7
130
WASTE LOAD
ptr unit or* miltad
kg/1000 metric tons
5.2
2400
3.6
24
0.036
0.024
<0.01
< 0.02
1.6
4.9
0.16
0.024
0.12
4.1
lb/1000 short tons
10
5,600
7.2
48
0.072
0.048
<0.03
< 0.04
3.2
9.8
0.32
0.048
0.24
8.2
537
-------
(43,000 short tons) per day. This mill is located in
Colorado in a mountainous area.
This operation uses water on a complete-recycle basis for
ten months of the year. During this period, due to consump-
tive losses in the mill, seepage losses, and evaporation
from tailing and water-storage ponds, the net water balance
for the system is negative. During the remaining two months
(usually May and June), heavy influx of water to the mill
tailing ponds from melting snow accumulations has
necessitated discharge of water from the system. The amount
and duration of this discharge have varied widely from year
to year, depending on meteorological conditions. The
general flows of water during normal operation and during
purge periods are presented schematically in Figure VII-17.
In addition to snow-melt influx, water is drawn for the
system from a well and a small lake (domestic water supply),
mine drainage, and collection structures on a number of area
streams when needed. Diversion structures are currently
being greatly expanded and modified to provide diversion for
most of the area runoff around existing and new tailing
ponds. Drainage from a number of old mine workings (not
owned by the operator of mine 6102) to the tailing-disposal
area has complicated the diversion process. Drainage of low
quality is being segregated and channeled into the tailing
ponds rather than being diverted to the receiving stream.
Water leaves the system through consumptive losses in the
mill, evaporation from pond areas, seepage, and the
aforementioned discharge during peak runoff. With the
completion of diversion structures, discharge will be
substantially reduced, and will occur only during a two
month spring runoff period.
Within the water system, a complex pattern of pumping and
gravity flow is used to provide water treatment and recycle.
Three major impoundments, as well as a number of smaller
impoundments and settling ponds, are currently involved.
A large man-made lake serves as the major holding basin for
water to be recycled to the mill. It receives decant water
from two active tailing ponds. From this lake, water is
pumped to two 7,570-cubic-meter (2,000,000-gallon) holding
tanks at the mill site.
Two mill tailing ponds, 303 hectares (750 acres) and 182
hectares (450 acres) in area, are interconnected and also
connected to the mill water reservoir by a series of decant
structures.
538
-------
Figure VII-17. WATER-FLOW SCHEMATIC DIAGRAM FOR MILL 6102
MINING
ORE
*
MILL
BYPRODUCT
PLANT
DOMESTK
USE
: MILL
TAILINGS
1 „
^ ^^ 1
I
PLANT
TAILINGS
, 1
90.000 m3/day
(25.000.000 gpd)
RUNOFF
AVERAGE FOR 45 DAY
PURGE PERIOD |
89.000m3/d»v
(25.000.000 gpd)
RANGE OF |
0 to 140.000 m3/day |
10 to 38.500.000 gpd)
_J '
1
RUNOFF
3.600 mj/d*v
(1,000.000 gpd I
AREA DRAINAGE
LEGEND
. NORMAL OPERATION FLOW
PURGE-WATER FLOW (INTERMITTENT)
539
-------
Tailing ponds have not been treated with any deliberate
sealant. Seepage through the toe dam is collected in
impoundment ponds and pumped back up to the tailing ponds.
The allowance of seepage in this fashion is intended to
limit hydrostatic pressures on the dam and enhance safety.
Mine water is treated by lime-slurry addition in lagoons
before being pumped to the tailing pond and entry into the
mill water system. About 1,364 kg (3rOOO Ib) per day of
lime are consumed in treating the average mine water flow of
3,600 cubic meters/day (700 gpm) .
Construction of a major new tailing pond is presently under-
way. This pond will have an area of 485 hectares (1,200
acres) and is expected to serve the mill for the next 35 to
50 years. Concurrent with this tailing-pond construction, a
number of supporting projects are underway, including
development of the extensive diversion structures mentioned
previously.
Samples were collected at a number of points in the water-
management system, both during normal total-recycle
operation and during spring runoff. Spring-runoff samples
were, however, atypical due to ice damage to a decant tower
shortly before the site visit. This resulted in a sudden
and rapid purge of the tailing pond. Only a small decand
flow was occurring during the visit, and this was recycled
to the tailing pond. Table vil-31 presents results of
analyses of tailing-pond decant during normal zero-discharge
operation and also shows the concentration of pollutants in
mill recycle water after further settling. Table VII-32
presents results of sampling during spring runoff as well as
company data for discharge quality and calculated waste
loads. Raw waste characteristics and loadings for mill 6102
are presented in Section V.
comparison of data in Tables VII-31 and VII-32 shows that
appreciably higher concentrations of many pollutants are
observed in the effluent streams during purge periods than
are found in the tailing ponds during normal operation.
This flushing effect—presumably, resulting from flows
higher than the design capacity of the treatment system—
negates, to a large extent, the benefits derived from
recycle in terms of removal of many pollutants. As a
result, yearly average effluent loads per ton of ore are, in
most cases, comparable to those achieved at mill 6101
without recycle from the tailing pond. Significant
advantage is seen in the recycle system, however, in the
removal of pollutants such as TDS, which are not effectively
5UO
-------
TABLE VI1-31. CHEMICAL COMPOSITION AND CALCULATED WASTE LOAD FOR
MILL 6102 TAILING-POND SURFACE WATER. WITH ANALYTICAL
DATA FOR MILL-RESERVOIR WATER
PARAMETER
TSS
TOS
Oil *nd Greeie
COO
At
Cd
Cu
Mn
Mo
Pb
V
Zn
Fe
Cy*nid*
Fluoride
CONCENTRATION
tmg/ei
-
1.940
0
11.9
0.01
<0.01
0.04
3.2
12.5
<0.02
<0.5
0.10
2.05
0.02
14.9
TAILING-POND SURFACE WATER
TOTAL WASTE ' — — —
kg/day
-
175.000
0
1.070
0.90
< 0.90
3.6
288
3.600
< 1.8
<45
9.0
180
1.8
1.340
lb/d«y
-
390.000
0
2.400
2.0
< 2
7.9
630
7,900
< 4
< 100
20
400
4.0
2.900
CALCULATED WASTE LOAD
per unit on milled
kj/1000 metric ton*
-
4.500
0
27
0.023
< 0.02
0.092
7.4
92
< 0.05
< 1
0.23
4.6
0.046
34
»>/ 1000 rirart ton*
-
9,000
0
54
0.046
<0.05
0.18
IS
180
<0.09
<2
0.46
9.2
0.092
69
MILL RESERVOIR
WATER
CONCENTRATION
1J7
1,833
21
1
9.96
4.40
0.58
< 0.01
19.09
0.129
-
20.7
AVERAGE TOTAL
WASTE FOR 43 DAY
DISCHARGE PERIOD
kg/d*v
12,000
150,000
1,900
81
890
390
52
<0.8
1.700
11
-
1.900
Ib/day
27,000
320.000
4.100
180
1.900
890
110
< 2
3.700
25
-
4,100
AVERAGE WASTELOAD
FOR 45 OAV DISCHARGE PERIOD
ptr unit or* milled
kg/1000 metric tons
310
3.700
48
2.1
23
9.7
1.3
<0.02
44
0.29
-
48
to/ 1000 short ton*
620
7,500
97
4.2
45
19
2.6
<0.05
88
0.58
-
97
541
-------
removed by the standard alkaline precipitation and settling
treatment. Significantly greater advantage is expected to
be realized from the recycle system as further development
of diversion ditches appreciably decreases the volume of
purge flow, resulting in improvements in quality, as well as
decreased quantity, of effluent.
A portion of the mill effluent stream was treated in an ion-
exchange pilot plant for molybdenum removal. The pulsed-bed
pilot plant was operated extensively, producing an effluent
consistently below 2 mg/1 molybdenum concentration.
Representative feed and effluent analysis data are shown
below.
Molybdenum Ion Exchange Pilot Plant Data (1975)
Concentration (mg/1)
Date Feed Effluent Eluate
7-25 20.5 1.18 16,1UO
7-29 23.0 0.91 16,045
7-30 22.4 1.38 16,568
8-1 24.4 1.76 18,090
8-2 19.5 1.14 12,930
8-6 22.0 1.38 17,484
Average 22.0 1.29 16,230
A saleable molybdenum product may be recovered from the
highly concentrated eluate stream, offsetting the costs of
the ion-exchange operation. Early results indicated that
breakeven--or even profitable—operation may be possible.
Mill 6106. This operation is engaged in the processing -of
nickel ore (garnierite) to produce ferronickel. Mill 6106
is located in Oregon and processes approximately 4,535
metric tons (5,000 short tons) of ore per day.' This mill is
representative of physical ore processors.
•
Water used in beneficiation and smelting of nickel ore at
mill 6106 is extensively recycled, both within the system
and from external water treatment. The bulk of the plant
water use is in the smelting operation, since wet-
beneficiation processes are not practiced. Water is used
for ore-belt washing, in scrubbers on ore driers, in
cooling, and for slag granulation. Water recycled within
the process is treated in two settling ponds, arranged in
series. The first of these, 4.8 hectares (12 acres) in
area, receives a process water influx of 12.5 cubic meters
542
-------
(3,300 gallons) per minute, of which 9.9 cubic meters (2,600
gallons) per minute are returned to the process. Overflow
to the 5.2-hectare (13-acre) second pond amounts to 1.2
cubic meters (320 gallons) per minute. This second pond
also receives runoff water from the open-pit mine site which
is highly seasonal, amounting to zero for approximately six
months and reaching as high as 2,200 cubic meters (580,000
gallons) per day during the (winter) rainy season. The
lower pond has no surface discharge during the dry season,
inputs being balanced by evaporation and subsurface flow to
a nearby creek. A sizeable discharge results from runoff
inputs during wet weather. Average discharge volume over
the year amounts to 460 cubic meters (120,000 gallons) per
day.
This mill was visited during a period of zero discharge, and
samples collected reflect this condition. Samples were
collected from the influent to the first settling pond and
from its overflow, as well as from the surface waters of the
lower settling pond. Analytical data for the influent to
the treatment system are reported in Section V. Data for
influent to the second settling pond from the first pond,
and for its surface waters, are presented in Tables VII-33
and VII-34. In general, the analyses of these samples were
in agreement with data furnished by the company for
corresponding conditions. In Table VII-35, average effluent
loads based on company data for the period of discharge are
furnished. Since influent from mine runoff could not be
determined, no accurate measure of treatment effectiveness
is available. It is evident, however, that effluent loads
are quite low.
As Table VII-33 shows, the first settling pond alone is
highly effective in reducing concentrations of heavy metals
in the effluent stream. The recycle of substantial portions
of the process water delivered to this pond still further
diminishes the effluent load. The surface discharge from
the second settling pond is lower in most metals than the
overflow from the first pond, even though substantial mine
runoff also enters the second pond. The alkaline pH
(average of 8.7) prevalent in these basins enhances
treatment effectiveness in retaining heavy metals.
Mill 6107. At this operation, vanadium is recovered from
non-radioactive ore in a hydrometallurgical operation
involving salt roasting, leaching, solvent extraction, and
precipitation. Approximately 1,140 metric tons (1,250 short
tons) of ore are processed per day, requiring the use of
7,600 cubic meters (1,900,000 gallons) of process water. At
543
-------
TABLE VII-33. CHEMICAL COMPOSITION AND TREATED WASTE LOADS FOR
OVERFLOW FROM FIRST SETTLING POND AT MILL 6106
PARAMETER
Cd
Co
Cu
F«
Mn
Ni
Pb
Zn
CONCENTRATION
(mt/SL
<;o.oi
<-0.05
< 0.02
0.95
0.02
0.07
<0.1
0.03
TOTAL WASTE
kg/day
C0.02
<0.08
<0.03
1.4
0.03
0.11
<0.2
0.045
Ib/day
< 0.04
< 0.02
< 0.07
3.1
0.066
0.24
< 0.4
0.099
WASTE LOAD
p«r urut or* milted
kg/1000 (TMtrictons
< 0.004
<0.02
< 0.007
0.31
0.0066
0.024
<0.04
0.0099
Ib/ 1000 short tons
< 0.009
< 0.04
< 0.01
0.62
0.013
0.048
<0.09
0.020
TABLE VII-34. CHARACTERISTICS OF SURFACE WATER FROM
SECOND SETTLING POND AT MILL 6106
PARAMETER
TSS
TDS
Oil and C'**u
Cd
Cu
ft
Mn
Ni
n>
in
CONCENTRATION
I"*/ l\
6.2
184
2.7
< O.OOS
< 0.02
0.47
<• 0.02
0.03
< 0.05
0.009
TOTAL WASTE
k«/d*y
24
as
1.2
< 0.002
/1 000 *ori torn
13
37
0.53 •
< 0 0009
< 0004
0097
< 0004
OOOU
< 0 09
00018
pw IHIII product
l«»/1000 nwinc tont | ib/1000 then ton*
35
1.000
69
2.000
• 4 i 29
< 0 02
< 0.1
< O.OS
<02
26 ' 5.2
«; o.i
0.18
< 2
0.05
< 0.2
0.36
< 5
0 10
544
-------
TABLE VI1-35. CHEMICAL COMPOSITION AND TREATED WASTE LOADS FROM
FINAL EFFLUENT FOR MINE/MILL 6106 DURING RAINY
SEASON (COMPANY DATA)
PARAMETER
TSS
TDS
Cu
F«
Mn
Ni
Zn
CONCENTRATION*
-------
this operation, representative of the leaching-mi11
subcategoryf three distinct mill wastewater streams are
discharged.
Two of three effluents associated with mill 6107 contain
primarily noncontact water. One is primarily spring water
and natural drainage, with some infiltration from a process-
water reclamation pond and occasional spills of process
water. The other receives non-contact cooling water.
Treatment of these waste streams consists only of
segregation from process water and area runoff. Analytic
data for these effluents are presented in Tables VII-36 and
VII-37.
The main wastewater stream from mill 6107 receives inputs
from several process units and air-pollution control
devices, as well as contaminated drainage from the mill
area. Essentially all streams entering this waste stream
bear very high concentrations of dissolved salts, as well as
a variety of other contaminants, including ammonia and
various heavy metals. The complex system of inputs and
treatment and holding ponds feeding this discharge is
illustrated in Section V. The main process effluent from
washing, leaching, and solvent extraction is treated by
ammonia addition prior to discharge to a 5.3-hectare (13-
acre) holding pond, where it is joined by scrubber bleed
water from ore dryers and treated sanitary wastewater, both
of which have first been treated for solids removal in a
holding pond. Bleed water from a roaster/scrubber is
treated- by settling in a primary pond before delivery to a
2.8-hectare (7-acre) holding pond, adjacent to that
containing process effluent. Discharge from these two ponds
is staged to avoid the formation of calcium sulfate
precipitates, which would result from their combination.
Further, discharge is adjusted by impoundment in accordance
with flow in the receiving water to comply with permit
stipulations on the maximum allowable chloride increase in
the receiving water (25 mg/1). The volume of this effluent
is limited somewhat by recycle of water from the tailing
pond to the washing circuit, recycle within the solvent-
extraction/precipitation operation, and recycle of scrubbing
water to the greatest extent practical, in general, further
reuse of water is limited by the extremely high
concentrations of dissolved solids in the effluent water.
Data for the process wastewater after ammonia treatment, and
for the drier scrubber bleed after solids removal, are pre-
sented in Tables VII-38 and VII-39. The two waste streams
are combined in one holding pond for staged discharge.
546
-------
TABLE VI1-37. CHEMICAL COMPOSITION AND WASTE LOADING FOR
COOLING-WATER EFFLUENT AT MILL 6107
(COMPANY DATA)
PARAMETER
PH
TSS
TOS
Oil and Grease
COO
Ammonii
As
Cd
Cr
Cu
MM
fwtn
Mo
Pb
Zn
Fe
Fluoride
CONCENTRATION
(mg/4)
7.2*
20
695
< 1
15
10
0.010
<0.01
<0.01
< 0.01
0.54
<0.10
< 0.01
0.18
< 0.10
< 1
TOTAL WASTE
kg/day
-
42
1.500
< 2
32
21
0.021
< 0.02
<0.02
<0.02
1.1
<0.2
<0.02
0.38
<0.2
<2
Ib/day
-
92
3,300
< 4
70
46
0.046
< 0.04
< 0.04
<0.04
2.4
< 0.4
< 0.04
0.84
< 0.4
< 4
WASTE LOAD
per unit or* milled
kg/1000 metric tens
-
37
1,300
< 2
28
18
0.018
< 0.02
<0.02
-------
TABLE VI1-38. CHEMICAL COMPOSITION AND WASTE LOADING FOR
PROCESS EFFLUENT AFTER AMMONIA TREATMENT
AT MILL 6107
PARAMETER
PH
TDS
Oil and Grease
COD
As
Cd
Cr
Cu
Mn
Mo
Pb
V
Zn
Fe
Fluoride
CONCENTRATION
(mg/e)
INWASTEWATER
8.3*
40,284
5
443
0.13
0.039
0.2
0.13
52
< 0.1
< 0.05
31.5
0.47
0.3
4.55
TOTAL WASTE
kg/day
—
85,000
11
930
0.27
0.082
0.42
0.27
109
<0.2
<0.1
66
0.99
0.63
9.6
Ib/day
—
190,000
24
2,000
0.59
0.18
0.92
0.59
240
< 0.4
< 0.2
145
2.2
1.4
21
WASTE LOAD
per unit ore processed
kg/1000
metric tons
_
75,000
10
820
0.24
0.072
0.37
0.24
96
<0.2
<0.1
58
0.87
0.56
8.5
lb/1000
short tons
_
150,000
20
1,640
0.48
0.144
0.74
0.48
192
< 0.4
< 0.2
116
1.74
1.12
17
'Value in pH units
548
-------
TABLE VII-39. CHEMICAL COMPOSITION AND WASTE LOADING FOR
DRIER SCRUBBER BLEED WATER AFTER SETTLING
TREATMENT AT MILL 6107
PARAMETER
PH
TDS
Oil and Grease
COD
As
Cd
Cr
Cu
Mn
Mo
Pb
V
Zn
Fe
Fluoride
CONCENTRATION
(mg/£)
IN WASTE WATER
7.7"
10.852
3
34.27
<0.07
< 0.005
0.1
0.08
13.0
<0.1
<0.05
37.5
0.17
0.75
1.2
TOTAL WASTE
kg/day
—
10,000
2.8
32
<0.07
<0.05
0.094
0.075
12
<0.09
<0.05
35
0.16
0.71
1.1
Ib/day
—
22,000
6.2
70
<0.15
<0.1
0.21
0.17
26
<0.2
<0.1
77
0.35
1.6
2.4
WASTE LOAD
per unit ore processed
kg/1000
metric tons
—
8,800
2.5
28
<0.06
< 0.004
0.083
0.066
11
<0.08
<0.04
31
0.14
0.63
0.97
lb/1000
short tons
—
16,600
5
56
<0.12
< 0.008
0.166
0.122
22
<0.16
<0.08
62
0.28
1.26
1.94
'Value in pH units
549
-------
Since this pond was not discharging during sampling, only
company data are presented in Table VII-HO.
Table VII-41 presents data for treated effluent from the
holding pond receiving wastewater from roaster/scrubbers
after primary settling. Table VII-42 presents additional
company data for the same discharge. Average
characteristics of total process effluent (company data) are
presented in Table VII-43.
Mill 6104. At mill 6104, a complex ore is processed by
flotation and leaching operations to yield molybdenum and
copper concentrates and ammonium paratungstate. The mill is
located in California. Mill wastewater is treated by lime
addition to a pH of 9.5 and subsequent impoundment in a
tailing pond, from which clarified water exits by
percolation and evaporation. Treatment practiced on
segregated waste streams from the leaching and solvent-
extraction processes is representative of advanced treatment
applicable to leaching operations. Waste streams from
chemical processing of scheelite flotation concentrates are
treated by distillation in a two-stage
evaporator/crystallizer and by stripping with air for
ammonia removal prior to combination with tails from other
operations for liming and delivery to the tailing ponds.
The air stripper operating at this facility treats
approximately 0.27 cubic meters per minute (70 gal per
minute) of ammonia-laden wastewater in a packed tower
achieving an average of 70% removal of ammonia. The ammonia
which is removed is currently released to the atmosphere.
Repeated sampling at this site showed stripper performance
to be variable—apparently, depending strongly on pH control
of the feed solution. Typical feed and effluent ammonia
concentrations are 300 mg/1 and 80 mg/1, respectively.
Samples of the solvent-extraction effluent and the
precipitation waste before treatment were not obtained.
Since there was no surface discharge, and since there was no
pool of water in the tailing pond at the time of the visit
to this site, no sample of clarified mill discharge water
could be obtained. Limitations met by this discharge may be
assumed to be indicative of its quality and are tabulated
below.
550
-------
TABLE VI140. CHEMICAL COMPOSITION AND WASTE LOADING FOR
HOLDING-POND EFFLUENT (PROCESS WATER AND
DRIER SCRUBBER BLEED) AT MILL 6107
(COMPANY DATA)
PARAMETER
Ammonia
Ca
Cd
Cu
Mn
Mo
V
Zn
Ni
Fe
Sulfate
Chloride
CONCENTRATION
(mg/Z)
IN WASTE WATER
2,030
450
0.08
0.23
38
16
31
0.83
0.96
0.23
12,200
7,800
TOTAL WASTE
kg/day
6,500
1,400
0.26
0.73
120
51
99
2.7
3.1
0.73
39,000
25.000
Ib/day
14,000
3,100
0.57
1.6
260
110
220
5.9
6.8
1.6
86,000
85,000
WASTE LOAD
per unit ore processed
kg/1000
metric tons
5,600
1,200
0.23
0.64
110
45
87
2.4
2.7
0.64
34,000
22,000
lb/1000
short tons
11.200
2.400
0.46
1.28
220
90
174
4.8
5.4
1.28
68.000
44.000
551
-------
TABLE VII-41. CHEMICAL COMPOSITION AND WASTE LOADING FOR
ROASTER SCRUBBER BLEED WATER AFTER SETTLING
AT MILL 6107
PARAMETER
PH
TSS
TDS
Oil and Grease
COD
At
Cd
Cr
Cu
Mn
Mo
Pb
V
Zn
Fa
Fluoride
CONCENTRATION
(mg/£)
INWASTEWATER
7.9*
12T*
57,690
3
1,859
< 0.07
< 0.005
0.2
< 0.03
5.5
< 0.1
< 0.05
15
5.95
0.25
6.0
TOTAL WASTE
kg/day
_
209
100,000
5.2
3,200
<0.1
< 0.009
0.35
<0.05
9.5
<0.2
<0.09
26
10
0.43
10
Ib/day
—
460
220,000
11
7,000
< 0.3
< 0.02
0.77
< 0.1
21
< 0.4
< 0.2
57
23
0.95
23
WASTE LOAD
par unit ore processed
kg/1000
metric tons
-
180
88,000
4.6
2,800
< 0.09
< 0.008
0.31
<0.04
8
<0.2
<0.08
23
8.8
0.38
8.8
lb/1000
short tons
—
360
176,000
9.2
5,600
<0.18
< 0.016
0.62
<0.08
16
<0.4
<0.16
46
17.6
0.76
17.6
• Value in pH units
•* Company data indicate* this should beat 30 mg/i
(Watte loads are correspondingly high)
552
-------
TABLE VI1-42. CHEMICAL COMPOSITION AND WASTE LOADING FOR
ROASTER SCRUBBER BLEED WATER AFTER SETTLING
AT MILL 6107 (COMPANY DATA)
PARAMETER
Ammonia
Ca
Cd
Cu
Mn
Mo
V
Zn
Ni
Fe
Sulfate
Chloride
CONCENTRATION
imgli)
IN WASTEWATER
360
26,000
0.42
0.31
11
1.1
14
8.4
1.0
0.93
500
36.000
TOTAL WASTE
kg/day
620
45,000
0.73
0.54
19
1.9
24
15
1.7
1.6
820
62.000
Ib/day
1,400
99,000
1.6
1.2
42
4.2
53
33
3.7
3.5
1,900
140,000
WASTE LOAD
per unit ore processed
kg/1000
metric tons
550
40,000
0.64
0.48
17
1.7
21
13
1.5
1.4
760
55,000
lb/1000
short toni
1,100
80,000
1.28
0.96
34
3.4
42
26
3.0
2.8
1,420
110,000
553
-------
TABLE VII-43. CHEMICAL COMPOSITION AND WASTE LOADING FOR
AVERAGE TOTAL PROCESS EFFLUENT AT
MILL 6107 (COMPANY DATA)
PARAMETER
PH
TSS
TDS
Oil and Grease
COO
Ammonia
AJ
Cd
Cr
Cu
Mn
Mo
Pb
Zn
Fe
Fluoride
CONCENTRATION
(mg/Ji)
IN WASTEWATER
6.7*
180
44.000
<1
70
1,200
0.020
0.30
0.090
0.26
28
11
<0.1
4.00
0.50
1
TOTAL WASTE
kg/day
-
890
220,000
<5.0
340
5,900
0.098
1.5
0.44
1.3
140
54
<0.5
20
2.5
4.9
Ib/day
—
2.000
480,000
<10
750
13,000
0.22
3.3
0.97
2.9
310
120
< 1
44
5.5
11
WASTE LOAD
per unit ore processed
k 9/1 000
metric tons
-
780
190,000
< 4
300
5,200
0.09
1.3
0.39
1.1
120
48
< 0.4
18
2.2
4.3
Ib/IOOG
short tons
—
1,560
380,000
< 8
600
10,400
0.18
2.6
0.78
2.2
240
96
< 0.8
36
4.4
8.6
•Value in pH units
554
-------
Concentration
Parameter (mg/1)
Sodium 600
Chloride 1000
Sulfate 1000
Total Nitrogen 5
(Organic, NH3, W0.3)
Nitrate 2
These values are consistent with the observed 2,290 mg/1 TDS
content of the combined tailing stream (See Waste Character-
istics , Section V), reflecting the substantial removal of
dissolved salts—especially, sodium sulfate—from the
effluent.
Mercury Ores
Historically, water has found little use in the mercury-ore
mining and dressing industry. In the past, the mined ore
was primarily fed directly into a retort or furnace, and the
mercury was recovered by roasting. When beneficiation has
been employed, it has normally been limited to crushing
and/or grinding. As a result, water-treatment technology or
facilities have not been typically required in this
industry.
Mining Operations. Water is not used in mercury mining
operations and is discharged only where it accumulates as a
result of seepage or precipitation. When mines are not
located adjacent to a mill, or when their effluents (if any)
are to be segregated from the mill wastewater, it will be
necessary to discharge these waters, unless total
impoundment is possible. Treatment of this wastewater is
necessary for removal of suspended solids and heavy metals.
The mercury ion is best treated for removal by sulfide
precipitation. Other technologies for the removal of heavy-
metal waste constituents are the chemical precipitation
and/or flocculation methods and settling ponds, which have
been discussed previously in this section.
Milling Operations- Mercury ore can be concentrated by
gravity methods and by froth flotation. However, these
methods have not been employed extensively, since direct
555
-------
retorting of the ore is an efficient and effective method
for recovering mercury. In addition, most mercury ores are
not amenable to gravity separation, since mercury minerals
tend to be crushed finer than the gangue, with resultant
excessive loss of these minerals in the slimes. However, as
lower-grade mercury ores become mined, it is expected that
beneficiation processes will become increasingly important
and necessary in this industry.
Mill 9201 . This operation is located in the state of
California. Operation of this mill is seasonal, with
closure of the mine/mill during the rainy season (winter),
when muddy roads make access difficult. A sandstone ore
containing cinnabar (HgS) is mined from an open pit and
brought to the mill. During 1973, 30,000 short tons (27,210
metric tons) of ore were milled by gravity methods to
produce a cinnabar concentrate. No discharge results from
the mine.
This mill operates on a total-recycle system, with no
discharge resulting. Water is used in a gravity-separation
process, and the mill tailings are discharged at a rate of
1,665 cubic meters (136,000 gallons) per day to a 1-hectare
(2,5-acre) tailing pond. Seperan NP-10, a flocculant, is
added to the waste stream to increase solids settling.
Clarified pond water is decanted and returned to the mill
for reuse. About 16 cubic meters (4,300 gallons) per day of
makeup water are required, and this is obtained from a
nearby reservoir.
The efficiency of the treatment system is presented in Table
VII-44. No waste loadings have been computed, because no
discharge results from this operation.
Mine/Mill 9202. This operation, located in Nevada, has been
actively producing only since early 1975. The ore, which
consists of cinnabar (HgS) and corderoite (Hg3_S2C12_),
disseminated in ancient lake-bed sediments (primarily
clays), is concentrated by flotation. This ore is mined by
open-pit methods, and at present, no water accumulates in
the mine which would necessitate a discharge.
Mill tailings are presently impounded in four 20-hectare
(50-acre) ponds for retention of solids and evaporation of
wastewater. The operators of this irill initially proposed
to recycle clarified decant from these ponds back to the
mill. However, difficulty in obtaining a clarified decant
has been experienced, and, as a result, recycle has not yet
been feasible on a large scale. The problem stems from the
556
-------
TABLE VII-44. CHEMICAL COMPOSITIONS OF MILL WASTEWATER AND
TAILING-POND SURFACE WATER AFTER TREATMENT
AT MINE/MILL 9201 (NO DISCHARGE, RECYCLE OF
TREATED WATER)
PARAMETER
PH
TSS
TDS
COO
Oil and Grease
Si02
Al
Cd
Cr
Cu
Total Fe
Pb
Total Mn
Hg
Ni
Sr
Zn
Sb
Mo
Fluoride
Sulfate |
II CONCENTRATION (mg/£)
|| MILL WASTEWATER
6.5*
154,000
290
42.79
<1
9.8
10.4
< 0.005
0.04
<0.02
<0.5
' <0.1
50.0
—
0.68
0.60
0.14
<0.5
<0.2
0.61
100
TAILING-POND
DECANT
6.5*
76
144
27.23
2
9.3
0.5
< 0.005
0.02
<0.02
0.87
<0.1
0.10
0.125
0.10
0.10
0.03
<0.5
<0.2
0.83
75
Value in pH units
557
-------
presence of montmorillonite clay in the ore body. This
material becomes suspended during milling activities and is
very slow to settle. Flocculants have been used to aid
settling but have not, to date, been successful. Reuse of
the pond water having the quality presently obtained would
reportedly result in a lower percentage of recovery, lower-
grade concentrate, and lower daily rate of production (less
ore milled/day). For these reasons, recycle has not been
attempted on a large scale.
The quality of the wastewater prior to and following
settling is presented in Table VII-45. No waste loadings
have been computed, as no discharge results from this
operation.
Uranium, Radium, and Vanadium Ores
The discussion that follows describes treatment and control
technology in current use in the uranium, radium, and vana-
dium (byproduct recovery under NRC licensing) ore mining and
dressing industry. Aspects of treatment and control which
are characteristic of this category are described.
Mining Operations. Uranium mining in the U.S. is conducted
primarily in the arid states. Approximately 60 percent of
the facilities contacted in the course of this study
indicated that they have no discharge. Where it is
practical, mine wastewater is used as process feed water for
milling. It then becomes a mill effluent and is impounded,
and subsequently is lost to evaporation and seepage. At the
operations employing the best treatment and control
technology in this industry, uranium values are frequently
extracted from minewater by ion exchange (IX) methods. In
addition, where dry mines are proximate to mines discharging
wastewater, the discharge is often recycled to the dry mines
to effect in-situ leaching. Evaporation and other losses in
this process often reduce water vclume to a point where no
discharge results. Further treatment of wastewater destined
for natural waterways always includes settling.
High values of Ra226 observed in mine wastewater indicate
that coprecipitation treatment is necessary to reduce radium
values to acceptable values. Values of Ra226 in mine waste-
water currently range from approximately 100 to 400
picocuries per liter, while technology currently being
employed in mill wastewater treatment nearly always attains
reduction to a level of below 3 picocuries per liter; under
favorable conditions existing in well-designed treatment
systems, levels of 1 picocurie per liter have been obtained.
558
-------
TABLE VII-45. CHARACTERIZATION OF MILL WASTEWATER
AND TAILING-POND SURFACE WATER FOLLOWING
SETTLING AT MINE/MILL 9202
PARAMETER
PH
TSS
COD
Cd
Cr
Co
Cu
Fe
Pb
Mn
Ni
Sb
Zn
Hg
11 CONCENTRATION (mg//)
MILL
WASTEWATER
8.2t
—
—
0.42
3.6
1.7
1.3
2,880
0.58
7.0
2.4
3.76
1.1
27.5
TAILING-POND
DECANT'
8.4t
—
94
< 0.005
0.015
<0.05
0.26
1.7
0.02
0.034
0.021
0.23
0.10
0.014
•Sample collected from pond at point of decant when decant of water for recycle is
employed.
* Value in pH units.
559
-------
In addition, similar technology applied to a mine has
demonstrated reduction to less than 3 pCi/1 regularly
obtainable, with levels below 1 pci/l under favorable
conditions.
To employ treatment technology recommended here for radium
reduction, in mine wastewaters, it may sometimes be
necessary to add sulfate ion to the wastewater stream to
allow coprecipitation with barium chloride. If ferrous
sulfate is added at a level of 100 mg/lr some molybdenum is
also coprecipitated with ferric hydroxide, and sulfate ion
is liberated to effect radium coprecipitation.
Mine 9401 . This operation currently obtains uranium ore
from four underground mines in New Mexico, one of which
contributes a significant amount of mine water to adjacent
mines after treatment by ion exchange (for uranium
extraction) for in-situ leaching. The total flow in the
ion-exchange plant is 9,300 cubic meters (2,455,200 gallons)
per day. Evaporation losses in surface distribution
channels apparently cancel the excess influx from the one
wet mine, so no discharge results. If there were a
discharge from the ion exchange system, this discharge would
exhibit high levels of suspended solids (530 mg/1) and COD
(750 mg/1) .
The ion-exchange process at this operation illustrates that
an IX system which is optimized for one particular ion
(e.g., uranyltrisulfuric ion) is relatively ineffective for
removing even similar ions. As shown in the table below,
only vanadium follows uranium in being extracted.
Element In Out
U 25 1
As 0.03 0.04
Pb 0.02 0.11
V 1.0 less than 0.5
Fe 0.47 0.51
Mo 0.5 0.77
Be 0.01 0.01
Al 0.55 0.55
B 0-15 0.19
Ca 93 96
Mg 45 45
K 25 25
Na 200 200
Sr 0.87 0.124
Zn 0.034 0.064
560
-------
However, in this case, uranium and vanadium are reduced to
levels of 1 mg/1 or less. With some compromises in
treatment efficiency for uranium and vanadium, other metals
can be removed.
Mine 9HQ2 . A group of several mines discharging 11,500
cubic meters (3,036,000 gallons) of water per day is located
near a mill which uses approximately two-thirds of the mine
discharge as mine process water. This operation is also
located in New Mexico. Two types of treatment are used. At
one mine, mine water is treated for suspended-solids removal
by a series of three settling ponds and then is discharged.
Table VII-46 presents the chemical compositions of raw and
treated wastewaters resulting from this mine.
A second group of mines feeds a treatment system consisting
of an ion-exchange plant (for removal of uranium values).
Discharge from the ion-exchange plant splits with
approximately 23 percent being discharged and the remainder
entering a holding pond to be used as mill make-up water.
(See Figure V-34b.)
Initial concentrations varying from 2 to 12 mg/1 of U3p£
were treated by use of an eight-column anionic-exchange
system which recovers 98 percent of the influent uranium.
At lower concentrations, this process is known to be less
effective than at higher concentration. An example of this
loss efficiency can be cited for the case of mercury removal
by ion exchange methods, as shown in Figure VII-18. The
fact that uranium shows a similar behavior is illustrated by
the data points for uranium that have also been plotted on
this graph. Additional data on the efficiency of IX
processes are available to members of the industry. These
data currently are proprietary, for competitive reasons.
Table VII-47 presents the results of treatment by ion
exchange and settling at.mine 9402(002).
Millina operations. Treatment for suspended-solid removal,
neutralization of pH, precipitation of hazardous pollutants,
coprecipitation of parameters in very low concentrations,
and for the recovery of values exists in milling operations
of the uranium industry. Some treatment is used to permit
•^sci-arq* while, in most instances, treatment facilitates
recycle and/or impound. Approximately 90 percent of the
uranium milling industry has no point discharges. Two of
the remaining milling operations have lateral seepage from
tailing impoundments that is collected and discharged. One
operation is currently modifying its entire process to
561
-------
TABLE VII-46. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AT MINE 9402 (001)
PARAMETER
PH
TSS
COO
TOC
As
Cd
Cr
Cu
Hfl
Mo
Ni
Pb
V
Zn
Ra
U
CONCENTRATION (mg/A)
RAW WASTE WATER
*
8.1
289
<10
45
0.02
M.
^
<0.5
—
0.5
—
0.13
2.1
—
230"*
4.14
TREATED WASTEWATER
•
7.4
17
15.9
195
0.02
0.003*
0.01 f
0 to 0.01 f
0.00 1f
0.8
0.04t
0.1
1.7
0.002f
65»*
1.1
» + **
Value in pH units Company data Value in picocunes/£
Figure VIMS. ION EXCHANGE FOR MERCURY AND URANIUM AT LOW
LOADINGS AND CONCENTRATIONS
1
0.01
0.1
1.0 10 100
EQUILIBRIUM CONCENTRATION (mg/£)
1000
10,000
562
-------
TABLE VIM7. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AT MINE 9402 (002)
PARAMETER
PH
TSS
COO
TOC
As
Cd
Cr
Cu
Hg
Mo
Ni
Pb
V
Zn
Ra
Th
U
CONCENTRATION (mg/£)
RAW WASTEWATER
7.7'
-
734
20.5
<0.01
<0.02
<0.02
<0.5
0.0004
0.5
<0.01
0.18
<0.5
<0.5
69*
<0.1
13.31
DISCHARGE FROM
TREATMENT (IX)
8.1*
-
405
20.5
0.02
<0.02
<0.02
<0.5
0.0004
0.1
<0.01
0.11
<0.5
<0.5
105»
<0.1
4.55
*Valu« in pH units
•Vilu« in picocuriM/X
563
-------
attain zero discharge. This is expected to be accomplished
by increased use of recycling and by minor process
modifications.
Mill 9U01. This operation is located in New Mexico and
extracts uranium and vanadium byproducts by alkaline
leaching processes. (See Section III.) The mill has no
point discharge. The mill incorporates two recycle loops:
one involving recarbonization of leach, which leaves all
water characteristics relevant to discharges essentially
unchanged, and another loop that returns decant water from
tailings by means of an ion-exchange column. The IX process
recovers uranium that was rejected to tailings and
solubilized there; however, this loop also does not improve
water quality.
As discussed in Section III/ the alkaline-leach process used
at this mill involves a purification step that adds sodium
and sulfate ions to the water. If water were recycled
indefinitely, these ions would increase in the tailing
ponds. Evaporation there would eventually permit
crystallization of sodium sulfate, and the formation of
crystals in other portions of the loop would prevent the use
of the recycle liquor, even for such operations as repulping
of tailings.
Certain measures, which allow recycling of a significant
portion of the flow, must be taken to separate sodium
sulfate resulting from the purification process from the
other recyclable liquors. A separate, lined evaporation
pond would serve this function.
Mill 9U02. The mines and mill are located near each other
at this operation in New Mexico, and some water from the
mines is used in the acid-leach process, while the remainder
is discharged. The mill itself has no pcint discharge.
Like most acid-leach operations, the mill cannot practice
recycle from tailing decant liquor (without treatment by
reverse osmosis) because high concentrations of solutes
interfere with the process of concentrating values. The
effect of evaporation on the tailings that are pumped
through a sequence of four sequential ponds is illustrated
in Figure VTI-19. The initial drop is due to chemical
precipitation and is followed by a rise in concentration due
to a redissolution in acid concentrated by evaporation of
water. If vertical seepage or discharge were to result from
this operation, neutralization of the acid waste liquors to
564
-------
Figure VII-19. CHEMICAL CHANGES IN A SEQUENCE OF TAILING
IMPOUNDMENTS AT MILL 9402
3.0 r
ALL HEAVY-METAL
MIL WASTEWATER
INFLUENT
POND-1
EFFLUENT
POND-2
EFFLUENT
LOCATION
POND-3
EFFLUENT
POND-5
EFFLUENT
565
-------
prevent discharge of innocuous salts and resolubilized heavy
metals would be necessary.
Lateral seepage from the first tailing pond is controlled by
pumping from a second seepage collection "pond," at the toe
of the dam, to safer storage in a third pond, which is at a
higher elevation than the first tailing pond. From there,
water may be pumped to one of two smaller ponds at even
higher elevation. This arrangement of ponds provides
protection against failure of any one dam, except for the
main tailing dam. Failure of the dams retaining the upper
ponds would dump their contents into the larger, lower
rends, rather than into the environment.
Mill 9403. This mill is located in Utah. Mines supplying
this operation are completely separated from the mill and
were not visited. The mill uses alkaline leach and has
extensive byproduct operations. Its discharge to a river is
expected to be reduced in volume by a factor of ten or
eliminated in late 1975. Complete recycle is technically
possible but would require expensive alterations to waste-
treatment facilities. Land suitable for construction of a
pond large enough to remove waste liquor by evaporation is
several kilometers away and is located at an elevation
several hundred meters higher.
The present mill treats river water (to reduce hardness),
raw wastewaters (to remove suspended and settleable solids),
and decant water from the tailing pond (to remove radium by
BaC12 coprecipitation). The water-softening scheme is not
properly an effluent treatment, but it illustrates a large-
scale technique for reducing calcium and magnesium, by
reducing calcium carbonate content from approximately 500
mg/1 to 35 mg/1. Table VII-U8 shows the effect of tailing-
pond and coprecipitation treatments on effluent
characteristics.
Mill 9404. This mill, located in New Mexico, is approx-
imately 100 km (60 miles) from the mine that furnishes ore.
The mill uses acid leaching, and recycle is not practical.
A tailing pond, 3 kilometers (2 miles) from the mill,
evaporates wastewater and concentrates the solutes. The
tailing area covers a somewhat porous stratum. For this
reason, a deep well was drilled to a depth of 770 meters
(2,530 feet) into porous strata containing water unfit for
other use, and decant wastewater from the pond is
occasionally injected into this well, following filtering to
566
-------
TABLE VIMS. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AND EFFLUENT WASTE LOADING
AT MILL 9403 (SETTLING AND BaCI2 COPRECIPITATION)
PARAMETER
PH
TSS
COO
TOC
At
Cd
Cr
Cu
Hg
Mo
Ni
Pb
V
Ra
Th
U
CONCENTRATION (mff/H)
RAW
WASTEWATER
9*
111,000
27.8
<1
1.4
0.04
<0.02
1.1
0.0016
0.25
0.52
0.69
<0.5
111'
—
3.9
TREATED
EFFLUENT
9«
31
71.4
20
2.8
<0.02
<0.02
<0.5
0.0002
3.3
<0.01
0.13
7.4
4.091
<0.1
2.5
kg/day
-
161
370
100
15
<0.1
<0.1
<2.6
0.001
17
<0.05
0.67
38
21.2"
<0.5
13
EFFLUENT WASTE LOAD
Ib/day
-
354
814
220
33
0.22
0.22
<5.7
0.0022
37
<0.11
1.47
84
-
<1.1
29
kg/metric ton
of concentrate
—
120
270
74
10
-
-
-
0.0007
12
-
0.48
30
15.8"
-
10
Ib/thort ton
of concentrate
_
240
540
148
20
_
_
—
0.0014
24
—
0.96
60
14.4"*
_
21
•Value in pH unit!
Value in picocuries/2
*• Value in microcuries/day
rtValue in microcuriM/metric ton
'••Value in microcuriw/lhort ton
567
-------
remove suspended solids that might plug the well. There is
no point discharge at this mill.
Mill 9405. This mill is located in western Colorado within
a few miles of many small mines yielding uranium and
vanadium ores. The mill uses acid leaching and produces
more vanadium than uranium, with vanadium concentrated by
solvent exchange. Waste liquors from the vanadium process
are evaporated in ponds as are some liquid wastes from
uranium refining. Effluents from yellow cake (uranium)
precipitation and washing are combined with hillside runoff
and treated by barium chloride coprecipitation which reduces
Ra 226 concentrations from a level of about 40 picocuries
per liter (pC/1) to 1 to 3 pC/1 using 0.06 to 0.09 grar
BaClJ2 per liter in the presence of 5000 mg/1 of sulfate ion.
Metal Ores, Not Elsewhere Classified
This group contains ore mining and dressing operations which
vary considerably in their size, methods of mining and bene-
ficiation, and location. Relatively few operations are
represented in this diverse group, with primary production
for antimony, beryllium, platinum, and rare-earth ores
represented by one mine and mill each. Tin and zirconium
ores are obtained as byproducts, while antimony is also
obtained as a byproduct of both silver mining and milling
and lead and zinc smelting.
Antimony Ores
There currently exists only one operation (mine/mill 9901)
which is mining and milling ore primarily for its antimony
content. Mill 9901 discharges tailings from its flotation
circuit to a tailing pond and achieves zero discharge by
impoundment of tailings in this pond. The operators of this
mill also indicate that recycling of tailing-pond process
water would not be expected to pose any problems, should
recycling become desirable at this mill. However, if this
water were to be recycled, additional settling treatment
would be necessary to reduce its slime content. Therefore,
the impoundment area would require either expansion or
redesign to facilitate a recycle system.
No effluents are currently being discharged to the surface
from mine 9901. However, this operation has been active for
only a few (three to five) years; as the mine is developed
more extensively, a discharge may result from the influx of
ground water. If discharged, the mine wastewater may
potentially contain suspended solids and solubilized metals.
568
-------
which will require treatment prior to final discharge of the
effluent. Treatment technologies potentially available for
application at this mine are chemical precipitation and
flocculation methods and use of settling basins, previously
discussed.
Chemical precipitation of metal hydroxides by lime addition
will successfully remove most of the heavy metals (i.e.r
arsenic and zinc) present in this ore body. Lime will also
create the alkaline conditions necessary for the successful
removal of antimony by sulfide precipitation.
Beryllium Ores
Only one operation in the beryllium mining and milling
industry is known to use water in a milling process. The
limited amount of beryl mined domestically is, for the most
part, concentrated by crude hand-cobbing methods. However,
bertrandite, mined from an open pit, is processed at mill
9902 by a sulfuric acid leach process. This mill is
achieving zero discharge by impoundment of the mill tailings
in a tailing pond. Water is removed from the pond by
natural evaporation and possible percolation into the
subsurface. No discharge exists from the open-pit mine at
this time.
Platinum-Group Metals
The bulk of production of the platinum-group metals results
from recovery as byproducts from copper ore during refining
operations. These metals are also being recovered by an
operation (mine/mill 990U) which seasonally mines a placer
deposit in Alaska. This placer, located alongside a major
river, is mined by a dredge, floated on a impoundment con-
structed over the deposit. The heavy minerals are
concentrated by gravity-separation methods; therefore, waste
loading of the process water includes primarily suspended
solids. These process wastes are discharged to the dredge
pond, where some settling of the solids occurs. The
suspended-solid content of the pond water is further reduced
as it filters through a sand barrier prior to final
discharge.
The relatively unsophisticated methods described above are
typical of the best existing treatment at precioos-metal
placer operations. As such, this treatment is designed to
reduce suspended-solid loadings of final discharges. Since
recycle is usually not practicable at a placer operation of
this type, use of the treatment described is necessary.
569
-------
Therefore, efficient treatment can be maximized by
optimizing conditions for settling and/or filtration of the
process wastes. Long-range control of solids should take
the location of the treatment facilities into consideration.
These facilities should, when possible, be located at a
distance from a stream, which would afford protection from
seasonally high waters.
Table VII-U9 presents the chemical composition and treated
waste load for mine/mill 9904.
Ra re-Earth Ores
Currently, only one operation mines a lode deposit for its
rare-earth mineral content. This operation (mine 9903)
mines bastnaesite from an open pit and concentrates the ore
in a flotation circuit. The flotation concentrate is
further upgraded in a leach circuit before final processing
in a solvent-extraction plant. Presently, the flotation
tailings are discharged to a tailing pond, and the clarified
pond water is recycled back into the flotation circuit.
Process wastes from the leach circuit are separately
discharged to an evaporation pond. The efficiency of
tailing-pond treatment of the water to be recycled is
presented in Table VII-50.
The rare-earth mineral monazite is recovered primarily as a
byproduct of titanium operations. Treatment technology
employed at these operations is discussed under Titanium in
this section.
Segregation of Waste Streams. Because mine/mill 9903 is
located in an arid region, water is a scarce commodity at
this site. It is primarily for this reason that water is
recycled from the tailing pond back to the flotation
circuit. The leach-circuit wastes are not combined with the
water to be recycled, as this waste contains very high
dissolved-solid concentrations, which would undoubtedly
cause interference in the flotation circuit. At this mill,
the waste streams have been segregated, then, to facilitate
recycle.
Tin Ores
Tin is obtained as a byproduct of molybdenum mining and
milling at one location in the United States. No separate
discharges result from tin mining or processing.
570
-------
TABLE VII-49. CHEMICAL COMPOSITION OF TREATED EFFLUENT AND
WASTE LOAD FROM MINE/MILL 9904 (PLATINUM)
PARAMETER
COO
TSS
Fe
Pb
Zn
Fluoride
CONCENTRATION (mg/J,)
IN WASTE WATER
7.6
30
0.17
0.01
0.03
0.95
TREATED WASTE LOAD
per unit of ore milled
kg/1000 metric tons
0.11
0.43
0.002
0.0001
0.0004
0.01
lb/1000 short tons
0.22
0.86
0.004
0.0002
0.0008
0.02
TABLE VII-50. CHEMICAL COMPOSITIONS OF RAW WASTEWATER
AND TREATED RECYCLE WATER AT MILL 9903
(NO DISCHARGE)
PARAMETER
PH
TSS
TDS
TOC
Cr
Total Mn
V
Y
La
Ce
Pr
Nd
Sm
Eu
Gd
Th
Fluoride
CONCENTRATION (mg/J.)
RAW WASTEWATER
9.02*
360,000
14.476
3,100
0.35
0.5
<0.3
—
—
«•*•
mm
mm
—
365
TREATED
RECYCLE WATER
758*
17,300
9,576
1,400
0.03
4.5
<0.3
0.014
1.32
2-75
0.27
0.51
41
< 0.001
0.006
< 0.001
55
*Value in pH units
571
-------
Titanium Ores
Titanium ores mined and milled in the United States occur in
two modes: as a hard rock deposit and as placer or heavy-
sand deposits of ilmenite, rutile, and leucoxene. The
methods of mining and beneficiation of both types of
deposits are described in detail in Section III. The
treatment and control technologies employed at exemplary
operations in this ore category are described below.
Mine/Mill 9905. In the U.S., one operation is presently
mining a lode deposit for titanium minerals (primarily,
ilmenite). At this operation, ore mined from an open-pit
mine is crushed and floated to concentrate the ilmer.it.e.
Prior to flotation, magnetite associated with the ilmenite
is magnetically separated from the ore.
Process wastes, largely from the flotation circuit, are
discharged to a formerly used open-pit quarry, which serves
as a tailing pond. Clarified overflow from this pit is
recycled back into the mill circuit. Tailing-pond
treatment-efficiency data are presented in Table VII-51. No
chemicals are added for treatment purposes, although the
process water has an alkaline pH.
Although this mill employs a recycle system, rain and runoff
which collect in the recycle system occasionally result in a
seasonal discharge. Diversion ditching is not presently
used at this mill. If diversion ditching or other systems
were installed to prevent excess water from collecting, a
seasonal discharge might not occur at mill 9905.
Water is currently discharged from open-pit mine 9905.
Prior to final discharge, this water is retained for
settling for a short time in a small pond. Improved
treatment of this mine water could be attained by increased
retention time in a pond, and by treatment with lime or
other precipitating agent to ensure optimum metal and
fluoride removal.
Mine/Mi11s 9906 and 9907. These operations recover titanium
minerals (ilmenite and rutile) and the zirconium mineral
zircon from sand placers. Similar operations also recover
the rare-earth mineral monazite.
As these placer deposits are located inland, the typical
practice is to construct a pond over the ore body and to
mine the placer by dredging. The heavy-mineral sands are
upgraded by gravity methods in a flotation mill, and the
heavy minerals in the bulk concentrate are separated and
concentrated by electrostatic and magnetic methods in a dry
mi 13..
572
-------
TABLE VII-51. CHEMICAL COMPOSITIONS OF RAW WASTEWATER
AND TREATED RECYCLE WATER AT MILL 9905
PARAMETER
Conductivity
Turbidity (JTU)
TSS
TDS
TOC
Oil and Grease
As
Cd
Cr
Cu
Total Fe
Pb
Total Mn
Hg
Ni
V
Ti
Zn
Nitrate
CONCENTRATION imgli)
RAW WASTEWATER
650*
2.2
26,300
518
9.0
2.0
<0.01
< 0.002
0.58
0.43
630
<0.05
5.9
0.004
1.19
2.0
2.08
7.6
0.68
TREATED
RECYCLE WATER
490*
056
2
526
12.5
2.0
0.01
< 0.002
0.02
<0.03
<0.02
<0.05
0.3
< 0.0002
<0.01
<0.5
<0.2
< 0.002
0.50
Value in micromhos/cm
573
-------
Process wastes emanating from the wet mill are discharged to
the dredge pond. However, as discussed in Section V, the
primary waste constituents of the dredge-pond effluents are
the colloidal organic materials, of high coloring capacity,
present in the ore body. These materials are flocculated by
reducing the pH to 3.5 with sulfuric acid. The water then
flows through a large pond system, where the coagulated
sludge settles. The clarified overflow from this system is
neutralized with lime prior to final discharge to the
receiving stream. Both acid and lime are fed by
automatically controlled equipment. Reagents are added to
the waste stream in flumes designed to create turbulent
mixing. The treatment efficiency of this system is
presented in Tables Vll-52 and Vll-53 for operations 9906
and 9907, respectively. Waste-load reduction data are
presented in Tables VII-54 and VII-55.
Potential Control Technology at Sand Placer Operations.
Water used in the wet mill at these placer mines is drawn
from the dredge pond; therefore, in this sense, process
water is recycled. However, some fresh water is required
for use as pump seals, as wash water in the finisher
spirals, or in "laminar flows" (gravity-separation devices),
and this water is drawn from a well.
A degree of waste-load reduction could be achieved by
partial recycle of the treated dredge-pond effluent back to
the wet mill for use in the finisher spirals or laminar
flows. Treated water would be suitable to replace the fresh
water now used Fin the wet mill. The primary reason why
this practice is not currently employed is that water can be
drawn from wells at less expense than required to recycle
treated water.
Zirconium Ores
No primary operations for zirconium ores exist in the United
States. Zirconium is obtained as a byproduct of heavy-
mineral sand placer operations for titanium. No separate
discharge or waste loading can be assigned to this metal.
SUMMARY OF MINE/MILL OPERATIONS EMPLOYING EXEMPLARY
WASTEWATER TREATMENT
Tables VII-56 and VTI-57 present a summary of information
pertaining to mine/mill operations, in all metal-ore
categories, which employ exemplary wastewater-treatment
technology exclusive of zero discharge. These tables
reflect several data sources, including NPDES discharge
57 U
-------
TABLE VII-52. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AT MILL 9906
PARAMETER
PH
Conductivity
Color
TDS
TSS
COD
TOC
Oil and Grease
Al
As
Cr
Cu
Total Fe
Total Mn j
Hg
Ti
Zn 1
CONCENTRATION
-------
TABLE VI1-53. CHEMICAL COMPOSITIONS OF RAW AND TREATED
WASTEWATERS AT MILL 9907
PARAMETER
pH
Conductivity
Color
TDS
TSS
COD
TOC
Oil and Grease
Al
As
Cr
Cu
Total Fe
Total Mn
Hg
Ti
Zn
CONCENTRATION (mg/J.)
RAWWASTEWATER
w
40I.
16,240**
370
209
361.6
321.2
40
15
0.03
<0.01
<0.03
0.93
<0.01
0.0024
0.40
< 0.002
TREATED EFFLUENT
6.4*
255t
13**
172
4
12.8
3.8
1.0
1.0
0.01
<0.01
<0.03
0.12
0.04
0.003
<0.2
0.025
Value in pH units
'Value in micromhos/cm
»»
Value in cobalt units
576
-------
TABLE VII-54. WASTEWATER COMPOSITION AND TREATED WASTE LOAD
WITH ACID FLOCCULATION AND SETTLING AT MILL 9906
PARAMETER
PH
TDS
TSS
COD
TOC
Oil and Grease
Al
As
Cr
Cu
Total Fe
Total Mn
Hg
Ti
Zn
CONCENTRATION (mg/£)
IN WASTEWATER
7.7*
96
11
14.4
6.8
1.0
2.8
0.01
<0.01
< 0.03
0.25
<0.01
0.0002
<0.2
0.017
TREATED WASTE LOAD „
per unit concentrate produced*
kg/1000 metric tons
-
4.130
473
620
290
43
120
0.43
<0.43
<1.3
11
<0.43
0.009
<8.6
0.73
lb/1000 short tons
_
8,260
946
1,240
580
86
240
0.86
<0.86
<2.6
22
<0.86
0.018
<17.2
1.46
Total amount of ore milled unavailable
Value in pH units
577
-------
TABLE VII-55. WASTEWATER COMPOSITION AND TREATED WASTE LOAD
WITH ACID FLOCCULATION AND SETTLING AT MILL 9907
PARAMETER
PH
IDS
TSS
COD
TOC
Oil and Grease
Al
As
Cr
Cu
Total Fe
Total Mn
Hg
Ti
Zn
CONCENTRATION (mg/fc)
IN WASTEWATER
6.4*
172
4
12.8
3.8
1.0
1.0
0.01
<0.01
<0.03
0.12
0.04
0.0003
<0.2
0.025
TREATED WASTE LOAD
per unit concentrate produced *
kg/1000 metric tons
—
7,050
164
520
150
41
41
0.41
<0.41
<1.2
4.9
1.6
0.01
<0.82
1
lb/1000 short tons
—
14.100
328
1,040
300
82
82
0.82
<0.82
<2.4
9.8
3.2
0.02
0.6
2
Total amount of ore milled unavailable
Value in pH units
578
-------
TABLE VII-56. EFFLUENT CONCENTRATIONS ACHIEVED AT MINES EMPLOYING TREATMENT TECHNOLOGY
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permits, industry monitoring data, and results of analysis
of samples collected by the contractor during site visits.
Treated waste concentrations presented in the tables are
numerical averages, based, in most instances, on the most
recent and most comprehensive monitoring data supplied by
members of the industry. Concentrations for those treated-
waste parameters not monitored at a particular operation
were derived from contractor sample analysis. In addition,
raw-waste concentrations were also derived—primarily, from
contractor sampling data. In all instances, metal parameter
concentrations are total metal values unless specifically
identified otherwise. For those mines and mills where nine
or r.ore data points were available, standard deviations were
calculated as a measure of central tendency. Most annual
production figures for the exemplary facilities are based on
actual 1973 production, although a few figures reflect more
recent production schedules.
The information summarized in these tables provided much of
the data base used for recommending the BPCTCA and BATEA
effluent limitations for those categories not achieving, or
recommended to achieve, zero discharge. These limitations
are identified in Sections IX and X of this document.
580
-------
SECTION VIII
COST, ENERGY, AND NONWATER-QUALITY ASPECTS
INTRODUCTION
The costs of implementation of the best practicable control
technology currently available, the best available
technology economically achievable and new source
performance standards for the ore mining and dressing
industry, as required by Section 304 of the Federal Water
Pollution Control Act Amendments of 1972 (PL92-500), are
summarized in this section; the costs of implementation of
any other Federal, State or local regulations are not
considered.
Included in this section are capital and annual operating
costs which will be incurred by representative operations in
each of the industrial subcategories within the ore mining
and dressing point source category. Also included in this
section where applicable, are the cost of diversion ditching
required for control of runoff specifically for pollution
control. These costs represent incremental costs to attain
specified effluent treatment levels. For example, if the
prevailing current practice encompasses use of tailing
ponds, the capital and operating costs associated with such
ponds are not included. The costs of any additional
treatment facility or activity necessary to meet the pres-
cribed standards, however, are included.
separate capital and annual costs for BPCTCA and BATEA, and
to achieve the New source Performance Standards are
tabulated for typical or representative plants in each
industrial subcategory. Again, these are always expressed
as incremental costs. These costs are then combined in a
summary table to show the total costs incurred to attain the
specified effluent levels. All costs are expressed in 1972
dollars. The Marshall and Stevens Equipment Cost Index for
mining and milling is used where cost adjustments are
required.
A summary of the costing methodology employed is presented
in the section which follows. A detailed description of the
cost categories, factors, relationships, data sources, and
assumptions utilized in computation of the industry costs is
contained in Supplement B. The selected approach entailed
the derivation and validation of costs for the various faci-
581
-------
lities, activities, and materials which, in combination,
form the specified treatment processes.
Where applicable and practical, the costs are developed as a
function of variables which are generally known for specific
facility operations. Supplement B is organized to
facilitate the computation of treatment costs for other
specified plant operations.
SUMMARY OF METHODS USED
Capital Costs
Capital costs include all costs incurred for the
construction, procurement, and installation of required
treatment facilities and equipment.
The major facility and equipment categories used to compute
capital costs are:
Impoundments
Settling Ponds/Lagoons
Tailing Ponds
Tailing-Pond Distribution System
Treatment Processes/Facilities/Equipment
Clari fiers/Thickeners
Lime Neutralization and Precipitation
Hydrated-Lime System
Pebbled-Lime System
Coagulation/Flocculation (including Ferric Sulfate
Treatment)
Sulfide-Precipitation Treatment
Ion Exchange
Aeration
Barium Chloride Coprecipitation
Ammonia Stripping
Recarbonation/Sulfur Dioxide Addition
Transport Systems
Pipes
Pumps
Land
Other Costs
Contingency
Contractor Fee
The cost of impoundment is computed as a function of the
volume contained, total depth, and dike dimensions. Large
562
-------
variations in costs are encountered for the construction of
an impoundment of given size. A major factor is the local
topography. For example, very little dike construction may
be necessary where advantage is taken of an existing ground
depression. In other areas, dikes may have to be
constructed along the entire perimeter. In estimating
impoundment costs for typical plants, it has been assumed
that dikes must be constructed around the entire perimeter.
Detailed data are presented in Supplement B, however, which
permit estimation of costs for specific lagoon and dike
designs. The impoundments have been sized to contain or
treat, as applicable, the estimated runoff from a 1 in 10-
year, 24-hour storm and a 1 in 25-year, 24-hour storm.
It is assumed that cyclones are used at tailing ponds to
separate solids from the waste streams.
Thickener and clarifier costs are based on vendor
quotations. Costs are determined as a function of capacity.
Treatment costs vary with the characteristics and magnitude
of the waste streams. Two types of lime neutralization/pre-
cipitation facilities are considered. One uses hydrated
lime, introduced as a slurry; the other, pebbled lime,
stored dry. The first is practical for operations
characterized by flows of less than 18,925 cubic meters
(5,000,000 gallons) per day. The second is generally used
to treat waste streams of higher volume.
The major components of the hydrated-lime system are tanks,
a slurry mixer and feeder with associated instrumentation,
pumps, and a building to house the latter two components.
Lime storage consists of a 15- to 30-day supply. Treatment
facility costs are computed for application of 0.45 and 0.90
kg of lime per 3,785 liters (1 and 2 lb/1000 gal) of
effluent flow.
The pebbled-lime system consists of storage silo(s), lime
feeders and slakers, mixing tanks, and pumps. Storage silos
are designed to accommodate a 15-day supply of lime. Lime
feeders and slakers with feed. rates of 455 to 1,818 kg
(1,000 to 4,000 Ib) per hour are used, together with mixing
tanks of sufficient size for 15-minute retention. Costs are
developed for treatment systems designed to add 0.9 or 1.4
kg of lime per 3,785 1 (3.785 cubic meters) (equivalent to 2
and 3 lb/1,000 gal) of wastewater.
In some instances, slightly larger applications of lime than
previously noted are necessary where either hydrated- or
583
-------
pebbled-lime facilities are used. No changes in facilities
are made in these cases. Rather, it is assumed that the
lime storage facilities are resupplied more frequently. The
increased application of lime thus is reflected only in
increased operating costs.
Many variations of coagulation and flocculation are
possible. One basic system is considered in this study. It
consists of a mixing tank(s), two holding tanks, and two
positive displacement pumps. The flocculant is mixed to
provide a 0.5-percent solution. The mixture is then
transferred to a holding tank, where the solution is diluted
to 0.1 percent. One of the holding tanks is used to feed
the solution into the waste stream while a new batch of
solution is made up in the other. The pumps are used to
transfer the solution from the mixing tank to the holding
tank and to meter the solution into the waste stream.
Ferric sulfate treatment is essentially similar to
coagulation/ flocculation. A three percent solution is
mixed directly in two holding tanks and metered into the
waste stream. Each tank holds a one-day supply of solution.
The need for the mixing tank and one pump is eliminated.
Coagulation/flocculation and ferric sulfate systems are
tailored to individual plant requirements, as shown in
Supplement B. An important aspect to be noted here is that
there are tradeoffs between equipment sizes and the number
of batches of solution mixed daily.
The cost of installing a sodium sulfide treatment system
generally is very low. in many instances, this system
consists of a 208-liter (55-gallcn) drum, from which the
sulfide solution trickles into the waste stream. The amount
needed depends on the characteristics of the waste stream;
generally, it is of the order of 1 to 2 mg/1 (1 to 2 ppm).
The cost of an ion-exchange unit is a function of the amount
of resin needed, which, in turn, depends on the daily flow,
the characteristics of the wastewater, and the specific
standard to be achieved. The amount of resin required is
determined for each plant where this treatment is employed.
The ion-exchange unit costs include purchase costs of the
main unit, and ancillary equipment, as well as installation
costs.
Two applications of aeration are considered in the study:
one for mixing, the other for oxidation. The former is
56U
-------
designed to raise the DO level in the wastewater. its cost
is determined on the basis of the volume of water to be
agitated. The latter application consists of the chemical
addition of oxygen, where the amount of oxygen required is a
function of chemical change to be achieved. The cost in
this case is computed from the amount of oxygen which must
be added to the water.
Barium chloride coprecipitation treatment costs are based on
industry sources. The original data provided information
for operation rated at a 5,670 m3 (1,500,000 galons) per
day. The cost of reagents are not included as part of the
capital cost. They are included however, under operating
cost.
The main components of a ammonia stripper are a plastic
mixing tank containing caustic soda, a metering pump, and a
packed column. This treatment is used in only one instance.
The amount of wastewater treated is 530 m3 (110,000 gallons)
per day.
Both recarbonation and sulfur dioxide addition utilize a
holding tank sized for five minutes of retention. Carbon
dioxide or sulfur dioxide is bubbled through the wastewater
while it is contained in the holding tank.
Piping and pump requirements depend on the average flow
rates, the characteristics of the waste stream, and the
distance over which the waste stream must be transported.
Pipe and pump sizes and costs for waste streams which
contain a significant amount of solids are based on a flow
rate of 1 m (3.3 ft) per second and on the use of slurry
pumps. Wastewater which carries relatively little solid
material is assumed to be pumped at a rate of 2 m (6.6 ft)
per second utilizing water pumps. The cost of a standby
pump is included in all cases.
All facilities are assumed to be located on rural land. The
cost used is $1,755 per hectare ($730/acre).
Contingency and contractor fees are included as 13 percent
of the capital costs.
Annual Costs
The cost categories included are:
Annual capital recovery
Facility repair and maintenance
585
-------
Equipment repair and maintenance
Operating personnel
Material
Energy (Power)
Taxes
Insurance
Annual capital recovery, as defined for this study, includes
the cost of both capital and the depreciation. The cost of
capital is computed at 8 percent. The assumed useful lives
of facilities and equipment are 20 and 10 years,
respectively.
Annual capital recovery costs are computed as follows.
CA * B (r) (1 + r) exp n
~" ((1 * r) exp n) - 1
where
E = Initial cost
r = True annual interest rate
n = Useful life in years
Annual land cost is also included in the capital recovery
cost. This cost is computed as an opportunity cost at an
annual rate of 10 percent.
Facility repairs and maintenance are included as 3 percent
of initial capital cost, excluding contingency and fee. The
rate applied to equipment is 5 percent of initial installed
cost per year. This is an average cost applicable to mining
and milling equipment.
One exception to the above rates is the maintenance and
repair of tailing ponds. Extensive effort is required for
periodically raising the distribution pipes, moving the
cyclones, and reshaping the upper portions of the dike(s).
The annual cost is estimated at 30 percent of the initial
cost of the distribution system (Reference 7**).
Operating personnel are assigned for specific tasks which
must be performed at the treatment facilities. A cost of
$9.00 per hour, which includes fringe benefits, overhead,
and supervision, is applied-
Material costs are a function of the type of treatment
process employed, the volume of the wastewater which must be
586
-------
treated, its characteristics, and the effluent levels which
must be attained. Representative delivered material costs
are:
Pebbled Lime
Hydrated Lime
Sodium Sulfide
Flocculant
Alum
Ion-Exchange
(IX) Resins
Ferric Sulfate
Barium Chloride
$ 30.80/metric ton
38.50/metric ton
0.22/kg
2.20/kg
0.07/kg
2,500/cubic meter
49.50/metric ton
805.00/metric ton
28.007short ton
35.00/short ton
0.10/lb
1.00/lb
0.03/lb
70.8O/cubic foot
15.00/short ton
730.00/short ton
Energy costs are based on the cost per horsepower-year, com-
puted as follows:
cy
hp
x 0.7457 x hr x Ckw
where
Cy
hp
E
P
hr
Ckw
* Cost per year
= Total horsepower of motors
= Efficiency factor
= power factor
= Annual operating hours
= cost per kilowatt hour
Efficiency and power factors are each assumed to be 0.9; the
cost per kilowatt hour, $0.012.
The computed cost is increased by 10 percent to account for
miscellaneous energy usage.
Annual taxes are computed as 2.5 percent of land
Insurance is estimated at 1 percent of capital cost.
costs.
The discussions which follow are presented by ore mining/
milling category and subcategory. Subcategories in which no
operations currently have discharges are not discussed in
this section.
587
-------
WASTE WATER-TREATMENT COSTS FOR IRON-ORE CATEGORY
Iron-Ore Mines
There are 39 major iron-ore-producing mines currently in
operation. Ore production from these operations ranges from
65,300 to 40,634,000 metric tons (73,000 to 44,800 short
tons) annually, with mine wastewater ranging from 0 to
80,000 cubic meters (0 to 21,000,000 gallons) per day.
A typical mine with an annual ore production of 8,460,000
metric tons (9,400,000 short tons) and a wastewater flow of
47,520 cubic meters (12,500,000 gallons) per day was chosen
to represent this sutcategory.
Two levels of technology are considered. The total cost of
each level is shown in Table VIII-1.
Waste Water Treatment Control
Level A; Coagulation/Flocculation, Settling, and Discharge
The mine wastewater is treated with 25 mg/1 of alum and 1
mg/1 of flocculant for suspended-solid removal. The treated
effluent is then retained for two days in a settling pond
before discharge. The capital and operating costs and
assumptions for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A:
Flocculation system -
1 mixing tank of 1900-liter (500-gallon) capacity
2 holding mix tanks of 9,500-liter (2,500-gallon)
capacity
Piping - Flow aim (3.3 ft)/sec through 60-cm (2-ft) x
250-meter (820-foot) pipe
Pumps - 2 positive-displacement
Pond - 4-meter (13-foot) dike height
6-meter (20-foot) top width
143,000-cubic-meter (37,777,000-gal) capacity
Land - 4.2 hectares (10 acres)
588
-------
TABLE VIII-1. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE
8UBCATEOORY: Iron-Ore Mines
PLANT SIZE: 8,460,000 METRIC TONS (9 .400 .000 SHORT TONS) PER YEAR OF ore
PLANT AGE; ? YEARS PLANT LOCATION; Mesabi Range
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
192 . 5
21.1
88.6
1.3
111.0
0.013
B
384.6
49.7
241.4
15.9
307.0
0.036
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Dissolved Fe
CONCENTRATION
-------
Operating-Cost Assumptions for Level A^
Coagulant - 115.8 metric tons (457.4 short tons)/year
Flocculant - 16.67 metric tons (16.34 short tons)/year
Operating personnel - 5 mixes/day 9 1 hr/mix
Power - 9.7 kW (13 hp)
Capital Investment;
Facilities
Lagoon $ 122,000
Contingency and contractor's fee 15,860
Total facility cost $ 137,860
Land 7,350
Equipment
Flocculation/Coagulation unit 14,900
Piping 27,000
Equipment subtotal 41,900
Contingency and contractor's fee 5,445
Total equipment cost 47,345
Total Capital Investment 192.555
Annual Cost;
Amortization
Facility $ 14,040
Equipment 7,055
Total Amortization $ 21,095
Operation and Maintenance (OSM)
Land $ 735
Operating personnel 15,750
Facility repair and maintenance 3,660
Equipment repair and maintenance 2,095
Materials 64,260
Taxes 185
Insurance 1,925
Total 06M costs $ 88,610
590
-------
Electricity 1.325
Total Annual Cost $ 111.030
Level Bj. Level A plus Lime Precipitation
In addition to level-A technology, the wastewater is treated
with 0.9 kg of pebbled lime per 3.785 cubic meters (2
lb/1000 gallons) of wastewater before entering the settling
pond. Ohe incremental cost for lime precipitation is shown
below.
The capital and operating costs and assumptions for
attaining level B are shown below.
Capital-Cost Components and Assumptions for Level B^
Lime precipitation system
Operating-Cost Assumptions for Level B±
Lime - 4,000 metric tons (1,410 short tons)/year
Operating personnel - 2 hr/shift, 6 hr/day
Power - 108 kW (145 hp)
Capital Investment;
Equipment
Lime precipitation unit S 170,000
Contingency and contractor's fee 22.100
Total equipment cost S 192,100
Total Capital Investment $ 192.100
Annual Cost;
Amortization * 28,630
Operation and Maintenance (OSM)
Operating personnel * 18,900
Equipment repair and maintenance 8,500
Materials 123,480
Insurance 1.920
Total OSM costs 152,800
Electricity 14.570
Total Annual Cost $ 196.000
591
-------
Iron-Ore Mills Employing Chemical and/or Physical Separation
There are 34 iron-ore mills in this subcategory. The amount
of ore milled ranges from 364,000 to 6,600,000 metric tons
(402,000 to 7,236,000 short tons) annually. The daily mill
wastewater ranges from 0 to 22,320 cubic meters (0 to
5,900,000 gallons).
The representative mill operation employing a chemical
and/or physical process mills 5,000,000 metric tons
(5,550,000 short tons) of ore annually. The wastewater flow
is 13,435 cubic meters (3,550,000 gallons) per day.
Two levels of technology are considered for this
subcategory. The total cost of each level is shown in Table
VIII-2.
Waste Water Treatment Conrol
Level A; Flocculation, Settling, and Discharge
The wastewater is treated with 5 mg/1 of flocculant and
flows, by gravity, to a settling pond. The retention time
is assumed to be two days before discharge.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Assumptions for Level Aj,
Pond - 3-meter (10-foot) dike height
6-meter (20-foot) top width
40,300-cubic-meter (10,646,000-gal) capacity
Flocculation system -
1 mixing tank a 1,900-liter (500-gallon) capacity
2 holding tanks 3 9,500-liter (2,500-gallon) capacity
2 positive-displacement pumps
Piping - Flow a 1 meter (3.3 feet)/sec through 32-cm
(1-ft) x 100-meter (328-foot) pipe
Land - 1.6 hectares (4 acres)
592
-------
TABLE VIII-2. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
suBCATEOORYi Iron-Ore Mills Employing Chemical/Physical Separation
PLANT SIZE: 5.000.000 METRIC TONS ( 5 .500 .000 SHORT TONS) PER YEAR OP Ore milled
PLANT AGE: 1 7 YEARS PLANT LOCATION; Michigan ^^^^
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
65.0
7.5
80.1
1.3
88.9
0.018
B
181.0
24.8
139.3
13.3
177.4
0.035
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Dissolved Fe
CONCENTRATION (mg/g,) (ppml
RAW
(UN-
TREATED)
200,000
1.5
AFTER TREATMENT TO LEVEL
A
20
1.0
B
20
0.5
c
0
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: FLOCCULATION, SETTLING, AND DISCHARGE
LEVEL B: LEVEL A PLUS LIME PRECIPITATION
593
-------
Operatinq-Cost Assumptions for Level A_;
Flocculant - 23.45 metric tons (25.8 short tons)/year
Operating personnel - 8 mixes/day 3 1 hour/mix
Power - 9.7 JcW (13 hp)
Capital Investment;
Facilities
Lagoon $ 34,100
Contingency and contractor^ fee 4,435
Total facility cost $ 38,535
Land 2,800
Equipment
Flocculation unit 14,900
Piping 6.100
Equipment subtotal 21,000
Contingency and contractor's fee 2,730
Total equipment cost 23,730
Total Capital Investment $ 65,065
Annual Cost;
Amortization
Facility $ 3,925
Equipment 3,535
Total amortization $ 7,460
Operation and Maintenance (O6M)
Land 280
Operating personnel 25,200
Facility repair and maintenance 1,025
Equipment repair and maintenance 1,050
Materials 51,805
Taxes 70
Insurance 650
Total O6M costs 80,080
Electricity If325
Total Annual Cost $ 88,865
594
-------
Level Bj. Level A plus Lime Precipitation
In addition to level-A technology, the wastewater is treated
with 0.9 kg of hydrated lime per 3.785 cubic meters (2
lb/1000 gal) of wastewater before entering the settling
pond.
The capital and operating costs and assumptions for
attaining this level and this size of operation are shown
below.
Capital-Cost Components and Assumptions for Level B_j_
Lime precipitation system
Operating-Cost Assumptions for Level B;
Lime - 1,127 metric tons (1,240 short tons)/year
Operating personnel - 1 hr/shift, 3 hr/day
Power - 81 kW (108 hp)
Capital Investment;
Equipment
Lime precipitation unit $ 102,650
Contingency and contractor's fee 13,3U5
Total equipment cost $ 115,995
Total Capital Investment I 115,995
Annual Cost;
Amortization
Equipment * 17f285
Total amortization » 17,285
Operation and Maintenance (O6M)
Operating personnel 9,450
Equipment repair and maintenance 5,135
Materials 43,490
Insurance
Total OSM costs
Electricity
Total Annual Cost $
595
-------
WASTE WATER-TREATMENT COSTS FOR COPPER-ORE CATEGORY
Copper Mines
There are 55 major copper-producing mines currently in
operation. Ore production ranges from 130,320 to 34,500,000
metric tons (143,600 to 38,000,000 short tons) annually.
Mine wastewater ranges from 0 to 30,522 cubic meters (0 to
8,064,000 gallons) per day.
A representative copper mine produces 16,550,000 metric tons
(18,250,000 short tons) a year and has an average daily
wastewater flow of 2,725 cubic meters (720,000 gallons).
One level of technology is considered. The total cost for
this level is shown in Table VIII-3.
Waste Water Treatment Control
Level A_: Lime Precipitation. Settling, Re car bonation, and
Discharge
The mine drainage is treated with 0.9 kg of hydrated lime
per 3.785 cubic meters (2 lb/1000 gal) to precipitate
dissolved metals. The treated effluent is then retained in
a settling pond for two days. Recarbonation is required for
pH adjustment before discharge.
The capital and operating cost components and assumptions
for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A:
Pond - 3-meter (10-foot) dike height
3-meter (10-foot) top width
8,500-cubic meter (2,245,000-gal) capacity
Lime precipitation system
Recarbonation system -
1 holding tank, 5-minute retention, 9,500-liter
(2,510-gallon) capacity
1 ejector
Piping - Flow a 2 meters (6.6 feet)/sec through 14-cm
596
-------
TABLE Vlli-3. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE
BUBCATEGORv: Copper Mines
PLANT SIZE: 16.550.000 METRIC TOMS (18 .250 .OOCBHORT TONS> PER YEAR OF ore i»in
PLANT AGE: 19 YEARS PLANT LOCATION: Montana
a. COSTS Of TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER*
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSISI/METRIC TON OF PRODUCT*
COSTS 1*1000) TO ATTAIN LEVEL
A
108.1
15.3
24.0
5.0
44.3
0.003
B
t
t
t
t
t
t
C
D
•MMBMI
•MMM
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
Pb
Hg
Zn
Cu
RAW
(UN
TREATED
40
0.25
0.002
31.3
5.30
CONCENTRATION W£) (ppm)
A
20
0.2
0.001
0.5
0.05
AFTER TREATMENT TO LEVEL
•
20
0.1
0.001
0.5
0.05
C
D
E
ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY OS07
LEVEL A: LIME PRECIPITATION, SETTLING. RECARBONATION. AND DISCHARGE
LEVEL B; LEVEL A * OPERATING EXPERIENCE AND CLOSER CONTROL OF OPERATING
CONDITIONS IN TREATMENT SYSTEM.
f NO ADDITIONAL COSTS INCURRED.
597
-------
(5.5-in.) x 1000-meter (3,280-foot) pipe
Land - 0.54 hectare (1.33 acres)
Operating-Cost Assumptions for Level A_:
Lime - 228.6 metric tons (251.5 short tons) /year
Operating personnel - 1 hr/shift, 3 hr/day
Power - 37 kw (50 hp)
COJ2 - can be reclaimed from milling operations; thus,
no additional cost
Capital Investment;
Facilities
Lagoon $ 12,000
Contingency and contractor's fee 1,560
Total facility cost $ 13,560
Land 975
Equipment
Lime precipitation unit 45,000
Recarbonation 3,800
Piping 34.000
Equipment subtotal 82,800
Contingency and contractor's fee 10,765
Total equipment cost 93,565
Total Capital Investment $ 108.100
Annual Cost;
Amortization
Facility $ 1,380
Equipment 13.945
Total amortization $ 15,325
Operation and Maintenance (OSM)
Land $ 100
Operating personnel 9,450
Facility repair and maintenance 360
598
-------
Equipment repair and maintenance 4,140
Materials 8,820
Taxes 25
Insurance 1,080
Total OSM costs $ 23,975
Electricity 5,000
Total Annual Cost $ 44,300
Copper Mills Using Froth Flotation
There are five mills in this subcategory. Ore production
ranges from 1,211,000 to 17,714,000 metric tons (1,336,000
to 19,530,000 short tons) each year. The daily wastewater
flow ranges from 21,760 to 95,000 cubic meters (5,750,000 to
25,000,000 gallons).
A typical operation that annually mills 8,000,000 metric
tons (8,840,000 short tons) with a daily wastewater flow of
95,000 cubic meters (25,000,000 gallons) was chosen to
represent this sutcategory.
Two levels of technology are considered for this
subcategory. The total cost of each level is shown in Table
VIII-4.
Waste water Treatment Control
Level A:. Lime Precipitation, Polvelectrolvte Addition.
Settling, and Discharge
Approximately 70 percent of the trill effluent is treated
with 1.36 kg of pebbled lime per 3.785 cubic meters (3
lb/1000 gal) of wastewater to precipitate heavy metals from
acid solution. This is later mixed with the remaining
effluent. In addition, polyelectrolytes are added during
upset conditions (spring and summer) to increase
flocculation. The effluent is retained for two days in a
settling pond before discharge. The capital and operating
cost components and assumptions for attaining this level are
shown below.
599
-------
TABLE VIII-4. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
suacATEGORY: Copper Mills Using Froth Flotation
PLANT SIZE: 8,000,000
PLANT AGE; 20 YEARS
METRIC TONS ( 8 ,840 , OOP SHORT TONS) PER YEAR OF Ore milled
PLANT LOCATION: North-Central U.S^
«. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS«)/METRIC TON OF PRODUCT-
COSTS ($1000) TO ATTAIN LEVEL
A
523.7
64.8
342.2
21.5
428.5
0.054
B
1,921.0
286.3
104.2
90.0
480.5
0.06
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cyanide
Pb"
Zn**
Cd***
Cu"
Hg
CONCENTRATION (mg/{.) (ppml
RAW
(UN-
TREATED)
167,000
0.02
0.25
0.58
0.06
2.26
0.0071
AFTER TREATMENT TO LEVEL
A
20
0.015
0.2
0.2
0.05
0.05
0.001
B
0
0
0
0
0
0
0
c
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED). MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION. POLYELECTROLYTE ADDITION, SETTLING. AND DISCHARGE
LEVEL B: TOTAL RECYCLE (ZERO DISCHARGE)
"AVERAGE OF TWO TYPICAL FACILITIES FOR THESE PARAMETERS
••HYPOTHETICAL
600
-------
Capital-Cost Components and Assumptions for Level A*
Pond - 4-meter (13-foot) dike height
6-meter (20-foot) top width
300,000-cubic-meter (79,252,000-gal) capacity
Lime precipitation system
Polyelectrolyte feed system - data supplied from
industry surveys.
Piping - Flow a 2 meters (6.6 feet)/sec through 84-cm
(33-in.) x 100-meter (328-foot) pipe
Land - 11 hectares (27 acres)
Operating-Cost Assumptions for Level A^
»
Lime - 8,100 metric tons (8,910 short tons) /year
Polyelectrolyte - 45.35 metric tons (50 short tons)/year
3 $900/metric ton
Operating personnel - 8 hr/day
Power - 160 kW (215 hp)
Capital Investment;
Facilities
Lagoon $ 194,000
Contingency and contractor's fee 25,220
Total facility cost $ 219,220
Land 19,250
Equipment
Lime precipitation unit $ 230,000
Polyelectrolyte feed system 9,000
Piping 13,400
Equipment subtotal 252,400
Contingency and contractor^ fee 32,810
Total equipment cost 5 285.210
Total Capital Investment $ 523,680
Annual Cost:
Amortization
601
-------
Facility $ 22,330
Equipment 42,505
Total amortization $ 64,835
Operation and Maintenance (O6M)
Land 1,925
Operating personnel 25,200
Facility repair and maintenance 5,820
Equipment repair and maintenance 12,620
Materials 290,900
Taxes 480
Insurance 5.235
Total OSM costs 342,180
Electricity 21.500
Total Annual Cost $ 428,515
Level E:_ Total Recycle (Zero Discharge)
Total recycle includes additional pumps and piping for
recirculating the impounded water from the tailing pond.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level B:
Piping - Flow a 2 meters (6.6 feet)/sec through 84-cm
(33-in.) x 10,000-meter (32,800-foot) pipe
Pumps - 9 75-kW (100-hp) plus 9 standbys
Operating-Cost Assumptions for Level B;
Power - 675 kW (900 hp)
Capital Investment!
Equipment
Piping $1,340,000
Pumps 360*000
Equipment subtotal 1,700,000
Contingency and contractors fee 221,000
Total equipment cost $ 1,921,000
Total Capital Investment SI.921.OOP
Annual Cost:
602
-------
Amortization
Equipment $ 286.290
Total amortization $ 286.290
Operation and Maintenance (OSM)
Equipment repair and maintenance 85,000
Insurance 19,210
Total OCM costs 104,210
Electricity 90,000
Total Annual Cost $480,500
WASTE WATER-TREATMENT COSTS FOR LEAE- AND ZINC-ORE CATEGORY
Lead/Zinc Mines With No Solubility Potential
There are 12 mines in this subcategory. Ore production
ranges from 143,300 to 2,280,000 metric tons (158,000 to
2,514,200 short tons) annually. Mine wastewater flow ranges
from 6,810 to 49,200 cubic meters (1,800,000 to 13,000,000
gallons) per day.
A hypothetical mine was selected as the representative for
this subcategory. It is assumed to have a wastewater flow
of 18,925 cubic meters (5,000,000 gallons) a day and an
annual ore production of 630,000 metric tons (700,000 short
tons).
One level of technology is considered. The total cost of
achieving this level is shown in Table VIII-5.
Waste Water Treatment Control
Level Aj, sedimentation Lagoon, Secondary Settling, and
Discharge
Since there is no solubilization potential for heavy metals,
no precipitation is necessary. However, suspended-solid
concentrations present a problem. The recommended
technology includes use of two settling ponds: one larye
pond with a 10-day retention and a smaller polishing pond
with a 2-day retention.
603
-------
TABLE VI11-5. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
8UBCATEOORY: Lead/Zinc Mines (Mines Exhibiting Low Solubility Potential)
PLANT SIZE; 650,000 METRIC TONS (700,000 SHORT TONS) PER YEAR OF Ore mined
PLANT AGE:N/A YEARS PLANT LOCATION: N/A
.. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSISI/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
413.6
46.7
19.5
8.2
74.4
0.12
B
t
t
t
t
t
t
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cu
Pb
Zn
Hg
CONCENTRATION (mfl/£) Ippcn)
RAW
(UN-
TREATED)
138
0.05
4.9
0.7
0.002
AFTER TREATMENT TO LEVEL
A
20
0.05
0.2
0.5
0.001
B
20
0.05
0.1
0.5
0.001
c
D
E
"ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0507
LEVEL A: SEDIMENTATION LAGOON, SECONDARY SETTLING, AND DISCHARGE
LEVEL B: LEVEL A * OPERATING EXPERIENCE AND CLOSER CONTROL
OF OPERATING CONDITIONS IN TREATMENT SYSTEM
f NO ADDITIONAL COSTS INCURRED
604
-------
Capital and operating cost components and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A£
Pond A - 4-meter (13-foot) dike height
6-meter (20-foot) top width
250,000-cubic-meter (66,043,000-gallon) capacity
Pond B - 3-meter (10-foot) dike height
3-meter (10-foot) top width
50,000-cubic-meter (13,209,000-gal) capacity
Piping - from mine to pond A, 1000 meters (3,280 feet);
from pond A to pond B, 500 meters (1,640 feet).
Flow a 2 meters (6.6 feet)/sec through
37.5-cm (10.8-in.) pipe.
Pumps - from mine to pond A - 1 plus standby,
13,140 1(3,469 gal)/minute each
Operating-Cost Assumptions for Level A;
Power - 60 kW (80 hp)
Capital Investment;
Lagoon(s) $ 225,800
Contingency and contractor's fee 29,355
Total facility cost $ 255,155
Land 19,425
Equipment
Piping 105,000
Pumps 18.000
Equipment subtotal 123,000
Contingency and contractor's fee 15,990
Total equipment cost 138.990
Total Capital Investment $ 413,570
Annual Cost:
Amortization
Facility $ 25,990
Equipment 20,715
605
-------
Total amortization $ 46,705
Operation and Maintenance (OSM)
Land 1,945
Facility repair and maintenance 6,775
Equipment repair and maintenance 6,150
Taxes 485
Insurance 4,135
Total OSM costs 19,490
Electricity 3,165
Total Annual Cost 74,360
Lead/Zinc Mines With Solubility Potential
There are 16 known mines in this subcategory. Annual ore
production ranges from 143,300 to 669,240 metric tons
(158,000 to 737,860 short tons). Mine wastewater flow
ranges from 950 to 131,050 cubic meters (251,000 to
34,623,500 gallons) per day.
A hypothetical mine was selected as representative for this
subcategory. It is assumed to have a wastewater flow of
18,925- cubic meters (5,000,000 gal) per day and an annual
ore production of 630,000 metric tons (700,000, short tons).
Two levels of technology are considered. The total cost of
achieving these levels is shown in Table VIII-6.
Waste Water Treatment Control
Level A:_ Lime Precipitation. Settling, and Didscharqe
Acid mine wastewater has the potential for solubilization of
undesired metals. The technology utilized for this
occurrence is lime precipitation and settling. Since the
mine drainage is acid, a concentration of 1.36 kg of pebbled
lime per 3.785 cubic meters (3 lb/1000 gal) of wastewater is
required to raise pH sufficiently high for precipitating
metals. The treated water is then retained for a minimum of
10 days before discharge. Pumps are not listed as a
separate item, since they are integral parts of the lime
606
-------
TABLE VIII-6. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
SUBCATEGORY: Lead/Zinc Mines (Exhibiting High Metals Solubility)
PLANT SIZE: 630,000 METRIC TONS I _700_J.QQD SHORT TONS) PER VEAR OFOre mined
PLANT AGE: N/A YEARS PLANT LOCATION: N/A
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSISI/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
407.3
49.1
115.5
10.9
175.5
0.28
B
671.5
88.5
129.8
11.9
230.2
0.37
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cu
Pb
Zn
Hg
CONCENTRATION (mo/£) (ppm)
RAW
(UN-
TREATED*
58
0.06
0.3
38.0
0.005
AFTER TREATMENT TO LEVEL
A
20
0.05
0.2
0.5
0.001
B
20
0.05
0.1
0.5
0.001
c
D
E
*ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION. SETTLING, AND DISCHARGE
LEVEL B: LEVEL A + OPERATING EXPERIENCE AND CLOSER CONTROL
OF OPERATING CONDITIONS IN TREATMENT SYSTEM
607
-------
precipitation unit. Capital and operating cost components
and assumptions for attaining this level are shown below.
Pond - 4-meter (13-foot) dike height 6-meter (20-foot)
top width 250,000-cubic-meter (66,043,000-gal)
capacity
Land - 9 hectares (22 acres)
Lime precipitation system
Piping - Flow a 2 meters (6.6 feet)/sec through 37.5-cm
(14.8-in.) x 1000-meter (3,280-foot) pipe
Operating-Cost Assumptions for Level A_:
Lime - 2,380 metric tons (2,625 short tons)/year
Operating personnel - 2 hr/shift, 6 hr/day
Power - 80 kW (107 hp)
Capital Investment
Facilities
Lagoon $ 174.000
Contingency and contractor's fee 22.620
Total facility cost $ 196,620
Land 15,750
Equipment
Lime precipitation unit 102,500
Piping 70.000
Equipment subtotal 172,500
Contingency and contractor's fee 22.425
Total equipment cost 194.925
Total Capital Investment $ 407,295
Annual Cost;
Amortization
Facility $ 20,025
608
-------
Equipment 29,050
Total amortization $ 49,075
Operation and Maintenance (OSM)
Land $ 1,575
Operating personnel 18,900
Facility repair and maintenance 5,220
Equipment repair and maintenance 8,625
Materials 73,500
Taxes 3,625
Insurance 4,070
Total OSM costs $
Electricity
Total Annual Cost $
Level B^ High-Density sludge Process
In addition to lime and settling as described for level A, a
high-density sludge process has been suggested for enhanced
removal of dissolved metals.
This process has been costed as a separate item. The incre-
mental cost for implementing this system is shown below.
The total cost for this system must be added to level-A
costs, since lagoons and lime precipitation are necessary
for the operation of this technology. Capital and operating
cost components and assumptions for attaining this level are
shown below.
Capital-Cost Components and Assumptions for Level B:^
Clarifier - 8-hr retention, 6,350-cubic-meter (1,680,000-gal)
capacity.
Underflow from clarifier is 10X of inflow, and
50% of underflow is discharged to settling pond
with overflow; thus, 5X of underflow is recir-
culated through lime precipitation unit.
Slurry Pump - 660 liters (17U gal)/minute
Pipe - Flow a 1 meter (3.3 ft)/sec through 12.5-cm
(4.9-in.) x 50-meter (164-foot) pipe from clarifier
to precipitation unit.
Operating-Cost Assumptions for Level I3£
609
-------
Power - 7.5 kW (10 hp)
Capital Investment;
Equipment
Clarifier $ 226,800
Piping 1,500
Pumps 5,500
Equipment subtotal 233,800
Contingency and contractors fee 30,395
Total equipment cost $ 264,195
Annual Cost;
Amortization
Equipment 39,375
Total amortization 39,375
Operation and Maintenance (O&M)
Equipment repair and maintenance 11,690
Insurance 2,640
Total O&M costs 14,330
Electricity 1,000
Total Annual Cost $ 54,705
Lead/Zinc Mills
There are 21 known major lead/zinc mills in operation. The
amount of ore milled by these operations ranges from 195,840
to 2,520,000 metric tons (215,920 to 2,778,390 short tons)
annually. The daily mill wastewater flow ranges from 0 to
15,120 cubic meters (0 to 4,000,000 gallons).
A hypothetical mill was selected as representative for this
subcategory. It is assumed to have an annual milling
capacity of 630,000 metric tons (700,000 shor tons), with a
daily wastewater flow rate of 5,678 cubic meters (1,500,000
gallons) .
610
-------
Two alternative levels of technology are considered for this
subcategory. The total cost of each level is shown in Table
VIII-7.
Waste Water Treatment/Control
The best practiced technology consists of use of a tailing
pond, followed by a secondary settling pond. A. minimum 10-
day retention time in the tailing pond and a 2-day retention
time in the secondary settling pond are recommended. The
tailing distribution system consists of piping, around the
perimeter of the tailing pond, and cyclones, located at 100-
meter (328-foot) intervals along one length of the tailing
dam.
Capital and operating cost components and assumptions for
attaining level A are shown below.
Capital-Cost Components and Assumptions for Level A:.
Tailing pond - 3-meter (10-foot) dike height
3-meter (10-foot) top width
4,245-meter (13,925-ft) perimeter
Settling Pond - 3-meter (10-foot) dike height
3-meter (10-foot) top width
15,000-cubic-meter (3,963,000-gal) capacity
Land - 101 hectares (250 acres)
Distribution system - 4,245 meters (13,924 feet) of
(7.9-in.) pipe
12 cyclones 3 $1,800 each
Piping - Flow at 1 meter/sec through 30-cm (1-ft) pipe:
from mill to tailing pond, 1000 meters (3,280 ft);
from tailing pond to lagoon, 500 meters (1,640 ft)
Slurry pumps - 1 plus standby, 3,900 1 (1,042-gal)/minute
Operating- cost Assumptions for Level A:.
Tailing-pond distribution system maintenance i 30* of
distribution cost
Power - 18.6 kW (25 hp)
611
-------
TABLE VIII-7. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGORY
. Lead/Zinc Mills
PLANT SIZE: 630,000
PLANT AG£:N/A YEARS
_ METRIC TONS (700,000 SHORT TONS) PER YEAR QF Ore milled
PLANT LOCATION: N/A
m. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
1,117.0
116.6
124.7
2.5
243.8
0.38
B
1,199.0
128.8
129.1
6.5
264.4
0.42
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cyanide
Cd**
Cu
Hg
Pb
Zn
CONCENTRATION (me/ 2,1 (ppm)
RAW
(UN-
TREATED)
350,000
0.03
0.055
0.36
0.015
1.9
0.46
AFTER TREATMENT TO LEVEL
A
20
0.01
0.05
0.05
0.001
0.2
0.2
B
0
0
0
0
0
0
0
c
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: TAILING POND, SECONDARY SETTLING. AND DISCHARGE
LEVEL B: TOTAL RECYCLE (ZERO DISCHARGE)
•HYPOTHETICAL
612
-------
Capital Investment;
Facilities
Tailing pond $ 420,255
Lagoon 19,940
Facility subtotal 440,195
contingency and contractorfs fee 57,225
Total facility cost $ 497,420
Land 176,750
Equipment
Distribution system 284,790
Piping 93,000
Pumps 14.000
Equipment subtotal 391,790
Contingency and contractor's fee 50.935
Total equipment cost 442,725
Total Capital Investment $ 1.116.895
Annual Cost;
Amortization
Facility $ 50,665
Equipment 65.980
Total amortization $ 116,645
Operation and Maintenance (O6M)
Land $ 17,675
Facility repair and maintenance 600
Equipment repair and maintenance 5,350
Tailing pond and distribution maintenance 85,435
Taxes 4,420
Insurance 11.170
Total OSM costs $ 124,650
Electricity
Total Annual Cost $ 243,795
Level BI Total Recycle (Zero Discharge)
Total recycle can be attained only after impoundment systems
as described for level A have been constructed. Thus, the
costs cited for level B are the incremental costs for imple-
613
-------
men-ting total recycle. The equipment includes decant pumps
and piping. Costs for implementing total recycle are shown
in Table VIII-7.
Capital-Cost Components and Assumptions for Level B
Decant Pumps - water pumps - 3,900 1 (1,042 gal)/minute,
1 plus standby
Piping - Flow 3 2 meters (3.3 feet)/sec through 21-cm
(8.3-in.) pipe, 1,500 meters (4,920 feet) long
Operating-Cost Assumptions for Level B:.
Power - 30 kw (10 hp)
Capital Investment;
Equipment
Piping $ 64,500
Pumps 8,000
Equipment subtotal 72,500
Contingency and contractor's fee 9,425
Total equipment cost $ 81,925
Annual Cost;
Amortization
Equipment 12.210
Total amortization 12,210
Operation and Maintenance (O&M)
Equipment repair and maintenance 3,625
Insurance
Total OGM costs
Electricity 4,000
Total Annual Cost $ 20,655
WASTE WATEB TREATMENT COSTS FOR GOLD ORE CATEGORY
Gold Mines (Alone)
614
-------
Three known mines operating alone without discharge to mill
treatment facilities exist in this subcategoryr only two of
which are discharging. The range of ore mined is 163,000 to
478,000 metric tons (180,000 to 527,000 short tons)
annually. The average daily discharge for these operations
is 3,785 cubic meters (1,000,000 gallons).
A hypothetical mine with an annual ore production of 320,000
metric tons (353,000 short tons) and with a discharge of
3,785 cubic meters (lrOOO,000 gallons) per day was chosen to
represent this subcategory.
Two levels of technology are considered. The incremental
costs for the representative gold mine to attain levels A
and B are shown in Table VIII-8.
Wa ste Water Treatment/Control
Level A£ Sedimentation (Settling Pond)
Level A consists of a sedimentation pond with a one-day
retention. It is assumed that mine dewatering pumps already
have been installed.
The capital and operating costs and assumptions for attain-
ing this level are shown below.
Capital-Cost Components and Assumptions for Level A:,
Sedimentation pond - dike height of 3m (10 ft)
top width of 3 m (10 ft)
capacity of 5,700 cubic meters
(1,506,000 gal)
Piping - Flow 3 2 meters/sec (6.6 feet) through pipe
measuring 17 cm (6.7 in.) x 1000 meters
(3,300 feet)
Capital Investment;
Facilities
Lagoon $ 9,000
Contingency and contractor's fee 1,170
Total facility cost $ 10,170
700
615
-------
TABLE VIII-8. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
. Gold Mines (Alone)
8UBCATEQORY:
PLANT SIZE: 320,000 METRIC TOMS<353»000 SHORT TONS! PER YEAR OF Ore mined
PLANT ACE;N/A YEARS PLANT LOCATION: N/A
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER!
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
53.8
7.4
2.3
9.7
0.03
B
121.2
17.3
28.1
4.4
49.8
0.16
c
t
t
t
t
t
t
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cu
Hg
Zn
Pb
CONCENTRATION (mg/£) (ppm)
RAW
(UN-
TREATED)
25
0.06
0.002
6
0.3
AFTER TREATMENT TO LEVEL
A
20
0.06
0.002
4
0.25
B
20
0.05
0.001
0.5
0.2
c
20
0.05
0.001
0.5
0.1
D
E
ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.807
LEVEL A: SEDIMENTATION (SETTLING POND)
LEVEL B: SEDIMENTATION. LIME PRECIPITATION, SECONDARY SETTLING. AND DISCHARGE
LEVEL C: LEVEL B + OPERATING EXPERIENCE AND CLOSER CONTROL
OF OPERATING CONDITIONS IN TREATMENT SYSTEM
t NO ADDITIONAL COST INCURRED
616
-------
Piping 38,000
Contingency and contractor's fee 4,940
Total equipment cost 42,940
Total Capital Investment S 53,810
Annual Cost;
Amortization
Facility $ 1,035
Equipment 6,400
Total amortization $ 7,435
Operation and Maintenance (O6M)
Land
Facility repair and maintenance
Equipment repair and maintenance
Taxes
Insurance
Total OSM costs
Total Annual Cost $ 9r750
Level B; sedimentation. Lime Precipitation. Secondary Settling.
and Discharge
Level-B technology utilizes a sedimentation pond with a
retention time of one day and a smaller settling pond with a
6-hour retention period. The mine water has a pH of 6;
thus, addition of 0.9 kg of hydrated lime per 3.785 cubic
meters (2 lb/1,000 gal) of water would raise the pH
sufficiently for precipitation of metals.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost components and Assumptions for Level B:
Sedimentation pond - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity of 5,700 cubic meters
(1,506,000 gal)
Settling pond - dike height of 4 m (13 ft)
top width of 3 m (10 ft)
617
-------
capacity of 1,425 cubic meters (376,000 gal)
Land - 0.5 hectare (1.24 acres)
Lime precipitation system
Piping - Flow a 2 meters (6.6 feet)/sec through pipe measuring
17 cm (6.7 in.) x 1,100 meters (3,600 feet)
Operating-Cost Assumptions for Level B:
Lime - 317 metric tons (350 short tons)/year
Operating Personnel - 1 hr/shift, 3 hr/day
Power - 30 kw (HO hp)
Capital Investment:
Facilities
Lagoon(s) $ 12,275
Facility subtotal 12,275
Contingency and contractor's fee 1,595
Total facility cost $ 13,870
Land 875
Equipment
Lime precipitation unit 54,400
Piping 41,800
Equipment subtotal 94,200
Contingency and contractor's fee 12,245
Total equipment cost 106,445
Total Capital Investment $ 121,190
Annual cost:
Amortization
Facility $ 1,415
Equipment 15,865
Total amortization $ 17,280
Operations and Maintenance (OSM)
Land 90
618
-------
Operating personnel 9,450
Facility repair and maintenance '370
Equipment repair and maintenance 4,710
Materials 12,250
Taxes 20
Insurance 1,210
Total O&M Costs $ 28,100
Electricity (4,400
Total Annual Cost $ 49,780
Gold Mills or Mine/Mills (Cyanidation Process)
In 1974 there were three known mills practicing cyanidation,
with one of these operations employing both flotation and
cyanidation. During late 1975 and 1976, a number (3-6) of
additional operations began full scale production. These
operations are predominately located in Nevada and attain
zero discharge by virtue of impoundment and recycle. The
range of ore milled in this subcategory is 476,000 to
1,400,000 metric tons (527,000 to 1,550,000 short tons) per
year. The wastewater flow ranges from 490 to 29,900 cubic
meters (130,000 to 7,900,000 gallons) per day.
The representative mill has an annual production of
1,400,000 metric tons (1,550,000 short tons) and a daily
wastewater flow of 29,900 cubic meters (7,900,000 gallons).
Two levels of technology are considered. The incremental
costs of achieving these levels are shown in Table VIII-9.
Wastewater Treatment/Control
Level AJ. Recycle
Recycle for this subcategory entails use of an impoundment
system, thickeners, piping and pumps. The mine water is
collected in the mill reservoir and used as makeup water in
the mill cyanide leaching processes. Approximately 3,800
cubic meters (1,000,000 gallons) of wastewater are dischared
daily (volume approximately equivalent to net mine water
flow). The treatment of this flow is considered in
Treatment Level B.
The capital and operating costs and major assumptions for
attaining Level A are shown below.
619
-------
TABLE ?I!T-9 WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
suacATEGORY: Gold Mills or Mine/Mills (Cyanidation Process)
PLANT SIZE: 1,400,000 METRIC TONS (1. 550, OOP SHORT TONSI PER YEAR OF Ore Milled
PLANT AGE:100 YEARS PLANT LOCATION: South Dakota
». COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
r>OTAi. INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
8,017
849.1
723.2
85.7
1,658.0
$1.18
B
8,309
892.6
776.8
90.7
1,760.1
$1.26
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cyanide
Cu
HE
Zn
CONCENTRATION lmg/1) (ppm)
RAW
(UN-
TREATED)
500,000
1.0
2.9
0.006
0.34
AFTER TREATMENT TO LEVEL
A
0
0
0
0
0
Bt
0
0
0
0
0
c
D
E
TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: RECYCLE
LEVELS: RECYCLE (WITH OZONATIONI
^COMBINED WASTEWATER DISCHARGE EQUIVALENT TO MINEWATER FLOW IS EXPECTEDTO EMPLOY
OZONATION PLUS CARBON ABSORPTION AND YIELD THE FOLLOWING WATER QUALITY LEVELS:
TSS < 10 mg/l; CN < 0.02 mg/l;Cu < 0.05 mg/l; Hg f 0.0001 mg/l,Zn -4 0.3 mg/l
620
-------
Capital-Cost Components and Assumptions for Level A^
Tailings pond dike - dike height of 75 m (250 ft)
- top width of 10 m (30 ft)
- dike length 120 m (395 ft)
Diversion ditching - 7,400 m (24, 270 ft)
Land - 221 ha (547 acres)
Piping - 9,600 m (31,490 ft) of 60 cm (24 inch) pipe
Pumps - 8 - 100 hp slurry pumps and 2 - 20 hp water pumps
Operatincr-Cost Assumptions for Level A;
Power - 626 kW (840 hp)
Personnel - 116 manhours/day
Capital Investment:
Facilities
Tailings pond dike $4,920,000
Diversion ditching 511,000
Facility subtotal 5,431,000
Contingency and contractor's fee 706.000
Total facility cost $6,137,000
Land 383,000
Equipment
Piping $1,056,000
Pumps 269.000
Equipment subtotal 1,325,000
Contingency and contractor's fee 172.000
Total equipment cost $1,497,000
Total Capital Investment $8.017.000
Annual Cost;
Amortization
621
-------
Facilities $ 626,000
Equipment 223.100
Total amortization $ 849,100
Operation and Maintenance (OSM)
Land $ 38,300
Operating personnel 365,900
Facility repair and maintenance 162,900
Equipment repair and maintenance 66,300
Taxes 9,600
Insurance 80.200
Total O&M Costs $ 723,200
Electricity 85.700
Total Annual Cost $1.658.000
Level B: Recycle with Ozonation of Mill Water Discharge
Level B is the same as Level A with the addition of an
ozonation system to reduce the cyanide concentration in the
mill water discharge.
Capital-Cost Components and Assumptions for Level B
Ozone requirement - 18 leg (40 Ib) per day
Piping - 200 m (650 ft) of 20 cm (8 inch) pipe
Pump - 1 - 20 hp water pump
Annual-Cost Assumptions for Level B;
Power - 36.5 kW (49 hp)
Personnel - 12 manhours/day
Capital Investment;
Ecruipment
Ozonation system $ 243,000
Piping 9,000
Pump 6.000
Equipment subtotal 258,000
Contingency and contractors fee 34,000
622
-------
Total Capital Investment $ 292 000
Annual Cost:
Amortization $ 43,500
Operation and Maintenance
Operating personnel 37,800
Equipment repair and maintenance 12,900
Insurance 2.900
Total O6M costs 53,600
Electricity
Total Annual Cost $ 102.100
Gold Mills (Amalgamation Process)
One known mill utilizes the process of amalgamation. it
mills 163,000 metric tons (180,000 short tons) yearly and
discharges 2,271 cubic meters (600,000 gallons) of
wastewater daily. Three levels of technology are
considered. The total costs of achieving these levels are
shown in Table VIII-10.
Waste Water Treatment Control
Level A:. Lime Precipitation, and Discharge
The typical mill in this subcategory has adequate
impoundment systems for sedimentation purposes. To achieve
level A, lime precipitation would be necessary. The
addition of 0.9 kg of hydrated lime per 3.785 cubic meters
(2 lb/1000 gal.) is recommended for achieving level A.
The capital and operating costs assumptions for attaining
this level are given below.
Capital-Cost Components and Assumptions for Level A
Lime precipitation system - hydrated lime, stored as a
slurry.
Operating-Cost Assumptions for Level A
Lime - 190 metric tons (210 short tons)/year
623
-------
TABLE VIII-10. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGORY: Gold Mills (Amalgamation Process)
PLANT SIZE: 163.000 METRIC TONS ( 180.000 SHORT TONSI PER YEAR OF Ore milled
PLANT AGE: 45 YEARS PLANT LOCATION: Colorado
». COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
45.2
6.7
19.3
2.0
28.0
0.17
B
45.3
6.7
22.7
2.0
31.4
0.19
c
213.5
31.8
12.8
44.6
0.27
D
41.5
6.2
1.9
1.5
9.6
0.06
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cu
Hg
Zn
CONCENTRATION (mg/£) (ppm)
RAW
(UN-
TREATED)
250,000
0.6
0.002
1.3
AFTER TREATMENT TO LEVEL
A
20
0.05
0.0004
0.2
B
20
0.05
0.0001
0.2
c
20
0.05
<0.0001
0.2
D
0
0
0
0
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION AND DISCHARGE
LEVEL B: LEVEL A PLUS SULFIDE PRECIPITATION
LEVEL C: PROCESS CHANGE FROM AMALGAMATION TOCYANIDATION
LEVEL D: TOTAL RECYCLE (ZERO DISCHARGE)
624
-------
Operating personnel 1 hr/shift, 3 hr/day
Power - 20 HP
Capital Investment
Equipment
Lime precipitation system $ 40,000
Contingency and contractor's fee 5,200
Total Equipment Cost $ 45,200
Total Capital Investment $ 45,200
Annual Cost;
Amortization $ 6,720
Operation and Maintenance (O6M)
Operating Personnel $ 9,450
Equipment repair 6 maintenance 2,000
Materials 7,350
Insurance 450
Total OSM Costs 19,250
Electricity 2.000
Total Annual Cost $ 27.970
Level B_^ Level A, Sulfide Precipitation and Discharge
Level B requires the addition of 1.5 mg/1 of sodium sulfide
to the wastewater stream. Costs for sulfide precipitation
are shown below. Total Level B costs are shown in Table
Vlli-io.
Capital-Cost Components and Assumptions for Level B
Sodium sulfide distribution system
Operatinq-Cost Assumptions for Level B
Sodium sulfide 1,192 kg (2,627 Ib)/year
Operating personnel 1 hr/day
Capital Investment;
625
-------
Equipment
Sulfide precipitation unit
Contingency and contractors fee
Total Equipment Cost
Amortization $ 15
Operation and Maintenance (OGM)
Operation personnel $ 3r150
Equipment repair 6 maintenance 5
Materials 210
Total O6M Costs $ 3,365
Total Annual Cost $ 3,380
Level C; Process Change from Amalgamation to Cyanidation
An alternative to precipitation for this subcategory would
be to change the milling process from amalgamation to
cyanidation. The costs incurred for this process change are
difficult to obtain and estimate. However, data were
provided for a similar change for an operation whose mill-
circuit volume is 10 times greater than the one in this
subcategory. To estimate the cost for the process change,
an application of the six-tenths-factor rule was used.
Note that a mill with a water flow of 22,710 cubic meters
(6,000,000 gal)/day incurred a capital investment cost of
$850,000 for the process change. Applying the six-tenths-
factor rule to an operation whose water flow is 2,271 cubic
meters (600,000 gal)/day resulted in a capital investment
cost of $213,510. No assumptions were made as the the
amounts of materials, operating labor, and power that would
be required, as these data are not available. Equipment
repair and maintenance were assumed to total 5 percent of
capital investment. Amortization was assumed over a 10-year
period. The costs are shown in Table Vlll-10.
The capital and operating costs for attaining this level are
shown below.
Capital Investment;
Equipment
626
-------
Process change $ 213,510
Annual Cost;
Amortization $ 31,820
Operation and Maintenance (O6M)
Equipment repair and maintenance $ 10,675
Insurance 2,135
Total O6M costs 12,810
Total Annual Cost $ 44,630
Level D± Total Recycle (Zero Discharge)
To achieve total recycle, additional pumps and piping would
be necessary to recirculate the wastewater. The capital and
operating cost components and assumptions for attaining this
level are shown below.
Capital-Cost Components and Assumptions for Level Cj_
Piping - Flow 3 2 meters (6.6 feet)/second through pipe
measuring 13 cm (5.1 in.) x 1000 meters (3,300 feet)
Pumps - water pumps with capacity of 15.77 cubic meters
(4,166 gal)/minute
Operating-Cost Assumptions for Level C:
Power - 11.2 kW (15 hp)
Capital Investment;
Equipment
Piping $ 32,000
Pumps 4,700
Equipment subtotal 36,700
Contingency and contractor^ fee 4,770
Total Capital Investment $ 41,470
Annual Cost;
Amortization $ 6,170
627
-------
Operation and Maintenance (OSM)
Equipment repair and maintenance $ 1,835
Insurance 40
Total OSM costs 1,875
Electricity 1,500
Total Annual Cost $ 9,545
Geld Mills (Flotation)
The one mill which exists in this sufccategory processes
50,000 metric tons (55,000 short tons) of ore annually. The
flow from the mill is 190 cubic meters (130,000 gallons) per
day. A discharge from the tailing pond occurs for only two
months of the year and amounts to 545 cubic meters (144,000
gallons) per day.
Two alternative treatment levels are considered. The costs
of achieving these levels are shown in Table VIII-11.
Waste Water Treatment Control
Level A; Diversion Ditching, Lime Precipitation, and
Alkaline Chlorination
Adequate impoundment systems exist for the mill in this sub-
category. Lime precipitation is recommended for the
precipitation of metals. The recommended dosage is 0.9 kg
of hydrated lime per 3.785 cubic meters (2 lb/1000 gal) of
wastewater. Control is also needed to divert seasonal
runoff that results in tailing-pond overflow.
Cyanide is used in the flotation process. Should an
accidental discharge occur, Chlorination of the cyanide
solution would be necessary. The amount of chlorine needed
would depend upon the amount of cyanide in the wastewater.
Since discharge of cyanide is not a typical occurence, no
estimate of the amount of chlorine has been made.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Levej. Aj^
Diversion ditching - total of 1000 meters (3,280 feet)
628
-------
TABLE VIIM1. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGORY: Gold Mills (Flotation")
PLANT SIZE; 50,000
PLANT AGE: 39 YEARS
^METRIC TONS ( ^55.000 SHORT TONS) PER YEAR OF Ore milled
PLANT LOCATION: Washington
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS IS1000I TO ATTAIN LEVEL
A
20.3
3.5
12.1
1.0
16.6
0.33
a
31.2
4.5
12.6
1.0
18.1
0.36
c
D
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cyanide
*'
Cu
Zn
Cd f
Pb'
CONCENTRATION (mg/i) (ppm)
RAW
(UN-
TREATED)
240,000
109
0.005
10.8
79
0.10
0.40
AFTER TREATMENT TO LEVEL
A
20
o.ni
0.001
0.05
0.2
0.05
0.2
a
0
0
0
0
0
0
0
c
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED). MULTIPLY COSTS SHOWN BY 0.907
f HYPOTHETICAL • BASED ON OPERATIONS VISITED IN SUBCATEGORY
LEVEL A: DIVERSION DITCHING, LIME PRECIPITATION. AND ALKALINE CHLORINATION
LEVEL B: LEVEL A PLUS SETTLING POND - NO DISCHARGE
629
-------
Alkaline chlorinator - V-notch type; data supplied from
surveyed operation
Lime precipitation - 15-day supply of lime slurry.
Mix tank with capacity of 7.4 cubic
meters (Ir955 gal) for slurry storage.
Mix tank with capacity of 5.2-cubic
meters (1,374 gal) for 15-minute
retention.
Slurry pump - 0.34 cubic meter (90 gal)/minute
Operating-Cost Assumptions for Level A^
Lime - 41 metric tons (46 short tons)/year
Operating personnel - 3 hr/day
Power - 7.5 kW (10 hp)
Capital Investment;
Facilities
Diversion ditching S 1,650
Contingency and contractor's fee 215
Total facility cost $ 1,875
Equipment
Lime precipitation unit 6,400
Aklaline chlorinator 5,660
Pumps 4,200
Equipment subtotal 16,260
Contingency and contractor's fee 2,115
Total equipment cost 18,375
Total Capital Investment S 20,250
Annual Cost;
Amortization
Facility 190
Equipment 3,505
Total amortization $ 3,505
Operation and Maintenance (OSM)
630
-------
Opera-ting personnel 9,450
Facility repair and maintenance 50
Equipment repair and maintenance 815
Materials 1,610
Insurance 200
Total OSM costs 12,125
Electricity 1,000
Total Annual Cost $ 16,630
Level E5j!_ Level A plus Settling Pond - No Discharge
To avoid discharge of the seasonal runoff, an additional
settling pond will be necessary. The runoff would be
collected in the settling pond and stored for use as mill
process water. A five-day retention time is assumed.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level B^
Pond - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity of 5,700 cubic meters (1,506,000 gal)
Land - 0.4 hectare (1 acre)
Capital Investment;
Facilities
Lagoon S 9,000
Contingency and contractor's fee 1*170
Total facility cost f 10,170
Total Capital Investment $ 10.870
Annual Cost;
Amortization $ 1,035
Operation and Maintenance (O&M)
Land $ 70
631
-------
Facility repair and maintenance 270
Taxes 20
Insurance 110
Total OSM costs 470
Total Annual Cost $ 1,505
Gold Mine/Mi11s Employing Gravity Separation
There are approximately 200 known placer operations at
present. The Bureau of Mines estimated that, at the 68
operations known in 1972, the amount of material washed
totaled 698,145 cubic meters (913,000 cutic yards) per year
(Reference 2). Assuming that the material moved on the
average by the industry is proportional from year to year, a
conservative estimate of 2,054,000 cubic meters (2,690,000
cubic yards) can be obtained. The wastewater flow is 11,355
to 15,140 cubic meters (3,000,000 to 4,000,000 gallons) per
day. The placer mining industry, for the most part, is
located in Alaska. The mining season there lasts for
approximately 100 to 120 days, depending upon location. It
has been reported by some members of the industry that, in
surface-stripping operations, 765 cubic meters (1,000 cubic
yards) of material can be moved in an eight-hour day. Both
the length of the mining season and the amount of material
moved can be significantly modified due to "down time"
caused by mechanical failure or poor weather.
A hypothetical operation based on an arithmetric average of
68 operations from Reference 2, was selected as
representative for this subcategory. The annual material
handled for the representative operation is 10,270 cubic
meters (13,425 cubic yards). Assuming a specific gravity of
2.65 for this material, the total weight handled is 27,215
metric tons (30,000 short tons) each year. This estimate
does not include overburden but rather ore washed. The
assumed daily water flow is 13,247 cubic meters (3,500,000
gallons) .
Four alternative levels of technology are considered.
The capital and operating costs of achieving these levels
are shown in Table VIII-12.
Waste Water Treatment/Control
Level A: Settling Pond
632
-------
TABLE VII1-12. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL
MINE/MILL
SUBCATEOORY: Gold Mine/Mills Employing Gravity Separation
PLANT SIZE: 27,215 METRIC TONS i 30,000 SHORT TONS) PER YEAR OF Ore milled
PLANT AGE:N/A YEARS PLANT LOCATION: N/A
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS (SI/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
12.9
1.2
0.6
1.8
0.066
B
34.4
5.1
9.5
4.0
18.6
0.68
c
47.3
6.3
10.1
4.0
20.4
0.75
D
57.5
7.8
40.5
4.1
52.4
1.93
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
Settleable Solids
RAW
(UN-
TREATED
3-200
CONCENTRATION (mJl/t)
AFTER TREATMENT TO LEVEL
A
0.5
B
0.5
c
<0.5
0
<0.5
E
OR* MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN «Y OJV?
LEVEL A: SETTLING POND
LEVEL B: DISTRIBUTION SYSTEM
LEVEL C; SETTLING POND AND DISTRIBUTION SYSTEM
LEVEL D: SETTLING POND, DISTRIBUTION SYSTEM, AND FLOCCULATION
633
-------
The recommended treatment system for level A consists of a
settling pond for removal of suspended solids. The capital
and operating costs and assumptions for attaining this level
are shown below.
Capital-Cost components and Assumptions for Level A^
Settling pond - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity of 7,380 cubic meters (1,950,000 gal)
Land - O.U hectare (1 acre)
Capital Investment;
Facilities
Lagoon $ 10,800
Contingency and contractor's fee 1,405
Total facility cost $ 12,205
Land 700
Total Capital Investment $ 12,905
Annual Cost:
Amortization $ 1,245
Operation and Maintenance
Land 70
Facility repair and maintenance 325
Taxes 20
Insurance 3.30
Total OSM costs 5U5
Total Annual Cost $ 1,790
Level B; Distribution System
An alternative to level-A treatment would be to construct
and utilize a process-water distribution system. The
purpose would be to deliver dredge wastewater to all mine
workings for filtration. The capital and operating costs
and assumptions for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level B:
634
-------
Piping - Flow 31m (3.3 ft)/sec through pipe measuring
45 cm (17.7 in.) x 100 meters (330 feet)
Pumps - slurry type (plus one standby)
Ope rat ing-Cost Assumptions for Levej. B;
Power - 30 Jew (HO hp)
Distribution system maintenance 9 30% of system
capital cost
Capital Investment;
Equipment
Piping $ 8,40,0
Pumps 22,000
Equipment subtotal 30,400
Contingency and contractor's fee 3,950
Total Capital Investment S 34,350
Annual Cost;
Amortization $ 5,120
Operation and Maintenance (05M)
Distribution system maintenance $ 9,120
Insurance 345
Total OCM costs
Electricity
Total Annual Cost $ 18,585
Level Cj. Settling Pond and Distribution System
Level c is the sum of levels A and B. Total invested
capital and annual operating costs for this level are shown
in Table VIII-12.
Level D:. settling Pond, Distribution System, and
FlocculatTon
635
-------
Level D is the same as level C plus the addition of a
flocculant for further suspended-solid removal. It is
assumed that 2 mg/1 of flocculant is added. A simple
flocculant feed system is all that is needed. The
incremental capital and operating costs and assumptions for
this system are shown below. The total system cost is shown
in Table VIII-12.
Capital-Cost Components and Assumptions for Level D:^
Flocculant feed system
Operating-Cost Assumptions for Level JD£
Operating personnel - 3 hr/day
Flocculant - 9,267 kg (20,430 Ib)/year
Power - 0.75 kW (1 hp)
Capital Investment;
Equipment
Flocculant feed system S 9,000
Contingency and contractors fee 1,170
Total Capital Investment $ 10,170
Annual Cost;
Amortization $ 1,515
Operation and Maintenance (O&M)
Operating personnel 9,450
Equipment repair and maintenance 450
Materials 20,430
Insurance IQQ
Total O6M costs $ 30,430
Electricity IQQ
Total Annual Cost $ 32,045
WASTE WATER-TREATMENT COSTS FOR SILVER-ORE CATEGORY
Silver-Ore Mines
636
-------
There are five known major silver mines in operation. The
range of ore mined is 75,280 to 1,428,000 metric tons
(83,000 to 1,574,000 short tons) annually. The mine
wastewater ranges from 246 to 4,920 cubic meters (65,000 to
1,300,000 gallons) daily.
Three of these mines are associated with mills. The
remaining two are mines alone.
A hypothetical mine, based on an arithmetic average of the
five known mines, was selected as representative for this
subcategory. The annual ore mined is 181,400 metric tons
(200,000 short tons). The average daily discharge amounts
to 1,700 cubic meters (450,000 gallons) . Three levels of
technology are considered. The total costs of achieving
these levels are shown in Table VIII-13.
Waste Water Treatment/Control
Level A;_ Sedimentation (Settling Pond)
It is assumed that a typical silver mining operation has
little or no effluent treatment or control. Level-A
technology requires the construction of a settling pond with
a 10-day retention capacity and adequate piping. No costs
are shown for pumps, since mine dewatering facilities are
already installed.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level Aj_
Settling pond - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity-of 25,500 cubic meters (6,736,000
gallons)
Land - 1.3 hectares (3.2 acres)
Piping - Flow 82m (6.6 ft)/sec through pipe measuring
12 cm (4.8 in.) x 1000 meters (3,280 feet)
Capital Investment;
Facilities
Lagoon $ 26,000
637
-------
TABLE VIII-13. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
suacATEOORY: Silver-Ore Mines
PLANT SIZE; 181,400
PLANT AGE:N/A YEARS
METRIC TOMS (2°0> OOP SHORT TONSt PER YEAR OF ore mined
PLANT LOCATION; N/A
•. COSTS Of TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSISl/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
65.6
8.0
3.0
11.0
0.06
B
114.6
15.0
20.5
2.0
37.5
0.21-
c
114.7
15.0
23.4
2.0
40.4
0.22
D
t
t
t
t
t
t
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cu
Pb
Zn
Hg
CONCENTRATION (mg/£| (ppm)
RAW
(UN-
TREATED)
25
0.1
0.2
0.7
0.004
AFTER TREATMENT TO LEVEL
A
20
0.09
0.19
0.6
0.003
B
20
0.05
0.2
0.5
0.002
C
20
0.05
0.2
0.5
0.001
D
20
0.05
0.1
0.5
0.001
E
ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT, MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: SEDIMENTATION (SETTLING POND)
LEVEL B: SEDIMENTATION, LIME PRECIPITATION. AND SECONDARY SETTLING
LEVEL C: LEVEL B PLUS SULFIDE PRECIPITATION
LEVEL D: LEVEL C PLUS OPERATING EXPERIENCE AND CLOSER CONTROL
OF OPERATING CONDITIONS OF TREATMENT SYSTEM
NO ADDITIONAL COST INCURRED
638
-------
Contingency 3,330
Total facility cost $ 29,380
Land 2,275
Equipment
Piping 30,000
Contingency and contractor's fee 3,900
Total equipment cost 33,900
Total Capital Investment $ 65,555
Annual Cost;
Amortization
Facility $ 2,990
Equipment 5,050
Total amortization S 8,040
Operation and Maintenance (OCM)
Land 20
Facility repair and maintenance 780
Equipment repair and maintenance 1,500
Taxes 55
Insurance 655
Total OSM costs 3,010
Total Annual Cost $ 11,050
Level J3£ Sedimentation, Lime Precipitation, and Secondary
Settling
The incremental cost to achieve level 8 is the cost for a
lime precipitation system, additional piping, and a
secondary settling pond. The costs associated with
sedimentation are shown under Level A.
The recommended treatment consists of the addition of 0.9 kg
of hydrated lime per 3.785 cubic meters (2 lb/1000 gallons)
of mine wastewater. The mine wastewater is then retained
for one day in a settling pond before discharge. The
incremental capital and operating ccsts and assumptions for
attaining level B are shown below. The total system cost is
shown in Table VIII-13.
639
-------
Lime precipitation system
Piping - Flow 32m (6.6 ft)/sec through pipe measuring
12 cm (4.7 in.) x 100 meters (328 feet)
Settling pond - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity of 2,550 cubic meters (671,000 gal)
Land - 0.21 hectare (0.5 acre)
Ooeratirg-Cost Assumptions for Level B;
Lime - 142 metric tons (157.5 short tons)/year
Power - 14.9 kW (20 hp)
Operating personnel - 3 hr/day
Capital Investment;
Facilities
Lagoon $ 5,100
Contingency and contractors fee 665
Total facility cost $ 5,765
Land 365
Equipment
Lime precipitation system S 35,000
Piping 3,000
Equipment subtotal 38,000
Contingency and contractors fee a,940
Total equipment cost $ 42,940
Total Capital Investment $ 49,070
Annual Cost;
Amortization
Facility $ 585
Equipment 6,400
Total amortization $ 6,985
Operation and Maintenance (OSM)
640
-------
Land 35
Operating personnel 9,450
Facility repair and maintenance 155
Equipment repair and maintenance 1,900
Materials 5,510
Taxes 10
Insurance 490
Total OSM costs 17,550
Electricity
Total Annual Cost
Level £:_ Level B plus Sulfide Precipitation
Level-c technology includes the addition of sodium sulfide
plus level-B technology.
Further removal of metals is attained by the addition of 2
mg/1 of sodium sulfide. The incremental capital and
operating costs and assumptions for sulfide precipitation
are shown below. The total cost to achieve level C is shown
in Table vm-13.
Capital-Cost Components and Assumptions for Level Cj^
Sulfide precipitation system
Operating-Cost Assumptions for Level C;_
Sodium sulfide - 1,191 kg (2,625 Ib)/year
Operating personnel - 1 hr/day
Capital Investment;
Equipment
Sulfide precipitation system $ 100
Contingency and contractor's fee 15
Total Capital Investment $ 115
Annual Cost;
Amortization 15
Operation and Maintenance (O&M)
641
-------
Operating personnel $ 3,150
Equipment repair and maintenance 5
Materials 265
Total OSM costs $ 3,420
Total Annual Cost $ 3,425
Silver Mills Employing Cvanidation, Amaqamation. Gravity
Separation, and Byproduct Recovery
Five subcategories based on milling process have been
identified for the silver milling industry. The
subcategories are essentially identical to those of the gold
industry. Four of the silver milling subcategories
(cyanidation, amalgamation, gravity separation, and
byproduct recovery) are represented by the same operation
and require the same control and treatment technology as the
gold milling industry. The capital and annual operating
costs of implementing the required treatment technologies
for these subcategories are shown in Tables VTII-9, VIII-10,
and VIII-12.
The remaining subcategory and applicable treatment
technologies are identified in the section which follows.
Silver Mills Employing Flotation Process
There are four major mills in this subcategory* These mills
process ore in the range of 75,280 to 182,300 metric tons
(83,000 to 201,000 short tons) annually. Daily wastewater
flow from these mills ranges from 1,500 to 3,160 cubic
meters (396,000 to 835,000 gallons).
An existing flotation mill which mills 180,000 metric tons
(200,000 short tons) of ore and has a daily water flow rate
of 3,160 cubic meters (835,000 gallons) was selected as a
representative operation. Typically, mills in this
subcategory recycle 70 percent of their wastewater and
discharge the remaining 30 percent.
Two levels of technology are considered. The cost of
implementing this level is shown in Table VIII-1U.
Waste Water Treatment/Control
642
-------
TABLE VI11-14. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEOORY; Silver Mills Employing Flotation Process
PLANT SIZE; 180,000 METR|C TONS (200,000 8HOBT TONS) PER YEAR OP Ore milled
PLANT APE; 23 YEARS PLANT LOCATION! Idaho
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER 1
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
55.0
8.1
22.4
4.5
35.0
0.19
B
39.0
5.7
2.1
0.3
8.1
0.045
c
^•••••••••B
D
•••••••MM
•MHMBMBB
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Cyanide
Cd**
Cu
Hg
Pb
Zn
RAW"
(UN-
TREATED
290,000
0.03
0.06
0.25
0.0098
0.42
0.37
CONCENTRATION (m«/£) (ppm)
AFTER TREATMENT TO LEVEL
A
20
0.01
0.05
0.05
0.001
0.2
0.2
B
0
0
0
0
0
0
0
c
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED). MULTIPLY COSTS SHOWN BY 0407
LEVEL A: DIVERSION DITCHING* LIME PRECIPITATION
LEVEL B: TOTAL RECYCLE
••HYPOTHETICAL
643
-------
Level Ajr. Diversion Ditching, Lime Precipitation
Adequate impoundment systems exist for mills in this
subcategory. Lime precipitation is recommended for the
precipitation of dissolved metals. The recommended dosage
is 0.9 kg of hydrated lime per 3.785 cubic meters (2 lb/1000
gallons) of wastewater. Control is also needed to divert
seasonal runoff that results in tailing pond overflow.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A:
Lime precipitation system - to treat 3,160 cubic meters
(835,000 gallons) of wastewater daily
Diversion ditching - total of 1000 meters (3,280 feet)
Operating-Cost Assumption for Level A:
Lime - 263 metric tons (390 short tons)/year
Operating personnel - 3 hr/day
Power - 39 kw (44 hp)
Capital Investment;
Facilities
Diversion ditching $1,650
Contingency and contractor's fee 215
Total facility cost $ 1,865
Equipment
Lime precipitation unit 47,000
Contingency and contractor's fee 6,110
Total equipment cost 53,110
Total Capital Investment $ 54,975
Annual Cost;
Amortination
Facility $ 190
644
-------
Equipment 7,915
Total amortination $ 8,105
Operation and Maintenance (OSM)
Operating personnel $9,450
Facility repair and maintenance 50
Equipment repair and maintenance 2,350
Material 10,000
Insurance 550
Total OSM $ 22,400
Electricity 4.490
Total Annual Cost $ 34.995
Level BZ Total Recycle (No Discharge)
Total recycle for this subcategory entails the
implementation of additional pumps and pipes to recirculate
the effluent that is normally discharged. In this case, it
is approximately 946 cubic meters (250,000 gallons) a day.
Also, diversion ditching is recommended to avoid tailing-
pond overflow resulting from seasonal runoff.
Capital-Cost Components and Assumptions for Level Bj:.
Piping - Flow aim (3.3 ft)/sec through pipe measuring
11 cm (4.3 in.) in diameter
Water pumps - 0.66 cubic meter (174 gal)/minute
Diversion ditching - 1000 meters (3,300 feet) long
Operating-Cost Assumptions for Level B:
Power - 2.2 kW (3 hp)
Capital Investment;
Facilities
Diversion ditching $ 1,650
Contingency and contractors fee 215
Total facility cost $ 1,865
Equipment
Piping 30,000
645
-------
Pumps 2,900
Equipment subtotal 32,900
Contingency and contractor*s fee 4, 280
Total equipment cost 37,180
Total Capital Investment $ 39.0
-------
respectively) per day into pits. Each discharge must be
treated separately because of the great distance between
each pit. One level of technology is considered for this
subcategory. The incremental cost of implementing this
level is shown in Table VIII-15.
Waste Water Treatment/Contro1
Level A:_ Lime Precipitation and secondary Settling
The typical bauxite mine has dewatering pumps, pipes, and
primary settling ponds. The installation of additional
piping, a lime precipitation system, and secondary settling
ponds for each discharge is needed to achieve level A.
The addition of. 0.9 kg of hydrated lime per 3.785 cubic
meters of mine water (2 lb/1000 gallons), followed by a 2-
day retention in the secondary settling ponds, is considered
adequate treatment for this subcategory.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A;
Three lime precipitation units -
17,000 cubic meters (4,500,000 gal)/day
7,570 cubic meters (2,000,000 gal)/day
3,785 cubic meters (1,000,000 gal)/day
Three secondary settling ponds -
all have dike height of 3 m (10 ft) and are 3
meters (10 ft) wide
capacities of 50,000 cubic meters (13,209,000 gal)
25,000 cubic meters (6,604,000 gal)
12,000 cubic meters (3,170,000 gal)
Piping - Flow 92m (6.6 ft)/sec through pipes measuring:
36 cm (14 in.) x 100 meters (328 feet)
24 cm (9.4 in.) x 100 meters (328 feet)
17 cm (6.7 in.) x 100 meters (328 feet)
Land - 4.3 hectares (10.6 acres)
Operating-Cost Assumptions for Level A£
Lime - 2,380 metric tons (2,625 short tons)/year
647
-------
TABLE VIII-15. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE
8UBCATEOORV:
Bauxite Mines
PLANT SIZE; 861,650
PLANT AGE
. 75
YEARS
METRIC TONS ( 950.000 SHORT TONS) PER YEAR OF
PLANT LOCATION; Arkansas
mined
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
383.2
51.7
149.5
25.3
226.5
0.26
B
t
t
t
t
t
t
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Al
Fe
Zn
CONCENTRATION (mo/A) (ppm)
RAW
(UN-
TREATED)
161.0
47.8
39.2
0.23
AFTER TREATMENT TO LEVEL
A
20
0.6
0.5
0.1
B
20
0.5
0.30
0.1
c
D
E
'ORE MINED. To OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.907
fNO COST DIFFERENCE
LEVEL A: LIME PRECIPITATION AND SECONDARY SETTLING
LEVEL B: LIME PRECIPITATION AND SECONDARY SETTLING WITH OPTIMUM pH CONTROL
648
-------
Power - 186 kW (250 hp)
Operating personnel - 3 hr/day/unit * 12 hr/day
Capital Investment;
Facilities
Contingency and contractor's fee 10 ,425
Total facility cost * 90,625
Land 7'525
Equipment
Lime precipitation units
, 252
Equipment subtotal ??
contingency and contractor's fee
Total equipment cost »
Total Capital Investment * 383,195
Annual Cost:
Amortization
Facility $ I'***
Equipment € fe, '71Q
Total amortization $ 5l,7iu
Operation and Maintenance (OCM)
Land __
Operating personnel i'
Facility repair and maintenance n,
Equipment repair and maintenance f
Materials 91,
190
TaxeS 3 830
Insurance
Total O6M costs
Electricity 25f365
649
-------
Total Annual Cost $ 226,540
WASTE WATER TREATMENT COSTS FOR FERROALLOY-ORE CATEGORY
Ferrga11 oy-Ore Mines
There are seven ferroalloy mines in this subcategory. The
annual ore production ranges from 16,560 to 14,000,000
metric tons (18,220 to 15,500,000 short tons). The range of
daily wastewater discharged is 0 to 51,840 cubic meters (0
to 13,700,000 gallons).
A hypothetical mine, based on the industry average, was
selected as representative. This mine is assumed to have an
annual ore production of 1,800,000 metric tons (1,990,000
short tons), with a daily discharge of 3,275 cubic meters
(865,000 gallons).
The current level of technology for this subcategory
includes flocculation, neutralization, and settling or
clarifying. A further level of technology has been
recommended. The total costs of achieving this level are
shown in Table VIII-16.
Waste Water Treatment/Control
Level A; Lime Precipitation and Secondary Settling
The necessary equipment includes a lime precipitation unit
and a settling pond. The addition of 0.9 kg of hydrated
lime per 3.785 cubic meters (2 lb/1000 gallons) of
wastewater is considered sufficient for precipitation of
metals. The wastewater is then retained for one day in a
settling pond before discharge. The capital and operating
costs and assumptions for attaining this level are shown
below.
Capital-Cost Components and Assemptions for Level Aj.
Lime precipitation system
Settling pond - dike height of 3 meters (10 feet)
top width of 3 meters (10 feet)
capacity of 4,900 cubic meters (1,295,000 gal)
»
Land - 0.35 hectare (0.85 acre)
650
-------
TABLE VIII-16. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
suBCATEQORY! Ferr°alloy-Ore Mines
PLANT SIZE: 1,800,000 METRIC TONS (1,990,000 SHORT TONS) PER YEAR OP Ore mined
PLANT AGE:N/A YEARS PLANT LOCATION; N/A
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS($)/METRIC TON OF PRODUCT*
COSTS (SI 000) TO ATTAIN LEVEL
A
93.8
14.0
25.1
12.5
51.6
0.028
B
t
t
t
t
t
t
C
o
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
As
Cd
Cu
Mo
Pb
In-
CONCENTRATION (mgtf) (ppm)
RAW
(UN-
TREATED)
50
1
0.14
0.5
2
0.25
0.6
AFTER TREATMENT TO LEVEL
A
20
0.5
0.05
0.05
1.0
0.2
0.5
B
20
0.5
0.05
0.05
1.0
0.1
0.1
C
o
E
ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT, MULTIPLY COSTS SHOWN BY 0407
fNO COST DIFFERENCE
LEVEL A: LIME PRECIPITATION AND SECONDARY SETTLING
LEVEL B: LEVEL A WITH OPERATING EXPERIENCE AND CLOSER CONTROL
OF OPERATING CONDITIONS
651
-------
Piping - Flow a 2 meters (6.6 feet)/second through pipe
measuring 16 cm (6.3 in.) x 100 meters (328 ft)
Operating-Cost Assumptions for Level A;
Lime - 275 metric tons (302 short tons)/year
Operating personnel - 3 hr/day
Power - 32 kw (43 hp)
Capital Investment;
Facilities
Lagoon $ 8,000
Contingency and contractors fee 1.040
Total facility cost $ 9,QUO
Land 615
Equipment
Lime precipitation unit 49,000
Piping 3,700
Equipment subtotal 52,700
Contingency and contractor's fee 6,850
Total equipment cost 59.550
Total Capital Investment S 69,205
Annual Cost;
Amortization
Facility $ 920
Equipment 8,875
Total amortization $ 9,795
Operation and Maintenance (OSM)
Land 60
Operating personnel 9,450
Facility repair and maintenance 240
Equipment repair and maintenance 2,635
Materials 10,570
Taxes 15
Insurance 690
Total OSM costs 23,660
Electricity 4,320
652
-------
Total Annual Cost $ 37,775
Ferroalloy Mine/Mills Annually Processing Less Than 5,000
Metric Tons (5,500 Short Tons) Ore By Methods other Than ore
Leaching Ore Leaching ——
There are 50-60 operations in this subcategory. All are
located in the western U.S. The annual amount of ore milled
ranges from 0 to 5,000 metric tons (0 to 5,500 short tons).
The daily wastewater flow ranges from 0 to 1,872 cubic
meters (0 to 500,000 gallons).
Mills in this subcategory are small and operate 100 days a
year or less. The mine associated with each mill is assumed
to discharge 350 days and to require treatment of the mine
water year-round.
A typical operation in this subcategory mines and mills
approximately 500 metric tons (550 short tons) a year. The
daily wastewater flow is 55 cubic meters (14,500 gallons).
Two levels of technology are considered. The costs of
achieving these levels are shown in Table VIII-17.
Waste Water Treatment Control
Level AJ. settling Pond
The equipment and facilities necessary to achieve this level
include a pond and additional piping.
The capital and operating costs are as follows:
Capital Ihverstment:
Facilities
Settling Pond $ 500
Contingency and contractors fee 65
Total facility cost $ 565
Equipment
Piping
Contingency and contractor's fee
Total equipment cost
653
-------
TABLE VIII-17. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
Ferroalloy Mine/Mill Annually Processing Less than 5000 Metric Tons
SUBCATEGORv;(5,500 Short Tons) Ore by Methods Other than Ore Leaching
500 METRIC TOMS f 550
PLANT SIZE:
PLANT AGE:N/A YEARS
_METR|CTONS(
PLANT LOCATION:
SHORT TONS) PER YEAR OF ore mined and milled
N/A
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
1.7
0.23
0.08
0.31
0.62
B
5.4
0.78
0.37
0.25
1.40
2.80
c
8.8
1.29
0.62
0.50
2.41
4.82
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
CONCENTRATION (mg/ I) tppml
RAW
(UN-
TREATED)
250,000
AFTER TREATMENT TO LEVEL
A
30
B
30
c
30
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED). MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: SETTLING POND
LEVELS: LEVEL A PLUS pH CONTROL
LEVEL C: LEVEL B PLUS FLOCCULATION
654
-------
Total Capital Investment $ 1,695
Annual Cost;
Amortization
Facility
Equipment
Total amortization
Operation and Maintenance (O&M)
Facility repair and maintenance 15
Equipment repair and maintenance 50
Insurance 15
Total OSM Cost 80
Total Annual Cost $ 310
Level BI settling Pond and pj Control at Selected
Operations
A few operations in this subcategory will need to raise the
pH of their mine water from about 5 to a minimum of 6.5. To
do this the addition of 0.45 kg of lime per 3.785 cubic
meters (1 lb/1000 gallons) of wastewater is recommended.
Cost for operating personnel is not included. It is assumed
that the owners of these operations do the necessary work
themselves.
The incremental capital and operating costs for Level B are
shown below. The total costs of achieving Level B are shown
in Table VIII-17.
Capital Investment;
Equipment
Mixing tank
Slurry Pump
Equipment subtotal
Contingency and contractor's fee
Total Capital Investment
Annual Cost;
Amortization
655
-------
Operation and Maintenance (O&M)
Equipment repair and maintenance
Materials
Insurance
Total O&M Costs
Electricity
Total Annual Cost
Level C; Level B plus Flocculation
$ 165
85
40,
$ 290
$1095
In addition to Level B treatment, flocculation would be
necessary for mill water at selected operations. This would
be needed for only 100 days a year.
A full day supply of flocculant, in a 0.2 percent solution
that is prepared daily, is fed to the wastewater stream at a
rate of 5 mg/1. The total cost of Level C treatment is
shown in Table VIII-17.
The incremental costs for achieving Level C are shown below.
Capital Investment;
Equipment
Mixing tank $
Feed pump
Equipment subtotal
Contingency and contractor1s fee
Total Capital Investment $3390
Annual Cost:
Amortination 505
Operation and Maintenance (O&M)
Equipment repair and maintenance
Materials
Insurance
Total A&M Costs
Electricity
$ 150
60
35
205
255
656
-------
Total Annual Cost $ 1005
Ferroalloy Mills Annually Processing More Than 5,000 Metric
Tons (5,500 Short Tons) Ore By Physical Methods
There are two mills in this subcategory, both of which are
located in the western U.S. The annual amount of ore milled
ranges from 7,200 to 1,800,000 metric tons (7,925 to
1,990,000 short tons). The daily wastewater flow ranges
from 30 to 17,425 cubic meters (7,925 to 4,603,700 gallons).
A hypothetical mill was chosen to represent this
subcategory. The average annual milling capacity is 525,000
metric tons (577,500 short tons), with a daily discharge of
4,920 cubic meters (1,300,000 gallons).
Three alternative levels of technology are considered. The
total costs of implementing these levels are shown in Table
VIII-18.
Waste Water Treatment/Control
Level Aj. Lime Precipitation
Level-A treatment consists of lime precipitation and
settling. The necessary settling ponds are currently
available; therefore, no cost estimates for these facilities
have been made. The addition of 1.36 kg of hydrated lime
per 3785 cubic meters (3 lb/1000 gallons) of water would be
necessary to raise the pH sufficiently for precipitation of
metals.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A£
Lime precipitation system
Operating-Cost Assumptions for Level A^
Lime - 618 metric tons (682 short tons)/year
Operating personnel - 3 hr/day
Power - 37 kW (50 hp)
657
-------
TABLE VIII-18. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MILL
Ferroalloy Mills Annually Processing More Than 5,000 Metric
SUBCATEGORY: Tons f5r512 Short Tons') Ore bv Physical Methods
PLANT SIZE: 525. OQQ METRIC TONS ( 577.500 SHORT TONS) PER YEAR OF ore milled
PLANT AGE; N/AYEARS
PLANT LOCATION: N/A
•. COSTS Of TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS ($»/METRIC TON OF PRODUCT*
COSTS 1*1000) TO ATTAIN LEVEL
A
70.0
10.4
37.1
5.0
52.5
0.10
B
64.2
9.6
3.5
1.0
14.1
0.027
C
134.2
20.0
40.6
6.0
66.6
0.127
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
As
Cd
Cu
Mo
Zn
CONCENTRATION (ma/ il (ppml
RAW
(UN-
TREATED)
300,000
0.6
0.1
0.5
5
0.2
AFTER TREATMENT TO LEVEL
A
20
0.5
0.05
0.05
0.2
B
0
0
o
0
o
0
C
20
0.5
0.05
0.05
1.0
0.1
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED). MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION
LEVEL B: TOTAL RECYCLE (ZERO DISCHARGE)
LEVEL C: LEVEL A PLUS (LEVEL B WITHOUT ZERO DISCHARGE)
658
-------
Capital Investment;
Lime precipitation unit $ 62,000
Contingency and contractors fee 3,050
Total Capital Investment $ 7Q,Q6Q
Annual Cost;
Amortization $ 10,440
Operation and Maintenance (O5M)
Operating personnel $ 9,450
Equipment repair and maintenance 3,100
Materials 23,870
Insurance 700
Total OSM costs $ 37,120
Electricity
Total Annual Cost
Level B£ Total Recycle (Zero Discharge)
Mills in this subcategory recycle approximately 60 percent
of their process water. The remaining 40 percent (1,968
cubic meters, equivalent to 520,000 gallons, per day) is
discharged Level-B technology requires additional pumps and
piping to attain total recycle.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level E£
Piping - Flow a 2 meters (6.6 feet)/second through pipe
measuring 12 cm (5 in.) x 1,750 meters
(5,740 feet)
Pumps - water pumps rated at 1,968 1 (361 gal)/min
Operatinq-Cost Assumptions for Level B^
Power - 7.5 kW (10 hp)
Capital Investment;
Piping $ 52,500
659
-------
Pumps 4,300
Equipment subtotal 56,800
Contingency and contractor's fee 7.385
Total Capital Investment $ 64.185
Annual Cost:
Amortization 9,565
Operation and Maintenance (OSM)
Equipment repair and maintenance $ 2,810
Insurance 640
Total OSM costs 3,480
Electricity 1,000
Total Annual Cost $ 14,045
Level C; Level A plus Level B
Level-c technology is applicable in areas where there is
excess water. The total cost of attaining this level is the
sum of the costs of attaining levels A and B. These costs
are shown in Table VIII-18.
Ferroalloy Mills Annually Processing More Than 5.000 Metric
Tons (5,500 Short Tons! Ore By Flotation
There are four mills in this subcategory, all of which are
located in the western U.S. The range of ore milled is
7,200 to 15,480,000 metric tons (7,925 to 17,030,000 short
tons) annually. The daily mill wastewater ranges from 30 to
94,600 cubic meters (7,925 to 25,000,000 gallons).
A hypothetical mill with an annual milling capacity of
5,600,000 metric tons (6,160,000 short tons) and with a
daily wastewater flow of 22,710 cubic meters (6,000,000
gallons) is representative for this subcategory. Four
levels of technology are considered. The total costs of
achieving these levels are shown in Table VTII-19.
Waste Water Treatment/Control
660
-------
TABLE VI11-19. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MILL
Ferroalloy Mills Annually Processing More Than 5,000 Metric
SUBCATEOORY: Tons T5.512 Short Tons! Ore bv
PLANT SIZE; 5.600.000
PLANT APE; N/AY EARS
.METRIC TONS (6.160.000 SHORTTONS)PER YEAR OF org ni 1 ]
PLANT LOCATION; N/A
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS (SI/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
126.6
18.9
104.5
10.7
134.1
0.023
B
113.0
16.8
6.1
12.3
35.2
0.006
c
252.1
36.1
70.5
20.6
127.2
0.022
o
269.7
39.7
53.1
13.3
106.1
0.02
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
COD
Cyanide
As
Cd
Cu
Ho
Zn
RAW
(UN-
TREATED)
500,000
135
0.45
0.6
0.74
51
17
50
CONCENTRATION (mg/£) (ppm)
A
20
50
0.05
0.5
0.05
0.05
_
0.2
AFTER TREATMENT TO LEVEL
B
0
0
0
0
0
0
0
0
c
20
25
0.02
0.5
0.05
0.05
1.0
0.1
D
20
25
0.02
0.5
0.05
o.'os
1.0
0.1
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION AND DISCHARGE
LEVEL B: TOTAL RECYCLE
LEVEL C: LEVEL B PLUS FERRIC SULFATE ADDITION, FLOCCULATION, SETTLING, LIME NEUTRALIZATION,
SECONDARY SETTLING, AND AERATION
LEVEL D: LEVEL B PLUS AERATION, SETTLING. AND ION EXCHANGE
661
-------
Level A; Lime Precipitation and Discharge
The settling ponds necessary for adequate precipitation and
settling are considered to be already installed. The
addition of 1.36 kg of pebbled lime per 3785 liters (3.0
lb/1000 gallons) of water is necessary for precipitation.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and As sumpt ions for Level A;
Lime precipitation unit
Operating-Cost Assumptions for Level A;
Operating personnel - 3 hr/day x 360 days/year
Lime - pebbled, quantity of 2,857 metric tons (3,150
short tons)/year
Power - 75 kw (100 hp)
Capital Investment:
Equipment
Lime precipitation unit S 112,000
Contingency and contractor's fee 11,560
Total equipment cost 126,560
Total Capital Investment S 126.560
Annual Cost:
Amortization $ 18,860
Operation and Maintenance (O&M)
Operating personnel $ 9,450
Equipment repair and maintenance 5,600
Materials 88,200
Insurance 1,265
Total O6M costs $ 10U,515
Electricity 10,700
662
-------
Total Annual Cost $ 134,075
Level BJ!_ Total Recycle
To achieve total recycle, additional piping and pumps would
be necessary. The implementation of a total-recycle system
does not necessarily imply no discharge. The problem of
excess water due to rainfall still exists. The capital and
operating costs and assumptions for attaining this level are
shown below.
Capital-Cost Components and Assumptions for Level B:
Pumps - water pumps rated at 15,770 1 (4,163 gal)/min
Piping - Flow a 2 meters (6.6 feet)/sec through pipe
measuring 42 cm (16.5 in.) x 1000 meters
(3,280 feet)
Operating-Cost Assumptions for Level BJI
Power - 89 kW (120 hp)
Capital Investment;
Equipment
Piping $ 21,000
Pumps 79;000
Equipment subtotal 100,000
Contingency and contractor's fee 13,000
Total Capital Investment $ 113,000
Annual Cost;
Amortization $ 16,840
Operation and Maintenance (OSM)
Equipment repair and maintenance $ 5,000
Insurance 1,130
Total O&M costs 6,130
Electricity 12,250
Total Annual Cost $ 35,220
663
-------
Level C; Level B plus Ferric Sulfate Addition, FlPeculation,
Settling, Lime Neutralization, Secondary Settling/
and Aeration
Level-C technology may be applied in areas of excess water.
It is assumed that 25 percent of the mill wastewater is bled
and discharged--a daily total of 5,677 cubic meters
(1,500,000 gallons). The treatment recommended for mills in
this subcategory is the addition of 75 mg/1 of ferric
sulfate and 5 mg/1 of flocculant to the wastewater stream.
Acid is also added to lower the pH to 4.5; however, no cost
is shown for this item, as the cost is negligible. The
fc-astewater is then contained for one day in a settling pond.
Prior to discharge, the wastewater is neutralized with Lime
(0.45 kg/3.785 cubic meters, equivalent to 1 lb/1,000
gallons) and contained in an aerated pond. Aeration is
needed to lower COD and to convert cyanide to cyanate. The
capital and operating costs and assumptions for attaining
this level are shown below.
Capital-Cost Components and Assumptions for Level C:
2 Settling ponds - dike height of 3 m (10 ft)
top width of 3 m (10 ft)
capacity of 8,516 cubic meters
(2,250,000 gal)
Land - 1.06 hectares (2.6 acres)
Ferric sulfate addition - 2 mix tanks with capacity of
14.2 cubic meters (3,750
gallons)
1 metering pump
Flocculation system
Lime neutralization system
Aerator - 18 kw (24 hp)
Piping - Flow a 2 meters (6.6 feet)/sec through pipe
measuring 21 cm (8.3 in.) x 200 meters
(656 feet)
Operating-Cost Assumptions for Level C:
Operating personnel - 6 hr/day
Materials - lime a 236 metric tons (260 short tons)/year
664
-------
ferric sulfate 3 1U9 metric tons (163 short
tons)/year ,
flocculant 3 9.9 metric tons (10.9 short
tons)/year
Power - 60 kW (81 hp)
Capital Investment:
Facilities
Lagoons $ 22,000
Contingency and contractor's fee 2,860
Total facility cost $ 24,860
Land 1,860
Equipment
Ferric sulfate system 12,550
Flocculation system 1U,900
Lime neutralization unit 55,000
Piping 9,000
Aeration equipment 8,000
Equipment subtotal 99,U50
Contingency and contractor1s fee 12,930
Total equipment cost 112,380
Total Capital Investment S139,100
Annual Cost:
Amortization
Facility $ 2,530
Equipment 16,750
Total amortization $ 19,280
Operation and Maintenance (OSM)
Land $ 185
Operating personnel 18,900
Facility repair and maintenance 660
Equipment repair and maintenance 1,975
Materials
Taxes
Insurance
665
-------
Total OSM costs $ 64,390
Electricity 8,270
Total Annual Cost $ 91,940
Level D: Level B plus Aeration, Settling, and Ion Exchange
Level-D treatment is an alternative to level-C treatment.
Level-D technology may be applied in areas of excess water.
It is assumed that 10 percent of the mill wastewater is dis-
charged (a total of 2,271 cubic meters, equivalent to
600,000 gallons). This level of treatment includes ar.
aeration pond and an ion-exchange unit.
The excess wastewater is contained for one day in an
aeration pond to lower COD from 100 mg/1 to 20 mg/1 and to
convert cyanide to cyanate. The wastewater is then passed
on to an ion-exchange unit for further treatment before
discharge. The amount of ion-exchange resin actually needed
would depend upon the characteristics of the wastewater.
For the purposes of this report, it is assumed that 5,5
cubic meters (7.2 cubic yards) of resin would be adequate.
The capital and operating costs and assumptions for attain-
ing this level are shown below.
Capital-Cost Components and Assumptions for Level D:
Settling pond - dike height of 3 m (10 ft)
top width of 3.m (10 ft)
capacity of 3,400 cubic meters
(898,200 gallons)
Land - 0.26 hectare (0.64 acre)
Aerator - 7.5 kw (10 hp)
Ion Exchanger - capacity of 5.5 cubic meters (7.1 cubic yards)
Piping - Flow a 2 meters (6.6 feet)/sec through pipe
measuring 13 cm (5 in.) x 100 meters (328 feet)
Operating-Cost Assumptions for Level D:
Operating personnel - 10.8 hr/day
Resins - replacement every 3 years
666
-------
Power - 7.5 kW (10 hp)
Capital Investment;
Facilities
Lagoon $ 6,200
Contingency and contractor's fee 805
Total facility cost $ 7,005
Land 455
Equipment
Aeration unit 3,UOO
Ion exchanger 125,000
Piping 3.200
Equipment subtotal $ 131,600
Contingency and contractor's fee 17,110
Total equipment cost 148,710
Total Capital Investment $156.170
Annual Cost;
Amortization
Facility $ 715
Equipment 22.165
Total amortization $ 22,880
Operation and Maintenance (OCM)
Land
Operating personnel
Facility repair and maintenance
Equipment repair and maintenance
Materials
Taxes
Insurance
Total OGM costs
Electricity 1,020
Total Annual Cost $ 70,885
667
-------
Ferroalloy Mills Practicing Ore Leaching
There is only one ferroalloy mill in this subcategory, and
it is located in the southeastern U.S. The ore milled
annually is 410,400 metric tons (451,500 short tons), with a
daily wastewater discharge of 5,300 cubic meters (1,400,000
gallons) .
There are four levels of technologies considered. The total
costs of achieving these levels are shown in Table VIII-20.
Waste water Treatment/Control
Level A: Lime Precipitation, Thickener, sludge Pond,
and Surge Pond
Because of the high buffering effects of salts in the
wastewater the addition of 2.25 kg of pebbled lime per 3.785
cubic meters (5 lb/1000 gallons) of wastewater is required
for precipitation. The capital and operating costs and
assumptions for attaining this level are shown below.
Capital Cost Components and Assumptions for Level A;
Sludge pond - dike height 3 meters (10 ft)
top width of 3 meters (10 ft)
capacity of 10,000 cubic meters
(2,640,000 gal).
Surge pond - dike height 3 meters (10 ft)
top width of 3 meters (10 ft)
capacity of 7950 cubic meters
(2,100,000 gal)
Lime precipitation system
Land - 1.1 hectares (2.7 acres)
Piping - flow at 1 meter (3.3 feet)/sec through pipe
measuring 29 cm (11.5 in) x 1000 meters
Sludge pumps - rated at 370 liters (98 gallons)/min
Thickener - 1 hour retention; continuous flow
250 cubic meter capacity (66,050 gallons)
Operating Cost Assumptions for Level A;
Operating personnel - 4 hr/day
668
-------
TABLE VIII-20. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGQRY: Ferroalloy Mill Practicing Ore Leaching
PLANT SIZE: 410.400 METRIC TONS (451, 500 SHORT TONS) PER YEAR OF Ore mill
PLANT AGE:N/A YEARS PLANT LOCATION: N/A
*. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER*
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS IS1000) TO ATTAIN LEVEL
A
280.0
40.1
61.7
5.7
107.5
0.26
B
424.2
61.6
384.9
16.7
463.2
1.13
c
429.2
62.5
385.1
16.7
464.3
1.13
D
490.5
70.9
388.3
29.3
488.5
1.19
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Ammonia
As
Cd
Cr
Cu
Zn
CONCENTRATION (mg/4) (ppm)
RAW
(UN-
TREATED)
300,000
1200
0.6
0.3
1.1
0.3
4
AFTER TREATMENT TO LEVEL
A
20
1200
0.5
0.05
1.1
0.05
0.2
B
20
30
0.5
0.05
1.1
0.05
0.2
c
20
30
0.5
0.05
0.05
0.05
0.1
D
20
5
0.5
0.05
0.05
0.05
0.1
E
*ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A- LIME PRECIPITATION. THICKENER, SLUDGE AND SURGE POND
LEVEL B-' LEVEL A PLUS AMMONIA STRIPPING
LEVEL C: LEVEL B PLUS SULFUR DIOXIDE INJECTION
LEVEL D LEVEL C PLUS AERATION
669
-------
Lime - 1111 metric tons/year (1225 short tons)
Power - 57 hp
Capital Investment;
Facilities
Sludge and Surge pond $ 24,500
Contingency and contractor's 3,200
fee
Total facility cost $ 27,700
Land 1,925
Equi pme nt
Lime precipitation system $ 76,050
Thickener 85,000
Piping 56,000
Sludge 4,500
Equipment Subtotal 221,550
Contingency and Contractor's
fee 28,800
Total equipment cost 250,350
Total Capital Investment $ 279,975
Annual Cost:
Amortization
Facility 2,700
Equipment 37,300
Total amortization $ 40,000
Operation and Maintenance(OSM)
Land 190
Operating personnel 12,600
Facility repair S maintenance 735
Equipment repair & maintenance 11,080
Materials 34,220
Taxes 50
Insurance 2,800
Total OSM costs 61,675
Electricity 5,700
Total Annual Cost $ 107,445
670
-------
Level B; Level A plus Ammonia Stripping
Level B technology suggests that 10 percent of the
wastewater (530 cubic meters, equivalent to 140,000 gallons)
be segregated from the rest of the mill wastewater. This
water is contaminated with large amounts of ammonia. TO
remove the ammonia, the wastewater must first be treated
with caustic soda to raise the pH to 11. The wastewater
must then be sent to an air stripper, which will remove 90
to 95 percent of the ammonia.
The costs for ammonia stripping have been provided by
surveyed operations. The capital and operating costs and
assumptions for attaining this level are shown below.
Total costs for level B are shown in Table VIII-20.
Capital Cost Components and Assumptions for Ammonia
Stripping
Piping - flow at 1 meter (3.3 ft) sec through pipe measuring
9 cm (3.5 in) x 1000 meters (3280 feet)
Pumps - slurry type, rated at 370 liters (98 gallons)/min
Ammonia stripper - packed column at $33,000
fan at $9,000
Caustic soda addition - mix tank with capacity of 228
cubic meters (60,000 gallons)
liquor feed pump with capacity
of 9as liters/hour (250
gallons)
instrumentation on mix tank for
pH check/control
Operating Cost Assumptions for Ammonia Stripping
Operating personnel - 3 hour/shift, 3 shift/day
Caustic soda - 3500 metric tons (3880 short tons) at
f82/metric ton ($74.38 short ton) '
Power - 110 hp
671
-------
Capital Investment;
Equipment
Caustic soda addition $ 56,100
Ammonia stripper 42,000
Piping 25,000
Pumps 4,500
Equipment subtotal $ 127,600
Contingency and Contractor's
fee 16,590
Total Capital Investment $ 144.190
Annual Cost
Amortization 21,485
Operation and Maintenance (OSM)
Operating personnel $ 28,350
Equipment repair and
maintenance 6,380
Materials 287,000
Insurance 1,440
Total OSM S 323,170
Electricity S 11.000
Total Annual cost S 355.655
Level C; Level B plus Sulfur Dioxide In-jection
Sulfur dioxide injection is required for chromium reduction.
The sulfur dioxide injection system requires a holding tank,
ejector, and sulfur dioxide. Total costs for Level C. are
shown in Table VIII-20. The incremental capital and
operating costs and assumptions for attaining this level are
shown below.
Capital Cost Components and Assumptions for Level C:
Sulfur dioxide injectin system - 1 holding tank with
retention time of 5 minutes and a capacity of 18,400 liters
(4,860 gallons)
Ejector
Operating Cost Assumptions for Level C;
672
-------
Sulfur dioxide - amount needed is low and is presumed to be
readily available.
Capital Investment:
Equipment
Ejector $1,000
Sulfur dioxide injection tank 3,400
Equipment subtotal 4,400
Contingency and contractors fee 570
Total Capital Investment $
Annual Cost;
Amortization 890
Operation and Maintenance (O6M)
Equipment repair and maintenance 220
Insurance 50
Total OSM 270
Total Annual Cost $ 1,160
Level D; Level C plus Aeration
Further treatment would include the merging of the waste
streams into an aerated pond. The purpose of aeration is to
lower COD. A one-day retention is recommended before
discharge.
The capital and operating costs and assumptions for
attaining this level are shown below. Total costs for Level
D are shown in Table VIII-20.
Capital cost Components and Assumptions for Level D:
Pond - dike height of 3 meters (10 ft); top width of 3
meters; and capacity 7,950 cubic meters (2,100,000 gallons)
Land - 0.5 hectare (1.2 acres)
Aerator - 94 kW (126 hp)
Capital Investment;
Facilities
673
-------
Pond $ 11,500
Contingency and contractor's
fee 1,495
Total facilties cost $ 12,995
Land 875
Equipment
Aerator $ 42,000
Contingency and contractor's fee 5,460
Total equipment cost 47,460
Total Capital Investment $ 61,330
Annual Cost;
Amortization
Facility 1,325
Equipment 7,075
Total amortization $ 8,400
Operation and Maintenance (O6M)
Land 90
Facility repair and maintenance 345
Equipment repair and maintenance 2,100
Taxes 20
Insurance 615
Total 05M cost 3,170
Electricity 12,600
Total Annual Cost $ 24,170
WASTE WATER TREATMENT COSTS FOR MERCURY-ORE CATEGORY
Mercury-Ore Mines
The exact number of operating mercury mines is difficult to
determine at present. One open-pit mine is currently con-
sidered active; however, it does not have a discharge and is
closed seasonally.
Currently, existing market conditions have resulted in
almost no activity from underground mercury mines. It is
674
-------
expected that, with a return to more favorable market
conditions, some underground mines will again become active.
In anticipation of a rise in the market price of mercury, a
hypothetical mine was chosen to represent this subcategory.
The representative mine has an annual ore production of
27,210 metric tons (30,000 short tons) with a daily
wastewater flow of 378.5 cubic meters (100,000 gallons).
One level of technology is considered. The total costs of
achieving this level are shown in Table VIII-21.
MERCURY ORE MINES
Waste Water Treatment Control
Level A:, Lime Precipitation, Settling and Discharge
The addition of 1.36 kg of hydrated lime per 3.785 cubic
meters (3.0 lb/1000 gallons) to the wastewater is
recommended for precipitation of metals.
A 15 day supply of hydrated lime (2,040 kg equivalent to
4,U88 Ibs) is stored as a slurry (0.9 kg/3.785 1, equivalent
to 2 lb/1 gallon) in a mixing tank. A portion of the slurry
is drawn off and mixed with the mine water in another mixing
tank for 15 minutes, then is pumped into a settling pond.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital cost Components and Assumptions for Level A:
2 ,Ponds - dike height 2m (7 feet); top width of 3 m (10
feet) and capacity of 570 cubic meters (150,600 gallons)
Land - 0.2 hectare (0.5 acre)
Lime precipitation system -
slurry storage tank with capacity of 8,580 liters (2,265
gallons) and containing a 15-day supply of lime slurry.
mix tank with retention time of 15 minutes and capacitv
of 3,975 liters (1,050 gallons), based on flow of 265
liters (70 gallons) per minute.
Pump with capacity of 265 liters (70 gallons) per
minute.
675
-------
TABLE VIII-21. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE
suBCATEGQRY: Mercury-Ore Mines
PLANT SIZE: 27,210
PLANT AGE: N/AyEARS
_METRIC TONS (30,000
PLANT LOCATION: N/A
SHORT TONS) PER YEAR OF ore mined
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING ANO MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($10001 TO ATTAIN LEVEL
A
29.5
4.2
6.5
1.1
11.8
0.43
B
29.6
4.2
9.7
1.1
15.0
0.55
c
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Hg
Ni
CONCENTRATION (mg/£> (ppro)
RAW
(UN-
TREATED)
25
0.001
0.2
AFTER TREATMENT TO LEVEL
A
20
0.001
0.1
B
20
0.0005
0.1
c
D
E
ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION AND DISCHARGE
LEVEL B: LEVEL A AND SULFIDE PRECIPITATION
676
-------
Piping - flow at 2m (6.6 feet)/sec through pipe
measuring 5 cm (2 inches) x 1,100 meters (3,608 feet)
Operating Cost Assumptions for Level A:
Lime - 47.5 metric tons (53 short tons)/year
Operating personnel - 1 hr/day
Power - 8.2 kw (11 hp)
Capital Investment;
Facilities
Lagoons S 3,400
Contingency 6 contractor's fee 440
Total Facility Cost $ 3,840
Land 350
Equipment
Lime precipitation 6,950
Piping 15,400
Equipment Subtotal 22,350
Contingency 6 contractor's fee 2,905
Total equipment cost 25,255
Total Capital Investment $ 29.445
Annual Cost
Amortization
Facility * 390
Equipment 3,765
Total Amortization S 4,155
Operation and Maintenance (O6M1
Land
Operating personnel 3«
Facility repair 6 maintenance 100
Equipment repair and maintenance 1,115
Materials 1»855
Taxes iu
677
-------
Insurance 295
Total OSM Costs $ 6,560
Total Annual Cost 11.815
Level Bj_ Level A^ sulfide Precipitation and Discharge
Level B technology consists of level A plus sulfide
precipitation. The addition of 1 mg sodium sulfide to one
liter of wastewater (1 ppm) is recommended for
precipitation.
The capital and operating costs for sulfide precipitation
are shown below. Total costs for level E are shown in Table
VIII-21.
Capital Cost Components and Assumptions for Sulfide
Precipitation;
Free ipi tation;
Sulfide precipitation system - drum with capacity of 208
liters (55 gal)
Operating Cost Assumptions for Sulfide Precipitation „
Sodium sulfide - 132 kg (291 Ib)/year
Operating personnel 1 hr/day
Capital Investment:
Equipment
Sulfide precipitation unit € 100
Contingency and contractor's fee 15
Total Capital Investment $ US
Annual Cost;
Amortization $ 15
Operation and Maintenance (O6M)
Operating personnel $3,150
Equipment repair 8 maintenance 5
Materials 30
678
-------
Total O6M Cost $3,195
Total Annual Cost $3,200
Mercury Mills Employing Flotation Process
There are no mills currently operating in this subcategory.
A mill utilizing a flotation process is due to open in 197s!
This mill was chosen to be representative for this subcate-
gory. it is expected to mill 159,000 metric tons (175,000
short tons) a year. Discharge of wastewater is expected to
be 7,570 cubic meters (2,000,000 gallons) daily.
The recommended level of treatment is zero discharge of
wastewater. Two alternatives for achieving zero discharge
are considered. They are total recycle, or impoundment and
evaporation. The costs of implementing these alternatives
are shown in Table VIII-22.
Waste Water Treatment/Control
Level A: Total Recycle (Zero Discharge)
The facilities required to achieve total recycle include a
rectangular pond of 40 hectares (100 acres) whose length is
equal to twice its width. The pond would also require one
transverse dike to provide two separate ponds, each having
an area of 20 hectares (50 acres). The first pond would be
used for sedimentation of suspended solids. The second pond
would be used as a polishing pond. Water in the polishing
pond would be recycled back to the mill.
Diversion ditching along one length and one width is recom-
mended to avoid stress in the system due to seasonal runoff.
Additional equipment includes a tailing-disposal system and
decant pumps and pipes. The capital and operating costs and
assumptions for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A:
Pond - dike height of 2 m (7 ft)
top width of 3 m (10 ft)
capacity of 750,000 cubic meters
Land - 40 hectares (100 acres)
Transverse dike - height of 461 meters (1,512 feet)
679
-------
TABLE VI11-22. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGORY: Mercury Mills Employing Flotation Process
PLANT SIZE; 159. OOP
PLANT AGE: YEARS
(under construction in 1975)
METRIC TONS (175.000 SHORT TONS) PER YEAR OF ore milled
PLANT LOCATION; Nevada
a. COSTS Of TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER!
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS (SI/METRIC TON OF PRODUCT*
COSTS ($10001 TO ATTAIN LEVEL
A
565.3
64.4
62.7
6.5
133.6
0.84
B
736.0
71.5
66.4
2.5
140.4
0.88
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
He
Ni
.
CONCENTRATION (mgl i) (ppm)
RAW
(UN-
TREATED)
250,000
0.0072
0.05
AFTER TREATMENT TO LEVEL
A
0
0
0
' B
0
0
0
C
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OP PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: TOTAL RECYCLE (ZERO DISCHARGE)
LEVEL B: IMPOUNDMENT AND EVAPORATION (ZERO DISCHARGE)
680
-------
Diversion ditching - total of 1,405 meters (4,608 feet)
Distribution system - around one pond - pipe measurina
34 cm (13.4 in., x if844 m 9
(6,048 ft)
Piping - mill to pond - flow dim (3.3 ft,/sec throuah
pipe measuring 34 cm (13.4 in., x 1000 meters
(3,280 feet,
pond to mill - flow 92m (6.6 feet,/sec through
pipe measuring 25 cm (9.8 in., x 1000 meters
(3,280 feet,
Pumps - mill to pond - slurry type, capacity of 5.260 l
(1,389 gal,/minute A
pond to mill - water type, capacity of 5,260 l
(1,389 gal,/minute
Operating-Cost Assumptions for Level A:
Power - 48 JcW (65 hp,
Capital Investment;
Facilities
Diversion ditching $ 2,320
Lagoon 149,760
Transverse dike 24,900
Facility subtotal 176,980
Contingency and contractor's fee 23.010
Total facility cost $ 199,990
Land 70,000
Equipment
Distribution system 119,860
Piping 116,000
Pumps 25.500
Equipment subtotal 261,360
Contingencity and contractors fee 33.975
Total equipment cost 295*335
Total Capital Investment j 565,325
Annual Cost;
681
-------
Amortization
Facility $ 20,370
Equipment 44,015
Total amortization $ 64,385
Operation and Maintenance (O6M)
Land 7,000
Facility repair and maintenance 5,310
Equipment repair and maintenance 7,075
Distribution system maintenance 35,960
Taxes 1,750
Insurance 5,650
Total OSM costs 62,745
Electricity 6*500
Total Annual Cost $ 133,630
Level Bj. Impoundment and Evaporation (Zero Discharge)
The facilities required for level-B treatment are
essentially the same as those required for level-A
treatment. However, a larger pond area is required. An 80-
hectare (200-acre) rectangular pond with three transverse
dikes to provide four separate ponds of 20 hectares (50
acres) each is required for impoundment and evaporation.
The equipment required includes a tailing-disposal system
(the same as that for level A), pumps, and pipes. The
capital and operating costs and assumptions for attaining
this level are shown below.
Capital-Cost Components and Assumptions for Level Bj^
Pond - dike height of 2 meters (7 ft)
top width of 3 meters (10 ft)
capacity of 1,500,000 cubic meters (396,260,000 gal)
Land - 80 hectares (200 acres)
Transverse dikes - 3, each 650 meters (2,132 feet) in length
Diversion ditching - around one length and one width, 1,970
meters (6,462 feet) in length
Distribution system - piping around one 20-hectare (50-acre)
pond; diameter of 34 cm (13.4 in.)
682
-------
and length of 1,844 m (6,048 ft)
Piping - mill to pond flow aim (3.3 ft)/sec through pipe
measuring 34 cm (13.4 in.) x 1000 meters
(3,280 feet)
Pumps - mill to pond slurry type, capacity of 5,260 1
(1,390,000 gal)/min
Operating-Cost Assumptions for Level E^
Power - 19 kw (25 hp)
Capital Investment;
Facilities
Diversion ditching $ 3,250
Lagoon 211,200
Transverse dike 105,300
Facility subtotal 319,750
Contingency and contractors fee 41,570
Total facility cost $ 361,320
Land 140,000
Equipment
Distribution system 126,750
Piping 65,000
Pumps 16.000
Equipment subtotal 207,750
Contingency and contractor's fee 27,010
Total equipment cost 234,760
Total Capital Investment $ 736,080
Annual Cost!
Amortization
Facility $ 36,800
Equipment 34,745
Total amortization $ 71,545
Operation and Maintenance (OSM)
Land ^ QQQ
Facility repair and maintenace 9'590
683
-------
Equipment repair and maintenance 4,050
Distribution system maintenance 38,025
Taxes 3,500
Insurance 7,275
Total OSM COStS 66,440
Electricity 2.500
Total Annual Cost S 140,485
Mercury Mills Employing Gravity Separation
There is only one mill in this subcategory. The discharge
of wastewater is 1,665 cubic meters (436,000 gallons) a day
during wet seasons. The mill process water is recycled.
Annual ore milled is 27,000 metric tons (30,000 short tons).
One level of technology is considered. The total costs of
implementing this level are shown in Table VIII-23.
Waste Water Treatment Control
Level A! Diversion Ditching (Zero Discharge)
Diversion ditching along one length and one width of the
present tailing pond is recommended to avoid stress in the
system due to seasonal runoff. The capital costs and
assumptions for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level Aj_
Diversion ditching - 225 meters (738 feet) a $1.65/meter
($0.50/foot)
Capital Investment:
Facilities
Diversion ditching $
Facility subtotal
Contingency and contractor's fee
Total facility cost $
684
-------
TABLE VIII-23. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEQORY! Mercury Mills Employing Gravity Separation
PLANT SIZE: 27tOOO METRIC TONS (30.000 SHORT TONS) PER YEAR OF Ore milled
PLANT APE; 4 YEARS PLANT LOCATION; California
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSIS)/METRIC TON OF PRODUCT*
COSTS ($1000) TO ATTAIN LEVEL
A
0.4
0.045
' 0.010
0.055
0.002
B
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
HP
Mi
CONCENTRATION (mo/ W (ppml
RAW
(UN-
TREATED)
154,000
0.68
0.125
AFTER TREATMENT TO LEVEL
A
o
o
n
B
C
D
E
*ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0407
LEVEL A: DIVERSION DITCHING (ZERO DISCHARGE)
685
-------
Total Capital Investment $ 420
Annual Cost;
Amortization $ 45
Operation and Maintenance (O6M)
Facility repair and maintenance
Total OSM costs
Total Annual Cost
WASTEWATER TREATMENT COSTS FOR URANIUM ORE CATEGORY
Uranium Mines
There are between 120 and 175 uranium mines in the U.S. The
annual amount of ore mined ranges from 1,800 to 504,000
metric tons (1,980 to 554,500 short tons). The daily
wastewater flow ranges from 0 to 5,000 cubic meters (0 to
1,321,000 gallons).
A hypothetical mine with an annual ore production of 280,000
metric tons (308,000 short tons) and with a daily water flow
rate of 1,900 cubic meters (500,000 gallons) was chosen as
representative.
Several levels of technology have been considered. The
total costs of implementing these levels are shown in Table
VIII-24.
Waste Water Treatment Control
Level A: Flpeculation
The necessary settling and polishing ponds are already
installed at the typical uranium mining operation. The
addition of 5 mg/1 of flocculant is required for settling of
suspended solids. The capital and operating costs and
assumptions for attaining this level are shown below.
Capital-Cost Components and Assumptions for Level A:
Flocculation -
686
-------
TABLE VIII-24. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE (Sheet 1 of 2)
suecATEGORY: Uranium Mines
PLANT SIZE: 280.000
PLANT ACE: N/A YEARS
METRIC TONS ( 308,000 SHORT TONS) PER YEAR OF_ore_jnined_
PLANT LOCATION: N/A
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($10001 TO ATTAIN LEVEL
A
16.8
2.5
11.4
11.3
25.2
0.09
B
86.8
12.9
15.2
11.5
39.6
0.14
c
228.1
33.9
(45.2)**
11.5
0.2
nil
0
240.5
35.8
(19. 9)*
11.5
27.4
0.10
E
282.6
42.1
* (2.0)*'
13.5
53.6
0.19
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
COD
As
Cd
Mo
v"
Zn
Ra 226
U
CONCENTRATION
-------
TABLE VI11-24. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE (Sheet 2 of 2)
SU8CATEGORY:
Uranium Mines
PLANT SIZE: 280, OOP
PLANT AGE: N/AyEARS
METRIC TONS ( 508,000 SHORT TONSl PER YEAR OF OT6 mined
PLANT LOCATION: N/A
I. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT*
COSTS ($10001 TO ATTAIN LEVEL
E
282.6
42.1
C2.0)"
13.5
53.6
0.19
F
294.0
43.8
2.2
16.5
62.5
0.223
G
435.3
64.8
8.9
16.5
90.2
0.32
*
298. 2
44.4
49.7
16.5
110.6
0.395
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
COD
As
Cd
Mo
V
Zn
Ra 226(dissolved)
U
CONCENTRATION (mg/£) (ppm)
RAW
(UN-
TREATED)
530
750
2
O.OS
16
10
0.5
3,200T
25
AFTER TREATMENT TO LEVEL
E
20
100
0.5
0.05
16
10
0.5
3f
2
f
20
50
0.5
0.05
16
10
0.1
3T
2
G
20
50
0.5
0.05
2.0
10
0.1
3*
2
H
20
50
0.5
0.05
2.0
5
0. 1
3f
2
•ORE MINED. TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.907
••TREATMENT RESULTS IN NET RETURN ON INVESTMENT. (REFER TO TEXT)
•VALUE IN PICOCURIESAt
LEVEL F: LEVEL E PLUS SULFIDE PRECIPITATION AND AERATION
LEVEL G: LEVEL F PLUS ION EXCHANGE
LEVEL H: LEVEL F PLUS F«SO4 COPRECIPITATION
688
-------
1 mix tank with capacity of 1,900 liters
(500 gallons)
2 mix tanks with capacity of 9,500 liters
(2,500 gallons)
2 positive-displacement pumps
Operating-Cost Assumptions for Level A:
Flocculant - 6,621 kg (7,300 Ib)/year
Operating personnel - 1 hr/day
Power - 9.7 kW (13 hp)
Capital Investment;
Equipment
Flocculation system $ 14,900
Contingency and contractor's fee 1.940
Total Capital Investment $ 16,840
Annual Cost;
Amortization $ 2,510
Operation and Maintenance (OCM)
Operating personnel $
Equipment repair and maintenance
Materials
Insurance
Total OCM costs
Electricity 11,300
Total Annual Cost $ 25,175
Level B; Level A plus Clarification
Level-B technology includes level-A technology plus clarifi-
cation. A one-hour retention time in the clarification unit
is assumed. The clarifier required has a capacity of 80
cubic meters (20,850 gallons). The capital and operating
costs and assumptions for attaining this level are shown
below.
Capital-cost Components and Assumptions for Level B;
689
-------
Clarifier - capacity of 80 cubic meters (20,850 gallons)
Operating-Cost Assumptions for Level B:
Power - 1.5 kW (2 hp)
Capital Investment;
Equipment
Clarifier $ 62,000
Contingency and contractor's fee 8,060
Total Capital Investment $ 70.060
Annual Cost;
Amortization $ 10,440
Operation and Maintenance (O8M)
Equipment repair and maintenance $ 3,100
Insurance 700
Total OSM costs 3,800
Electricity 200
Total Annual Cost $ 14,440
Level C: Level B plus Ion Exchange
The amount of resin needed is dependent upon the character-
istics of the wastewater. For this report, the amount of
resin chosen was based on actual operations.
A recovery of 13.6 kg (30 Ib) of 03O8 is made daily in the
ion-exchange unit. ~"
The capital and operating costs and assumptions for attain-
ing this level are shown below.
Capital-Cost Components and Assumptions for Level C:
Ion exchanger - capacity of 5.6 cubic meters (7.3 cubic
yards)
Operating-Cost Assumptions for Level C:
690
-------
Operating personnel -3.5 hr/day
Materials - change resins every 3 years
Product recovery - 13.6 kg (30 Ib)/day of U3O8 3 $17.60/kq
($7.99/lb)
Capital Investment;
Equipment
ion exchanger $ 125,000
Contingency and contractor's fee 16.250
Total Capital Investment $ 141,250
Annual Cost;
Amortization $ 20,975
Operation and Maintenance (OSMl
Operating personnel $ 11,025
Equipment repair and maintenance 6,250
Materials 4,670
Insurance 1,410
Total OSM costs 23,355
Total Annual Cost 44,330
Less Product Recovery 83,775
Net Annual Recovery $ 39,445
Level D: Level C plus Barium Chloride Coprecipitation
Level-D technology, compared with that of level C, requires
the addition of flocculant and barium chloride for the
precipitation of radium. The costs for this system are
based on actual operations. The costs for barium chloride
coprecipitation are shown below. Total costs for level D
are shown in Table VIII-24.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level D:
Barium chloride coprecipitation system
691
-------
Opera-ting-Cost Assumptions for Level D:
Flocculant - 6.U metric tons (7 short tons)/year
Barium chloride - 5.U metric tons (6 short tons)/year
a $805/metric ton ($73O/short ton)
Operating personnel - 2 hr/day
Capital Investment;
Equipment
Barium chloride coprecipitation system t 11,000
Contingency and contractors fee 1,430
Total Capital Investment $ 12*430
Annual cost;
Amortization J 1,850
Operation and Maintenance (OSM)
Operating personnel $ 6,300
Equipment repair and maintenance 550
Materials 18,345
Insurance 125
Total O6M costs $ 25.320
Total Annual Cost $ 27,170
Level E: Level D plus Lime Precipitation
The required settling ponds are currently available for
precipitation. The addition of 0.9 kg of hydrated lime per
3.785 cubic meters (2 lb/1000 gal) of wastewater is consid-
ered sufficient for precipitation of heavy metals. The
total costs for implementing level-E technology are shown in
Table VIII-2U.
The incremental capital and operating costs and assumptions
for the lime precipitation necessary to attain this level
are shown below.
Capital-Cost Components and Assumptions for Level E:
Lime precipitation system
692
-------
Operating-Cost Assumptions for Level E:
Lime - 160 metric tons (175 short tons)/year
Operating personnel - 3 hr/day
Power - 14.9 kw (20 hp)
Capital Investment;
Equipment
Lime precipitation system
Contingency and contractor's fee
Total Capital Investment
Annual Cost;
Amortization $ 6,27 5
Operation and Maintenance (OSM)
Operating personnel $ 9,450
Equipment repair and maintenance 1,865
Materials 6,125
Insurance 420
Total OGM costs $ 17,860
Electricity $ 2.000
Total Annual Cost $ 26,135
Level F: Level E plus Sulfide Precipitation and Aeration
To achieve level F, the addition of 3 mg/1 of sodium sulfide
and aeration to lower COD levels would be necessary. The
total costs for implementing level-F technology are shown in
Table VIII-24.
The incremental capital and operating costs and assumptions
for attaining this level via sulfide precipitation and aera-
tion are shown below.
Capital-Cost Components and Assumptions for Level P;
Sulfide precipitation system
693
-------
Aeration - 30 kg (66 Ib) of oxygen/hour
Operating-Cost Assumptions for Level _F:
Sodium sulfide - 1,985 kg («,375 Ib)/year
Power - 22.U kW (30 hp)
Operating personnel - 1 hr/day
Capital Investment;
Equipment
Sulfide precipitation unit $ 100
Aeration equipment 10,000
Equipment subtotal 10,100
Contingency and contractor's fee 1*315
Total Capital Investment $ 11,115
Annual Cost:
Amortization $ 1,700
Operation and Maintenance (OSM)
Operating personnel
Equipment repair and maintenance
Materials
Insurance
Total OSM costs
Electricity
Total Annual Cost
Level G: Level F plus Ion Exchange
For further removal and recovery of molybdenum, another ion-
exchange unit would be necessary. Approximately the same
amount of Mo is recovered as uranium. The incremental costs
for this system are the same as for level C. However, the
value of the recovered Mo differs. The incremental capital
and operating costs and assumptions for attaining this level
are shown below.
Capital-Cost Components and Assumptions for Level G:
694
-------
Ion exchanger - capacity of 5.6 cubic meters (7.3 cubic
yards)
Operating-cost Assumptions for Level G:
Operating personnel - 3.5 hr/day
Material - change resins every 3 years
Product recovery - 4.0 kg (9 Ib)/day of Mo
9 $3.50/kg ($1.59/lb)
Capital Investment:
Equipment
Ion exchanger $ 125,000
Contingency and contractor's fee 16,250
Total Capital Investment $ 141,250
Annual Cost;
Amortization « 20,975
Operation and Maintenance (OEM)
Operating personnel $ 11,025
Equipment repair and maintenance 6,250
Materials 4,670
Insurance 1*410
Total O5M costs $ 23,355
Total annual cost 44,330
Less product recovery 4,900
Total Annual Cost « 39,430
Level H: Level F plus Ferrous Sulfate Coprecipitation
Ferrous sulfate is injected for the coprecipitation
of vanadium and molybdenum.
Capital-Cost Assumptions for Level H;
FeSO4_ injector - Screw-type feeder
Operating-Cost Assumptions for Level H;
695
-------
Material:
FeSO4_ - 1,035 metric tons (1,139 short tons) per year
Operating Personnel - 2 hr/day
Power - 0.75 kW (1hp)
Capital Investment
Eguijome_nt
FeSO4_ system $ 3,750
Contingency and contractors fee 490
Total Capital Investment $ 4,240
Annual Cost
Amortization $ 630
Operation and Maintenance fOSM)
Operating personnel $ 6,570
Equipment repair and maintenance 190
Materials 40,685
Insurance 40
Total OSM 47,485
Electricity
Total Annual Cost $48,210
O rani urn Mills Using Acid or Alkaline Leaching
There are 20 mills in this subcategory. The annual amount
of ore milled ranges from 143,640 to 2,295,000 metric tons
(158,000 to 2,524,500 short tons). The daily wastewater
flow ranges from 865 to 10,945 cubic meters (228,500 to
2,900,000 gallons). There are two operations in this
subcategory that are known to be discharging (one acid and
one alkaline leach). All others are at zero discharge.
The typical mill selected for costing has a capacity for
handling 1,500 metric tons (1,650 short tons) of ore daily.
The wastewater flow is 1.25 m3 per metric ton of ore milled
(330 gallons/short ton).
Four levels of technology are considered. The costs are
shown in Table VIII-25.
Wastewater Treatment and Control
696
-------
TABLE VI11-25. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
Leaching
SUBCATEOORY: Uranium Mills Using Acid, Alkaline, or Acid/Alkaline
PLANT SIZE; 547,500 METRIC TONS (602,250 SHQRT TONS) PER YEAR QF°re milled
PLANT LOCATION; Western U.S.
PLANT AGE:
YEARS
•. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY*11
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF. PRODUCT* (SI
COSTS ($1000) TO ATTAIN LEVEL
A
93.4
13.9
173.7
4.5
192,1
0.35
B
170.0
24.4
184.3
16.3
225.0
0.41
c
176.7
25.4
231.4
16.4
273.2
0.50
o
503.2
72.2
391.9
102.7
566.8
1.04
E
1275.0
111.5
155.7
4.8
272.0
0.50
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
COD
Ammonia
As
Mo
V
Zn
Ra 226 (diss)'
Ra 226 (total)*
CONCENTRATION (mg/X)
RAW
(UN-
TREATED)
500,000
1,000
1,400
2.5
16
120
3
5-500
15-500
AFTER TREATMENT TO LEVEL
A
20
1,000
1,400
0.5
16
120
0.3
3
10
a
20
500
100
0.5
16
120
0.3
3
10
c
20
500
100
< 0.5
2
-------
Level A; Lime Precipitation
Hydrated lime is added at the main tailings pond to create
alkaline conditions for heavy metal removal and
neutralization of acidity. Hydrated lime is added to the
tailings pond decant to effect precipitation of heavy metals
by raising the pH from approximately neutral to pH 9. A
barium chloride treatment system for removal of radium 226
is assumed to be already in operation at the discharging
mills.
Capital-Cost Components and Assumptions for Level A:
Lime precipitation unit- One hydrated lime system is
employed.
Lime slurry is pumped to
tailings pond decant.
Operating-Cost Assumptions for Level A:
Material: Hydrated lime - 4,125 metric tons
(4,538 short tons) per year. Operating
personnel - 3 hr/day.
Power - 34.3 kW (46 hp)
Capital Investment:
Equipment
Lime precipitation system $77,050
Pumps and piping 5,600
Contingency and contractors fee 10,745
Total Capital Investment $93,395
Annual Cost;
Amortization $ 13,915
Operation and Maintenance (O6M)
Operating personnel $ 9,855
Equipment repair and maintenance 4,135
Materials 158,815
Insurance 935
Total OfiM $173,740
Electricity
698
-------
Total Annual Cost $192,105
Level B: Settling and Aeration
Level B consists of settling and aeration to lower the COD level,
Capital Cost Components and Assumptions for Level B;
Settling pond - depth of 2m (7 ft)
dike top width of 3 m (10 ft)
capacity of 3,370 cubic meters
(890,400 gallons)
Aeration pond - Equipped with 8 mechanical aerators
depth of 2 m (7 ft)
dike top width of 3 m (10. ft)
capacity of 6,730 cubic meters
(1,778,100 gallons)
Land - 0.89 hectare
Operating-Cost Assumptions for Level B;
Operating personnel - 2 hr/day
Power - 91 *W (122 hp)
Capital Investment;
Facilities
Settling pond $ 5,600
Aeration pond 7,200
Contingency and contractor's fee 1,665
Total Facility Cost $ 14,465
Land S 1,560
Equipment
Aerators $ 46,355
Pumps and piping 7,215
Contingency and contractor's fee 6,965
Total equipment cost $ 60,535
Total Capital Investment $ 76,560
Annual Cost
Amortization
699
-------
Facilities $ 1,475
Equipment 9.020
Total Amortization $ 10,495
Operation and Maintenance
Land $ 155
Operating personnel 6,570
Facility repair and maintenance 385
Equipment repair and maintenance 2,680
Taxes 10
Insurance 765
Total OSM $ 10,595
Electricity $ 11r805
Total Annual Cost S 32.895
Level Cj, Addition of Ferrous Sulfate and Sulfide
Precipitation
Ferrous sulfate is injected at the mill discharge for the
coprecipitation of vanadium and molybdenum as ferric
vanadate and ferric molybdate. Sodium sulfide is added at
the settling pond to further suppress heavy metal
concentration.
Capital-Cost Components and Assumptions for Level C;
FeSO4_ injector - screw-type feeder
Na^S* precipitation system - mixing tank plus chemical
metering pump
Operating-Cost Assumptions for Level C;
Material:
FeSCM - 1,022 metric tons (1,124 short tons) per year
Na^S* - 3.65 metric tons (4 short tons) per year
Operating personnel - 2 hr/day
Power - 0.75 kw (1 hp)
Capital Investment;
Equipment
FeSO4 system $ 3,570
Na^S* system 2,430
Contingency and contractor's fee 780
700
-------
Total Capital Investment $ 6,780
Annual Cost
Amortization $ 1,010
Operation and Maintenance (OSM)
Operating personnel $ 6,570
Equipment repair and maintenance 300
Materials 40,150
Insurance 70
Total OSM $ 47,090
Electricity $ 95
Total Annual Cost $ 48.195
Level D:. Ammonia Steam Stripping
Mills which use ammonia in their extraction process may be
required by state and local regulations to install ammonia
removal systems. Such regulations could apply to both
discharging and zero-discharge mills. Estimated capital and
annual costs of a system capable of treating a daily flow of
190 cubic meters (719,150 gallons) of wastewater are
summarized below. The treatment process results in the
recovery of about 1,330 metric tons (1,460 short tons) of
NH^ annually. The recovered NH3> could be used in the
extraction process and its value offset against the annual
system cost.
Capital Investment
Facilities
Concrete pits and building $ 34,000
Contingency and contractor's fee 4,420
Total facility cost $ 38,420
Land 715
Equipment
Tray tower, steam plant, other $254,285
Contingency and contractors fee 33,055
Total equipment cost $287,340
Total Capital Investment $326,475
701
-------
Annual Cost
Amortization $ 46,735
Operation and Maintenance 160,460
Energy 86,365
Total Annual Cost $293.560
Discussion
State regulations may require the installation of liners in
tailings and settling ponds in some regions. The
implementation of such regulations would force affected
mills to construct new facilities. To assess the cost
impact of such regulations, total wastewater treatment costs
have been estimated for acid and alkaline discharging and
zero-discharge mills. These total costs are presented in
Table VIII-26 and include all treatment processes applicable
at each treatment level. For example, the capital and
annual costs associated with barium chloride addition are
part of the Level-A costs in Table VIII-25. Note that the
costs of this treatment process were excluded from the
incremental costs presented in the preceding section, since
this process was assumed extant at the operating mills.
Level-A capital costs can be categorized into four groups.
The smallest capital costs, $556,000 and $592,000 are
incurred by the discharging, unlined, alkaline and acid
mills, respectively. Next in cost at $1,275,000 are zero-
discharge, unlined acid and alkaline mills. Discharging
lined acid and alkaline mills require a capital expenditure
of about $1,900,000. The capital costs for zero-discharge,
lined, acid and alkaline mills exceed $8,000,000.
The zero-discharge, unlined, acid and alkaline mills exhibit
the lowest annual cost ($272,000) and treatment cost per
metric ton of product ($0.50). Next, in order of increasing
annual costs are the discharging, unlined, acid and alkaline
mills. The zero-discharge, lined, acid and alkaline mills
incur the highest annual costs. The magnitude of these
costs is attributable mainly to the amortization costs of
pond liners.
The costs of Level-B treatment affect only the discharging
mills. The additional capital and annual costs are about
$76,000 and $32,000 for unlined mills; $111,000 and $49,000
for the lined mills.
702
-------
o
CO
TABLE VIII-26. COMPARISON OF MODEL-MILL TOTAL EFFLUENT-TREATMENT COSTS
CUMULATIVE
COSTS TO ATTAIN
1. Discharging, unlined, acid
2. Discharging, lined, acid
3. Discharging, unlinad, alkaline
4. Discharging, lined, alkaline
5. Zero-discharge, unlined, acid
or alkaline
6. Zero-discharge, lined, acid
7. Zero-discharge, lined, alkaline
•Capital and annual com .re expressed in thousand* of dollars.
Costs (in dollars) per metric ton; to obtain con per short ton. multiply each cost shown by 0.907.
-------
Level-C treatment also applies only to the discharging
mills. Level-C capital costs are small, less than $7,000.
The annual costs amount to about $48,000 and represent
primarily material costs.
Level D represents ammonia stripping and is estimated to be
required by one-half of the operating mills.
Finally, it is noted that the relative capital and annual
cost rankings of the model mills remain the same at each
treatment level.
WASTE KATES TREATMENT COSTS FOP METAL ORES, NOT ELSEWESPE
CLASSIFIED
Antimony Mines
There is only one mine in this subcategory. To date, it has
no discharge; however, this mine was started in 1970, and a
discharge may occur as . it becomes more extensively
developed.
A hypothetical discharge of 378.5 cubic meters (100,000
gallons) of wastewater daily is assumed for this operation.
The annual ore production is 10,300 metric tons (11,365
short tons).
Two levels of technology are considered. The total cost of
each level is shown in Table VIII-27.
Waste Water Treatment Control
Level A: Lime Precipitation and Settling
A simplified method of lime precipitation is considered.
The addition of 1.36 kg of hydrated lime per 3.785 cubic
meters (3 lb/1000 gallons) of wastewater is the recommended
dosage. A 15-day supply of lime slurry is drawn off as
needed, mixed with the raw wastewater for 15 minutes in a
mix tank, and discharged to a settling pond for a one-day
retention time. A secondary pond is needed for further
settling before discharge.
The capital and operating costs and assumptions for attain-
ing level A are shown below.
Capital-Cost components and Assumptions for Level A:
704
-------
TABLE VIII-27. WATER EFFLUENT TREATMENT COSTS AND RESULTING WASTE-
LOAD CHARACTERISTICS FOR TYPICAL MINE
SUBCATEQORV: Antimony Mines
PLANT SIZE: 10 » 300
PLANT AQE:N/A YEARS
METRIC TONS ( 11,365 SHORT TONS) PER YEAR OF ore mined
PLANT LOCATION; N/A
i. COSTS Of TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTSISI/METRIC TON OP PRODUCT'
A
29.9
4.2
12.9
1.1
18.2
1.77
COSTS ($1000) TO ATTAIN LEVEL
B
30.0
4.2
16.1
1.1
21.4
2.08
c
0
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
As
Fe
Sb
Zn
CONCENTRATION Img/l) (ppm)
RAW
(UN-
TREATED)
25
0.7
1.5
0.6
0.3'
AFTER TREATMENT TO LEVEL
A
20
0.5
1.0
0.5
0.2
B
20
0.5
1.0
0.5
0.2
C
D
E
*ORE MINED. TO OBTAIN COSTS/SHORT TON OP PRODUCT, MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: LIME PRECIPITATION AND SETTLING
LEVEL B: LEVEL A PLUS SULFIDE PRECIPITATION
1 HYPOTHETICAL
705
-------
2 Ponds - dike height of 2 meters (7 feet)
- top width of 3 meters (10 feet)
- capacity of 570 cubic meters (150r600 gallons)
Lime precipitation unit -
one mix tank with capacity of 8,515 liters
(2,245 gallons)
one mix tank with capacity of 4,165 liters
(1,102 gallons)
Pujip - capacity of 0.26 cubic meter (69 gallons) per
minute
Piping - mine to pond - Flow a 2 meters (6.6 feet)/
second through pipe measuring 5 cm (2 in.)
x 1000 meters (3,280 ft)
pond A to pond B - Flow a 1 meter (3.3 feet)/
second through pipe measuring 7 cm (2.75 in.)
x 100 meters (328 feet)
Land - 0.21 hectare (0.5 acre)
Operating-Cost Assumptions for Level A:
Lime - 47.25 metric tons (52.5 short tons)/year
Operating personnel - 3 hr/day
Power - 8.2 kW (11 hp)
Capital Investment:
Facilities
Lagoons f 3,200
Contingency and contractor's fee 415
Total facility cost $ 3,615
Land 350
Equipment
Lime precipitation unit 6,950
Piping 16,000
Equipment subtotal 22,950
Contingency and contractors fee 2,985
706
-------
Total equipment cost 25,935
Total Capital Investment $ 29,900
Annual Cost;
Amortization
Facility
Equipment
Total amortization
Operation and Maintenance (O&M)
Land
Operating personnel
Facility repair and maintenance
Equipment repair and maintenance
Materials
Taxes
Insurance
Total O6M costs
Electricity 1,100
Total Annual Cost $ 18f215
Level B: Level A plus Sulfide Precipitation
In addition to level-A treatment, sulfide precipitation is
recommended. Sodium sulfide is added at a rate of 1 mg/1
to the wastewater stream with the lime. Total costs for
level-B treatment are shown in Table VIII-27.
The incremental capital and operating costs (sulfide preci-
pitation only) and assumptions for attaining level B are
shown below.
Capital-Cost Components and Assumptions for Level B:
Sodium sulfide addition
Operating-Cost Assumptions for Level B:
Operating personnel - 1 hr/day
Sodium sulfide - 132 kg (292 lb)/year
707
-------
Capital Investment;
Equipment
Sulfide precipitation unit $ 100
Contingency and contractor's fee 13
Total Capital Investment S 113
Annual Cost:
Amortization * 15
Oceration and Maintenance (O&M)
Operating personnel
Equipment repair and maintenance
Materials
Total O&M costs
Total Annual Cost $ 3,200
Titanium Mines
There is one mine in this subcategory. It produces
1,180,000 metric tons (1,300,000 short tons) of ore
annually. The daily mine discharge is 2,650 cubic meters
(700,000 gallons) of wastewater. One level of technology is
considered for this subcategory. The cost of implementing
this level is shown in Table VII1-28.
Waste Water Treatment Control
Level A: Lime Neutralization and Settling
The addition of 0.9 kg of hydrated lime per 3.785 cubic
meters (2 lb/1000 gallons) of wastewater is recommended for
neutralization. The treated effluent is retained for one
day in a settling pond before discharge.
The capital and operating costs and assumptions for attain-
ing this level are shown below.
Capital-Cost Components and Assumptions for Level A:
708
-------
TABLE VIII-28. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE
8UBCATEGORY: Titanium Mines
PLANT SIZE; 1*180,000 METRIC TONS ( * » 30° > 0°0 SHORT TONS) PER YEAR QF°re mined
PLANT APE;30 YEARS PLANT LOCATION:
a. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS«)/METRIC TON OF PRODUCT-
COSTS ($10001 TO ATTAIN LEVEL
A
94.3
13.6
23.0
3.0
39.6
0.034
B
C
D
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Fe
CONCENTRATION (mg/4) (ppm)
RAW
(UN-
TREATED)
25
1.5
AFTER TREATMENT TO LEVEL
A
20
1.0
B
•
C
D
E
*ORE MINED TO OBTAIN COSTS/SHORT TON OF PRODUCT. MULTIPLY COSTS SHOWN BY 0.007
LEVEL A: LIME NEUTRALIZATION AND SETTLING
709
-------
Lime precipitation unit
Piping - Flow at 2 m (6.6 feet)/sec through pipe measur-
ing 13 cm (5.1 in.) x 1000 meters (3,280 feet)
Pond - dike height of 3 meters (10 ft)
top width of 3 meters (10 ft)
capacity of 4,000 cubic meters (1,057,000 gallons)
Land - 0.3 hectare (0.75 acre)
Operating-Coat Assumptions for Level A:
Lime - 222 metric tons (245 short tons)/year
Operating personnel - 3 hr/day
Power - 22.4 kW (30 hp)
Capital Investment;
Facilities
Lagoon $ 7,000
Contingency and contractor's fee 910
Total facility cost $ 7,910
Land 525
Equipment
Lime neutralization unit 43,000
Piping 33,000
Equipment subtotal 76,000
Contingency and contractor's fee 9,880
Total equipment cost 85,880
Total Capital Investment $ 94,315
Annual Cost;
Amortization
Facility $ 805
Equipment 12.800
Total amortization $ 13 505
Operation and Maintenance (OGM)
710
-------
Land 50
Operating personnel 9,450
Facility repair and maintenance 210
Equipment repair and maintenance 3,800
Materials 8,575
Taxes 15
Insurance 945
Total OSM costs 23,045
Electricity 3.000
Total Annual Cost $ 39,650
Titanium Mills Employing Electrostatic and/or Magnetic
Separation with Gravity and/or Flotation Process
There is only one mill in this subcategory. It mills
1,179,100 metric tons (1,300,000 short tons) annually and
has a daily water discharge of 35,770 cubic meters
(9,450,000 gallons). This mill recycles its process water;
however, there is a seasonal discharge from the tailing-pond
system. The discharge is approximately 757 cubic meters
(200,000 gallons) a day for two months of the year.
Two levels of technology are considered. The total costs of
implementing these levels are shown in Table VTII-29.
Waste Water Treatment Control
Level A: Diversion Ditching
Diversion ditching around one length and one width of the
tailing pond should help to reduce stress in the system due
to seasonal runoff. The exact length and width of the tail-
ing pond are not known. Therefore, a hypothetical length
and a hypothetical width are assumed.
4,
The capital and operating costs for attaining this level are
shown below and in Table VIII-29.
capital-Cost components and Assumptions for Level A:
Diversion ditching - 1000 meters (3,280 feet)
Capital investment;
711
-------
TABLE VIII-29. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MILL
SUBCATEGORY:
Titanium Mills Employing Electrostatic and/or Magnetic
Separation with Gravity and/or Flotation Process
PLANT SIZE =1,180,000
PLANT AGE: 30 YEARS
METRIC TONS (1,300, OOP SHORT TONS) PER YEAR OF ore milled
PLANT LOCATION: NewYork
». COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS/METRIC TON OF PRODUCT'
COSTS ($1000) TO ATTAIN LEVEL
A
1.9
0.20
0.07
0.27
0.0002
8
12.1
1.2
0.4
1.6
0.0013
c
o
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
Ni
Zn
Fe
CONCENTRATION (mg/£) Ippml
RAW
(UN-
TREATED)
26,800
0.62
1.2
143
AFTER TREATMENT TO LEVEL
A
20
0.1
0.2
0.1
B
0
0
0
0
c
D
E
ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: DIVERSION DITCHING
LEVEL B: LEVEL A PLUS HOLDING POND (ZERO DISCHARGE)
712
-------
Facilities
Diversion ditching
Contingency and contractor's fee
Total Capital Investment $ 1,965
Annual Cost:
Amortization $ 199
Operation and Maintenance (O6M)
Facility repair and maintenance $ 50
Insurance 20
Total OSM costs 70"
Total Annual Cost $ 260
Level B: Level A plus Holding Pond (Zero Discharge)
In addition to diversion ditching, a holding pond for the
excess water may be necessary. This pond is located such
that any runoff collected by the diversion ditching would
flow into it and be stored for at least five days.
Water from the holding pond could be discharged after the
suspended solids have settled. The incremental costs for
the holding pond are shown below. The total costs for
level-B treatment are shown in Table VIII-29.
Capital-Cost Components and Assumptions for Level B:
Pond - dike height of 3 meters (10 ft)
top width of 3 meters (10 ft)
capacity of 5,678 cubic meters (1,500,000 gallons)
Capital Investment;
Facilities
Lagoon $ 9,000
Contingency and contractor's fee 1,170
Total capital Investment 510,170
Annual Cost;
Amortization $ 1,035
713
-------
Operation and Maintenance (05M)
Facility repair and maintenance $ 270
Insurance 1°°
Total OEM costs 370
Total Annual Cost $ 1,405
Platinum Mine/Mills Employing Dredging
There is one known platinum mine/mill complex. The daily
discharge of wastewater is 32,702 cubic meters (8,640,000
gallons). Annual ore production is 2,267,500 metric tons
(2,500,000 short tons).
Two alternative levels of treatment are considered. The
total costs of implementing these levels are shown in Table
VIII-30.
Waste Water Treatment Control
Level A: Coagulation with Alum
It is assumed that the addition of 25 mg/1 of alum is suffi-
cient for coagulation. The necessary settling ponds have
already been constructed.
The alum feed system consists of two mixing tanks, each
having a capacity of 16.5 cubic meters (4,359 gallons), and
two positive-displacement pumps for adding the alum
solution. The alum solution is mixed and fed to the
wastewater stream at a 1-percent solution. The capital and
operating costs and assumptions for attaining this level are
shown below.
Capital-cost Components and Assumptions for Level A:
two mix tanks, each with capacity of 16.5 cubic meters
(4,359 gallons)
two positive-displacement pumps
Operating-Cost Assumptions for Level A:
Alum - 285 metric tons (315 short tons)/year
Operating personnel - 5 mixes/day a 1 hr/mix
714
-------
TABLE VI11-30. WATER EFFLUENT TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL MINE/MILL
suBCATEOORY: Platinum Mine/Mills Employing Dredging
PLANT SIZE; 2,267,500 METRIC TONS (2,500,OOP SHORT TONS) PER YEAR OP material handl ed
PLANT AGE:_^4£YEARS PLANT LOCATION; Alaska
i. COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDING ENERGY AND POWER)
ANNUAL ENERGY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS (SJ/METRIC TON OF PRODUCT*
A
18.0
2.7
35.6
1.1
39.4
0.017
COSTS ($10001 TO ATTAIN LEVEL
•
16.8
2.5
73.5
1.3
77.3
0.034
C
0
E
b. RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
TSS
CONCENTRATION (ing/ I) (ppm)
RAW
(UN-
TREATED)
80,000
AFTER TREATMENT TO LEVEL
A
30
B
30
c
D
E
*ORE MILLED. TO OBTAIN COSTS/SHORT TON OF PRODUCT (ORE MILLED), MULTIPLY COSTS SHOWN BY 0.907
LEVEL A: COAGULATION WITH ALUM
LEVEL B: FLOCCULATION
715
-------
Power - 8.2 kW (11 hp)
Capital Investment;
Equipment
Alum feed system $ 15,900
Contingency and contractors fee 2,070
Total Capital Investment . $ 17,970
Annual Cost:
Amortization $ 2,680
Operation and Maintenance (OSM)
Operating personnel $ 15,750
Equipment repair and maintenance 795
Materials 18,900
Insurance 180
Total OSM costs $ 35,625
Electricity 1,100
Total Annual Cost $ 39,405
Level B: Flpeculation
The flocculant feed system is the same as that previously
described. However, for this operation, the recommended
dosage of flocculant is 2 mg/1.
Level-B costs are shown in Table VIII-30. This level is not
an addition to level-A treatment, but an alternative for it.
The capital and operating costs and assumptions for
attaining this level are shown below.
Capital-Cost Components and Assumptions for Level B:
Flocculant feed system
Operating-Cost Assumptions for Level B:
Flocculant - 23 metric tons (25.2 short tons)/year
Total Capital Investment $ 12,430
716
-------
Power - 9.7 kW (13 hp)
Capital investment;
Flocculant feed system $ 14,900
Contingency and contractor's fee 1,940
Total Capital Investment $ 16,840
Annual Cost:
Amortization $ 2,510
Operation and Maintenance (QSM)
Operating personnel $ 22,050
Equipment repair and maintenance 845
Materials 50,400
Insurance 170
Total O6M costs $ 73,465
Electricity 1.300
Total Annual Cost $ 77,275
717
-------
NON-WATER QUALITY ASPECTS
The treatment and control technologies proposed for use by
the ore mining and dressing industry present a number of
non-water quality aspects which are discussed below.
Air and Noise Pollution
The type of equipment and processes used in water treatment
and water recycling present no air or noise pollution
problems. In general, water treatment plants are isolated
and noise which is generated by equipment reaches only those
personnel in close proximity to the plant. It should be
noted, however, that large, unstabilized tailing disposal
areas used for process wastes are often a source of air
pollution in the form of dust.
Availability of Chemicals
Although many mining operations are remotely located, water
treatment chemicals such as lime and flocculating agents are
readily available in the quantities needed. These chemicals
may require transportation over long distances, but no cases
were reported where treatment reagents were difficult to
obtain.
By-Product Recovery
By-product recovery resulting from the proposed treatment
and control technologies occurs in the uranium and
ferroalloy segments of the industry. Uranium and vanadium
are being recovered from uranium ore leaching solutions by
using an ion exchange resin, yielding cost benefits through
water treatment.
Molybdenum is recovered from wastewater on a pilot scale
basis by ion exchange in the ferroalloy segment, but by-
product recovery in other segments of the industry is either
uneconomical or technologically unfeasible at the present
time.
Ground Water Contamination
Seepage and infiltration of wastewater from impoundments
into the ground may occur if tailing ponds, settling basins
and lagoons are not properly designed. Since wastewater is
often impounded over large tracts of land, the opportunities
for infiltration of chemical and radiological pollutants
into ground water are greatly increased. Nevertheless,
718
-------
various techniques for seepage prevention are available, and
ground water contamination can be avoided in well-designed
impoundmen ts.
Land Requirements
Since most mining and milling operations employ sizable
earthen impoundments for holding water, land requirements
can become very significant. Both the iron and copper
segments of the industry typically employ large tailing
ponds, up to 1575 ha (6 sq mi) and 2100 ha (8 sq mi),
respectively. Although these ponds are generally located in
areas where land is available, other mining and milling
operations are restricted to areas where local topography
and geography severely limit the amount of suitable
impoundment sites.
Energy Requirements
The energy amounts and costs required through application of
the proposed treatment and control technologies have been
estimated in section VIII as a portion of the total cost
necessary to employ the recommended technologies.
Solid-Waste Disposal
Solid-waste disposal associated with wastewater treatment in
the ore mining and dressing industry is an increasing
problem. Wastewater treatment includes removal of certain
dissolved or suspended components from wastewater, and the
removed material must be recognized as a solid-waste
problem.
Most water-treatment-related impoundments, such as settling
basins and lagoons, collect considerable quantities of
settleable solids, and dredging is usually necessary to
facilitate continued operation of the lagoon. The dredged
solids are frequently landfilled or returned to the mines
for disposal.
Effective disposal of water-treatment-derived solids demands
that measures be taken to prevent leaching of soluble
components from the solids. Analysis of tailing-pond solids
reveals hiah concentrations of heavy-metal pollutants in all
industry segments. Acidification of tailing-pond waters
through addition of acid water from smelters, refineries,
mines and pollution-control devices may solubilize these
heavy metals. Land disposal of sludges should be planned so
719
-------
that drainage does not leach pollutants from the disposed
material.
The quantities of solid wastes associated with mining (both
low-grade, unusable ores and overburden resulting from open-
pit operations) and milling (i.e., concentrator tailings, or
gangue) are very large. Unfortunately, virtually no
statistics are available to indicate the magnitude of the
problem for the ore mining and dressing industry as a whole.
However, incomplete data recently published (October 1976)
in Reference 75 indicate trends and have been used to
prepare Table VIII-31. These 1974 data reflect the "waste
rock," "overburden," and "concentrator tailings" types of
solid wastes, which reflect the larger portion of all solid
wastes; however, they do not consider the solid wastes
(sludges, slimes, etc.) resulting from wastewater-treatment
processes which may be generated by reagent addition.
Additionally, they consider the solid wastes from only five
of the ten ore categories treated by the present document,
ignoring those of the gold; silver; aluminum (bauxite);
ferroalloy-metal; and, probably most significant of all,
iron ore categories. Nevertheless, Table VIII-31 shows that
over 770 million metric tons (over 847 million short tons)
of solid wastes, excluding wastewater-treatment wastes, were
produced in 1974 from just five of the ten metal-ore
categories. Of this waste, 48.3% was waste rock, 18% was
overburden, and 33.7% was concentrator tailings. Reference
75 predicts that, compared to 1974, these wastes will
increase 16% in 1977 and 58% in 1983.
Radioactive Materials
The uranium-ore mining and milling industry may produce
wastes which are not compatible with environmental health
and which may require additional handling safeguards, such
as stabilization of tailing-disposal areas, treatment lagoon
lining, etc. About 70% of the original activity in the ore
remains with the tailings. This provides an indefinite
source of radioactivity.. Radon-222, a radioactive gas, is
produced by the decay of radium-226. This gas diffuses
through the tailings and is released to the atmosphere. The
amount of radon diffusing into the atmosphere depends upon a
number of factors, including the radium-226 content of the
tailings, the water content of the tailings, the tailing
depth, and the tailings pile dimensions. Because of the
high radium-226 content of the tailings, the piles can be a
significant source of radon-222 for an indefinite period.
control steps such as pile stabilization to reduce wind
blowing and tailings and erosion as well as covering the
tailings with asphalt, earth or other materials can minimize
their impact as a potential source of radiation exposure.
720
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TABLE VIII 31. PRINCIPAL DRY SOLID WASTES GENERATED BY SELECTED ORE CATEGORIES IN 1974
i ANNUAL AMOUNT GENERATED. BY ORE CATEGORY. IN METRIC TONS (SHORT TONS)
COPPER
365.657.000
(403.067.000)
44.511.000
(49.065.000)
240.794,000
(265.430,000)
650,962.000
(717.562.000)
LEAD/ZINC
1.866.000
(2,057,000)
0
12.430.000
(13,702.000)
14,296,000
(15.759,000)
MERCURY*
908.000
(1.001,000)
487.000
(537.000)
16.000
(18,000)
1.411.000
(1.556.000)
URANIUM/RADIUM/
VANADIUM
2.268.000
(2.500,000)
94,497,000
(104,165.000)
6,083,000
(6.705.000)
102.848,000
(113,370,000)
ORES. NOT ELSEWHERE
CLASSIFIED*
1.051,000
(1.159,000)
0
318.000
(351.000)
1,369,000
(1.386,000)
TOTALS
371,750,000
(407.784.000)
139.495,000
(153.767.000)
259,641,000
(286,206,000)
770,886,000
(847.757.000)
'Excludes production (unavailable) for operations closed in 1974.
^Excludes production (unavailable) for platinum operation.
"Excludes sludges, slimes, dusts, and all other wastes resulting from wastewater-treatment or air-emission treatment processes.
Based on Reference 75.
-------
SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE, GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which must be achieved by
July 1, 1977 are based on the degree of effluent reduction
attainable through the application of the best practicable
control technology currently available. For the ore mining
and dressing industry, this level of technology is based on
the average of the best existing performance by facilities
of various sizes, ages, and processes within each of the
industry's subcategories. In Section IV, the ore mining and
dressing industry was initially divided into ten major
categories. Several of these major categories have been
further subcategorized, and, for reasons explained in
section IV, each subcategory will be treated separately for
the recommendation of effluent limitation guidelines and
standards of performance. As also explained in Section IV,
the subcategories presented in this section will be
consolidated, where possible, in the regulations derived
from this development document.
Best practicable control technology currently available
emphasizes treatment facilities at the end of a manufact-
uring process but also includes the control technology
within the process itself when it is considered to be normal
practice within an industry. Examples of waste management
techniques which are considered normal practice within these
industries are:
(a) manufacturing process controls;
(b) recycle and alternative uses of water; and
(c) recovery and reuse of some wastewater constituents.
Consideration was also given to:
(a) the total cost of application of technology in
relation to the effluent reduction benefits to be
achieved from such application;
(b) the size and age of equipment and facilities
involved;
tc\ the process employed;
fd the engineering aspects of the application of
various types of control techniques;
fel process changes; and
(f) nonwater-guality environmental impact (including
energy requirements).
723
-------
It was determined that the quantity of mine water discharged
(and consequently mass waste loadings) was dependent upon
many factors beyond the control of the mine operator and
unrelated or only indirectly related to mine production;
therefore, effluent limitations based on concentrations only
(with the exception of pH units) are recommended for all
mining subcategories.
The quantity of mill process water used (and mill process
waste water discharged) within a subcategory is based
primarily upon the mineralogy of the ore being processed
which affects the fineness of grind required to liberate the
metal values and the processes required to concentrate the
metal values. Because of the variables within a subcategory
affecting the quantity of mill process wastewater
discharged, a relationship between production and discharge
(flow or mass waste loadings) could not be developed;
effluent limitations based on concentrations only (with the
exception of pH units) are recommended for all milling
subcategories.
It was also determined that for a number of milling
subcategories, BPCTCA, BATEA and NSPS were no discharge of
wastewater pollutants to navigable waters. This limitation
was not intended to prohibit a facility to discharge
wastewater to an available treatment system which might be
present in a combined mine and mill complex.
To preclude a facility from treating only a portion of the
mine water in a combined system so that the requirement for
recycle of mill process water can be circumvented, or by
using a good quality mine water for dilution to avoid both
recycle and treatment of mill process water, the following
criteria should be applied to a combined treatment system:
(a) If both the mine and the mill are allowed a discharge of
pollutants, the quantity or quality of each pollutant or
pollutant property in the combined discharge that is
subject to effluent limitations should not exceed the
quantity or quality of each pollutant or pollutant
property that would have been discharged had each waste
stream been treated separately.
(b) If the mill is allowed no discharge of pollutants, the
following conditions should be met:
(1) a reduction in pollutants attributable to mine
water should be shown,
724
-------
(2) all of the mine water should be treated in the
combined system,
(3) the discharge flow should not exceed the flow from
the mine minus any make-up water used in the mill,
and,
(U) the quantity or quality of each pollutant or
pollutant property in the combined discharge that
is subject to effluent limitations should not
exceed the quantity or quality of each pollutant or
pollutant property tha^: would have been discharged
had each stream been treated separately.
No discharge of wastewater pollutants from a number of ore
dressing facilities can be realized in those areas where
rainfall does not exceed evaporation. In areas where the
annual rainfall exceeds evaporation (as defined by the
National Weather service for the location of the facility).
It is recommended that a volume of water equivalent to the
difference between annual rainfall and annual evaporation on
the tailings pond be allowed to be discharged subject to the
recommended effluent limitations for the combined mine and
mill discharges.
In the event that waste streams from various sources in
addition to mines and mills (such as smelters, acid plants,
etc.) are combined for treatment and discharge, the quantity
or quality of each pollutant or pollutant property in the
combined discharge that is subject to limitations (set forth
in this document or in other documents) should not exceed
the quantity or quality of each pollutant or pollutant
property that would have been discharged had each waste
stream been treated separately.
The following is a discussion of the best practicable con-
trol technology currently available for each of the subcate-
gories, and the proposed limitations on the pollutants in
their effluents.
GENERAL WATER GUIDELINES
Process water
Process water is defined as any water used in the mill or in
the ancillary operations required for beneficiating the ore
and contacting the ore, processing chemicals, intermediate
products, byproducts, or products of a process, including
contact cooling water. All process water effluents are
725
-------
limited to the pH range of 6.0 to 9.0 unless otherwise
specified.
Mine Drainage/Mine Water
Mine drainage/mine water is defined as any water drained,
pumped or siphoned from an ore mine.
Cooling Water
In the ore mining and dressing industry, cooling and process
waters are sometimes mixed prior to treatment and discharge.
In other situations, cooling water is discharged separately.
Based on the application of best practicable control
•technology currently available, the recommendations for the
discharge of such cooling water are as follows:
An allowed discharge of all non-contact cooling water pro-
vided that the following conditions are met:
(a) Thermal pollution be in accordance with standards
to be set by EPA policies. Excessive thermal rise
in once-through non-contact cooling water in the
ore mining and dressing industry has not been a
significant problem.
(b) All non-contact cooling waters be monitored to
detect leaks of pollutants from the process.
Provisions should be made for treatment to the
standards established for process wastewater
discharges prior to release in the event of such
leaks.
(c) No untreated process waters be added to the cooling
waters prior to discharge.
The above non-contact cooling water recommendations should
be considered as interim, since this type of water plus
blowdowns from water treatment, boilers, and cooling towers
will be regulated by EPA at a later date as a separate
category.
storm-Water Runoff
Storm water runoff may present pollution control problems
whenever the runoff passes over an area disturbed by the ore
mining operation or the ore dressing operation, where there
are stock piles of ore to be processed or where waste
materials are stored.
726
-------
Facilities should be designed to treat or contain this
runoff, however, regardless of the size of the treatment
facility, there are natural occurrences which might result
in the system being overloaded with the resultant discharge
violating the effluent limitations set forth in this
section. To provide guidance to be used in the design of a
treatment system and to avoid the legal problems that might
result if an unauthorized discharge occurs, the following
provisions are recommended:
Any untreated overflow which is discharged from
facilities designed, constructed and operated to contain
all process generated wastewater and the surface runoff
to the treatment facility, resulting from a ten-year,
24-hour precipitation event and which occurs during or
directly as a result of a precipitation event shall not
be subject to the limitations set forth in this section.
The term "ten-year, 24-hour precipitation event" means the
maximum 24-hour precipitation event with a probable
reoccurrence of once in 10 years as defined by the National
Weather Service and Technical Paper No. 40r "Rainfall
Frequency Atlas of the O.S.,: May 1961 and subsequent
amendments or equivalent regional or rainfall probability
information developed therefrom. It is intended that when
subsequent events occur, each of which results in less
precipitation than would occur during a "ten-year, 24-hour
precipitation event", that result in an equivalent amount of
runoff, the same provisions will apply.
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE BY
ORE CATEGORY AND SUBCATEGORY
Category: Iron Ores
Subcateqory: iron-ore Mines
This subcategory includes mines operated to obtain iron ore,
regardless of the type of ore or its mode of occurrence.
The limitations proposed here apply to the discharge and
treatment of mine waters.
Identification of BPCTCA. Best practicable control
technology currently available (BPCTCA) for the control of
wastewater from the mining of iron ore is settling ponds
with coagulation/ flocculation systems. At selected
locations, it may be possible to employ settling ponds alone
to meet the effluent limitations specified herein. For acid
mine discharge, lime-neutralization technology is well-
727
-------
understood and is generally applied in other mining
industries. Adjustment of wastewater pH prior to discharge
may be necessary.
To implement this technology for use at facilities not
already employing the recommended treatment techniques,
settling impoundments with dispersal systems available for
delivery of flocculating agents will need to be constructed.
Rationale for selection. At least five iron-ore mines are
known to be currently employing settling impoundments for
treatment of mine wastewater. Suspended-solid removal is
enhanced by coagulation/flocculation systems, as
demonstrated at one mill tailing-impoundment system.
Levels of Effluent Reduction Attainable. The levels of
effluent parameters in wastewaters attainable, using the
above technology, are summarized in Table IX-1.
Subcategorv; Iron Ore Mills Employing Physical and Chemical
Separation and Mills Using Only Physical separation
(Magnetic and Non-Magnetic)
This subcategory contains iron-ore milling operations that
employ chemical and physical methods, and operations which
employ only physical methods to beneficiate iron ore. Mine
waters used in milling processes, or mine waters discharged
to mill treatment facilities, are subject to the limitations
proposed below.
Identification of BPCTCA. Best practicable control
technology currently available for the control of wastewater
from the milling of iron ore in this subcategory is the use
of tailing ponds with coagulation/flocculation systems.
Adjustment of wastewater pH prior to discharge may be
necessary.
Rationale for Selection. Every known iron-ore
beneficiation facility in this subcategory currently employs
tailing-pond impoundment treatment facilities. The use and
efficiency of flocculating agents have been demonstrated at
one milling tailing-impoundment system.
Effluent reduction attainable through the use of the above
technology are summarized in Table IX-2.
728
-------
TABLE IX-1. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-IRON-ORE MINES
PARAMETER
pH
TSS
Dissolved Fe
CONCENTRATION (mg/2) IN EFFLUENT
30-day average
6* to 9*
20
1.0
24-hour maximum
6« to 9"
30
2.0
* Value in pH units
729
-------
TABLE IX-2. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-IRON-ORE MILLS EMPLOYING
PHYSICAL METHODS AND CHEMICAL SEPARATION AND
ONLY PHYSICAL SEPARATION
PARAMETER
PH
TSS
Dissolved Fe
CONCENTRATION img/i)
IN EFFLUENT
30-day average
6" to 9*
20
1.0
24-hour maximum
6« to 9»
30
2.0
•Value in pH units
730
-------
Subcategory; Iron Ore Mills Employing Magnetic and Physical
Separation fMesapi Range).
This subcategory includes milling operations employing
magnetic and physical separation.
Identification of BPCTCA. The best practicable control
technology currently available for the control of wastewater
from this subcategory is no discharge of wastewater.
Rationale for Selection. To implement this technology, no
additional technology is needed, because most mills
operating in this subcategory are currently attaining zero
discharge by the use of large tailing pdhds for effective
settling of suspended solids prior to reuse and recycle of
water back to the mill for processing. The use of
clarifiers and thickeners to reduce the volume of water
discharged to the tailing pond, and to supply water for
recycle back to the milling operation, can reduce costs
incurred in pumping, as well as pipe size and energy
requirements, for implementation of this technology.
Levels of Effluent Reduction Attainable. Zero discharge of
pollutants can be attained by use of the above technology.
Category; Copper Ores
Subcategorv; Copper-Ore Mines
This subcategory includes operations obtaining copper ore
from open-pit, underground, and overburden or ore stripping
operations.
Identification of BPCTCA. The best practicable Control
technologycurrently available for the discharge of
wastewater from the mining of copper ores is the use of lime
precipitation and settling or clarification with pH
adjustment prior to discharge, if necessary. ^This may
include (1) combination of mine water with limed mill tails
prior to settling (2) addition of lime to mine water
directly or to mine water and mill water tailing pond
effluent, with subsequent settling or clarification.
Implementation of this technology can be enhanced by reduc-
tion or elimination of discharge through the application of
one or more of several techniques: (1) Reuse of water in
other operations, such as leaching or milling; (2) Control
of mine-water drainage by modification of mining techniques,
and (3) use of solar radiation to evaporate excess water.
731
-------
Rationale for Selection. Six primary copper mines discharge
mine water to surface waters. Three of these operations
treat the water by lime precipitation and settling before
its discharge.
Levels of Effluent Reduction Attainable. The levels of
effluent parameters in wastewaters attainable using the
above technology are presented in Table IX-3.
Subcateaorv; Copper Mines Employing Hvdrometalluraical
Processes
This subcategory includes mining operations employing dump,
heap, or in-situ leach processes for the extraction of
copper from ores 6V ore waste materials.
Identification of BPCTCA. The best practicable control
technology currently available in this subcategory is no
discharge of hydrometallurgical process wastewater.
To achieve this limitation, reuse, recycle, and consumption
of water by evaporation may be employed, resulting in no
discharge of water:
Leach Solution Within the Dump/Ore Bed; Dams, ditches,
and collection ponds are needed to enable the acid-leach
solution to be recovered and fully contained.
Barren Leach Solution; Barren, or used, acid solutions
should be retained in holding ponds and recycled to the
waste ore body for reuse.
Leach Solution Bleed; The use of concrete holding ponds
for precipitation and settling of dissolved solids prior
to evaporation or recycling of water is necessary to
achieve no discharge of these solutions.
Rationale for Selection. All operations surveyed currently
practice recycle and achieve zero discharge of process
water.
Levels of Effluent Reduction Attainable. Zero discharge is
attainable for solutions resulting from the operations of
this subcategory.
732
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TABLE IX-3. PARAMETERS SELECTED AND EFFLUINT
LIMITATIONS RECOMMENDED
BPCTCA-COPPER MINES
PARAMETERS
pH
TSS
Cu
Pb
Hg
Zn
CONCENTRATION WJJ
IN EFFLUENT
30-day average
6* to 9*
20
0.15
0.3
0.001
0.75
24-hour MKlNMMI
6Mor»
30
an
0.1
0.001
1.1
•Value in pH units
733
-------
subcategory; Copper Mills Employing Vat-Leaching Process
This subcategory includes those operations employing the
vat-leach method of copper extraction from ores.
identification of BPCTCA. The best practicable control
technology currently available for this subcategory is no
discharge of process wastewater.
To achieve this limitation, reuse, recycle, and consumption
of process water by evaporation may be implemented. The
total containment of vat-leach solutions in tanks or vats,
with total recycle to the process, is necessary to implemsr.--
the above control technology.
Rationale for Selection. Zero discharge of vat-leach barren
solution is currently practiced at all facilities. Of the
four operations examined, three recycle all solutions, and
one reuses the acidic process water in the production of
acid from smelter gases containing sulfur dioxide.
Levels of Effluent Reduction Attainable. Zero discharge of
process wastewater is attainable through the use of the
above control technology.
sabcategorv: Copper Mills Employing Froth Flotation
This subcategory includes those copper milling operations
which employ the froth-flotation process.
identification of BPCTCA. The best practicable control and
treatmenttechnology currently practiced within this
subcategory is lime precipitation and settling, coupled with
at least partial recycle of process wastewater. Adjustment
of wastewater pH prior to discharge may be necessary.
Rationale for Selection. Within this subcategory, there
are a number of major copper mills currently practicing
recycle of zero to 90 percent of the process-water volume.
Two of these operations treat their process wastewater with
additional lime prior to settling in a tailing impoundment.
Levels of Effluent Reduction Attainable. The levels of
concentration and waste loading attainable by implementation
of the technology recommended above are presented in Table
IX-4.
734
-------
TABLE IX-4. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS RECOMMENDED
FOR BPCTCA-COPPER MILLS USING FROTH FLOTATION
PARAMETER
PH
TSS
CN
Cd
Cu
Hg
Pb
Zn
CONCENTRATION (mg/£)
IN EFFLUENT
30-day average
6* to 9*
20
0.1
0.05
0.15
0.001
0.3
0.5
24-hour maximum
6» to 9*
30
0.2
0.1
0.30
0.002
0.6
1.0
•Value in pH units
735
-------
Category; Lead and Zinc ores
Subcategory; Lead ami Zinc Mines
This aubcategory includes mines operated for the recovery of
lead and cine ores.
Identification oj£ BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of line precipitation in combination with a settling or
sedimentation pond. An alternative technology which may be
employed is the use of high-density sludge neutralization
process with a clarifier. Retention time must be adequate
to meet or exceed the TSS limitation. Adjustment of
wastewater pH prior to discharge may be necessary.
Rationale for Selection. The levels proposed for this sub-
category are based on application of this technology at one
zinc/copper mining operation, as well as on extensive
application of this treatment at lead/zinc/copper mines in
Canada, both at full-scale operations and in pilot-
evaluation facilities (References 69, 71, and 76).
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable in this subcategory through
the application of the above technology are presented in
Table IX-5.
$ubcateaoryt Lead and zinc Kills
This subeategory includes all mills operated for the
recovery of lead or zinc concentrates. All current
operation^ in this aubcategory employ the process of froth
flotation for the beneficiation of ores.
Identification £f_ BPCTCA. The best practicable control
technology currently available for this subcategory is a
settling- or •edimentat ion- pond system with a primary
tailing pond and a secondary settling or "polishing" pond.
pH adjustment of the wastewater may be necessary prior to
discharge. The ase of cyanide removal technology
(ozonation, alkaline chlorination, peroxide addition) may be
necessary during six to eight months of the year at one
facility in this subcategory.
Rationale j&£ Selection- Currently, approximately 20
percent (at least six of the operations surveyed) have
implemented the above technology.
736
-------
TABLE IX-5. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-LEAD AND ZINC MINES
PARAMETER
pH
TSS
Cu
Hg
Pta
Zn
CONCENTRATION (mg/H)
IN EFFLUENT
30-day average
6" to 9«
20
0.15
0.001
0.3
0.75
24-hour maximum
6* to 9*
30
0.30
0.002
0.6
1.5
•Value in pH unit*
737
-------
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable by application of the above
technology are presented in Table IX-6.
Category; Gold Ores
Subcateqory; Gold Mines
This subcategory includes mines operated for the recovery of
gold ores by open-pit or underground methods. Discharge of
mine wastewater into mill waste-treatment systems, or reuse
of mine water in the milling process, is acceptable provided
that effluent limitations for the mill subcategory are met,
and provided that unfavorable water balances affecting mill
waste-treatment systems do not result.
Identification of BPCTCA. The best practicable control
technology currently available for the discharge of
wastewater resulting from the mining of gold ores is the use
of lime precipitation methods in conjunction with settling-
pond removal of suspended solids and precipitates.
Adjustment of wastewater pH prior to discharge may be
necessary. Settling of suspended solids may be performed
either in settling impoundments or by the use of mechanical
clarification equipment to meet the levels of effluent
reduction specified here.
Rationale for Selection. Treatment of mine wastewater as
currently practiced by these operations varies from non-
existent to the use of settling impoundments. Because the
level of treatment which results is uniformly inadequate,
the well demonstrated technology of chemical precipitation
is specified because of its demonstrated use and efficiency
of treatment attained in other categories of the ore mining
and dressing industry.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable through the use of the above
technology are presented in Table IX-7.
Subcateqory; Gold Mills or Mine/Mills Employing jCvanidation
This subcategory includes operations obtaining gold by the
cyanidation process of extraction from gold ores.
Identification of BPCTCA. The best practicable control
technology currently available in this subcategory is no
discharge of process wastewater.
738
-------
TABLE IX-6. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-LEAD AND/OR ZINC MILLS
PARAMETER
pH
TSS
Cyanide
Cd
Cu
Hg
Pb
Zn
CONCENTRATION (mg/i)
IN EFFLUENT
30-day average
6" to 9* .
20
0.1
0.05
0.15
0.001
0.3
0.5
24-hour maximum
6* to 9*
30
0.2
0.1
0.30
0.002
0.6
1.0
•Value in pH units
739
-------
TABLE IX-7. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-GOLD MINES
PARAMETER
PH
TSS
Cu
Hg
Pb
Zn
CONCENTRATION (mg/Jl)
IN EFFLUENT
30-day average
6* to 9*
20
0.15
0.001
0.3
0.75
--•
24-hour maximum
6- to 9*
30
0.30
0.002
0.6
1.5
•Value in pH units
74Q
-------
Implementation of this control technology may be achieved in
either of two ways: impoundment or complete recycle of
process wastewater. At some locations, destruction of
cyanide by alkaline chlorination (or other oxidation methods
such as ozonation or peroxide addition) may be necessary if
the presence of cyanide in recycled water adversely affects
the process.
Rationale for Selection. Of the two mills currently
employing cyanidation processing, one operation has achieved
zero discharge by impoundment and recycle of process
wastewater. An important engineering aspect of a zero-
discharge system is the design of the water-management
system. A recycle system generally involves discharge of
mill process water to a tailing pond for settling of solids
and subsequent decantation and pumping of clarified pond
water back to the mill.
A measure of control over the quality of the reclaim water
is normally maintained by the use of a two-celled pond
system. Tailings are discharged to the first pond for
settling; then, the decant from this pond is collected in
the second pond, which serves as a surge pond in the recycle
system.
Level of Effluent Reduction Attainable, zero discharge of
pollutants is attainable by implementation of the above
control technology.
Subcategory; Gold Mills Employing Amalgamation
This subcategory includes mills extracting gold by use of
the amalgamation process.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is lime
precipitation in conjunction with sedimentation or tailing
impoundment, with in-process recycle of the mercury reagent
in the amalgamation process. Adjustment of the pH of waste
waters prior to discharge may be necessary.
Rationale for selection. Currently, there is one operating
facilitv employing"the amalgamation process for gold
extraction. To effect removal of heavy metals, the use of
chemical precipitation methods in conjunction with tailing
impoundment is Sell-documented and has-been demonstrated in
throrTminin and dressing industry at other locations.
741
-------
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable for this subcategory by use of
the above technology are presented in Table IX-8.
Subcategory; Gold Mills Employing Froth Flotation Process
This subcategory includes mills or mine/mill complexes oper-
ated for the beneficiation of gold ores by froth flotation.
The single operation employing this method also practices
cyanidation of tailings from the flotation circuit by agita-
tion/cyanidation.
Identification of BPCTCA. The best practicable control
technology currently available in this subcategory is the
use of lime precipitation, tailing impoundments and partial
recycle of process water to reduce discharge volume. If
cyanide is present in wastewater, alkaline chlorination for
cyanide destruction in discharge waters may be necessary.
Rationale for Selection. The single operating facility in
this subcategory currently practices impoundment during
approximately nine to ten months of the year. Reduction of
discharge volume on a seasonal basis is possible by recycle
of tailing decant water in conjunction with alkaline
chlorination to remove cyanide (which would interfere with
the flotation of the gold-bearing ore).
Levels of Effluent Reduction Attainable- The levels of
effluent reduction attainable for this subcategory by use of
the above technology are presented in Table lx-9.
subcategory; Gold Mills or Mine/Mills Employing Gravity
Separation Methods —
This subcategory includes mills or mine/mills beneficiating
gold ore by gravity-separation methods. This subcategory
also includes placer or dredge mining or concentrating
operations, as well as hydraulic-mining operations.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of settling or tailing impoundments for settling of
SSJ5S5
-------
TABLE IX-8. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-GOLD MILLS USING
AMALGAMATION PROCESS
PARAMETER
pH
TSS
Cu
Hg
Zn
CONCENTRATION (mg/&)
IN EFFLUENT
30-day average
6* to 9*
20
0.15
0.001
0.5
24-hour maximum
6» to 9»
30
0.30
0.002
1.0
'Value in pH unit*
743
-------
TABLE IX-9. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-GOLD MILLS USING
FLOTATION PROCESS
PARAMETER
PH
TSS
Cyanid«
Cd
Cu
Hg
Pb
Zn
CONCENTRATION img/i)
IN EFFLUENT
30-day average
8» to 9*
20
0.1
0.05
0.15
0.001
0.3
0.5
24-hour maximum
8* to 9*
30
0.2
0.10
0.30
0.002
0.6
1.0
•Value in pH units
744
-------
Rationale for Selection. The practice specified is the best
technology now utilized at several operations recovering
gold by gravity-separation methods. The prevailing practice.
in this industry subcategory is direct discharge of waste-
water.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable employing the above technology
are given in Table IX-10.
Subcatecrorv; Mill Operations where Gold is Recovered as
Byproduct of Base-Metal Milling Operation
This subcategory includes facilities operated primarily to
obtain concentrates of base metals (usually lead, zinc, or
copper). Gold may be obtained from the base-metal concen-
trates at a refinery or a smelter.
Identification of BPCTCA. No separate technology or limita-
tions are recommended for this subcategory. Instead, the
limitations and technology for each applicable base-metal
subcategory are recommended, because the characteristics of
the primary ore and processes employed dominate the waste-
water parameters.
Category; Silver ores
Subcatecrory; Silver Mines (Alone)
This subcategory includes facilities which are operated for
the mining of silver ores by open-pit or underground
methods. Discharge of mine waters into mill treatment
systems, or for reuse as process water, is covered in the
applicable limitation guidelines for milling subcategories.
identification of BPCTCA. The best practicable control
technology currently available for silver-mine discharges is
use of lime precipitation for heavy-metal removal in
conjunction with the use of settling pond(s) for suspended
solid removal. An alternative suspended-solid treatment is
the use of mechanical clarifiers. At selected locations, pH
adjustment of discharge waters may be necessary.
rational*' for selection. Current treatment practices in tbe
silver mining industry range from no treatment to use of
settling ponds where discharge to mill treatment systems or
use in a mill process is not practiced. Treatment practices
are considered to be uniformly inadequate for the removal of
pollutants present in silver-mine wastewater. Therefore,
745
-------
TABLE IX-10. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-GOLD MINES OR MILLS
USING GRAVITY-SEPARATION METHODS
PARAMETER
PH
Set. Solids
CONCENTRATION (m!/i)
IN EFFLUENT
30-day average
6' to 9*
24-hour maximum
6* to 9«
0.5
•Value in pH units
746
-------
lime treatment methods which have been demonstrated to be
effective in other segments of the ore mining and dressing
industry have been adopted in addition to use of settling
ponds.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable through the use of the above
technology are presented in Table IX-11.
Subcateaorv; Silver Mills Employing Froth Flotation
This subcategory includes those milling operations employing
the forth-flotation process for extraction of silver concen-
trates from silver ores.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of lime precipitation in conjunction with tailing
impoundments and partial or total recycle of process water.
pH adjustment of wastewater prior to discharge may be
necessary.
Rationale for Selection; Current treatment practices in the
silver industry is the use of settling ponds and partial or
complete recycle of process water.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable for this subcategory by use of
the above technology are presented in Table IX-12.
Subcateaorv; Mills or Mine/Mills Using Cvanidation for
Recovery of Silver
This subcategory includes those milling operations employing
the cyanidation process for recovery of silver from silver
ores. The recovery of silver by this method is usually done
in connection with gold recovery.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is
attainment of zero discharge by use of recycle or total
impoundment of process water.
To implement this technology, recycling in the process
reagent circuits may be necessary to achieve economy in
reagent use and avoid high concentrations of cyanide in
recycled process water.
7U7
-------
TABLE IX-11. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-SILVER MINES (ALONE)
PARAMETER
pH
TSS
Cu
H«
Pb
Zn
CONCENTRATION (mg/2.)
IN EFFLUENT
30-day average
6* to 9"
20
0.15
0.001
0.3
0.75
24-hour maximum
6» to 9«
30
0.30
0.002
0.6
1.6
•Value in pH units
748
-------
TABLE IX-12. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-SILVER MILLS USING
FROTH FLOTATION PROCESS
PARAMETER
PH
TSS
CM
Cd
Cu
Hg
Pb
Zn
CONCENTRATION (mg/ ^ )
IN EFFLUENT
30-day average
6 to 9"
20
0.1
0.05
0.15
0.001
0.3
0.5
24-hour maximum
6to9»
30
0.2
0.1
0.30
0.002
0.6
1.0
•Value in pH units
749
-------
Rationale for Selection. Currently, no treatment technology
is being practiced at the one known discharging milling
establishment in this subcategory. However, the attainment
of zero discharge at a cyanidation mill in the gold category
has been well-documented and demonstrated to be effective
for use in similar operations involving the cyanidation pro-
cess at silver mills. In addition, comparison of percentage
recovery for a mill employing cyanidation for gold/silver
recovery with no treatment to that of a gold mill practicing
total recycle indicates that no loss of recovery is
necessary with recycling of process water.
Levels of Effluent Reduction Attainable. Zero discharge of
pollutants to surface waters will result with employment of
the above technology.
Subcateqorv; Mines or Mines and Mills Extracting Silver b^
Dse of the Amalgamation Process
This subcategory includes milling operations engaged in the
recovery of silver by use of amalgamation of silver ores.
This process is often employed for the extraction of both
gold and silver from ores.
Identification of BPCTCA. The best practicable control
technology currently available is lime precipitation for
metal removal in conjunction with the use of settling
impoundments. To achieve reduction of mercury
concentrations in process wastewater, in-process recycling
within the mercury reagent circuit should be used. The
adjustment of pH of discharge waters may be necessary at
selected operations to achieve pH limitations.
Rationale for Selection. At present, there is one operation
utilizing amalgamation for the recovery of silver. This
operation currently employs two sedimentation ponds, but
metal removal by this method is inadequate. The use of
chemical-precipitation methods has been well-demonstrated in
the ore mining and dressing industry to be effective in
reduction of heavy metal pollutant concentrations.
Levsls of Effluent Reduction Attainable. The levels of
pollutant concentrations attainable by use of the above
methods are presented in Table IX-13.
750
-------
TABLE IX-13. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-SILVER MILLS USING
AMALGAMATION PROCESS
PARAMETER
PH
TSS
Cu
Hg
Zn
CONCENTRATION (mg/&>
IN EFFLUENT
30-day average
6" to 9*
20
0.15
0.001
0.5
24-hour maximum
6* to 9«
30
0.30
0.002
1.0
•Value in pH units
751
-------
Subcategorv; Silver Mills Using by Gravity-Separation
Methods
This subcategory includes those operations operated for the
recovery of silver by gravity-separation methods. Silver is
recovered in minor amounts as part of gold placer opera-
tions.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of settling or tailing impoundments for settling of
suspended solids. An alternative technology which may be
e«ployed is the pumping of wastewater from dredging
operations back to a tailing-disposal area for filtration
through sands and gravels. At some operations, it may be
necessary to enhance the settling of suspended solids to
meet the effluent limitations specified here.
Rationale for Selection. The use of settling impoundments
such as dredge ponds or tailing impoundments is the best
technology now utilized in connection with gravity methods
of extraction of silver in the dredges or placer mining
industry today.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable employing the above technology
are given in Table IX-14.
Subcatecrorv; Mill Operations where Silver is Recovered as
Byproduct of Base-Metal Milling operation
This subcategory includes facilities operated primarily to
obtain concentrates of base metals (usually, lead, zinc, or
copper). Silver may be obtained from the base-metal con-
centrates at a refinery or a smelter.
Identification of BPCTCA. No separate technology or limita-
tions are recommended for this subcategory. Instead, limi-
tations and technology for each applicable base-metal sub-
category are recommended, because the characteristics of the
primary ore and processes employed dominate the wastewater
parameters.
Category; Bauxite Ores
This category includes establishments engaged in the mining
of bauxite ores. No beneficiation of these ores is
currently practiced, with the exception of crushing and
752
-------
TABLE IX-14. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-SILVER MILLS USING
GRAVITY SEPARATION
PARAMETER
PH
S«t.Solidi
CONCENTRATION (ml/1)
IN EFFLUENT
30-day average
6* to 9"
24-hour maximum
6' to 9*
0.5
'Value in pH units
753
-------
grinding activities at the two currently operating sites.
No subcategories were identified in this category.
Identification of BPCTCA, The best practicable control
technology currently available for the removal of pollutants
present in mine drainage in the bauxite mining industry is
use of lime precipitation and settling. In the case of
alkaline ground-water drainage, aeration of wastewater may
be necessary to convert, iron to a form more amenable to lime
precipitation. Adjustment of the wastewater pH prior to
discharge may be necessary.
Rationale for Selection. The two currently operated
facilities are both practicing lime neutralization and/or
precipitation on most mine effluents at the present time.
The efficiency of this method of treatment has been well-
demonstrated in these operations on both full- and pilot-
scale bases.
Levels of Effluent Reduction Attainable. The concentration
levels attainable through implementation of BPCTCA are pre-
sented in Table IX-15.
Category; Ferroalloy Ores
Subcategorv; Ferroalloy Ore Mines Producing Greater Than
5,030 Metric Tons (5512 Short Tons) Per Year
This subcategory includes mines operated to obtain
ferroalloy metals and which discharge to surface waters of
the U.S., regardless of the particular ferroalloy metal
involved. The ferroalloy-metal ores covered here include
chromium, cobalt, columbium/tantalum, manganese, molybdenum,
nickel, tungsten, and vanadium (recovered alone). Vanadium
is also recovered as a byproduct of uranium mining and
milling operations.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of lime precipitation in conjunction with a settling
pond. For use of this technology, liming prior to removal
of suspended solids is desirable. The use of a mechanical
clari-flocculator or equivalent equipment is an acceptable
alternative for suspended solid removal. Adjustment of
wastewater pH prior to discharge may be necessary.
Rationale for selection . Sedimentation or settling
impoundments are widely used in the ore mining and dressing
industry for suspended-solid removal. The use of lime for
75*»
-------
TABLE IX-15. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-BAUXITE MINES
(ACID OR ALKALINE MINE DRAINAGE)
PARAMETER
PH
TSS
Al
Ft
Zn
CONCENTRATION (mg/ft)
IN EFFLUENT
30-day average
8* to 9*
20
1.0
0.5
0.1
24-hour maximum
6* to 9»
30
2.0
1.0
0.2
•Vilut in pH units
755
-------
pH adjustment and precipitation of metals is both an
effective practice and a standard, longstanding practice at
many milling establishments. Because metal removal by
settling methods alone is inadequate at most ferroalloy-ore
mines, relatively simple lime-precipitation methods are
recommended for use. Engineering difficulties may be
encountered where large mine flows coincide with limited
land availability, but the employment of mechanical
clarifying/ flocculating devices is an acceptable
alternative. At one ferroalloy mining site, a mechanical
device for settling suspended solids was used, and levels of
less than 15 mg/1 of suspended solids were attained.
Adjustment of pH to the range of 8.5 to 9, with removal of
solid precipitates, vill enable attainment of the effluent
levels recommended here.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable and the parameters selected
for control for this subcategory are presented in Table IX-
16. Note that no limitation for molybdenum is recommended
for BPCTCA, because this metal is not effectively removed by
currently available treatment. Discharge concentrations of
these metals will be minimized by sound practice (as
discussed above), and by avoiding leaching of ores exposed
for long periods to oxidizing conditions.
Subcateqory; Mills and Mines Processing Less Than 5,000
Metric Tons (5,512 Short Tons) Per Year of Ferroalloy Ores
This subcategory includes those operations processing less
than 5,000 metric tons (5,51-2 short tons) of ore per year by
methods other than ore leaching. Operations in this
subcategory are confined primarily to intermittent
operation, and beneficiation of the ores is frequently
performed by gravity methods. Tungsten-ore mines/mills are
the prime components of this subcategory.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of settling or tailing ponds in conjunction with
neutrali zation.
Rationale for Selection. Operations in this subcategory
are, in general, intermittent; economically marginal; and of
a low level of technical sophistication. Present practice
at these operations is predominantly direct discharge
without treatment. Data gathered here indicate that current
practices in this subcategory are uniformly inadequate.
Therefore, the relatively simple, well-demonstrated and
756
-------
TABLE IX-16. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-FERROALLOY-ORE MINES
(PRODUCING > 5,000 METRIC TONS (5,512 SHORT TONS)
PER YEAR
PARAMETER
pH
TSS
As
Cd
Cu
Mo
Pb
Zn
CONCENTRATION (mg/i)
IN EFFLUENT
30-day average
B* to 9*
20
0.5
0.05
0.16
t
0.3
0.5
24-hour maximum
6* to 9"
30
1.0
0.10
0.30
t
0.8
1.0
•Value in pH units
TNo limitations proposad for BPCTCA
757
-------
we 11-documented technology of tailing or •. settling
impoundment with pH control is recommended. The use of this
technology will represent a major improvement over present
practice at most operations in this subcategory.
Mine water, where available, should be used for mill feed,
and the mine and mill waters should be treated together.
Neutralization and suspended-solid removal will result in
some degree of removal of dissolved metals, in addition to
reduction of COD and other waste components, by use of this
technology, although monitoring of these parameters is not
recommended here.
Levels of Effluent Reduction Attainable. The parameters
selected and the recommended effluent levels attainable by
use of the above technology in this subcategory are
presented in Table IX-17,
Subcategory; Mills Processing More Than 5.000 Metric Tons
i ,512 Short Tons) of Ferroalloy Ores Per Year By. Physical
Methods
This subcategory includes mill or mine/mill facilities pro-
cessing more than 5,000 metric tons (5,512 short tons) of
ferroalloy ores per year by purely physical methods. These
methods include ore crushing, washing, jigging, heavy-media
and gravity separation, and magnetic and electrostatic
separation.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of process-water recycle practices in conjunction with
tailing impoundment, lime precipitation, flocculation, and
secondary settling. Adjustment of wastewater pH prior to
discharge may be necessary.
Total recycle of process water with zero discharge is a
possible viable alternative technology for many operations
of this type.
Rationale for Selection. The recommended BPCTCA technology
has been in large-scale use within the ore mining and dress-
ing industry, and its successful implementation on waste
streams is expected to pose no significant technical
problems. Treatment to BPCTCA levels is achieved at the
largest industry representative of this subcategory,
although natural alkalinity and low soluble ore contents
obviate the need for the practice of lime precipitation at
that site. Recycle of process waters is currently practiced
758
-------
TABLE IX-17. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS RECOMMENDED
FOR BPCTCA-FERROALLOY-ORE MINES AND MILLS PROCESSING LESS
THAN 5,000 METRIC TONS (5,512 SHORT TONS) PER YEAR
PARAMETER
PH
TSS
CONCENTRATION (mg/fi.)
IN EFFLUENT
30-day averaga
6* to 9»
30
24-hour maximum
6" to 9"
50
'Value in pH units
759
-------
at many sites and is limited technically only where wet
scrubbers are used for air-pollution control on ore-drying
or ore-roasting installations. In such operations,
dissolved-solid buildup in the scrubber-water circuit could
lead to decreased effectiveness in scrubbing and consequent
increased maintenance. Total recycle with no process-water
discharge reportedly will be practiced upon reopening of a
manganiferous-ore concentrator, which is expected to occur
some time during 1975.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by implementation of this technology are pre-
sented in Table IX-18.
Subcategory; Mills Processing More Than 5,000 Metric Tons
t ,512 Short Tons) of Ferroalloy Ores Per Year By Flotation
Methods
This subcategory includes mills processing more than 5,000
metric tons (5,512 short tons) of ferroalloy ores per year
by froth-flotation methods.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory includes
the use of primary settling or tailing ponds in conjunction
with lime precipitation and secondary settling.
Flocculation may be necessary at selected locations to meet
suspended-solid limitations.
Lime precipitation will not be necessary at some sites,
because their flotation circuits are maintained at alkaline
pH. Adjustment of wastewater pH prior to discharge may be
necessary.
Rationale for Selection. The recommended treatment and con-
trol technology is currently in use within the ore mining
and dressing industry, and its successful implementation for
waste streams from mills in this subcategory is expected to
pose no significant technical problems. Because of alkaline
pH at flotation mills and the use of settling ponds with
adequate retention time, levels recommended here are
currently being achieved at sites within the subcategory.
Recycle of process water is not recommended as BPCTCA for
these operations, since nonsulfide-ore flotation operations
would require extensive process development work and process
modification. In addition, no successful operations are
known at present which employ total recycle for fatty-acid
760
-------
TABLE IX-18. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA - FERROALLOY-ORE MILLS
PROCESSING MORE THAN 5,000 METRIC TONS
(5,512 SHORT TONS) PER YEAR BY PHYSICAL METHODS
PARAMETER
PH
TSS
As
Cd
Cu
Mo
Zn
CONCENTRATION
-------
flotation of scheelite, however, there is at least one
operation that employs partial recycle for fatty-acid
flotation of schelite.
Total recycle is a viable alternative technology for some
mills within the subcategory—particularly, since treatment
of smaller wastewater volumes may, in some cases, offer sub-
stantial economic advantages,
Levels of Effluent Reduction Attainable, The parameters
selected and levels of effluent reduction attainable by
implementation of BPCTCA are presented in Table IX-19.
Levels of cyanide and COD can be controlled by control of
reagent usage, and by natural aeration and degradation
during delivery of tailings to impoundment and during
retention in settling ponds.
Subcateqorv; Mills Processing Ferroalloy Ores By Leaching
Techniques
This subcategory includes mills processing ferroalloy ores
by leaching techniques (whether acid or alkaline) and
associated chemical-beneficiation techniques.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory includes
tailing-pond impoundment for primary settling, in
conjunction with lime precipitation, flocculation, secondary
settling, and segregation of wastewater streams.
The segregation of highly contaminated leaching, solvent
extraction, precipitation, and scrubber waste streams from
noncontact cooling water and uneontaminated waste streams is
currently practiced and is essential to effective removal of
metals from the wastewater. Adjustment of wastewater pH
prior to discharge may be necessary.
Rationale for Selection. The recommended BPCTCA is
currently in use within the ore mining and dressing
industry. Control and treatment technology within the
subcategory (except at one site leaching only concentrates)
is inadequate at present. This results in the discharge of
appreciable quantities of heavy metals, removable by lime
precipitation, and in excessive suspended-solid loads as
well as substantial discharges of ammonia. Since effluent
streams are currently very high in sulfates (10,000 mg/1),
application of lime precipitation will result in marginal
decreases (estimated to be 10 to 15 percent) in total
762
-------
Table IX-19. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-FERROALLOY-ORE MILLS
USING FLOTATION PROCESS
PARAMETER
PH
TSS
COD
Cyanide
As
Cd
Cu
Mo
Zn
CONCENTRATION (mg/&)
IN EFFLUENT
30-day average
6» to 9*
20
50
0.1
0.5
0.05
0.15
t
0.5
24-hour maximum
6* to 9*
30
100
0.2
1.0
0.1
0.30
t
1.0
•Value in pH units
tNo limitations proposed for BPCTCA
763
-------
dissolved solids, as well as in substantial removal of heavy
metals.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the effluent reduction attainable
by implementation of BPCTCA are presented in Table IX-20.
The limitation of Cr is not recommended using the BPCTCA.
Control technology at BPCTCA is not available. Hexavalent-
chromium removal requires chemical reduction, which will
require development work before application to mill waste
streams. Only trivalent chromium will be removed by lime
precipitation.
Total dissolved solids, although a major waste constitutent,
are not limited because practical control technology
applicable to these operations is not currently available.
Proper management of the discharge to ensure rapid mixing
and dispersal can alleviate possible problems of
stratification and formation of pockets of saline water in
the receiving waters.
•
Category; Mercury Ores
Subcateqorv; Mercury Mines
This subcategory includes all mines, whether open-pit or
underground, operated for the extraction of mercury ores.
Identification of BPCTCA. The best practicable control
technology currently available is use of lime precipitation
in conjunction with settling impoundments.
Chemical-precipitation methods for heavy-metal removal may
include lime- or sulfide-precipitation methods. Mechanical
clarifiers are an acceptable alternative method for
suspended solid removal. Adjustment of the pH to acceptable
levels may be necessary at some locations prior to
discharge.
Rationale for Selection. The use of settling impoundments
has been demonstrated to be effective in removal of
suspended solids at a large number of locations. Chemical-
precipitation methods are necessary to reduce heavy-metal
levels because present treatment at most locations, if any
is used, is inadequate. The use of lime-precipitation
methods with effective pH control is a demonstrated and
effective means of reducing heavy-metal concentrations. The
technology selected for control of the pollutant parameters
764
-------
TABLE IX-20. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-FERROALLOY-ORE MILLS
USING LEACHING PROCESS
PARAMETER
pH
TSS
Ammonia
At
Cd
Cr
Cu
Zn
CONCENTRATION (mg/J)
IN EFFLUENT
30-day average
6* to 9*
20
1200
0.5
0.05
t
0.15
0.5
24-hour maximum
6« to 9*
30
2400
1.0
0.1
t
0.30
1.0
•Valut in pH units
*No limitations proposed for BPCTCA
765
-------
named will also have the additional benefit of reducing
other heavy metals as well.
Levels of Effluent Reduction Attainable. The parameters
selected and the levels of effluent reduction attainable are
presented in Table IX-21.
Subcategory: Mercury Mills or Mine/Mills Employing Gravity
Separation Methods
This subcategory includes those mills processing mercury
ores by gravity-separation methods. At present, there is
one known operation employing this method.
Identification of BPCTCA. The best practicable control
technology currently available is zero discharge by recycle
of process water or total impoundment.
Rationale for Selection. The only operation using these
methods is currently attaining zero discharge by impoundment
and recycle of process water back to the process after tail-
ing-pond treatment. A secondary pond is maintained to
impound overflow should unusual conditions prevail, and to
collect any seepage through the tailing impoundment. This
water, if any, is pumped back to the primary tailing pond.
Levels of Effluent Reduction Attainable. Zero discharge of
pollutants will result from implementation of BPCTCA.
Subcategorv; Mercury Mills or Mine/Mills Using Flotation
Process
This category includes those operations beneficiating
mercury ores by the froth-flotation process.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is zero
discharge by the use of total recycle and complete
impoundment of process wastewater.
Rationale for Selection. The only known facility in this
subcategory is designed to attain zero discharge by recycle
and impoundment of process water. If the treatment system
to be used is not found adequate to handle the total
wastewater volume, provisions have already been made for
construction to double the present impoundment volume and
take advantage of evaporative losses.
766
-------
TABLE IX-21. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-MERCURY MINES
PARAMETER
PH
TSS
Hg
Ni
CONCENTRATION
-------
Levels of Effluent Reduction Attainable, The level of
effluent reduction attainable by implementation of BPCTCA is
zero discharge of wastewater to surface waters of the U.S.
subcateaorv; Mills Recovering Mercury as a Byproduct of
Base- or Precious-Metal Concentrates
This subcategory includes operations where mercury is
obtained as a byproduct of base- or precious-metal
concentrates. The recovery of mercury takes place at a
refinery or smelters.
Identification of BPTCA. No separate limitations or tech-
nology are proposed. The waste treatment technology and
effluent limitations for the appropriate subcategory of
baseor precious-metal mills are applicable to this
subcategory.
Category; Uranium, Radium, and Vanadium ores
This category includes mines and mills operated for the
extraction or concentration of uranium, radium, and vanadium
ores (Vanadium produced as a byproduct from uranium ores).
Primary vanadium production is covered, for purposes of this
report, under Ferroalloy Ores. It is noted that the suite
of treatments used at mines recovering values from igneous
rocks differ from but overlaps that used at mines in
sedimentary deposits.
Subcategorv; Uranium Mines
This subcategory includes all uranium mines, whether open-
pit or underground.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of settling ponds in conjunction with lime
precipitation, ion exchange (for uranium removal), barium
chloride coprecipitation (for radium removal), and secondary
settling.
The use of settling ponds is almost universal in this sub-
category; however, frequently, the ponds used are small and
have inadequate retention time. Where space limitations do
not permit use of such ponds, mechanical clarifier-floccula-
tors are acceptable alternatives for settling of suspended
solids. Adjustment of wastewater pH prior to discharge may
be necessary.
768
-------
Rationale for Selection. Nearly every uranium mine with
wastewater discharge currently practices suspended-solid
removal by the use of settling ponds. Treatment, as
practiced, is currently uniformly inadequate to achieve
acceptable levels of pollutant control.
Currently, in addition to settling ponds, the best treatment
employed at uranium mines includes the use of ion exchange
for removal of uranium from mine water. This has the dual
benefit of effluent treatment plus recovery of uranium
values. This treatment has been economically applied for
value recovery at concentrations as low as 2 mg/1 of
uranium.
Treatment, as generally practiced, is judged to be
inadequate for removal of either heavy metals or radium
concentrations in mine wastewater. The effectiveness of
barium chloride coprecipitation has been demonstrated at two
mines and two mills in this industry category where it has
been shown to reduce radium concentrations to 3 picocuries
per liter or less (dissolved). It may be necessary to add
sulfate ion (generally obtainable as a waste byproduct from
uranium milling) to effect satisfactory coprecipitation.
Lime precipitation is in use at facilities in the ore mining
and dressing industry and has been demonstrated to be
effective for heavy-metal removal. Secondary settling ponds
may be necessary for removal of precipitated solids.
Levels of Effluent Reduction Attainable. The parameters
selected for control and levels of effluent reduction
attainable by use of BPCTCA for this subcategory are
presented in Table IX-22. No limitations are proposed for
TOG, Mo, and V reductions using BPCTCA.
Subcatecrorv; Mills Processing Uranium Ores by_ Acid or
Alkaline Leaching
This subcategory includes mills processing uranium ores
alone, and ores containing both uranium and vanadium, by
leaching techniques (whether acid, or alkaline) and
associated chemical beneficiation techniques.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is the
use of tailings impoundment(s), recycle of process waters,
evaporation (where practicable) of wastewater, and, where
topography or climate require it, discharge following
removal of radium by barium chloride coprecipitation,
removal of heavy metals by lime precipitation, settling, and
769
-------
TABLE IX-22. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-URANIUM MINES
PARAMETER
pH
TSS
COD
Zn
Ra 226 (diss)
Ra 226 (total)
U
CONCENTRATION (mg/1)
IN EFFLUENT
30-day average
6" to 9*
20
100
0.5
3**
10"»
2
24-hour maximum
6" to 9"
30
200
1.0
10"'
30»*
4
•Value in pH units
*No limitations proposed for BPCTCA
"Value in picocuries per liter
770
-------
aeration. Mills recovering uranium concentrate by ammonia
precipitation can reduce the ammonia concentrations in the
discharge and recover portions of the reagent by steam
stripping of waste streams from the precipitation stages.
Mills using alkaline leach techniques can prevent the build
up of radiuim and sulfate ions that may adversely affect the
recycling of leaching solutions by separating effluents from
the purification, or sodium-removal stages.
Rationale for Selection. Approximately 95 percent of the
mills in this subcategory presently impound and evaporate
wastewater. However, one mill examined in this study is
located in mountainous terrain with limited suitability for
the building of evaporation ponds. There are currently no
milling operations producing uranium or uranium with
vanadium byproduct as their prime product in wet or humid
climates. Raw wastes from mills using the acid leaching
process remain acid at the process discharge and contain
various heavy metals. Acid leach wastes are, therefore,
generally not suitable for recycle without additional or
specialized treatment. Wastes from the alkaline leaching
process require only recarbonization, a normal industry
practice, in preparation for recycle, provided that sodium
and sulfate ions are either not introduced to or bled off
from the recycle loop.
Levels of. Effluent Reduction Attainable. The parameters
selected for control and levels of effluent reduction
attainable by use of BPCTCA for this subcategory are
presented in Table IX-23.
Metal Ores, Not Elsewhere Classified
This group of metal-ore operations includes mining and
milling of ores of antimony, beryllium, platinum, tin,
titanium, rate-earth metals, and zirconium.
Category; Antimony Ores
Subcategorv; Antimony-Ore Mines Alone
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is lime
precipitation (and sulfide precipitation for antimony
removal if necessary) in conjunction with removal of
suspended solids by the use of settling impoundments.
To implement the above technology, mechanical clarification
devices (e.g., clarifiers, clari-flocculators, etc.) may
771
-------
TABLE IX-23. PARAMETERS SELECTED AND EFFLUENT
LIMITATIONS RECOMMENDED FOR BPCTCA -
URANIUM MILLS
PARAMETER
PH
TSS
COD
NH3
As
Mo
V
Zn
Ra226 (diss)
Ra226 (total)
CONCENTRATION (mg/J )
IN EFFLUENT
30-day average
6 to 9*
20
500
100
0.5
t
t
0.5
3"*
10"*
24-hour maximum
6 to 9*
30
—
—
1
t
t
1
10"
30" "
•Value in pH units
tNo limitations proposed for BPCTCA
"Value in picocuries per liter
772
-------
also be used. Adjustment of pH by neutralizing agents may
be necessary at selected locations prior to discharge.
Secondary settling ponds may be necessary for removal of
precipitated solids.
Rationale for Selection. Chemical precipitation for
removal of heavy metals by lime addition is well-documented
and has been well-demonstrated in the ore mining and
dressing industry. Sulfide precipitation is the only
effective economical method for'removal of antimony to low
levels. The use of settling impoundments is an almost-
universal treatment method for removal of suspended solids.
Present treatment methods in use in this subcategory consist
of settling alone. Heavy-metal discharges resulting from
the use of this treatment alone indicate its uniform
inadequacy.
Level of Effluent Reduction Attainable. The parameters
selected for control and effluent reduction attainable by
use of the above technology in this subcategory are
presented in Table IX-2U.
Subcategorv; Antimony Mills Using Flotation Process
Identification of BPCTCA . The best practicable control
technology currently available for this subcategory is zero
discharge by impoundment and/or recycle of process waste-
water.
To achieve zero discharge by recycling, additional secondary
settling of process water may be necessary to reduce slime
content. Adequate impoundment area is necessary to achieve
zero discharge by impoundment.
Rationale for selection. The only flotation mill operating
for primary-product recovery of antimony is currently
achieving zero discharge by impoundment. Recycle of process
water, with additional settling treatment for suspended-
solid removal should not present any technical difficulty.
Levels of Effluent Reduction Attainable. Zero discharge of
process wastewater is attainable by implementation of this
technology.
773
-------
TABLE IX-24. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-ANTIMONY MINES
PARAMETER
PH
TSS
As
Fe
Sb
Zn
CONCENTRATION (mg/2,)
IN EFFLUENT
30-day average
6* to 9"
20
0.5
1.0
0.5
0.3
24-hour maximum
6* to 9*
30
1.0
2.0
1.0
1.0
'Value in pH units
774
-------
Subcategorv; Mills Ob-tainingr Antimony As a Byproduct of
Base» or Precious-Metal Milling Operation ~"
This subcategory includes operations where antimony is
recovered from a concentrate at a smelter or refinery
(antimony extraction plant).
Identification of BPCTCA. No separate limitations are
proposed for this subcategory. Limitations developed for
the subcategory of the primary metal recovered are
recommended for this subcategory.
Category; Beryllium Ores
Subcategorv; Beryllium Mines
Identification of. BPCTCA. The best practicable control
technology currently available is zero discharge by
impoundment of mine wastewater.
Rationale for selection. The single operating mine in this
subcategory is achieving zero discharge by impoundment.
Levels of Effluent Reduction Attainable. Zero discharge of
mine wastewater is attainable by implementation of this
technology.
Subcategorv: Beryllium Mills
Identification of BPCTCA. The best practicable control
technology currently available is the total impoundment of
process wastewater.
Rationale for Selection. The above technology is currently
practiced at the single beryllium mill now operating.
Levels of_ Effluent Reduction Attainable. Zero discharge of
process wastewater is attainable by implementation of this
technology.
Category; Piatinum Ores
This category represents facilities operated for the mining
and concentration of platinum ores by gravity-separation
methods. Most platinum in the U.S. is obtained as a
byproduct of smelting and refining of base or precious
metals. A single operating facility currently obtains
platinum concentrates by dredging and gravity separation for
775
-------
concentration of platinum and a snail amount (3 to 4 percent
of concentrates) of byproduct gold.
Identification of BPCTCA. The best practicable control
technology currently available is the use of settling ponds
for control of suspended-solid levels.
An alternative to implementation of this technology is the
pumping of wastewater back over tailings for sand and gravel
filtration, but a settling impoundment of some type will be
required for primary settling before discharge.
Rationale for Selection. The single operating facility of
this type currently employs settling ponds and filtration
through sands prior to discharge. Therefore, no additional
costs will be incurred.
Levels of Effluent Reduction Attainable. The parameters
chosen for control and the levels of effluent reduction
attainable for this category are presented in Table IX-25.
Subcateaorv; Rare-Earth Ores
Subcategorv; Mines Operated for Obtaining Primary or
Byproduct Rare Earth Ores
This subcategory is represented by one rare-earth mine,
which currently has no discharge of mine water.
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is zero
discharge by impoundment and/or reuse of mine water as
process water in a mill.
Rationale for Selection. currently, no rare-earth-ore
mines exist which discharge wastewater. An operation
located in the arid region of the U.S. might practice total
impoundment should mine wastewater be encountered.
Levels of Effluent Reduction Attainable. Zero discharge of
pollutants can be attained should mine wastewater result.
Subcategorv; Rare Earth Ore Mills Using Flotation or
Leaching Process ————.
This subcategory includes a single operation extracting
rare earth metals from rare-earth ores by means of a
flotation and leaching process.
776
-------
TABLE IX-25. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-PLATINUM MILLS AND
MINES USING GRAVITY SEPARATION METHODS
PARAMETER
PH
TSS
CONCENTRATION (mg/Jl)
IN EFFLUENT
30-day average
6" to 9"
30
24-hour maximum
6« to 9*
50
•Value in pH units
777
-------
Identification of BPCTCA. The best practicable control
technology currently available for this subcategory is zero
discharge by separation of waste streams, followed by
impoundment and evaporation of leaching-process wastewater
and recycle of flotation-process water from a sedimentation
impoundment.
Rationale for Selection. The single operating facility in
this subcategory is currently practicing BPCTCA.
Levels of Effluent Reduction Attainable. Zero discharge of
process-water effluent is attainable by this technology.
Subcateqorv; Mills or Mine/Mills Obtaining Rare Earth
Minerals by Gravity Methods
The rare-earth mineral monazite is currently recovered as a
byproduct of placer operations for titanium minerals.
BPCTCA for this subcategory is covered under the appropriate
titanium-ore subcategory. No separate or additional limit-
ations are proposed.
Category: Tin Ores
Currently, tin is primarily recovered at one location in the
U.S. as a byproduct of molybdenum mining and milling. A
small amount of tin is also produced at dredging operations
for gold as a byproduct of placer mining in Alaska, and a
placer operation in New Mexico, and the levels of effluent
reduction attainable are covered under the appropriate
ferroalloy-ore or gold-ore subcategory.
Although tin is recovered by placer and gravity methods as
well as by magnetic and electrostatic separation or
extraction, no major deposits are currently exploited in the
U.S.
Caqeqorv: Titanium Ores
Subcateqorv; Titanium Mines
Currently in the U.S., there is one operation mining a
titanium-ore deposit by open-pit methods.
Identification of BPCTCA. The best: practicable control
technology currently available is neutralization in
conjunction with the use of a settling pond for suspended
solid removal. pH adjustment prior to discharge of
wastewater may be necessary.
778
-------
Rationale for Selection. Current practice in the single
operating facility is impoundment and discharge of mine
wastewater. Retention time for this small settling pond is
short?, and treatment for suspended solids in the discharge
water is inadequate. Expansion of the settling pond to
allow increased retention time is necessary. Neutralization
of mine waters is necessary to maintain pH values at levels
which will prevent solubilization of heavy metals.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable by use
of the above technology are presented in Table IX-26.
Subcategorv; Titanium Mills or Mine/Mills using
Electrostatic and/oMaemetic plus Gravity and/or Flotation
Methods
This subcategory is currently represented by one milling
operation, which concentrates ilmenite from an ilmenite/
magnetite ore.
Identification of BPCTCA. The best practicable technology
currently available is the use of tailing ponds with lime
precipitation adjustment of wastewater pH prior to discharge
may be necessary of process water.
Rationale for selection. Currently, the one operating mill
in this subcategory is practicing impoundment and recycle
during approximately ten months of the year. Lime
precipitation is we11-documented and has been well-
demonstrated in other segments of the ore mining and
dressing industry, and its use is necessary to reduce heavy-
metal concentrations in discharge water.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by use of the above technology are presented in
Table IX-27.
Subcategory; Titanium Dredge Mine With wet separation
This subcategory includes operations engaged in the dredge
mining of placer deposits of sands containing rutile,
ilmenite, and leucoxene. Monazite, zircon, and other heavy
minerals are also obtained as byproducts from these
operations. Milling techniques employed in this subcategory
include the use of wet gravity methods in conjunction with
electrostatic and/or magnetic methods.
779
-------
TABLE IX-26. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-TITANIUM MINES
PARAMETER
PH
TSS
Fe
CONCENTRATION (mg/i)
IN EFFLUENT
30-day average
6" to 9*
20
1.0
24-hour maximum
6* to 9"
30
2.0
•Value in pH units
780
-------
TABLE IX-27. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-TITANIUM MILLS
PARAMETER
PH
TSS
F«
Ni
Zn
CONCENTRATION (mg/£)
IN EFFLUENT
30-day ivtragt
6" to 9*
20
0.1
0.1
0.5
24-hour maximum
6"to9»
30
0.2
0.2
1.0
•Valua in pH units
781
-------
Identification of BPCTCA. The best practicable control
technology currently available for this category is settling
impoundment with maintenance of a pH of 3.5, secondary
settling, and neutralization.
Current practice of this technology normally involves the
use of three sedimentation ponds. The first pond is
maintained at acid pH (3.5) for control of organic matter.
Secondary settling is practiced at the second pond, with a
third "polishing pond" being used for final clarification
and neutralization by lime addition.
Rationale for Selection. Three operations are currently
practicing this technology, and it has been demonstrated
effective for reduction of COO resulting from humic
materials present in the process wastewater. Suspended-
solid levels are maintained at low values due to the use of
three settling ponds.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by use of the above technology are presented in
Table IX-28.
Category; Zirconium Ores
Zircon is produced as a byproduct of titanium placer
operations. Mining and milling methods are inseparable from
those used in titanium dredge mining and wet milling. As a
result, no separate technology or limitations are proposed
for zirconium ores.
782
-------
TABLE IX-28. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BPCTCA-TITANIUM DREDGE MINE
WITH WET SEPARATION MILL
PARAMETER
pH
TSS
COD
Fa
CONCENTRATION (mg/i)
IN EFFLUENT
30-day average
6* to 9*
20
50
1.0
24-hour maximum
6f to 9f
30
-
2.0
Value in pH units
783
-------
SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE,
GUIDELINES AND LIMITATIONS
INTRODUCTION
The effluent limitations which must be achieved by July 1,
1963 are based on the degree of effluent reduction
attainable through the application of the best available
technology economically achievable (BATEA). For the ore
mining and dressing industry, this level of technology was
based on the very best control and treatment technology
employed by a specific point source within each of the
industry's subcategories, or which is readily transferable
from one industry process to another. In Section IV, the
ore mining and dressing industry was initially divided into
ten major categories. several of those major categories
have been further subcategorized, and, for reasons explained
in Section IV, each subcategory will be treated separately
for the recommendation of effluent limitations guidelines
and standards of performance. As also explained in Section
IV, the subcategories presented in this section will be
consolidated, where possible, in the regulations derived
from this development document.
The following factors were taken into consideration in
determining the best available technology economically
achievable:
(1) age of equipment and facilities involved;
(2) process employed;
(3) engineering aspects of the application of various
types of control techniques;
(4) process changes;
(5) cost of achieving the effluent reduction resulting
from application of BATEA; and
(6) nonwater-quality environmental impact (including
energy requirements).
In contrast to the best practicable control technology
currently available, best available technology economically
achievable assesses the availability in all. cases of in-
process controls as well as control or additional treatment
techniques employed at the end of a production process. In-
process control options available which were considered in
establishing these control and treatment technologies
include:
785
-------
(1) alternative water uses
(2) water conservation
(3) waste-stream segregation
(4) water reuse
(5) reuse of wastewater constituents
(6) waste treatment
(7) good housekeeping
(8) preventive maintenance
(9) quality control (raw material, product, and
effluent)
(10) monitoring and alarm systems.
Those plant processes and control technologies which, at the
pilot plant, semi-works, or other level, have demonstrated
both technological performances and economic viability at a
level sufficient to reasonably justify investing in such
facilities were also considered in assessing the best avail-
able technology economically achievable. Although economic
factors are considered in this development, the costs for
this level of control are intended to be for the top-of-the-
line of current technology subject to limitations imposed by
economic and engineering feasibility. However, this
technology may necessitate some industrially sponsored
development work prior to its application.
Based upon the information contained in Sections in through
IX of this report, the following determinations were made on
the degree of effluent reduction attainable with the appli-
cation of the best available technology economically
achievable in the various categories and subcategories of
the ore mining and dressing industry.
GENERAL WATER GUIDELINES
Process Water
Process water is defined as any water contacting the ore,
processing chemicals, intermediate products, byproducts, or
products of a process, including contact cooling water. All
process-water effluents are limited to the pH range of 6.0
to 9.0 unless otherwise specified.
Cooling Water
In the ore mining and dressing industry, cooling and process
waters are sometimes mixed prior to treatment and discharge.
In other situations, cooling water is discharged separately.
Based on the application of best available technology econo-
786
-------
mically achievable, the recommendations for the discharge of
such cooling water are:
An allowed discharge of all non-contact cooling waters
provided that these conditions are met:
(1) Thermal pollution be in accordance with standards
to be set by EPA policies. Excessive thermal rise
in once-through, non-contact cooling water in the
ore mining and dressing industry has not been a
significant problem.
(2) All non-contact cooling waters be monitored to
detect leaks of pollutants from the process.
Provisions should be made for treatment to the
standards established for the process-wastewater
discharges prior to release in the event of such
leaks.
(3) No untreated process waters be added to the cooling
waters prior to discharge.
The above non-contact cooling-water recommendations should
be considered as interim, since this type of water plus
blowdown for water treatment, boilers, and cooling towers
will be regulated by EPA at a later date as a separate
category.
Storm-Water Runoff
Storm water runoff may present pollution control problems
whenever the runoff passes over an area disturbed by the ore
mining operation or the ore dressing operation, where there
are stock piles of ore to be processed or where waste
materials are stored.
Facilities should be designed to treat or contain this
runoff, however, regardless of the size of the treatment
facility, there are natural occurrences which might result
in the system being overloaded with the resultant discharge
violating the effluent limitations set forth in this
section. To provide guidance to be used in the design of a
treatment system and to avoid the legal problems that might
result if an unauthorized discharge occurs, the following
provisions are recommended:
Any untreated overflow which is discharged from facilities
designed, constructed and operated to contain all process
generated wastewater and the surface runoff to the treatment
787
-------
facility, resulting from a 25-year, 24-hour precipitation
event and which occurs during or directly as a result of a
precipitation event shall not be subject to the limitations
set forth in this section.
The term "25-year, 24-hour precipitation event" means the
maximum 24-hour precipitation event with a probable
reoccurrence of once in 25 years as defined by the National
weather Service and Technical Paper No. 40, "Rainfall
Frequency Atlas of the U.S.,: May 1961 and subsequent
amendments or equivanlent regional or rainfall probability
information developed therefrom. It is intended that when
subsequent events occur each of which results in less
precipitation than would occur during a "25-year, 24-hour
precipitation event," that result in an equivalent amount of
runoff, the same provisions will apply.
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE, BY ORE
CATEGORY AND SUBCATEGORY
Category; Iron Ores
Subcategorv: Iron-Ore Mines
Identification of BATEA. The best available technology eco-
mically achievable for the wastewater resulting from the
mining of iron ore is the use of settling ponds with
coagulation/ flocculation systems in conjunction with
chemical precipitation by lime to a pH of 8.5 to 9.
To implement the above technology, secondary settling may be
required for removal of precipitated solids.
Rationale for Selection. The use of lime neutralization
and precipitation has been well-demonstrated in the ore
mining and dressing industry, as well as in the coal mining
industry, where it is used for control of acid mine drainage
and for precipitation of metals. Application of this
technology in the bauxite mining industry has been well-
documented, both on a full-scale basis and on a pilot scale.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by the use of this technology are presented in
Table X-l.
788
-------
TABLE X-1. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-IRON-ORE MINES
PARAMETER
PH
TSS
Dissolved Fe
CONCENTRATION (mg/4)
30-day average
6* to 9»
20
0.6
daily maximum
6»to9«
30
1.0
•Value in pH units
789
-------
Subcategorv: Iron Ore Mills Employing Physical and Chemical
Separation And Mills Using Only Physical Separation
(Magnetic and Non-Magnetic|^
Identification of BATEA. The best available technology
economically achievable for the treatment of wastewater
resulting from milling processes used in this subcategory is
the use of tailing impoundments with
coagulation/flocculation systems in conjunction with
chemical precipitation by lime addition to a pH of 8.5 to 9.
To implement the above technology, secondary settling ponds
may be required for removal of precipitated solids.
Treatment requirements can be substantially reduced by
partial recycling of process water, a practice which has
widespread use in this subcategory. Adjustment of
wastewater pH prior to discharge may be necessary.
Rationale for Selection. The use of lime neutralization
and precipitation has been well-demonstrated in the ore
mining and dressing industry, as well as in the coal mining
and bauxite mining industries, where it has been used
extensively for control of acid mine drainage and heavy-
metal removal.
Levels of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by application of BATEA are presented in Table X-
2.
Subcategorv; Iron-Ore Mills Employing Magnetic and Physical
Separation (Mesabi Range)
Identification of BATEA. The best available technology
economically achievable for this subcategory is zero
discharge of process wastewater. (Same as BPCTCA.)
Category; Copper Ores
Subcategorv; Copper-Ore Mines
Identification of BATEA. The best available technology
economically achievable for this subcategory is the use of
lime precipitation and settling or clarification aided by
flocculant addition if necessary. This is essentially the
same as BPCTCA; however, by optimum pH control and more
efficient operation of the system, the recommended levels
can be obtained.
790
-------
TABLE X-2. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-IRON-ORE MILLS EMPLOYING
PHYSICAL METHODS AND CHEMICAL SEPARATION AND
ONLY EMPLOYING PHYSICAL SEPARATION
PARAMETER
pH
TSS
Dissolved Fe
CONCENTRATION (mg/£)
IN EFFLUENT
30-day averagt
6* to 9*
20
0.5
24-hour maximum
6" to 9*
30
1.0
'Value in pH units
791
-------
Rationale for Selection. The treatment of wastewater by
lime precipitation with optimum pH control is well
documented and currently in use in the ore mining and
dressing industry.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable are
presented in Table X-3.
Subcateqorv; Copper-Ore Mines Employing Hvdrometallurgical
Processes
Identification of BATEA. The best available technology
economically achievable is zero discharge of
hydrometallurgical process wastewater. (Same as BPCTCA.)
Subcateqorv; Copper Mills Employing Vat-Leaching Process
Identification of BATEA. The best available technology
economically achievable is zero discharge of process waste-
water. (Same as BPCTCA.)
Subcateqorv; Copper Mills Employing Froth Flotation
Identification of BATEA. The best available technology
economically achievable for this subcategory is zero
discharge of process wastewater through the reuse, recycle,
and evaporation of all process waters.
Rationale for Selection. The procedures which can be
employed at flotation mills in this subcategory for
recycling are presently being demonstrated in the copper
milling industry.
Segregation of Wastewater; Water conveyed to a mill
treatment system from mine pumpout may result in excess
water and, thus, a discharge. where this occurs,
separate treatment of mine water may be necessary to
reduce the amount of water to be impounded and to
improve the water balance for a recycle system.
Evaporation ponds for a portion of wastewater may be
employed seasonally to reduce wastewater volume.
Recycle of Process Water; Process water should be
recycled from impoundments. Makeup water can be added,
when necessary, to maintain the needed volume of process
water.
792
-------
TABLE X-3. PARAMETERS SELECTED AND EFFLUENT
LIMITATIONS RECOMMENDED FOR
BATEA-COPPER MINES
PARAMETER
PH
TSS
Cu
Pb
Hg
Zn
CONCENTRATION (mg/ 1 )
IN EFFLUENT
30-day average
6* to 9*
20
O.OS
0.1
0.001
0.5
24-hour maximum
6* to 9*
30
0.1
0.2
0.002
1.0
•Value in pH units
793
-------
Tailing-Pond Seepage; Seepage, where it occurs, should
be diverted to a ditch and pumped back into the tailing
pond.
Current operations in this subcategory employ partial or
complete recycle of process water. Application of methods
for reduction of wastewater flow, and recycle of process
water, will enable the zero-discharge limitation to be met.
Levels of Effluent Reduction Attainable. Zero discharge of
process wastewater is attainable by the implementation of
this technology.
Category: Lead and Zinc ores
Subcategorv; Lead and Zinc Mines
Identification of BATEA. The best available technology
economically achievable for this subcategory is the use of
lime precipitation and settling or clarification aided by
flocculant addition if necessary. This is essentially the
same as BPCTCA; however, by optimum pH control and more
efficient operation of the system, the recommended levels
can be obtained.
Rationale for Selection. The treatment of wastewater by
lime precipitation with optimum pH control is well
documented and currently in use in the ore mining and
dressing industry.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable are
presented in Table X-4.
Subcategorv; Lead and Zinc Mills
Identification of BATEA. The best available technology
economically achievable is zero discharge through total
recycle and impoundment of process water.
To implement this technology. Segregation and treatment of
mine water separately from process water may be necessary at
some locations because of an excess water balance adversely
affecting the ability to impound.
Rationale for Selection. The fact that several lead/zinc
and copper sulfide ore mills do operate in a total-recycle
mode suggests that zero discharge is an attainable mode of
operation for all such mills. The technological feasibility
794
-------
TABLE X-4. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-LEAD AND ZINC MINES
PARAMETER
pH
TSS
Cu
H0
Pb
Zn
CONCENTRATION (mg/2,1
IN EFFLUENT
30-day average
6» to 9'
20
0.05
0.001
0.1
0.5
24-hour maximum
6» to 9"
30
0.1
0.002
0.2
1.0
•Value in pH units
795
-------
of recycle at lead/zinc/copper (sulfide-mineral) mills has
been demonstrated and, with adequate development work,
should be applicable to all mill operations. In some cases,
engineering modifications—and, perhaps alternative modes of
solids disposal and retention—would appear to provide
feasible solutions to water-balance problems. For example,
dewatering of tailings in a clarifier with recirculation of
the overflow may be necessary where precipitation presently
creates difficulty for total recycle and impoundment.
Levels of Effluent Reduction Attainable, zero discharge of
effluent will result from implementation of BATEA.
Category; Gold Ores
Subcateqorv; Gold Mines (Alone)
Identification of BATEA. The best available technology
economically achievable for this subcategory is the use of
lime precipitation and settling or clarification aided by
flocculant addition if necessary. This is essentially the
same as BPCTCA; however, by optimum pH control and more
efficient operation of the system, the rescommended levels
can be obtained.
Rationale for Selection. The treatment of wastewater by
lime precipitation with optimum pH control is well
documented and currently in use in the ore mining and
dressing industry.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable are
presented in Table X-5.
Subcateaorv; Gold Mines or Mine/Mills Employing
Amalgamation
Identification of BATEA. The best available technology
economically achievable is zero discharge of process water
by a process change to cyanidation extraction, settling pond
treatment, and recycle of decant water.
To implement this technology, a higher degree of control
over the quality of the reclaimed water can be maintained if
the tailing-pond decant is collected in a secondary or
polishing pond prior to recycle back to the mill circuit.
Rationale for Selection. The BATEA identified for this
subcategory has demonstrated application and reliability in
796
-------
TABLE X-5. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-GOLD MINES
PARAMETER
PH
TSS
Cu
Hfl
Pb
Zn
CONCENTRATION (mg/ I }
IN EFFLUENT
30-day average
6* to 9*
20
0.05
0.001
0.1
0.5
24-hour maximum
6" to 9*
30
0.1
0.002
0.2
1.0
•Vita* i* pH unitt
797
-------
the gold milling industry. Total recycle of tailing-pond
decant is currently practiced by one mill. Total-recycle
systems are also being employed in several other milling
subcategories. The change in process from amalgamation to
cyanidation will entail engineering modifications. The
feasibility of this process change is demonstrated by the
recent change of a gold mill from amalgamation to
cyanidation.
Levels 2l Effluent Reduction Attainable. Zero discharge of
process wastewater is attainable by implementation of this
technology.
Subcategorv; Gold Mills or Mine/Mills Employing Cyanidation
Identification of BATEA. The best available technology
economically ahcievable in this subcategory is no discharge
of process wastewater by impoundment or complete recycle of
process wastewater. (Same as BPCTCA) .
Subcateqory;. Gold Mills Employing Froth Flotation Process
Identification of BATEA. The best available technology
economically achievable for this subcategory is zero
discharge by impoundment and recycle of process water.
The recommended technology is essentially the same as BPCTCA
except that engineering modifications of the process-water
system are designed for total recycle and impoundment.
Rationale for Selection. The single operating facility in
this subcategory currently is achieving zero discharge, nine
to ten months of the yearr by prevention of runoff entry
into tailing impoundments, increased impoundment volume, and
total recycle of process water. Optimization of the
existing system by minor modifications and engineering
changes should enable attainment of zero discharge.
Levels 2i Effluent Reduction Attainable, zero discharge of
process wastewater is attainable by implementation of this
technology.
SS^ *illB ~ ^^ Employing Gravity
Identification of BATEA. The best available
economically achievable is the use of settling or
impoundments. (Same as BPCTCA.)
798
-------
Subcategorv; Mill Operations Where Gold is Recovered as
Byproduct of Base Metal Millinq Operation —
Identification of BATEA. No separate limitations are
recommended for this subcategory. The BATEA for this
subcategory is the same as BATEA for the primary metal
recovered.
Category; SiIver Ores
Subcateaorv; Silver Mines (Alone)
Identification of BATEA. The best available technology
economically achievable for this subcategory is the use of
lime precipitation and settling or clarification aided by
flocculant addition if necessary. This is essentially the
same as BPCTCA; however, by optimum pH control and more
efficient operation of the system, the recommended levels
can be obtained.
* Rationale for Selection. The treatment of wastewater by
lime precipitation with optimum pH control is well
documented and currently in use in the ore mining and
dressing industry.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable are
presented in Table X-6.
Subcategorv; Silver Mills Employing Froth Flotation
Identification of BATEA. The best available technology
economically achievable is zero discharge by use of total
recycle of process water and/or total impoundment.
Rationale for Selection. Currently, two silver mills are
recycling their process water. One mill reclaims all of its
tailing pond decant while the second presently reclaims 60
percent of its tailing pond decant. Recycle of all process
water is currently technically achievable, by engineering
modifications of the process water system designed for total
recycle and impoundment. The technical feasibility of
achieving no discharge is discussed in detail in Section
VII.
799
-------
TABLE X-6. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-SILVER MINES (ALONE)
PARAMETER
PH
TSS
Cu
Hg
Pb
Zn
CONCENTRATION (mg/ I )
IN EFFLUENT
30-day average
6* to 9*
20
0.05
0.001
0.1
0.5
24-hour maximum
6" to 9"
30
0.1
0.002
0.2
1.0
•Valua in pH units
800
-------
Levels of Effluent Reduction Attainable
Zero discharges of process wastewater is attainable by
implementation of this technology.
Subcatecrorv: Silver Mills or Mine/Mills using CvanidatAon
Identification of BATEA. The best available technology
economically achievable is attainment of zero discharge by
total recycle and/or total impoundment of process
wastewater. (Same as BPCTCA.)
Subcategorv: Silver Mills or Mine and Mills
Amalgamation
Identification of BATEA. The best available technology
economically achievable for this subcategory is the
attainment of zero discharge by a process change to
cyanidation and total recycle and/or total impoundment of
process wastewater.
In order to achieve total recycle, a higher degree of
control over the quality of the reclaim water can be
maintained if the tailing-pond decant is collected in a
secondary settling, or polishing, pond prior to recycle back
to the mill circuit. The secondary pond will serve as the
surge pond in the recycle system.
Rationale for Selection. The recommended technology has
been demonstrated as feasible in both the gold and silver
milling industries. Recycle systems are also being employed
in the copper, lead, and zinc milling industries. Process
modification from amalgamation to cyanidation has been
technically accomplished in the gold milling industry with
no apparent loss of recovery and with elimination of high
mercury levels in the discharge.
Levels of Effluent Reduction Attainable. No discharge of
process wastewater is attainable by implementation of the
above technology.
Subcategory: Silver Mills Using Gravity Separation Methods
Identification of BATEA. The best available technology
economically achievable is the use of settling impoundment.
(Same as BPCTCA.)
801
-------
Subcateqory: Mill Operations where Silver is Recovered as
Byproduct of Base-Metal Milliner Operation
Identification of BATEA. No separate limitations are
recommended for this subcategory. The BATEA for this
subcategory is the same as BATEA for the primary metal
recovered.
Category; Bauxite Ores
Identi fi cation of BATEA. The best available technology
economically achievable for this subcategory is use of lime
precipitation and settling with optimized pH control and
operating efficiencies.
Rationale for Selection. The recommended treatment is
currently being operated at one bauxite operation with no
technical difficulties. Although relatively low flow
conditions prevail, a large-scale treatment plant is
currently under construction and is expected to be
operational in mid-1975.
Levels of Effluent Reduction Attainable. The parameters
selected and effluent limitations attainable by
implementation of this technology are presented in Table X-
7.
Category; Ferroalloy Ores
Subcategorv; Ferroalloy Mines Producing Greater Than 5fOOO
Metric Tons (5512 Short Tons) Per Year
Identification of BATEA. The best available technology
economically achievable is use of lime precipitation in
conjunction with a settling pond and the use of flocculants
and secondary settling. Addition of lime prior to removal
of suspended solids is desirable.
In selected instances, the use of coprecipitation by ferric
sulfate, or ion exchange, for removal of molybdenum may be
necessary. An alternative method for suspended-solid
removal is the use of a mechanical clari-flocculator.
Rationale for Selection. The use of chemical flocculants
and secondary settling is a common practice in the ore
mining and dressing industry and has been demonstrated
effective. The limitations on molybdenum are met at
existing mines by the practice of sound water management
within the mine (preventing contact with finely divided
802
-------
TABLE X-7.. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-BAUXITE MINES (ACID OR ALKALINE
MINE DRAINAGE)
PARAMETER
PH
TSS
Al
Fe
Zn
CONCENTRATION (mg/A)
IN EFFLUENT
30-day average
6* to 9*
20
1.0
0.5
0.1
24-hour maximum
8" to 9»
30
2.0
1.0
0.2
'Value in pH units
803
-------
ore). The removal of molybdenum by coprecipitation or ion
exchange is currently being practiced at a pilot plant and
on the laboratory scale.
Levels of Effluent Reduction Attainable. The parameters
selected and levels of effluent reduction attainable are
presented in Table X-8.
Subcategorv; Ferroalloy Mills or Mines and Mills Processing
Less than 5,OOP Metric Tons (5,512 Short Tons) per Year
(other than Ore Leaching)
Identification of BATEA. The best available technology
economically achievable is the use of settling or tailing
ponds in conjunction with neutralization. (Same as BPCTCA.)
Subcategorv; Mills Processing More Than 5.000 Metric Tons
(5,512 Short Tons) of Ferroalloy Ores per Year By Physical
Methods
Identification of BATEA. The best available technology
economically achievable is the addition of total process
water recycle to BPCTCA (partial recycle, lime
precipitation, tailing pond, flocculation, and secondary
settling).
Rationale for Selection. There are no technical obstacles
to process-water recycle at these operations. Effective
suspended solid removal precludes deleterious effects from
circulating slimes on recovery. At certain locations, total
recycle with zero discharge might be employed, eliminating
the need for lime precipitation.
Levels of Effluent Reduction Attainable. The parameters
selected and effluent reduction attainable by implementation
of this technology are presented in Table x-9.
Subcategory; Mills Processing More Than 5,000 Metric Tons
(5,512 Short Tons) of Ferroalloy ores per Year ByFlotation
Methods
Identification of BATEA. The best available technology
economically achievable is the addition of process-water
recycle, oxidation (aeration, chlorination, or ozonation),
and coprecipitation or ion exchange.
Rationale for Selection- The use of recycle to reduce the
volume of water discharged, and the employment of treatment
processes aimed specifically at the removal of COD, cyanide,
804
-------
TABLE X-8. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS RECOMMENDED
FOR BATEA-FERROALLOY-ORE MINES PRODUCING > 5000 METRIC
TONS (5,512 SHORT TONS) PER YEAR.
PARAMETER
pH
TSS
As
Cd
Cu
Mo
Pb
Zn
CONCENTRATION img/l)
IN EFFLUENT
30-day average
6* to 9*
20
0.5
0.05
0.05
2,0
0.1
0.1
24-hour maximum
6* to 9*
30
1.0
0.1
0.1
4.0
0.2
0.2
'Value in pH units
805
-------
TABLE X-9. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-FERROALLOY-ORE MILLS
PROCESSING MORE THAN 5,000 METRIC TONS
(5,512 SHORT TONS) PER YEAR BY PHYSICAL METHODS
PARAMETER
pH
TSS
As
Cd
Cu
Mo
Zn
CONCENTRATION (mg/ 1 )
IN EFFLUENT
30-day average
6Mo9«
20
0.5
0.05
0.05
2.0
0.1
24-hour maximum
6" to 9*
30
1.0
0.1
0.1
4.0
0.2
'Value in pH units
806
-------
and molybdenum, will effect substantial reduction in total
pollutant load discharged from operations in this
subcategory. Treatment technology is drawn from pilot-plant
studies and examples of waste treatment in other industries,
as well as from other segments of the ore mining and milling
industry. In some cases, substantial process development
and optimization effort will be required for the successful
application of selected treatment technology in the
ferroalloy-ore mining and milling industry.
As discussed in Section IX, recycle can be difficult to
apply successfully in flotation operations—particularly, in
fatty-acid floats. Nonetheless, the industry affords
numerous examples of operations successfully practicing a
high degree of water reuse. Although simple sulfide-float
circuits are found to be most compatible with recycle,
examples of recycle may be cited even in plants with complex
fatty-acid flotation circuits. Auxiliary techniques such as
aeration may be required to limit problems with
recirculating reagents, and, since some floats are found to
be sensitive to inorganic salts in the water, a certain
amount of bleed from some float circuits is expected to be
necessary. For some flotation circuits, extensive
development is expected to be required to achieve stable
operation with recycled water. Based on what has been
achieved in the industry to date, discharge of 25 percent or
less of process-water volume can be achieved. Zero
discharge may be attained by use of total recycle of process
water and/or by impoundment, at selected sites.
The oxidation of cyanide ion to cyanate (and, ultimately,
carbon dioxide and nitrate) and aeration for the reduction
of COD are standard treatment practices in a variety of
other industries which are applicable to flotation-mill
effluents. Since raw waste values of both cyanide and COD
are relatively low, a simple aeration or ozonation or
chlorination treatment will be effective. Such treatment
must, of course, follow removal of particulates and
oxidizable species, such as metal sulfides, from the waste
stream. Data for existing operations indicate that, for
many sites, this treatment may be rendered unnecessary by
proper reagent control and oxidization incidental to other
treatment.
Two techniques for the removal of molybdenum from solution
which are currently in the pilot-plant stage hold promise
for large-scale application and provide the basis for 1983
effluent limitations, coprecipitation with ferric hydroxide
by ferric sulfate addition, and ion exchange, both have been
807
-------
shown to be viable, although not presently optimized,
techniques. A considerable history of unintentional
collection (and subsequent rejection) of molybdenum in ion-
exchange uranium-recovery operations provides background for
the application of that technique. Coprecipitation has been
studied extensively as part of an examination of the
potential pollutions associated with molybdenum.
Levels of Effluent Reduction Attainable. The parameters
selected and effluent reduction attainable by implementation
of the above technology are presented in Table X-10.
Subcategory; Mills Processing Ferroalloy Ores By_ Leaching
Teciinigues
Identification of BATEA. The best available technology
economically achievable is the addition of further waste
segregation, air stripping, chromium reduction/ and aeration
(to reoxygenate wastewater after chromium removal) to BPCTCA
(lime precipitation, primary and secondary settling,
flocculation, and wastewater segregation).
Rationale for Selection, Segregation of waste streams from
solvent-extraction/precipitation circuits is currently
practiced at one site in the ferroalloy milling industry,
where concentrates are leached. This allows treatment of
the segregated waste stream for TDS removal by evaporation
and crystallization, and for removal of ammonia in an air
stripper. Air and steam stripping for ammonia removal are
currently practiced in several related industries and at one
site in the ferroalloy-ore mining and dressing industry.
The use of sulfur dioxide for reduction of hexavalent
chromium to trivalent forms, with subsequent precipitation
of the hydroxide, is a standard waste-treatment practice in
many industries. Application to milling wastes will require
process optimization for lower initial chromium
concentrations but does not present any insurmountable
problems.
Other treatment techniques which may be used on these waste
streams have been discussed under previous subcategories and
pose no special problems in treating leaching-mill waste
water. The feasibility of process-water recycle will be
highly variable, depending on the details of specific
operations, amount of soluble material in the ore, leaching
reagents, eluents, precipitants, etc. Zero discharge may be
achieved at specific sites.
808
-------
TABLE X-10. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-FERROALLOY-ORE MILLS
USING FLOTATION PROCESS
PARAMETER
PH
TSS
COD
Cyanide
At
Cd
Cu
Mo
Zn
CONCENTRATION (mg/£)
IN EFFLUENT
30-day average
6" to 9"
20
25
0.02
0.5
0.05
0.05
2.0
0.1
24-hour maximum
6* to 9«
30
50
0.04
1.0
0.1
0.1
4.0
0.2
•Value in pH units
809
-------
Levels of Effluent Reduction Attainable. The parameters
selected and effluent reduction attainable for this
subcategory are presented in Table X-ll.
Category: Mercury Ores
Subcategorv: Mercury Mines
Identification of BATEA. The best available technology
economically achievable is the use of chemical (lime or
sulfide) precipitation and settling impoundments.
Rationale for Selection
The recommended technology is essentially the same as BPCTCA
except that the use of sulfide ion as a precipitant for
removal of heavy metals (mercury in particular) accomplishes
more complete removal.
Levels of Effluent Reduction Attainable. The levels of
effluent reduction attainable through the use of the above
technology are presented in Table X-12.
aubcategorv; Mercury Mills or Mine/Mills Employing Gravity
separation
identification of. BATEA. The best available technology
economically achievable is zero discharge by recycle of
process water and/or total impoundment. (Same as BPCTCA.)
Subcategorv; Mercury Mills or Mine/Mills Using Flotation
Process
Identification of BATEA. The best available technology
economicallyachievable is zero discharge by the use of
total recycle and/or total impoundment of process
wastewater. (Same as BPCTCA.)
Subcategorv; Mills Recovering Mercury as a Byproduct of
Base- or Precious-Metal Concentrates Identification of
BATEA. No separate limitations or technology are proposed.
The BATEA for this subcategory is the same as BATEA for the
primary base or precious metal recovered.
810
-------
TABLE X-11. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA-FERROALLOY-ORE MILLS
USING LEACHING PROCESS
PARAMETER
pH
TSS
Ammonia
At
Cd
Cr
Cu
Zn
CONCENTRATION (mg//)
IN EFFLUENT
30-day average
6" to 9"
20
SO
0.5
0.05
0.05
0.15
0.1
24-hour maximum
6* to 9*
30
100
1.0
0.1
0.1
0.30
0.2
'Valua in pH units
811
-------
TABLE X-12. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR BATEA - MERCURY MINES
PARAMETER
PH
TSS
Hg
Ni
CONCENTRATION (mg/^ )
IN EFFLUENT
30-day average
6' to 9*
20
0.0005
0.1
24-hour maximum
6* to 9*
30
0.001
0.2
•Value in pH units
812
-------
Category; Uranium, Radium, and Vanadium Ores
Subcategorv; Uranium Mines
Identification of BATEA. The best available technology
economically achievable is the use of BPCTCA technology in
conjunction with sulfide precipitation, ion exchange for Mo
removal, ferrous sulfate coprecipitation for V removal, and
aeration.
Rationale for Selection. The use of sulfide precipitation
for removal of heavy metals has been demonstrated in the
chloralkalai industry, as well as in numerous pilot- and
bench-scale experimental treatment systems. Relatively
simple, inexpensive systems are available for use in
implementing this treatment. Ion-exchange technology has
been demonstrated in the uranium industry as effective in
extraction of uranium values from mine or process water.
Ion-exchange resins are available which are specific for the
ions involved. Coprecipitation of vanadium, as discussed in
Section VII, is capable of removing this waste parameter to
below the levels specified. Aeration of wastewater will
assist in raising dissolved oxygen levels and in lowering of
COD.
Levels of Ef fluent Reduction Attainable. The parameters
selected for control and the effluent reductions attainable
by implementation of this technology are presented in Table
X-13.
Subcategorv; Mills Processing Uranium Ores by Acid or
Alkaline Leaching
Identification of BATEA. The best available technology
economically achievable is zero discharge by the use of
impoundment and evaporation and/or recycle.
Rationale for Selection. Approximately 95% of the
operations contained in this subcategory achieve zero
discharge by either of two methods: impoundment and
evaportation alone or impoundment, evaporation and recycle.
Raw wastewater from mills using acid leaching remains acid
at the process discharge, retains various heavy metals and
generally is not suitable for recycling without additional
or specialized treatment. Wastewater from the
alkaline-leach process is normally recycled in part. There
is one known acid-leach milling operation, located in
Colorado, which routinely discharges its wastewater.
813
-------
TABLE X-13. PARAMETERS SELECTED AND EFFLUENT
LIMITATIONS RECOMMENDED FOR
BATEA-URANIUM MINES
PARAMETER
PH
TSS
COD
As
Cd
Mo
V
Zn
Ra 226 (dist)
Ra 226 (total)
U
CONCENTRATION (mg/ I )
IN EFFLUENT
30-day average
6« to 9*
20
50
0.5
0.05
2.0
5
0.1
3*
iot
2
24-hour maximum
6» to 9«
30
100
1.0
0.1
4.0
10
0.2
iot
30t
4
•Values in pH units
^Values in picocuri«s per liter
814
-------
Levels of Effluent Reduction Attainable, zero discharge of
process wastewater is attainable by implementation of the
above technology.
Metal Ores, Not Elsewhere Classified
Category; Antimony Ores
Subcategory; Antimonv-Ore Mines (Alone)
Identification of BATEA. The best available technology
economically achievable for this subcategory is chemical
(lime and sulfide) precipitation in conjunction with
settling impoundments. (Same as BPCTCA.)
Subcatecrorv; Antimony Mills Using Flotation Process
Identification of BATEA. The best available technology
economically achievable is zero discharge by impoundment
and/or recycle of process wastewater. (Same as BPCTCA.)
Subcategorv; Mills Obtaining Antimony As a Byproduct of
Base* or Precious-Metal Milling Operation
Identification of BATEA. No separate limitations are
proposed for this subcategory. Limitations developed for
the subcategory of the primary metal recovered are
recommended for this subcategory.
Category; Beryllium Ores
Subcategorv; Beryllium Mills
Identification of BATEA. The best available technology
economically achievable is zero discharge by total
impoundment of process wastewater. (Same as BPCTCA.)
Category; Piatinum Ores
Identification o_f BATEA. The best available technology
economically achievable is the use of settling ponds. (Same
as BPCTCA.)
Category; Rare-Earth Ores
Subcategorv; Mines Operated For Obtaining Primary or
Byproduct Rare-Earth Ores
815
-------
Identification of BATEA. The best available technology
economically achievable is zero discharge by impoundment or
reuse of mine water as process water in a mill. (Same as
BPCTCA.)
Subcategorv: Rare Earth Ore Mills Using Flotation or
Leaching Proce ss
Identification of_ BATEA. The best available technology
economically achievable is zero discharge by separation of
waste streams, followed by impoundment and evaporation of
leaching-process wastewater and recycle of flotation-process
water from a sedimentation impoundment. (Same as BPCTCA.)
Subcategorv; Mills or Mine Mills Obtaining Rare Earth
Minerals By Gravity Methods
BATEA for this subcategory is covered under the appropriate
titanium-ore subcategory. No separate limitations are
proposed.
Category: Tin Ores
No areparate limitations are proposed for this category.
Category; Titanium Ores
Subcategorv; Mines Obtaining Titanium Ore fly. Lode Mining
identification of BATEA. The best available technology
economically achievable is neutralization in conjunction
with a settling pond for suspended-solid removal. (Same as
BPCTCA.) Maintenance of an alkaline pH will prevent
solubilization of heavy metals and reduce their
concentration in the discharge waters.
Subcategorv; Titanium Mills or Mine/Mills using
Electrostatic and/or Magnetic plus Gravity and/or Flotation
Methods
Identification of BATEA. The best available technology
economically achievable is zero discharge by tailing-pond
treatment and total recycle of the tailing-pond decant. In
addition, a small secondary pond may be necessary to collect
excess water from the primary pond during periods of high
precipitation. This water may either be allowed to
evaporate or be used as process makeup water during drier
periods.
816
-------
Rationale for Selection. The single mill currently
operating in this subcategory recycles its process water
following tailing-pond treatment. A discharge from this
impoundment currently exists on a seasonal basis.
Levels of Effluent Reduction Attainable. Zero discharge of
process water is attainable by implementation of the above
technology.
Subcateaorv; Titanium-Ore Mills using Physical Milling
Methods In Con junction with Dredge Mining
Identification of BATEA. The best available technology
economically achievable is settling impoundment with
maintenance of a pH of 3.5, secondary settling, and
neutralization prior to discharge. (Same as BPCTCA.)
Category: zirconium Ores
No separate limitations are recommended. The mining and
milling of zirconium (zircon) are practiced as a part of
titanium dredge mining.
817
-------
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
AND PRETREATMENT STANDARDS
INTRODUCTION
This level of technology is to be achieved by new sources.
The term "new source" is defined in the Act to mean "any
source, the construction of which is commenced after the
publication of proposed regulations prescribing a standard
of performance." This technology is evaluated by adding, to
the consideration underlying the identification of best
available technology economically achievable, a
determination of what higher levels of pollution control are
available through the use of improved production processes
and/or treatment techniques. Thus, in addition to
considering the best in-plant and end-of-process control
technology, new source performance standards are how the
level of effluent may be reduced by changing the production
process itself. Alternative processes, operating methods,
or other alternatives were considered. However, the end
result of the analysis identifies effluent standards which
reflect levels of control achievable through the use of
improved production processes (as well as control
technology), rather than prescribing a particular type of
process or technology which must be employed.
The following factors were considered with respect to
production processes which were analyzed in assessing the
best demonstrated control technology currently available for
new sources:
(a) type of process employed and process changes;
(b) operating methods;
(c) batch, as opposed to continuous, operations;
(d) use of alternative raw materials and mixes of
raw materials;
(e) use of dry, rather than wet, processes (including
substitution of recoveratie solvents from water) ;
and
(f) recovery of pollutants as byproducts.
In addition to the effluent limitations covering discharges
directly into waterways, the constituents of the effluent
discharge from a plant within the industrial category which
would interfere with, pass through, or otherwise be
incompatible with a well designed and operated publicly
819
-------
owned activated sludge or trickling filter wastewater
treatment plant were identified. A determination was made
whether the introduction of such pollutants into the
treatment plant should be completely prohibited.
GENERAL WATER GUIDELINES
The process-water, cooling-water, and storm-water runoff
guidelines for new sources are identical to those based on
best available technology economically achievable.
NEW SOURCE STANDARDS BY ORE CATEGORY
Based upon the information contained in Sections III through
X of this report, the following determinations were made on
the degree of effluent reduction attainable with the
application of new source standards for the various
categories and subcategories of the ore mining and dressing
industry.
The industry categories and subcategories which follow are
required to achieve no discharge of process wastewater based
upon best available technology economically achievable or
best practicable control technology currently available.
Iron-Ore Mills - Magnetic/Physical Process (Mesabi Range)
Copper Mines and Mills - Hydrometallurgical Process
Copper Mills - vat Leaching
Copper Mills - Froth Flotation
Lead and Zinc Mills
Gold Mills - Cyanidation Process
Gold Mills - Amalgamation Process
Gold Mills - Froth-Flotation Process
Silver Mills - Froth-Flotation Process
Silver Mills - Cyanidation Process
Silver Mills - Amalgamation Process
Mercury Mills - Gravity-separation Process
Mercury Mills - Flotation Process
Uranium (Ra, V) Mills - Acid or Alkaline Leach Process
Antimony Mills - Flotation Process
Beryllium Mines
Beryllium Mills
Rare-Earth Mines
Rare-Earth Mills
Titanium Mills - Electrostatic, Magnetic or Gravity
Processes or Flotation Processes
The same limitations are recommended as new source
standards.
820
-------
New source standards identical to BPCTCA limitations are
recommended for the following industry categories:
Bauxite Mines
Silver Mills (Mine/Mills) - Gravity Separation
Mercury Mines
Antimony Mines
Titanium Mines (Lode Ore)
Platinum Mills and Mines
Ferroalloy - Ore Mills and Mines Processing less than
5,000 metric tons (5,512 short tons) per year
Titanium Mills - Physical Processes with Dredge Mining
New source standards identical to BATEA limitations are
recommended for:
Copper-Ore Mines
Lead and Zinc Mines
Gold Mines
Gold Mills (Mine/Mills) - Gravity Separation
Silver Mines
Iron Ore Mines
Iron Ore Mills - Physical and Chemical Separation and
Mills Employing Only Physical Separation
(Magnetic and Non-Magnetic)
Ferroalloy-Ore Mills - Leaching Processes
Separate new source standards are recommended for the
following categories or subcategories as discussed on the
pages which follow:
Ferroalloy-Ore Mines processing more than 5,000 metric
tons (5,512 short tons) per year
Ferroalloy-Ore Mills (more than 5,000 metric tons- (5,512
short tons) per year) - Flotation Processes
Uranium Mines
Ferroalloy-Ore Mills Processing more than 5,000 metric
tons (5,512 short tons) per year - Physical Methods
Category; Ferroalloy Ores
Subcategorvs Ferroalloy Mines Processing More Than 5,000
Metric Tons (5.512 Short Tons) Per Year.
Identification of NSPS. For new operations, based upon
information contained in Sections III - x, a determination
has been made that the technology applicable to new sources
is identical to BATEA with the exception of coprecipitation
or ion exchange for molybdenum removal. Therefore, the
821
-------
technology recommended for qse is lime precipitation in
conjunction with a settling pond, flocculant addition, and
secondary settling.
Rationale for Selection* The selection of the above
technology is made on the basis of the best available,
demonstrated technology. The use of coprecipitation or ion
exchange is not recommended for a new source performance
standard because neither of these technologies has as yet
been demonstrated, and both will require some development
prior to application in this subcategory.
Level of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by implementation of the above technology are
presented in Table XI-1.
Subcateaorv; Ferroalloy - Ore Mills Processing More Than
5000 Metric Tons 15512 Short Tons) Per Year - Physical
Methods.
Identification of NSPS. For new operations, based upon
information contained in Sections III - X, a determination
has been made that the technology applicable to new sources
is identical to BATEA with the exception of coprecipitation
or ion exchange for molybdenum removal. Therefore, the
technology recommended for use is lime precipitation in
conjunction with a settling pond, flocculant addition, and
secondary settling.
Rationale for Selection. The selection of the above
technology is made on the basis of the best available,
demonstrated technology. The use of coprecipitation or ion
exchange is not recommended for a new source performance
standard because neither of these technologies has as yet
been demonstrated, and both will require some development
prior to application in this subcategory.
Level of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by implementation of the above technology are
presented in Table XI-2.
822
-------
TABLE XI-1. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS RECOMMENDED
FOR NSPS - FERROALLOY-ORE MINES PRODUCING > 5,000 METRIC TONS
(5,512 SHORT TONS) PER YEAR
PARAMETER
pH
TSS
As
Cd
Cu
Mo
Pb
Zn
CONCENTRATION (mg/W
IN EFFLUENT
30-day .iworiitjc
6" to 9*
20
0.5
0.05
0.05
t
0.1
0.1
24-hour maximum
6Mo9'
30
1.0
0.1
0.1
t
0.2
0.2
*Valu« in pH units
tNo limitation proposed for NSPS
823
-------
TABLE XI-2. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR NSPS-FERROALLOY-ORE MILLS
PROCESSING MORE THAN 5,000 METRIC TONS
(5,512 SHORT TONS) PER YEAR BY PHYSICAL METHODS
PARAMETER
PH
TSS
As
Cd
Cu
Mo
Zn
CONCENTRATION (mg/ i )
IN EFFLUENT
30-day average
6* to 9"
20
0.5
0.05
0.05
t
0.1
24-hour maximum
6" to 9*
30
1.0
0.1
0.1
t
0.2
* Value in pH units
t No limitation proposed for NSPS
824
-------
Subcategorv; Mills Processing More Than 5,000 Metric Tons
( ,503 Short Tons) of Ferroalloy Ores per Year by Flotation
Methods
Identification of NSPS. The information contained in
Sections III through X indicates that the best available,
demonstrated technology applicable to new sources in this
subcategory is settling, process-water recycle, and
oxidation (aeration, chlorination, or ozonation). This
technology is identical to BATEA with the exception of ion
exchange or coprecipitation.
Rationale for Selection. The reasons for selection are
discussed in detail in Section X. The use of ion exchange
or coprecipitation for removal of molybdenum and is not
specified for this level because the technologies have not
yet been demonstrated and will require some development
prior to application in this subcategory.
Level of Effluent Reduction Attainable. The parameters
selected for control and the levels of effluent reduction
attainable by implementation of the above technology are
presented in Table XI-3.
Category; Uranium Ores
Subcategory: Uranium Mines
Identification of NSPS. Based on information contained in
Sections III through X of this report, the best available,
demonstrated technology applicable to new sources in this
subcategory is the use of settling ponds, lime
precipitation, sulfide precipitation, ion exchange (for
uranium removal), barium chloride coprecipitation (for
radium removal), secondary settling, and aeration.
Rationale for selection. All technology selected for use
in this subcategory to attain NSPS levels has been
demonstrated, in the ore mining and dressing industry or in
the chlor-alkali industry- The requirement for ion-exchange
treatment (for molybdenum and vanadium removal) is not
included at this level because this technology has not yet
been demonstrated and will require some development prior to
application in this subcategory.
Levels of Effluent Reduction Attainable. The parameters
selected" and the"'levels of effluent reduction attainable by
implementation of the above technology are presented in
Table XI-
-------
TABLE XI-3. PARAMETERS SELECTED AND EFFLUENT LIMITATIONS
RECOMMENDED FOR NSPS-FERROALLOY-ORE MILLS
USING FLOTATION PROCESS
PARAMETER
pH
TSS
COD
Cyanide
As
Cd
Cu
Mo
Zn
CONCENTRATION (mg/i)
IN EFFLUENT
30-day dvnracic
6" to 9"
20
25
0.02
0.5
0.05
0.05
t
0.1
24 hour miiximum
6* to 9*
30
50
0.04
1.0
0.1
0.1
t
0.2
•Value in pH units
No limitation proposed for NSPS
826
-------
TABLE XI-4. PARAMETERS SELECTED AND EFFLUENT
LIMITATIONS RECOMMENDED FOR
NSPS-URANIUM MINES
PARAMETER
PH
TSS
COD
As
Cd
Mo
V
Zn
Ra226
U
CONCENTRATION (mg/4)
IN EFFLUENT
30-day average
6* to 9«
20
50
0.5
0.05
••
• *
0.1
3f
2
24-hour maximum
6* to 9"
30
100
1.0
0.1
*•
*•
0.2
10*
4
•Values in pH units
tValuM in picocuries per liter
••No limitation proposed for NSPS
827
-------
PRETREATMENT STANDARDS
Recommended pretreatment guidelines for discharge of plant
wastewater into public treatment works conform in general
with EPA Pretreatment Standards for Municipal Sewer Works as
published in the July 19, 1973 Federal Register and "Title
40 - Protection of the Environment, Chapter 1
Environmental Protection Agency, Subchapter D - Water
Programs - Part 128 - Pretreatment Standards,1* a subsequent
EPA publication. The following definitions conform to these
publications.
Compatible Pollutant
The term "compatible pollutant" means biochemical oxygen
demand, suspended solids, pH and fecal coliform bacteria,
plus additional pollutants identified in the NPDES permit,
if the publicly owned treatment works was designed to treat
such pollutants, and, in fact, does remove such pollutants
to a substantial degree. Examples of such additional
pollutants may include.
chemical oxygen demand
total organic carbon
phosphorus and phosphorus compounds
nitrogen and nitrogen compounds
fats, oils, and greases of animal or vegetable
origin except as defined below in Prohibited
Wastes.
Incompatible Pollutant
The term "incompatible pollutant" means any pollutant which
is not a compatible pollutant as defined above.
Joint Treatment works
Publicly owned treatment works for both non-industrial and
industrial wastewater.
Major Contributing Industry
A major contributing industry is an industrial user of the
publicly owned treatment works that: has a flow of 189.2
cubic meters (50,000 gallons) or more per average work day;
has a flow greater than five percent of the flow carried by
the municipal system receiving the waste; has, in its waste,
a toxic pollutant in toxic amounts as defined in standards
issued under Section 307 (a) of the Act; or is found by the
828
-------
permit issuance authority, in connection with the issuance
of an NPDES permit to the publicly owned treatment works
receiving the waste, to have significant impact, either
singly or in combination with other contributing industries,
on that treatment works or upon the quality of effluent from
that treatment works.
pretreatment
Treatment of wastewaters from sources before introduction
into the publicly owned treatment works.
Prohibited Wastes
No waste introduced into a publicly owned treatment works
shall interfere with the operation or performance of the
works. Specifically, the following wastes shall not be
introduced into the publicly owned treatment works:
a. Wastes which create a fire or explosion hazard in
the publicly owned treatment works;
b. wastes which will cause corrosive structural damage
to treatment works, but in no case wastes with a pH
lower than 5.0, unless the works are designed to
accommodate such wastes;
c. Solid or viscous wastes in amounts which would
cause obstruction to the flow in sewers, or other
interference with the proper operation of the
publicly owned treatment works; and
d. Wastes at a flow rate and/or pollutant discharge
rate which is excessive over relatively short time
periods so that there is a treatment process upset
and subsequent loss of treatment efficiency.
Pretreatment for incompatible Pollutants
In addition to the above, the pretreatment standard for
incompatible pollutants introduced into a publicly owned
treatment works by a major contributing industry shall be
best practicable control technology currently available;
provided that, if the publicly owned treatment works which
receives the pollutants is committed, in its KPDES permit,
to remove a specified percentage of any incompatible
pollutant, the pretreatment standard applicable to users of
such treatment works shall be correspondingly reduced for
that pollutant; and provided further that the definition of
829
-------
best practicable control technology currently available for
industry categories may be segmented for application to
pretreatment if the Administrator determines that the
definition for direct discharge to navigable waters is not
appropriate for industrial users of joint treatment works.
Recommended Pretreatment Guidelines
In accordance with the preceding Pretreatment Standards for
Municipal Sewer Works, the following are recommended for
Pretreatment Guidelines for the wastewater effluents:
a. No pretreatment is required for removal of
compatible pollutants. In addition to the list of
compatible pollutants in the above paragraphs,
total organic carbon, and chemical oxygen demand
were found to be compatible for this industry.
b. Suspended-solids, at the high concentrations often
found in untreated effluent from point sources
within this industrial category, effectively
constitute an incompatible pollutant. Many of the
wastewaters encountered in this study require
settling or sedimentation to lower the
suspended-solids levels to 500 mg/1 or less prior
to conveyance to a publicly owned treatment works.
c. Pollutants such as phosphorus and phosphorus com-
pounds; nitrogen and nitrogen compounds; and fats,
oils, and greases need not be removed, provided
that the publicly owned treatment works were
designed to treat such pollutants and will accept
them. Otherwise, levels should be at or below the
recommendation period for BPCTCA.
d. A pH range of 6 to 9 is desirable for wastewater
treatment by biological methods.
e. Hazardous pollutants such as cyanides, chromates,
heavy metals, and other substances which would
interfere with microorganisms responsible for
organic-substance degradation in a treatment
facility should be restricted to those quantities
recommended in Section ix Guidelines for Best
Practicable Control Technology Currently Available.
830
-------
Most of the mining and milling operations are located in
isolated, rural regions and have no access to municipal
treatment facilities.
In addition, the hydraulic loading to the treatment systems
should be as uniform as possible to maximize treatment
efficiency; therefore, the large volumes and high seasonal
discharges encountered in the ore mining and dressing
industry may have adverse effects upon treatment
efficiencies.
In the relatively few instances where municipal treatment
systems may be used because of proximity, it may be
necessary to use chemical treatment and settling, pH
control, and flow equalization or regulation.
831
-------
SECTION XII
ACKNOWLEDGEMENTS
This document was developed primarily from contractor's
draft reports prepared by Calspan corporation. The staff at
Calspan, under the supervision of Dr. P. Michael TerlecJcy,
are gratefully acknowledged for their invaluable assistance
in field investigation, water sample analysis, and the
preparation of the draft reports.
Appreciation is extended to the following trade associations
and individual cooperations for assistance and cooperation
during the course of this program:
Aluminum Association
American Iron Ore Association
American Mining Congress
Aluminum Company of America
Amax Lead Company of Missouri
American Exploration and Mining Company
American Smelting and Refining Company
Anaconda Company
Atlas Corporation
Bethlehem Mines Corporation
Brush Wellman Company
Bunker Hill Company
Carlin Gold Mining Company
Cities Service Company
Cleveland-Cliffs iron Company
Climax Molybdenum Company
Cominco American, Inc.
Continental Materials Corporation
Copper Range company
Curtis Nevada Mines, Inc.
Cyprus-Bagdad Copper Corporation
Eagle Pitcher Industries, Inc.
E.I. duPont de Nemours and Company, Inc.
Erie Mining Company
Goodnews Bay Mining Company
Hanna Mining Company
Homestake Mining Company
Idarado Mining Company
Inspiration Consolidated Copper Company
Jones and Laughlin Steel Corporation
Kennecot copper Corporation
Kerramerican, Inc.
833
-------
Kerr McGee Corporation
Knob Hill Mines, Inc.
Magma Copper Company
Marguette Iron Mining Company
Molybdenum Corporation of America
National Lead Industries, Inc.
New Jersey Zinc Company
Oat Hill Mining Company
Olgleby-Norton Company - Eveleth Taconite
Phelps Dodge Corporation
Pickands Mather and Company - Erie Mining Company
Ranchers Exploration and Development Corporation
Rawhide Mining Company
Reynolds Mining Corporation
Standard Metals corporation
St. Joe Minerals Company
Sunshine Mining Company
Titanium Enterprises, Inc.
Union Carbide Corporation
United Nuclear Corporation
U.S. Antimony Corporation
U.S. Steel Corporation
834
-------
SECTION XIII
REFERENCES
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Ohio, 1973.
2. Minerals Yearbook, Bureau of Nines, U.S. Department of
the Interior, Washington, 1972.
3. "Metals Statistics," American Metal Market, Fairchild
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4. "Mineral Supply Bulletin," Mineral Industrial Surveys,
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5. "Active Alaskan Placer Operations, 1975," R.D. Carnes,
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835
-------
14. "Manganese from Low Grade Ores by the Ammonium Carbonate
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15. The Mining of Nickel, J.R. Boldt and P. Quieneau, D. Van
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19. Technical Information on the Climax Property, Climax
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24. "State-of-the-Art of Uranium Mining, Milling, and
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1974.
25. "Copper Leaching Practices in the Western United
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26. "Copper in the United States - A Position Survey," J.V.
Beall, Mining Engineering, pp. 35-47, April 1973.
836
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27. Mineral Processing, E.J. Pryor, Elsevier Publishing Co.,
Ltd., New York, 1965.
28. "Reagent Control in Flotation," C. H.G. Bushell and N.
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29. "Polarographic Determination of Xanthates in Flotation
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30. "Rehabilitation Potential of Western coal Lands,"
National Academy of Sciences, 1974.
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EPS 8-WP-73-1, Water Pollution Control Directorate,
Environment Canada, Ottawa (Ont.), Canada, June 1973.
32. "The Solubility of Heavy Metal Hydroxides in Water,
Sewage, and sewage Sludge - I, the Solubility of Some
Metal Hydroxides," S.H. Jenkins, D.G. Keight, and R.E.
Humphrey, Journal on Air and Water Pollution, No. 8, pp.
537-556, 1964.
33. "Processes, Procedures, and Methods to Control Pollution
from Mining Activities," U.S. Environmental Protection
Agency, Washington, EPA-430/9-73-Oil, 1973.
34. "Development Document for Proposed Effluent Limitation
Guidelines and New Source Performance Standards for the
Primary Copper Smelting Subcategory and the Primary
Copper Refining Subcategory of the Copper Segment of the
Non Ferrous Metals Manufacturing Point Source Category,"
U.S. Environmental Protection Agency, Washington, EPA-
440/1-74-032b, November 1974.
35. "Case History, Non Ferrous Metal Mining - Smelting
Industry, Process wastewater Treatment at Bunker Hill
Co.," G.M. Baker, A.H. Larsen, Paper presented at AMC
Mining Convention, September 9-12, 1973, Denver,
Colorado.
36. "Northeastern New Brunswick Mine Water Quality Program,"
Montreal Engineering Company, LTD, Frederickton, New
Brunswick, Canada, 1972.
37. "Wastewater Treatment Technology," J.W. Patterson et 41,
Illinois Institute for Environmental Quality, Chicago,
Illinois, August, 1971.
837
-------
38. "Mercury Recovery from Contaminated Waste Water and
Sludges,11 U.S. Environmental Protection Agency,
Washington, EPA-660/2-74-086, December 1974.
39. "Transport and The Biological Effects of Molybdenum in
the Environment, Progress Report to N.S.F." W.R.
Chappell (The Molybdenum Project, University of
Colorado, Boulder, December 1971).
40. "Removal of Dissolved Molybdenum from Industrial
Wastewaters by Ferric Oxyhydroxide," Bary R. LeGendre
and D.D. Runnels, Dept. of Geological Sciences,
University of Colorado, Boulder, Colorado, September 1,
1974.
41. "Transport and Biological Effects of Molybdenum in the
Environment, Progress Report to N.S.F." W.R. Chappell
(The Molybdenum Project University of Colorado, Boulder,
January 1973).
42. "Suggested Method for Vanadate Removal from Mill
Effluents," J.G. Michalovic, J.G* Fisher, and D.H. Bock,
Calspan Corporation Internal Memorandum to P.M.
Terlecky, dated 27 May, 1976, also Journal Environmental
Science Health, A12 (162), 21-27 (1977).
43. "Neutradesulfating Treatment Process for Acid Mine
Drainage," Catalytic, Inc., EPA-14010-DYH-12/71, 1971.
**• Water and Wastewater Engineering. Volume 2, G.M. Fair,
J.C. Geyer, J.C. Prun, John Wiley & Sons, New York,
1968.
45. "Traces of Heavy Metals in Water Removal Processes and
Monitoring," U.S. Environmental Protection Agency,
Washington, EPA-902/9-74-001, 1974.
46. "Precipitation Scavenging of Inorganic Pollutants from
Metropolitan sources," Battelle-Pacific, NW
Laboratories, EPA-650/3-74-005, 1974.
47. "Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the
Smelting and Slag Processing Segments of the Ferroalloy
Manufacturing Point Source Category," U.S. Environmental
Protection Agency, Washington, EPA-440/l-74-008a,
February 1974.
838
-------
48. "Methods to Treat, Control and Monitor Spilled Hazardous
Materials, " Monthly Progress Report No. 6, EPA Contract
68-01-0110, Calspan Corporation, Buffalo, New York,
December 1971.
49. "An Investigation of Techniques for Removal of chromium
from Electroplating Wastes," Battelle Memorial
Institute, EPA-12010-EIE-03/71, 1971.
50. "Adsorption/Filtration Plant Cuts Phenols From
Effluent," J.B. Henshaw, Chemical Engineering. May 31,
1971.
51. "Treatment of Ferrous Acid Mine Drainage with Activated
Carbon," C.T. Ford and J.F. Boyer, Jr., D.S.
Environmental Protection Agency, Washington, EPA-R2-73-
150, 1973.
52. "Removal of Dissolved contaminants from Mine Drainage,"
J.P. Miller, U.S. Environmental Protection Agency,
Washington, EPA-R2-72-130, 1972.
53. "Waste Wool as a Scavenger for Mercury Pollution in
Waters," J.P* Tratnyek, U.S. Environmental Protection
Agency, Washington, EPA-16080-HUB-02/72, 1972.
54. Water Treatment, G.V. James, Technical Press, Ltd.,
1965.
55. "Peat Moss Bed Filtration Removes Heavy Metals from
Wastewaters," Environmental Science and Technology. Vol.
8, NO. 598, 1974.
56. "Adsorption of Hg (II) by Hydrous Manganese Oxides,"
R.A. Lockwood and K.Y. Chen, Environmental Science and
Technology, Vol. 7, No. 1028, 1973.
57 "Study of Reutilization of Wastewater Recycled through
Groundwater," D.F. Boen, et_ al_., U.S. Environmental
Protection Agency, Washington, EPA-16060-DDZ-07/71,
1971.
58. "Process Design Manual for Sludge Treatment and
Disoosal." U.S. Environmental Protection Agency,
Technology Transfer Office, Washington, EPA-625/l-7«-
006, 1974.
59 Ion Exchange Technology, F.C. Nachod and J. Schubert,
" Academic Press, Inc., New York, 1956.
839
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60. "Application of Reverse Osmosis to Acid Mine Drainage
Treatment,** R.C. wilmoth, U.S. Environmental Protection
Agency, Washington, EPA-670/2-73-100, December 1973.
61. "Evaluation of Ion Exchange Processes for Treatment of
Mine Drainage waters," Office of Saline Water, Envirex,
Inc., Milwaukee, Wisconsin, PB-227734, January 197U.
62. "Mine Drainage Pollution Control via Reverse osmosis,'*
R.C. Wilmoth and R.D. Hill, Mining Engineering, pp. 45-
47, March 1973.
63. "Development of a High Product Mater Recovery System for
the Treatment of Acid Mine Drainage by Reverse Osmosis,"
M.K. Gupta, Office of Saline Water, Envirex, Inc.,
Milwaukee, Wisconsin, 1974.
64. "The Use, Characteristics, and Toxicity of Mine-Mill
Reagents in the Province of Ontario," J.R. Hawley,
Ontario Ministry of the Environment, Toronto, Canada,
1972.
65. "Liquid-Liquid Solvent Extraction in the Mineral Indus-
tries," J.O. Golden, Mineral Industries Bulletin, March
1973.
66. "Metallurgical Application of Solvent Extraction," J.B.
Rosenbaum, et al.. Bureau of Mines, U.S. Department of
the Interior, Washington, Information Circular 8502,
1971.
67. "Solvent Extraction," C. Hanson, Chemical Engineering..
August 26, 1968.
68. "Multi-stage Flash Evaporation System for the Purifi-
cation of Acid Mine Drainage,11 D.R. Maneval and S.
Lemezis, Proceedings of society of Mining Engineers.AIMS
Fall Meeting, 1970.
69. "Base Metal Mine Waste Management in Northeastern New
Brunswick," Montreal Engineering Company, Ltd., Freder-
ickton, N.B., Canada, EPS 8-WP-73-1, June 1973.
70. "Report on Lead and Zinc Ores," to Calspan Corporation,
B.G. Wixson, C.J. Jennett, and M.G. Bardie, University
of Missouri at Rolla, Missouri, August 1974.
840
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71. "Operational Experience with a Base Metal Mine Drainage
Pilot Plant," Technology Development Report EPS 4-WP74-
8, Environment Canada, Environmental Protection Service,
water Pollution Control Directorate, Ottawa, Ontario,
Canada, September 1974.
72. "The Problem of Acid Mine Drainage in the Province of
Ontario,11 J.R. Hawley, Ministry of the Environment,
Toronto, Ontario, Canada, 1972.
73. "Effects of Recycling Mill Water in the New Lead Belt of
Southeast Missouri," P.H. Sharp and K.L. Clifford,
Proceedings of AIMS Meeting, Chicago, Illinois, February
26, 1973.
74. Data from Colorado School of Mines Research Institute,
Project J31120, October 15, 1974.
75. "A Study of Waste Generation, Treatment and Disposal in
the Metals Mining Industry," Final Report prepared for
U.S. Environmental Protection Agency, Midwest Research
Institute, Kansas City, Missouri, October 1976.
76. "The Development of National Waste Water Regulations and
Guidelines for the Mining Industry," CIM Bulletin.
November 1974.
841
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SECTION XIV
GLOSSARY
absorption - The process by which a liquid is drawn into and
tends to fill permeable pores in a porous
solid body; also the increase in weight of a
porous solid body resulting from the penetra-
tion of liquid into its permeable pores.
acid copper -
acid cure -
Copper elect rode posited from an acid solution
of a copper salt, usually copper sulfate.
In uranium extraction, sulfation of moist ore
before leach.
acid leach - (a) Metallurgical process for dissolution of
values by means of acid solution (used on
sandstone ores of low lime content); (b) In
the copper industry, a technology employed to
recover copper from low grade ores and mine
dump materials when oxide (or mixed oxide-
sulfide, or low grade sulfide) mineralization
is present, by dissolving the copper minerals
with either sulfuric acid or sulfuric acid
containing ferric iron. Four methods of
leaching are employed: dump, heap, in-situ,
and vat (see appropriate definitions).
acid mine
water - (a) Mine water which contains free
sulfuric acid, mainly due to the weathering of
iron pyrites; (b) Where sulfide minerals break
down under the chemical influence of oxygen
and water, the mine water becomes acidic and
can corrode ironwork.
activator, activating agent - A substance which when added
to a mineral pulp promotes flotation in the
presence of a collecting agent. It may be
used to increase the floatability of a mineral
in a froth, or to reflect a depressed (sunk
mineral).
adit - (a) A horizontal or nearly horizontal passage driven
from the surface for the working or dewatering
of a mine; (b) A passage driven into a mine
from the side of a hill.
843
-------
adsorption - The adherence of dissolved, colloidal, or
finely divided solids on the surface of solids
with which they are brought into contact.
aeroflocs - Synthetic water-soluble polymers used as floccu-
lating agents.
all sliming - (a) Crushing all the ore in a mill to so fine
a state that only a small percentage will fail
to pass through a 200-mesh screen; (b) Tern
used for treatment of gold ore which is ground
to a size sufficiently fine for agitation as a
cyanide pulp, as opposed to division into
coarse sands for static leaching and fine
slimes for agitation.
alluminothermic process - The reduction of oxides in an exo-
thermic reaction with finely divided aluminum.
alluvial deposit; placer deposit - Earth, sand, gravel or
other rock or mineral materials transported by
and laid down by flowing water. Alluvial
deposits generally take the form of (1) sur-
face deposits; (2) river deposits; (3) deep
leads; and (4) shore deposits.
alunite - A basic potassium aluminum sulfate,
KA13(OH)6(SO4)2. Closely resembles kaolinite
and~"bccurs in similar locations.
amalgamation - The process by which mercury is alloyed with
some other metal to produce amalgam. It was
used extensively at one time for the
extraction of gold and silver from pulverized
ores, now is largely superseded by the cyanide
process.
AN-FO - Ammonium nitrate - fuel oil blasting agents.
asbestos minerals - Certain minerals which have a fibrous
structure, are heat resistant, chemically
inert and possessing high electrical insulat-
ing qualities. The two main groups are
serpentine and amphiboles. Chrysotile
(fibrous serpentine, 3MgO . 2SiO2 . 2H2O) is
the principal commercial variety. ~" other
commercial varieties are amosite, crocidolite,
actinolite, anthophyllite, and tremolite.
844
-------
azurite - A blue carbonate of copper, Cu!(CO3)2(OH) 2,
crystallizing in the monoclinic system.~ Found
as an alteration product of chalcopyrite and
other sulfide ores of copper in the upper
oxidized zones of mineral veins.
bastnasite; bastnaesite - A greasy, wax-yellow to reddish-
brown weakly radioactive mineral,
(Ce,La) (CO3J F, most commonly found in contact
zones, less" often in pegmatites.
bauxite - (a) A rock composed of aluminum hydroxides, essen-
tially A1203 . 2H20. The principal ore of
aluminum;"also used collectively for lateritic
aluminous ores. (b) Composed of aluminum
hydroxides and impurities in the form of free
silica, clay, silt, and iron hydroxides. The
primary minerals found in such deposits are
boehmite, gibbsite, and diaspore.
Bayer Process - Process in which impure aluminum in bauxite
is dissolved in a hot, strong, alkalai solu-
tion (normally NaOH) to form sodium aluminate.
Upon dilution and cooling, the solution hydro-
lyzes and forms a precipitate of aluminum
hydroxide.
bed - The smallest division of a stratified series and
marked by a more or less well-defined
divisional plane from the materials above and
below.
beneficiation - (a) The dressing or processing of ores for
the purpose of (1) regulating the size of a
desired product, (2) removing unwanted
constituents, and (3) improving the quality,
purity, assay grade of a desired product; (b)
Concentration or other preparation of ore for
smelting by drying, flotation, or magnetic
separation.
Best Available Technology Economically Achievable - The
level of technology applicable to effluent
limitations to be achieved by July 1, 1983,
for industrial discharges to surface waters as
defined by Section 301 (b)(1) (A) of the Act.
Best Practicable Control Technology Currently Available -
The level of technology applicable to effluent
das
-------
limitations to be achieved by July 1, 1977,
for industrial discharges to surface waters as
defined by Section 301 (b)(1) (A) of the Act.
byproduct - A secondary or additional product.
carbon absorption - A process utilizing the efficient
absorption characteristics of activated carbon
to remove both dissolved and suspended
substances,
camotite - A bright yellow uranium mineral, K2(UO2) 2(VO4) 2
• 3H20.
cationic collectors - In flotation, amines and related
organic compounds capable of producing
positively charged hydrocarbon-bearing ions
for the purpose of floating miscellaneous
minerals, especially silicates.
cationic reagents - In flotation/ surface active substances
which have the active constituent in the posi-
tive ion. Used to flocculate and to collect
minerals that are not flocculated by the rea-
gents/ such as oleic acid or soaps, in which
the surface-active ingredient is the negative
ion.
cement copper - Copper precipitated by iron from copper
sulfate solutions.
cerium metals - Any of a group of rare-earth metals
separable as a group from other metals
occurring with them and in addition to cerium
includes lanthanum, praseodymium, neodymium,
promethium, samarium and sometimes europium.
cerium minerals - Rare earths; the important one is
monazite.
chalcocite - Copper sulfide, Cu2S.
chalcopyrite - A sulfide of copper and iron, CuFeS2.
chert - Cryptocrystalline silica, distinguished from flint
by flat fracture, as opposed to conchoidal
fracture.
chromite - Chrome iron ore, FeCr20£.
846
-------
chrysocolla - Hydrated copper silicate, CuSiO.3 . 2H2JO,
chrysotile - A metamorphic mineral, an asbestos, the fibrous
variety of serpentine. A silicate of
magnesium, with silica tetrahedra arranged in
sheets.
cinnabar - Mercury sulfide, HgS.
claim - The portion of mining ground held under the Federal
and local laws by one claimant or association,
by virtue of one location and record. A claim
is sometimes called a •location'.
clarification - (a) The cleaning of dirty or turbid liquids
by the removal of suspended and colloidal
matter; (b) The concentration and removal of
solids from circulating water in order to
reduce the suspended solids to a minimum; (c)
In the leaching process, usually from pregnant
solution, e.g., gold-rich cyanide prior to
precipitation.
classifier - (a) A machine or device for separating the con-
stituents of a material according to relative
sizes and densities thus facilitating concen-
tration and treatment. Classifiers may be
hydraulic or surface-current box classifiers.
Classifiers are also used to separate sand
from slime, water from sand, and water from
slime; (b) The term classifier is used in
particular where an upward current of water is
used to remove fine particles from coarser
material; (c) In mineral dressing, the
classifier is a device that takes the ball-
mill discharge and separates it into two
portions—the finished product which is ground
as fine as desired, and oversize material.
coagulation
- The binding of individual particles to form
floes or agglomerates and thus increase their
rate of settlement in water or other liquid
(see also flocculate).
coagulator - A soluble substance, such as lime, which when
added to a suspension of very fine solid
particles in water causes these particles to
adhere in clusters which will settle easily.
847
-------
Used to assist in
flotation.
reclaiming water used in
collector -
A heteropolar compound containing a hydrogen-
carbon group and an ionizing group, chosen for
the ability to adsorb selectively in froth
flotation processes and render the adsorbing
surface relatively hydrophobia. A promoter.
columbite; tantalite; niobite - A natural oxide of niobium
(columbium), tantalum, ferrous iron, and
manganese, found in granites and pegmatites,
(Fe,Mn) (Nb,Ta)2O£.
concentrate - (a) In mining, the product of concentration;
(b) To separate ore or metal from its contain-
ing rock or earth; (c) The enriched ore after
removal of waste in a beneficiation mill, the
clean product recovered in froth flotation.
concentration - Separation and accumulation of economic min-
erals from gangue.
concentrator - (a) A plant where ore is separated into
values (concentrates) and rejects (tails). An
appliance in such a plant, e.g., flotation
cell, jig, electromagnet, shaking table. Also
called mill; (b) An apparatus in which, by the
aid of water or air and specific gravity,
mechanical concentration of ores is performed.
conditioners - Those substances added to the pulp to
maintain the proper pH to protect such salts
as NaCH, which would decompose in an acid
circuit, etc. Na2C
-------
The zone of primary sulfides (relatively low
in grade) includes the unaltered minerals
L, — J •- .^ ^ ^_ ft — * T • *
crusher -
The zone of
in grade) includes the unaltered minerals
bornite and chalcopyrite.
A. machine for crushing rock or other materials.
Among the various types of crushers are the
ball-mill, gyratory crusher, Hadsel mill,
hammer mill, jaw crusher, rod mill, rolls,
stamp mill, and tube mill. cuprite - A
secondary copper mineral, Cu2O.
cyanidation - A process of extracting gold and silver as
cyanide slimes from their ores by treatment
with dilute solutions of potassium cyanide and
sodium cyanide.
cyanidation vat - A large tank, with a filter bottom, in
which sands are treated with sodium cyanide
solution to dissolve out gold.
cyclone - (a) The conical-shaped apparatus used in dust
collecting operations and fine grinding appli-
cations; (b) A classifying (or concentrating)
separator into which pulp is fed, so as to
take a circular path. Coarser and heavier
fractions of solids report at the apex of long
cone while finer particles overflow from cen-
tral vortex.
daughter - Decay product formed when another
undergoes radioactive disintegration.
element
decant structure - Apparatus for removing clarified water
from the surface layers of tailings or
settling ponds. Commonly used structure
include decant towers in which surface waters
flow over a gate (adjustable in height) and
down the tower to a conduit generally buried
beneath the tailings, decant weirs over which
water flows to a channel external to the
tailings pond, and floating decant barges
which pump surface water out of the pond.
dense-media separation - (a) Heavy media separation, or sink
float. Separation of heavy sinking from lignt
floating mineral particles in a fluid of
intermediate density; (b) Separation of
relatively light (floats) and heavy ore
849
-------
par-tides (sinks), by immersion in a
intermediate density.
bath of
Denver cell
Denver
jig
- A flotation cell of the subaeration type, in
wide use. Design modifications include
recededdisk, conical-disk, and multibladed
impellers, low-pressure air attachments, and
special froth withdrawal arrangements.
- Pulsion-suction diaphragm jig for fine
material, in which makeup (hydraulic) water is
admitted through a rotary valve adjustable as
to portion of jigging cycle over which
controlled addition is made.
deposit - Mineral or ore deposit is used to designate a
natural occurrence of a useful mineral or an
ore, in sufficient extent and degree of
concentration to invite exploitation.
depressing
agent; depressor - In the froth flotation
process, a substance which reacts with the
particle surface to render it less prone to
stay in the froth, thus causing it to wet down
as a tailing product (contrary to activator).
detergents, synthetic - Materials which have a cleansing
action like soap but are not derived directly
from fats and oils. Used in ore flotation.
development work - Work undertaken to open up ore bodies as
distinguished from the work of actual ore
extraction or exploratory work.
dewater - To remove water from a mine usually by pumping,
drainage or evaporation.
differential flotation - Separating a complex ore into two
or more valuable minerals and gangue by flo-
tation; also called selective flotation. This
type of flotation is made possible by the use
of suitable depressors and activators.
discharge - Outflow from a pump, drill hole, piping system,
channel, weir or other discernible, confined
or discrete conveyance (see also point
source).
850
-------
dispersing agent - Reagent added to flotation circuits to
prevent flocculation, especially of objection-
able colloidal slimes. sodium silicate is
frequently added for this purpose.
dredge; dredging - A large floating contrivance for
underwater excavation of materials using
either a chain of buckets, suction pumps, or
other devices to elevate and wash alluvial
deposits and gravel for gold, tin, platinum,
heavy minerals, etc.
dressing - Originally referred to the picking, sorting, and
washing of ores preparatory to reduction. The
term now includes more elaborate processes of
milling and concentration of ores.
drift mining - A term applied to working alluvial deposits
by underground methods of mining. The
paystreak is reached through an adit or a
shallow shaft, wheelbarrows or small cars may
be used for transporting the gravel to a
sluice on the surface.
dump leaching - Term applied to dissolving and recovering
minerals from subore-grade materials from a
mine dump. The dump is irrigated with water,
sometimes acidified, which percolates into and
through the dump, and runoff from the bottom
of the dump is collected, and a mineral in
solution is recovered by chemical reaction.
Often used to extract copper from low grade,
waste material of mixed oxide and sulfide
mineralization produced in open pit mining.
effluent - The wastewater discharged from a point source to
navigable waters.
eleetrowinning - Recovery of a metal from an ore* by means of
electrochemical processes, i.e., deposition of
a metal on an electrode by passing electric
current through an electrolyte.
eluate - Solutions resulting from regeneration (elation) of
ion exchange resins.
eluent - A solution used to extract collected ions from an
ion exchange resin or solvent and return the
resin to its active state.
651
-------
exploration - Location of the presence of economic deposits
and establishing ther nature, shape, and grade
and the investigation may be divided into (1)
preliminary and (2) final.
extraction - (a) The process of mining and removal of ore
from a mine. (b) The separation of a metal or
valuable mineral from an ore or concentrate.
(c) Used in relation to all processes that are
used in obtaining metals from their ores.
Broadly, these processes involve the breaking
down of the ore both mechanically (crushing)
and chemically (decomposition), and the
separation of the metal from the associated
gangue.
ferruginous - containing iron.
ferruginous chert - A sedimentary deposit consisting of
chalcedony or of fine-grained quartz and
variable amounts of hematite, magnetite, or
limonite.
ferruginous deposit - A sedimentary rock containing enough
iron to justify exploitation as iron ore. The
iron is present, in different cases, in
silicate, carbonate, or oxide form, occurring
as the minerals chamosite, thuringite,
siderite, hematite, limonite, etc.
flask - A unit of measurement for mercury; 76 pounds.
flocculant - An agent that induces or promotes flocculation
or produces floccules or other aggregate
formation, especially in clays and soils.
flocculate - To cause to aggregate or to coalesce into small
lumps or loose clusters, e.g., the calcium ion
tends to flocculate clays.
flocculating agent; flocculant - A substance which produces
f loccu lati on *
flotation - The method of mineral separation in which a
froth created in water by a variety of
reagents floats some finely crushed minerals,
whereas other minerals sink.
852
-------
flotation agent - A substance or chemical which alters the
surface tension of water or which makes it
froth easily. The reagents used in the flo-
tation process include pH 'regulators, slime
dispersants, resurfacing agents, wetting
agents, conditioning agents, collectors, and
frothers.
friable - Easy to break, or crumbling naturally.
froth, foam .- In the flotation process, a collection of
bubbles resulting from agitation, the bubbles
being the agency for raising (floating) the
particles of ore to the surface of the cell.
frother(s) - Substances used in flotation processes to make
air bubbles sufficiently permanent principally
by reducing surface tension. Common frothers
are pine oil, creyslic acid, and amyl alcohol.
gangue - Undesirable minerals associated with ore.
glory hole - A funnel-shaped excavation, the bottom of which
is connected to a raise driven from an under-
ground haulage level or is connected through a
horizontal tunnel (drift) by which ore may
also be conveyed.
gravity separation - Treatment of mineral particles which
exploits differences between their specific
gravities. Their sizes and shapes also play a
minor part in separation. Performed by means
of jigs, classifiers, hydrocyclones, dense
media, shaking tables, Humphreys spirals,
sluices, vanners and briddles.
grinding - (a) Size reduction, into relatively fine
particles. (b) Arbitrarily divided into dry
grinding performed on mineral containing only
moisture as mined, and wet grinding, usually
done in rod, ball or pebble mills with added
water. ' ... • .::.. '_..',, -\ .. ...', \L
heap leaching - A process used in the recovery of copper
from weathered ore and material from mine
dumps. The liquor seeping through the beds is
led to tanks, where it is treated with scrap
iron to precipitate the copper from solution.
853
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This process can also be applied to the sodium
sulfide leaching of mercury ores.
heavy-media separation - See dense-media separation.
hematite - One of the most common ores of iron, Fe2!03, which
when pure contains about 70% metallic iron and
30% oxygen. Most of the iron produced in
North America comes from the iron ranges of
the Lake Superior District, especially the
Mesabi Range, Minnesota. The hydrated variety
of this ore is called limonite.
Huntington-Heberlein Process - A sink- float process
employing a galena medium and utilizing froth
flotation as the means of medium recovery.
hydraulic mining - (a) Mining by washing sand and soil away
with water which leaves the desired mineral.
(b) The process by which a bank of gold-bear-
ing earth and rock is excavated by a jet of
water, discharged through the converging
nozzle of a pipe under great pressure. The
debris is carried away with the same water and
discharged on lower levels into watercourses
below.
hydrolysate; hydrolyzate - A sediment consisting partly of
chemically unde composed, finely ground rock
powder and partly of insoluble matter derived
from hydrolytic decomposition during
weathering.
hydrometallurgy - The treatment of ores, concentrates, and
other metal-bearing materials by wet
processes, usually involving the solution of
some component, and its subsequent recovery
from the solution.
ilmenite - An iron-black mineral, FeO . TiO^. Resembles
magnetite in appearance but is readily dis-
tinguished by feeble magnetic character.
in-situ leach - Leaching of broken ore in the subsurface as
it occurs, usually in abandoned underground
mines which previously employed block-caving
mining methods.
854
-------
ion(ic) exchange - The replacement of ions on the surface,
or sometimes within the lattice, of materials
such as clay.
iron formation - Sedimentary, low grade, iron ore bodies
consisting mainly of chert and fine-grained
quartz and ferric oxide segregated in bands or
sheets irregularly mingled (see also
taconite).
jaw crusher - A primary crusher designed to reduce large
rocks or ores to sizes capable of being
handled by any of the secondary crushers.
jig - A machine in which the feed is stratified in water by
means of a pulsating motion and from which the
stratified products are separately removed,
the pulsating motion being usually obtained by
alternate upward and downward currents of the
water.
jigging - (a) The separation of the heavy fractions of an
ore from the light fractions by means of a
jig. (b) Up and down motion of a mass of
particles in water by- means of pulsion.
laterite - Red residual soil developed in
humid, tropical, and subtropical regions of
good drainage. It is leached of silica and
contains concentrations particularly of iron
oxides and hydroxides and aluminum hydroxides.
It may be an ore of iron, aluminum, manganese,
or nickel.
launder - (a) A trough, channel, or gutter usually of wood,
by which water is conveyed; specifically in
mining, a chute or trough for conveying pow-
dered ore, or for carrying water to or from
the crushing apparatus. (b) A flume.
leaching - (a) The removal in solution of the more soluble
minerals by percolating waters. (b) Extract-
ing a soluble metallic compound from an ore by
selectively dissolving it in a suitable
solvent, such as water, sulfuric acid, hydro-
chloric acid, etc. The solvent is usually
recovered by precipitation of the metal or by
other methods.
855
-------
leach ion-exchange flotation process - A mixed method of
extraction developed for treatment of copper
ores not amenable to direct flotation. The
metal is dissolved by leaching, for example,
with sulfuric acid, in the presence of an ion
exchange resin. The resin recaptures the
dissolved metal and is then recovered in a
mineralized froth by the flotation process.
leach precipitation float - A mixed method of chemical reac-
tion plus flotation developed for such copper
ores as chrysocolla and the oxidized minerals.
The value is dissolved by leaching with acii,
and the copper is reprecipitated on finely
divided particles of iron, which are then
recovered by flotation, yielding an impure
concentrate in which metallic copper predomi-
nates.
lead minerals - The most important industrial one is galena
(PbS), which is usually argentiferous. In the
upper parts of deposits the mineral may be
altered by oxidation to cerussite (Pbco3) or
anglesite (PbSOOJ. Usually galena occurs in
intimate association with sphalerite (ZnS).
leucoxene - A brown, green, or black variety of sphene or
titanite, CaTiSiO_, occurring as monoclinic
crystals. An earthy alteration product con-
sisting in most instances of rutile; used in
the production of titanium tetrachloride.
lime - Quicklime (calcium oxide) obtained by calcining lime-
stone or other forms of calcium carbonate.
Loosely used for hydrated lime (calcium
hydroxide) and incorrectly used for pulverized
or ground calcium carbonate in agricultural
lime and for calcium in such expressions as
carbonate of lime, chloride of lime, and lime
feldspar.
lime slurry - A form of calcium hydroxide in aqueous suspen-
sion that contains considerable free water.
limonite - Hydrous ferric oxide, FeO(OH) . nH2C. An
important ore of iron, occurring in
stalactitic, mammillary, or earthy forms of a
dark brown color, and as a yellowish-brown
856
-------
powder. The chief constituent of bog iron
ore.
liquid-liquid extraction, solvent extraction - A process in
which one or more components are removed from
a liquid measure by intimate contact with a
second liquid, which is itself nearly
insoluble in the first liquid and dissolves
the impurities and not the substance that is
to be purified.
lode - A tabular deposit of valuable mineral between
definite boundaries. lode, as used by miners,
is nearly synonymous with the term vein as
employed by geologists.
magnetic separation - The separation of magnetic materials
from nonmagnetic materials using a magnet. An
important process in the beneficiation of iron
ores in which the magnetic mineral is
separated from nonmagnetic material, e.g.,
magnetite from other minerals, roasted pyrite
from sphalerite.
magnetic separator - A device used to separate magnetic from
less magnetic or nonmagnetic materials. The
crushed material is conveyed on a belt past a
magnet.
magnetite, magnetic iron ore - Natural black oxide of iron,
Fe3O4. As black sand, magnetite occurs in
placer deposits, and also as lenticular bands.
Magnetite is used widely as a suspension solid
in dense-medium washing of coal and ores.
malachite - A green, basic cupric carbonate, Cu2(OH)2CO3,
crystallizing in the monoclinic system. It is
a common ore of copper and occurs typically in
the oxidation zone of copper deposits.
manganese minerals - Those in principal production are pyro-
lusite, some psilomelane, and wad (impure
mixture of manganese and other oxides).
manganese nodules - The concretions, primarily of manganese
salts, covering extensive areas of the ocean
floor. They have a layer configuration and
may prove to be an important source of man-
ganese*
857
-------
manganese ore - A term used by the Bureau of Mines for ore
containing 35 percent or more manganese and
may include concentrate, nodules, or synthetic
ore.
manganiferous iron ore - A term used by the Bureau of Mines
for ores containing 5 to 10 percent manganese.
manganiferous ore - A term used by the Bureau of Mines for
any ore of importance for its manganese con-
tent containing less than 35 percent manganese
but not less than 5 percent manganese.
mercury minerals - The main source is cinnabar, HgS.
mill - (a) Reducing plant where ore is concentrated and/or
metals recovered. (b) Today the term has been
broadened to cover the whole mineral treatment
plant in which crushing, wet grinding, and
further treatment of the ore is conducted.
(c) In mineral processing, one machine, or a
group, used in comminution.
minable -
(a) Capable of being mined. (b) Material that can
be mined under present day mining technology
and economics.
mine - (a) An opening or excavation in the earth for the
purpose of excavating minerals, metal ores or
other substances by digging. (b) A word for
the excavation of minerals by means of pits,
shafts, levels, tunnels, etc., as opposed to a
quarry, where the whole excavation is open.
In general the existence of a mine is deter-
mined by the mode in which the mineral is
obtained, and not by its chemical or geologic
character. (c) An excavation beneath the
surface of the ground from which mineral
matter of value is extracted. Excavations for
the extraction of ore or other economic
minerals not requiring work beneath the
surface are designated by a modifying word or
phrase as: (1) opencut mine - an excavation
for removing minerals which is open to the
weather; (2) steam shovel mine - an opencut
mine in which steam shovels or other power
shovels are used for loading cars; (3) strip
mine - a stripping, an openpit mine in which
the overburden is removed from the exploited
858
-------
material before the material is taken out; (4)
placer mine - a deposit of sand, gravel or
talus from which some valuable mineral is
extracted; and (5) hydraulic mine - a placer
mine worked by means of a stream of water
directed against a bank of sand, gravel, or
talus. Mines are commonly known by the
mineral or metal extracted, e.g., bauxite
mines, copper mines, silver mines, etc. (d)
Loosely, the word mine is used to mean any
place from which minerals are extracted, or
ground which it is hoped may be mineral
bearing. (e) The Federal and State courts
have held that the word mine, in statutes
reserving mineral lands, included only those
containing valuable mineral deposits. Dis-
covery of a mine: in statutes relating to
mines the word discovery is used: (1) in the
sense of uncovering or disclosing to view ore
or mineral; (2) of finding out or bringing to
the knowledge the existence of ore, or
mineral, or other useful products which were
unknown; and (3) of exploration, that is, the
more exact blocking out or ascertainment of a
deposit that has already been discovered, in
this sense it is practically synonymous with
development, and has been so used in the U.S.
Revenue Act of February 19, 1919 (Sec. 214
subdiv. A10, and Sec. 23ft, subdiv. A9) in
allowing depletion to mines, oil and gas
wells. Article 219 of Income and War Excess
Profits Tax Regulations No. 45, construes
discovery of a mine as: (1) The bona fide
discovery of a commercially valuable deposit
of ore or mineral, of a value materially in
excess of the cost of discovery in natural
exposure or by drilling or other exploration
conducted above or below the ground; and (2)
the development and proving of a mineral or
ore deposit which has been apparently worked
out to be a mineable deposit or ore, or
mineral having a value in excess of the cost
of improving or development.
mine drainage -.. (a) Mine drainage usually implies gravity
flow of water to. a point remote from mining
operation. (b) The process of removing
surplus ground or surface water by artificial
means.
859
-------
mineral - An inorganic substance occurring in nature, though
not necessarily of inorganic origin, which has
(1) a definite chemical composition, or more
commonly, a characteristic range of chemical
composition, and (2) distinctive physical
properties, or molecular structure, with few
exceptions, such as opal (amorphous) and mer-
cury (liquid), minerals are crystalline
solids.
mineral processing; ore dressing; mineral dressing - The dry
and wet crushing and grinding of ore or other
mineral-bearing products for the purpose of
raising concentrate grade; removal of waste
and unwanted or deleterious substances from an
otherwise useful product; separation into
distinct species of mixed minerals; chemical
attack and dissolution of selected values.
modifier(s) - (a) in froth flotation, reagents
used to control alkalinity and to eliminate
harmful effects of colloidal material and
soluble salts. (b) Chemicals which increase
the specific attraction between collector
agents and particle surfaces, or conversely
which increase the wettability of those
surfaces.
molybdenite - The most common ore of molybdenum, MoSz.
molybdenite concentrate - Commercial molybdenite ore after
the first processing operations. Contains
about 90% MoS2 along with quartz, feldspar,
water, and processing oil.
monazite - A. phosphate of the cerium metals and the
principal ore of the rare earths and thorium.
Monoclinic. One of the chief sources of
thorium used in the manufacture of gas
mantles. It is a moderately to strongly
radioactive mineral, (Ce,La,Y,Th)POtt. It
occurs widely disseminated as an accessory
mineral in granitic igneous rocks and gneissic
metamorphic rocks. Detrital sands in regions
of such rocks may contain commercial
quantities of monazite. Thorium-free monazite
is rare.
860
-------
New source Performance Standard - Performance standards for
the industry and applicable new sources as
defined by Section 306 of the Act.
niccolite - A copper-red arsenide of nickel which usually
contains a little iron, cobalt, and sulfur.
It is one of the chief ores of metallic
ni?*.er nickel minerals - The nickel-iron
sulfide, pentlandite ((Fe, Ni)Ss Q is the
principal present economic source"" of nickel,
and garnierite (nickelmagnesium hydrosilicate)
is next in economic importance,
oleic acid - A mono-saturated fatty acid,
CH3(CH2)_LCH:CH(CH2)7 COOH. A common component
of almost all naturally occurring fats as well
as tall oil. Most commercial oleic acid is
derived from animal tallow or natural
vegetable oils.
open-pit mining, open cut mining - A form of operation
designed to extract minerals that lie near the
surface. Waste, or overburden, is first
removed, and the mineral is broken and loaded.
Important chiefly in the mining of ores of
iron and copper.
ore - (a) A natural mineral compound of the elements of
which one at least is a metal. Applied more
loosely to all metalliferous rock, though it
contains the mefcal in a free state, and
occasionally to the compounds of nonmetallic
substances, such as sulfur, (b) A mineral of
sufficient value as to quality and quantity
which may be mined with profit.
ore dressing - The cleaning of ore by the removal of certain
valueless portion as by jigging, cobbing,
vanning and the like. Synonym for concentra-
tion. The same as mineral dressing.
The term is usually restricted to ore of which
the grade and tonnage have been established
with reasonable assurance by drilling and
other means.
oxidized ores - The alteration of metalliferous minerals by
weathering and the action of surface waters,
ore reserve -
661
-------
and the conversion of the minerals
oxides, carbonates, or sulfates.
into
oxidized
zone - That portion of an ore body near the
surface, which has been leached by percolating
water carrying oxygen, carbon dioxide or other
gases.
pegmatite - An igneous rock of coarse grain size usually
found as a crosscutting structure in a larger
igneous mass of finer grain size.
pelletizing - A method in which finely divided material is
rolled in a drum or on an inclined disk, so
that the particles cling together and roll up
into small, spherical pellets.
pH modifiers - Proper functioning of a cationic or anionic
flotation reagent is dependent on the close
control of pH. Modifying agents used are soda
ash, sodium hydroxide, sodium silicate, sodium
phosphates, lime, sulfuric acid, and
hydrofluoric acid.
placer mine - (a) A deposit of sand, gravel, or talus from
which some valuable mineral is extracted. (b)
To mine gold, platinum, tin or other valuable
minerals by washing the sand, gravel, etc.
placer mining * The extraction of heavy mineral from a
placer deposit by concentration in running
water. It includes ground sluicing, panning,
shoveling gravel into a sluice, scraping by
power scraper, excavation by dragline or
extraction by means of various types of
dredging activities.
platinum minerals - Platinum, ruthenium, rhodium, palladium,
osmium, and iridium are members of a group
characterized by high specific gravity,
unusual resistance to oxidizing and acidic
attack, and high melting point.
point source - Any discernible, confined and discrete
conveyance, including but not limited to any
pipe, ditch, channel, tunnel, conduit, well,
discrete fissure, container, rolling stock,
concentrated animal feeding operation, or
862
-------
vessel or other floating craft, from which
pollutants are or may be discharged.
pregnant solution - A value bearing solution in a
hydrometallurgical operation.
pregnant solvent - In solvent extraction, the value-bearing
solvent produced in the solvent extraction
circuit.
promoter - A reagent used in froth-flotation process,
usually called the collector.
rare-earth deposits - Sources of cerium, terbium, yttrium,
and related elements of the rare-earth's
group, as well as thorium.
raw mine drainage - Untreated or unprocessed water drained,
pumped or siphoned from a mine.
reagent - A chemical or solution used to produce a desired
chemical reaction; a substance used in assay-
ing or in flotation.
reclamation - The procedures by which a disturbed area can
be reworked to make it productive, useful, or
aethetically pleasing.
recovery - A general term to designate the valuable
constituents of an ore which are obtained by
metallurgical treatment.
reduction plant - A mill or a treatment place for the
extraction of values from ore.
roast - To heat to a point somewhat short of fuzing in order
to expel volatile matter or effect oxidation.
rougher cell - Flotation cells in which the bulk of the
gangue is removed from the ore.
roughing - upgrading of run-of-mill feed either to produce a
low grade preliminary concentrate or to reject
valueless tailings at an early stage.
Performed by gravity on roughing tables, or in
flotation in a rougher circuit.
rutile - Titanium dioxide, TiO£.
863
-------
scintillation counter - An instrument used for the location
of radioactive ore such as uranium. It uses a
transparent crystal which gives off a flash of
light when struck by a gamma ray, and a
photomultiplier tube which produces an
electrical impulse when the light from the
crystal strikes it.
selective flotation - See differential flotation.
settling pond - A pond, natural or artificial, for
recovering solids from an effluent.
siderite - An iron carbonate, FeCO^J.
slime, slimes - A material of extremely fine particle size
encountered in ore treatment.
sludge - The precipitant or settled material from a waste
water.
slurry - (a) Any finely divided solid which has settled out
as from thickeners. (b) A thin watery
suspension.
solvent extraction - See liquid-liquid extraction.
sphalerite - Zinc sulfide, ZnS. stibnite - An antimony
sulfide, Sb2S3. The most important ore of
antimony. ~~ ~"
suction dredge - (a) Essentially a centrifugal pump mounted
on a barge. (b) A dredge in which the
material is lifted by pumping through a
suction pipe.
sulfide zone - That part of a lode or vein not yet oxidized
by the air or surface water and containing
sulfide minerals.
surface active agent - One which modifies physical,
electrical, or chemical characteristics of the
surface of solids and also surface tensions of
solids or liquid. Used in froth flotation
(see also depressing agent, flotation agent).
tabling - Separation of two materials of different densities
by passing a dilute suspension over a slightly
inclined table having a reciprocal horizontal
864
-------
motion or shake with a slow forward motion and
a fast return*
taconite - (a) The cherty or jaspery rock that encloses the
Mesabi iron ores in Minnesota. In a somewhat
more general sense, it designates any bedded
ferruginous chert of the Lake Superior
District. (b) in Minnesota practice, is any
grade of extremely hard, lean iron ore that
has its iron either in banded or well-
disseminated form and which may be hematite or
magnetite, or a combination of the two within
the same ore body (Bureau of Mines).
taconite ore - A type of highly abrasive iron ore now exten-
sively mined in the United states.
tailing pond - Area closed at lower end by constraining wall
or dam to which mill effluents are run.
tailings - (a) The parts, or a part, of any incoherent or
fluid material separated as refuse, or
separately treated as inferior in quality or
value; leavings; remainders; dregs. (b) The
gangue and other refuse material resulting
from the washing, concentration, or treatment
of ground ore. (c) Those portions of washed
ore that are regarded as too poor to be
treated further; used especially of the debris
from stamp mills or other ore dressing machin-
ery, as distinguished from concentrates.
tall oil - The oily mixture of rosin acids, and other
materials obtained by acid treatment of the
alkaline liquors from the digesting (pulping)
of pine wood. Used in drying oils, in cutting
oils, emulsifiers, and in flotation agents.
tantalite - A tantalate of iron and manganese (Fe,Mn)Ta2O ,
crystallizing in the ortborhombic system.
tetrahedrite - A mineral, the part with sb greater than As
of the tetrahedrite-tenantite series,
Cu3(Sb,As)S3. Silver, zinc, iron and mercury
may replace part of the copper. An important
ore of copper and silver.
865
-------
thickener - A vessel or apparatus for reducing the amount of
water in a pulp.
thickening - (a) The process of concentrating a relatively
dilute slime pulp into a thick pulp, that is,
one containing a smaller percentage of mois-
ture, by rejecting liquid that is essentially
solid free. (b) The concentration of the
solids in a suspension with a view to recover-
ing one fraction with a higher concentration
of solids than in the original suspension.
tin minerals - Virtually all the industrial supply comes
from cassiterite(SnO2)• though some has been
obtained from the sulfide minerals stannite,
cylindrite, and frankeite. The bulk of cas-
siterite comes from alluvial workings.
titanium minerals - The main commercial minerals are
(Ti02) and ilmenite (FeTiO3).
rutile
tyuyamunite - A yellow uranium mineral, Ca (OO2) 2 (VO**) 2 .
3H2O. It is the calcium analogue of
carnotite.
uraninite - Essentially U02. It is a complex uranium
mineral containing also rare earths, radium,
lead, helium, nitrogen and other elements.
uranium minerals - More than 150 uranium bearing minerals
are known to exist, but only a few are common.
The five primary uranium-ore minerals are
pitchblende, uraninite, davidate, coffinite,
and brannerite. These were formed by deep-
seated hot solutions and are most commonly
found in veins or pegmatites. The secondary
uranium-ore minerals, altered from the primary
minerals by weathering or other natural pro-
cesses, are carnotite, tyuyamunite and meta-
tyuyamunite (both very similar to carnotite),
torbernite and metatorbernite, autunite and
meta-autunite, and uranophane.
vanadium minerals - Those most exploited for industrial use
are patronite (VS£), roscoelite (vanadium
mica), vanadinite (Pb_cl (VO4)3), carnotite and
chlorovanadinite. ~"
866
-------
vat leach - Employs the dissolution of copper oxide minerals
by suIfuric acid from crushed, non-porous ore
material placed in confined tanks. The leach
cycle is rapid and measured in days.
weir - An obstruction placed across a stream for the purpose
of diverting the water so as to make it flow
through a desired channel, which may be an
opening or notch in the weir itself.
wetting agent - A substance that lowers the surface tension
of water and thus enables it to mix more
readily. Also called surface active agent.
Wilfley table - A widely used form of shaking table. A
plane rectangle is mounted horizontally and
can be sloped about its long axis. It is
covered with linoleum (occasionally rubber)
and has longitudinal riffles dying at the
discharge end to a smooth cleaning area,
triangular in the upper corner. Gentle and
rapid throwing motion is used on the table
longitudinally. Sands, usually classified for
size range are fed continuously and worked
along the table with the aid of feedwater, and
across riffles downslope by gravity tilt
adjustment, and added washwater. At the
discharge end, the sands have separated into
bands, the heaviest and smallest uppermost,
the lightest and largest lowest.
xanthate - Common specific promoter used in flotation of
sulfide ores. A salt or ester of xanthic acid
which is made of an alcohol, carbon disulfide
and an alkalai. xenotime - A yttrium
phosphate, YPO
-------
obtained by evaporating an ammonia solution of
the oxide.
zinc minerals - The main source of zinc is sphalerite (ZnS),
but some smithsonite, hemimorphite, zincite,
willemite, and franklinite are mined.
zircon - A mineral, ZrSiOU.. The chief ore of zirconium.
zircon, rutile, ilmenite, monazite - A group of heavy min-
erals which are usually considered together
because of their occurrence as black sand in
natural beach and dune concentration. to
discharge may be necessary. prior to
discharge may be necessary, presented in this
section will be consolidated, where possible,
in -the regulations derived from this
development document.
868
-------
SECTION XV
BIBLIOGRAPHY
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869
-------
13. Anon, "Anaconda's Pesin-in-Pulp Process: Another
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870
-------
26, Anon, "Kerr-McGee's Ambrosia Complex: From Mined
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871
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40. Anon, "Solving the Problem of Acid Mine Drainage,"
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913
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