EPA
GROUP II,
Development Document for
Interim Final Effluent Limitations Guidelines
and New Source Performance Standards
for the
MINERALS FOR THE
CONSTRUCTION INDUSTRY
VOL. I
MINERAL MINING AND
PROCESSING INDUSTRY
Point Source Category
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
OCTOBER 1975
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DEVELOPMENT DOCUMENT
for
INTERIM FINAL
EFFLUENT LIMITATIONS GUIDELINES
and STANDARDS Of PERFORMANCE
MINERAL MINING AND PROCESSING INDUSTRY
VOLUME I
Minerals for the Construction Industry
Russell E. Train
Administrator
Andrew W. Breidenbach, Ph.D.
Acting Assistant Administrator for
Water and Hazardous Materials
Eckardt c. Beck
Deputy Assistant Administrator for
Water Planning and Standards
Allen Cywin
Director, Effluent Guidelines Division
Michael w. Kosakowski
Project Officer
October 1975
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
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CONTENTS
section
Abstract i
I Conclusions 1
II Recommendations 3
III Introduction 5
IV Industry Categorization 51
V Water Use and Waste Characterization 55
VI Selection of Pollutant Parameters 151
VII Control and Treatment Technology 161
VIII Cost Energy and Non-Water Quality Aspects 193
IX Effluent Reduction Attainable Through 239
the Application of the Best Prac-
ticable Control Technology Currently
Available
X Effluent Reduction Attainable Through 255
Application of the Best Available
Technology Economically Achievable
XI New Source Performance Standards and 261
Pretreatment standards
XII Acknowledgements 267
XIII References 269
XIV Glossary 273
iii
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FIGURES
Page
1 Dimensional Granite 14
2 Dimensional Limestone 15
3 Dimensional, Sandstone, Quartz, Quartzite 16
4 Crushed Granite 21
5 Crushed Limestone and Dolomite 22
6 Sand and Gravel Production 27
7 Sand and Gravel Facilities 28
8 Industrial Sand Deposits 33
9 Gypsum Operations 39
10 Asbestos Deposits 44
11 Dimension Stone Mining and Processing 61
12 Crushed Stone (Dry) Mining and 70
Processing
13 Crushed Stone (Wet) Mining and 72
Processing
14 Crushed Stone (Flotation) Mining 79
and Processing
15 Sand and Gravel (Dry) Mining and 83
Processing
16 Sand and Gravel (Wet) Mining and 87
Processing
17 Sand and Gravel (HMS) Mining and 88
Processing
18 Sand and Gravel (Dredging with On- 94
land Processing) Mining and
Processing
19 Industrial Sand (Dry) Mining and 101
Processing
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20 Industrial Sand (Wet) Mining and 104
Processing
21 Industrial Sand (Flotation) Mining 10?
and Processing
22 Gypsum (Dry) Mining and Processing 112
23 Gypsum (HMS) Mining and Processing 117
24 Bituminous Limestone Mining and 120
Processing
25 Oil Impregnated Diatomite Mining 121
and Processing
26 Gilsonite Mining and Processing 123
27 Asbestos (Dry) Mining and Processing 126
28 Asbestos (Wet) Mining and Processing 129
29 Wollastonite Mining and Processing 132
30 Perlite Mining and Processing 134
31 Pumice Mining and Processing 137
32 Vermiculite Mining and Processing 139
33 Mica and Sericite (Dry) Mining and 143
Processing
34 Mica (Wet) Mining and Processing 145
35 Mica (Flotation or Spiral Separation) 143
Mining and Processing
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TABLES
Table
1 Recommended BPCTCA and BATEA for the 4
Minerals for the Construction
Industry Segment of the Mineral
Mining and Processing Industry, for
Process Water Only
2 Data Base 9
3 1972 Production and Employment Figures 12
for the Industries Mining and Pro-
cessing Minerals for the Construction
Industry
4 Dimension Stone Shipped or Used by 17
Producers in the United States, by
Use and Kind of Stone
5 1973 Size Distribution of Crushed Stone 20
Facilities
6 1972 Uses of Crushed Stone 25
7 1972 Size Distribution of Sand and 29
Gravel Facilities
8 1972 Uses of Sand and Gravel 31
9 1972 Uses of Industrial Sand 34
10 Industry Categorization 53
11 Dimension Stone Water Use 64
12 Settling Pond Performance stone, 182
Sand and Gravel operations
13 Summary of Technology Applications, 189
Limitations and Reliability
14 Capital Investments and Energy Con- 195
sumption of Present Waste water
Treatment Plants
15 Cost for a Representative Plant 201
(Dimension Stone)
16 Cost for a Representative Plant 204
vii
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(Crushed Stone, Wet Process)
17 Cost for a Representative Plant 209
(Construction Sand and Gravel, Wet
Process)
18 cost for a Representative Plant 216
(Industrial Sand, Wet Process)
19 Cost for a Representative Plant 219
(Industrial Sand, Acid and Alkaline
Process)
20 Cost for a Representative Plant 221
(Industrial Sand, HF Flotation)
21 Cost for a Representative Plant 226
(Gilsonite)
22 Cost for a Representative Plant 230
(Vermiculite)
23 Cost for a Representative Plant 233
(Mica, eastern)
24 Conversion Table - — • 280
viii
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SECTION I
CONCLUSIONS
For purposes of establishing effluent limitations guidelines
and standards of performance, and for ease of presentation,
the mineral mining industry has been divided into three
segments to be published in three volumes: minerals for the
construction industry; minerals for the chemical and
fertilizer industries; and clay, ceramic, refractory and
miscellaneous minerals. These divisions reflect the end
uses of the minerals after mining and beneficiation. In
this volume covering minerals for the construction industry,
the 15 minerals were grouped into 9 production subcategories
for reasons explained in Section IV.
Based on the application of best practicable technology
currently available, 6 of the 9 production subcategories
under study can be operated with no discharge of process
generated waste water pollutants to navigable waters. With
the best available technology economically achievable, 8 of
the 9 production subcategories can be operated with no
discharge of process generated waste water pollutants to
navigable waters. No discharge of process generated waste
water pollutants to navigable waters is achievable as a new
source performance standard for all production subcategories
except mica (wet beneficiation process with ceramic grade
clay as by-product). Mine water and contaiminated facility
runoff discharge are considered separately for each
subcategory.
This study included 15 minerals for the construction
industry of Standard Industrial Classification (SIC)
categories 1411, 1422, 1423, 1429, 1442, 1446, 1492, and
1499 with significant waste discharge potential as given in
the following list with the corresponding SIC code.
1. Dimension Stone (1411)
2. Crushed Stone (1422, 1423, 1429)
3. Construction Sand and Gravel (1442)
4. Industrial Sand (1446)
5. Gypsum (1492)
6. Asphaltic Minerals (1499)
a. Bituminous Limestone
b. Oil Impregnated Diatomite
c. Gilsonite
7. Asbestos and Wollastonite (1499)
8. Lightweight Aggregate Minerals (1499)
a. Perlite
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b. Pumice
c. Vermiculite
9. Mica and Sericite (1499)
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SECTION II
RECOMMENDATIONS
The recommended effluent limitations guidelines and the
suggested technologies are listed in Table 1. pH should be
maintained between 6.0 and 9.0 units at all times.
The pretreatment standards will not limit total suspended
solids or pH, unless ther6 is a problem of sewer plugging,
in which case 40 CFR 182.131(c) applies. Limitations for
parameters other than TSS and pH are recommended to be the
same as proposed for best practicable control technology
currently available (for existing sources) and for new
source performance standards (for new sources).
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Table 1
RecoTf-msnded Limits and Standards for the Mineral Mining and Processing Industry
The following apply to process waste water except where noted.
Subcategory BPCTCA 3ATEA and NSPS
max. avg. of 30 TT-IX. for nax. avg. of 30 max. for
consecutive days any one day consecutive days any one day
Dimension stone,
Crushed stons, &
Construction Sand and
Gravel No discharge No discharge
Mine drainage . TSS 30 rag/1 TSS 30 mg/1
Industrial Sand
Dry processing,
Wet processing, &
Non HF flotation No discharge ' No discharge
HF flotation TSS 0,044 kg/kkg TSS 0.038 kg/kkg No discharge
F 0.005 kg/kkg F 0.01 kg/kkg
Mine drainage TSS 30 rag/1 TSS 30 mg/1
Gypsum
Dry s-
Heavy i'edia Separation No discharge No discharge
Wet Scrubbers TSS 0.13 kg/kkg TSS 0,26 kg/kkg No discharge
Mine drainage TSS 30 mg/1 TSS 30 rag/1
Bituminous limestone,
Oil-y.rapregnated diatomite,
Oilsonite,
Asbestos, Wollostonite,
Perlite,
Puird.ce,
Vennicul-i'rt:, and expanded
lightweight aggregates No discharge No discharge
Mine drainage TSS 30 mg/1 XSS 30 mg/1
Mica & Sericite
Dry pror.sslng,
Wet processing &
Wet processing and
general clay recovery Ho discharge No discharge
Wet processing and
Ceramic grade clay
recovery TSS 1.5 kg/kkg TSS 3.0 kg/kkg TSS 1.25 kg/kkg XSS 2.3 kg/kkg
Mine drainage TSS 30 irg/1 TSS 30 mg/1
pH 6-9 for all subcategories
No discharge - Mo discharge of process waste water pollutants
kg/kkg - kg of pollutant/kkg of product
BPCTCA - Best practicable control technology
,-'AT£A - Best available Lcchnolcgy economically achievable
-iSi-S - Kew source parfor. -ir.c.e standari
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SECTION III
INTRODUCTION
PURPOSE AND AUTHORITY
The United States Environmental Protection Agency (EPA) is
charged under the Federal Water Pollution Control Act
Amendments of 1972 with establishing effluent limitations
which must be achieved by point sources of discharge into
the navigable water of the United States.
Section 301 (b) of the Act requires the achievement by not
later than July 1, 1977, of effluent limitations for point
sources, other than publicly owned treatment works, which
are based on the application of the best practicable control
technology currently available as defined by the
Administrator pursuant to Section 304(b) of the Act.
Section 301(b) also requires the achievement by not later
than July 1, 1983, of effluent limitations for point
sources, other than publicly owned treatment works, which
are based on the application of the best available
technology economically achievable which will result in
reasonable further progress toward the national goal of
eliminating the discharge of all pollutants, as determined
in accordance with regulations issued by the Administrator
pursuant to Section 304(b) to the Act. Section 306 of the
Act requires the achievement by new sources of a Federal
standard of performance providing for the control of the
discharge of pollutants which reflects the greatest degree
of effluent reduction which the Administrator determines to
be achievable through the application of the best available
demonstrated control technology, processes, operating
methods r or other alternatives, including, where
practicable, a standard permitting no discharge of
pollutants. Section 304(b) of the Act requires the
Administrator to publish within one year of enactment of the
Act, regulations providing guidelines for effluent
limitations setting forth the degree of effluent reduction
attainable through the application of the best practicable
control technology currently available and the degree of
effluent reduction attainable through the application of the
best control measures and practices achievable including
treatment techniques, process and procedure innovations,
operating methods and other alternatives. The regulations
proposed herein set forth effluent limitations guidelines
pursuant to Section 304 (b) of the Act for the minerals for
the Construction Industry segment of minerals for the
construction industry segment of the mineral mining and
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processing industry point source category. Section 306 of
the Act requires the Administrator, within one year after a
category of sources is included in a list published pursuant
to Section 306(b) (1) (A) of the Act, to propose regulations
establishing Federal standards of performances for new
sources within such categories. The Administration
published in the Federal Register of January 16, 1973 (38
F.R. 1624), a list of 27 source categories. Publication of
an amended list will constitute announcement of the
Administrator's intention of establishing, under Section
306, standards of performance applicable to new sources
within the mineral mining and processing industry. The list
will be amended when proposed regulations for the Mineral
Mining and Processing Industry are published in the Federal
Register.
SUMMARY OF METHODS
The effluent limitations guidelines and standards of per-
formance proposed herein were developed in a series of
systematic tasks. The mineral mining and processing
industry was first studied to determine whether separate
limitations and standards are appropriate for different
segments within a point source category. Development of
reasonable industry categories and subcategories, and
establishment of effluent guidelines and treatment standards
requires a sound understanding and knowledge of the mineral
mining and processing industry, the processes involved,
waste water generation and characteristics, and capabilities
of existing control and treatment methods.
This report describes the results obtained from application
of the above approach to the minerals for the construction
industry segment of the mineral mining and processing
industry. Thus, the survey and testing covered a wide range
of processes, products, and types of wastes.
The products, covered in this report are listed below with
their SIC designations:
a. Dimension stone (1411)
b. Crushed stone (1422, 1423, 1429, 1499)
c. Construction sand and gravel (1442)
d. Industrial sand (1446)
e. Gypsum (1492)
f. Asphaltic Minerals (1499)
g. Asbestos and Wollastonite (1499)
h. Lightweight Aggregates (1499)
i. Mica and Sericite (1499)
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Some of the above minerals which are processed only (3295)
are also included.
Categorization and Waste Load Characterization
The effluent limitation guidelines and standards of per-
formance proposed herein were developed in the following
manner. The point source category was first categorized for
the purpose of determining whether separate limitations and
standards are appropriate for different segments within a
point source category. Such subcategorization was based
upon raw material used, product produced, manufacturing
process employed, and other factors. The raw wastes
characteristics for each subcategory were then identified.
This included an analysis of (1) the source and volume of
water used in the process employed and the sources of waste
and waste waters at the facility; and (2) the constituents
of all waste waters including harmful pollutants and other
constituents which could result in degradation of the
receiving water. The pollutants of waste waters which
should be subject to effluent limitations guidelines and
standards of performance were identified.
Treatment and Control Technologies
The full range of control and treatment technologies
existing within each subcategory was identified. This
included an identification of each control and treatment
technology, including both in-facility and end-of-process
technologies, which are existent or capable of being
designed for each subcategory. It also included an
identification of the amount of pollutants (including
thermal) and the characteristics of pollutants resulting
from the application of each of the treatment control
technologies. The problems, limitations, and reliability of
each treatment and control technology were also identified.
In addition, the non-water quality environmental impact,
such as the effects of the application of such technologies
upon other pollution problems, including air, solid waste,
noise and radiation were also identified. The energy
requirements of each of the control and treatment
technologies were identified as well as the cost of the
application of such technologies.
Data Base
The data for identification and analyses were derived from a
number of sources. These sources included EPA research
information, published literature, qualified technical
consultation, on-site visits and interviews at numerous
mining and processing facilities throughout the U.S.,
interviews and meetings with various trade associations, and
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interviews and meetings with various regional offices of the
EPA. All references used in developing the guidelines for
effluent limitations and standards of performance for new
sources reported herein are included in Section XIII of this
report. Table 2 summarizes the data base for the various
subcategories in this volume.
Facility Selection
The following selection criteria were developed and used for
the selection of facilities.
Discharge effluent quantities
Facilities with lowest effluent quantities or the ultimate
of no discharge of process generated waste water pollutants
were selected. These facilities might have reuse of water,
raw material recovery and recycling, or use of evaporation.
The significant criterion was minimal waste added to
effluent streams per weight of product manufactured.
Land utilization
The efficiency of land use was considered.
Air pollution and solid waste control
The facilities must have possessed overall effective air and
solid waste pollution control where relevant in addition to
water pollution control technology. Care was taken to
insure that all facilities chosen have minimal discharges
into the environment and that these sites do not exchange
one form of pollution for another of the same or greater
magnitude.
Effluent treatment methods and their effectiveness
Facilities selected shall have in use the best currently
available treatment methods, operating controls, and
operational reliability. Treatment methods considered
included basic process modifications which significantly
reduce effluent loads as well as conventional treatment
methods.
Facility facilities
All facilities chosen had all the facilities normally
associated with the production of the specific product (s) in
question. Typical facilities generally were facilities
which have all their normal process steps carried out
on-site.
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TABLE 2
DATA BASE
Subcategory
No._
Plants
194
,800
,700
10
50
750
,250
50
100
20
130
17
Dimension Stone
Crushed Stone
Dry 1
Wet 2
Flotation
Shell Dredging
Construction Sand
Gravel
Dry
Wet 4
Dredging (on-land)
Dredging (on-board)
Industrial Sand
Dry
Wet
Flotation (Acid &
Alkaline)
Flotation (HF) 1
Gypsum
Dry 73
Wet Scrubbing 5
HMS 2
Asphaltic Minerals
Bituminous Limestone 2
Oil Impreg.Diatomite 1
Gilsonite 1
Asbestos
Dry 4
Wet . 1
Wollastonite 1
Lightweight Aggregates
Perlite 13
Pumice 7
Vermiculite 2
Mica & Sericite
Dry ' 7
Wet 3
Wet Beneficiation 7
TOTAL 10,201
No Plants
Visited
20
5
26
2
4
0
46
8
3
0
3
4
1
5
1
1
0
1
1
2
1
1
4
2
2
5
2
5
155
Data
Available
20
52
130
3
4
50
100
15
25
5
10
10
1
54
8
2
2
1
1
4
1
1
4
7
2
7
3
7
529
Sampled
5
*
9
1
0
*
15
0
0
*
2
2
1
2
1
A
A
A
1
1
A
*
A
A
A
A
A
40
* There is no discharge of process waste water in this subcategory
under normal operating conditions.
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Facility management, philosophy
Facilities were preferred whose management insists upon
effective equipment maintenance and good housekeeping
practices. These qualities are best identified by a high
operational factor and facility cleanliness.
Geographic location
Factors which were considered include facilities operating
in close proximity to sensitive vegetation or in densely
populated areas, other factors such as land availability,
rainfall, and differences in state and local standards were
also considered-
Raw materials
Differences in raw materials purities were given strong con-«
sideration in cases where the amounts of wastes are strongly
influenced by the purity of raw materials used. Several
facilities using different grades of raw materials were
considered for those minerals for which raw material purity
is a determining factor in waste control.
Diversity of processes
On the basis that all of the above criteria are met,
consideration was given to installations having a
multiplicity of manufacturing processes. However, for
sampling purposes, the complex facilities chosen were those
for which the wastes could be clearly traced through the
various treatment steps.
Production
On the basis that other criteria are equal, consideration
was given to the degree of production rate scheduled on
water pollution sensitive equipment.
Product
For cases in which purity requirements play a major role in
determining the amounts of wastes to be treated and the
degree of water recycling possible, different product grades
were considered for subcategorization.
GENERAL DESCRIPTION OF INDUSTRY BY PRODUCT
The materials categorized in SIC groups 141, 142, 144,
industry code 1492, and select minerals in code 1499, have
much in common in terms of their occurrence, mining and
processing methods, and end product use.
10
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General processing for crushed and broken stone includes
quarrying or mining, crushing of oversize, and sizing of the
crushed material. Use of crushed stone by the construction
industry accounts for over 50 percent of crushed stone
consumption. Other uses include manufactured fine aggregate
and lime manufacture. The degree of material processing is
dependent on customer demand. Dimension stone is quarried
or mined in block form and requires special saws and
equipment for dressing the finished stone. Monumental
granite is the largest use category, in terms of value.
Sand and gravel is quarried or hydraulically mined, the
oversize is crushed, sand and gravel separated by water,
gravel sized and sand hydraulically classified. Over 90
percent of sand and gravel consumption is by the
construction industry. Industrial sand is quarried or
mined, the oversize is crushed, impurities are washed out,
milled, graded according to size, and dried. Glass sand is
generally beneficiated by flotation to yield a low iron
content product. Predominant uses for industrial sand
include glassmaking, molding, and foundry sand, all
important to the construction industry. Gypsum is quarried
or mined, the oversize is crushed, and milled into "land
plaster." Most "land plaster" is calcined and processed into
gypsum board products for use by the construction industry.
Asphaltic minerals are usually extracted from an open pit,
crushed, sized, and sold as a substitute for synthetic
asphalt products. Asbestos is quarried or mined, the
oversize is crushed, dried, and air classified into specific
fiber lengths. Asbestos is used as an insulator and
fireproofing material in the construction industry.
Lightweight aggregates are either quarried or expanded into
lightweight construction materials. Mica is mined,
beneficiated, and ground into insulation or filler material
used in the construction and electrical industries.
The 1972 production and employment figures for the
industries mining and processing minerals for the
construction industry were derived either from the Bureau of
the Census (U.S. Department of Commerce) publications or the
Commodity Data Summaries (1974) Appendix I to Mining and
Minerals Policy, Bureau of Mines, U.S. Department of the
Interior. These figures are tabulated in Table 3.
DIMENSION STONE (SIC 1411)
Rock which has been specially cut or shaped for use in
buildings, monuments, memorial and gravestones, curbing, or
other construction or special uses is called dimension
stone. Large quarry blocks suitable for cutting to specific
dimensions are also classified as dimension stone. The
principal dimension stones are granite, marble, limestone.
11
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TABLE 3
1972 Production and Employment Figures
for the Industries Mining and Processing
Minerals for the Construction Industry
SIC 1972 Production
Code Product 1000 kkg 1000 tons Employment
1411 Dimension stone- 542 598 2,000
limestone combined
1411 Dimension stone- 357 394 SIC 1411
granite
1411 Dimension stone- 559 616
other*
1422 Crushed & broken 542,400 598,000 29,400
stone-limestone
1423 Crushed & broken 95,900 106,000 4,500
stone granite
1429 Crushed & broken 113,000 124,600 7,400
stone NEC
1499 Crushed & broken 19,.000 (20,900) Unknown
stone shell
1442 Construction sand 650,000 717,000 30,300
& gravel
1446 Industrial sand 27,120 29,999 4,400
1492 Gypsum 11,200 12,330 2,900
1499 Bituminous Limestone 1,770 1,950 Unknown
1499 Oil-impregnated 109 120 Unknown
diatomite
1499 Gilsonite 45 50 Unknown
1499 Asbestos 120 132 400
1499 Wollastonite 63 70 70
1499 Perlite 589 649 100
1499 Pumice 3,460 3,810 525
1499 Vermiculite 306 337 225
1499 Mica 145 160 75
* Sandstone, marble, et al
12
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slate, and sandstone. Less common are diorite, basalt, mica
schist, quartzite, diabase and others.
Terminology in the dimension stone industries is somewhat
ambiguous and frequently does not correspond to the same
terms used in mineralogical rock descriptions. Dimension
granites include not only true granite, but many other types
of igneous and metamorphic rocks such as quartz diorites,
syenites, quartz porphyries, gabbros, schists, and gneisses.
Dimension marble may be used as a term to describe not only
true marbles, which are metamorphosed limestones, but also
any limestone that will take a high polish. Many other
rocks such as serpentines, onyx, travertines, and some
granites are frequently called marble by the dimension stone
industry. Hard cemented sandstones are sometimes called
quartzite although they do not specifically meet the
mineralogical definition.
Many of the continental United States possess dimension
stone of- one kind or other, and many have one or more
producing operations. However, only a few have significant
operations. These are as follows:
Granite - Minnesota
Georgia
Vermont
Massachusetts
South Dakota
Marble - Georgia
- Vermont
Minnesota (dolomite)
Limestone - Indiana
Wisconsin
Slate - Vermont
New York
Virginia
Pennsylvania
Sandstone, Quartz, and Quartzite - Ohio, Pennsylvania,
and New York
Figures 1, 2 and 3 give the U. S. production on a state
basis for granite, limestone and sandstone, quartz and
quartzite respectively the principal stones quarried as
shown in Table 4. There are less than 500 dimension stone
mining activities in the U.S. Present production methods
for dimension stone range from the inefficient antiquated to
the technologically modern* Quarrying methods include use
of various combinations of wire saws, jet torches,
channeling machines, drilling machines, wedges, and
13
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FIGURE 1.
DIMENSIONAL GRANITE
1972/1000 short tons
* Producing States (total = 214.0)
National Total = 621.2
Data From: Minerals Yearbook - 1972, Vol. I
Table 5, p. 1164
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FIGURE 2
DIMENSIONAL LIMESTONE
1972/1000 short tons
* Producing States (Total = 54.8)
National Total = 411.1 (excluding P.R.)
Data From: Minerals Yearbook - 1972, Vol. I
Table 6, p. 1164
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FIGURE 3
DIMENSIONAL SANDSTONE,
QUARTZ, QUARTZITE
1972/1000 short tons
* Producing States (Total = 22.3}
National Total - 230.7
Data From: Minerals Yearbook - 1972, Vol I
Table 7, p. 1165
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Table 4
DIMENSION STONE SHIPPED Oil VKKTi By rKOlXJCEHS IK THE
UNITEi> STATES, BY USK AN'. K.T.NI) OF -.TON!-
Kind of stone and use
GRANITE
1000 short tons
Kind of slonc mid use
continued
Dressed:
1000 short tons
Rough :
Arch1"ecturnl
Cons L - uct ion
i.onumental
Other rough stone
Dressed ;
Cut
Sawed
House stone veneer
Construction
Monumental
Curbing
Flagging
Paving blocks
Other dressed stone
Total
Value ($1000)
LIMESTOIIE AND DOLOMITE
Rough:
Architectural
Construction
Flagging
Other rough stone
Dressed:
Cut
Sawed
House stone veneer
Construction
Flagging
Other dressed stone
Total
Value ($1000)
KASBLE
Rough: Architectural
Dressed :
Cut
. Sawed
House stone veneer
Construction and Monumental
Total
Value ($1000)
SANDSTONE, QUARK 6 QUAHTZITS
Rough:
Architectural
Construct Ion
Flaeglng
Other rough stone
• 46
54
287
—
14
6
10
33
130
—
—
42
621
42,641
175
56
18
1
49
30
68
12
2
1
411
14,378
9
21
5
9
27
71
16,541
42
74
18
1
Cut
Curbing
Snwcd
House stone veneer
Flagging
Other uses not listed
Total
Value ($1000)
SLATE
Roofing slate
Millstock:
Structural and sanitary
Blackboards, etc.
Billiard table tops
Total
Flagging
Other uses not listed
Total
Value ($1000)
OTHER STONE
Rough:
Architectural
Construction
Dressed:
Cut
Construction
Flagging
Structural and sanitary purposes
Total
Value ($1000)
TOTAL STOHE
Rough:
Architectural
Construction
Monumental
Flagging
Other rough stone
Dressed:
Cut
Sawed
House stone veneer
Cony t ruction
Footing (elate)
milstock (slate)
MomiBientnl
Curbing
Flagging
Othtr uses not listed
Total
Value (S1000)
21
~ '
—
27
17
32
231
7,684
12
U
I
4
19
36
14
80
7,404
14
43
2
4
—
66
1,964
286
239
287
36
2
117
65
110
32
12
19
65
130
61
31
1,490
90,763
Minerals Yearbook, 1972, U.S. Department of the Interior,
Bureau of Min<-K
17
-------
broaching tools. The choice of equipment mix depends on the
type of dimension stone, size and shape of deposit,
production capacity, labor costs, financial factors, and
management attitudes.
Blasting with a low level explosive such as black powder, is
occasionally used. Blocks cut from the face are sawed or
split into smaller blocks for ease in transportation and
handling. The blocks are taken to processing facilities,
often located at the quarry site, for final cutting and
finishing operations. Stone finishing equipment includes:
(a)gang saws (similar to large hack saws), used with water
alone, or water with silicon carbide (SiC) abrasive added,
and recently, with industrial diamond cutting edges; (b)wire
saws used with water alone, or with water and quartz sand,
or water with SiC; (c)diamond saws; (d)profile grinders;
(e)guillotine cutters; (f)pneumatic actuated cutting tools
(chisels); (g)sand blasting, shot peening; and (h)polishing
mills.
CRUSHED STONE (SIC 1422, 1423 and 1429)
This stone category pertains to rock which has been reduced
in size after mining to meet various consumer requirements.
As with dimension stone, the terminology used by the crushed
stone producing and consuming industries is not consistent
with mineralogical definitions. Usually all of the coarser
grained igneous rocks are called granite. The term traprock
pertains to all dense, dark, and fine-grained igneous rocks.
Quartzite may describe any siliceous-cemented sandstone
whether or not it meets the strict mineralogical
description. As the table that follows shows approximately
three-fourths of all crushed stone is limestone or
lime stone-dolomite ,
PRODUCTION OF ROCK TYPE
Kind of
Stone
Granite
Traprock
Marble
Limestone and
Dolomite
Shell
Calcareous Marl
Sandstone, Quartz
and Quartzite
Other
Total
1972
1000 Short Tons
106,266
80,462
2,247
671,496
16,610
2,650
27,817
298
922,361
Percent
11-5
8.7
0.2
72.8
1.8
0.3
3.0
1.6
18
-------
Riprap is large irregular stone used chiefly in river and
harbor work and to protect highway embankments. Fluxing
stone is limestone, usually 4 to 6 inches in size, which is
used to form slag in blast furnaces and other metallurgical
processes. Terrazzo is sized material, usually marble or
limestone, which is mixed with cement for pouring floors,
which are smoothed down to expose the chips after the floor
has hardened. A small amount of guartzose rock is also used
for flux. Stucco dash consists of white or brightly colored
stoner 1/8 to 3/8 inches in size, for use in stucco facing.
The ability of ground limestone to significantly reduce the
acidity of soils has resulted in its widespread use in
agricultural processes.
The crushed stone industry is widespread and varied in size
of facilities and types of material produced. The size of
individual firms varies from small independent producers
with single facilities to large diversified corporations
with 50 or more crushed stone facilities as well as other
important interests. Facility capacities range from less
than 22,700 kkg/yr (25,000 tons/yr) to about 13.6 million
kkg/yr (15 million tons/yr). As Table 5 shows only about
5.2 percent of the commercial facilities are of a 816,000
kkg (900,000 ton) capacity or larger, but these account for
39.5 percent of the total output. At the other extreme,
facilities of less than 22,700 kkg (25,000 ton) annual
capacity made up 33.3 percent of the total number but
produce only 1.3 percent of the national total.
Geographically, the facilities are widespread with all
states reporting production. In general, stone output of
the individual States correlates with population and
industrial activity as shown by Figures 4 and 5. This is
true because of the large cost of shipment in relation to
the value of the crushed stone.
Most crushed and broken stone is presently mined from open
quarries, but in many areas factors favoring large-scale
production by underground mining methods are becoming more
frequent and more prominent. Surface mining equipment
varies with the type of stone, the production capacity
needed, size and shape of deposits, estimated life of the
operation, location of the deposit with respect to urban
centers, and other important factors. Ordinarily, drilling
is done with tricone rotary drills, long-hole percussion
drills including "down the hole" models, and churn drills.
Blasting in smaller operations may still be done with
dynamite, but in most sizable operations ammonium
nitrate-fuel oils mixtures (AN/FO), which are much lower in
cost, are used. Secondary breakage increasingly is done
with mechanical equipment such as drop hammers to minimize
blasting in urban and residential areas.
19
-------
TABLE 5
1973 SIZE DISTRIBUTION OF CRUSHED STONE PLANTS*
ANNUAL PRODUCTION
TONS
NUMBER OF
QUARRIES
TOTAL ANNUAL
PRODUCTION
1000 TONS
PERCENT
OF TOTAL
25,000
50,000
75,000
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
§ 25,000
- 49,999
- 74,999
- 99,999
- 199,999
- 299,999
- 399,999
- 499,999
- 599,999
- 699,999
- 799,999
- 899,999
§ 900,000
TOTAL
1,600
600
339
253
634
308
233
182
126
98
76
51
248
13,603
24,221
20,485
21,941
90,974
75,868
80,946
80,956
68,903
62,730
56,694
42,718
418,502
1.3
2.3
1.9
2.1
8.6
7.2
7.6
7.7
6.5
5.9
5.4
4.0
39.5
4,808
1,058,541
100.0
U.S. Deaprtment of the Interior
Bureau of Mines
Division of Nonmetallic Minerals
20
-------
FIGURE 4
CRUSHED GRANITE
1972/1 ,000,000 short tons
* Other producing States (total
National Total = 106.3
Data From: Minerals Yearbook - 1972, Vol. I
Table 11, p. 1T68
-------
to
to
FIGURE 5
CRUSHED LIMESTONE
AND DOLOMITE
1972/1,000,000 short tons
Pacific Islands = ,9
** Total stone - crushed & dimensional
* Other producing States (total = 8.2)
National total (excluding P.R. & territories) = 663.3
Data From: Mineral Yearbook - 1972, Vol. I
Table 13, p. 1170
-------
Underground operations are becoming more common as the
advantages of such facilities increase or are increasingly
recognized by the producers. Underground mines can be
operated on a year-round, uninterrupted basis; do not
require extensive removal of overburden; do not produce much
if any waste requiring subsequent disposal; require little
surface area which becomes of importance in areas of high
land cost and finally, greatly reduce the problems of
environmental disturbance and those of rehabilitation of
mined-out areas. An additional benefit from underground
operations, as evidenced in the Kansas City area, is the
value of the underground storage space created by the mine -
in many cases the sale or rental of the space produces
revenue exceeding that from the removal of the stone.
Loading and hauling equipment has grown larger as increasing
demand for stone has made higher production capaciti es
necessary. Track-mounted equipment is still used
extensively but pneumatic-tire-mounted hauling equipment is
predominant.
Crushing and screening facilities have become larger and
more efficient, and extensive use is made of belt conveyors
for transfer of material from the pits to the loading-out
areas. Bucket elevators are used for lifting up steep
inclines. Primary crushing is often done at or near the
pit, usually by jaw crushers or gyratories, but impact
crushers and special types may be used for nonabrasive
stone, and for stone which tends to clog the conventional
crushers. For secondary crushing a variety of equipment is
used depending on facility size, rock type, and other
factors. Cone crushers and gyratories are the most common
types. Impact types including hammer mills are often used
where stone is not too abrasive. For fine grinding to
produce stone sand, rod mills predominate.
For screening, inclined vibrating types are commonly used in
permanent installations, while horizontal screens, because
they require less space, are used extensively in portable
facilities. For screening large sizes of crushed stone,
heavy punched steel plates are used, while woven wire
screens are used for smaller material down to about
one-eighth of an inch. Air and hydraulic -separation and
classifying equipment is ordinarily used for the minus 1/8
inch material.
Storage of finished crushed stone is usually done in open
areas except for the small quantities that go to the
load-out bins. In the larger and more efficient facilities
the stone is drawn out from tunnels under the storage piles,
and the equipment is designed to blend any desired mixture
of sizes that may be needed.
23
-------
Oyster shells are found in shallow waters in great quantity,
and, being made of very pure calcium carbonate, they are
dredged for use in the manufacture of lime and cement. The
industry is large and active along the Gulf Coast,
especially at New Orleans, Lake Charles, Houston, Freeport,
and Corpus Christi.
In Florida, oyster shell was recovered from fossil beds
offshore on both Atlantic and Gulf coasts. Production in
1957 amounted to 1,364,000 kkg (1,503,964 tons), used
principally for road metal and a small amount as poultry
grit. This figure included coquina, a cemented shell rock
of recent but not modern geological time, which is dredged
for the manufacture of cement near Bunnell in Flagler
County. It is used widely on lightly traveled sand roads
along the east coast.
Clam shells used to be dredged from fresh water streams in
midwestern states for the manufacture of buttons, but the
developments in the plastics industry have impacted heavily.
Table 6 gives a breakdown of the end uses of crushed stone.
The majority of crushed stone is used in road base, cement
and concrete.
CONSTRUCTION SAND AND GRAVEL (SIC 1442)
Sand and gravel are products of the weathering of rocks and
thus consist predominantly of silica but often contain
varying amounts of other minerals such as iron oxides, mica
and feldspar. The term sand is used to describe material
whose grain size lies within the range of 0,065 and 2 mm and
which consists primarily of silica but may also include fine
particles of any rocks, minerals and slags. Gravel consists
of naturally occurring rock particles larger than about 4 mm
but less than 64 mm in diameter. Although silica usually
predominates in gravel, varying amounts of other rock
constituents such as mica, shale, and feldspar are often
present. Silt is a term used to describe material finer
than sand, while cobbles and boulders are larger than
gravel. The term "granules" describes material in the 2 to
4 nun size range. The descriptive terms and the size ranges
are somewhat arbitrary although standards have to some
extent been accepted. For most applications of sand and
gravel there are specifications for size, physical
characteristics, and chemical composition. For construction
uses, the specifications depend on the type of construction
roads (concrete or bituminous), dams, and buildings - the
geographic area, architectural standards, climate, and the
type and quality of sand and gravel available.
24
-------
Kind of utone tjr<;i<..jcc
2,517
2.6SO
3,598
18,579
16,068
3,966
37,877
5,696
10,048
4,036
6,1(32
97
3,718
106,266
182,930
27,140
100,173
49,977
26,993
139,257
38,704
71,647
12,935
7,250
339
4,752
124
101,304
28,858
1,670
1,030
24,728
395
4,199
876
2,964
635
4,243
1,794
560
18,930
671,496
1,090,707
44
83
862
203
1,047
8
2,247
25,005
2,092
1,613
351
8,744
951
3,290
2,213
1,014
52
343
23
Kind of stone mid vac Quantity
;iOUO (onn)
SANDSTONE, QUARTZ, AND QUART/. ITE
(continued)
Cttnt-nt nnd, Urns mnn«fncture 522
Ferroalllcon 227
Flux stout 1,102
Refractory Htone 211
Abrasives 45
Class 925
Other uses 3,100
Totol 26,817
Value (?1000) 57,994
SHELL
Concrete angregste (coarse)
Dense grodod voad base stone 1,675
Unspecified construction aggregate a.-d roadstone 3,281
Cement and lin-.e manufacture 5,67^
Other uses 5,98u
Total 16,610
Value (51000) 29,571
TRAFROCK
Agricultural purposes 444
Concrete aggregate (coarse) 6,643
Bituminous aggregate 11,469
Macadam aggregate 1,438
Dense graded road base stope 19,361
Surface treatrr.ent aggregate 5,341
Vnepecified construction aggregate and roadstone 23,811
Riprap and jetty stone 3,623
Rallr.td ballast 2,332
Filter stone LI?
Manufactured fine aggregate (stone sand) 231
Fill 1,686
Other uses 3,966
Total 80,462
Valup ($1000) 170,823
OTHER STOHE
Concrete aggregate (coarse) 1,159
Bituminous aggregate 2,202
Macadam aggregate 278
Dense graded raod base stone 3,051
Surface treatment aggregate 591
Unspecified construction aggregate and roadstone 2,911
Riprap and jetty stone 1,738
Railroad ballast —
Mineral fillers, extenders and whiting
Fill 578
Other uses 1,789
Total 14,298
Value ($1000) 24,442
TOTAL STOHE
Agricultural purposes 23,393
Concrete aggregate (coarse) 113,471
Bituminous Aggregate 82,560
Macadam aggregate 33,110
Lense graded road base stone 210,013
Surface treatment aggregate 51,.943
Unspecified construction aggregate and roadstone 113,406
Riprap and jetty atone 24,560
Railroad ballast 18,021
Filter stone 636
Manufactured fine aggregate (stone sand) 5,869
Terrazao and exposed aggregate 402
Cement manufacture 108,857
Lime manufacture 30,051
Bead-burned dolomite 1,670
Ferroellicor, • 1,257
Flux stone 25,830
Refractory stone 605
Chemical stone for alkali works 4,199
Spc.clal noes and products 1,071
Mineral fillers, extenders and whiting 4,423
Fill 6,630
CJflBB . 2,738
Expanded nlatc 1,270
Other uooa ' 31,394
Total 922,361
VoJup ($1000) 1,592,569
MlnoralH Ycttrttoofc, ]972, U.S. Ucpnrtmsnt of! tli« Interior
Bui.-an fif Klnnn
25
-------
Briefly, on a geographic-geologic basis, in the glaciated
areas in the northern States, and for a hundred miles or
more south of the limit of glacial intrusion, the principal
sand and gravel resources consist of various types of
outwash glacial deposits and glacial till. Marine terraces,
both ancient and recent geologically, are major sand and
gravel sources in the Atlantic and Gulf Coastal Plains.
River deposits are the most important sand and gravel
sources in several of the Southeastern and South Central
States. Abundant sand and gravel resources exist in the
mountainous areas and the drainage from the mountains has
created deposits at considerable distances from the initial
sources. Great Plains sand and gravel resources consist
mainly of stream-worked material from existing sediments.
On the West Coast, deposits consist of alluvial fans, river
deposits, terraces, beaches, and dunes. Figures 6 and 7
show the production and facility distribution for the United
States.
The sand and gravel industry, on the basis of physical
volume, is the largest nonfuel mineral industry; the value
of sand and gravel output is exceeded by that of only one
nonfuel mineral commodity, stone. Because of its widespread
occurrence and the necessity for producing sand and gravel
near the point of use there are more than 5,000 firms
engaged in commercial sand and gravel output, with no single
firm being large enough to dominate the industry. Facility
sizes range from very small producers of pit-run material to
highly automated permanent installations capable of
supplying as much as 3.6 million kkg (4 million tons) yearly
of closely graded and processed products; the average
commercial facility capacity is about 108,000 kkg/yr
(120,000 tons/yr). As seen from Table 7 about 40 percent of
all commercial facilities are of less than 22,600 kkg
(25,000 tons) capacity, but together these account for only
4 percent of the total commercial production. At the other
extreme, commercial operations with production capacities of
more than 907,000 kkg (1 million tons) account for less than
1 percent of the total number of facilities and for 12 to 15
percent of the commercial production.
Geographically the sand and gravel industry is concentrated
in the large rapidly expanding urban areas and on a
transitory basis, in areas where highways, dams, and other
large-scale public and private works are under construction.
Three-fourths of the total domestic output of sand and
gravel is by commercial firms, and one-fourth by Government-
and-contractor operations.
26
-------
FIGURE 6
SAND AND GRAVEL
PRODUCTION '
1972/1,000,000 short tons
National Total (excluding P.R.) = 913.2
Data From: Minerals Yearbook - 1972, Vol. I
Table 3, p. 1111-1112
Bureau of Mines
-------
N)
CO
FIGURE 7
SAND AND GRAVEL
PLANTS
1972
Data From: Minerals Yearbook - 1972
Vol U
Bureau of Mines
-------
TABLE 7
1972 Size Distribution of Sand and Gravel Plants
Production
Thousand Percent
Annual Production
(short tons)
Less than 25,000
25,000 to 50,000
50,000 to 100,000
100,000 to 200,000
200,000 to 300,000
300,000 to 400,000
400,000 to 500,000
500,000 to 600,000
600,000 to 700,000
700,000 to 800,000
800,000 to 900,000
900,000 to 1,000,000
1,000,000 and over
Plants
Number
1,630
850
957
849
400
217
134 .
79
71
56
26
27
88
short
tons
17,541
30,508
68,788
121,304
97,088
75,157
59,757
42,924
46,036
41,860
22,310
25,666
136,850
of
total
2.2
3.9
8.8
15.4
12.4
9.6
7.6
5.5
5.9
5.3
2.8
3.3
17.3
Total
5,384
785,788
100.0
Minerals Yearbook, 1972, U.S. Department of the Interior,
Bureau of Mines, Vol I, page 1120
29
-------
California leads in total sand and gravel production with
output more than double that of any other State, Production
for the State in 1968 was 113 million kkg (125 million
tons), or 14 percent of the national total. Three of the 10
largest producing firms are located in California. The next
five producing States with respect to total output all
border on the Great Lakes, where ample resources, urban and
industrial growth, and low-cost lake transportation are all
favorable factors.
Mining equipment used varies from small, simple units such
as tractor-mounted high-loaders and dump trucks to
sophisticated mining systems involving large power shovels,
draglines, bucket-wheel excavators, belt conveyors and other
components. Increasingly, mining systems are being designed
to provide for most efficient and economical subsequent land
rehabilitation. Sand and gravel is also dredged from river
and lake bottoms rich in such deposits.
Processing may consist of simple washing to remove clay and
silt and screening to produce two or more products or it may
involve more complex heavy medium separation of slate and
other lightweight impurities, and complex screening and
crushing equipment designed to produce the optimum mix of
salable sand and gravel sizes. Conveyor belts, bucket
elevators, and other transfer equipment are used
extensively. Ball processing is often required for
production of small-size fractions of sand. Permanent
installations are built when large deposits are to be
operated for many years, Semiportable units are used in
many pits which have an intermediate working life. Several
such units can be tied together to obtain large initial
production capacity or to add capacity as needed. In areas
where large deposits are not available, use is made of
mobile screening facilities, which can be quickly moved from
one deposit to another without undue interruption or loss of
production. Table 8 breaks down the end uses of sand and
gravel.
INDUSTRIAL SAND (SIC 1446)
Industrial sands includes those types of silica raw
materials that have been segregated and refined by natural
processes into nearly monomineralic deposits and hence, by
virtue of their high degree of purity, have become the
sources of commodities having special and somewhat
restricted commercial uses. In some instances, these raw
materials occur in nature as unconsolidated quartzose sand
or gravel and can be exploited and used with very little
preparation and expense. More o ften, they occur as
sandstone, conglomerate quartzite, quartz mica schist, or
massive igneous quartz which must be crushed, washed.
30
-------
Table 8
1972 Uses of Sand and Gravel
Use Quantity
1000 kkg 1000 short tons
Building
Sand 170,329 187,794
Gravel 139,001 153,254
Paving
Sand 119,182 131,402
Gravel 254,104 280,159
Fill
Sand 44,050 48,567
Gravel 39,416 43,458
Railroad Ballast
Sand 948 1,045
Gravel 2,022 2,229
Other
Sand 8,685 9,575
Gravel 11,682 12,880
Total 789,419 870,363
Value ($1000) 1,069,374
Value ($/Quantity) 1.35 1.23
Minerals Yearbook, 1972, U.S. Department of the Interior
Bureau of Mines
31
-------
screened, and sometimes chemically treated before
commodities of suitable compositional and textural
characteristics can be successfully prepared.
Industrial silica used for abrasive purposes falls into
three main categories: (a) blasting sand; (b) glass-
grinding sand; and (c) stonesawing and rubbing sand.
Figure 8 locates the domestic industrial sand deposits.
Table 9 gives the breakdown of the uses of industrial sand.
Blasting sand is a sound closely-sized quarts sand which,
when propelled at high velocity by air, water, or controlled
centrifugal force, is effective for such uses as cleaning
metal castings, removing paint and rust, or renovating stone
veneer. It is commonly referred to as sand blast sand.
Chief sources of blasting sands are in Ohio, Illinois,
Pennsylvania, West Virginia, New Jersey, California,
Wisconsin, South Carolina, Georgia, Florida, and Idaho.
Glass-grinding sand is clean, sound, fine to medium-grained
silica sand, free from foreign material and properly sized
for either rough grinding or semifinal grinding of plate
glass. Raw materials suitable for processing into these
commodities comprise deposits of clean, sound sand,
sandstone, and quartzite. As this commodity will not stand
high transportation charges, sources of this material near
sheet and plate glass facilities are the first to be
exploited.
Stone-sawing and rubbing sand is relatively pure, sound,
well-sorted, coarse-grained, siliceous material free from
flats and fines used for sawing and rough-grinding dimension
stone. Neither textural nor quality specifications are
rigorous on this type of material as long as it is high in
free silica and no clay, mica, or soft rock fragments are
present. Chert tailings, locally known as chats in certain
mining districts, are used successfully in regions close to
the source of such materials. River terrace sand, and
glacial moraine materials which have been washed and
screened to remove oversize and fines, are often employed.
Several important marble and granite producing districts are
quite isolated from sources of clean silica sand and are
forced to adapt to less efficient sawing and grinding
materials in order to eliminate the high cost of long
freight hauls.
Glass-melting and chemical sands are quartz sands of such
high purity that they are essentially monomineralic;
permissible trace impurities are variable according to use;
grain shape is not a critical factor, but size frequency
distribution can vary only between narrow limits.
32
-------
FIGURE 3
INDUSTRIAL SAND DEPOSITS
From Glass Sand and Abrasives chart-pg.184
The National Atlas of The USA
USGS-1970
-------
Table 9
1972 Uses of Industrial Sand
Use
Quantity
1000 kkg 1000 short tons
Value
$/kkg $/ton
Unground
Glass
Molding
Grinding and polishing
Blast sand
Fire or furnace
Engine (RR)
Filtration
Oil Hydrofrac
Other
Ground Sand
Total
9821
6822
238
972
638
545
212
256
3187
4092
26784
10828
7522
262
1072
703
601
234
282
3514
4512
29530
4.20
3.64
3.08
6.46
3.52
2.54
5.53
4.18
3.73
81
30
79
86
3.19
30
02
79
3.38
5.26 4.77
4.20 3.81
Minerals Yearbook, 1972, U.S. Department of the Interior,
Bureau of Mines
34
-------
Appropriate source materials are more restricted than for
any other industrial silica commodity group. Because the
required products must be of superlative purity and
consequently are the most difficult and expensive to
prepare, they command higher prices and can be economically
shipped greater distances than nearly any other class of
special sand.
To qualify as a commodity in this field the product must be
a chemically pure quartz sand essentially free of
inclusions, coatings, stains, or detrital minerals.
Delivery to the customer in this highly refined state must
be guaranteed and continuing uniformity must be maintained.
At the present time the principal supply of raw materials
for these commodities comes from two geological formations.
The Oriskany quartzite of Lower Devonian age occurs as
steeply dipping beds in the Appalachian Highlands.
Production, in order of importance, is centered in West
Virginia, Pennsylvania, and Virginia. The St. Peter
sandstone of Lower Ordovician age occurs as flatlying beds
in the Interior Plains and Highlands and is exploited in
Illinois, Missouri, and Arkansas.
Metallurgical pebble is clean graded silica in gravel sizes,
low in iron and alumina, used chiefly as a component in the
preparation of silicon alloys or as a flux in the
preparation of elemental phosphorus. A quartzite or quartz
gravel, to qualify as a silica raw material chemically, must
meet rigorous specifications. Metallurgical gravel is no
exception and in the production of silicon alloys, purity is
paramount. Such alloys as calcium-silicon, ferrosilicon,
silicon-chrome, silicon copper, silicomanganese, and
silicon-titanium are the principal products prepared from
this material. The better deposits of metallurgical grade
pebble occur principally as conglomerate beds of
Pennsylvanian age, and as .gravelly remnants of old river
terraces developed from late Tertiary to Recent times.
Significant producing areas are in the Sharon' conglomerate
member of the Pottsville formation in Ohio. Silica pebble
from the Sewanee conglomerate is produced in Tennessee for
alloy and flux use. Past production for metallurgical use
has come from the Olean conglomerate member of the
Pottsville formation in New York, and the Sharon
conglomerate member of the Pottsville formation in
Pennsylvania. Production from terrace gravels comes from
North Carolina, Alabama, South Carolina, and Florida in
roughly decreasing order of economic importance. Marginal
deposits of coarse quartzose gaavel occur in Kentucky.
Terrace deposits of vein quartz gravel in California have
supplied excellent material for ferrosilicon use in the
past.
35
-------
Industrial silica used principally for its refractory
properties in the steel and foundry business is of several
types: (a) core sand; (b) furnace-bottom sand; (c) ganister
mix; (d) naturally bonded molding sand; (e) processed
molding sand; (f) refractory pebble; and (g) runner sand.
A foundry sand used in contact with molten metal must
possess a high degree of refractoriness; that is, it must
resist sintering which would lead to subsequent adhesion and
penetration at the metal-sand interface. To be used
successfully as a mold or a core into which or around which
molten metal is cast, it also must be highly permeable.
This allows escape of steam and gases generated by action of
the hot metal upon binders and additives in the mold or core
materials. Such a sand must have sufficient strength under
compression, shear, and tension to retain its molded form
not only in the green state at room temperature, but also
after drying and baking, and later at the elevated
temperatures induced by pouring. Finally, it must be
durable and so resist deterioration and breakdown after
repeated use.
Core sand is washed and graded silica sand low in clay
substance and of a high permeability, suitable for core-
making in ferrous and nonferrous foundry practice.
Furnace bottom sand is unwashed and partially aggregated
silica sand suitable for lining and patching open hearth and
electric steel furnaces which utilize an acid process. The
term fire sand is often employed but is gradually going out
of use. As for core sands, source materials for this
commodity are quartz sands and sandstones which occur within
reasonable shipping distances of steelmaking centers, chief
production centers are in Illinois, Ohio, Michigan, West
Virginia, Pennsylvania, and New Jersey.
Ganister mix is a self-bonding, ramming mixture composed of
varying proportions of crushed quartzose rock or quartz
pebble and plastic fire clay, suitable for lining, patching,
or daubing hot metal vessels and certain types of furnaces.
It is variously referred to as Semi-silica or Cupola daub.
As in molding sands, there are two broad classes of
materials used for this purpose. One is a naturally-
occuring mixture of quartz sand and refractory clay, and the
other is a prepared mixture of quartz in pebble, granule, or
sand sizes bonded by a clay to give it plasticity.
Commercial ganister mix occuring naturally is exploited in
two areas in California and one in Illinois. The California
material contains roughly 75 percent quartz sand and lies
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between the 50 and 200 mesh sieves; the remaining portion is
a refractory clay.
The bulk of this commodity is produced in the East and Mid-
West where the foundry and steel business is centered. A
large volume is produced from pebbly phases of the Sharon
conglomerate in Ohio. The Veria sandstone of Mississippian
age is crushed and pelletized for this purpose in Ohio. In
Pennsylvania it is prepared from the Chickies quartzite of
Lower Cambrian age, although some comes from a pebbly phase
of the Oriskany. In Massachusetts, a post-Carbonif erous
hydrothermal quartz is used and in Wisconsin, production
comes from the Pre-Cambrian Baraboo quartzite.
Naturally bonded molding sand is crude silica sand
containing sufficient indigenous clay to make it suitable
for molding ferrous or non-ferrous castings. Natural
molding sands are produced in New York, New Jersey, and
Ohio. Coarse-grained naturally bonded molding sand with a
high permeability suitable for steel castings is produced to
some extent wherever the local demand exists. Large
tonnages are mined from the Connoquenessing and Homewood
Sandstone members of the Pottsville formation in
Pennsylvania; the St. Peter sandstone in Illinois, and the
Dresbach sandstone of Upper Cambrian age in Wisconsin.
Processed molding sand is washed and graded quartz sand
which, when combined with appropriate bonding agents in the
foundry, is suitable for use for cores and molds in ferrous
and nonferrous foundry practice. Source materials which
account for the major tonnage of processed molding sand are
primarily the St. Peter formation in Illinois and Missouri,
the Oriskany quartzite in Pennsylvania and West Virginia,
the basal Pottsville in Ohio and Pennsylvania, and the
Tertiary sands in New Jersey,
Refractory pebble is clean graded silica in gravel sizes,
low in iron and alumina, used as a raw material for
superduty acid refractories.
With few exceptions, bedded conglomerate and terrace gravel
furnish the bulk of the raw material. Silica pebble in the
Sharon conglomerate in Ohio, and the Mansfield formation in
Indiana, are utilized. Significant production comes from a
coarse phase of the Oriskany in Pennsylvania as well as from
deposits of Bryn Mawr gravel in Maryland. Potential
resources of conglomerate and terrace gravel of present
marginal quality occur in other areas of the United States.
Other quartzitic formations are currently utilized for
superduty refractory work. Notable production comes from
the Baraboo quartzite in Wisconsin, the Weisner quartzite in
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Alabama, and from quartzite beds in the Oro Grande series of
sediments in California.
Runner sand is a crude coarse-grained silica sandr
moderately high in natural clay bond, used to line runners
and dams on the casting floor of blast furnaces. Runner
sand is also used in the casting of pig iron. The term
Casthouse sand also is used in the steel industry.
Coal-washing sand is a washed and graded quartz sand of
constant specific gravity used in a flotation process for
cleaning anthracite and bituminous coal.
Filter media consist of washed and graded quartzose gravel
and sand produced under close textural control, for removal
of turbidity and bacteria from municipal and industrial
water supply systems.
Hydraulic-fracturing sand is a sound, rounded, light-colored
quartz sand free of aggregated particles and possessing high
uniformity in specified size ranges which, when immersed in
a suitable carrier and pumped under great pressure into a
formation, increases fluid production by generating greater
effective permeability. It is commonly referred to as
Sandfrac sand in the trade.
GYPSUM (SIC 1492)
Gypsum is a hydrated calcium sulfate (CaSO4_«2H2O) generally
found as a sedimentary bed associated with limestone,
dolomite, shale or clay in strata deposited from early
Paleozoic to Recent. Most deposits of gypsum and anhydrite
(CaSO4) are considered to be chemical precipitates formed
from saturated marine waters. Deposits are found over
thousands of square miles with thicknesses approaching 1800
feet - for example the Castle anhydrite of Texas and New
Mexico. Field evidence indicates that most deposits were
originally anhydrite which were subsequently subjected by
surface hydration to gypsum.
Commercial gypsum deposits are found in many states of the
United States with the leading producers being California,
Iowa, Nevada, New York, Texas and Michigan with lesser
amounts being produced in Colorado, and Oklahoma. Figure 9
shows the distribution of facility sizes. The ore is mined
underground and from open pits with the latter being the
more general method because of lower costs. In 1958, 44 of
the 62 mining operations were open pits, while three of the
remainder were combinations of open pit and underground
mines. In quarrying operations, stripping of the overburden
is usually accomplished with drag lines or with tractor
equipment. Quarry drilling methods vary with local
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FIGURE 9
GYPSUM OPERATIONS
Data From: Salines chart - p. 181
The National Atlas of USA
USGS -.1970
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conditions, blasting is accomplished with low-speed, low
density explosives. The fragmented ore is loaded with power
shovels onto truck or rail transport to the processing
facility. Generally, the primary crushing is done at the
quarry site. Second-stage crushing is usually accomplished
with gyratory units and final crushing is almost invariably
by hammermills. The common unit for grinding raw gypsum is
the air-swept roller process facility. Ground gypsum is
usually termed "land plaster" in the industry because in
this form, sacked or in bulk, it is also sold for
agricultural purposes.
In recent years, a trend has started towards the
beneficiation of low-grade gypsum deposits where strategic
location has made this economically feasible. The
heavy-media method has been introduced in two Ohio
facilities; screening and air separation have been employed
for improving purity in a limited number of other
operations. The tonnage of gypsum thus beneficiated is
still a small part of the total output.
Most mined and crushed gypsum is calcined to the
hemi-hydrate stage by one of six different methods
kettles, rotary, calciner, hollow-flight screw conveyers,
impact grinding and calcining mills, autoclaves, and beehive
ovens. The calcined gypsum is used for various types of
plasters, board and block, preformed gypsum tile, partition
tile, and roof plank. By far the largest use of calcined
gypsum (stucco) takes place in the manufacture of board
products. Gypsum board is a sandwich of gypsum between two
layers of specially prepared paper. It is manufactured in
large machines by mixing the prepared stucco with water,
foam and other ingredients and then poured upon a moving,
continuous sheet of special heavy paper. Under "master
rolls" the board is formed with the bottom paper receiving
the wet slurry and another continually moving sheet of paper
being placed on top, compacted, cut, and dried.
ASPHALTIC MINERALS
The bitumens are defined as mixtures of hydrocarbons of
natural or pyrogenous origin or combinations of both,
frequently accompanied by their derivatives, which may be
gaseous, liquid, semisolid or solid and which are completely
soluble in carbon disulfide. Oil shale and like materials
which are mined for their energy content are not covered by
this subcategory.
The principal bituminous materials of commercial interest
are:
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(1) Native asphalts, solid or semisolid, associated with
mineral matter such as Trinidad Lake asphalt.
Selenitza, Boeton and Iraq asphalts.
(2) Native Asphaltites, such as gilsonite, grahamite and
glance pitch, conspicuous by their hardness, brittleness
and comparatively high softening point.
(3) Asphaltic bitumens obtained from non-asphaltic and
asphaltic crude petroleum by distillation, blowing with
air and the cracking of residual oils.
(4) Asphaltic pyrobitumens of which wurtzilite and elaterite
are of chief interest industrially as they depolymerize
upon heating, becoming fusible and soluble in contrast
to their original properties in these respects.
(5) Mineral waxes, such as ozokerite, characterized by their
high crystallizable paraffine content.
There are several large deposits of bituminous sand,
sandstone and limestone in various parts of the world but
those of most commercial importance are located in the
United States and Europe.
Commercial deposits of bituminous limestone or sandstone in
the United States are found in Texas, Oklahoma, Louisiana,
Utah, Arkansas, California, and Alabama. The bitumen
content in these tends to run from 4 to 14 percent. Some of
the sandstone in California has a higher content, about 15
percent, and a deposit in Oklahoma contains as high as 18
percent. The Uvalde County, Texas deposit is a conglomerate
containing 10 to 20 percent of hard bitumen in limestone
which must be mixed with a softer petroleum bitumen and an
aggregate to produce a satisfactory paving mixture.
Commercially, rock asphalt in this country is used almost
exclusively for the paving of streets and highways.
Rock asphalt is mined from open quarries by blasting and is
reduced to fines in a series of crushers and then pulverized
in roller mills to the size of sand grains varying from 200
mesh to 1/4 inch in size.
Gilsonite, originally known as uintaite is found in the
Uintah basin in Utah and Colorado. Gilsonite is a hard,
brittle, native bitumen of variable but high softening
point. It occurs in almost vertical fissures in rock
varying in composition from sandstone to shale. The veins
vary in width from 0.025 to 6.7 meters (1 in to 22 ft> and
in length from a few kilometers to as much as 48 km (30 mi).
The depth varies from a few meters to over 460 m (1500 ft).
Mining difficulties, such as the creation of a very fine
dust which in recent years resulted in two or three serious
explosions, and the finding of new uses for gilsonite
nece s sitated one company to supplement the conventional
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pick-and-shovel method by the hydraulic system. However,
on some properties the mining is still done by hand labor,
compressed air. picks, etc.
Grahamite occurs in many localities in the United States and
in various countries throughout the world but never in large
amounts. The original deposit was discovered in West
Virginia but has long been exhausted. Deposits in Oklahoma
were exploited to a great extent for years but little is now
mined in commercial quantities.
The material differs from gilsonite and glance pitch having
a much higher specific gravity and fixed carbon, and does
not melt readily but intumesces on heating.
Glance pitch was first reported on the island of Barbados.
The material is intermediate between gilsonite and
grahamite. It has a specific gravity at 60°F of 1.09 to
1.15, a softening point (ring and ball) of 275° to 400°F and
a fixed carbon of 20 to 30 percent.
Wurtzilite, sometimes referred to as elaterite, is one of
the asphaltic pyrobitumens and is distinguished by its
hardness and infusibility. It is found in Uintah County,
Utah, in vertical veins varying from 2.5 cm to 63.5 cm (1 in
to 25 in) in width and from a. few hundred meters to 4.8 km
(3 miles) in length. It is used in the manufacture of
paints, varnishes, as an extender in hard rubber compounds,
and various weatherproofing and insulating compounds.
Ozokerite is a solid waxlike bitumen the principal supply of
which is found in the Carpathian mountains in Galicia. A
small amount of it is also found in Rumania, Russia and the
state of Utah. The hydrocarbons of which it is composed are
solids, resembling paraffin scale and resulted from
evaporation and decomposition of paraffinaceous petroleum.
It occurs in either a pure state or it may be mixed with
sandstone or other mineral matter. The material is mined by
hand and selected to separate any material containing
extraneous matter. Ozokerite when refined by heating to
about 182°C (360°F), treated with sulfuric acid, washed with
alkali and filtered through fuller's earth is called
"ceresine."
ASBESTOS (SIC 1499)
Asbestos is a broad term that is applied to a number of
fibrous mineral silicates which are incombustible and which,
by suitable mechanical processing, can be separated into
fibers of various lengths and thicknesses. There are
generally six varieties of asbestos that are recognized: the
finely fibrous form of serpentine known as chrysotile and
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five members of the amphibole group, i.e., amosite,
anthophyllite, crocidolite, tremolite, and actinolite.
Chrysotile, which presently constitutes 93 percent of
current world production, has the empirical formula
3MgO.2SiO2-2H2O and in the largest number of cases is
derived from deposits whose host rocks are ultrabasic in
composition. The bulk of chrysotile production comes from
three principal areas: the Eastern Townships of Quebec in
Canada, the Bajenova District in the Urals of USSR and from
south central Africa. The ore-body of greatest known
content in the United states is found in the serpentine
f ormati on of Northern Vermont which i s part o f the
Appalachian belt extending into Quebec. Figure 10 shows the
domestic asbestos deposits.
In North America the methods of asbestos mining are (1) open
quarries, (2) open pits with glory holes, (3) shrinkage
stoping, and (4) block caving; the tendency is toward more
underground mining. In quarrying, the present trend is to
work high benches up to 46 meters (150 feet) high and blast
down 91,000 kkg (100,000 tons) or more of rock at a shot.
An interesting feature of asbestos mining is that no wood
may be used for any purpose unless it is protected, because
it is impossible to separate wood fiber from asbestos in
processing.
Since the fiber recovery averages only 5 to 6 percent" of the
rock mined, very large tonnages must be handled - a capacity
of 910 kkg/day (1,000 tons/day) is about the minimum for
profitable operation.
Milling methods used at the various mills vary in detail,
but they are nearly all identical in principle. The objects
of processing are to recover as much of the original fiber
as possible, free from dirt and adhering rock; to expand and
fluff up the fiber; to handle the ore as gently as possible
to minimize the reduction in fiber length by attrition; and
to grade the fibers into different length groups best suited
to use requirements. The general method in use is (1)
coarse crushing in jaw or gyratory crushers, sometimes in
two stages, to 3.8 to 5.1 cm (1-1/2 to 2 in); (2) drying to
1 percent or less moisture, in rotary or vertical
inclined-plane driers; (3) secondary crushing in short head
cone crushers, gyratories, or hammer mills; (4) screening,
usually in flat shaking or gyratory screens; (5)
fine-crushing and fiberizing in stages, each stage followed
by screening, during which air suction above the screens
effects separation of the fiber from the rock; (6)
collection of the fiber in cyclone separators, which also
remove the dust; (7) grading of fibers in punched-plate
trommel screens; (8) blending of products to make
specification grades; and (9) bagging for shipment.
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FIGURE 10.
ASBESTOS DEPOSITS
From Minor Industrial Minerals chart-pg.184
The National Atlas of The USA
USGS-1970
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Fiberiz ing or opening up -the bundles of fiber (step 5) is
done in a special type of beater or impact process facility
designed to free the fiber from the rock and fluff up the
fiber without reduction in fiber length.
The screening operations are perhaps the most critical. The
air in the exhaust hoods over each screen must be so
adjusted that only the properly fiberized material will be
lifted, leaving the rock and unopened fiber bundles for
further fiberizing. The air system uses 20 to 25 percent of
the total power consumed in a process facility.
WOLLASTONITE (SIC 1499)
Wollastonite is a naturally occurring, fibrous calcium
silicate, CaSiO3, which is found in metamorphic rocks in New
York and California, as well as several foreign locations.
In the U.S. the mineral is mined only in New York.
The material is useful as a ceramic raw material, as filler
for plastics and asphalt products, as filler and extender
for paints, and in welding rod coatings. Due to its
fibrous, non-combustible nature, wollastonite is also being
considered as a possible substitute for asbestos in a number
of product situations in which asbestos is objectionable.
Wollastonite ore is mined by underground room and pillar
methods and trucked to the processing facility. The ore is
crushed in three stages, screened, dried, purified of garnet
and other ferro-magnesiurn impurities via high-intensity
magnetic separation and then ground to the desired product
size.
LIGHT WEIGHT AGGREGATE MINERALS (SIC 1499)
PERLITE
Perlite is a natural glassy rhyolitic rock, essentially a
metastable amorphous aluminum silicate, with an abundance of
spherical or convolute cracks which cause it to break into
small pearl-like masses usually less than a centimeter in
diameter, formed by the rapid cooling of acidic lavas.
Since natural geological processes tend to work towards
devitrification by progressive recrystallization and loss of
water, most useful deposits of vitrified lava will be in
recent lava flows of Tertiary or Quarternary age. Thus,
most of the significant deposits of perlite in the United
States are found in the Western states where active
volcanism was recent enough that the perlite deposits are
preserved. At the present time, the most important
commercial deposit is in New Mexico.
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Mining operations are open pit in locations chosen so that
little overburden removal is required and where topographic
factors are favorable for drainage and haulage of the crude
ore. The ore is mined by loosening the perlite with a
ripper to be picked up with a pan scraper. In some cases
fragmentation is accomplished by blasting followed by a
power shovel loading.
Milling proceeds by crushing in a jaw crusher and secondary
roll crusher with the normal screening operations. The
sized ore, after removal of fines which constitute roughly
25 percent of the process facility feed, is dried in a
rotary kiln to a residual moisture content below 1 percent,
and sent to storage for subsequent shipment to final
processors.
The commercial uses of perlite are all predicted on the
properties of expanded perlite. The glassy nature of the
natural material, coupled with the inclusion of considerable
moisture, when rapidly heated to 850-1100°C, results in the
rapid evolution of steam within the softened glass, causing
an explosive expansion of the individual fragments and
producing a frothy mass having 15 to 20 times the bulk of
original material. In commercial parlance, the term perlite
is applied to both the crude ore and the expanded product.
Approximately 70 percent of consumption is as an aggregate
for plaster, concrete and for prefabricated insulating board
wherein the perlite inclusion increases the fireproof rating
of aggregate plaster as well as yielding a significant
reduction in weight. The fact that perlite is relatively
chemically inert and relatively incompressible along with
the large surface area to volume ratios, makes it useful as
an important filter-aid material in the treatment of
industrial water and in the beverage, food and
pharmaceutical processing industry.
The environmental problems associated with the mining and
processing of perlite are almost entirely associated with
the excessive amount of fines.
PUMICE
Pumice is a rhyolitic (the volcanic equivalent of a granite)
glassy rock of igneous origin in which expanded gas bubbles
have distended the magma to form a highly vesicular
material. Pumicite has the same origin, chemical
composition and glassy structure as pumice but during
formation the pumicite was blown into small particles, hence
the distinction is largely one of particle size in that
pumicite has a particle size of less than 4 mm in diameter.
Commercial usage has resulted in the generic term pumice
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being applied to all of the various rocks of volcanic ash
origin.
The chemical composition of pumice varies from 72 percent
silica, 14 percent alumina and 4 percent combined calcium,
magnesium and iron oxides for the most acidic types to
approximately 45 percent silica, 16 percent alumina, and 30
percent combined calcium, magnesium, and iron oxides for the
most basic types.
The distribution of pumice is world wide, but due to meta-
morphism only those areas of relatively recent volcanism
yield pumice deposits of commercial importance. One great
belt of significant deposits borders the Pacific Ocean; the
other trends generally from the Mediterranean Sea to the
Himalayas and thence to the East Indies where it intersects
the first belt. The largest producers within the United
States are found in California and Idaho.
Mining operations are currently by open pit methods with the
overburden removed by standard earth moving equipment.
Since most commercial deposits of pumice are unconsolidated,
bulldozers, pan scrapers, draglines or power shovels can be
used without prior fragmentation.
When the mined pumice is used for railroad ballast or road
construction, processing required consist of simple crushing
and screening. Preparation for aggregate usually follows a
similar procedure but with somewhat more involved sizing to
produce a product conforming to rigorous specifications.
Occasionally, the ore requires drying in rotary dryers
either before or after crushing. Pumice prepared for
abrasive use requires additional grinding followed by sizing
via screening or air classification.
VERMICULITE
Vermiculite is the generic name applied to a family of
hydrated-ferro-magnesium-aluminum silicates which, in the
natural state have a characteristic micaceous habit and
which readily split into their laminaie which are soft,
pliable, and inelastic. Vermiculite deposits are generally
associated with ultrabasic igneous host rocks such as
pyroxenite or serpentine from which the Vermiculite seems to
have been formed by hydro-thermal activity. Biotite and
phlogopite mica, which frequently occur with vermiculite,
are considered to have a similar origin.
When heated rapidly, to temperatures of the order of
1050-1100°C, vermiculite exfoliates by expanding at right
angles to the cleavage into long wormlike pieces with an
increase in bulk of from 8 to 12 times. The term
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vermiculite is applied berth to the unexpanded mineral and to
the commercial expanded product.
The bulk of domestically mined vermiculite comes either from
the extensive deposit at Libby, Montana or from the group of
deposits near Enoree, South Carolina, Mining operations are
by open pit with removal of alluvial overburden accomplished
by tractor-driven scrapers. The ore can be dug directly by
power shovel or dragline excavator. Dikes or barren host
rock require fragmentation by drilling and blasting prior to
removal.
Ore beneficiation is accomplished by wet processing
operations using hammer mills, rod mills, rake classifiers,
froth flotation, cyclones, and screens. Centrifuges and
rotary driers are used to remove excess moisture following
beneficiation.
Exfoliation is carried out in vertical furnaces wherein the
crude, sized vermiculite is top fed and maintained at
temperatures from 900-1100°C for 4 to 8 seconds. The
expanded product is removed by suction fans and passed
through a classifier system to collect the product and to
remove excessive fines.
MICA (SIC 1499)
Mica is a group name for a number of complex hydrous
potassium aluminum silicate minerals differing in chemical
compositions and in physical properties but which are all
characterized by excellent basal cleavage that facilitates
splitting into thin, tough, flexible, elastic sheets. There
are four principal types of mica named for the most common
mineral in each type - muscovite, phlogopite, biotite and
lepidolite with muscovite (potassium mica) being
commercially the most important. Mica, for commercial
convenience, is broken down into ten broad classifications;
sheet mica which consists of relatively flat sheets
occurring in natural books or runs, and flake and scrap mica
which includes all other forms.
Muscovite sheet mica is recovered only from pegmatite
deposits where books or runs of mica occur sporadically as
crystals which are approximately tabular hexagons ranging
from a few centimeters to several meters in maximum
dimension. Mica generally occurs as flakes of small
particle size in many rocks. In addition, the mica content
of some schists and kaolins is sufficiently high to justify
recovery as scrap mica.
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Domestic mica mining has been confined mainly to pegmatites
in a few well-defined areas of the country. The largest
area extends from central Virginia southward through western
North and South Carolina and east-central Alabama. A second
area lies discontinuously in the New England States, where
New Hampshire, Connecticut, and Maine each possess mica
bearing pegmatites. A third region comprises districts in
the Black Hills of South Dakota and in Colorado, Idaho, and
New Mexico. Additional sources of flake mica have been made
available through the development of technology to extract
small particle mica from schists and other host rocks.
Deposits containing such mica are available throughout the
U.S.
Sheet mica mines are usually small-scale operations. Open
pit mining is used when economically feasible, but many mica
bearing pegmatites are mined by underground methods. During
mining care must be taken to avoid drilling through good
mica crystals. Only a few holes are shot at one time to
avoid the destruction of the available mica sheet.
Presently there is no significant quantity of sheet mica
mined in the U.S. Larger scale quarrying methods are used
to develop deposits for the extraction of
small-particle-size mica and other co-product minerals.
Flake mica that is recovered from pegmatites, schist, or
other rock is obtained by crushing and screening the host
rock and additional beneficiation by flotation methods in
order to remove mica and other co-product minerals. Then it
is fed to an oil-fired rotary dryer. The dryer discharge
goes to a screen from which the fines can go to waste or be
saved for further recovery.
Raw material for ground mica is obtained from sheet mica
processing operations, from crushing and processing of
schists, or as a coproduct of kaolin or feldspar production.
Buhr mills, rodmills, or high-speed hammer mills have been
used for dry-grinding mica. The process facility is in a
circuit with an air separator which returns any oversize
material for additional grinding and which discharges the
fines to a screening operation. The various sized fractions
are bagged for marketing. The ground mica yield from
beneficiated scrap runs 95 to 96 percent.
"Micronized" mica is produced in a special type of
dry-grinding machine, called a Micronizer. This ultrafine
material is produced in a disintegrator that has no moving
parts but uses jets of high-pressure superheated steam or
air to reduce the mica to micron sizes. This type of mica
is produced in particle size ranges of 10 to 20 microns and
5 to 10 microns.
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Wet-ground mica is produced in chaser-type mills to preserve
the sheen or luster of the mica. This process facility
consists of cylindrical steel tank that is lined with wooden
blocks laid with the end grain up. Wooden rollers are
generally used, which revolve at a slow rate of 15 to 30
revolutions per minute. Scrap goes to the mill, where water
is added slowly to form a thick paste. When the bulk of the
mica has been ground to the desired size, the charge is
washed from the process facility into settling bins where
gritty impurities sink. The ground mica overflows to a
settling tank and is dewatered by centrifuging and steam
drying. The final product is obtained by screening on
enclosed multiple-deck vibrating screens, stored and then
bagged for shipment.
The major environmental problem in processing flake mica is
the disposal of overburden material and flotation tailings,
and reconditioning of unused or abandoned mine sites.
Mining generally occurs away from highly urbanized areas,
and land use conflicts are minor problems.
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SECTION IV
INDUSTRY CATEGORIZATION
INTRODUCTION
In the development of effluent limitations guidelines and
recommended standards of performance for new sources in a
particular industry, consideration should be given to
whether the industry can be treated as a whole in the
establishment of uniform and equitable guidelines for the
entire industry or whether there are sufficient differences
within the industry to justify its division into categories.
For this segment of the mineral mining and processing
industry, which includes fifteen mineral products, the
following factors were considered as possible justifications
for industry categorization and subcategorization:
1) manufacturing processes;
2) raw materials
3) pollutants in effluent waste waters;
4) product purity;
5} water use volume;
6) facility size;
7) facility age; and
8) facility location.
INDUSTRY CATEGORIZATION
The first categorization step was to segment the mineral
mining and processing industry according to product use.
Thus, this volume. Volume Ip is "Mining of Minerals for the
Construction Industry," Volume II is "Mining of Minerals for
the Chemical and Fertilizer Industry," and. Volume III is
"Mining of Clay, Ceramic r Refractory, and Miscellaneous
Minerals." The reason for this is twofold. First the
industries in each volume generally have the same waste
water treatment problems. Secondly, this division results
in development documents that are not so big that the reader
may easily forget earlier points as he reads from section to
section.
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The first cut in subcategorization was made on a commodity
basis. This was necessary because of the large number of
commodities and in order to avoid insufficient study of any
one area. Furthermore, the economics of each commodity
differs and an individual assessment is necessary to insure
that the economic impact is not a limiting factor in
establishing effluent treatment technologies. Table 10
lists the nine commodities and the twenty-nine subcategories
in this report.
FACTORS CONSIDERED
Manufacturing Processes
Each commodity can be further subcategorized into three very
general classes - dry crushing and grinding, wet crushing
and grinding (shaping), and crushing and beneficiation
(including flotation, heavy media, et al). Each of these
processes is described in detail in Section V of this
report, including process flow diagrams pertinent to the
specific facilities using the process.
Raw Materials
The raw materials used are principally ores which vary
across this segment of the industry and also vary within a
given deposit. Despite these variations, differencies in
ore grades do not generally affect the ability to achieve
the effluent limitations. In cases where it does, different
processes are used and subcategorization is better applied
by process type as described in the above paragraph.
52
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Commodity
Dimension stone
Crushed stone
Construction
sand and gravel
TABLE 10
Industry Categorization
SIC Code Subcatecror^
1411
1422,1423,
1429,1499
14U2
Industrial sand 1446
Gypsum
1492
Asphaltic Minerals 1499
Asbestos and
Wollastonite
Lightweight
Aggregates
1499
1499
Mica and Sericite 1499
No further subcategorization
Dry
Wet
Flotation
Dry
Wet
Dredging, on-land
processing
Dry
Wet
Flotation (acid and alkali)
Flotation (HF)
Dry
Dry, wet scrubbers
HMS
Bituminoius lime-stone
Oil impregnated diatomite
Gilsonite
Asbestos, Dry
Asbestos, Wet
Wollastonite
Perlite
Pumice
Vermiculite
Dry
Wet
Wet Beneficiation
either no clay or
general purpose
clay by-product
Wet Beneficiation
cer.gr. by-product
53
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Product Purity
The mineral extraction processes covered in this report
yield products which vary in purity from what would be
considered a chemical technical grade to an essentially
analytical reagent quality. Product purity was not
considered to be a viable criterion for categorization of
the industry. Pure product manufacture usually generates
more waste than the production of lower grades of material,
and thus could be a basis for subcategorization. As is the
case for variation of ore grade discussed under raw
materials previously, pure products usually result from
different beneficiation processes, and subcategorization is
better applied there.
Facility Size
For this segment of the industry, information was obtained
from more than 400 different mineral mining sites. Capacity
varied from as little as 5 to 5,000 kkg/day. Setting
standards based on pounds pollutant per ton production
minimizes the differences in facility sizes. The economic
impact on facility size will be addressed in another study.
Facility Age
The newest facility studied was less than a year old and the
oldest was 150 years old. There is no correlation between
facility age and the ability to treat process waste water to
acceptable levels of pollutants. Also the equipment in the
oldest facilities either operates on the same principle or
is identical to equipment used in modern facilities.
Therefore, facility age was not an acceptable criterion for
categorization.
Facility Location
The locations of the more than 400 mineral mining and
processing sites studied are in 45 states spread from coast
to coast and north to south. Some facilities are located in
arid regions of the country, allowing the use of evaporation
ponds and surface disposal on the facility site. Other
facilities are located near raw material mineral deposits
which are highly localized in certain areas of the country.
In general the principal factor within facility location
affecting effluent quantity or quality is the amount of
precipitation and evaporation. Appropriate consideration of
these factors was taken where applicable, most notably mine
water discharge.
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SECTION V
WATER USE AND WASTE CHARACTERIZATION
INTRODUCTION
This section discusses the specific water uses in the
minerals for the construction industry segment of the
mineral mining and processing industry, and the amounts of
process waste materials contained in these waters. The
process wastes are characterized as raw waste loads
emanating from specific processes in the extraction of the
materials involved in this study and are given either in
terms of kg/kkg of product produced or ore processed. The
specific water uses and amounts are given in terms of 1/kkg
of product produced or ore mined (gal/ton) for each of the
facilities contacted in this study. The treatments used by
the mining and processing facilities studied are
specifically described and the amount and type of water
borne waste effluent after treatment is characterized.
The verification sampling data measured at specific
facilities for each subcategory is included in this report
where industry data and data from other sources is lacking.
SPECIFIC WATER USES
Waste water originates in the mineral mining and processing
industry from the following sources.
(1) Non-contact cooling water
(2) Process generated water - wash water
transport water
scrubber water
process and product consumed water
miscellaneous water
(3) Auxiliary processes water
(4) Storm and ground water - mine water
storm runoff
Non-contact cooling water is defined as that cooling water
which does not come into direct contact with any raw
material, intermediate product, by-product or product used
in or resulting from the process or any process water. Such
water will be regulated by general limitations applicable to
all industries.
55
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Process generated waste water is defined as that water
which, in the mineral processing operations such as
crushing, washing, and benefication, comes into direct
contact with any raw material, intermediate product,
by-product or product used in or resulting from the process.
Auxiliary processes water is defined as that used for
processes necessary for the manufacture of a product but not
contacting the process materials, for example influent water
treatment. Such water will be regulated by general
limitations applicable to all industries.
The quantity of water usage for facilities in the minerals
for the construction industry segment of the mineral mining
and processing industry ranges from 0 to 2,640,000 I/day (0
to 656,000 gal/day). In general, the facilities using very
large quantities of water use it for heavy media separation
and flotation processes and, in some cases, wet scrubbing
and non-contact cooling.
Non-Contact Cooling Water
The largest use of non-contact cooling water in this segment
of the mineral mining industry is for the cooling of
equipment, such as crusher bearings, dryers, pumps and air
compressors.
Contact Cooling Water
Insignificant quantities of contact cooling water is used in
this segment of the mineral mining industry. When used, it
usually either evaporates immediately or remains with the
product.
Wash Water
This water also comes under the heading of process water
because it comes into direct contact with either the raw
material, reactants or products. Examples of this type of
water usage are ore washing to remove fines and washing of
crushed stone, sand and gravel. Waste effluents can arise
from these washing sources, due to the fact that the
resultant solution or suspension may contain impurities or
may be too dilute a solution to reuse or recover.
Transport Water
Water is widely used in the mineral mining industry to
transport ore to and between various process steps. Water
is used to move crude ore from mine to facility, from
crushers to grinding mills and to transport tailings to
final retention ponds. Transport water is process water.
56
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Scrubber Water
Particularly in the dry processing of many of the minerals
in this industry, wet scrubbers are used for air pollution
control. These scrubbers are primarily used on dryers,
grinding mills, screens, conveyors and packaging equipment.
Scrubber water is process water.
Process and Product Consumed Water
Process water is primarily used in this industry during
blunging, pug processing, wet screening, log washing, heavy
media separation and flotation unit processes. The largest
volume of water is used in the latter four processes.
Product consumed water is often evaporated or shipped with
the product as a slurry or wet filter cake.
Miscellaneous Water
These water uses vary widely among the facilities with
general usage for floor washing and cleanup, safety showers
and eye wash stations and sanitary uses. The resultant
streams are either not contaminated or only slightly
contaminated with wastes. The general practice is to
discharge such streams without treatment or combine with
process water prior to treatment.
Another miscellaneous water use in this industry involves
the use of sprays to control dust at crushers, conveyor
transfer points, discharge chutes and stockpiles. This
water is usually low volume and is either evaporated or
adsorbed on the ore. The water uses so described are
process waters.
Auxiliary Processes Water.
Auxiliary processes water include blowdowns from cooling
towers, boilers and water treatment. The volume of water
used for these purposes in this industry is minimal.
However, when they are present, they usually are highly
concentrated in waste materials.
Storm and Ground Water
Water will enter the mine area from three natural sources,
direct . precipitation, storm runoff and ground water
intrusion. Water contacting the exposed ore or disturbed
overburden will be contaminated. Storm water and runoff can
also become contaminated at the processing site from storage
piles, process equipment and dusts that are emitted during
processing.
57
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PROCESS WASTE CHARACTERIZATION
The mineral products are discussed in Standard Industrial
Classification (SIC) Code numerical sequence in this
section. For each mineral product the following information
is given:
— a short description of the processes at the
facilities studied and pertinent flow diagrams;
— raw waste load data per unit weight of product
or raw material processed;
— water consumption data per unit weight of product
or raw material processed;
— specific facility waste effluents found and the
post-process treatments used to produce them.
DIMENSION STONE (SIC 1U11)
Sixteen dimension stone quarries and/or processing
facilities were inspected for the purpose of studying this
industry. These companies employ almost 3,200 persons and
process about 300,000 kkg/yr (330,000 tons/yr) of finished
dimension stone products. Production of quarry stone was
about 1,340,000 kkg (1,480,000 tons) in 1972.
Process Description
The quarrying of dimension stone can be accomplished using
six primary techniques. Some can be used singly, most are
used in various combinations. These techniques, their
principal combinations, and their areas of use, are
discussed as follows:
(1) Drilling, with or without broaching, dry or wet, simply
results in circular holes in the stone. On occasion,
shallow drilling of holes a few centimeters apart is the
prelude to insertion of explosive charges, or to
insertion of wedges, or wedges with two especially
shaped iron strips ("plugs-and-feathers"). On other
occasions, drilling of deeper holes, followed by removal
of stone between holes (broaching) is the primary means
of stone cutting. Drilling is either dry or wet with
water serving to suppress dust, to wash away stone chips
from the- working zone, and to keep the drills cool and
prolong the cutting edge. Drilling to some extent is
necessary in virtually all dimension stone quarrying.
58
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(2) Channel machines are simple, long, semi-automated,
multiple-head chisels. They are electrically or steam
powered (with the steam generating unit an integral part
of each machine), and are primarily used on limestone
along with other techniques. The machines are always
used with water, primarily to remove stone chips which
are formed by machine action.
(3) Wire sawing is another technique requiring the use of
water. Generally, a slurry of hard sand or silicon
carbide in water is used in connection with the saw.
The use of wire saws is probably not justified in small
quarries, as the initial setup is time consuming and
costly. However, the use of wire saws permits decreased
effort later at the saw facility, and will result in
decreased loss of stone. Wire saws are used chiefly on
granite and limestone.
(**) Low level explosives, particularly black powder, are
used in the quarrying of slate, marble, and mica schist.
(5) Jet piercing is used primarily with granite in the
dimension stone industry. This technique is based on
the use of high velocity jet flames to cut channels. It
involves combustion of oxygen and a fuel oil fed under
pressure through a nozzle to attain jet flames of over
2600°C (5000°F). A stream of water joins the flame and
the combined effect is spalling and disintegration of
the rock into fragments which are blown out of the
.immediate zone.
(6) Splitting techniques of one sort or another seem to be
used in the quarry on nearly all dimension stones.
Splitting always requires initial spaced drilling of
holes in the stone, usually along a straight line, and
following the "rift" of the stone if it is well defined.
Simple wedges, or "plugs-and-feathers" are inserted in
the holes and a workman then forces splitting by driving
in the wedges with a sledge hammer. This technique
appears crude, but with a skilled workman good cuts can
be made.
After a large block of stone is freed, it is either hoisted
on to a truck- which drives from the floor of the quarry to
the facility, or the block is removed from the quarry by
means of a derrick, and then loaded on a truck.
Most dimension stone processing facilities are located at or
close to the quarry. On occasion, centrally located
facilities serve two or more quarries (as facilities 3029,
3038, 3053, 3007, 3051). To a much lesser extent, one
quarry can serve two or more processors (as at facilities
59
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3304 and 3305). Also in a well defined, specialized
producing area such as Barre, Vermont, two large quarriers,
who are also stone processors, sell blocks and/or slabs to
approximately 50 processors. However, the most common
situation is that in which the processor has his own quarry.
In this study, no situation was seen in which a quarry was
operated without an accompanying processing facility.
In dimension stone processing, the first step is to saw the
blocks into slabs. The initial sawing is accomplished using
gang saws (large hack saws), wire saws, or occasionally,
rotating diamond saws. All saw systems use considerable
water, for cooling and particle removal, but this water is
usually recycled. Generally, the saw facility is operated
at the same physical location as the finishing facility, and
without any conscious demarkation or separation, but in a
few cases the saw facility is either at a separate location
(facilities 3034 and 3051), is not associated with any
finishing operations (facilities 3008, 3010 and 5600), or is
separately housed and operated but at the same location
(facilities 3007 and 3001).
After the initial sawing of blocks to slabs of predetermined
thickeness, finishing operations are initiated. The
finishing operations used on the stone are varied and are a
function of the properties of the stone itself, or are
equally affected by characteristics of the end product. For
example, after sawing, slate is hand split without further
processing if used for structural stone, but is hand split,
trimmed, and punched if processed to shingles, and it is
hand split and trimmed if processed to flagstone. Slate is
rarely polished, as the rough effect of hand splitting is
desirable. Mica schist and sandstone are generally only
sawed, since they are used primarily for external structural
stone. Limestone cannot be polished, but it can be shaped,
sculptured and machined for a variety of functional and/or
primarily decorative purposes. Granite and marble are also
multi-purposed stones and can take a high polish. Thus
polishing equipment and supplies, and water usage, are
important considerations for these two large categories of
stone. Dolomitic limestone can be polished, but not to the
same degree as granite or marble. Generally most of this
stone is used primarily for internal or external structural
pieces, veneer, sill stone, and rubble stone. ,A schematic
flow sheet for dimension stone quarrying and processing is
given in Figure 11.
Raw Waste Loads
Extremely large quantities of stone are quarried in the
dimension stone industry, and yields of good quality stone
are quite low and variable, from 15 percent to 65 percent.
60
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OY
-*-»
_WATE_R_ __
(OPTIONAL )~~|
QUARRY
1
MAKE-UP
WATER
RECYCLE
•gjj
SAW PLANT
POND OR
ABANDONED
QUARRY
MAKE-UP
WATER
RECYCLE
FINISHING
PLANT
SETTLING
PONDS
•a* PRODUCT
FIGURE n
DIMENSION STONE MINING AND PROCESSING
-------
with 0.5 to 5.7 kkg of waste stone per kkg of product. The
lowest yields are characteristic of the stones which are
generally highly polished and therefore require the most
perfection (granite and marble). Low yields (18 percent)
also occur in slate due to large quantities of extraneous
rock. Most of the yield losses occur at the quarry but some
unavoidable yield losses also occur in the saw facilities
and finishing facilities. The table below lists some
dimension stone quarry and facility yields.
Stone Type
Slate
Dolomitic
limestone
Limestone
Marble
Granite
Facility
3053
3040
3010
3007
3051
3001
3038
Yield
18%
Loss
kkg/kkg
Product
4.56
65%
35%
50%
25%
15%
15-40%*
0.54
1.86
1.00
3.00
5,67
5.67-1.50
* Many quarries of differing stones and locations.
Untreated aqueous effluents can occur in the quarry and at
the saw and finishing facilities.
Some quarries use no water; mica schist, dolomitic
limestone, slate and sandstone, (facilities 5600, 3017,
3018, 3053. . 3039, 3040), plus some marble, travertine
marble, and granite (facilities 3051, 3034, 3001, 3029).
Ground or rain waters do accumulate in these quarries but
rarely cause severe problems. Most limestone and some
granite quarries do use water for sawing or channel cutting,
(facilities 3038, 3304, 3305, 3306, 3007, 3008, 3009, 3010)
therefore, ground and rain water is retained, and other
sources of water may also be tapped for makeup. This water
is continuously recycled into the quarry sump and is rarely
discharged.
All saw facilities use water and the general practice is to
recycle after settling most of the suspended solids. The
quality of untreated effluent from saw facilities can be
significant. However, no data is available of the raw waste
load (dissolved and suspended solids) of these effluents.
The same situation is true of untreated effluents from
finishing facilities. In many cases, the saw facilities and
the finishing facilities are under the same roof, in which
case the water effluents are combined.
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Water Use
In the quarrying of dimension stone, water is used- in
quantity wherever two specific quarrying methods are used,
The methods are wire sawing and channel machining
(facility-quarries 3038, 3007, 3008, 3009, 3010, 3304, 3305,
3306). In all cases, rain and ground " water are used,
without pretreatment, as well as water from any other
convenient source (creek, city water, abandoned quarry,
etc.). In no case has the quantity of water used been
determined. Water is also used in wet drilling, but this
quantity is small and not measured.
In the saw and finishing facilities, water is used with the
gang saws, wire saws, diamond saws, polishing mills,
grinders, and in final washing. The greatest quantity of
water is used in sawing, whether it is for initial sawing in
the saw facility or in connection with operations in the
finishing facility.
In Table 11, water and effluent data are presented for
dimension stone facilities having reliable data available.
Combined saw facility and finishing facility raw water
effluents vary from 4,340 to 43,400 1/kkg of product (1,040
to 10,400 gal/ton). Water usage varies due to varying stone
processes, water availability, and facility attitudes on
water usage.
The quality of water used in dimension stone processing
appears to be of little concerni For the most part, river,
creek, well, abandoned quarry, or lake water is used without
prior treatment. Occasionally pretreatment in the form of
prior elementary screening or filtration is performed
(facilities 3018, 3051), and in only two instances is city
water used (facility 3007, 3029) as part of the makeup
water.
Waste Water Treatment
In an industry where process feed water is largely obtained
from any convenient source, and used with virtually no
pretreatment, it would be unexpected to find a high degree
of sophistication in the treatment of waste water. Such is
the case in most of the dimension stone industry.
In no known case is quarry water given any treatment prior
to its discharge to a convenient stream, field, abandoned
quarry or settling pond. This type of pumpout is quite
infrequent, the water contains only small quantities of
suspended solids (usually <25 mg/1) and no known toxic
pollutants.
63
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TABLE 11
Dimension Stone Water Use
Makeup Water
Stone and
Plant
Mica Schist
5600
Slate
3053
Dolomitic
Limestone
3039
3040
Limestone
3007
3009
3010*
Granite
3001
3029
3038
Marble
3051
3304
3305
3306
1/kkg of
stone processed
(gal/ton)
20 (5)
450 (110)
1,250 (300)
13,000 (3100)
540 (130)
unknown
unknown
unknown
840 (200)
1,600 (390)
100,000 (24,000)
590 (140)
unknown
1,300 (300)
Water Use,
processed
Saw Plant
4,460
unknown
unknown
unknown
16,600
unknown
9,800
7,350
unknown
unknown
100,000
unknown
unknown
unknown
1/kkg of stone
(gal/1000 Ib)
Finish Plant
none
unknown
unknown
unknown
1,600
unknown
7,360
unknown
unknown
unknown
unknown
unknown
unknown
Combined
4,460
4,550
unknown
13,000
18,200
6,030
9,800
14,700
3,900
43,400
unknown
5,940
39,800**
6,500
* No finishing plant
** Primarily a saw plant which ships slabs to 3304 for finishing.
-------
In dimension stone processing facilities, water is generally
used with no recycle or with 70-100 percent recycle.
Facility effluents may be discharged with no treatment
whatsoever (facilities 3018, 3051), discharged after
settling in ponds or quarries (facilities 5600, 3053, 3039,
3040, 3007, 3008, 3009, 3001, 3029, 3034, 3304, 3305),
discharged or recycled after chemical treatment and settling
(facilities 3038, 3306), or there may be no effluent
whatsoever (facilities 3017, 3010) due to 100 percent
recycle. This data is summarized in the following table.
Stone
Mica Schist
Slate
Dolomitic
Limestone
Limestone
Granite
Marble
5600
3017
3018
3053
3039
3040
3007
3008
3009
3010
3001
3029
3038
3002
3003
3034
3051
3304
3305
3306
Waste Water Trea-tment
settling
100* recycle
none
settling
settling
settling
settling
settling, 10056 recycle
settling
settling, 10055 recycle
settling
settling
flocculants, settling,
100X recycle
settling
settling
settling
none
settling
settling
settling, polymer, alum
At facility 3038 there is chemical treatment of facility
waste effluents, solids separation via a raked tank with
filtration of tank underflow, plus total recycle of tank
overflow. This practice is necessary since the facility
hydraulic load would otherwise overwhelm the small adjacent
river. Furthermore, the facility has a proprietary process
for separating silicon carbide particles from other solids
in order to resell this valuable by-product. Since granite
facilities are the only users of silicon carbide,
non-granite processors could not obtain any cost benefits
from this practice.
Effluents and Disposal
Disposition of quarry and facility waste stone is more a
function of state requirements than of any other factor.
Thus, waste stone and settling pond solids are
65
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conscientiously used to refill and reclaim quarries where
the state has strict reclamation laws. Corporate policy
regarding disposition of solid wastes is the second most
important factor, and type and yield of stone is the least
important factor. Thus, where both state and corporate
policy are lenient, solid wastes are accumulated in large
piles near the quarry (facilities 3017, 3053, and to some
extent 3051) .
In addition to refilling abandoned quarries, some facilities
make real efforts to convert waste stone to usable rubble
stone (facilities 3034, 3040), crushed stone (facilities
3051, 3038, 3018), or sell as rip rap (facilities 3051,
3039). Successful efforts to convert low grade stone to low
priced products are seen only in the marble, granite, and
dolomitic limestone industries. The only estimate that can
be made of solid wastes, regardless of disposition, is that
which is based on data in the last column of a preceding
table of stone losses, which shows the loss of dimension
stone as kg/kkg product.
On the average, dimension stone facilities are much more
careful in their handling of water effluents than they are
for solid wastes. The most important factors are state and
federal agencies which impose or are likely to impose strict
regulations. The single important water effluent parameter
for this industry is suspended solids.
Some quarries use no water (generally mica schist, dolomitic
limestone, slate, sandstone). Water use is associated with
channel machines and wire saws (mining methods), and thus it
is seen in limestone quarrying (facilities 3007, 3008, 3009
and 3010), and to some extent in granite (facility 3038),
and marble (facilities 3304, 3305, 3306).
Where water is used in quarrying, there is 100 percent
recycle. Pit pumpout does occur as a seasonal factor at
some locations, but suspended solids have generally been
found to be less than 25 mg/1. If there is a problem or a
border-line situation with respect to suspended solids, it
can be attributed more to stone type than to any other
factor. For example, granite quarry pumpout at facility
3001 is 25 mg/1 TSS. However, limestone, marble, and
dolomitic limestone quarry water is generally very clear and
much lower in suspended solids.
At no facility where wet quarrying methods are used is the
water flow measured. Likewise, pit pumpout which is
generally infrequent, is rarely measured. A few existing
state permits for pit pumpout are specified in terms of
total pumpout for given periods of time, as well as
66
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allowable levels of pollutants (primarily suspended solids,
pH, and turbidity).
Very little quantitative data is available on the quality or
quantity of dimension stone processing facility treated
effluents. The common method of treatment simply involves
the use of settling ponds. In some cases, the settling
ponds lose so much water by seepage that there is no
overflow. In other cases, the settling pond effluent flow
rate does not match the raw waste flow rate due to increases
in volume from rainfall and runoff and decreases from
seepage, evaporation, and undetermined degrees of water
recycle to the processing facilities.
Several analyses of treated effluents available are as
follows:
Facility 3007
Facility 3304
Facility 3305
Facility 3306
Facility 3002
Facility 3003
Facility 3001
Facility 5600
Facility 3051
7.8 pH
7.1 mg/1 TSS (range 0-24.5)
<10 JTU
<100 mg/1 total solids
<5 mg/1 TSS
<1 BOD
<1 JTU
600 mg/1 TSS
34 mg/1 TSS
Water including runoff from 2
quarries
1 mg/1 TSS
4 mg/1 TSS
Finishing Facility 37 mg/1 TSS
Quarry - 7 mg/1 TSS
Quarry - 7 mg/1 TSS
Facility 1658 mg/1 TSS
Second Facility 4008 mg/1 TSS
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CRUSHED STONE (SIC 1422, 1423, 1429)
There are more than 4,600 quarries producing crushed stone
in the United States, in every state except Delaware. The
types of stone mined and crushed include: limestone and
dolomite (73 percent of the total tonnage); granite; trap
rock; marble; shell; calcareous marl; sandstone, quartz, and
quartzite; slate; and other stone. Pennsylvania leads the
nation in yearly output which combined with the outputs of
Florida, Illinois, Ohio, and Texas account for approximately
one-third of the total U.S. production.
Facilities smaller than 22,700 kkg/yr (25,000 tons/yr)
account for less than 2 percent of the total production.
The principal use for crushed stone of all kinds is as an
aggregate in the construction and paving industries. The
crushed stone industry is the largest non-fuel, non-metallic
mineral industry in the United States from the standpoint of
total value of production and is second only to sand and
gravel in volume production.
Three basic methods of extraction are practiced: (1)removal
of raw material from an open face quarry; (2)removal of raw
material from an underground mine (approximately 5 percent
of total crushed stone production); and (3) shell dredging,
mainly from coastal waterways (approximately 1 percent of
total crushed stone production). Once the raw material is
extracted, methods of processing are similar, consisting of
crushing, screening, washing, sizing, and stockpiling.
Approximately 0.2 percent of total crushed stone production
employ flotation techniques to obtain a calcite (CaC03)
product.
Based on 189 facility contacts (approximately 4 percent of
the total facilities), the industry was divided into the
following subcategories:
(1) Dry process (52 facilities contacted)
(2) Wet process (130 facilities contacted)
(3) Flotation process (3 facilities contacted)
(4) shell dredging (4 facilities contacted)
These facilities are located in 38 states in all areas of
the nation representing various levels of yearly production
and facility age. Production figures range from 36,000
1,180,000 kkg/yr (40,000-1,300,000 tons/yr) and facility
ages vary from less than one year to over 150 years old.
68
-------
DRY PROCESS
Process Description
Most crushed stone is mined from quarries. After removal of
the overburden, drilling and blasting techniques are
employed to loosen the raw material. The resulting quarry
is characterized by steep, almost vertical walls, and may be
several hundred meters deep. Excavation is normally done on
a number of horizontal levels, termed benches, located at
various depths. In most cases, front-end loaders and/or
power shovels are utilized to load the raw material into
trucks which in turn -transport it to the processing
facility. In some cases, however, the raw material is moved
to the facility by a belt conveyor system perhaps preceded
by a primary crusher. Another variation is the use of
portable processing facilities .which can be situated near
the blasting site, on one of the quarry benches or on the
floor of the quarry. In this situation, the finished
product is trucked from the quarry to the stockpile area.
Specific methods vary with the nature and location of the
deposit.
No distinction is made between permanent facilities and
portable facilities since the individual operations therein
are basically identical. At the processing facility, the
raw material passes through screening and crushing
operations prior to the final sizing and stockpiling.
Customer demands for various product grades determines the
number and -position of the screens and crushers. Figure 12
is a dry process flow diagram.
Raw Wastes
The raw wastes from the process consist of oversized or
undersized crushed stone and is usually disposed of in pits.
The amounts of these solid wastes are variable, depending on
the specific grades of material being processed. It is
difficult to determine an average value of raw waste per
metric ton of product processed, since the industry does not
produce a great deal of solid waste.
Water Use
No process water is used in the crushing and screening of
dry process crushed stone. Many operators dewater their
quarries because of ground water, rain, or surface runoff.
Approximately half of the quarries studied dewater their
quarries either on an intermittent or continual basis.
69
-------
QUARRY
VIBRATOR
FEEDER
PRIMARY
CRUSHER
CRUSH
PIT PUMPOUT
SCREEN
PRODUCT
FIGURE 12
CRUSHED STONE MINING AND PROCESSING
(DRY)
-------
Incidental water uses include non-contact cooling water for
cooling crusher bearings and water used for dust
suppression, which is adsorbed onto the product and does not
result in a discharge.
Incidental Water Use
1/fckS Qf product (gal/ton)
Faci lity Non~contact cooling Dust suppression
UO (9.5) None
1216 38 (9.2) 81 (20)
5660 None 6.0 (1.5)
Waste Water Treatment
Pit pumpout and non- contact cooling water are usually
discharged without treatment. Some facilities, such as
1020, pump their quarry water through settling ponds prior
to discharge. Other facilities such as 1216 and 1022 are
able to recycle about one half of their non-contact cooling
water.
Effluent and Disposal
Facilities in this subcategory are characterized by a
waterborne effluent in the form of pit pumpout and some
discharge non-contact cooling water.
CRUSHED STONE, WET PROCESS
Process Description
Excavation and transportation of crushed stone for wet
processing use methods identical to those for dry
processing. Wet processing is the same as dry processing
with the exception that water is added to the system for
washing the stone. This is normally done by adding spray
bars to the final screening operation after crushing.
Figure 13 is a process flow diagram for wet processing
crushed stone. In many cases, not all of the product is
washed, and a separate washing facility or tower is
incorporated which receives all of the material to be
washed. This separate system will normally only include a
set of screens for sizing which are equipped with spray
bars. In the portable processing facility, a portable wash
facility can also be incorporated to satisfy the demands for
a washed material. At facility 5662, the finished product
from the dry facility is fed into a separate unit consisting
of a logwasher and screens equipped with spray bars.
71
-------
QUARRY
CRUSH
SCREEN
WATER
SCREEN
AND
WASH
PRODUCT
-•4
to
PIT
PUMPOUT
SETTLING AIDS B»»
DEWATER
POND
WASTE
EFFLUENT RECYCLE
FIGURE 13
CRUSHED STONE MINING AND PROCESSING
(WET)
-------
Raw Waste Loads
The raw waste loads of wet processing facilities are similar
to those from dry processing facilities. The quantity of
raw waste varies as shown by the tabulation as follows:
Facility Raw Waste Load,
kg/kkq of product (lb/1000 _lbX
1001 40
1002 50
1003 40
1004 150
1021 80
1023 20
1039 20
1212 270
1213 30
1215 10
1221 130
1974 22
5640. 10
5664 180
Water Use
Incidental water is also used for non-contact cooling and/or
dust suppression. Use varies widely as shown below:
Water Use
(gal/1000 Ib)
Facility Non-contact Cooling Dust
1001 None None
1002 None None
1003 None None
1004 None None
1021 None 500
1022 8 None
1023 Unknown 16
1 039 None Unknown
1040 None 13
1212 None None
1213 None None
1215 290 8
1221 None None
1974 17 60
5640 None None
There is no distinction between wet and dry process pit
pumpout. Neither frequency of flow nor pumping methods
differ for a wet or dry process.
73
-------
Water necessary for the washing operations is drawn from any
one or combination of the following sources: quarries,
wells, rivers, company owned ponds, and settling ponds.
There is no set quantity of water necessary for washing
crushed stone as the amount required is dependent upon the
deposit from which the raw material is extracted. A deposit
associated with a higher percentage of fine material will
require a larger volume of water to remove impurities than
one with a lower percentage of fines. A second factor
affecting the amount of washwater is the degree of crushing
involved. The amount of undesirable fines increases with
the number of crushing operations, and consequently the
greater the volume of water necessary to wash the finer
grades of material.
Washwater
Percent of 1/kkg of
Facility washed material product (gal/ton)
5663 8
5640 15
1439 40
1219 50
1004 100
1003 100
Less than 10 percent of all crushed limestone operators dry
their product or a portion of their product. Approximately
5 percent of these operators employ a wet scrubber in
conjunction with the dryer as a means of air pollution
control. Facility 1217 uses a rotary dryer approximately
30-40 percent of the total production time. At such time,
the wet scrubber associated with this dryer utilizes water
at the rate of 2,600 1/kkg of dried product (690 gal/ton).
Waste Water Treatment
Non-contact cooling water is generally discharged without
treatment as is the case with facility 1974. Pit pumpout
may either be discharged directly with no treatment
(facility 1039)» discharged following treatment (facility
5640), or discharged with the treated effluent from the
washing operation (facility 1001). In the latter case, the
quarry water may be combined with the untreated facility
effluent and then flow through a settling pond system prior
to discharge (facility 5662). The quarry water may instead
join the semi-treated effluent as flow to the second of two
settling ponds (facility 1213). There are many variations
to the handling of pit pumpout by the wet processor. In
general, however, the pit water is pumped through a settling
pond system.
74
-------
In all of the facilities contacted, the effluent from the
washing operation is sent through a settling pond system
prior to discharge. This system generally consists of at
least two settling ponds in series designed to reduce the
suspended solids in the final di scharge. Facility 1439
utilizes two settling ponds to treat the washwater. The
suspended solids concentration entering the first settling
pond is 7000-8000 mg/1 which is reduced to a level of 15-20
mg/1 after flowing through the two ponds. Facility 3027
reports its settling pond system reduces the total suspended
solid level in the facility washwater by 95 percent.
In some instances, flocculating agents are added to the
waste stream from the wash facility prior to entering the
first settling pond to expedite the settling of the fine
particles. Facility 1222 uses such an agent. Mechanical
equipment may be used in conjunction with a settling pond
system in an effort to reduce the amount of solids entering
the first pond. At facility 1040, the waste water from the
washing operation flows through a dewatering screw which
reportedly removes 50 percent of the solid material which
represents a salvageable product. The waste water flows
from the screw into the first settling pond.
Facility 1039 has an even more effective method for treating
waste water from the washing operation. As with facility
1040r the waste water flows into a dewatering screw. Just
prior to this step, however, facility 1039 employs a polymer
injection system which releases a flocculating agent into
the waste water. This enhances the action of the screw and
leads to a higher salvage rate.
Effluents and Disposal
Waterborne waste discharges from facilities of this
subcategory can consist of pit pumpout, non-contact cooling
water, or process wash water plus pit pumpout. Where wash
water is not discharged, it is completely recycled to the
process. Of the facilities contacted that wash crushed
stone, 33 percent do not discharge their wash water. Many
of the remaining facilities recycle a portion of their waste
water after treatment. It should be noted that evaporation
and percolation have a tendency to reduce the flow rate of
the final discharge in many instances. The main concern
with the final effluent of a wet crushed stone operation is
the level of suspended solids. This may vary greatly
depending on the deposit, the degree of crushing, and the
treatment methods employed.
The waste water from the wet scrubber in facility 1217 is
sent to the first of two settling ponds in series. After
flowing through both ponds, the water is recycled back to
75
-------
•the scrubber with no discharge. Effluent data from some of
the facilities that do discharge wash water after treatment
by settling ponds are:
facility effluent
1004 Flow - 8.7 x 10*
I/day (2.30 mgd)
pH - 7.5
Turbidity - 16 FTU
1053 Flow - 1.8 x 10*
I/day (0,48 mgd)
pH - 8. 4
Turbidity - 18 FTU
1218 Flow - 6.2 x 10*
I/day (1.64 mgd)
TSS - 20 mg/1
source
treated discharge composed
of wash water (456) and
pit pumpout (96%)
wash water after treatment
wash water after treat-
ment then combined with
pit pumpout
Of the facilities contacted the following are achieving
total recycle of process generated waste water:
1002
1062
1066
1070
1161
1439
1003
1063
1067
1071
1212
3027
1039
1064
0168
1072
1220
5663
1040
1065
1079
1090
1223
The following facilities use a common pond for process waste
water and mine water. These facilities use much of this
combined pond water for the total process water intake:
facility
1001
1023
1219
1222
1226
1227
1228
5662
5664
effluent
TSS mg/1
8
34
2
9
40, 42
Many treatment ponds discharge less than the influent
because of ground seepage. Facility 1974 is an example of a
facility achieving no discharge because of seepage. Mine
water discharge data from several facilities of this
subcategory are;
76
-------
facility TSS mq/1
1001 3
1003 7
1004 12
1020 (1)5, (2)1
1021 14
1022 15
1023 34
1039 7
1040 25
1214 <1,2,3
1215 (1)^2, (2)28
1219 2
1224 10-30
5660 14
5661 0
5663 1
5664 42.4
(1) first pit
(2) second pit
These discharges typically are not treated after removal
from the pit sump.
Many of the operators in this subcategory must periodically
clean their settling ponds of the fines which have settled
out from wash water. A clamshell bucket is often used to
accomplish this task. The fines recovered are sometimes in
the form of a saleable product (facility 1215) while in most
instances these fines are actually a waste material. In
this instance, the material is either stockpiled or used as
landfill (facilities 1053 and 1212). The quantity of waste
materials entering the pond varies for each operator and the
processes involved. Facility 1002 reports that the
washwater entering the settling ponds is composed of 4-5
percent waste fines. The frequency of pond cleaning depends
not only on the processes involved but also on the size of
the pond. Facility 1217 must clean its settling ponds once
per month, the recovered material serving as landfill. The
disposal of these fines presents problems for many
operators.
77
-------
CRUSHED STONE, FLOTATION PROCESS
Process Description
Marble or other carbonaceous rock can be transported from
the quarry to the processing facility where it is crushed,
screened or wet milled and fed to flotation cells.
Impurities are removed in the overflow and the pumped
product is collected from the underflow, it is further wet
milled to achieve a more uniform particle size, dried, and
shipped. A process diagram is shown in Figure 1U.
Raw Waste Load
Process raw wastes consist of clays and fines separated
during the initial washing operations and iron minerals,
silicates, mica, and graphite separated by flotation.
kq/kkg of product (Ib /1QOO Ib)
waste 1975 3069
clays and 1,000 unknown
fines
flotation 50-100 50-100
wastes
(solids)
In addition to the above, the flotation reagents added
(organic amines, fatty acids and pine oils) are also was-ted.
The quantities of these materials are estimated to range
from 0.1 to 1.0 kg/kkg of material.
Water Use
The water use for the three facilities is outlined as
follows. There are considerable variations in process and
mine pumpout waters.
78
-------
CONDITIONERS
PIT PUMPOUT
WATER
CRUSHING
SCREENING
OR
WET
GRINDING
WASTE WATER
TO WASTE
TREATMENT
WASTE WATER
DTKERS
WATER
V f 1
WATER VENT
' I T
FLOTATION
WET
MILLING
DRYING
PRODUCT
FIGURE 14
CRUSHED STONE MINING AND PROCESSING
(FLOTATION PROCESS)
-------
process
cooling
dust control
boiler
mine
pumpout
1975
151,000
(36,000)
22,700
(5,400)
1,510
(360)
unknown
1/kkg of product (gal/ton)
3069
4,900
(1,170)
850
(200)
1,400
(335)
6,600
(1,580)
none
1021
2,570
(610)
16,000
(3,800)
*Facility 1975 also employs some of this "process" water to
wash other materials.
Treatment
At facility 1975, all waste water is combined and fed to a
series of settling lagoons to remove suspended materials.
The water is then recycled back to other washing operations
with the exception of about 5 percent which is lost by
percolation and evaporation from the ponds. This loss is
made up by the addition of fresh water.
At facility 1429 a considerable portion of the waste water
is also recycled. The individual waste streams are sent to
settling tanks for removal of suspended solids. From these,
about 70 percent of the process water and all of the cooling
and boiler water is recycled. The remainder is released to
settling ponds for further removal of suspended solids prior
to discharge.
At facility 1021, lagooning is also used for removal of
suspended solids. Only at this facility is all water
discharged.
Effluent
At facility 1975, there is no effluent. Ninety-five percent
of the water is recycled and the remainder is lost by either
evaporation or percolation in the ponds.
For facilities 3069 and 1021 the effluents are listed as
follows along with corresponding intake water compositions.
In the case of facility 1021 the data presented are
analytical measurements made by the contractor.
80
-------
intake
water
(3069)
TSS 5
(mg/1)
BOD 1.0
(mg/1)
COD 1.0
(mg/1)
sulfate 3.5
(mg/1)
turbi- 10
dity (FTU)
chloride 3.8
(mg/1)
effluent
(1069)
10
intake mine
water ef fluent pumpout
Q021) (!02_1) (1021)
8
<2.Q
13
19
27
total
solids
(mg/1)
32
4.1
128
50
464
SHELL DREDGING
20
154
12
118
Process Description
Shell dredging is the hydraulic mining of semi-fossil oyster
and clam shells which are buried in alluvial estuarine
sediments. Extraction is carried out using self-contained
floating hydraulic suction dredges which operate in open
bays and sounds, usually several miles from shore. This
activity is conducted along the coastal Gulf of Mexico and
to a lesser extent along the Atlantic coast. Shell dredges
are self-contained and support an average crew of 12 men
working 12 hours/day in two shifts.
All processing is done on board the dredge and consists of
washing and screening the shells before loading them on
tow-barges for transport to shore. Shell is a major source
of calcium carbonate along the Gulf Coast States and is used
for construction aggregate and Portland cement
manufacturing. Shell dredging and on-board processing is
regulated under section 404 of the Act, Permits for Dredged
or Fill Material.
81
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CONSTRUCTION SAND AND GRAVEL (SIC 1442)
There are over 5,000 commercial operations, located in every
state of the nation, extracting and processing construction
sand and gravel. Three basic methods of sand and gravel
extraction are practiced: (1)dry pit, removal above the
water table; (2)wet pit, raw material extracted by means of
a dragline or barge-mounted dredging equipment both above
and below the water table; and (3)dredging, where sand and
gravel is recovered from public waterways, including lakes,
rivers, and estuaries. Once the raw material is extracted,
methods of processing are similar for all cases, typically
consisting of sand and gravel separation, screening,
crushing, sizing, and stockpiling.
Based on one hundred facility visits and contacts (2 percent
of the total), the industry was divided into the following
subcategories:
(1) Dry process (10 facilities contacted)
(2) Wet process (80 facilities contacted)
(3) Dredging with on-land processing
(7 facilities contacted)
These facilities are located in 22 states in all regions of
the nation representing production levels from 10,800 kkg/yr
(12,000 tons/yr) to over 1,800,000 kkg/yr (2,000,000
tons/yr). Facility ages varied from less than a year old to
more than 50 years old.
SAND AND GRAVEL, DRY PROCESS
Process Description
After removal of the overburden, the raw material is
extracted via front-end loader, power shovel or scraper and
conveyed to the processing unit with conveyor belts or
trucks. Specific methods vary with the nature and location
of the deposit. At the processing facility, the sand is
separated from the gravel via inclined vibrating screens and
sized according to percent passing various screen openings.
The larger sizes are used as a product or crushed and re-
sized. The degree of crushing and sizing is highly
dependent on the needs of the user. A typical process
diagram is shown in Figure 15.
Raw Waste Loads
The raw wastes consist of oversize or undersize sand and
gravel that is normally disposed of in worked-out pits. The
amounts of these solid wastes are quite variable, depending
82
-------
MINI
SEPARATION
SIZE
SAND
PRODUCT
WASTE FINES
oo
OJ
SIZE
WASTE FINES
GRAVEL
PRODUCT
CRUSH
FIGURE " 15
SAND AND GRAVEL MINING AND PROCESSING
-------
on the quality of the deposits being processed. Some dry
processing facilities are able to sell or utilize as much as
95 percent of the raw material, while others are able to
sell less than 50 percent. The remainder is stockpiled or
discarded as solid waste. The range of raw waste loads is
from 50 to over 500 kg/kkg of raw material, or, in different
terms, from 53 to over 1,000 kg/kkg of product.
Water Use
No water is used in the dry processing of sand and gravel.
Mine pumpout may occur during periods of rainfall or, in the
cases of portable or intermittent operations, prior to
initial start-up. Most pumpouts occur when the water level
reaches a predetermined height in a pit or low-area sump.
Incidental water uses may include non-contact cooling water
for crusher bearings and water for dust suppression. The
following tabulates incidental water use at selected
facilities:
1/kkg of product (gal/ton)
Facility Non-contact cooling Dust Suppression
1236 None 27,5 (6.6)
1231 None 16 (3.8)
1044 5 (1.2) 19 (4.5)
Waste Water Treatment
Mine pumpout and non-contact cooling water are typically
discharged without treatment. Dust suppression water is
adsorbed on the product and evaporated.
Effluents and Disposal
Facilities in this subcategory have no process water to
discharge. Where effluents occur, they consist of pit
pumpout and/or non-contact cooling water. At Facility 1044,
only non-contact cooling water is discharged. Facility 1007
discharges pit water on a regular basis without any
treatment. The pH of facility 1007 effluent ranges from
6.0-8.0, and the significant parameters are:
Flow, 1/kkg of product (gal/ton) 625 (150)
TSS, mg/1 55
TSS, kg/kkg of product (Ib/ton) 0.034 (0.068)
84
-------
.SAND AND GRAVEL, WET PROCESS
Process Description
Sand and gravel operations requiring extraction from a wet
pit or quarry typically use a dragline or a hydraulic dredge
to excavate the material. The hydraulic dredge conveys the
raw material as a wet slurry to the processing facility.
After removal of the overburden, the raw material from a dry
pit or quarry is extracted via front-end loader, power
shovel or scraper, and conveyed to the processing facility
on conveyor belts or in haul trucks.
Water in this subcategory is used to remove (wash) the clay
or other impurities from the sand and gravel. State, local,
and Federal specifications for construction aggregates
require the removal of clay fines and other impurities. The
sand and gravel deposits surveyed during this study ranged
from 5 to 30 percent clay content.
Facility processing includes washing, screening, and
otherwise classifying to size, crushing of oversize, and the
removal of impurities. Impurities which are soluble or
suspendable in water (e.g., clays) generally are washed out
satisfactorily. These facilities are a combination of
conveyors, screens, crushers, washing and classifying
equipment, and storage and loading facilities. A typical
wet processing facility would consist of the following
elements;
(1) A hopper, or equivalent, receives material transported
from the deposit. Generally, this hopper will be covered
with a "grizzly" of parallel bars to screen out rocks too
large to be handled by the facility.
(2) A scalping screen separates oversize material from the
smaller marketable sizes.
(3) The material passing through the scalping screen is fed
to a battery of screens, either vibrating or revolving, the
number, size, and arrangement of which will depend on the
number of sizes to be made. Water from sprays is applied
throughout the screening operation.
(4) From these screens the different sizes of gravel are
discharged into bins or onto conveyors for transportation to
stockpiles, or in some cases, to crushers and other screens
for further processing. The sand fraction passes to
classifying and dewatering equipment and from there to bins
and stockpiles. Screens are used to separate the sand from
the gravel and to make required separation coarser than a
-20 mesh sieve. Finer sizes of sand are produced by
85
-------
classification equipment. Figure 16 illustrates a
generalized flow diagram for a wet processing sand and
gravel facility.
A small number of facilities must remove deleterious
particles occurring in the deposit prior to washing and
screening. Particles considered undesirable are classified
as: soft fragments; thin and friable particles; shale;
argillaceous sandstones and limestones; porous and unsound
cherts; coated particles; coal; lignite and other low
density impurities. Heavy-media separation (i.e.,
sink-float) is used for the separation of materials based on
differing specific gravities. The process consists of
floating out the lightweight material on a heavy "liquid"
which is formed by suspension of finely ground heavy
ferromagnetic materials such as magnetite and/or
ferrosilicon in water. The "floated" impurities and the
"sink" product (sand and gravel) are passed over a screen
where the magnetite and/or ferrosilicon are removed by
magnetic separation and recycled. The impurities are
usually disposed of in nearby pits while the product is
transported to the facility for routine washing and sizing.
Figure 17 shows the heavy-media separation step used prior
to the processing illustrated in Figure 16.
Raw Waste Loads
Raw wastes consist of waste fines composed of clays, fine
mesh sands (usually less than 150 mesh), and other
impurities. Oversize material is crushed to size and
processed except in a few cases except where discarded. The
amounts of these wastes are variable, depending on the
nature of the raw material (i.e., percent of clay content)
and degree of processing at the facility. Facility 1981,
using heavy-media separation prior to wet processing, floats
out 150 kg/kkg of the total raw material fed to the
facility. The following lists the rate of raw waste
generation at several other facilities:
Facility kq/kkg of raw_material (lb/1000 Ib)
1006 140
1007 480
1055 50
1056 250
1391 80
3091 110
86
-------
CRUSH
CO
QUARRY
LEGEND;
ALTERNATE
ROUTES
WATER
SCREEN
y
>
SEF
-»
IA
\fv
ft
1
3H — *
JD WATER
RATE —. 1
^. WET ^ ^M.,*^^«
fca^sa HHiiiB»cac OFWA i F- R
CLASSIFICATION utwMitrt
' f f
PONDS AND/OR THICKENERS
EFFLUENT
WATER
RECYCLE
FIGURE 16
SAND AND GRAVEL MINING AND PROCESSING
WET)
GRAVEL
PRODUCT
SAND
PRODUCT
-------
WATER
MEDIA
MINE:
LEGEND;
ALTERNATE
ROUTE
HEAVY
MED? A
SEPARATION
WASH
AMD
SCREEN
1
MEDIA RECOVERY
WET
PROCESSING
GRAVEL PRODUCT
• SAND PRODUCT
¥
WASTE
SETTLING AID--
PONDS AND/OR
THICKENERS
EFFLUENT WATER
RECYCLE
FIGURE 17
AND GRAVEL MINING AND PROCESSING
( HMS }
-------
Water Use
Process water includes water used to separate, wash, and
classify sand and gravel. Incidental water is used for
non-contact cooling and dust suppression. Water used for
sand and gravel separation enters a rotary scrubber or is
sprayed via spray bars onto a vibratory inclined screen to
separate the sand and the clay from the gravel. The sand
slurry is further processed via hydraulic classification
where additional water is usually added. As the source of
the raw material constantly changes, so does the raw waste
load and the amount of water required to remove these
wastes.
The following tabulates process water use at selected
facilities:
Facility
1006
1012
1055
1391
5630
5656
5666
5681
!dS3 of product (gal/ton)
2500 (600)
9400 (2250)
3400 (820)
1430 (340)
1460 (350)
750 (180)
7400 (1800)
2000 (480)
Facilities 1012 and 5666 have markedly higher hydraulic
loads than the others because they use hydraulic suction
line dredges.
Facility 1006 discharges an average of 1900 1/min (500
gal/min) of pit water, or 208 1/kkg of product (50 gal/ton)
ranging from 0 to 5000 1/kkg (0-1200 gal/ton) depending on
the rainfall.
Waste water Treatment
The predominant method of treating process waste water is to
remove sand fines and clay impurities by mechanical
dewatering devices and settling basins or ponds. Removal of
-200 mesh sand and clay fines is much more difficult and
requires settling times that are usually not achievable with
mechanical equipment. Some facilities use settling aids to
hasten the settling process. The best facilities in this
subcategory are able to recycle the clarified water back to
the process. Water with a total suspended solids content
less than 200 mg/1 is generally clean enough to reuse in the
process. The following tabulates data from facilities which
recirculate their process water resulting in no discharge of
process waste water:
89
-------
Facility TSS (mcf/li.
1055 unknown
1235
1391
1555
3049
5617
5631
5674
unknown
4,550
15,000
5,000
unknown
unknown
unknown
Treatment
spiral classi-
fiers, 4-hectares
(10-acre) settling
basin
mechanical thick- 54
eners, settling
ponds
mechanical thick- 32
eners, cyclones,
2-hectares (5-acre)
settling basin
cyclones, 14-hectares
(35-acre) settling
basin
cyclones, vacuum 30
disc filter, 2-hectares
(S^acre) settling pond
with polymer floe
Output
TSS (ma/1)
25
35
dewatering screws,
settling ponds
unknown
dewatering screws, unknown
10-hectares (25-acre)
settling pond
dewatering screws, unknown
0.8-hectare (2-acre)
settling pond
Facilities 1012 and 5666 are hydraulic dredging facilities.
Slurry from these facilities is sent to a settling basin to
remove waste fines and clays. The decant from the settling
basin is returned to the wet pit to maintain a constant
water level for the dredge resulting in no discharge of
process water.
Lack of land to a major extent will impact the degree to
which a facility is able to treat its process waste water.
Many operations are able to use worked-out sand and gravel
pits as settling basins. Some have available land for
impoundment construction. The following lists the suspended
solids concentration of treated waste water effluents from
facilities discharging:
90
-------
Facility Treatment TSS,. mg/1
1006 dewatering screw, 55
settling ponds
104'4 dewatering screw, 154
settling pond
1056 settling ponds 25
1083 dewatering screw, 47
settling ponds
1129 dewatering screw, 44
settling ponds
5630 dewatering screw, 5
settling ponds
Facility 1981, using heavy-media separation, recovers the
magnetite and/or ferrosilicon pulp, magnetically separates
the media from the tailings, and returns the media to the
process. Separation tailings from the magnetic separator
are discharged to settling basins and mixed with process
water.
Pit pumpout and non-contact cooling water are usually
discharged without treatment. Facility 1006 discharges pit
pumpout water through the same settling ponds which handle
process water. Facility 1044 discharges non-contact cooling
water through the same settling ponds used for treating
process water. Dust suppression water is adsorbed on the
product and evaporated.
Effluents and Disposal
Half the facilities visited are presently recirculating
their process water resulting in no discharge.
Those facilities recirculating all process generated waste
water include:
1007 1059 1206 1391
1013 1084 1207 1555
1014 1200 1208 1629
1048 1201 1230 3049
1055 1202 1233 5622
1056 1203 1234 5631
1057 1204 1236 5656
1058 1205 1250 5674
The following facilities achieve no discharge to navigable
waters by perculation:
1231 5666
1232 5681
91
-------
The following facilities previously mentioned as recycling
all process generated waste waters declared that significant
perculation occurs in their ponds:
1057 1233 5656
1058 1234
Facilities 1005, 1012, 5670 dredge closed ponds on their
property and discharge all process waste waters back to the
pond being dredged. Only very large rainfalls would cause a
discharge from these ponds to navigable waters.
The rest discharge process water, characteristics of some
discharges are:
Flow TSS
1/kkg of product kq/kkq of product
Facility jgal/tonj (lb/1000 Ib)
1006 2500 (600) 0.14
1044 1670 (400) 0.26
1056 1750 (420) 0.04
1083 1040 (250) 0.05
1129 1150 (275) 0.05
5630 1170 (290) 0.006
Solid wastes (fines and oversize) are disposed of in nearby
pits or worked-out areas or sold. Clay fines which normally
are not removed by mechanical equipment settle out and are
routinely cleaned out of the settling pond. Facilities 1391
and 1629 remove clay fines from the primary settling pond,
allow them to drain to approximately 20 percent moisture
content, truck the wastes to a landfill site, and spread
them out to enhance drying.
92
-------
DREDGING WITH ON-LAND PROCESSING
Process Description
The raw material is extracted from rivers and estuaries
using a floating, movable dredge which excavates the bottom
sand and gravel deposit by one of the following general
methods: suction dredge with or without cutter-heads,
clamshell bucket, or bucket ladder dredge. After the sand
and gravel is brought on-board, primary sizing and/or
crushing is accomplished with vibrating or rotary screens,
and cone or gyratory crushers with oversize boulders being
returned to the water. The general practice in this
subcategory is to load a tow-barge, which is tied alongside
the dredge. The barge is transported to a land-ba sed
processing facility where the material is processed similar
to that described for wet processing of sand and gravel.
The degree of sand and gravel processing on-board the dredge
is dependent on the nature of the deposit and customer
demands for aggregate. Dredges 1010, 1052, 1051, extract
the raw material via clamshell or bucket ladder, remove
oversize boulders, size, and primary crush on-board. Figure
18 shows the basic material flow for these dredges. Dredges
1046 and 1048 extract via clamshell, but have no on-board
crushing or sizing. The extracted material for all the
above-mentioned dredges is predominantly gravel. This
gravel must undergo numerous crushing and sizing steps on
land to make a manufactured sand product which is absent in
the deposit.
Dredges 1011 and 1009 excavate the deposit with cutter-head
suction line dredges since the deposit is dominated by sand
and small gravel. Dredge 1011 pumps all the raw material to
an on-land processing facility. Dredge 1009, due to the
lack of demand for sand at its location, separates the sand
and gravel on-board the dredge with the sand fraction being
returned to the river. The gravel is loaded onto tow-barges
and transported to a land facility where wet processing is
accomplished. The dredges in this subcategory vary widely
in capital investment and size. Dredge 1046 consists of a
floating power shovel powered by a diesel engine which digs
the deposit and loads onto a tow-barge, A shovel operator
and a few deck hands are on-board during the excavation
which is usually only an eight-hour shift. Dredge 1009 is
much larger and sophisticated since it requires partial
on-board separation of sand and gravel. This dredge is
manned by a twelve-man crew per shift, with complete crew
live-in quarters and attendant facilities. This dredge
operates 24 hours/day.
93
-------
r
RAW
MATERIALS
«*££i
L.
SIZE
I
CRUSH
^
k (
«,
DREDGE
-
.
TOW __ „„,*£,„„.
BARGE PLANT
PRODUCT
OVERSIZE
FIGURE 18
SAND AND GRAVEL MINING AND PROCESSING
(DREDGING WITH ON-LAND PROCESSING)
-------
Raw Waste Loads
Raw wastes consist of oversize or unusable material which is
discarded at the dredge and undersize waste fines (-150
mesh) which are handled at the land-based processing
facility. The amount of waste material is variable
depending on the deposit and degree of processing. On the
average, 25 percent of the dredged material is returned to
the river. Waste fines at land facilities average 10
percent. The following tabulates waste loads at selected
operations:
At Dredge At_Land Facility
kg/kkg of feed kg/kkg of feed
gb/1000 Ibj Jib/1000 lb)^
460 100
1010 none 400
1011 none 150
1046 none 110
1048 none 120
1051 250 60
1052 180 120
Clay content of dredged sand and gravel, usually averaging
less than 5 percent, is less than that of land deposits due
to the natural rinsing action of the river. Unsaleable sand
fines resulting from crushing of gravel to produce a
manufactured sand represent the major waste load at the land
facilities.
Water Use
Water use at the land facilities is similar to wet
processing subcategory facilities. the wet processing
subcategory. Process water is used to separate, wash, and
classify sand and gravel. Incidental water includes
non-contact cooling and dust suppression. Water use at the
dredge depends on the excavation method. Some clamshell and
ladder bucket dredges do not use process water because there
is no on-board washing. Suction line dredges bring up the
raw material as a slurry, remove the aggregate, and return
the water to the river. Water use at land facilities is
variable depending on the raw material and degree of
processing as shown below:
95
-------
Facility 1/KJS3 of feed (gal/ton)
1009 2200 (530)
1010 1400 (340)
1046 1000 (240)
1048 3440 (825)
1051 1300 (320)
1052 1500 (360)
Water used for dust suppression averages 15 1/kkg (3.8
gal/ton) of gravel processed.
Waste Water Treatment
At dredge 1009, there is no treatment of the sand slurry
discharged to the river. Removal of waste fines at land
facilities with spiral classifiers, cyclones, mechanical
thickeners, or rake classifiers and settling basins, is the
method of process waste water treatment. These are similar
to methods used in the wet processing subcategory.
Facilities 1046, 1048, 1051 and 1052, by utilizing
mechanical devices and settling basins, recirculate all
process water thereby achieving no discharge. The following
is a list of treatment methods, raw waste loads, and treated
waste water suspended solids for these operations:
Treated Recycle
Raw Waste Load, Water,
Facility TSS (mg/1) Treatment TSS imq/1)
1046 8,500 dewatering 275
screw, cyclone,
drag classi-
fier, settling
basin
1 048 10,000 dewatering 50
screw,
cyclones,
settling basins
1051 9,000 dewatering 300
screw, drag
classifier,
settling basin
1052 7,500 dewatering 200
screw, drag
classifier,
settling basin
with flocculants
96
-------
Availability of land for settling basins influences the
method of process water treatment. Many operations use
worked-out sand and gravel pits as settling basins (Facility
1048) or have land available for impoundment. Facility 1010
is not able to recirculate under current conditions due to
lack of space for settling basins. Land availability is not
a problem at facilities 1011 and 1099.
Non-contact cooling water is typically discharged into the
same settling basins used for treating process water. Dust
suppression water is adsorbed onto the product and
evaporates,
Effluents and Disposal
Four of the seven facilities visited in this subcategory
have no discharge of process generated water. The remaining
three discharge process washwater. Effluent parameters at
two of these facilities are:
TSS TSS, kg/kkq of product
mg/1 (lb/1000 Ib)
1010 16,000 22
1009 50 0. 10
Sand fines (+200 mesh) are removed with mechanical devices
and conveyed to disposal areas. Clay fines and that portion
of the, silica fines smaller than 200 mesh, which settle out
in a settling basin, are periodically dredged and
stockpiled. Facility 1051 spends approximately 120 days a
year dredging waste fines out the primary settling pond.
These fines are hauled to a landfill area.
97
-------
DREDGING WITH ON-BOARD PROCESSING
Process Description
The raw material is extracted from rivers and estuaries
using a floating, movable dredge which excavates the bottom
sand and gravel deposit by one of the following general
methods: suction dredge, with or without cutter-heads,
clamshell bucket, or bucket ladder dredge. After the sand
and gravel is brought on-board, complete material processing
similar to that described in the wet process subcategory,
occurs prior to the loading of tow-barges with the sized
sand and gravel. Typical on-board processing includes:
screening, crushing of oversize, washing, sand
classification with hydraulic classifying tanks, gravel
sizing, and product loading. Numerous variations to this
process are demonstrated by the dredges visited. Dredges
1017 and 1247 use a rotary scrubber to separate the sand and
gravel which has been excavated from land pits, hauled to
the lagoon where the dredge floats, and fed into a hopper
ahead of the rotary scrubber. Dredge 1008 excavates with a
revolving cutter head suction line in a deposit dominated by
sand. The sand is separated from the gravel and deposited
into the river channel without processing. Only the gravel
is washed, sized, and loaded for product as there is little
demand for sand at this location. Dredge 1050 employs
bucket ladders, rough separates sand from gravel, sizes the
gravel, crushing the oversize, and removes deleterious
materials from the gravel by employing heavy media
separation (HMS). HMS media (magnetite/ferrous silica) is
recovered, and returned to the process. Float waste is
discharged into the river. Dredge 1049r a slack-line bucket
ladder dredge normally works a river channel. However,
during certain periods of the year it moves into a lagoon
where water monitors "knock down" the sand and gravel
deposit into the lagoon in front of the buckets. All of the
dredges pump river water for washing and sand
classification. Periods of operation are widespread for the
dredges visited. Dredge 1008 operates all year, 24 hours
per day (two-12 hour shifts). Dredge 1049 operates two 8
hour shifts for 10 months. Dredging for sand and gravel is
regulated under section 404 of the Act.
98
-------
INDUSTRIAL SAND
The amount of industrial sand produced accounts for only 7
percent of the total O.S. sand production, but represents 20
percent of the total dollar value for all sand products.
Sand produced for industrial purposes is used in the
following areas: glassmaking, molding, grinding and
polishing, blast sand, fire and furnace sand, locomotive
traction sand, filtration, oil hydrofracture, or ground
sand. The first two account for approximately 62 percent of
the total industrial sand production, 37 and 25 percent
respectively. The percentage of dollar values for each of
the types of industrial sand correlate closely to their
respective percentages of the production total. Forty
states produce one or more categories of industrial sands
with Illinois (16 percent). New Jersey (11.5 percent), and
Michigan (10 percent) claiming 37.5 percent of the total
output.
The three basic methods of extraction are:
(1) Mining of sand from open pits;
(2) Mining of sandstone from quarries; and
(3) hydraulic dredging from wet pits,
Once the raw material is extracted, the basic operations
involved in the production of all types of industrial sand
are classification and removal of impurities. The amount of
impurities in the raw material is dependent upon the
percentage of silica in the deposit. The subsequent level
of technology involved in the removal of these impurities
depends on the desired grade of product. Glass sand, for
example, requires a higher degree of purity than does
foundry sand.
Based on 15 facilities surveyed in seven states, the
industry was divided into the following subcategories:
(1) Dry Process (5 facilities surveyed);
(2) Wet Process (4 facilities surveyed) ; and
(3) Flotation Process (6 facilities surveyed).
Two of the wet process facilities also use flotation on a
small percentage of their finished product, and are included
in the flotation process subcategory. Production, in the
facilities contacted, ranges from 32,600 - 1,360,000 kkg/yr
(36,000 - 1,500,000 tons/yr) and facility ages vary from
less than one year to 60 years.
99
-------
INDUSTRIAL SAND, DRY PROCESS
Process Description
Approximately 10 percent of the industrial sand operations
fall into this subcategory, characterized by the absence of
process water for sand classification and beneficiation.
Typically, dry processing of industrial sand is limited to
scalping or screening of sand grains which have been
extracted from a beach deposit or crushed from sandstone.
Facilities 1106 and 1107 mine a beach sand which has been
classified into grain sizes by natural wind action on the
deposit. Sand, of a specific grain size, is trucked to the
facility where it is dried, cooled, coarse grain scalped,
and stored. Processing of beach sand which is excavated at
differing distances from the shoreline, enables the facility
to process a number of grain sizes which can be blended to
meet customer specifications.
Facilities 1109 and 1110 quarry a sandstone, crush, dry, and
screen the sand prior to sale as a foundry sand. Facility
1108 is able to crush, dry, and screen a sandstone of high
enough purity to be used for glassmaking. Most of the
facilities use a dust collection system at the dryer to meet
air pollution requirements. Dust collection systems are
either dry (cyclones and baghouses in facilities 1106, 1109
and 1110) or wet (wet scrubbers in facilities 1107 and
1108). Figure 19 shows a typical process for dry mining and
processing of industrial sand.
Raw Waste Loads
Raw wastes consist of oversize sandstone and undersize sand
fines at facilities 1108, 1109, and 1110. Waste at these
facilities averages less than 10 percent as shown below:
Facility kq/kkq of feed
41b/lppg_lbl_
1108 100
1109 115
1110 92
Wastes at facilities 1109 and 1107 are undersize or coarse
grained sand averaging about one percent of the feed to the
facility.
Water Use
No water is used to wash and classify sand in this
subcategory. Facilities 1108 and 1107 use a wet dust
100
-------
SANDSTONE
QUARRY
BEACH
DEPOSIT
LEGEND:
ALTERNATE
ROUTE
CRUSH
DUST
COLLECTION
(WET AND DRY)
DRY
SCREEN
WASTE
FINES
WASTE
FINES
FIGURE 19
INDUSTRIAL SAND MIMING AND PROCESSING
(DRY)
PRODUCT
-------
collection system at the dryer. Water flows for these two
wet scrubbers are shown below:
Wet Scrubber Water Use Facility 1107
total flow, 1/min 9460 (2500)
(gal/min)
amount recirculated, 9390 (2480)
1/min (gal/min)
amount discharged 0
1/min (gal/min)
amount makeup, 1/min 76 (20)
(gal/min)
Although the five facilities surveyed in this subcategory
did not use non-contact cooling water, it may be used in
other facilities.
Waste Water Treatment
Wet scrubber water at facility 1108 is not treated prior to
discharge. Scrubber water at facility 1107 is treated in a
settling pond where suspended solids are settled and the
clarified decant is returned to the scrubber, resulting in
no discharge.
Effluents and Disposal
Facilities 1106, 1109, and 1110 do not have any waterborne
wastes. Facility 1107 recirculates all wet scrubber water
to the scrubber. Facility 1108 discharges wet scrubber
water without any treatment as shown below:
Flow, I/day (GPD) 166,000 (43,000)
TSS, mg/1 33,000
Solid waste (oversize and sand fines) at all of the
facilities is landfilled.
102
-------
INDUSTRIAL SAND, WET PROCESS
Process Description
Mining methods vary with the facilities in this subcategory.
Facility 3066 scoops the sand off the beach, while facility
1989 hydraulically -mines the raw material from an open pit.
Facility 1019 mines sandstone from a quarry. At this
facility water is used as the transport medium and also for
processing. Facility 1019 dry crushes the raw material
prior to adding water. An initial screening is usually
employed by most facilities consisting of a system of
scalpers, trommels and/or classifiers where extraneous
rocks, wood, clays, and other matter is removed. Facility
1102 wet mills the sand to produce a finer grade of
material. At all facilities water is filtered off, and the
sand is then dried, cooled, and screened. Facility 3066
magnetically separates iron from the dried product. The
finished product is then stored to await shipment. Facility
3066 mines a feldspathic sand. This, however, does not
require any special treatment nor different method of
processing. A general wet process diagram for mining and
processing of industrial sand is given in Figure 20.
Raw Waste Loads
At facility 3066, approximately one percent solid wastes
(tree roots, rocks, clays, etc.) are separated from the
sand. These amount to less than 0.5 kg/kkg (lb/1000 Ib) of
product. Both facilities 1102 and 1019 pump process waste
materials, mainly clays, into their settling pond systems.
This amounts to 30 and 36 kg/kkg respectively, of the
material processed.
Water Use
There is no predetermined quantity of water necessary for
washing industrial sands as the amount required is dependent
upon the impurities in the deposit. Typical amounts of
process water are given as follows:
Facility 1/kkg of product (gal/tonj
1019 12,000 (2,880)
1102 7,260 (1,740)
1989 5,000 (1,200)
3066 170 (40)
Facility 1102 also uses water (quantity unknown) in a wet
scrubber. Facility 1989 hydraulically mines the raw
material using 3600 1/kkg of product (860 gal/ton). The
remaining 1400 1/kkg of product (340 gal/ton) is used for
103
-------
DRY PIT
o
-ts.
WET PIT
SCREEN
DESLIMING
AND
DEWATERING
THICKENER
OR
CLARIFIER
MILL
CLASSIFYING
PRODUCT
I FLOCCULATING
AGENT
I I RECYCLE WATER
SETTLING POND
FIGURE 20
INDUSTRIAL SAND MINING AND PROCESSING
(WET)
-------
washing and classifying. Incidental water use includes
boiler and non-contact cooling water.
Waste Water Treatment
Under normal conditions facilities 1019, 1989, and 3066 are
able to recirculate all process water by using mechanical
devices and the settling of suspended solids in containment
ponds. During periods of heavy rainfall, area runoff into
the containment ponds cause a temporary discharge. Facility
1102 discharges process water, including wet scrubber water,
after treatment in settling ponds. The treatment methods
used by the facilities are shown as follows:
Treatment
thickener, clarifier, contain-
ment pond
1102 cyclone, thickener and floccu-
lant, settling ponds
1989 containment pond
3066 containment pond
Effluents and Disposal
There is no discharge of process water from three of the
four facilities surveyed under normal operating conditions.
Some facilities such as facility 1102, must periodically
clean their settling ponds of the fines which have
accumulated therein. The material recovered is either sold,
stockpiled, or used as landfill.
105
-------
INDUSTRIAL SAND, FLOTATION PROCESS
Process Description
Within this subcategory, three flotation techniques are
used:
(1) Acid flotation to effect removal of iron oxide and
ilmenite impurities,
(2) Alkaline flotation to remove aluminate bearing
materials, and
(3) Hydrofluoric acid flotation for removal of feldspar.
In acid flotation, sand or quartzite is crushed, and milled
into a fine material which is washed to separate adhering
clay-like materials. The washed sand is slurried with water
and conveyed to the flotation cells. Sulfuric acid,
frothers and conditioning agents are added and the silica is
separated from iron-bearing impurities. The reagents
include sulfonated oils, terpenes and heavy alcohols in
amounts of up to 0.5 kg/kkg (1 Ib/ton) of product. In the
flotation cells, the silica is depressed and sinks, and the
iron-bearing impurities are "floated" away. The purified
silica is recovered, dried and stockpiled. The overflow
containing the impurities is sent to the wastewater
treatment system.
In alkaline flotation, the process is very similar to that
described above with the following difference: before the
slurried, washed sand is fed to the flotation cell, it is
pretreated with acid. In the cell, it is treated with
alkaline solution (aqueous caustic, soda ash or sodium
silicate), frothers and conditioners. The pH is generally
maintained at about 8.5 (versus about 2 in acid flotation).
Otherwise, the process is the same as for acid flotation.
Materials removed or "floated" by alkaline flotation are
aluminates and zirconates.
In hydrofluoric acid flotation operations, after the raw
sand has been freed of clays by various washing operations,
it is subjected to a preliminary acid flotation of the type
described above. The underflow from this step is then fed
to a second flotation circuit in which hydrofluoric acid and
terpene oils are added along with conditioning agents to
float feldspar. The underflow from this second flotation
operation is collected, dewatered and dried. The overflow,
containing feldspar, is generally sent to the waste water
treatment system. A flowsheet for the three flotation
processes is given in Figure 21.
106
-------
HF FLOTATION PROCESS-HF-
ALKALINE FLOTATION PROCESS- CAUSTIC -
{FLOTATION AGENTS, _
FROTHERS, CONDITIONERS
SULFUR1C ACID
WATER
MINE
CRUSH
AND
GRIND
DESL1ME
-S5S
RECYCLE
U
VENT
t
DUST
COLLECTORS
WET AND
DRY
CONDITION
AND
FLOTATION
DEWATER
AND
DRY
HF FLOTATION
FELDSPAR
RECOVERY
LAGOONS AND/OR THICKENERS
EFFLUENT
FIGURE 21
INDUSTRIAL SAND MINING AND PROCESSING
(FLOTATION PROCESSES)
MAGNETIC
SEPARATION
•PRODUCT
„ FELDSPAR
CO-PRODUCT
IRON-BEARING
SOLID: WASTE
-------
Raw Waste Load
Process raw wastes from all three flotation processes
consist of muds separated in the initial washing operations,
iron oxides separated magnetically and materials separated
by flotation. The amounts of wastes are given below.
Waste
Source
Amount kg/kkg of raw material jib/1000_
1101 1019 1980 1103 5691 5980
Clays Washing
Flotation Flotation
tailings
Iron Magnetic
oxides separation
Acid & Flotation
flotation
agents*
Fluorides HF Flota-
(as HF) tion tailings
10
50
none
not
given
530
20
none
not
given
48
60
12
(24)
0.055
(0.11)
none none
none
36
140
none
not
given
none
3
17
none
not
given
none
165
135
34
0.3
0,45
* Generally flotation agents consist of oils and petroleum
sulfonates and in some cases, minor amounts of amines.
Water Use
Facility water uses are shown below. Most of the water is
recycled. The unrecycled portions of the waters for the
alkaline and HF processes are those used for the flotation
steps. For the acid flotation at least two facilities (1101
and 1980) have achieved total recycle. Facility 1019
impounds process discharge as wet sludge. Facility 1103
returns process waste water to the same wet pit where the
raw material is extracted, adding make-up water for losses
due to evaporation.
Facility JTHM
1/kkg of product
1019 1980 1103 5691 5980
Process
Recycle
Process
Discharge
Scrubber
(recycle)
Total
25,400 2,580 23,200 27,300 8,400 24,200
none none* none 6,830 5,250 1,760
none none
50 none
(10)
none
none
25,400 2,930 23,250 34,130 13,650 26,060
* As impounded wet sludge
108
-------
Waste Water Treatment
At the acid flotation facilities, facilities 1101, 1019,
1980, and 1103, all process wash and flotation waste waters
are fed to settling lagoons in which muds and other
suspended materials are settled out. The water is then
recycled to the process. Facilities 1101 and 1980 are in
their first year of operation.
At the alkaline flotation facility 5691, the washwaters are
combined and fed to a series of settling lagoons to remove
suspended materials and then partially recycled. Alum is
used as a flocculating agent to assist in settling of
suspended materials, and the pH is adjusted prior to either
recirculation or discharge.
At facility 5980, the only facility found that uses HF
flotation, all waste waters are combined and fed to a
thickener to remove suspended materials. The overflow
containing 93.2 percent of the water is recycled to the
process. The underflow containing less than 7 percent of
the water and essentially all of the suspended materials is
fed to a settling lagoon for removal of suspended solids
prior to discharge. The pH is also adjusted prior to
discharge. Fluoride ion concentration in the settled
effluent ranges from 1.5 to 5.0 mg/1.
Effluent and Disposal
Facilities 1101 and 1980 are presently producing products of
a specific grade which allows them to totally recycle all
their process water. In two other facilities, facilities
1019 and 1103, all, facility waste waters leave the
operations either as part of a wet sludge which is land
disposed or through percolation from the settling ponds.
There is no point source discharge from any of the acid
flotation operations.
The composition of the intake and final effluent waters for
the alkaline flotation facility 5691, are presented below.
After neutralization of the added alkali and settling, the
quality of the effluent is very similar to that of the
intake.
Also shown below are the compositions of the intake and
effluent for facility 5980, the HF flotation process
facility.
109
-------
Pollutants Facility 5691 Facility 5980
(mq/1) Intake Effluent Intake Effluent
pH 7,8 5.0 7.6 7.0-7.8
TDS 209 192
TSS 5 4 10 15-50
Sulfate 9 38 285 27-330
Oil and Grease <1.0 <1.0 '
Iron 0.1 0.06
Nitrate 23 0-9
Chloride 6 2 57-7 6
Fluoride —^ 0.8 1.8-4.6
Phenols Not detectable
110
-------
Pollutants Facility 5691 Facility 5980
(mq/1) Intake Effluent Intake Effluent
pH 7.8 5.0 7.6 7.0-7.8
TDS 209 192 --- ---
TSS 54 10 15-50
Sulfate 9 38 285 27-330
Oil and Grease <1.0 <1.0 — - ---
Iron 0.1 0.06 --- ---
Nitrate — --- 23 0-9
Chloride --- --- 62 57-76
Fluoride --- — •* 0.8 1.8-4.6
Phenols Not detectable
110
-------
Waste Water Treatment
At the acid flotation facilitiesp facilities 1101, 1019,
1980, and 1103, all process wash and flotation waste waters
are fed to settling lagoons in which muds and other
suspended materials are settled out. The water is then
recycled to the process. Facilities 1101 and 1980 are in
their first year of operation.
At the alkaline flotation facility 5691, the washwaters are
combined and fed to a series of settling lagoons to remove
suspended materials and then partially recycled. Alum is
used as a flocculating agent to assist in settling of
suspended materials, and the pH is adjusted prior to either
recirculation or discharge.
At facility 5980, the only facility found that uses HF
flotation, all waste waters are combined and fed to a
thickener to remove suspended materials. The overflow
containing 93.2 percent of the water is recycled to the
process. The underflow containing less than 7 percent of
the water and essentially all of the suspended materials is
fed to a settling lagoon for removal of suspended solids
prior to discharge. The pH is also adjusted prior to
discharge. Fluoride ion concentration in the settled
effluent ranges from 1.5 to 5.0 mg/1.
Effluent and Disposal
Facilities 1101 and 1980 are presently producing products of
a specific grade which allows them to totally recycle all
their process water. In two other facilities, facilities
1019 and 1103, all facility waste waters leave the
operations either as part of a wet sludge which is land
disposed or through percolation from the settling ponds.
There is no point source discharge from any of the acid
flotation operations.
The composition of the intake and final effluent waters for
the alkaline flotation facility 5691, are presented below.
After neutralization of the added alkali and settling, the
quality of the effluent is very similar to that of the
intake,
Also shown below are the compositions of the intake and
effluent for facility 5980, the HF flotation process
facility*
109
-------
GYPSUM
Although both underground mining and quarrying of gypsum is
practiced, quarrying is the dominant method of extraction.
General procedure for gypsum processing includes crushing,
screening, and processing. An air-swept roller process
facility is most commonly used for the latter. Two
facilities use heavy media separation for beneficiation of a
low-grade gypsum ore prior to processing. Ninety percent of
all gypsum ore is calcined into gypsum products including
wall board, lath, building plasters and tile. The remaining
10 percent is used as land plaster for agricultural purposes
and in the cement industry for portland cement
manufacturing. The manufacture of gypsum products is not
covered in this report.
Thirty-six companies mined crude gypsum at 65 mines in 21
states in 1972. Five major companies operate 32 mines from
which over 75 percent of the total crude gypsum is produced.
Based on 5 facility visits and 36 facility contacts {63% of
the total), the industry was divided into the following
subcategories:
(1) Dry (3 visits, 32 contacts)
(2) Wet scrubbing (1 visit, 3 contacts)
(3) Heavy media separation (1 visit, 1 contact)
The facilities studied were in all regions of the nation
representing various levels of yearly production and age.
GYPSUM, DRY PROCESS
Process Description
Underground mining is carried out in most mines by the room-
and-pillar method, using trackless mining equipment. In
quarrying, stripping is accomplished both with draglines and
tractors. Quarry drilling methods are adapted to meet local
conditions. Low-density, slow-speed explosives are employed
in blasting. Loading is commonly done with diesel or
electric shovels. Transportation may be by truck or rail
from quarry to facility. Primary crushing is done at most
quarries using gyratory and jaw crushers and impact mills.
Secondary crushing is usually accomplished by gyratory
units, and final crushing is almost exclusively by
hammermills. The common unit for grinding raw gypsum is the
air-swept roller process facility. Ground gypsum is usually
termed "land plaster11 since in this form it is sacked or
sold as bulk for agricultural purposes. A typical process
diagram is shown in Figure 22.
Ill
-------
VENT
DRY
DUST
COLLECTOR
MINE
OR
QUARRY
PRIMARY
AND
SECONDARY
CRUSHING
GRINDING
PRODUCT
PIT PUMPOUT
FIGURE 22
GYPSUM MINING AND PROCESSING
(DRY)
-------
Raw Waste Loads
The raw wastes for all facilities consist of oversize
material and gypsum dust from grinding. Many facilities
work a gypsum deposit of such purity that all the ore fed to
the crushers is ground to land plaster, except for a small
percentage (<556) lost to dust collection equipment (e.g.
cyclones or bag houses). Facility 1977 discards 97,500
kkg/yr (1,075,000 tons/yr) of waste rock at the quarry site.
This is 24 percent of the ore quarried.
Water Use
No process water is used in the mining, crushing, or
grinding of gypsum. However, mine or quarry pumpout is
necessary in a number of facilities. Pumpout is not related
to a production unit of gypsum, and the flow is independent
of facility processing capacities. Most pumpouts are
controlled with a pit or low-area sump which discharges when
the water level reaches a certain height. Incidental water
use includes non-contact cooling water for crusher bearings.
Facility data for non-contact cooling water use is given
below:
Facility
1042
1700
1997
1999
Waste Water Treatment
1/kkg of product (gal/ton)
246
58
250
4.5
(59)
(60)
(1)
Mine or quarry pumpout is generally discharged without
treatment. Most facilities discharge non-contact cooling
water without treatment.
Effluents and Disposal
There is no process generated waste water discharge except
mine water discharge in this subcategory. Effluent data for
some facilities discharging mine or quarry water are given
as follows:
113
-------
facility
1041
1042
1112
1997
1999
flow,
I/ day
TSS,
4.4 (1.17)
6.4 (1.70)
5.1 (1.35)
0.68 (0.18)
6.5 (1.71)
6
4
14
5
24
7.7
7.8
8.1
7.9
7.4
Non-contact cooling water discharge from these facilities is
given below:
facility
1041
1042
1112
1997
1999
flow,l/kkg of
product (gal/ton)
none
246 (59)
none
250 (60)
4.5 (1)
TSS
not known
6
130
pH
not known
7.9
5
Land plaster dust collected in cyclones is either recycled
to the process or hauled away and landfilled.
GYSPUM, WET SCRUBBING
Process Description
Facilities in this subcategory employ identical gypsum
mining and processing methods as those used in the dry
subcategory, except for the addition of wet scrubbers for
air pollution control. Instead of dry dust collectors at
the grinding mills (see Figure 22, facilities in this
subcategory use wet scrubbers to remove land plaster dust
created by hammerprocess facility operations.
Raw Waste Loads
Oversize wastes in this subcategory are similar to those in
the dry subcategory. Land plaster waste fines are collected
with wet scrubbers and discharged as a slurry. The amounts
of raw waste fines so discharged from the scrubbers are:
.facility 1776
kg/kkg of product 0.06
(lb/1000 Ib)
1995
6.6
1998
0. 12
Wet scrubber make-up water for facility 1998 is sea water
containing a high amount of dissolved and suspended solids.
114
-------
Water Use
The only process water in this subcategory is that used for
wet scrubbing. Quarry pumpout, while not found at the three
facilities visited,.is practiced by a number of facilities
in this subcategory. Incidental water use includes non-
contact cooling water for crusher bearings, as described in
the dry subcategory. The following is water used for wet
scrubbing at the facilities:
facility 1/kkg of product (gal/ton)
1776 2,230 (530)
1995 5,950 (1,430)
1998 2,780 (670)
Waste Water Treatment
Facilities 1998 and 1995 do not treat the wet scrubber
discharge. Facility 1776 impounds the wet scrubber effluent
prior to final discharge. Quarry pumpout water and non-
contact cooling water usually receive no treatment prior to
discharge.
Effuents and Disposal
wet scrubber effluents are shown below:
TSS
kq/kkq of product
facility pj /lb/10_00 Ib)
1776 7.9 0.12
1995 unknown 6.6
1998 7.7 0.13
These are the total raw waste loads at facilities 1995 and
1998 and one-half of the raw waste load at facility 1776.
Quarry pumpout and non-contact cooling water effluents and
waste disposal are similar to those in the dry subcategory.
GYPSUM, HEAVY MEDIA SEPARATION
Process Description
Two facilities at the same general location beneficiate
crude gypsum ore using heavy media separation (HMS) prior to
processing. Both facilities follow the same process which
includes quarrying, primary and secondary crushing,
screening and washing, heavy media separation, washing,
processing of float gypsum ore and stockpiling of sink
dolomitic limestone. Magnetite and ferrous silica are used
115
-------
in both facilities as the separation media, with complete
recirculation of the media or pulp. A process flow diagram
is shown in Figure 23.
Raw Waste Loads
At facility 1100 raw waste consists of dolomitic limestone
which is separated via heavy media separation, dewatered,
and stockpiled for construction aggregate or landfill
material. The amount of this waste is 500 kg/kkg (lb/1000
Ib) of product. Additional wastes include fines generated
during crushing which are washed out through screens, and
allowed to settle in a settling basin. No information was
available on the quantity of waste fines.
Water Use
Facility 1100 uses 1270 1/kkg (305 gal/ton) of ore processed
in heavy media separation screening and washing which
accounts for all process water. Additional water includes
quarry pumpout. During periods of heavy rainfall, a
discharge of up to 189,000 I/day (50,000 GPD) of quarry sump
water may occur. As is typical with quarry pumpout,
discharge is controlled by a sump, located at the low end of
the quarry. Facility 1100 does not use non-contact cooling
water for gypsum beneficiation.
Waste Water Treatment
All process water used for heavy media separation at
facility 1100 and the one other facility in this subcategory
is re-circulated through settling basins, an underground
mine settling sump, and returned to the separation circuit,
resulting in no discharge of process waste water. In the
recycle circuit, the HMS media (magnetite/ferrous silica) is
reclaimed and is reused in the separation process. Quarry
pumpout at facility 1100 is discharged to a settling ditch
which flows to a company owned marsh prior to discharge,
thereby achieving an effective settling of suspended solids.
Effluents and Disposal
There is no waterborne process water effluent in this
subcategory. At facility 1100, only quarry water is
discharged intermittently shown below:
I/day (GPD) 0-189,000 (0-50,000)
TSS, mg/1 60
pH 7.8
116
-------
RECYCLE
WATER
SCREEN
AND
POND
RECYCLE
WATER
RECYCLE
WATER
HEAVY
MEDIA
SEPARATION
WASH
MEDIA
RECOVERY
GRIND
•PRODUCT
SUMP
RECYCLE
TO PROCESS
FIGURE 23
GYPSUM MINING-' AMD PROCESSING
-------
Part of the waste rock from the HMS is sold as road
aggregate, with the remainder being landfilled in old
worked-out sections of the quarry. Waste fines at facility
1100 settle out in the primary settling basin and must be
periodically dredged. This waste is hauled to the quarry
and deposited.
118
-------
This category of materials encompasses three basic types of
materials produced by three different processes:
(1) bituminous limestone which is dry quarried;
(2) oil impregnated diatomite produced by dry methods;
(3) gilsonite and other bituminous shales produced by wet
processes.
BITUMINOIUS LIMESTONE
Process Description
Bituminous limestone is dry surface mined, crushed, screened
and shipped as product. A process flow sheet is given in
Figure 24.
Raw Waste Load
The raw wastes from these operations consist entirely of
overburden removed during the mining operations. This
material is a solid waste and amounts to 300 kg/kkg of
product.
Water Usage, Treatment and Effluent
No water is used in these operations, and hence there is no
need for waste water treatment and no waterborne effluent,
OIL IMPREGNATED DIATOMITE
Process Description
This material is produced at only one site. Oil impregnated
diatomite is surface mined, crushed, screened and then
calcined (burned) to free it of oil. The calcined material
is then ground and prepared for sale. The only process
water usage is a wet scrubber used to treat the vent gases
from the calcination step. The scrubber waters are
recycled. A process flowsheet is given in Figure 25.
Raw Waste Load
There are no process solid or waterborne wastes.
Water Use
Facility water use consists of 1800 1/kkg (420 gal/ton) of
product for scrubber makeup water. The scrubber water is
lost by evaporation.
119
-------
SURFACE
MINING
CRUSHING
SCREENING
PRODUCT
to
O
OVERBURDEN
(SOLID WASTE)
FIGURE 2 4
BITUMINOUS LIMESTONE MINING AND PROCESSING
-------
VENT
MAKE-UP WATER'
SURFACE
MINING
CRUSHING
AND
SCREENING
WET
SCRUBBING
CALCINATION
GRINDING
-PRODUCT
FIGURE 25
OiL IMPREGNATED DIATOMITE MINING AND PROCESSING
-------
Treatment and Effluent
There is no treatment required as there is no waterborne
effluent.
GILSONITE
Process Description
Gilsonite is mined underground. The ore is conveyed to the
surface as a slurry and separated into a gilsonite slurry
and sand, which is discarded as a solid waste. The
gilsonite slurry is screen separated to recover product.
Further processing by centrifuge and froth flotation recover
additional material. These solids are then dried and
shipped as product. A process flowsheet is given in Figure
26.
Raw Waste Load
Raw wastes consist of sand, process water and mine pumpout
waters.
Water Use
Facility water use is given below. A considerable amount of
intake water is used for non-process purposes (i.e.,
drinking and irrigation) . All process and mine pumpout
waters are currently discharged.
1/kkg of product (gal/ton^
intake 5,700 (1,400)
process 3,400 (820)
mine pumpout 470 - 1,800 (110-430)
drinking and
irrigation 2,300 (550)
Effluent
The compositions of the intake water, the discharged
facility process water and the mine pumpout water are listed
below. There is a considerable concentration of suspended
solids in the mine pumpout water. These discharges are
currently being eliminated. The process and mine pumpout
waters currently discharged will soon be employed on site
for other purposes.
122
-------
LO
WATER
MINE
SOLIDS
SEPARATOR
SCREEN
SCREEN
COLLECTOR
CENTRIFUGE
SAND
(SOLID WASTE)
VENT
WATER-
METHANOL
t
WET
SCRUBBER
FLOTATION
DRYER
POND
RECYCLE
TO PROCESS
FIGURE 26
GILSONITE MINING AND PROCESSING
PRODUCT
-------
Concentr ati on (mq/1)
intake effluent mine pumpout
Suspended solids
BOD
PH
TDS
Turbidity
Arsenic
Barium
Cadmium
Chloride
sulfate
33
35
7.7
401
17
43
8,2
2949
<0.001
0.15
363
3375
12
7.9 - 8,1
620
70 JTU
0.01
<0.01
0.004
8.8
195
124
-------
ASBESTOS AND WOLLASTONITE
ASBESTOS (SIC 1U99)
Four states produce asbestos; California, with 6956 of the
total production, is the leader, followed in order by
Vermont, Arizona, and North Carolina, The California and
Vermont facilities mine a chrysotile asbestos, while the
North Carolina deposit is an anthophyllite asbestos. Major
uses for asbestos fiber include construction, floor tile,
friction products, paper and asphalt felts.
Processing of asbestos ore principally involves repeated
crushing, fiberizing, screening, and air separation. Five
facilities mine and process asbestos in the United States.
Based on information from all five facilities two
subcategories are established for asbestos mining and
processing:
(1) Dry processing asbestos (4 facilities)
(2) Wet processing asbestos (1 facility)
ASBESTOS, DRY PROCESS
Process Description
Asbestos ore is usually extracted from an open pit or
quarry. At three facilities the fiber-bearing rock is
removed from an open pit. At facility 1061 the ore is
simply "plowed", allowed to air-dry, and the coarse fraction
is screened out from the millfeed.
After quarrying, the asbestos ore containing approximately
15% moisture is crushed, dried in a rotary dryer, crushed,
then sent to a series of shaker screens where the asbestos
fiber are separated from the rock and air classified
according to length into a series of grades. The collection
of fibers from the shaker screens is accomplished with
cyclones, which also aid in dust control. Figure 27
illustrates process flow for a dry asbestos operation.
Raw Waste Loads
Asbestos processing involves fiber classification based on
length, and as such, the raw waste loads consist of both
oversize rock and undersize asbestos fibers which are
unusable due to their length (referred to as "shorts"). At
facility 1061 28 percent of the asbestos ore is rejected as
oversize waste. At the processing facility another 65
percent of the feed are unusable asbestos fiber wastes which
must be disposed of.
125
-------
to
QUARRY
1
PUMf
«J»*EJ*
PRIMARY
CRUSHER
DRY
DUST
COLLECTOR
!
DRY
AIR
NHrgggl
SECONDARY
CRUSHER
i i
5OUT OVERSIZE
WASTE
II JIL iggT
DRY
DUST
COLLECTOR
I
SCREEN
iwnnQ^I
GRADE
WATER »"[
1
WASTE
FINES
PRODUCT
FIGURE 27
ASBESTOS MINING AND PROCESSING
(DRY)
-------
Water Use
No process water is used for the dry processing of asbestos
at any of the four facilities in this subcategory. Facility
3052 must continuously dewater the quarry of rain and ground
water that accumulates. The flow is from 380 1/min to 2270
1/min {100 to 600 gal/min)depending on rainfall. The
quantity of discharge is not related to production rate of
asbestos. Facility 1061 uses water for dust suppression
which is sprayed onto the dry asbestos tailings to
facilitate conveying of tailings to a waste pile. The water
absorbed in this manner amounts to 17 1/kkg of tailings (4
gal/ton).
Waste Water Treatment
Facility 3052 treats their quarry pumpout discharge with
sulfuric acid (approximately 0.02 mg/1 of effluent) to lower
the pH of the highly alkaline ground water that collects in
the quarry. At all facilities, both at the mine and
facility site, there exists the potential of rainwater
runoff contamination from asbestos waste tailings. Facility
1061 has constructed diversion ditches, berms, and check
dams to divert and hold area runoff from the waste tailing
pile. Due to soil conditions, water that collects in the
check dams eventually percolates into the soil thereby
resulting in no discharge to surface waters.
Effluents and Disposal
Facility 3052 discharges quarry pumpout water on a
continuous basis. The following tabulates analytical data
for facility 3052ls quarry discharge after treatment with
H2SO4:
flow, I/day (mgd) 545,000-3,270,000 (0.144*0.864)
TSS, mg/1 2.0
Fe, mg/1 0.15
pH 8.4-8.7
asbestos (fibers/liter) 1.0 - 1.8 x 10*
Waste asbestos tailings are stockpiled at all facilities.
127
-------
ASBESTOS, WET PROCESS
Process Description
The only facility in this subcategory, facility 1060, mines
the asbestos ore from a quarry located approximately 50
miles from the processing facility. The ore is "plowed" in
horizontal benches, allowed to air-dry, coarse fractions
screened out, and transported to the facility for
processing. At the facility, processing consists of
screening, wet crushing, fiber classification, filtering,
and drying. Figure 28 illustrates process flow at facility
1060.
Raw Waste Load
Raw waste consists of oversize rock which is discarded at
the quarry site and undersize waste asbestos ("shorts")
which are unsaleable. The undersize waste fibers represent
30 percent of the total ore processed. No data on amount of
oversize wastes were available.
Water Use
Process water is used for wet processing and classifying of
asbestos fibers. Facility 1060 uses 4,300 1/kkg (1,025
gal/ton) of asbestos milled. Approximately 4 percent of the
water is incorporated into the end product which is a filter
cake of asbestos fibers (505t moisture by weight) . Eight
percent is lost in the tailings disposal. Sixty eight
percent is recirculated back into the process, and 20
percent is eventually discharged from the facility. The
following tabulates estimated process water use at facility
1060:
1/kkcr of feed (gal/ton)
process water 4,300 (1,025)
water lost with product 150 (36)
water lost in tailings 350 (84)
water recirculated 2,900 (700)
water discharged to
settling pond 860 (205)
This facility is unable to recirculate the water from the
settling pond because of earlier chemical treatment given
the water in the course of production of a special asbestos
grade. The recirculation of this effluent would affect the
quality of the special product. In addition to process
water, facility 1060 uses 2,100 1/kkg of feed (500 gal/ton)
of non-contact cooling water, none of which is recirculated.
128
-------
QUARRY
N>
MAKE-UP
WATER
CRUSH
AND
SCREEN
DEWATER
RECYCLE
CLASSIFY
•SB*
FILTER
VENT
WASTE DUMP
POND
VENT
DRY
PRODUCT
FILTER
DRY
ESPECIAL PRODUCT
ASBESTOS
FIGURE 28
AND PROCESS!
(V/liT
-------
Waste Water Treatment
The process water discharge is treated in settling/percola-
tion ponds. Suspended asbestos fibers settle out in the
primary settling pond prior to decanting the clarified
effluent to the secondary settling/percolation pond.
Facility 1060 does not discharge to surface waters but uses
percolation as a form of waste water treatment.
Non-contact cooling water is not treated prior to discharge.
Runoff from asbestos tailings at the facility and the quarry
is controlled with diversion ditches, berms, and check dams.
All facility drainage is diverted to the
settling/percolation ponds.
Effluents and Disposal
No process water is discharged to surface water at facility
1060. Data on the waste stream to the percolation pond
includes the following:
Intake Discharge to
Well Water Percolation Pond
flow, 1/kkg feed(gal/ton) unknown 856 (205)
total solids, mg/1 3^3 1,160
pH 7.5 7.8
magnesium, mg/1 14 48
sodium, mg/1 44 345
chloride, mg/1 19 104
nickel, mg/1 0.02 0.1
Asbestos fiber tailings are stockpiled near the facility
where the water is drained into the settling/percolation
ponds. After some drying, the tailings are transported and
landfilled near the facility in dry arroyos or canyons.
Check dams are constructed at the lower end of these filled-
in areas.
The primary settling pond must be periodically dredged to
remove suspended solids (primarily asbestos fibers). This
is done with a power shovel, and the wastes are piled along-
side the pond, allowed to dry, and landfilled.
130
-------
WOLLASTONITE (SIC 1499)
There is only one producer of wollastonite in the U.S.
Process Description
Wollastonite ore is mined by underground room and pillar
methods, and is trucked to the processing facility.
Processing is dry and consists of 3 stage crushing, with
drying following primary crushing. After screening, various
sizes are fed to high-intensity magnetic separators, to
remove garnet and other ferro-magnetic impurities. The
purified wollastonite is then ground in pebble or attrition
mills to the desired product sizes. A general process
diagram is given in Figure 29.
Raw Waste Load
Of the total amount of wollastonite ore mined, approximately
50 percent, or 70,000 - 80,000 tons/yr, is waste. This
waste material is stocked for future use. In wollastonite
processing, waste is generated in the magnetic separators,
with garnet and some sand being sold as by-products. The
rest is sent to a waste pile.
Water Use
Municipal water serves as the source for the sanitary and
non-contact cooling water used in the facility. This
amounts to 235 1/kkg of product (56 gal/ton).
Waste Water Treatment
Non-contact cooling water is discharged with no treatment to
a nearby river.
Effluent and Disposal
Solid wastes generated in mining are stocked and eventually
used. Processing wastes are sent to a waste pile, with
garnet and some sand sold as by-product. Non-contact
cooling water is discharged untreated. The limitations on
this discharge as established by the Federal discharge
permit are:
Average Min.-Max.
Temperature 11°C 10-17°C
(52°F) (51-62°F)
pH 6-9
131
-------
MINE
'••»ig>
CRUSH
AMD
SCREEN
—•iflBB*
DRY
"• can
CRUSH
AND
SCREEN
.••in ggB
MAGNETIC
SEPARATORS
— • 9»
MILL
AND
CLASSIFY
PRODUCT
WASTEPILE
FIGURE 29
WOLLASTONITE MINING AND PROCESSING
-------
LIGHTWEIGHT AGGREGATE MINERALS (SIC 1499)
PERLITE
New Mexico produces 87 percent of the U.S. crude perlite.
Three of four major perlite producers in New " Mexico were
visited and analyzed. All U.S. perlite facilities are in
the same geographic region, and the processes are all dry.
Process Description
All the operations are open pit quarries using either
front-end loaders or blasting to remove the ore from the
quarry. The ore is then hauled by truck to the mills for
processing. There the ore is crushed, dried, graded
(sized), and stored for shipping. A general process diagram
is given in Figure 30.
Perlite is expanded into lightweight aggregate for use as
construction aggregate, insulation material, and filter
medium. Expansion of perlite is accomplished by injection
of properly sized crude ore into a gas- or oil-fired furnace
with the temperature above 760°c <1,400°F). The desired
temperature is the point at which the specific perlite being
processed begins to soften to a plastic state and allows the
entrapped water to be released as steam. This rapidly
expands the perlite particles. Horizontal rotary and
vertical furnaces are commonly used for expanding perlite.
In either case, there is no process water involved.
Horizontal rotary furnaces occasionally require non-contact
cooling water for bearings.
Raw Waste Load
Waste is generated both in the mining and processing
processes. In the mining of perlite, oversize materials too
large for the primary crushers are discarded. In the
processing process fines are generated from screening
operations and airborne dust and fines are collected in
baghouses. The nature and amounts of raw wastes generated
are as follows:
133
-------
VENT
BAG
HOUSE
QUARRY
CRUSHING
DRYING
OJ
SCREENING
PRODUCT
EXPANDING
XPANDED
PRODUCT
DUST WASTE
FINES FINES
TO TO
LAND LAND
DISPOSAL DISPOSAL
FIGURE 30
PERLITE M!N!NG AND PROCESSING
-------
kg/kkg product:
facility Waste Material (lb/1000mlb^
5501 dust and fines 150-200
5502 large boulders 250
fines
5503 large boulders ,10
fines 50
The wasted material represents approximately 10-25 percent
loss of material in these mining and processing operations.
Water Use
There is currently no water used in the mining or processing
operations. Facility 5500 does dewater the quarry when
water accumulates, but this water is pumped out and
evaporated on land.
Waste water Treatment
Since there is no water used, there is no waste water
generated or water treatment required.
Effluent and Disposal
There are no effluents from these operations. The oversize
materials, processing and baghouse fines are hauled to the
mine areas and land-disposed. There is work being done by
facilities 5501 and 5503 to reclaim further product grades
from the waste fines. Facility 5501 is investigating the
idea of a facility fines disposal process using water to
make pellets designed to make land-disposal of fines easier
and more efficient.
135
-------
PUMICE
Process Description
Pumice is surface mined in open pit operations. The
material is then crushed, screened, and shipped for use as
either aggregate, cleaning powder or abrasive. A process
flowsheet is given in Figure 31.
Raw waste Load
At most facilities, there are no waterborne wastes as no
water is employed. At some facilities, there are some solid
wastes consisting of overburden and oversize materials
(facility 5665 0.5 kg/kkg, facility 5669 37.5-151 kg/kkg).
These are disposed of as landfill in mined out areas. Only
one facility, facility 1705, has an effluent and this
consists of waters from a wet scrubber used for dust
control.
Water Use
At most operations, no water at all is employed. This is
true for facilities 1702, 1703, 1704, 5665, 5667 and 5669.
At facility 1701 a small amount of water (10.55 1/kkg
product) is used for dust control purposes and this is
absorbed by the product and not di scharged * At
facility 1705 a wet scrubber is used for dust control
purposes.
Waste water Treatment
At all facilities except facility 1705, there is no waste
water to be treated. At facility 1705, the scrubber water
is discharged to a settling pond for removal of suspended
materials prior to final discharge.
Effluent and Disposal
There is no effluent at any of the facilities except
facility 1705. Facility 1705 operates on an intermittent
basis, and no information is available on the composition of
its discharge. This facility produces less than 0.1 percent
of U.S. pumice.
VERMICULITE
Process Description
Mining of vermiculite at facility 5506 is conducted by bench
quarrying using power shovels and loaders. Occasionally,
blasting is necessary to break up irregularly occurring
136
-------
SURFACE
MINING
SCREENING
AND
CRUSHING
PRODUCT
FIGURE .31
PUMICE MINING AND PROCESSING
-------
L
dikes of syenite. Trucks then haul the ore to the process
facility. The vermiculite is concentrated by a series of
operations based on mechanical screening and flotation, a
new process replacing one more dependent on mechanical
separations. Sizer screens split the raw ore into coarse
and fine fractions. The fines are washed, screened, and
floated. After another screening the product is dewatered,
dried and sent to the screening facility at another
location.
The coarse fraction is re-screened and the fines from this
screening are hydraulically classified. Coarse fractions
from screening and classification are sent to a wet
rod-processing operation and recycled. The coarsest
fraction from the hydraulic classification is sent to coarse
tails. The fines from hydraulic classification are
screened, floated, re-*screened and sent to join the other
process stream at the dewatering stage.
Mining of vermiculite at facility 5507 is conducted by open
pit mining using scrapers and bulldozers to strip off
overburden. The ore is then hauled to the facility on dump
trailer-tractor haul units. The overburden and sidewall
waste is returned to the mine pit when it is reclaimed. The
vermiculite ore is fed into the process facility where it is
ground and deslimed. The vermiculite is then sent to
flotation. After flotation, the product is dried, screened,
and sent to storage for eventual shipping. Figure 32 is a
flow diagram showing the mining and processing of
vermiculite.
Raw waste Loads
At facility 5506 waste is generated from the two thickening
operations, from boiler water bleed, and from the washdown
stream that is applied at the coarse tails-solids discharge
point. (This is used to avoid pumping a wet slurry of
highly abrasive pyroxenite coarse solids.)
At facility 5507, there is one waste stream coming from the
mill generated from desliming, flotation and drying
operations. This stream consists of mineral and earth
solids, principally silicates including actinolite,
feldspar, quartz, and minor amounts of tremolite, talc, and
magnetite (1,600 kg/kkg product).
Water Use
Water comes from surface springs and runoff to facility 5507
vermiculite operations both as source and make-up water. At
facility 5506, water from 2 local creeks provides both
source and make-up water for the vermiculite operations. In
138
-------
VENT
VD
OPEN
PIT
MINE
unnijiimggg
MAKE-UP WATER <>
GRIND,
WASH
AND
SCREEN
j J
ILII immig£l£
I
RECYCLE
FLOTATION
i
1
•
MMIIIU^P
t
RECYCLE
1
DRY
J
f
SCREEN
\
RECYCLE
PONDS
•PRODUCT
FIGURE 32
VERMiCULITE. MININI3 AND PROCESSING
-------
dry weather a nearby river becomes the make-up water source
A well on the property provides sanitary and boiler water.
Consumption of water for the two facilities is as follows;
Facility
5507
Consumption
process
dust control
evaporation
from drying
total
consumed
recycle
net make-up
1/kkq product
46,400
2,500
83
48,900
48,820
83
(qal/ton)
(11,110)
(600)
(20)
(11,720)
(11,700)
(20)
water
Since the only water loss is through evaporation during
drying operations and some unknown amount is lost through
seepage from the ponds to ground water, the net amount of
make-up water reflects this loss.
Facility
5506
Consumption
process
boiler
non-contact
cooling
total
consumed
recycle
apparent
1/kkq
5,430
120
740
6,290
4,820
1,480
(qal/ton)
(1*580)
(40)
(220)
(1,840)
dr400)
(430)
water loss
net make-up 1,480 (430)
water
There is some water loss from the facility operation but no
indication was given as to where the loss occurred, possibly
boiler blowdown, product drying, or pond seepage.
140
-------
Waste water Treatment
Both vermiculite operations have no discharge of wa ste
waters. At facility 5506, the waste stream is pumped to a
series of three settling ponds in which the solids are
impounded, the water is clarified using aluminum sulfate as
a flocculant, and the clear water is recycled to the process
facility. The only water escape from this operation is due
to evaporation and seepage from the pond into ground water.
The overburden and sidewall waste is returned to the mine
upon reclamation
At facility 5507, the waste streams are pumped to a tailings
pond for settling of solids from which the clear water
underflows by seepage to a "process facility pond" which
serves as a reservoir for process water to the process
facility. Local lumbering operations are capable of
drastically altering water runoff in the watersheds around
the mine. This requires by-pass streams around the ponding
system.
Effluents and Disposal
Solid mineral wastes are land-disposed at both vermiculite
operations. Both sites have no effluent as all water
(excepting loss due to evaporation and seepage to ground
water) is recycled to the process.
The recycled process water amounting to 10,200 1/min
(2,700 gal/min) at facility 5507 has the following
concentration of constituents (mg/1):
Acidity 6.U8
Total solids 110
Total volatile 22
solids
Alkalinity As 0
CaC03
Hardness As 49.4
CaC03
Fe 0.01
Mn nil
141
-------
MICA AND SERICITE (SIC 1499)
Mica and sericite are mined in open pits using conventional
surface mining techniques. The crude ore from .these mines
is generally hauled to stockpiles at mills for processing.
Sixteen significant U.S. facilities producing flake, scrap
or ground mica were identified in this study. Six of these
facilities are dry grinding facilities processing either
mica obtained from company-owned mines or purchased mica
from an outside supplier, three facilities are wet grinding
facilities and seven are wet mica beneficiation facilities
utilizing froth flotation and/or spirals, hydroclassifiers
and wet screening techniques to recover mica.
Additionally there are four known sericite producers in the
U.S. Three of these companies surface mine the crude ore
for brick facilities and a fourth company has a dry grinding
facility and sells the sericite after processing.
DRY GRINDING OF MICA AND SERICITE
Dry grinding facilities are of two types, those which
process ore obtained directly from the mine and others which
process beneficiated scrap and flake mica. A generalized
flow diagram for these facilities are given in Figure 33.
The ore from the mine is processed through coarse and fine
screens before processing. The wastes generated from the
two screening operations consist of rocks, boulders, etc.,
which are bulldozed into stockpiles. The crude ore is next
fragmented, dried and sent to a hammerprocess facility. In
those facilities which process scrap and flake mica, the
feed is sent directly into the hammerprocess facility or
into a pulverizer. In both types of facilities, the milled
product is passed through a series of vibrating screens to
separate various sizes of product for bagging. The waste
material from the screening operations consists of quartz
and schist pebbles.
In some facilities either the screened ore or the scrap and
flake mica is processed in a fluid energy process facility.
The ground product, in these facilities, is next classified
in a closed circuit air classifier to yield various grades
of products. Dry grinding facilities utilize baghouse
collectors for air pollution control. The dust is reclaimed
from these collectors and marketed. Proce'ss water is not
used in dry grinding facilities, therefore, during normal
operating conditions, waterborne pollutants are not
generated by these facilities.
142
-------
BAG
HOUSE
FLAKE AND
SCRAP MICA
MINE
•«»
SCREEN
AND
STORE
u>
LEGEND;
.SCRAP AND FLAKE MICA
PRODUCT
—^PRODUCT
^PRODUCT
——-^PRODUCT
WASTE
FIGURE .33
MICA MINING AND PROCESSING
(DRY)
-------
Even though these facilities do not use process water,
natural drainage at the mine and process facility could
carry fines from the stockpiles to a considerable distance,
during and after heavy rainfall.
WET GRINDING OF MICA AND SERICITE
Process Description
In a typical wet grinding facility, scrap and flake mica is
batch milled in a water slurry. The mica rich concentrate
from the process facility is decanted, dried, screened, and
then bagged. The mica product from these facilities is
primarily used by the paint, rubber, and plastic industries.
The tailings from the process facility are dewatered to
remove the sand. The effluents emanating from the decanting
and dewatering operations constitute the waste stream from
the facility. A generalized flow diagram for wet grinding
operations is shown in Figure 34.
At one facility visited the scrap and flake mica is
processed in a fluid energy process facility using steam.
The steam generated in boilers is used in process and vented
to the atmosphere. The waste streams emanating from the
boiler operations are sludge generated from the conventional
water softening process, filter backwash, and boiler
blowdown wastes.
Raw Waste Loads
The raw waste loads for facilities 2055 and 2059 are given
below:
kQ/kkq of product {lb/1000 Ib)
2055 2059
clays 100 50
and sands
Water Use
Facilities 2059 and 2055 consume water at 4,900 and 12,500
1/kkg product (1,300 and 3,000 gal/ton), respectively. At
facility 2055, about 80 percent of the water used in the
process is make-up water, the remainder is recycled water
from the decanting and dewatering operations. At facility
2059 makeup water consumed is 1,500 1/kkg of product
(360 gallons/ton); the remainder is recycled from the
settling pond. The hydraulic loads of these facilities are
given below:
144
-------
WATER
SCRAP MICA—«DI
WATER
WATER
GRINDING
MILLS
BHBX&g,
RIFFLE
LAUNDER
»
•
SAND
RLE
l»T««lJj|p
DECANT
TANK
m LUII jgp
CENTRIFUGE
f \
F 1
SETTLING
TANKS
FEED
BIN
amfi0)
DRYER
^ MICA
^ PRODUCT
TO
DISPOSAL
POND
WATER RECYCLED
TO GRINDING MILLS
FIGURE 34
MINING AND PROCESSING
(
WE"
-------
1/kkq of product: (gal/ton)
2055 2059
Make-up water 10,000 2,200
(2,400) (530)
Recycled water 2r500 4,200
(600) (1,000)
Boiler feed unknown 1,100
(260)
Total Process 12,500 5,400
Water (3,000) (1,300)
Waste Treatment
At facility 2055, the raw waste stream is collected in surge
tanks and about 20 percent of the decanted water is recycled
to the process. The remainder is pumped to a nearby
facility for treatment. The treatment consists of adding
polymer, clarification and filtration. The filter cake is
stockpiled and the filtrate discharged.
At facility 2059, the waste stream flows to settling tanks.
The underflow from the settling tanks is sent back to the
process for mica recovery. The overflow goes into a
0.8 hectare (2 acre) pond for settling. The decanted water
from this pond is recycled to the process.
Effluent Composition
The effluent from facility 2055 is treated and discharged by
a neighboring company. Facility 2059 has no discharge under
normal operating conditions. However, during heavy
rainfall, the settling pond overflows and the effluent is
discharged.
WET BENEFICIATION PROCESS OF MICA AND SERICITE
Process Description
These ores contain approximately 5 to 15 percent mica. At
the beneficiation facility, the soft weathered material from
the stockpiles is hydraulically sluiced into the processing
units. The recovery of mica from the ore requires two major
steps, first, the coarse flakes are recovered by spirals
and/or trommel screens and second, fine mica is recovered by
froth flotation.
146
-------
Five of the seven facilities discussed below use a
combination of spiral classifiers and flotation techniques
and the remaining two facilities use only spirals to recover
the mica from the crude ore. Beneficiation includes
crushing, screening, classification, and processing. The
larger mica flakes are then separated from the waste sands
in spiral classifiers. The fine sand and clays are
deslimed, conditioned and sent to the flotation section for
mica recovery. In facilities using only spirals, the
underflow is screened to recover flaked mica. In both types
of facilities, the mica concentrate or the flake mica is
centrifuged, dried, and ground.
Although all flotation facilities use the same general
processing steps, in some facilities, tailings are processed
to recover additional by-products. Facility 2050 processes
the classifier waste stream to produce clays for use by the
brick industry and also processes the mica flotation
tailings to recover feldspar. Facilities 2052 and 2057
process the classifier waste to recover a high grade clay
for use by the ceramic industry. Generalized flow diagrams
for facilities using a combination of spirals and flotation
and for facilities using spirals only is given in Figure 35.
Raw Waste Loads
The raw waste load in these facilities consists of mill
tailings, thickener overflow, and wastes from the various
dewatering units. In some facilities, waste water from wet
scrubbing operations is used for dust control purposes. The
raw waste loads for these facilities are given as follows:
Clay, slimes, mica fines and sand wastes
kg/kkg of product^ (lb/1000 Ibj
600
14,400
2,600
4,000
4,700
2,900
6,300
147
-------
WATER
MINE
*»
•P-
oo
LEGEND;
SPIRAL
CRUSH,
SCREEN
AND
CLASSIFY
1
CYCLONE
TION
L
MILL
SPIRALS
AND/OR
CYCLONES
1
i
L
V,
SCREEf
ATER R
1
FLOTAT
i
SAND PILE
1
i
POND
REAGENTS
CENTRIFUGE
DRY
AND
GRIND
PRODUCT
FIGURE .35
MICA MINING AND PROCESSING
(FLOTATION OR SPIRAL SEPARATION)
-------
Water Use
The water used in these facilities is dependent upon the
quantity and type of clay material in the crude ore. These
facilities consume water at 69,500 to 656,000 1/kkg (16,700
to 157,000 gal/ton) of product. The hydraulic loads of
these facilities are summarized as follows:
Process Water Used
Facility
2050
2051
2052
2053
2054
2057
2058
1/kkg of product (gal/ton)
95,200
240,000
125,000
110,000
69,500
143,000
656,000
(22,800)
(57,600)
(30,000)
(26,400)
(16,700)
(34,000)
(157,000)
Other Water Consumption
Facility
i/EKa of product
process discharge
(gal/ton)
loss due evaporation,
percolation and
spills
2050
2051
2052
2053
2054
2057
2058
none
none
75,200 (18,000)
none
69,500 (16,700)
86,000 (20,600)
none
negligible
negligible
50,600 (12,100)
80 (20)
57,000 (13,700)
Waste Treatment
In facilities 2050, 2051, 2053, and 2058, the wastes are
treated by settling in ponds and the supernatant from the
last pond is recycled to the facility. The sizes of the
ponds used at each facility are given below.
149
-------
Facility hectares (acres)
2050 7.3 (18)
2051 3.2 (8)
2053 0.8, 1.6, (2, 4, 7)
2.8
2058 8.1 (20)
During normal operating procedures, there is no discharge
from ponds 2050 and 2051. However, these ponds discharge
during exceptionally heavy rainfalls (4" rain/24 hours) ,
The only discharge at facility 2058 is the drainage from the
sand stockpiles which flows into a 0.4 hectare (1-acre) pond.
which discharges.
At facility 2054 waste water is treated in a 1.2 hectare
(3-acre) pond. The effluent from this pond is discharged.
This facility has suspended its operation since June, 1974,
due to necessary repairs to the pond, and plans to convert
the water flow system of this operation to a closed circuit
"no discharge" process by the addition of thickening and
filtration equipment.
At facilities 2052 and 2057 the waste water is treated in a
series of ponds and the overflow from the last pond is
treated by lime for pH adjustment prior to discharge.
Facility 2052 has three ponds of 1.2, 1.6, and 3.6 hectares
(3, 4, and 9 acres, respectively) in size. In addition to
mica, these two facilities produce clay for use by ceramic
industries. According to responsible company officials,
these two facilities cannot operate on a total water recycle
basis. The amine reagent used in flotation circuits is
detrimental to the clay products as it affects their
viscosity and plasticity.
Effluent Composition
The significant constituents in the effluent from these
facilities are given below:
facility 2052 2054 2057
pH before lime
treatment 4,2 4.3
pH after lime treatment 6,5 6-9 6.5
TSS, mg/1 20 400 <15
settleable solids,
ml/liter <0.1 <0.1 <0.1
There is no quantitative data available on the discharge
from facility 2058.
150
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
INTRODUCTION
The waste water constituents of pollution significance for
this segment of the mineral mining and processing industry
are based upon those parameters which have been identified
in the untreated wastes from each subcategory of this study.
The waste water constituents are further divided into those
that have been selected as pollutants of significance with
the rationale for their selection, and those that are not
deemed significant with the rationale for their rejection.
The basis for selection of the significant pollutant para-
meters was:
(1) toxicity to terrestrial and aquatic organisms;
(2) substances causing dissolved oxygen depletion in
streams;
(3) soluble constituents that result in undesirable tastes
and odors in water supplies;
(4) substances that result in eutrophication and stimulate
undesirable algal growth;
(5) substances that produce unsightly conditions in
receiving water; and
(6) substances that result in sludge deposits in streams.
SIGNIFICANCE AND RATIONALE FOR SELECTION OF POLLUTION
PARAMETERS
Biochemical Oxygen Demand (BOD)
Biochemical oxygen demand (BOD) is a measure of the oxygen
consuming capabilities of organic matter. The BOD does not
in itself cause direct harm to a water system, but it does
exert an indirect effect by depressing the oxygen content of
the water. Sewage and other organic effluents during their
processes of decomposition exert a BOD, which can have a
catastrophic effect on the ecosystem by depleting the oxygen
supply. Conditions are reached frequently where all of the
oxygen is used and the continuing decay process causes the
production of noxious gases such as hydrogen sulfide and
methane. Water with a high BOD indicates the presence of
decomposing organic matter and subsequent high bacterial
counts that degrade its quality and potential uses.
151
-------
Dissolved oxygen (DO) is a water quality constituent that,
in appropriate concentrations, is essential not only to keep
organisms living but also to sustain species reproduction,
vigor, and the development of populations. Organisms
undergo stress at reduced DO concentrations that make them
less competitive and less able to sustain their species
within the aquatic environment. For example, reduced DO
concentrations have been shown to interfere with fish
population through delayed hatching of eggs, reduced size
and vigor of embryos, production of deformities in young,
interference with food digestion, acceleration of blood
clotting, decreased tolerance to certain toxicants, reduced
food efficiency and growth rate, and reduced maximum
sustained swimming speed. Fish food organisms are likewise
affected adversely in conditions with suppressed DO. Since
all aerobic aquatic organisms need a certain amount of
oxygen, the consequences of total lack of dissolved oxygen
due to a high BOD can kill all inhabitants of the affected
area.
If a high BOD is present, the quality of the water is
usually visually degraded by the presence of decomposing
materials and alga blooms due to the uptake of degraded
materials that form the food stuffs of the algal
populations. BOD was not a major contribution to pollution
in this industry, but may possibly exist because of the use
of organic flotation agents.
Fluorides
As the most reactive non-metal, fluorine is never found free
in nature but as a constituent of fluorite or fluorspar,
calcium fluoride, in sedimentary rocks and also of cryolite,
sodium aluminum fluoride, in igneous rocks. Owing to their
origin only in certain types of rocks and only in a few
regions, fluorides in high concentrations are not a common
constituent of natural surface waters, but they may occur in
detrimental concentrations in ground waters.
Fluorides are used as insecticides, for disinfecting brewery
apparatus, as a flux in the manufacture of steel, for
preserving wood and mucilages, for the manufacture of glass
and enamels, in chemical industries, for water treatment,
and for other uses.
Fluorides in sufficient quantity are toxic to humans, with
doses of 250 to 450 mg giving severe symptoms or causing
death.
There are numerous articles describing the effects of
fluoride-bearing waters on dental enamel of children; these
studies lead to the generalization that water containing
152
-------
less than 0.9 to 1.0 mg/1 of fluoride will seldom cause
mottled enamel in children, and for adults, concentrations
less than 3 or 4 mg/1 are not likely to cause endemic
cumulative fluorosis and skeletal effects. Abundant
literature is also available describing the advantages of
maintaining 0.8 to 1.5 mg/1 of fluoride ion in drinking
water to aid in the reduction of dental decay, especially
among children.
Chronic fluoride poisoning of livestock has been observed in
areas where water contained 10 to 15 mg/1 fluoride.
Concentrations of 30-50 mg/1 of fluoride in the total ration
of dairy cows is considered the upper safe limit. Fluoride
from waters apparently does not accumulate in soft tissue to
a significant degree and it is transferred to a very small
extent into the milk and to a somewhat greater degree into
eggs. Data for fresh water indicate that fluorides are
toxic to fish at concentrations higher than 1.5 mg/1.
Fluoride is found in one industry sutcategory in this
segment, the mining and processing of industrial sand by the
HF flotation process.
Iron
Iron is considered to be a highly objectionable constituent
in public water supplies,, the permissible criterion has been
set at 0.3 mg/1.
Oil and Grease
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or
other plankton. Deposition of oil in the bottom sediments
can serve to inhibit normal benthic growths, thus
interrupting the aquatic food chain. Soluble and emulsified
material ingested by fish may taint the flavor of the fish
flesh. Water soluble components may exert toxic action on
fish. Floating oil may reduce the re-aeration of the water
surface and in conjunction with emulsified oil may interfere
with photosynthesis. Water insoluble components damage the
plumage and coats of aquatic animals and fowls. Oil and
grease in the water can result in the formation of
objectionable surface slicks preventing the full aesthetic
enjoyment of the water, oil spills can damage the surface
of boats and can destroy the aesthetic characteristics of
beaches and shorelines.
Acidity and Alkalinity
Acidity and alkalinity are reciprocal terms. Acidity is
produced by substances that yield hydrogen ions upon
hydrolysis and alkalinity is produced by substances that
153
-------
yield hydroxyl ions. The terms "total acidity" and "total
alkalinity" are often used to express the buffering capacity
of a solution. Acidity in natural waters is caused by
carbon dioxide, mineral acids, weakly dissociated acids, and
the salts of strong acids and weak bases. Alkalinity is
caused by strong bases and the salts of strong alkalies and
weak acids.
The term pH is a logarithmic expression of the concentration
of hydrogen ions. At a pH of 7, the hydrogen and hydroxyl
ion concentrations are essentially equal and the water is
neutral. Lower pH values indicate acidity while higher
values indicate alkalinity. The relationship between pH and
acidity and alkalinity is not necessarily linear or direct.
Waters with a pH below 6.0 are corrosive to water works
structures, distribution lines, and household plumbing
fixtures and can thus add such constituents to drinking
water as iron, copper, zinc, cadmium and lead. The hydrogen
ion concentration can affect the "taste" of the water. At a
low pH water tastes "sour". The bactericidal effect of
chlorine is weakened as the pH increases, and it is
advantageous to keep the pH close to 7. This is very
significant for providing safe drinking water.
Extremes of pH or rapid pH changes can exert stress
conditions or kill aquatic life outright. Dead fish,
associated algal blooms, and foul stenches are aesthetic
liabilities of any waterway. Even moderate changes from
"acceptable" criteria limits of pH are deleterious to some
species. The relative toxicity to aquatic life of many
materials is increased by changes in the water pH.
Metalocyanide complexes can increase a thousandfold in
toxicity with a drop of 1.5 pH units. The availability of
many nutrient substances varies with the alkalinity and
acidity. Ammonia is more lethal with a higher pH.
The lacrimal fluid of the human eye has a pH of
approximately 7.0 and a deviation of 0.1 pH unit from the
norm may result in eye irritation for the swimmer.
Appreciable irritation will cause severe pain.
Total Suspended Solids
Suspended solids include both organic and inorganic
materials. The anorganic components include sand, silt, and
clay. The organic fraction includes such materials as
grease, oil, tar, animal and vegetable fats, various fibers,
sawdust, hair and various materials from sewers. These
solids may settle out rapidly and bottom deposits are often
a mixture of both organic and inorganic solids. They
adversely affect fisheries by covering the bottom of the
154
-------
stream or lake with a blanket of material that destroys the
fish-food bottom fauna or the spawning ground of fish.
Deposits containing organic materials may deplete bottom
oxygen supplies and produce hydrogen sulfide, carbon
dioxide, methane, and other noxious gases.
In raw water sources for domestic use, state and regional
agencies generally specify that suspended solids in streams
shall not be present in sufficient concentration to be
objectionable or to interfere with normal treatment
processes. Suspended solids in water may interfere with
many industrial processes, and cause foaming in boilers, or
encrustations on equipment exposed to water, especially as
the temperature rises. Suspended solids are undesirable in
water for most industrial processes and power facilities.
Suspended particles also serve as a transport mechanism for
pesticides and other substances which are readily sorbed
into or onto clay particles.
Solids may be suspended in water for a time, and then settle
to the bed of the stream or lake. These settleable solids
may be inert, slowly biodegradable materials, or rapidly
decomposable substances. While in suspension, they increase
the turbidity of the water, reduce light penetration and
impair the photosynthetic activity of aquatic facilities.
Solids in suspension are aesthetically displeasing. When
they settle to form sludge deposits on the stream or lake
bed, they are often much more damaging to the life in water,
and they retain the capacity to displease the senses.
Solids, when transformed to sludge deposits, may do a
variety of damaging things, including blanketing the stream
or lake bed and thereby destroying the living spaces for
those benthic organisms that would otherwise occupy the
habitat. When of an organic and therefore decomposable
nature, solids use a portion or all of the dissolved oxygen
available in the area. Organic materials also serve as a
seemingly inexhaustible food source for sludgeworms and
associated organisms.
Turbidity is principally a measure of the light absorbing
properties of suspended solids. It is frequently used as a
substitute method of quickly estimating the total suspended
solids when the concentration is relatively low. Total
suspended solids are the single most important pollutant
parameter found in this segment of the mineral mining and
processing industry.
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Asbestos
"Asbestos" is a generic term for a number of fire-resistant
hydrated silicates that, when crushed or processed, separate
into flexible fibers made up of fibrils noted for their
great tensile strength. Although there are many asbestos
minerals, only five are of commercial importance:
chrysotile, a tubular serpentine mineral, accounts for
95 percent of the world's production; the others, all
amphiboles, are amosite, crocidolite, anthophyllite, and
tremolite. The asbestos minerals differ in their metallic
elemental content, range of fiber diameters, flexibility or
hardness, tensile strength, surface properties, and other
attributes that determine their industrial uses and may
affect their respirability, deposition, retention,
translocation, and biologic reactivity.
Serpentine asbestos is a magnesium silicate the fibers of
which are strong and flexible so that spinning is possible
with the longer fibers. Amphibole asbestos includes various
silicates of magnesium, iron, calcium, and sodium. The
fibers are generally brittle and cannot be spun but are more
resistant to chemicals and to heat than serpentine asbestos.
Chrysoltile 3MgO*2SiO2«2H20
Anthophyllite (FeMg)«Sio3«H2o
Amosite (ferroanthophyllite)
Crocidolite NaFe»(SiO3)2«FeSiO3«H2O
Tremolite Ca2Mg5Si8O22(OH) 2
All epidemiclogic studies that appear to indicate
differences in pathogenicity among types of asbestos are
flawed by their lack of quantitative data on cumulative
exposures, fiber characteristics, and the presence of
cofactors. The different types, therefore, cannot be graded
as to relative risk with respect to asbestosis. Fiber size
is critically important in determining respirability,
deposition, retention, and clearance from the pulmonary
tract and is probably an important determinant of the site
and nature of biologic action. Little is known about the
movement of the fibers within the human body, including
their potential for entry through the gastrointestinal
tract. There is evidence though that bundles of fibrils may
be broken down within the body to individual fibrils.
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SIGNIFICANCE AND RATIONALE FOR REJECTION OF POLLUTION
PARAMETERS
A number of pollution parameters besides those selected were
considered, but had to be rejected for one or several of the
following reasons:
/
(1) insufficient data on facility effluents;
(2) not usually present in quantities sufficient to cause
water quality degradation;
(3) treatment does not "practicably" reduce the parameter;
and
(4) simultaneous reduction is achieved with another
parameter which is limited.
Toxic Materials
Although arsenic, antimony, barium, boron, cadmium,
chromium, copper, cyanide ion, manganese, mercury, nickel,
lead, selenium, tin, and zinc are harmful pollutants, they
were not found to be present in quantities sufficient to
cause water quality degradation.
Dissolved Solids
The total dissolved solids is a gross measure of the amount
of soluble pollutants in the waste water. It is an
important parameter in drinking water supplies and water
used for irrigation. A total dissolved solids content of
less than 500 mg/1 is considered desirable. From the
standpoint of quantity discharged, TDS could have been
considered a harmful characteristic. However, energy
requirements, especially for evaporation, and solid waste
disposal costs are usually so high as to preclude limiting
dissolved solids at this time. The cations A1+3, Ca*2,
Mg+2, K+ and Na+, the anion Cl~ and the radical groups
C03~z, N02~, phosphates and silicates are commonly found in
all nautral water bodies. Process water, mine water and
storm runoff will accumulate quantities of the above
constutuents both in the form of suspended and dissolved
solids. However, their amount is small and certainly not
enough to cause water quality problems. Limiting suspended
solids and dissolved solids, where they pose a problem, is a
more practicable approach to limiting these ions.
Temperature
Temperature is one of the most important and influential
water quality characteristics. Temperature determines those
species that may be present; it activates the hatching of
young, regulates their activity, and stimulates or
suppresses their growth and development; it attracts, and
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may Jcill when -the water becomes too hot or becomes chilled
too suddenly. Colder water generally suppresses
development. Warmer water generally accelerates activity
and may be a primary cause of aquatic facility nuisances
when other environmental factors are suitable.
Temperature is a prime regulator of natural processes within
the water environment. It governs physiological functions
in organisms and, acting directly or indirectly in
combination with other water quality constituentsr it
affects aquatic life with each change. These effects
include chemical reaction rates, enzymatic functions,
molecular movements, and molecular exchanges between
membranes within and between the physiological systems and
the organs of an animal.
Chemical reaction rates vary with temperature and generally
increase as the temperature is increased. The solubility of
gases in water varies with temperature. Dissolved oxygen is
decreased by the decay or decomposition of dissolved organic
substances and the decay rate increases as the temperature
of the water increases reaching a maximum at about 30°C
(86 ° F). The temperature of stream water, even during
summer, is below the optimum for pollution-associated
bacteria. Increasing the water temperature increases the
bacterial multiplication rate when the environment is
favorable and the food supply is abundant.
Reproduction cycles may be changed significantly by
increased temperature because this function takes place
under restricted temperature ranges. Spawning may not occur
at all because temperatures are too high. Thus, a fish
population may exist in a heated area only by continued
immigration. Disregarding the decreased reproductive
potential, water temperatures need not reach lethal levels
to decimate a species. Temperatures that favor competitors,
predators, parasites, and disease can destroy a species at
levels far below those that are lethal.
Fish food organisms are altered severely when temperatures
approach or exceed 90°F, Predominant algal species change,
primary production is decreased, and bottom associated
organisms may be depleted or altered drastically in numbers
and distribution. Increased water temperatures may cause
aquatic facility nuisances when other environmental factors
are favorable.
Synergistic actions of pollutants are more severe at higher
water temperatures. Given amounts of domestic sewage,
refinery wastes, oils, tars, insecticides, detergents, and
fertilizers more rapidly deplete oxygen in water at higher
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temperatures, and the respective toxicities are likewise
increased.
When water temperatures increase, the predominant algal
species may change from diatoms to green algae, and finally
at high temperatures to blue-green algae, because of species
temperature preferentials. Blue-green algae can cause
serious odor problems. The number and distribution of
benthic organisms decreases as water temperatures increase
above 90°F, which is close to the tolerance limit for the
population. This could seriously affect certain fish that
depend on benthic organisms as a food source.
The cost of fish being attracted to' heated water in winter
months may be considerable, due to fish mortalities that may
result when the fish return to the cooler water.
Rising temperatures stimulate the decomposition of sludge,
formation of sludge gas, multiplication of saprophytic
bacteria and fungi (particularly in the presence of organic
wastes) , and the consumption of oxygen by putrefactive
processes, thus affecting the esthetic value of a water
course.
In general, marine water temperatures do not change as
rapidly or range as widely as those of freshwaters. Marine
and estuarine fishes, therefore, are less tolerant of
temperature variation. Although this limited tolerance is
greater in estuarine than in open water marine species,
temperature changes are more important to those fishes in
estuaries and bays than to those in open marine areas,
because of the nursery and replenishment functions of the
estuary that can be adversely affected by extreme
temperature changes.
Excess thermal load, even in non-contact cooling water, has
not been and is not expected to be a significant problem in
this segment of the mineral mining and processing industry.
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
INTRODUCTION
Waterborne wastes from the mining of minerals for the con-
struction industry consist primarily of suspended solids.
These are usually composed of chemically inert and very
insoluble sand, clay or rock particles. Treatment
technology is well developed for removing such particles
from waste water and is readily applicable whenever space
requirements or economics do not preclude utilization.
In a few instances dissolved substances such as fluorides,
acids, alkalies, and chemical additives from ore processing
may also be involved. Where they are present, dissolved
material concentrations are usually low. Treatment
technology for the dissolved solids is also well-known, but
may often be limited by the large volumes of waste water
involved and the cost of such large scale operations.
The control and treatment of the usually simple waterborne
wastes found in the mining and processing of minerals for
the construction industry are complicated by several
factors:
(1) the large volumes of waste water involved for many of
the processing operations,
(2) variable waste water amount and composition from day to
day, as influenced by rainfall and other surface and
underground water contributions,
(3) differences in waste water compositions arising from ore
or raw material variability,
(4) geographical location: e.g., waste water can be handled
differently in dry isolated locations than in
industrialized wet climates.
Each of these points are discussed in the following
sections. •
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PROBLEM POLLUTANTS
Two significant was-te water problem areas have been found in
this industry:
(1) High suspended solids levels in discharged waste water
resulting from submicron suspensions which are difficult
to settle. This problem is encountered in several
segments of this industry.
(2) In at least one subcategory of this industry problems
are encountered with waterborne fluoride wastes.
Suspended solids come from mine drainage, rainwater runoff,
air pollution scrubber water, and process water. Massive
quantities of process water are used in the sand and gravel,
crushed stone, industrial sand, and mica industries. Much
of this process water, used for classifying and benefi-
ciating operations may be recycled with relatively high
suspended solids concentrations, often 200 mg/1. This makes
recycling process water not only feasible but also
economical since treatment facility demands are not as great
for water of this quality. However, in some cases, where
flotation is employed, sensitivity of the process to the
flotation reagents added makes complete recycle of process
water unfeasible, giving rise to effluents. This occurs in
some industrial sand and mica operations.
In other operations which use no process water or whose
process water volume is small, scrubber water, mine
drainage, and rainwater runoff are the major sources of
suspended solids. Dimension stone, gypsum, asbestos, and
gilsonite are examples of such industries. Asbestos
presents a special suspended solids problem in its mine
drainage due to the presence of asbestos fibers,
One of the industrial sand subcategories uses a process
employing hydrofluoric acid as a flotation reagent. This
gives rise to an acidic fluoride bearing waste water stream
which must be treated.
CONTROL PRACTICES
Control practices such as selection of raw materials, good
housekeeping, minimizing leaks and spills, in-process
changes, and segregation of process waste water streams are
not as important in the mining of minerals for the construc-
tion industry as they are in more process-oriented manufac-
turing operations. Raw materials are fixed by the
composition of the ore available; good housekeeping and
small leaks and spills have little influence on the waste
loads; and it is rare that any noncontact water, such as
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cooling water, is involved in minerals mining and
processing.
There are a number of areas, however, where control is very
important. These include:
(1) waste water containment
(2) separation and control of mine water, process water, and
rain water
(3) monitoring of waste streams.
Containment
The majority of waste water treatment and control facilities
in the mining of minerals for the construction industry use
one or more settling ponds. Often the word "pond" is an
euphemism for swamp, gully, or other low spot which will
collect water. In times of heavy rainfall these "ponds" are
often flooded and the settled solids may be swept along as
well. In many other cases, the identity of the pond may be
maintained during rainfall but its function as a settling
pond is significantly impaired by the large amount of water
flowing through it. In addition to rainfall and flooding
conditions, waste containment in ponds can be troubled with
seepage through the ground around and beneath the pond,
escape through pot holes, faults and fissures below the
water surface and physical failure of pond dams and dikes.
In most instances satisfactory pond performance can be
achieved by proper design. In instances where it is not
possible to achieve satisfactory pond performance,
alternative treatment methods can be utilized: thickeners,
clarifiers, tube and lamella separators, filters,
hydrocyclones, and centrifuges.
Separation and Control of Waste water
In these industries waste water may be separated into dif-
ferent categories:
(1) Mine drainage water. Since minerals mining operations
often involve large surface areas, the rain water that
falls on the mine or mine property surface constitutes a
major portion of the overall waste water load leaving
the property. This runoff entrains minerals, silt,
sand, clay, organic matter and other suspended solids.
(2) Process water. This is water involved in transporting,
classifying, washing, beneficiating, and separating ores
and other mined materials. When present in minerals
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mining operations this water usually contains heavy
loads of suspended solids and possibly some dissolved
materials.
The relative amounts and compositions of the above waste
water streams differ from one mining category to another and
the separation, control and treatment techniques differ for
each.
Process water is normally controlled and contained by
pumping or gravity flow through pipes, channels, ditches and
ponds. Mine drainage, on the other hand, is often
uncontrolled and may either contaminate process and mine
drainage water or flow off the land independently as non-
point discharges. Mine drainage also increases suspended
solid material in rivers, streams, creeks or other surface
water used for process water supply or, in some cases, as
point discharge sources from mining property.
Control technology, as discussed in this report, includes
techniques and practices employed before, during, and after
the actual mining or processing operation to reduce or
eliminate adverse environmental effects resulting from the
discharge of mine or process facility waste water.
Effective pollution-control planning can reduce pollutant
contributions from active mining and processing sites and
can also minimize post-operational pollution potential.
Because pollution potential may not cease with closure of a
mine or process facility, 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 processing 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.
Several techniques have been implemented to reduce
environmental degradation during strip-mining operations.
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Utilization of the box-cut technique in moderate- and
shallow-slope contour mining has increased recently because
more stringent environmental controls are being implemented.
A box cut is simply a contour strip mine in which a low-wall
barrier is maintained. Spoil may be piled on the low wall
side. This technique significantly reduces the amount of
water discharged from a pit area, since that water is
prevented from seeping through spoil banks. The problems of
preventing slides, spoil erosion, and resulting stream
sedimentation are still present, however.
Block-cut mining was developed to facilitate regrading,
minimize overburden handling, and contain spoil within
mining areas. In block-cut mining, contour stripping is
typically accomplished by throwing spoil from the bench onto
downslope areas. This downslope material can slump or
rapidly erode and must be moved upslope to the mine site if
contour regrading is desired. The land area affected by
contour strip mining is substantially larger than the area
from which the ores are extracted. When using block-cut
mining, only material from the first cut is deposited in
adjacent low areas. Remaining spoil is then placed in mined
portions of the bench. Spoil handling is restricted to the
actual pit area for all areas but the first cut, which
significantly reduces the area disturbed,
Pollution-control technology in underground mining is
largely restricted to at-source methods of reducing water
influx into mine workings. 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 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.
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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 of 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 waste water 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.
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
smaller 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
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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 rock (inclination of the rock
to the horizontal) and pumping out the water which collects
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-water Control
Pollution-control technology related to mining areas, ore
beneficiation facilites, and waste-disposal sites is
generally designed for prevention of pollution of surface
waters (i.e., streams, impoundments, and surface runoff).
Prior planning for waste disposal is a prime control method.
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.
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(2) Compaction of waste material to reduce
infiltration,
(3) Maintenance of uniformly sized refuse to enhance
good compaction (which may require additional
crushing).
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.
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 process facility process waste water. 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
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flow is the only factor preventing attainment of zero
discharge. Diversion of natural runoff from 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 Process Facility
Waste Waters ""*
A widely adopted control practice in the ore mining and
dressing industry is the use of mine water as a source of
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
process facility-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 waste water treated in the process
facility 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
waste water treatment for mines and process facilities must
be made on an individual basis, taking into account the
character of the waste water to be treated (at both the mine
and the process facility) , the water balance in the
mine/process facility 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.
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Regrading
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
(4) burying pollution-forming materials, e.g.
heavy metals
(5) reducing erosion and subsequent
sedimentation
(6) eliminating landsliding
(7) encouraging natural drainage
(8) eliminating ponding
(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.
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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. Jn
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.
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
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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
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.
Water that reaches a mine site, such as direct rainfall, can
cause serious erosion, sedimentation, and pollution
problems. Runoff-control techniques are available to
effectively deal with this water, but these techniques may
conflict with pollution-control measures. Control of
chemical pollutants forming at a mine frequently involves
reduction of water infiltration, while runoff controls to
prevent erosion usually increase infiltration, which can
subsequently increase pollutant formation.
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.
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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.
Revegetation
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.
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.
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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
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 moisture retaining 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, demon stration, 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.
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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
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
saltation. 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
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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
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 waste water 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 waste water, drilling
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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).
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 process facility 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 full capacity or are in
the process of development to full-scale. Planning of such
operations should be undertaken with treatment and control
of waste water 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 waste water parameters are likely to
be similar. Therefore, implementation of recommended
treatment and control technologies must be accomplished.
Mine and Process Facility Closure
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
most frequently utilized in deep-mine pollution abatement
are treatment and mine sealing. Treatment technology is
well defined and is generally capable of producing
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acceptable mine effluent quality. If the mine operator
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 seepage. 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 future 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.
To accomplish the objectives of the desired reclamation
goals, it is mandatory that the surface-mine operator
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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 64 cm
(26 in.) or less, the operator's 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.
Process Facility Closure. As with closed mines, a
beneficiation facility'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. Failure of
tailing ponds can have catastrophic consequences, with
respect to both immediate safety and water quality.
To protect against catastrophic occurrences, tailing ponds
should be designed to accommodate, without overflow, an
abnormal storm which is observed every 25 years. Since no
waste water 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 process facilitys are located adjacent
to mine workings, the mines can be refilled with tailings.
Care should be f taken to minimize disruption of local
drainage and to ensure that erosion and sedimentation will
not result. Maintenance of such refuse or waste piles and
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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, the operator's
assumption of responsibility should extend for a period of
ten full years after the last year of augmented seeding,
fertilization, irrigation, or effluent treatment.
Monitoring
Since most waste water discharges from these industries
contain suspended solids as the principal pollutant, complex
water analyses are not usually required. On the other hand,
many of these industries today do little or no monitoring on
waste water discharges. In order to obtain meaningful
knowledge and control of their waste water quality, many
mines and minerals processing facilities need to institute
routine monitoring measurements of the few pertinent waste
parameters,
SUSPENDED SOLIDS REMOVAL
The treatment technologies available for removing suspended
solids from minerals mining and processing waste water are
numerous and varied, but a relatively small number are
widely used. The following shows the approximate breakdown
of usage for the various techniques:
percent of treatment
facilities
removal technique using technology
settling ponds (unlined) 95-97
settling ponds (lined) <1
chemical flocculation 2-5
(usually with ponds)
thickeners and clarifiers 2-5
hydrocyclones <1
tube and lamella settlers <1
screens <1
filters <1
centrifuges <1
Settling Ponds
As shown above, the predominant treatment technique for
removal of suspended solids involves one or more settling
ponds. Settling ponds are versatile in that they perform
several waste-oriented functions including:
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O) Solids removal. Solids settle to the bottom and the
clear water overflow is much reduced in suspended solids
content.
(2) Equalization and water storage capacity. The clear
supernatant water layer serves as a reservoir for reuse
or for controlled discharge.
(3) Solid waste storage. The settled solids are provided
with long term storage.
This versatility, ease of construction and relatively low
cost, explains the wide application of settling ponds as
compared to other technologies.
The performance of these ponds depends primarily on the
settling characteristics of the solids suspended, the flow
rate through the pond and the pond size. Settling ponds can
be used over a wide range of suspended solids levels. Often
a series of ponds is used, with the first collecting the
heavy load of easily settled material and the following ones
providing final polishing to reach a desired level.
suspended level. As the ponds fill with solids they can be
dredged to remove these solids or they may be left filled
and new ponds provided. The choice often depends on whether
land for additional new ponds is available. When suspended
solids levels are low and ponds large, settled solids build
up so slowly that neither dredging nor pond abandonment is
necessary, at least not for a period of many years.
Settling ponds used in the minerals industry range from
small pits, natural depressions and swamp areas to
engineered thousand acre structures with massive retaining
dams and legislated construction design. The performance of
these ponds can vary from excellent to poor, depending on
character of the suspended particles, and pond size and
configuration.
In general the current experience in this industry segment
with settling ponds shows reduction to 50 mg/1 or less, but
for some waste waters the discharge may still contain up to
150 mg/1 of TSS. Performance data of some settling ponds
found in the dimension stone, crushed stone, construction
sand and gravel, and industrial sand subcategories is given
in Table 12.
Eighteen of these 20 facility samples show greater than
95 percent reduction of TSS by ponding. There appear to be
no correlations within a sampled subcategory due to
differences in quality of intake water, mined product, or
processing.
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Table 12
Settling Pond Performance
Stone, Sand and Gravel Operations
TSS
Percent
Treatment
Plant
Influent Effluent Reduction
Chemical
Dimension Stone
3001 1,808
3003 3,406
3007 2,178
Crushed Stone
1001
1003
1004
1021
(2 ponds)
1039
1053
Construction
Sand and Gravel
37
34
80
1391
12,700 18
Industrial Sand
1019 2,014
1101 427
1102 2,160
D - Dredge
A - Main Plant
B - Auxiliary Plant
56
56
66
97.95
99
96.3
1017 (D)
1044
1083 (A)
1083 (B)
1129
1247 (D)
5,712
5,114
20,660
8,863
4,660
93
51
154
47
32
44
29
99.12
96.99
99.77
99.64
99.06
68.82
99.86
97.22
86.88
96.94
none
FeClS.,sodium
bicarbonate
none
1,054
7,68
5,710
7,206
772
10,013
21,760
8
8
12
28
3
14
56
99.24
99.92
99.79
99.61
99.61
99.86
99.74
none
none
none
none
none
none
none
flocculating
none
none
none
none
flocculating
agent
none
none
none
flocculating
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Laboratory settling data collected on samples of the pond
influent waste water from six of" the sand and gravel
facilities contained in the above data show that under
controlled conditions they can be settled within 24 hours to
a range of 20-450 mg/1 of suspended solids, and, with the
addition of commercial coagulant can be settled to a range
of 10-60 mg/1 in the same time period. These laboratory
data are consistent with the pond performance measured
above.
In this| segment of the mineral industry, settling is usually
a prelude to recycle of water for washing purposes. At this
point the level of suspended solids commonly viewed as
acceptable in recycled water used for construction materials
washing is 200 mg/1. Every facility in the above sample
achieved this level with values ranging from 3 to 154 mg/1.
Thus the TSS levels obtained after settling in ponds are
apparently under present practices adequate for recycling
purposes in this industry segment.
Much of the poor performance exhibited by the settling ponds
employed by: the minerals industry is due to the lack of
understating of settling techniques. This is demonstrated
by the construction of ponds without prior determination of
settling rate and detention time. In some cases series of
ponds have been claimed to demonstrate a company's
mindfullness of environmental control when in fact all the
component ponds are so poorly constructed and maintained
that they could be replaced by one pond with less surface
area than the total of the series.
The chief problems experienced by settling ponds are rapid
fill-up, insufficient retention time and the closely related
short ciruciting. The first can be avoided by constructing
a series of ponds as mentioned above. Frequent dredging of
the first if needed will reduce the need to dredge the
remaining ponds. The solution to the second involves
additional pond volume or use of flocculants. The third
problem, however, is almost always overlooked. Short
circuiting is simply the formation of currents or water
channels from pond influent to effluent whereby whole areas
of the pond are not utilized. The principles of clarifier
construction apply here. The object is to achieve a uniform
plug flow from pond influent to effluent. This can be
achieved by proper inlet-outlet construction that forces
water to be uniformly distributed at those points, such as
a weir. Frequent dreding or insertion of baffles will also
minimize channelling. The EPA report "Waste water Treatment
Studies in Aggregate and Concrete Production" (reference 25)
in detail lists the procedure one should follow in designing
and building settling ponds.
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Clarifiers and Thickeners
An alternative method of removing suspended solids is the
use of clarifiers or thickeners which are essentially tanks
with internal baffles, compartments, sweeps and other
directing and segregating mechanisms to provide efficient
concentration and removal of suspended solids in one
effluent stream and clarified liquid in the other,
Clarifiers differ from thickeners primarily in their basic
purpose. Clarifiers are used with the main purpose of
producing a clear overflow with the solids content of the
sludge underflow being of secondary importance. Thickeners,
on the other hand, have the basic purpose of producing a
high solids underflow with the character of the clarified
overflow being of secondary importance. Thickeners are also
usually smaller in size but more massively constructed for a
given throughput,
Clarifiers and thickeners have a number of distinct
advantages over ponds:
(1) Less land space is required. Since these devices are
much more efficient in settling capacity than ponds.
(2) Influences of rainfall are much less than for ponds. If
desired the clarifiers and thickeners can even be
covered.
(3) Since the external construction of clarifiers and
thickeners consist of concrete or steel tanks ground
seepage and rain water runoff influences do not exist.
On the other hand, clarifiers and thickeners suffe-r some
distinct disadvantages as compared with ponds:
(1) They have more mechanical parts and maintenance.
(2) They have only 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.
Clarifiers and thickeners are usually used when sufficient
land for ponds is not available or is very expensive.
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Hydrocy clones
While hydrocyclones are widely used in the separation, clas-
sification and recovery operations involved in minerals
processing, they are used only infrequently for waste water
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 25-50 microns. 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 can not be
removed by hydrocyclones but may be handled by ponds or
other settling technology. Also hydrocyclones are of
doubtful effectiveness when flocculating agents are used to
increase settling rates.
Hydrocyclones are used as scalping units to recover small
sand or other mineral particles in the 25 to 200 micron
range, particularly if the recovered material can be sold as
product. In this regard hydrocyclones may be considered as
converting part of the waste load to useful product as well
as providing the first step of waste water treatment. Where
land availability is a problem, a bank of hydrocyclones may
serve in place of a primary settling pond.
Tube and Lamella Settlers
Tube and lamella settlers require less land area than
clarifiers and thickeners. These compact units, which
increase gravity settling efficiency by means of closely
packed inclined tubes and plates, can be used for either
scalping or waste water polishing operations depending on
throughput and design.
Centrifuges
Centrifuges are not widely used for minerals mining waste
water treatment. Present industrial-type centrifuges are
relatively expensive and not particularly suited for this
purpose. Future use of centrifuges will depend on
regulations, land space availability and the development of
specialized units suitable for minerals mining operations.
Flocculation
Flocculating agents increase the efficiency of settling
facilities and they are of two general types: ionic and
polymeric. The ionic types such as alum, ferrous sulfate
and ferric chloride function by neutralizing the repelling
double layer ionic charges around the suspended particles.
185
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-thereby allowing the particles to attract each other and
agglomerate. Polymeric types function by physically
agglomerating the particles.
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 such scalping
treatment. Agglomeration, or flocculation, can then be
achieved with less reagent and 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 10 to 100 mg/1 concentrations in the waste
water while the higher priced polymeric types are effective
in the 2 to 20 mg/1 concentrations.
Flocculants have been used by several segments within the
minerals industry with varying degrees of success. The use
of flocculants particularly for the hard to settle solids is
more of an art than a science, since it is frequently
necessary to try several flocculants at varying
concentrations.
Screens
Screens are widely used in minerals mining and processing
operations for separations, classifications and
beneficiations. They are similar to hydrocyclones in that
they are restricted to removing the larger (<50-100 micron)
particle size suspended solids of the waste water, which can
then often be sold as useful product. Screens are not
practical for removing the smaller suspended particles.
Filtration
Filtration is accomplished by passing the waste water stream
through solids-retaining screens, cloths, or particulates
such as sand, gravel, coal or diatomaceous earth using
gravity, pressure or vacuum as the driving force.
Filtration is versatile in that it can be used to remove a
wide range of suspended particle sizes,
The large volumes of many waste water streams found in
minerals mining operations require large filters. The cost
of these units and their relative complexity, compared to
settling ponds, has restricted their use to a few industry
segments committed to complex waste water treatment.
186
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DISSOLVED MATERIAL TREATMENTS
Unlike ubiquitous suspended solids which need to be removed
from minerals mining and processing waste waters, dissolved
materials are a problem only in scattered instances in the
industries covered herein.
Treatments for dissolved materials are base4 on either
modifying or removing the undesired materials. Modification
techniques include chemical treatments such as
neutralization. Acids and alkaline materials are examples
of dissolved materials modified in this way. Most removal
of dissolved solids is accomplished by chemical
precipitation. An example of this is given below, the
removal of fluoride by liming:
2F- + Ca(OH)2 ='CaF2 + 2OH~
With the exception of pH adjustment, chemical treatments for
abatement of waterborne wastes are not common in this
industry segment.
Neutralization
Some of the waterborne wastes of this study, often including
mine drainage water, are either acidic or alkaline. Before
disposal to surface water or other medium, excess acidity or
alkalinity needs to be controlled to the range of pH 6 to 9.
The most common method is to treat acidic streams with
alkaline materials such as limestone, lime, soda ash, or
sodium hydroxide. Alkaline streams are treated with acids
such as sulfuric. Whenever possible, advantage is taken of
the availability of acidic waste streams to neutralize basic
waste streams and vice versa. Neutralization often produces
suspended solids which must be removed prior to waste water
disposal.
pH Control
The control of pH may be equivalent to neutralization if the
control point is at or close to pH 7. Sometimes chemical
addition to waste streams is designed to maintain a pH level
on either the acidic or basic side for purposes of
controlling solubility.
An example of pH control being used for precipitating
undesired pollutants is:
(1) Fe+3 + 30H- = Fe(OH)3
This reaction is used for removal of iron contaminants.
187
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SUMMARY OF TREATMENT TECHNOLOGY APPLICATIONS , LIMITATIONS
AND RELIABILITY
Table 13 summarizes comments on the various treatment
technologies as they are utilized for the minerals mining
industry. Estimates of the efficiency with which the
treatments remove suspended or dissolved solids from waste
water as given in the table need to be interpreted in the
following context.
These values will obviously not be valid for all circum-
stances, concentrations or materials, but should provide
general guidance for treatment performance capabilities.
Several comments may be made concerning the values:
(1) At high concentrations and optimum conditions, all
treatments can achieve 99 percent or better removal of
the desired material;
(2) At low concentrations, the removal efficiency drops off.
(3) Minimum concentration ranges achievable will not hold in
every case. For example, pond settling of some
suspended solids might not achieve less than the
100 mg/1 level. This is not typical, however, since
many such pond settling treatments can achieve 10 to
20 mg/1 without difficulty. Failure to achieve the
minimum concentration levels listed usually means that
either the wrong treatment methods have been selected or
that an additional treatment step is necessary (such as
a second pond or a polish filtration).
PRETREATMENT TECHNOLOGY
Most construction minerals mining operations have waste
water containing only suspended solids. Suspended solids is
a compatible pollution parameter for publicly-owned
activated sludge or trickling filter wastewater treatment
facilities. However, most of these mining and processing
operations are located in isolated regions and have no
access to these treatment facilities. No instances of
discharge to publicly-owned treatment facilities were found
in the industry segment of this volume.
In the relatively few instances where dissolved materials
are a problem, pH control and some reduction of hazardous
constituents such as fluoride would be required. Lime
treatment is usually sufficient to accomplish this.
188
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TABLE 13. Summary of Technology, Applications, Limitations and Reliability
Wosle
Woler
Constituents
Suspended
Solids
Dissolved
Solids
, Treolfiwiit
. PlOCCS!
(I) Pond
Settling
(2) C Wirier
Thicfcen=rs
(3) Hydro-
cyclones
(4) Tube ond
Lomello
Settlers
(5J Sereens
(6) Rotary
Vacuum
Filters
(7) Solid E0.vl
Centrifuge
(BJ Leaf ond
Pressure
Fillers
(9) Cartridge
and Ccndlc
Fillers
(10) Sand and
Mixed
Medio
Niters
(1} Nwi-oli-
fcolion rnd
pH Coni'ol
(?) Pietipito-
lion
AppKtotion
Uir-d For all
cancellations
Usfd for oil
con ccrit rations
Ticmovol of larger
particle sizes
Removal of 'mailer
particle sires
Removal of larger
port Tele sizes
Mainly for sludges
ond olher Iiiyli
suspended solids
streams
Mainly for sludges
and other hieih
suspended solids
streams
Used over wide
concfrirffitiOn
range
Mainly for [joliifi-
ing filliolions of
suspended solids
Moin!y for polisn-
rrig filiations of
impended solids
GcHcrol
Grcadiy u-.r,( to
ICMOVC ioluhU-j
Perccint
Solids
Removal
60-99
60-99
50-99
90-99
50-99
90-99
60-99
90-79
50-99
.50-99
99
50-7?
Enprctpd
Cofcen-
1 ret ion
(rVLV
5-200
5-1000
_
5-1000
10-100
2-10
2-50
Minimum
Concen-
t rat ion
Achievable
(r.a'l)
5-30
5-30
-
5-30
5-30
2-10
2-10
NA
NA
0-JO
0-10
Avoilo-
billty
of
Equip-
m-'nt
none
needed
readily
available
reedy
available
readily
available
ready
a/ciilable
read! I/
available
readily
available
readily
available
readily
available
readily
available
r.-Tlily
oval lab id
,,;My
Leod
Tiwe
(monllis)
1-12
3-24
3-12
3-12
3-12
3-12
3-12
3-6
1-3
3-6
3-12
3-6
Spoee
or
Land
Nei-ded
large
t-500 acrei
imall
0.05-1,0
acres
-------
NON-WATER QUALITY ENVIRONMENTAL ASPECTS, INCLUDING ENERGY
REQUIREMENTS
The effects of these treatment and control technologies on
air pollution, noise pollution, and radiation are usually
small and not of any significance.
Large amounts of solid waste in the form of both solids and
sludges are formed as a result of all suspended solids
operations as well as chemical treatments for neutraliza-
tion, and precipitations. Easy-to-handle, relatively dry
solids are usually left in settling ponds or dredged out
periodically and dumped onto the land. Since mineral mining
properties are usually large, space for such dumping is
often available.
For those waste materials considered to be non-hazardous
where land disposal is the choice for disposal, practices
similar to proper sanitary landfill technology may be
followed. The principles set forth in the EPA1s Land
Disposal of Solid Wastes Guidelines (CFR Title 40, Chapter
1; Part 241) may be used as guidance for acceptable land
disposal techniques.
For those waste materials considered to be hazardous,
disposal will require special precautions. In order to
ensure long-term protection of public health and the
environment, special preparation and pretreatment may be
required prior to disposal. If land disposal is to be
practiced, these sites must not allow movement of pollutants
such as fluoride and radium-226 to either ground or surface
water. Sites should be selected that have natural soil and
geological conditions to prevent such contamination or, if
such conditions do not exist, artificial means (e.g*,
liners) must be provided to ensure long-term protection of
the environment from hazardous materials. Where
appropriate, the location of solid hazardous materials
disposal sites should be permanently recorded in the
appropriate office of the legal jurisdiction in which the
site is located.
In summary, the solid wastes and sludges from the mineral
mining industry waste water treatments are very large in
quantity. Since these industries generally have sufficient
space and earth-moving capabilities, they manage it with
greater ease than most other industries.
For the best practicable control technology currently
available the added annual energy requirements are estimated
to be 1.45 x 1011 kcal. This amounts to estimated 13
percent increase in the present estimated energy use for
pollution control technologies in this segment of the
190
-------
mineral mining and processing industry. Over 80 percent of
this added energy requirement is attributed to wet
processing of crushed stone.
191
-------
-------
SECTION VIII
COST, ENERGY, WASTE REDUCTION BENEFITS AND NON-WATER
ASPECTS OF TREATMENT AND CONTROL TECHNOLOGIES
SUMMARY
The construction materials segment of the mineral mining and
processing industry has very large volumes of both products
and waste water for treatment. Overall industry waste water
treatment costs reflect this. Unlike manufacturing
operations, where raw materials for the process may be
selected and controlled as to purity and uniformity,
construction materials mining and processing operations are
themselves largely controlled by the purity and uniformity
of the ores or raw materials involved. Operations have to
be located at or near the mineral deposits. Since they are
mostly low cost commodities, used mainly in urban or
suburban areas the mining and processing must normally be
done close to market outlets. Both availability and cost
for land necessary for treatment are significantly
influenced by this necessary location. Suburban and urban
land is becoming more difficult to obtain and more costly.
Treatment costs often vary widely with the character of
pollutants involved. A salient example involves the wide
variation of of suspended solids. Effluents with large
particle size wastes have high settling rates while small or
colloidal suspended particles are slow and difficult to
settle, requiring large ponds or thickeners, flocculating
treatments or other devices for removing suspended solids in
many cases.
As land costs increase, more sophisticated treatment techno-
logies will come into use that require less land space.
These include the use of flocculants and coagulants to
induce more rapid pond settling and mechanical settling and
separation devices such as thickeners and clarifiers, tube
and lamella separators, filters, centrifuges and
hydrocyclones.
In general, facility size and age have little influence on
the type of waste effluent. The amounts and costs for their
treatment and disposal are readily scaled from facility size
and are not greatly affected by facility age.
Geographical location is important. Mines and processing
facilities located in dry western areas rarely require major
waste water treatment or have subsequent disposal problems.
193
-------
Terrain and land availability are also significant factors
affecting treatment technology and costs. Lack of
sufficient flat space for settling ponds forces utilization
of mechanical thickeners, clarifiers, or settlers. On the
other hand, advantage is often taken of valleys, hills,
swamps, gullies and other natural configurations to provide
low cost pond and solid waste disposal facilities.
In view of the large number of mines and beneficiation
facilities and the significant variables listed above, costs
have been developed for representative mines and processing
facilities rather than specific facilities that may have
advantageous geographical, terrain or ore composition. A
summary of cost and energy information for the present level
of waste water treatment technology for this segment is
given in Table 14. Present capital investment for waste
water treatment in the construction materials segment is
estimated as $141,000,000.
COST REFERENCES AND RATIONALE
Cost information contained in this report was assembled
directly from industry, from waste treatment and disposal
contractors, engineering firms, equipment suppliers,
government sources, and published literature. Whenever
possible, costs are taken from actual installations,
engineering estimates for projected facilities as supplied
by contributing companies, or from waste treatment and
disposal contractors quoted prices. In the absence of such
information, cost estimates have been developed insofar as
possible from facility-supplied costs for similar waste
treatments and disposal for other facilities or industries.
Interest Costs and Equity Financing Charges
Capital investment estimates for this study have been based
on 10 percent cost of capital, representing a composite
number for interest paid or return on investment required.
Time Basis for Costs
All cost estimates are based on August 1972 prices and when
necessary have been adjusted to this basis using the
chemical engineering facility cost index.
Useful Service Life
The useful service life of treatment and disposal equipment
varies depending on the nature of the equipment and process
involved, its usage pattern, maintenance care and numerous
other factors. Individual companies may apply service lives
based on their actual experience for internal amortization.
194
-------
TABLE 14
CAPITAL INVESTMENTS AND ENERGYCON5UMPTION
OF PRESENT WASTEWATER TREATMENT FACILITIES
Subcotegory
Capital
Spent
(dollars)
Present
Energy
'Use
(kcal xlO6)
Total
Annual
Costs ($Akg
produced)
Dimension Stone
Crushed Stone, Dry
Crushed Stone, Wet
Crushed Stone, Flotation
Crushed Shell, Dredging
Construction S&G, Dry
Construction S&G, Wet
Construction S&G,
(dredging with on-
land processing)
Construction S&G,
(dredging with on-
board processing)
Industrial Sand, Dry
Industrial Sand, Wet
Industrial Sand,
(acid and alkaline
flotation)
Industrial Sand,
(HF flotation)
Gypsum, Dry
Gypsum, Wet Scrubber
Gypsum, Heavy media
separation
Bituminous Limestone
Oil Impregnated
Diatomite
Gilsonite
Asbestos, Dry
Asbestos, Wet
Wollastonite
Perlite
Pumice
Vermiculite
Mica, Dry Processing
Mica, Wet Grinding
Mica, Wet Ben. w/o
clay by-products
Mica, Wet Ben. with
clay by-products
TOTAL
1,100,000
26,400,000
50,000
90,000,000
3,130,000
220,000
8,860,000
8,770,000
120,000
small
30,000
25,000
25,000
< 50,000
620,000
small
780,000
550,000
141,000,000
4,000 0.20
. . . no waste water . . .
659,500 I 0.07
1,400 ' 0.07
. no waste wafer treatment
. . . no waste water . . .
325,000
11,100
0.08
0.08
. . no waste water treatment .
small
37,800
30,200
0.02
0.18
0.20
500 0.23
no waste water. .
small
small
0.01
0.05
no wasfe water
no waste wafer
125 0.08
. no waste water .
small | 0.09
. no process water ,
. no process water .
small
2,400
0.01
0.62
no process waste wafer
small
3,100
2,300
1,080,000
0.22
5.0
5.5
195
-------
Internal Revenue Service provides guidelines for tax
purposes which are intended to approximate average
experience. Based on discussions with industry and
condensed IRS guideline information, the following useful
service life values have been used:
(1) General process equipment 10 years
(2) Ponds, lined and unlined 20 years
(3) Trucks, bulldozers, loaders
and other such materials
handling and transporting
equipment. 5 years
Depreciation
The economic value of treatment and disposal equipment and
facilities decreases over its service life. At the end of
the useful life, it is usually assumed that the salvage or
recovery value becomes zero. For IRS tax purposes or
internal depreciation provisions, straight line, or
accelerated write-off schedules may be used. straight line
depreciation was used solely in this report.
Capital Costs
Capital costs are defined as all front-end out-of-pocket
expenditures for providing treatment/disposal facilities.
These costs include costs for research and development
necessary to establish the process, land costs when
applicable, equipment, construction and installation,
buildings, services, engineering, special start-up costs and
contractor profits and contingencies.
Annual Capital Costs
Most if not all of the capital costs are accrued during the
year or two prior to actual use of the facility. This
present worth sum can be converted to equivalent uniform
annual disbursements by utilizing the Capital Recovery
Factor Method:
Uniform Annual Disbursement =P_i (1+i)nth power
(1+i)nth power - 1
Where P = present value (capital expenditure), i =
interest rate, X/100, n = useful life in years
The capital recovery factor equation above may be
rewritten as:
Uniform Annual Disbursement = p (CR - i5t - n)
196
-------
Where (CR - i.% - n) is the Capital Recovery Factor for
i% interest taken over "n" years useful life.
Land Costs
Land-destined solid wastes require removal of land from
other economic use. The amount of land so tied up will
depend on the treatment/disposal method employed and the
amount of wastes involved. Although land is non-depreciable
according to IRS regulations, there are numerous instances
where the market value of the land for land-destined wastes
.has been* significantly reduced permanently, or actually
becomes unsuitable for future use due to the nature of the
stored waste. The general criteria applied to costing land
are as follows:
(1) If land requirements for on-site treatment/disposal are
not significant, no cost allowance is applied.
(2) Where on-site land requirements are significant and the
storage or disposal of wastes does not affect the
ultimate market value of the land, cost estimates
include only interest on invested money.
(3) .For significant on-site land requirements where the
ultimate market value and/or availability of the land
has been seriously reduced, cost estimates include both
capital depreciation and interest on invested money.
(**) Off-site treatment/disposal land requirements and costs
are not considered directly. It is assumed that land
costs are included in the overall contractor's fees
along with its other expenses and profit.
(5) In view of the extreme variability of land costs,
adjustments have been made for individual industry
situations. In general, isolated, plentiful land has
been costed at $2,470/hectare ($1,000/acre).
Operating Expenses
Annual costs of operating the treatment/disposal facilities
include labor, supervision, materials, maintenance, taxes,
insurance and power and energy. Operating costs combined
with annualized capital costs equal the total costs for
treatment and disposal. No interest cost was included for
operating (working) capital. since working capital might be
assumed to be one sixth to one third of annual operating
costs (excluding depreciation), about 1-2 percent of total
operating costs might be involved. This is considered to be
well within the accuracy of the estimates.
197
-------
Rationale for Representative Facilities
All facility costs are estimated for representative
facilities rather than for any actual facility.
Representative facilities are defined to have a size and age
agreed upon by a substantial fraction of the manufacturers
in the subcategory producing the given mineral, orf in the
absence of such a consensus, the arithmetic average of
production size and age for all facilities. Location is
selected to represent the industry as closely as possibly.
For instance, if all facilities are in northeastern U.S.,
typical location is noted as "northeastern states". If
locations are widely scattered around the U.S., typical
location would be not specified geographically. It should
be noted that the unit costs to treat and dispose of
hazardous wastes at any given facility may be considerably
higher or lower than the representative facility because of
individual circumstances.
Definition of Levels of Treatment and Control
Costs are developed for various types and levels of
technology:
Minimum jor basic level). That level of technology which is
equalled or exceeded by most or all of the involved
facilities. Usually money for this treatment level has
already been spent (in the case of capital investment) or is
being spent (in the case of operating and overall costs).
B,C,D,E Levels - Successively greater degrees of treatment
with respect to critical pollutant parameters. Two or more
alternative treatments are developed when applicable.
Rationale for Pollutant Considerations
(1) All non-contact cooling water is exempted from treatment
(and treatment costs) provided that it is not
contaminated by process water and no harmful pollutants
are introduced.
(2) Water treatment, cooling tower and boiler blowdown
discharges are not treated provided they are not
contaminated by process water and contain no harmful
pollutants.
(3) Removal of dissolved solids, other than harmful
pollutants, is not included,
Mine drainage treatments and costs are generally
considered separately from process water treatment and
costs. Mine drainage costs are estimated for all
mineral categories for which such costs are a
significant factor.
198
-------
(5) All solid waste disposal costs are included as
the cost development.
Cost Variances
part of
The effects of ager location, and size on costs for
treatment and control have been considered and are detailed
in subsequent sections for each specific subcategory.
INDUSTRY STATISTICS
The estimated 1972 selling prices for the individual
minerals in this report are summarized as follows. . These
values were taken from minerals industry yearbooks and
Bureau of Census Publications.
Mineral Product
Estimated 1972 Selling Price Range,
$/kkg ($/ton)
crushed stone 1.90 (1-72)
construction
sand and gravel 1.36 (1.23)
industrial sand 4.20 (3.81)
gypsum 4.10 (3.75)
asbestos 112 (102)
dimension stone 19.80 (18.00)
wollastonite 44 (40)
bituminous limestone 2.20 est. (2.00)
gilsonite unknown
oil impregnated
diatomite 71.71 (65.19)
perlite 12.47 (11.34)
pumice 1.88 (1-71)
vermiculite 26.41 (24.01)
mica 29.93 (27.21)
minimum
199
-------
INDIVIDUAL MINERAL WASTE WATER TREATMENT AND
DISPOSAL COSTS
DIMENSION STONE
Of the sixteen facilities visited, thirteen use settling
ponds for removal of suspended solids from waste water, two
had no treatment and the other facility uses a raked
settling tank. Approximately one-third of these facilities
have total recycle after settling. Pond settling and
recycle costs are given in Table 15. Since pond cost is the
major investment involved, cost for settling without
recycling is similar.
Cost Variances
Age. The sixteen visited facilities range from 10 to
142 years. There was no discernible correlation between
facility age and treatment technology or costs.
Location. The facilities in this category are widely
scattered around the U.S. The general low level of waste
water treatment costs for dimension stone facilities exists
independently of location.
Size. Facility sizes ranged from 2,720 to 64,100 kkg/yr
(3,000 to 70,650 tons/yr). Since pond cost s vary
significantly with size in the less than one acre category,
cost -variance with size " may be estimated to be 0.8
exponential for capital and linear for operating expenses.
Cost Basis for Table 15
Waste water treatment cost details for the typical facility
values at Level C are shown below. Level B costs are
similar except for recycle equipment.
Production: 18,000 kkg/yr (20,000 tons/yr)
8 hr/day; 250 days/yr
Water Use and Waste Characteristics:
4,170 1/kkg (1,000 gal/ton) of product
2% of product in effluent stream
5,000 mg/1 TSS in raw effluent
360 kkg/yr (400 tons/yr) waste, dry basis
280 cu. m. (10,000 cu. ft.) wet sludge per year
1,300 kg solids per cu. m. sludge (80 Ib/cu. ft.)
Treatment; Recycle of wash water after passing through
a one acre settling pond
200
-------
COST
SUBCATEGORY
PLANT SIZE
TABLE 15
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
Dimension Stone
18,000
PLANT AGE 50 YEARS
METRIC TONS PER YEAR OF Product
PLANT LOCATION near population center
INVESTED CAPITAL COSTS!
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 a M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/ METRIC TON product
WASTE LOAD PARAMETERS
(kg/metric ton of product )
Suspended Solids
RAW
WASTE
LOAD
20
LEVEL
A
(MINI
0
0
0
0
0
0
20
B
10,000
1,600
900
200
2,800
0.16
0.8
C
13,600
2,200
950
400
3,550
0.20
0
D
E
LEVEL DESCRIPTION:
A — direct discharge
B — settling, discharge
C — settling plus recycle
201
-------
Cost Rational:
Pond cost $10,000/acre
Total pipe cost $1/diam/linear ft,
Total pump cost $100/HP
Power costs $0.02/kwh
Maintenance 5% of capital
Taxes and insurance 2% of capital
Capital recovery factor 0.1627
202
-------
CRUSHED STONE
The crushed stone industry produces approximately one
billion tons annually, of this, approximately 75 percent is
limestone and 25 percent is granite. The industry has been
subcategorized in the following manner:
(1) dry process
(2) wet process
(3) flotation
DRY PROCESS
An- estimated seventy percent of the crushed granite and
limestone facilities use no contact process water. There
are estimated 3,200 facilities in this category, accounting
for 640 million kkg/yr (700 million tons/yr).
WET PROCESS
Typical Facility Data
A typical wet crushed stone operation is assumed to produce
180,000 kkg/yr (200,000 tons/yr), half of which is washed,
and half is dry processed. The assumed wash water usage is
1,000 1/kkg (240 gal/ton), and the assumed waste content is
6% of the raw material. The cost data are presented in
Table 16.
Waste water Treatment
Levels B and C - Simple Settling, Discharge, or Recycle
The waste water is passed through a one acre settling pond
and discharged or recycled back to the facility. The pond
is dredged periodically and the sludge is deposited on site.
Level D - Settling with Flocculants, Recycle
The waste water is treated with a flocculant and passed
through a one acre settling pond. The effluent is then
recycled. It is rare that a flocculant would be needed to
produce an effluent quality acceptable for recycle in a
crushed stone operation.
Cost Basis for Table 16
203
-------
COST
TABU: 16
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SUBCATEGORY Crushed Stone7 Wet Process
PLANT SIZE 180,000 METRIC TONS PER YEAR OF Crushed Stone
PLANT AGE 40 YEARS
PLANT LOCATION rural location near population center
INVESTED CAPITAL COSTS:
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 a M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kg /metric ton of product )
Suspended Solids
RAW
WASTE
LOAD
60
LEVEL
A
(WIN)
0
0
0
0
0
0
60
B
14,500
2,400
6,400
1,000
9,800
0.054
0.2
C
19,000
3,100
6,400
2,000
11,500
0.064
0
D
22,500
3,700
7,400
2,000
13,100
0.073
0
E
LEVEL DESCRIPTION:
A — direct discharge
B —settling pond, discharge
C ™ settling pond, recycle
D — flocculant, settling pond, recycle
204
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Level B
Pond Cost $10,000
Pumps and piping 4,500
Power 1,000
Pond cleaning 6,000
Taxes and insurance 400
Level c
Total pond cost $10rOOO
Total pump and piping cost 9,000
Annual capital recovery 3,100
Power 2,000
Pond cleaning 6,000
Taxes and insurance 400
Level D
Additional capital flocculant equipment $ 3,500
Additional annual capital 600
Annual chemical cost 1,000
Cost Variances
(1)_ Granite .fines settle somewhat slower than limestone
fines. As a result, recirculation granite ponds
generally run about 50% larger than those of limestone
for the same capacity facility.
(2) The amount of waste in the effluent is largely depended
on the type of product. Six percent was chosen as an
average value. Range of wastes is 2 to 12 percent.
Cost to treat per ton of product is approximately
proportional to percent waste.
The amount of stone washed in any given year varies with the
demand for a washed product. The capital costs for
treatment are more readily absorbed when a large portion of
the stone is washed.
Capital costs are estimated to vary as the 0,9 power of size
and operating expenses are proportional to size.
Estimation of Total Costs for Subcategory
There are an estimated 1600 facilities in this category
producting an estimated 140 million kkg (150 million tons)
of washed stone along with 140 million kkg (150 million
tons) of dry processed stone annually. An estimated 500 of
these 1600 facilities are presently on complete recycle.
The remaining 1100 facilities produce approximately 91
205
-------
million kkg/yr (100 million -tons/yr) of stone, 5056 of which
is washed.
The average cost increase per ton for the wet process
crushed stone industry would be $0,044 ($0.048/kkg) to
convert to recycle. The capital expenditure for the same is
estimated to be $10,000,000.
CRUSHED STONE, FLOTATION PROCESS
There are an estimated eight facilities in this subcategory,
with a combined estimated annual production of 500,000 tons.
The process is identical to that of wet crushed stone,
except for an additional flotation step, using an additional
5% of process water. The wash water can be recycled as in
wet processing, but the flotation water cannot be directly
recycled due to the complex chemical processes involved.
The two waste streams can be combined; however, and be
recycled in the washing process. The flotation process
would require fresh input.
Typical Facility Data
The treatment used is settling ponds and recycle. Assuming
a 5% loss (equivalent to the input from flotation) from the
combined effects of percolation and evaporation, discharge
would be eliminated under normal conditions.
Estimation of Total Costs for Subcategory
It is estimated that two of the eight facilities in this
subcategory are presently recycling their waste water. The
remaining six could achieve recycle with total capital cost
of $200,000. The selling price of the product is $33/kkg,
($30/ton), therefore the increase in operating cost due to
recycle is approximately 0.2 percent.
206
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CONSTRUCTION SAND AND GRAVEL
The construction sand and gravel industry has been divided
into three subcategories:
(1) Dry process
(2) Wet process
(3) River dredging with on-land processing
DRY PROCESS
Typical Facility Data
A typical dry process sand and gravel facility produces
454,000 kkg/yr (500,000 tons/yr) of construction sand and
gravel. There is no process water use, no non-contact
cooling water and no pit pumpout.
Treatment Options
Since there is no water use or waste water generated, treat-
ment is not required.
Cost/Benefit Analysis of Treatment Technology
There is no cost of treatment at a typical facility.
Cost variances
Pit pumpout is required at some facilities during periods of
high rainfall. Some facilities also have a non-contact
cooling water discharge. The pit pumpout in some of these
cases is settled in a sump or pond.
Age, location, and production have no consistent effect on
waste waters from facilities in this subcategory, or on
costs to treat them.
There are an estimated 750 facilities in this subcategory
representing a production of 129 x 106 kkg/yr
(143 x 106 tons/yr).
WET PROCESS
Typical Facility Data
The average production rate of facilities in this
subcategory is 130,000 kkg/yr {143,000 tons/yr). Median
facility size is approximately 227,000 kkg/yr
(250,000 tons/yr). This is selected as representative for
facility size.
207
-------
10 percent of raw material in waste stream (68,000 mg/1)
11f400 1/min (3,000 gal/min) used for washing
all particles down to 200 mesh (74 micron) are recovered
for sale by screw classifier cyclones, etc.
Cost Basis for Table 17
Level B: 5.6 acre settling pond and discharge of effluent.
Pond cost $28,000
Pump cost 2,000
Pipe cost 3,000
Annual power 300
Taxes and insurance 800
Maintenance 800
Iievel C: 5,6 acre settling pond followed by recycle of
waste water.
Total pond cost $28,000
Total pump cost 3,000
Total pipe cost 6,000
Power, annual 600
Taxes and insurance 1,000
Maintenance 1,000
Level D: Two silt removal ponds of 0.04 ha (0.1 acre) each
are "used alternately prior to the main settling pond of
5.6 acres. The life of the main pond is greatly increased
as most of the solids are removed in the primary ponds. One
small pond is dredged while the other is in use. The sludge
is deposited on site.
Total pond cost $30,000
Annual pond cost 3,600
Total pump and piping 10,000
Annual pump and piping 1,600
Annual dredging and
sludge disposal 20,000
Power 600
Taxes and insurance 1,000
Level E: Mechanical thickener is used along with a
flocculating agent to produce an effluent of 250 mg/1 for
recycle. The underflow sludge is transported to a 4 acre
sludge disposal basin at a cost of $1.1/kkg ($l/ton)
208
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COST
TABLE 17
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SUBCATEGORY Construction Sand & Grave!, Wet Process
PLANT SIZE 227,000
PLANT AGE 5 YEARS
METRIC TONS PER YEAR OF product
PLANT LOCATION
population center
INVESTED CAPITAL COSTS!
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 8 M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kq/metric fon of product )
Suspended Solids
RAW
WASTE
LOAD
100
LEVEL
A
(WIN)
0
0
0
0
0
0
100
B
33,000
5,400
1,600
300
7,300
0.03
0.4
C
37,000
6,000
2,000
600
8,600
0.04
0
D
40,000
5,200
21,000
600
26,800
0.12
0
E
50,000
8,100
29,200
400
37,700
0.17
0
F
180,000
29, 200
41,400
600
71,200
0.31
0
G
21,600
2,600
28,100
400
31,100
0.14
0
LEVEL DESCRIPTION:
A — direct discharge
B — settling, discharge
C — settling, recycle
D — two silt removal ponds, settling pond, recycle
E — flocculant, mechanical thickener and recycle. Transportation of sludge to disposal basin.
F — flocculant, inclined plate settlers, and recycle effluent. Transport sludge to disposal basin,
G— flocculant, settling basip, recycle
209
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Total thickener cost $ 18,500
Sludge disposal basin cost 20,000
Polymer feed system cost 1,600
Pump and piping 9,700
Annual sludge transportation 25,000
Annual chemical cost 2,200
Annual power 400
Maintenance 1,000
Taxes and insurance 1,000
Level F: Inclined plate settlers are used to produce an
effluent of 250 mg/1 which is recycled back to the process.
A coagulant is added prior to the settlers to increase
settling rate. The underflow sludge is transported to a
4 acre settling basin at a cost of one dollar per ton of
solids. It should be noted that no case of an inclined
plate settler successfully treating a sand and gravel waste
was found. The advantage of this system is the small area
required.
Inclined plate settler cost $150,000
Pumping and piping 10,000
Sludge disposal basin 20,000
Sludge transportation 25,000
Chemical 2,000
Maintenance 7,200
Taxes and insurance 7,200
Power 600
Level G: Flocculant added, 1 acre settling pond is used for
treatment, and effluent is recycled to the process. The
sludge is dredged and deposited on site at a cost of
$0.55/kkg ($0.50/ton).
Total pond cost $ 10,000
Polymer mixing unit 1,600
Pump and piping 10,000
Chemical cost 2,200
Dredging 25,000
Power 400
Taxes and insurance 900
Cost Variances
Production, Production rate in this subcategory varies from
10,900 to 1,800,00 kkg/yr (12,000 to 2,000,000 tons/yr).
Waste volume and water flow vary proportionately with
production. As a result, settling . area varies
proportionately with production. Pond capacity also varies
210
-------
proportionately with sludge volume, and thus production.
Pumping, piping and power costs may also be considered to be
roughly proportional to water flow, and production. Thus,
the capital costs for Levels B, C, D, and G are estimated to
vary with size to the 0.9 power. operating costs not
related to capital are approximately proportional to size.
Levels E and F use equipment for clarification rather than
ponds. Capital costs for them should vary by an exponential
factor of 0.7 to size. Operating costs not based on
capitalization are approximately proportional to size.
Waste Content. A facility having a waste content other than
ten percent should require a proportionately different water
usage. The settling area required to obtain recyclable
effluent should be proportional to waste content. Dredging
and pumping are also proportional to waste content. Thus
the treatment cost per ton of product should vary roughly
proportionately with waste content. Waste content can vary
from less than 5* to 3036.
Topography. A canyon or hillside can greatly reduce the
cost of pond building. Also, a wet land can increase the
cost of building a pond.
Particle Size* Suspended solids average particle size
greater than the one shown would mean a proportionately
smaller settling area would be need to produce recyclable
effluent. A smaller particle size could be countered with
the use of a flocculant, if necessary.
Coagulant Efficiency. An increase in settling rate would
require a proportionately smaller settling area. A settling
rate increase due to the use of coagulant of 100 times was
assumed, based on laboratory tests and industry supplied
information.
Estimated Total Costs for Subcategory
There are an estimated 4,250 facilities in the wet
processing subcategory, producing 573 million tons/yr. Of
these, an estimated 5056 (2,125 facilities) are presently
recycling their effluent. An e stimated 25% of the se
(1,063 facilities) have no discharge under normal conditions
due to evaporation and/or percolation in settling ponds.
The remaining 25% (1,063 facilities) presently have a
discharge. It is estimated that 9056 of the facilities
having a discharge (956 facilities) presently have a ponding
system. These latter facilities could in most cases convert
their ponds to a recycle system by installing pumps and
pipe, with the use in some cases of a coagulant.
211
-------
Thus the facilities in this subcategory without present
ponding systems are estimated to be 2.5X (107 facilities).
Almost all of these facilities could install treatment
options c, D, or G, which are the least expensive.
Options E or F would only be required in an urban environ-
ment where sufficient settling area is not available on
site.
The 956 facilities with settling pond discharges produce an
estimated 168 million tons/yr.
The installation of a pump and piping system, and the
addition of a flocculant would result in a total annual cost
per ton of $0.018 per ton, or the total capital expenditure
required represents about 7.4 million dollars.
The 107 facilities which are presently discharging without
treatment produce an estimated 18 million tons/yr. It is
assumed that these facilities may achieve recycle for an
average annualized cost of $0,10/ton. It should be noted
that a small fraction of these 107 facilities have no land
for settling ponds, and that no sand and gravel facility
utilizing options E or F (no ponds) to achieve recycle was
found.
Seventy-five percent of the facilities in this subcategory
presently are on recycle, or have no point source discharge.
23.555 of the facilities are not on recycle but have ponds.
They require a total capital expense of 7.4 million dollars,
and an annualized cost of $0.018 per ton.
The facilities not having any ponds could achieve recycle
for a capital cost of 1.7 million dollars. The annualized
increase in production costs would average $0.10/ton.
The entire subcategory of wet processed sand and gravel
could eliminate discharge of process effluent for a total
capital expense of about 10 million dollars. The average
cost of production would rise $0.017/ton. This price rise
represents an average rise of 0.6 percent assuming an
average selling price of $3 per ton.
RIVER DREDGING, ON-LAND PROCESS
Typical Facility Data
Production: 360,000 kkg/yr (400,000 tons/yr)
Assume same treatment options as in wet process facility.
Costs of waste water treatment for the typical facility can
be derived from these presented in Table 17 by applying the
appropriate size factors.
212
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Cost Variances
Factors affect treatment and costs in the same manner as
described for wet processing.
Estimated Total Costs for Subcategory
There are an estimated fifty river dredging operations with
on-land processing, producing 16,700,000 tons/yr of sand and
gravel. An estimated 50% of the facilities producing 50% of
the volume have no point source discharge at this time. It
is estimated that twenty-two of the remaining twenty-five
facilities have settling ponds at the present time. Recycle
should be achievable with the aid of a flocculant for an
increased production cost of $0.02/kkg ($0.018/ton)-
The total capital cost for the subcategory is estimated to
be $1,500,000. The average increase in production costs
would be $0.01 per ton. This represents an average
production cost increase of 0.3% based on an average selling
price of $3 per ton.
213
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INDUSTRIAL SAND
The industrial sand industry was divided into four sub-
categories:
(1) Dry process
(2) Wet process
(3) Acid and alkaline flotation
(4) HF flotation.
DRY PROCESSING
Approximately 10 percent of the industrial sand operations
fall into this subcategory. The only water involved comes
from dust collectors used by some facilities. Of the five
dry process facilities surveyed, two have such scrubbers -
one without treatment and the other with pond settling and
complete recycle.
Cost For Dry Process Scrubber Water Treatment
Treatment is by addition of 5 mg/1 flocculating agent and
recycle through a one acre settling pond.
Assumptions:
167,000 I/day (44,000 GPD) scrubber water
5 days/week; 8 hours/day
flocculant cost - $1/lb
piping cost - $1/inch diam/linear foot
pump cost - $1/HP/yr
power cost - $.02/kwh
pond cost - $10,000/acre
TSS in raw waste - 30,000 mg/1
pond cleaning - $0.5/ton of sludge
Capital Costs:
pond $10,000
piping and pump 3,000
polymer mixing unit 1,500
total capital 14,500
annual capital
recovery 2,360
214
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Operating Costs:
pond cleaning $ 700
power 150
chemical 50
maintenance 725
taxes and insurance 290
total annual operating 1,700
total annual recycle
costs 4,000
WET PROCESS
The wet process uses washing and screening operations
similar to those for construction sand and gravel.
Treatment of the waste water also used the same
technologies. By use of ponds, thickeners and clarifiers,
three out of the four wet process facilities studies have no
discharge of process water. Table 18 summarizes the costs
for two treatment technologies.
Cost Basis for Table 18
Level A; 39 acre settling pond, discharge effluent
pond cost $60,000
pump cost 3,000
piping cost 6,000
Level B
Capital Costs
settling pond area 39 acres
pond cost $60,000
pump costs 6,000
piping costs 13,500
total capital $79,500
Annual Investment Costs
pond costs (20 yr life d 10% interest) = 7000
pump costs (5 yr life o> 10% interest) = 1500
piping costs (10 yr life 310% interest) = 2200
total 10,700
215
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COST
TABLE 18
FOR A REPRESENTATIVE PLANT
{ALL COSTS ARE CUMULATIVE)
SUBCATEGORY Industrial Sand, Wet Process
PLANT SIZE 180,000 METRIC TONS PER YEAR OF product
PLANT AGE 10 YEARS
PLANT LOCATION near population center
INVESTED CAPITAL COSTS!
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 a M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kg/metric ton of product )
Suspended Solids
RAW
WASTE
LOAD
35
LEVEL.
A
(MIN)
69,000
8,000
^800
1,000
11,800
0.07
0.7
B
79,500
10,700
3,200
2,000
15,900
0.09
0
C
155,000
25,200
21,900
2,000
49,100
0.26
0
D
E
LEVEL DESCRIPTION:
A — settle^discharge
B — settle, recycle
C — mechanical thickener with coagulant, overflow is recycled to process. Underflow
is passed through a settling basin. Effluent from the settling basin is also recycled
to process.
216
-------
Operating Costs
maintenance costs a 2% of capital = 1600
power cost d $.02 per kwh = 2000
taxes and insurance o) 236 of
capital = 1600
total $5200
Level C
Capital Costs
settling pond area * 39 acres
pond costs - 60,000
polymer feed system - 5,000
thickener - 60,000
pump costs - 15,000
piping costs
total 155,000
total annual capital costs (10 years a 10%) = $25,200
Operating Costs
chemicals 11,000
maintenance S 536
of capital 7,800
power 2,000
taxes and insurance
a 236 of capital JLtlfifi
total 23,900
Cost Variances
Facilities surveyed for this subcategory have ages
from one to 20 years. There is no discernable correlation
of treatment costs with facility age.
Location. There was no discernable correlation of waste
water treatment costs with location.
Production capacities range from 54,000 to
900,000 kkg/yr (60,000 to 1,000,000 tons/yr) . Treatment
technology Levels A and B, involving pond costs, should show
slight unit cost variation (0.9 power). Level C technology
with a mechanical thickener as well as a pond are estimated
to be 0.7 exponential function of size. Operating costs
other than taxes, insurance and annualized capital costs are
estimated to be proportional to size.
217
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ACID AND ALKALINE FLOTATION
There are three types of flotation processes used for
removing impurities from industrial sands:
(1) Acid flotation to effect removal of iron oxide and
ilmenite impurities
(2) Alkaline flotation to remove aluminate bearing
materials, and
(3) Hydrofluoric acid flotation for removal of feldspar.
These three flotation processes have been subdivided into
two subcategories; (1) acid and alkaline flotation and
(2) hydrofluoric acid flotation, Subcategory (1) is
discussed in this subsection and subcategory (2) in the
following subsection.
Four surveyed acid flotation facilities have no effluent
discharge. The surveyed alkaline flotation facility has
effluent waste water similar in composition to the intake
stream. Recycle costs for acid and alkaline flotation waste
water are given in Table 19.
Cost Basis For Table 19
Basis: (1) production - 180,000 kkg/yr (200,000 tons/yr)
(2) the process waste water is treated with lime,
pumped to a holding pond and recirculated back to
the facility. The holding pond is one-half acre
and is cleaned once every ten years.
Capital costs
lime storage and feed system - 75,000
reaction tank - 40,000
pumps and piping * 20,000
agent
annualized capital cost (10 yr life d 1096) 22,000
Operating.Costs
chemical costs - 11,000
maintenance a) 5% of capital - 7,300
power - 2,000
taxes and insurance a) 2%
of capital - 2,900
total 23,200
218
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TABLE 19
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
COST
SUBCATEGORY Industrial Sand (acid and alkaline flotation)
PLANT SIZE 180,000
METRIC TONS PER YEAR.OF product
PLANT AGE 30 YEARS PLANT LOCATION southeastern U.S.
INVESTED CAPITAL COSTS!
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 a M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kq /metric ton of product }
Suspended Solids
RAW
WASTE
LOAD
100
LEVEL
A
(MIN)
115,000
18,700
19,000
1,000
38,700
0.22
0.4
B
135,000
22,000
21,200
2,000
45,200
0.25
0
C
D
E
LEVEL DESCRIPTION:
A— neutralize, settle, discharge
B — neutralize, settle, recycle
219
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Cost Variances
Age. Surveyed facilities in this subcategory ranged in age
from one to 60 years. There was no discernable correlation
between treatment costs and facility age.
Location. Most of the surveyed facilities are in
southeastern U.S. There was no discernable correlation
between treatment costs and facility location.
Size. Facilities in this subcategory range between 19,000
to 1,360,000 kkg/yr (54,000 to 1,500,000 tons/yr).
Costs/acre of small ponds change significantly with size.
Also, the chemical treatment facilities costs vary with size
at an estimated exponential rate of 0.6. Taken together,
capital costs are estimated to vary with size at 0.7
exponential rate. Operating costs, except for taxes,
insurance and other capital related factors may be expected
to vary directly with size.
HF FLOTATION
Unlike the acid and alkaline flotation processes where total
recycle is either presently utilized or believed to be
feasible, on the other hand, waste water from the HF
flotation process is of questionable quality for total
recycle. Estimated costs for partial recycle are given in
Table 20.
Cost Basis For Table 20
Basis: (1) production: 180,000 kkg/yr (200,000 tons/yr)
(2) all waste waters are fed to a thickener to
remove suspended materials. The overflow
containing 90 percent of the water is recycled to
the process, the underflow is fed to a settling
pond for removal of solid wastes and pH adjustment
prior to discharge.
220
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COST
TABLE 20
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SUBCATEGORY Industrie! Sand (HF Flotation)
PLANT SIZE 180,000 METRIC TONS PER YEAR OF product
California
PLANT AGE ~ YEARS
PLANT LOCATION
INVESTED CAPITAL COSTS:
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 3 M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kg/metric ton of product )
Suspended Solids
Fluoride
RAW
WASTE
LOAD
135
0.45
LEVEL
A
(MIN)
120,000
19,500
21,400
2,000
42,900
0.23
0.044
0.005
B
200,000
3^500
21,400
2,000
55,900
0.31
0
0
c
D
E
LEVEL DESCRIPTION:
A — 90% of wastewater removed in thickener and recycled to process. Underflow from
thickener fed to settling pond for removal of tailings and pH adjustment prior to
'discharge.
B'— segregate HF waste water, pond and evaporate; recycle other water after ponding.
221
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Capital Costs
pond - 1/2 acre x 10 ft depth d $20,000/acre * $ 10,000
lime storage and feed system - 30,000
thickener = 60,000
pump costs = 5,000
piping costs = 15,000
total 120,000
annualized investment costs (10 yr life d 10% interest)
$120,000 x .1629 = $19,500
Operating Costs
maintenance a) 5% of capital = 6,000
chemicals, lime & $20/ton = 11,000
power a $.02/kwh = 2,000
taxes and insurance a 2%
of capital = 2,400
total 23,400
Cost Variances
Age, location and size variances have no significance in .
this case since only one facility is involved.
.222
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GYPSUM
Gypsum is mined at sixty-five sites in the United States.
An estimated 57 of these facilities use no contact water, in
their process. It is estimated that 5 of the facilities use
wet scrubbers for dust removal, which results in a contact
water effluent. Two known facilities use heavy media
separation and washing to beneficiate the crude gypsum ore,
which results in a process effluent.
DRY PROCESS
There is no contact process water in this category, thus
there are no waste water treatment costs.
DRY PROCESS WITH USE OF WET SCRUBBERS
There are five facilities in this subcategory. Two are
presently using settling ponds. All five intend to install
dry scrubbers at some time in the future.
The scrubber water usage in two facilities in this
subcategory averages 2,505 1/kkg (598 gal/ton) of gypsum
produced. The effluent quality from these two facilities
averages 35 mg/1 with a pH of 7.8. One of the two
facilities impounds the water before discharge while the
second discharges without treatment. Present waste water
treatment costs for both are considered to be negligible.
The capital cost of a settling pond for such facilities is
$20,000.
A third facility in this subcategory uses 5,950 1/kkg
(1,427 gal/ton) of scrubber water with a suspended solids
concentration of 1,110 mg/1. This represents a substantial
increase in water usage and suspended solids load over the
previous two facilities. Present treatment consists of a
settling pond which removes fifty percent of the suspended
solids. The total annual cost for the settling pond was
reported as $2,500, which results in a cost of $0.01 per kkg
of gypsum produced. The company plans to replace the wet
scrubber system with a dry dust collector, which would
eliminate the waste stream. The capital investment for the
dry system was reported as $167,000, The annual capital
recovery for such a system would be $27,200 which results in
a cost of $0.14 per kkg of gypsum produced ($0.13/ton). All
gypsum producers contacted which use wet scrubbers indicated
that they plan to convert their systems to dry dust
collectors.
223
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HEAVY MEDIA SEPARATION
The third subcategory of wet processing of gypsum consists
of only two facilities. Both facilities presently have
effluent due to recycle of water after settling pond
treatment. In one of the facilities an abandoned mine is
utilized as the settling pond. Capital investment for the
system is estimated to be $15,000. Annual operating cost is
estimated to be $10,000. Total annualized recycle costs are
estimated to be $12,500. This results in a recycle cost of
$0.05 per kkg of gypsum produced ($0.045/ton).
MINE DRAINAGE
In all three of the subcategories of gypsum production, some
facilities find it necessary to pump out their quarries
because of rainwater collection. No facility is presently
treating its mine pumpout water, and the average effluents
are all below 25 mg/1, insofar as is known, so there is no
cost to treat the pit pumpout in this subcategory down to
this level, at least.
224
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ASPHALTIC MINERALS
Of the asphaltic minerals, bituminous limestone, oil-
impregnated diatomite and gilsonite, only gilsonite
operations currently have any discharge to surface water.
For gilsonite, present mine water drainage treatment
consists of pond settling of suspended solids prior to
discharge. Process water is discharged untreated. Costs
for present treatment are an estimated $0,08/kkg of
gilsonite produced ($0.07/ton).
Completion of treatment facilities currently under con-
struction will 'result in no discharge of waste water from
the property at a cost of $1,lO/kkg ($1/ton) of Gilsonite
produced. The cost estimates are given in Table 21.
Cost Variances
The only gilsonite facility is 50 years old and located in
Utah. All cost developments are for this specific facility.
Cost Basis For Table 21
Level A
Capital Costs
pond cost, $/hectare ($/acre): $24,700
($10,000)
settling pond area, hectares (acres): 0.8 (2)
pump, piping, ditching: $5,000
Operating and Maintenance Costs
taken as 2% of capital costs
Level B
Capital Costs
pond costs - same as Level A
sand filters - $150,000
pumps and piping - 40,000
electrical and
instrumentation 25,000
roads, fences, landscaping - 15,000
225
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COST
TABLE 21
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SUBCATE60RY Gilsonite
PLANT SIZE 45,450
PLANT AGE 50 YEARS
METRIC TONS PER YEAR OF Gilsonite
Utah
PLANT LOCATION
INVESTED CAPITAL COSTS!-
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 G M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON Gilsonite
WASTE LOAD PARAMETERS
Mine Pumpout:
Suspended Solids, me/liter
BOD, mg/liter
Process Water:
Suspended Solids, mg/Hte!
BOD, mg/liter
RA\V
V.'ASTE
LOAD
LEVEL
A
(MIN)
25,000
2,940
500
200
3,640
0.08
3,375
12
17
43
B
250,000
29,400
20,000
500
49,900
1.10
0
0
0
0
c
D
E
LEVEL
A — pond settling of suspended solids in.mine pumpout; no treotment of process water
(present minimum).
B — combining of mine pumpout ana process water followed by pond settling, filtration
and partial recycle. Discharge from recycle to be used .for on-property irrigation.
226
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Operating and Maintenance Costs
labor - 1/2 man 3 $10,000/yr $ 5,000
maintenance labor and materials
a U% of investment 10,000
power a $.01/kw-hr 500
taxes and insurance
3 2% of investment 5,000
227
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ASBESTOS
Asbestos is mined and processed at five locations in the
U.S., two in California, and one each in Vermont, Arizona
and North Carolina. One facility in California uses a wet
processing process, while the remaining four facilities use
a dry process. There is also one wollastonite dry facility
which has no process water. The wet process facility
process results in a discharge of twenty percent of the
process water (155,200 I/day; 41,000 gal/day) to two
pereolation/evaporation ponds. The ponds total less than
one half acre in size. The total capital investment for the
percolation ponds was estimated to be $2,000. Annual
operating and maintenance is estimated to be $1,000, The
total annualized cost is estimated to be $1,325, for the
percolation/evaporation ponds. One pond serves as an
overflow for the other, therefore, surface water discharge
almost never occurs. The ponds are dredged once annually.
Sixty-eight percent of tiae water in the wet process facility
is recycled via a three acre settling pond. A natural
depression is utilized for the pond, and dredging has been
not nece s sary. The water rec irculated amounts to
529,900 I/day (140,000 gal/day). Annualized cost for the
recirculation system is estimated to be $2,500. The
remaining twelve percent of the process water is lost in the
product and tailings. Total annualized water treatment
costs for wet processing of asbestos are estimated to be
$3,825, which results in a cost of $0.09/kkg of asbestos
produced ($0.08/ton).
All five operations accumulate waste asbestos tailings at
both facility and the mining site. These tailings are
subject to rainwater runoff. At two sites dams have been
built to collect rainwater and create
evaporation/percolation ponds. The total capital investment
at each site is estimated to be $500. Operating and
maintenance costs for these dams are considered to be
negligible. Natural canyons were utilized in both cases to
create the ponds. One facility because of its geological
location must discharge water collected in its mine. The
alkaline groundwater in the area requires the water to be
treated by addition of 0.02 mg/1 sulfuric acid before
discharge. The pumping costs for this operation are
considered to be part of the production process. The
chemical costs are considered to be less than $100/yr. The
total waste water treatment costs for pit pumpout water are
therefore considered to be negligible. The estimated
capital cost for total impoundment of mine water to
eliminate the discharge is $15,000,
228
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LIGHTWEIGHT AGGREGATE MINERALS
Lightweight aggregate minerals consist of perlite, pumice
and vermiculite.
PUMICE
All U.S. perlite facilities are in southwestern U.S. and the
processes are all dry. Since there is no water used, there
is no waste water generated or water treatment required.
One investigated mine does dewater the quarry when water ac-
cumulates, but this water is evaporated on land at estimated
cost of $0.01 to $0.05/kkg (or ton) of perlite produced.
PERLITE
At most facilities, there are no waterborne wastes as no
water is employed. At one facility there is scrubber water
from a dust control installation. The scrubber water is
sent to a settling pond prior to discharge. Because of the
relatively small amount of water involved and the large
production volume of pumice per day, treatment costs for
this one facility are roughly estimated as less than
$0.05/kkg (or ton) of pumice produced at that facility.
VERMICULITE
The two facilities described in Section V represent total
capacity appraching the total U.S. production. Both of
these facilities currently achieve no discharge of
pollutants by means of recycle, pond evaporation and
percolation. Detailed costs for a typical facility are
given in Table 22.
cost Variance
The ages of the two facilities are 18 and 40 years,
Age is not a cost variance factor.
Location. One facility is located in Montana and the other
in South Carolina. In spite of their different geographical
location, both are able to achieve no discharge of
pollutants by the same general means and at roughly
equivalent costs.
Size. Facility sizes range from 109,000 to 209,000 kkg/yr
(120,000 to 230,000 tons/yr). Since pond costs per acre are
virtually constant in the size range involved, waste water
treatment costs may be considered directly proportional to
facility size and therefore invariant on a cost/ton of
product basis.
229
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COST
TABLE 22
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SUBCATEGORY VermicuMte
PLANT SIZE 160,000
PLANT AGE 30 YEARS
METRIC TONS PER YEAR OF product
PLANT LOCATION Montana or South Carolina
INVESTED CAPITAL COSTS:.
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 a M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND PO'.YER
TOTAL ANNUAL COSTS
COST/METRIC TON product
WASTE LOAD PARAMETERS
(kg/metric ton of product )
Suspended Solids
RAW
WASTE
LOAD
1,600
LEVEL
A
(MiN)
325,000
5^900
40,000
5,000
97,900
0.62
0
B
C
D
E
LEVEL
A — recycle, evaporation and percolation,
230
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Cost Basis For Table 22
Capital and operating costs were taken from industry
reported values. The basis of these values is shown below:
Assumptions:
Production:
Process Water Use;
Treatment:
Capital Cost:
Operating Costs:
Annual Capital
Recovery:
157,000 kkg/yr (175,000 tons/yr)
8,350 1/kkg (2,000 gal/ton)
settling ponds and recycle of
process water
$325,000
$ 45,000/yr
$ 52,900
231
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MICA
There are seven significant wet mica beneficiation
facilities in the U.S., six dry grinding facilities
processing beneficiated mica, and three wet grinding
facilities.
There are also several western U.S. operations using dry
surface mining. They have only some mine water drainage.
Treatment for this mine water is estimated as $0.19/kkg
($0.2/ton) (based on a 1/2 acre pond 3> $10,0QO/acre and
operating costs of $750/yr).
WET BENEFICIATION PLANTS
Eastern U.S. beneficiation facilities start with matrices of
approximately 10 percent mica and 90 percent clay, sand, and
feldspar combinations. Much of this 90 percent is converted
to saleable products, but there is still a heavy portion
which must be stockpiled or collected in pond bottoms. The
variable nature of the ore, or matrix, leads to several
significant treatment/cost considerations:
(1) Treatment costs and effluent quality differ from
facility to facility,
(2) Additional saleable products reduce the cost impact of
the overall treatment systems developed.
(3) solids disposal costs are often a major portion of the
overall treatment costs, particularly if they have to be
hauled off the property.
All of these factors can change the overall treatment costs
per unit of product of Table 23 by at least a factor of two
in either direction.
Cost Variances
Age. Known ages for four of the seven facilities range from
18 to 37 years. There is no significant treatment cost
variance due to this range.
Location. All facilities are located in southeastern states
in rural locations. Location is not a significant cost
variance factor.
Size. The sizes range from 13,600 to 34,500 kkg/yr (1,500
to 3,800 tons/yr). The unit costs given are meant to be
representative over this size range on a unit production
basis.
232
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COST
TABLE 23
FOR A REPRESENTATIVE PLANT
(ALL COSTS ARE CUMULATIVE)
SU3CATEGORY Mica/ Wet Beneficiation (eastern)
PLANT SIZE 16,360
PLANT AGE 27 YEAftS
METRIC TONS PER YEAR.OF Mica
PLANT LOCATION,
Southeastern U.S.
INVESTED CAPITAL COSTS:
TOTAL
ANNUAL CAPITAL RECOVERY
OPERATING AND MAINTENANCE
COSTS:
ANNUAL 0 Q M (EXCLUDING
POWER AND ENERGY)
ANNUAL ENERGY AND POWER
TOTAL ANNUAL COSTS
COST/METRIC TON Mica
WASTE LOAD PARAMETERS
(kg /metric ton of Mica )
.Suspended Solids
pH
RAW
WASTE
LOAD
2,100
—
LEVEL
A
(MiN)
150,000
17,600
50,000
2,000
.69,600
4.3
2.5-6
6-9
B
275,000
32,300
64,500
3,000
99,800
6.1
1.2-2.5
6-9
C
300,000
35,200
68,000
5,000
108,200
6.6
0
-
D
245,00.0
39,900
74,400
5,000
119,300
7.3
1.2-2.5
6-9
E
245,000
39,900
74,400
5,000
119,300
7.3
0
-
LEVEL
A — minimum level ponding
B — extended ponding and chemical treatment
C — closed cycle pond system (no discharge)
D — mechanical thickener and filter
E — closed cycle thickener and filter system (no discharge)
233
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Cost Basis For Table 23
Treatment Level A - Pond settling of process wastes (minimum
treatment)
Basis:
(1)
(2)
(3)
W
(5)
Production rate - 16
ton/yr)
Solid wastes ponded -
ton/yr)
Solid waste stockpiled
ton/yr)
Pond size - 4 hectares
Effluent quality
,400 kkg/yr
34,200 kkg/yr
- 45,000 kkg/yr
(10 acres)
(18,000
(38,000
(50,000
(a) suspended solids - 20-50 mg/1
(b) pH - 6-9
(6)
Waste water effluent - 5.7 x
mgd)
10* I/day (1.5
Capital.costs
Ponds =
Pumps and piping -
Miscellaneous constructions =
Total
Assume 20 yr life and 10% interest
capital recovery factor = .1174
$100,000
35,000
15.000
$150,000
Annual investment costs
Operating Costs
= $17,610/yr
Solid wastes handling a $0.30/ton = $15,000
Pond cleaning d $0.50/ton = 19,000
Maintenance \ = 10,000
Power = 2,000
Labor = 3,000
Taxes and insurance a 2% of
capital = 3,000
Total $52,000
234
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Treatment Level B - Pond settling of process wastes and
chemical treatment
Basis: Same as for Level A, except
(1) Pond size - 8 hectares (20 acres)
(2) Chemical treatments - lime, acid and
flocculating agents used as needed
(3) Effluent quality
(a) suspended solids - 10-20 ing/1
(b) pH - 6-9
Capital Costs
Ponds = $200,000
Pumps and piping = 50,000
Miscellaneous construction = 25,000
Total $275,000
Annual investment costs = $32,285/yr
Operating Costs
Solid wastes handling d $0.30/ton = $15,000
Pond cleaning 3 $0.50/ton = 19,000
Maintenance = 15,000
Chemicals = 5,000
Power = 3,000
Labor (misc) = 5,000
Taxes and insurance 3) 2%
of capital = 5,500
Total $67,500
Treatment Level c - Total recycle of process water using,
pond system
Basis: Same as Level B except no discharge
Capital Costs
Ponds = $200,000
Pumps and piping = 75,000
Miscellaneous construction = 25,000
Total $300,000
Annual investment costs = $35,220
235
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Opera-ting Costs
Solids wastes handling 3 $0.30/ton = $15,000
Pond cleaning d $0.50/ton = 19,000
Maintenance = 20,000
Chemicals = 5,000
Power = 5,000
Labor = 3,000
Taxes and insurance d 2% of
capital = 6^000
Total $73,000
Treatment Level D - Thickener plus filter removal of
suspended solids. Generally pond systems are the preferred
system for removing suspended solids from waste water. In
some instances, however, when the land for ponds is not
available or there are other reasons for compactness,
mechanical thickeners, clarifiers, and filters are used.
Basis: Same as for Level B, except no pond required
Capital costs
Thickener - 15 meter (50 ft.) diameter = $150,000
Filter system installed = 35,000
Pumps, tanks, piping, collection = 50,000
Conveyor = 5,000
Building = 5^.000
Total $245,000
At 10 yr life and 10% interest rate
Capital recovery factor = .1627
Annual investment costs = $39,862
Operating Costs
Solids wastes handling d $0.30/ton = $26,400
Maintenance = 20,000
Chemicals = 20,000
Power = 5,000
Labor = 3,000
Taxes and insurance a 2%
of capital = 5,000
Total $79,400
236
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Treatment Level E - Thickener and filter removal of
suspended solids and recycle to eliminate discharge.
Basis: same as for Level D, complete recycle of treated
wastes
Capital Costs
Same as for Level D - pumping and piping to surface
water discharge taken as same as recycle piping and
pumping.
Operating Costs
Same as for Level D
Total annual costs = $119,300
DRY GRINDING PLANTS
There are no waterborne wastes from this subcategory.
WET GRINDING PLANTS
Of the three facilities involved, one sends its small amount
of wast^ water to nearby waste treatment facilities of much
larger volume, the second has no waterborne waste due to the
nature of its process and the third uses a settling pond to
remove suspended solids prior to water recycle. Total costs
for waste water treatment from this third operation are
estimated as $2.60/kkg of wet ground mica produced
($2.30/ton). A capital investment of $65,000 is required.
237
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-------
SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
INTRODUCTION
The effluent limitations which must be achieved by July 1,
1977, are based on the degree of effluent reduction attain-
able through the application of the best practicable control
technology currently available. For the mining of minerals
for the construction industry, this level of technology was
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, this
segment of the minerals mining and processing industry was
divided into nine 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 limitations
guidelines and standards of performance.
Best practicable control technology currently available
emphasizes treatment facilities at the end of a
manufacturing 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 were considered normal practice
within these industries are:
(a) manufacturing process controls;
(b) recycle and alternative uses of water; and
(c) recovery and/or reuse of some waste water 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;
(c) the process employed;
(d) the engineering aspects of the application of various
types of control techniques;
(e) process changes; and
(f) non-water quality environmental impact (including energy
requirements).
239
-------
The following is a discussion of the best practicable
control technology currently available for each of the
subcategories, and the proposed limitations on the
pollutants in their effluents.
GENERAL WATER GUIDELINES
Process Water
Process water is defined as any water contacting the ore,
processing chemicals, intermediate products, by-products 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.
Process generated waste water is defined as any water which
in the mineral processing operations such as crushing,
washing and beneficiation, comes into direct contact with
any raw material, intermediate product, by-product or
product used in or resulting from the process.
Where sufficient data was available a statistical analysis
of the data was performed to determine a monthly and a daily
maximum. In most subcategories, where there is an allowable
discharge, an achievable monthly maximum was determined from
the data available.
A detailed analysis of the ratio of daily TSS to monthly TSS
maximum at a 99 percent level of confidence for large
phosphate slime ponds indicates that a TSS ratio of 2.0 is
representative of a large settling pond treatment system,
and this ratio was used where there was insufficient data to
predict a daily maximum directly.
A ratio of 2.0 was also used for parameters other than TSS.
It is judged that this is an adequate ratio since the
treatment systems for F, Zn and Fe for instance have
controllable variables, such as pH and amount of lime
addition. This is in contrast to a pond treating only TSS
which has few if any operator controllable variables.
Cooling Water
In the minerals mining and processing 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
technology currently available, the recommendations for the
discharge of such cooling water are as follows:
240
-------
An allowed discharge of all non-con-tact cooling waters pro-
vided that the following conditions are met:
(a) Thermal pollution be in accordance with EPA standards.
Excessive thermal rise in once through non-contact
cooling water in the mineral mining industry has not
been a significant problem.
(b) All non-contact cooling waters should be monitored to
detect leaks of pollutants from the process. Provisions
should be made for treatment to the standards
established for process waste water 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 as a separate category.
Mine Drainage
Mine drainage is any water drained, pumped or siphoned from
a mine.
Storm Water Runoff
Untreated overflow may be discharged from process waste
water or mine drainage impoundments without limitation if
the impoundments are designed, constructed and operated to
contain all process generated waste water or mine drainage
and surface runoff into the impoundments resulting from a 10
year 24 hour precipitation event as established by the
National Climatic Center, National Oceanic and Atmospheric
Administration for the locality in which such impoundments
are located. To preclude unfavorable water balance
conditions resulting from precipitation and runoff in
connection with tailing impoundments, diversion ditching
should be constructed to prevent natural drainage or runoff
from mingling with process waste water or mine drainage.
WASTE WATER GUIDELINES AND LIMITATIONS
DIMENSION STONE
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
241
-------
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of dimension stone is ponding and
recycle of process water. To implement this technology at
facilities not already using the recommended control
techniques would require the improvement of suspended solids
settling and the installation of recycle equipment. At
least seven facilities representing all the major types of
stone presently achieve the recommended limits. Four
facilities were cited in Section V as applying total recycle
of process waste water.
CRUSHED STONE (DRY)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated generated waste water
pollutants because no process water is used.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
CRUSHED STONE (WET)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
242
-------
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of crushed stone by the wet
process is recycle of process waste water. To implement
this technology at facilities not already using the
recommended control techniques would require the
installation of pumps and associated recycle equipment.
Approximately one third of the facilities studied presently
use the recommended technology.
CRUSHED STONE (FLOTATION PROCESS)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of crushed stone by the flotation
process is recycle of all process water to the wet process
washing step. To implement this technology at facilities
not already using the recommended control techniques would
require the installation of pumps and associated recycle
equipment. This technology is already employed in at least
two facilities in this subcategory.
CONSTRUCTION SAND AND GRAVEL (DRY)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process water is used.
243
-------
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaiminated runof.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
CONSTRUCTION SAND AND GRAVEL (WET)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage.
Effluent characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of construction sand and gravel by
the wet process is ponding and/or recycle of all process
waste water. To implement this technology at facilities not
already using the recommended control techniques would
require installation of ponds where necessary and plumbing
and piping for recycling. More than half the subcategory is
presently using the recommended technologies.
CONSTRUCTION SAND AND GRAVEL (DREDGING WITH LAND PROCESSING)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
from the -land based operations where the process water
intake does not originate from the dredge pump. No limits
are proposed for dredges and dredge pumpage water pending
further investigation of this subcategory.
Based upon the data in Section V the following limits can be
achieved for process contaiminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
244
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Best practicable control technology currently available for
the mining and processing of construction sand and gravel by
the dredging process with land processing is ponding and/or
recycle of all non-dredge pumped process waste water.
To implement this technology at facilities not already using
the recommended control techniques would require
installation of ponds, if necessary, and pumping and piping
for recycling.
More than half this subcategory is presently achieving this
level of technology for on-land treatment.
INDUSTRIAL SAND (DRY PROCESS)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of industrial sand by the dry
process is the recycle of air pollution control scrubber
water, where wet scrubbers are used. There is no water used
in the processing of this mineral. To implement this
technology at facilities not already using the recommended
control techniques would require the installation of pumps,
piping, and tanks for scrubber recycle, where wet scrubbers
are used. This technology is employed by at least one
facility in this subcategory.
INDUSTRIAL SAND (WET PROCESS)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
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Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of industrial sand by the wet
process is settling of suspended solids by means of
mechanical equipment and/or ponds and complete recycle of
process water. To implement this technology at facilities
not already using the recommended control techniques would
require the installation of adequate settling equipment
and/or ponds and recycle equipment* Three of the four
facilities surveyed presently utilize the recommended
technologies.
INDUSTRIAL SAND (ACID AND ALKALI FLOTATION PROCESS)
Based upon the information contained in Sections ill through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of industrial sand by the acid and
alkali flotation processes is the settling of suspended
solids in ponds using flocculants where necessary,
adjustment of pH where necessary and/or recycle of process
water. To implement this technology at facilities not
already using the recommended control techniques would
require the installation of pumps, piping and other
necessary recycle equipment. Four of the five facilities
studied are currently meeting the recommended limitation by
utilizing these technologies.
INDUSTRIAL SAND (HF FLOTATION PROCESS)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
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effluent reduction attainable through the application of the
best practicable control technology currently available is:
Effluent Limitation
kq/kkg
Effluent fib/1000 Ib) of product
Characteristic Monthly Average Daily_Maximum
TSS O.OU4 0.088
fluoride 0.005 0.01
The above limitations were based on the average performance
of the only facility in this subcategory.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff,
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of industrial sand by the HF
flotation process is thickening, ponding to settle suspended
solids, pH adjustment and partial recycle of process water.
The only facility in bhis subcategory presently uses the
recommended technologies.
GYPSUM (DRY)
Based upon the information contained in Sections III through
VIII, a determination has been made that -the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no- discharge of process .generated waste water pollutanrs
because no process water is used.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
GYPSUM (WET SCRUBBING)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is:
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Effluent Limitation
kg/kkg
of product
Effluent Characteristic Monthly Average Daily Maximum
TSS 0.13 0.26
The above limitations were based on the performance
demonstrated at facilities employing wet scrubbers for dust
collection.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of gypsum using wet scrubbing is
settling of suspended solids by ponds or mechanical
equipment. To implement this technology at facilities not
already using the recommended control techniques would
require the installation of solids settling equipment or
ponds.
This technology is already employed by facilities in this
subcategory.
GYPSUM (HEAVY MEDIA SEPARATION)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of gypsum by the heavy media
separation process is recovery of heavy media, settling of
suspended solids, and total recycle of process water. This
technology is used at both facilities in this subcategory.
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ASPHALTIC MINERALS (BITUMINOUS LIMESTONE)
Based upon the information contained in Sections III through
VIIIw a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process waste water is used.
ASPHALTIC MINERALS (OIL IMPREGNATED DIATOMITE)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Best practiclable control technology currently available for
the mining and processing of oil impregnated diatomite is
the recycle of scrubber water. There is no water used in
the processing of this material.
The one facility in this subcategory presently uses the
recommended technology.
ASPHALTIC MINERALS (GILSONITE)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Best practicable control technology currently available for
the mining and processing of gilsonite is ponding, settling
and partial recycle of water.
There is only one facility in this subcategory and this
facility presently uses the recommended technologies.
ASBESTOS (DRY PROCESS)
Based upon the information contained in sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no water is used in the process.
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Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent characteristic
Effluent Limitation
Daily Maximum
TSS
30 mg/1
ASBESTOS (WET)
Based upon the information contained in Sections III through
VIII* a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic
TSS
Effluent Limitation
Daily Maximum
30 mg/1
Best practicable control technology currently available for
the mining and processing of asbestos by the wet process is
total impoundment of all process waste waters.
The techniques described are
facility in this subcategory.
currently used by the only
WOLLASTONITE
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process water is used.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic
TSS
Effluent Limitation
Daily Maximum
30 mg/1
LIGHTWEIGHT AGGREGATE MINERALS (PERLITE)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
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effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process water is used.
LIGHTWEIGHT AGGREGATE MINERALS (PUMICE)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process water is used.
LIGHTWEIGHT AGGREGATE MINERALS (VERMICULITE)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Best practicable control technology currently available for
the mining and processing of vermiculite is ponding to
settle suspended solids, clarification with flocculants if
needed, and recycle of water to process.
The two major facilities producing vermiculite presently use
the recommended technologies.
MICA AND SERICITE (DRY PROCESS)
Based upon the information contained in Sections III through
VIII, a. determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants
because no process water is used.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
MICA (WET GRINDING PROCESS)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
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best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of mica by the wet grinding
process is settling of suspended solids and recycle of
clarified water to process. To implement this technology at
facilities not already using the recommended control
techniques would require the installation of settling tanks
and/or ponds and recycle equipment. One of the three
facilities in this subcategory utilizes the recommended
technologies.
MICA (WET BENEFICIATION PROCESS, EITHER NON-CLAY OR
GENERAL PURPOSE CLAY BY-PRODUCT)
Based upon the information contained in Sections III through
VIII, a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is
no discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of mica by the wet beneficiation
process where either no clay or general purpose clay is the
by-product is settling of suspended solids in ponds and
recycle of process water. Four of the five facilities in
this subcategory are presently using the recommended
technologies,
MICA (WET BENEFICIATION PROCESS, CERAMIC GRADE CLAY BY-PRODUCT)
Based upon the information contained in Sections III through
VIIIt a determination has been made that the degree of
effluent reduction attainable through the application of the
best practicable control technology currently available is:
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Effluent, Limitation
kg/kkg of product (Ibs/lOOO'lb)
Effluent Characteristic Monthly Average Daily Maximum
TSS 1.5 3.0
The above limitations are based on the performance of two
facilities,
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best practicable control technology currently available for
the mining and processing of mica by the wet beneficiation
process where ceramic grade clay is the by-product is
settling of suspended solids in ponds and lime treatment for
pH adjustment prior to discharge. Both facilities in this
subcategory are presently using the recommended
technologies.
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SECTION X
EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST AVAILABLE
TECHNOLOGY ECONOMICALLY ACHIEVABLE
INTRODUCTION
The effluent limitations which must be achieved by July 1,
1983 are based on the degree of effluent reduction attain-
able through the application of the best available tech-
nology economically achievable. For the mining of minerals
for the construction 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 where it is readily
transferable from one industry process to another. In
Section IV, this segment of the mineral mining and proces-
sing industry was divided into nine major categories based
on similarities of process. 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.
The following factors were taken into consideration in
determining the best available technology economically
achievable:
(1) the age of equipment and facilities involved;
(2) the process employed;
(3) the 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) non-water quality environmental impact (including energy
requirements).
In contrast to the best practicable 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 the following:
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(1) alternative water uses
(2) water conservation
(3) waste stream segregation
(4) water reuse
(5) cascading water uses
(6) by-product recovery
(7) reuse of waste water constituents
(8) waste treatment
(9) good housekeeping
(10) preventive maintenance
(11) quality control (raw material, product, effluent)
(12) monitoring and alarm systems.
Those facility processes and control technologies which at
the pilot facility, 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 available 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 III 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 control technology economically
achievable in the various subcategories of the mineral
mining and processing industry.
Storm Water Runoff
Untreated overflow may be discharged from process waste
water or mine drainage impoundments without limitation if
the impoundments are designed, consturcted and operated to
contain all process generated waste water or mine drainage
and surface runoff into the impoundments resulting from a 25
year 24 hour precipitation event as established by the
National Climatic Center, National Oceanic and Atmospheric
Administration for the locality in which such impoundments
are located. To preclude unfavorable water balance
conditions resulting from precipitation and runoff in
connection with tailing impoundments, diversion ditching
should be constructed to prevent natural drainage or runoff
from mingling with process waste water or mine drainage.
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PROCESS WASTEWATER GUIDELINES AND LIMITATIONS,
NO DISCHARGE GROUP
The following industry subcategories were required to
achieve no discharge of process generated waste water
pollutants to navigable waters based on best practicable
control technology currently available:
dimension stone
crushed stone (dry)
crushed stone (wet)
crushed stone (flotation)
construction sand and gravel (dry)
cons-turction sand and gravel (wet)
construction sand and gravel (dredging with land
processing)
industrial sand (dry)
industrial sand (wet)
industrial sand (acid and alkaline flotation)
gypsum (dry)
gypsum (heavy media separation)
bituminous limestone
oil impregnated diatomite
gilsonite
asbestos (dry)
asbestos (wet)
wollastonite
perlite
pumice
vermiculite
mica and sericite (dry)
mica (wet, grinding)
mica (wet beneficiation, either no clay or
general purpose clay by-product)
The same limitations guidelines are recommended based on
best available technology economically achievable.
INDUSTRIAL SAND (HF FLOTATION)
Based upon the information contained in Sections III through
IX, a determination has been made that the degree of
effluent reduction attainable through the application of the
best available technology economically achievable is no
discharge of process generated waste water pollutants.
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Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best available technology economically achievable for the
mining and processing of industrial sand by the HF flotation
process is thickening, ponding to settle suspended solids,
pH adjustment and total recycle of process water after
segregation and total impoundment of the HF-containing
segment of the process waste stream. To implement this
technology at the one facility would require the
installation of an impoundment pond and necessary piping.
This facility is located in an arid region and should be
able to totally impound the HF-containing portion of its
waste stream and recycle the remainder.
GYPSUM (WET SCRUBBING)
Based upon the information contained in Sections III through
IX, a determination has been made that the degree of
effluent reduction attainable through the application of the
best available technology economically achievable is no
discharge of process generated waste water pollutants.
Based upon the data in Section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best available technology economically achievable for the
mining and processing of gypsum by, the wet scrubbing process
is the elimination of wet scrubbers by dry collection
methods or total impoundment of scrubber water. To
implement this technology at facilities not already using
the recommended control techniques would require the
installation of dry collection apparatus or impoundments for
scrubber water. All the facilities presently using wet
scrubbers have stated their intention to convert to dry
collection methods.
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MICA (WET BENEFICIATION PROCESS, CERAMIC GRADE
CLAY BY-PRODUCT)
Based upon the information contained in Sections III through
IX, a determination has been made that the degree of
effluent reduction attainable through the application of the
best available technology economically achievable is:
Effluent Limitation
Effluent Characteristic Monthly Average Daily Maximum
TSS 1-25 2,5
The above limitations were based on the performance at one
facility.
Based upon the data in section V the following limits can be
achieved for mine drainage and process contaminated runoff.
Effluent Characteristic Effluent Limitation
Daily Maximum
TSS 30 mg/1
Best available technology economically achievable for the
mining and processing of mica by the wet beneficiation
process where ceramic-grade clay is the by-product, is
improved settling of suspended solids in ponds and lime
treatment for pH adjustment prior to discharge. One of the
two facilities in this subcategory is presently achieving
the recommended level,
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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-facility 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 of
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) the 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 recoverable solvents from water); and
f) recovery of pollutants as by-products.
In addition to the effluent limitations covering discharges
directly into waterways, the constituents of the effluent
discharge from a facility within the industrial category
which would interfere with, pass through, or otherwise be
incompatible with a well designed and operated publicly
owned activated sludge or trickling filter waste water
treatment facility were identified. A determination was
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made of whether the introduction of such pollutants into the
treatment facility should be completely prohibited.
GENERAL WATER GUIDELINES
The process water, cooling water, mine water pumpout, and
blowdown guidelines for new sources are identical to those
based on best available technology economically achievable.
PROCESS WATER GUIDELINES
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
subcategories of the minerals for the construction industry
segment of the mineral mining and processing industry.
Storm Water Runoff
Untreated overflow may be discharged from process waste
water or mine drainage impoundments without limitation if
the impoundments are designed, consturcted and operated to
contain all process generated waste water or mine drainage
and surface runoff into the impoundments resulting from a 25
year 24 hour precipitation event as established by the
National Climatic Center, National Oceanic and Atmospheric
Administration for the locality in which such impoundments
are located. To preclude unfavorable water balance
conditions resulting from precipitation and runoff in
connection with tailing impoundments, diversion ditching
should be constructed to prevent natural drainage or runoff
from mingling with process waste water or mine drainage.
The following industry subcategories were required to
achieve no discharge of process generated waste water
pollutants to navigable waters based on best practicable
control technology currently available;
dimension stone
crushed stone (dry)
crushed stone (wet)
crushed stone (flotation)
construction sand and gravel (dry)
construction sand and gravel (wet)
construction sand and gravel (land processing)
industrial sand (dry)
industrial sand (wet)
industrial sand (acid and alkaline flotation)
gypsum (dry)
gypsum (heavy media separation)
bituminous limestone
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oil impregnated diatomite
gilsonite
asbestos (dry)
asbestos (wet)
wollastonite
perlite
pumice
vermiculite
mica and sericite (dry)
mica (wet, grinding)
mica (wet beneficiation, either no clay or
general purpose clay by-product)
The same limitations guidelines are recommended based on
best available technology economically achievable,
The following industry subcategories were required to
achieve no discharge of process generated waste water
pollutants to navigable waters based on best available
technology economically achievable:
industrial sand (HF flotation process)
gypsum (wet scrubbing)
The same limitations are recommended as new source
performance standards.
The following industry subcategories are required to achieve
specific effluent limitations as given in the following
paragraphs.
MICA (WET BENEFICIATION, CERAMIC
GRADE CLAY BY-PRODUCT)
Same as best available technology economically achievable.
PRETREATMENT STANDARDS
Recommended pretreatment guidelines for discharge of
facility waste water 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" a subsequent
EPA publication. The following definitions conform to these
publications:
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a, 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 4.1
Prohibited Wastes.
b. Incompatible Pollutant
The term "incompatible pollutant" means any pollutant which
is not a compatible pollutant as defined above.
c. Joint Treatment Works
Publicly owned treatment works for both non-industrial and
industrial waste water.
d. Major Contributing Industry
A major contributing industry is an industrial user of the
publicly owned treatment works that: has a flow of 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 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,
e. Pretreatment
Treatment of waste waters from sources before introduction
into the joint treatment works.
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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.
Recommended Pretreatment Guidelines
In accordance with the preceding Pretreatment standards for
Municipal Sewer Works, the following are recommended for
Pretreatment Guidelines for the waste water effluents:
a. No pretreatment required for removal of compatible
pollutants - biochemical oxygen demand, suspended solids
(unless hazardous), pH, and fecal coliform bacteria;
b. Suspended solids containing hazardous pollutants such as
heavy metals, cyanides and chromates should conform to
be restricted to those quantities recommended in
Section IX Guidelines for Be st Practi cal Control
Technology Currently Available for existing sources and
new sources performance standards for new sources;
c. Pollutants such as chemical oxygen demand, total organic
carbon, phosphorus and phosphorus compounds, nitrogen
and nitrogen compounds, and fats, oils, and greases,
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need not be removed provided the publicly owned
treatment works was designed to treat such pollutants
and will accept them. Otherwise levels should be at
best practicable control technology currently available
recommendations for existing sources and at new source
performance standards recommendations for new sources;
d. Limitation on dissolved solids is not recommended except
in cases of water quality violations.
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SECTION XII
ACKNOWLEDGEMENTS
The preparation of this report was accomplished through the
efforts of the staff of General Technologies Division,
Versar, Inc., Springfield, Virginia, under the overall
direction of Dr. Robert G. Shaver, Vice President. Mr.
Robert C. Smith, Jr., Chief Engineer, Project Office,
directed the day-to-day work on the program,
Mr. Michael W. Kosakowski was the EPA Project Officer. Mr.
Allen Cywin, Director, Effluent Guidelines Division, Mr.
Ernst P. Hall, Jr., Assistant Director, Effluent Guidelines
Division, and Mr. Harold B. Coughlin, Branch Chief, Effluent
Guidelines Division, offered many helpful suggestions during
the program. Mr. Ralph Lorenzetti assisted in many facility
inspections.
Acknowledgement and appreciation is also given to Linda Rose
and Darlene Miller (word processors) of the Effluent
Guidelines Division and the secretarial staff of the General
Technologies Division of Versar, Inc., for their efforts in
the typing of drafts, necessary revisions, and final
preparation of the effluent guidelines document.
Appreciation is extended to the following trade associations
and state and federal agencies for assistance and
cooperation rendered to us in this program:
American Mining Congress
Asbestos Information Association, Washington, D.C.
Barre Granite Association
Brick Institute of America
Building Stone Institute
Fertilizer Institute
Florida Limerock Institute, Inc.
Florida Phosphate Council
Georgia Association of Mineral Processing Industries
Gypsum Association
Indiana Limestone Institute
Louisiana Fish and Wildlife Commission
Louisiana Water Pollution Control Board
Marble Institute of America
National Clay Pipe Institute
National Crushed Stone Association
National Industrial Sand Association
National Limestone Institute
National Sand and Gravel Association
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New York State Department of Environmental conservation
North Carolina Minerals Association
North Carolina Sand, Gravel and Crushed Stone Association
Portland Cement Association
Refractories Institute
Salt Institute
State of Indiana Geological Survey
Texas Water Quality Board
U.S. Bureau of Mines
U.S. Fish and Wildlife Service, Lacrosse, Wisconsin
Vermont Department of Water Resources
Appreciation is also extended to the many mineral mining and
producing companies who gave us invaluable assistance and
cooperation in this program.
Also, our appreciation is extended to the individuals of the
staff of General Technologies Division of Versar, Inc., for
their as si stance during thi s program. Speci fi cally, our
thanks to:
Dr. R. L. Durfee, Senior Chemical Engineer
Mr. D. H. Sargent, Senior Chemical Engineer
Mr. E. F. Abrams, Chief Engineer
Mr. L. C. McCandless, Senior Chemical Engineer
Dr. L. C. Parker, Senior Chemical Engineer
Mr. E. F. Rissman, Environmental Scientist
Mr. J. C. Walker, Chemical Engineer
Mrs. G. Contos, Chemical Engineer
Mr. M. W. Slimak, Environmental Scientist
Dr. I. Frankel, Chemical Engineer
Mr. M. DeFries, Chemical Engineer
Ms. C. V. Fong, Chemist
Mrs. D. K. Guinan, Chemist
Mr. J. G. Casana, Environmental Engineer
Mr. R. C, Green, Environmental Scientist
Mr. R. S. Wetzel, Environmental Engineer
Ms. M.A. Connole, Biological Scientist
Ms* M. Smith, Analytical Chemist
Mr. M. C, Calhoun, Field Engineer
Mr. D. McNeese, Field Engineer
Mr. E. Hoban, Field Engineer
Mr. P. Nowacek, Field Engineer
Mr. B. Ryan, Field Engineer
Mr. R. Freed, Field Engineer
Mr. N. O. Johnson, Consultant
Mr. F. Shay, Consultant
Dr. L. W. Ross, Chemical Engineer
Mr. J. Boyer, Chemical Engineer
268
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SECTION XIII
REFERENCES
1. Agnello, L., "Kaolin", Industrial and Engineering
Chemistry,Vol* 52, No. 5, May 1960, pp. 370-376.
2. "American Ceramic Society Bulletin," Vol. 53, No. 1,
January 1974, Columbus, Ohio.
3. Arndt, R.H., "The Shell Dredging Industry of the Gulf
Coast Region," U.S. Department of the Interior, 1971.
4. Bates, R.Ii,, Geology of the Industrial Rocks and
Minerals,Dover Publications, Inc., New York, 1969.
5. Beeghly, J.H., "Water Quality and the Sand and Gravel
Industry," 37th Annual Meeting Ohio Sand and Gravel
Association, 1971.
6. Boruff, C.S., "Removal of Fluorides from Drinking
Waters," Industrial and Engineering Chemistry. Vol. 26,
No. 1, January 1934, pp. 69-71.
7. Brooks, R.G., "Dewatering of Solids," 57th Annual
Convention National Crushed Stone Association, 1974.
8. Brown, W.E., U.S. Patent 2,761,835, September 1956.
9. Brown, W.E., and Gracobine, C.R., U.S. Patent 2,761,841,
September 1956.
10. "Census of Minerals Industries," 1972, Bureau of the
Census, U.S. Department of Commerce, U.S. Government
Printing Office, Washington, D.C. MIC72 (PJ-14A-1 through
MIC72(P)-14E-4.
11. "Commodity Data Summaries, 1974, Appendix I to Mining
and Minerals Policy," Bureau of Mines, U.S. Department
of the Interior, U.S. Government Printing office,
Washington, D.C.
12. Davison, E.K,, "Present status of Water Pollution
Control Laws and Regulations," 57th Annual Convention
National Sand and Gravel Association, 1973.
13. Day, R.W., "The Hydrocyclone in Process and Pollution
Control," Chemical Engineering Progress, Vol. 69, No. 9,
1973, pp. 67-72.
269
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14. "Dictionary of Mining, Mineral, and Related Terms,"
Bureau of Mines, D.S. Department of the Interior, U.S.
Government Printing Office, Washington, D.C., 1968.
15. "Engineering and Mining Journal," McGraw-Hill, October
1974.
16, Groom, F., "Vacuum Filtration - An Alternative to the
Use of Large Settling Ponds in Sand and Gravel
Production," National Sand and Gravel Association
Circular No. 117.
17. Haden, W., Jr., and Schwint, I., "Attapulgite, Its
Properties and Applications," Industrial and Engineering
Chemistry, Vol. 59, No. 9, September 1967, pp. 57-69.
18. "Indiana Limestone Handbook," Indiana Limestone
Institute of America, Inc., January 1973, Bedford,
Indiana.
19. Krenkel, P.A., "Principles of Sedimentation and
Coagulation As Applied to the Clarification of Sand and
Gravel Process Water," National Sand and Gravel
Association Circular No. 118.
20. Levine, S,, "Liquid/Solids Separation Via Wet
Classification," Rock Products, September 1972, pp.
84-95.
21. Little, A.D., "Economic Impact Analysis of New Source
Air Quality Standards on the Crushed Stone Industry,"
EPA Draft Report, 1974.
22. Llewellyn, C.M,, "The Use of Flocculants in the James
River Estuary," Miscellaneous Paper, Lone Star
Industries.
23. Llewellyn, C.M., "Maintenance of Closed Circuit Water
Systems," National Crushed Stone Association Meeting,
Charlotte, N.C., 1973.
24. Locke, S.R., Ozal, M.A., Gray, J., Jackson, R.E., and
Preis, A., "Study to Determine the Feasibility of an
Experiment to Transfer Technology to the Crushed Stone
Industry," Martin Marietta Laboratories, NSF Contract
C826, 1974,
25. Maier, F.J., "Defluoridation of Municipal Water
Supplies," Journal AWWA, August 1953, pp. 879-888.
270
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26. May, E.B., "Environmental Effects of Hydraulic Dredging
in Estuaries," Alabama Marine Resources Bulletin No, 9,
April 1973, pp. 1-85.
27. McNeal, W., and Nielsen, G., "International Directory of
Mining and Mineral Processing Operations," E/MJ,
McGraw-Hill, 1973-1974.
28. "Minerals Yearbook, Metals, Minerals, and Fuels,
Vol. 1," U.S. Department of the Interior, u * S.
Government Printing Office, Washington, D.C,, 1971,
1972.
29. "Mining Engineering, Publication of the Society of
Mining Engineers of AIME, Annual Review for 1973," Vol.
25, No. 1, January 1973; Vol. 26, No. 3, March 1974
through Vol. 26, No. 8, August 1974.
30. "Modern Mineral Processing Flowsheets," Denver Equipment
Company, 2nd Ed., Denver, Colorado
31. Monroe, R.G., "Waste water Treatment Studies in
Aggregate and Concrete Production," EPA Technology
Series EPA-R2-73-003, 1973.
32. Newport, B.D., and Moyer, J.E., "State-of-the-Art: sand
and Gravel Industry," EPA Technology Series
EPA-660/2-74-066, 1974.
33. Oleszkiewicz, J.A., and Krenkel, P.A., "Effects of sand
and Gravel Dredging in the Ohio River," Vanderbilt
University Technical Report No. 29, 1972.
34. Patton, T.C., "Silica, Macrocrystalline," Pigment
Handbook Vol.. !, J. Wiley and Sons, Inc., 1973,~pp.
157*159.
35. Popper, H., Modern Engineering cost Techniques,
McGraw-Hill, New York, 1970.
36. Price, W.L., "Dravo Dredge No. 16," National Sand and
Gravel Association Circular No. 82, 1960.
37, "Product Directory of the Refractories Industry in the
U.S.," The Refractories Institute, Pittsburgh, Pa. 1972.
38, Resource Consultants, Inc., Engineering Report, "Waste
water Treatment for Dixie Sand and Gravel Co.,"
Chattanooga, Tenn., 1972.
271
-------
39. Robertson, J.L. , "Washer/Classifier System Solves Clay
Problem at Sand and Gravel Facility," Rock Products,
March 1973, pp. 50-53.
40. Slabaugh, W.H., and Culbertsen, J.L., J. Phys. Chenu,55,
744, 1951.
41. Smith, C.A., "Pollution Control Through Waste Fines
Recovery," National Sand and Gravel Association Circular
No. 110.
42, State Directories of the Mineral Mining Industry from 36
of 50 States.
43. Trauffer, W.E., "New Vermont Talc Facility Makes
High-Grade Flotation Product for Special Uses," Pit and
Quarry.December 1964, pp. 72-74, 101.
44, Walker, S., "Production of Sand and Gravel," J. Amer.
Concrete Inst.., Vol. 26, No. 2, 1954, pp. 165-178.
45. Williams, F. J., Nezmayko, M., and Weintsitt, D.J., J.
^ Chem.., 57, 8, 1953.
272
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SECTION XIV
GLOSSARY
Aeration •* the introduction of air into the pulp in a
flotation cell in order to form air bubbles.
Aquifer - an underground stratum that yields water,
Baghouse - chamber in which exit gases are filtered through
membranes (bags) which arrest solids.
Bench - a ledge, which, in open pit mines and quarries,
forms a single, level of operation above which mineral or
waste materials are excavated from a contiguous bank or
bench face.
Berm - a horizontal shelf built for the purpose of
strengthening and increasing the stability of a slope or
to catch or arrest slope slough material; berm is
sometimes used as a synonym for bench.
Cell, cleaner - secondary cells for the retreatment of the
. concentrate from primary cells.
Cell, rougher - flotation cells in which the bulk of the
gangue is removed from the ore.
Clarifier - a centrifuge, settling tank, or other device,
for separating suspended solid matter from a liquid.
Classifier, air - an appliance for approximately sizing
crushed minerals or ores employing currents of air.
Classifier, rake - a mechanical classifier utilizing
reciprocal rakes on an inclined plane to separate coarse
from fine material contained in a water pulp.
Classifier, spiral - a classifier for separating fine-size
solids from coarser solids in a wet pulp consisting of
an interrupted-flight screw conveyor, operating in an
inclined trough.
Collector - a heteropolar compound chosen for its ability to
adsorb selectively in froth flotation and render the
adsorbing surface relatively hydrophobic.
273
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Conditioner - an apparatus in which the surfaces of the
mineral species present in a pulp are treated with
appropriate chemicals to influence their reaction during
aeration.
Crusher, cone - a machine for reducing the size of materials
by means of a truncated cone revolving on its vertical
axis within an outer chamber, the anular space between
the outer chamber and cone being tapered.
Crusher, gyratory - a primary crusher consisting of a
vertical spindle, the foot of which is mounted in an
eccentric bearing within a conical shell. The top
carries a conical crushing head revolving eccentrically.
in a conical maw.
Crusher, jaw - a primary crusher designed to reduce the size
of materials by impact or crushing between a fixed plate
and an oscillating plate or between two oscillating
plates, forming a tapered jaw.
Crusher, roll - a reduction crusher consisting of a heavy
frame on which two rolls are mounted; the rolls are
driven so that they rotate toward one another. Rock is
fed in from above and nipped between the moving rolls,
crushed, and discharged below.
Depressant - a chemical which causes substances to sink
through a froth, in froth flotation.
Dispersant - a substance (as a polyphosphate) for promoting
the formation and stabilization of a dispersion of one
substance in another.
Blunge - to mix thoroughly.
Burden - valueless material overlying the ore.
Dragline - a type of excavating equipment which employs a
rope-hung bucket to dig up and collect the material.
Dredge, bucket - a two-pontooned dredge from which are
suspended buckets which- excavate material at the bottom
of the pond and deposit it in concentrating devices on
the dredge decks.
Dredge, suction - a centrifugal pump mounted on a barge.
Drill, churn - a drilling rig utilizing a blunt-edged chisel
bit suspended from a cable for putting down vertical
holes in exploration and quarry blasting.
274
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Drill, diamond - a drilling machine with a rotating, hollow,
diamond-studded bit that cuts a circular channel around
a core which when recovered provides a columnar sample
of the rock penetrated.
Drill, rotary - various types of drill machines that rotate
a rigid, tubular string of rods to which is attached a
bit for cutting rock to produce boreholes.
Dryer, flash - an appliance in which the moist material is
fed into a column of upward-flowing hot gases with
moisture removal being virtually instantaneous.
Dryer, fluidized bed - a cool dryer which depends on a mass
of particles being fluidized by passing a stream of hot
air through it. As a result of the fluidization,
intense turbulence is created in the mass including a
rapid drying action.
Dryer, rotary - a dryer in the shape of an inclined rotating
tube used to dry loose material as it rolls through.
Electrostatic separator - a vessel fitted with positively
and negatively charged conductors used for extracting
dust from flue gas or for separating mineral dust from
gangues.
Filter, pressure - a machine utilizing pressure to increase
the removal rate of solids from tailings.
Filter, vacuum - a filter in which the air beneath the
filtering material is exhausted to hasten the process.
Flocculant - an agent that induces or promotes gathering of
suspended particles into aggregations.
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.
Frother - substances used in flotation to make air bubbles
sufficiently permanent, principally by reducing surface
tension,
Grizzly - a device for the coarse screening or scalping of
bulk materials.
HMS - Heavy Media Separation
Hydraulic Mining - mining by washing sand and dirt away with
water which leaves the desired mineral.
275
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Hydrocyclone - a cyclone separator in which a spray of water
is used.
Hydroclassifier - a machine which uses an upward current of
water to remove fine particles from coarser material.
Humphrey spiral - a concentrating device which exploits
differential densities of mixed sands by a combination
of sluicing and centrifugal action. The ore pulp
gravitates down -through a stationary spiral trough with
five turns. Heavy particles stay on the inside and the
lightest ones climb to the outside.
Jumbo - a drill carriage on which several drills are
mounted.
JTU - Jackson Turbidity Unit
Kiln, rotary - a kiln in the form of a long cylinder,
usually inclined, and slowly rotated about its axis; the
kiln is fired by a burner set axially at its lower end.
Kiln, tunnel - a long tunnel-shaped furnace through which
ware is generally moved on cars, passing progressively
through zones in which the temperature is maintained for
preheating, firing and cooling.
or
Launder - a chute or trough for conveying powdered ore,
for carrying water to or from the crushing apparatus.
Log washer - a slightly slanting trough in which revolves a
thick shaft or log, earring blades obliquely set to the
axis. Ore is fed in at the lower end, water at the
upper. The blades slowly convey the lumps of ore upward
against the current, while any adhering clay is
gradually disintegrated and floated out the lower end.
Magnetic separator - a device used to separate magnetic from
less magnetic or nonmagnetic materials.
Mill, ball - a rotating horizontal cylinder in which
non-metallic materials are ground using various types of
grinding media such as quartz pebbles, porcelain balls,
etc.
Mill, buhr - a stone disk mill, with an upper horizontal
disk rotating above a fixed lower one.
Mill, chaser - a cylindrical steel tank lined with wooden
rollers revolving 15-30 times a minute.
276
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Mill, hammer - an impact process facility consisting of a
rotor, fitted with movable hammers, that is revolved
rapidly in a vertical plane within a closely fitting
steel casing.
Mill, pebble - horizontally mounted cylindrical mill,
charged with flints or selected lumps of ore or rock.
Mill, rod - a process facility for fine grinding, somewhat
similar to a ball mill, but employing long steel rods
instead of balls to effect the grinding.
Mill, roller - a fine grinding process facility having
vertical rollers running in a circular enclosure with a
stone or iron base.
Neutralization - making neutral or inert, as by the addition
of an alkali or an acid solution.
Outcrop - the part of a rock formation that appears at the
surface of the ground or deposits that are so near to
the surface as to be found easily by digging.
Overburden - material of any nature, consolidated or
unconsolidated, that overlies a deposit of useful
materials, ores, etc.
Permeability - capacity for transmitting a fluid.
Raise - an inclined opening driven upward from a level to
connect with the level above or to explore the ground
for a limited distance above one level.
Reserve - known ore bodies that may be worked at some future
time.
Ripper -» a tractor accessory used to loosen compacted soils
and soft rocks for scraper loading.
Room and . Pillar - a system of mining in which the
distinguishing feature is the winning of 50 percent or
more of the ore in the first working. The ore is mined
in rooms separated by narrow ribs (pillars); the ore in
the pillars is won by subsequent working in which the
roof is caved in successive blocks.
Scraper - a tractor-driven surface vehicle the bottom of
which is fitted with a cutting blade which when lowered
is dragged through the'soil.
277
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Scrubber, dust - special apparatus used to remove dust from
air by washing.
Scrubber, ore - device in which coarse and sticky ore is
washed free of adherent material, or mildly
disintegrated.
Shuttle-car - a vehicle which transports raw materials from
loading machines in trackless areas of a mine to the
main transportation system.
Sink-float - processes that separate particles of different
sizes or composition on the basis of specific gravity.
Skip - a guided steel hoppit used in vertical or inclined
shafts for hoisting mineral.
Slimes - extremely fine particles derived from ore,
associated rock, clay or altered rock.
Sluice - to cause water to flow at high velocities for
wastage, for purposes of excavation, ejecting debris,
etc.
Slurry - pulp not thick enough to consolidate as a sludge
but sufficiently dewatered to flow viscously.
Stacker - a conveyor adapted to piling or stacking bulk
materials or objects.
Stope - an excavation from which ore has been excavated in a
series of steps.
Stripping ratio - the unit amount of spoil that must be
removed to gain access to a similar unit amount of ore
or mineral material.
Sump - any excavation in a mine for the collection of water
for pumping.
Table, air - a vibrating, porous table using air currents to
effect gravity concentration of sands.
Table, wet - a concentration process whereby a separation of
minerals is effected by flowing a pulp across a riffled
plane surface inclined slightly from the horizontal,
differentially shaken in the direction of the long axis
and washed with an even flow of water at right angles to
the direction of motion.
278
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Thickener - an apparatus for reducing the proportion of
water in a pulp.
TSS - total suspended solids.
Waste - the barren rock in a mine or the part of the ore
deposit that is too low in grade to be of economic value
at the time.
Weir - an obstruction placed across a stream for the purpose
of channeling the water through a notch or an opening in
the weir itself.
Wire saw ~ a saw consisting of one- and three-strand wire
cables, running over pulleys as a belt. When fed by a
slurry of sand and water and held against rock by
tension, it cuts a narrow channel by abrasion.
279
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TABLE 24
to
Multiply (English Units)
ENGLISH UNIT ABBREVIATION
METRIC UNITS
CONVERSION TABLE
by To obtain (Metric units)
CONVERSION ABBREVIATION METRIC UNIT
acre
acre - Feet
British Thermal Unit
British Thermal Unit/
pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gallon
gallon/minute
horsepower
Inches
Inches of mercury
pounds
million gallons/day
mile
pound/square Inch
(gauge)
square feet
square Inches
tons (short)
yard
ac
ac ft
BTU
BTU/lb
cfm
cfs
cu ft
cu ft
cu in
Fo
ft
gal
gpm
hp
in
in Hg
Eb
mgd
mi
pslg
sq ft
sq in
t
y
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555 (°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig+1)*
0.0929
6.452
0.907
0.9144
ha
cu m
kg cal
kg cal/kg
cu m/min
cu m/min
cu m
1
cu cm
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/ minute
cubic meters
liters
cubic centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric tons (1000 kilograms)
meters
* Actual conversion/ not a multiplier
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POSTAGE AND FEES PAID
U.S. ENVIRONMENTAL PROTECTION AGENCY (A-107) ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460 EPA-335
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