United States Effluent Guidelines Division EPA-440/1-84/019-b3
Environmental Protection WH-552 July 1984
Agency Washington, D.C. 20460
Water and Waste Management
Development Proposed
Document for
Effluent Limitations
Guidelines and
Standards for the
Nonferrous Metals
Point Source Category
Phase II
Supplemental Development
Document For:
Primary Precious Metals and Mercury
-------
DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES AND STANDARDS
for the
NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY
PHASE II
Primary Precious Metals and Mercury Supplement
Jack E. Ravan
Assistant Administrator for Water
Edwin L. Johnson
Director
Office of Water Regulations and Standards
protcction
;^' Srreet
60604
Jeffery D. Denit, Director
Effluent Guidelines Division
Ernst P. Hall, P.E., Chief
Metals and Machinery Branch
James R. Berlow, P.E.
Technical Project Officer
July 1984
U.S. Environmental Protection Agency
Office of Water
Office of Water Regulations and Standards
Effluent Guidelines Division
Washington, D.C. 20460
-------
U,S- EnviKjreftsnto! Prot3o:!cn Agency
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
TABLE OF CONTENTS
Section Page
I SUMMARY AND CONCLUSIONS 1
II RECOMMENDATIONS 5
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 5
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 11
NSPS FOR THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY 15
PSNS FOR THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY 20
III INDUSTRY PROFILE 25
DESCRIPTION OF PRIMARY PRECIOUS METALS
PRODUCTION 25
RAW MATERIALS 25
SMELTING - 25
GOLD-SILVER SEPARATION 26
FURTHER PURIFICATION 26
PROCESS WASTEWATER SOURCES 27
DESCRIPTION OF PRIMARY MERCURY PRODUCTION. ... 27
RAW MATERIALS 27
ROASTING 27
PROCESS WASTEWATER SOURCES 28
OTHER WASTEWATER SOURCES 28
AGE, PRODUCTION, AND PROCESS PROFILE 28
IV SUBCATEGORIZATION 37
FACTORS CONSIDERED IN SUBCATEGORIZATION 37
FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY 38
OTHER FACTORS 39
PRODUCTION NORMALIZING PARAMETERS 39
V WATER USE AND WASTEWATER CHARACTERISTICS .... 41 .
WASTEWATER FLOW RATES 42
WASTEWATER CHARACTERISTICS DATA 43
DATA COLLECTION PORTFOLIOS 43
FIELD SAMPLING DATA 44
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
TABLE OF CONTENTS (Continued)
Section
VI
VII
VIII
WASTEWATER CHARACTERISTICS AND FLOWS BY
SUBDIVISION 45
SMELTER WET AIR POLLUTION CONTROL 45
SILVER CHLORIDE REDUCTION SPENT SOLUTION .... 46
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL . . 46
ELECTROLYTE PREPARATION WET AIR POLLUTION
CONTROL 46
SILVER CRYSTAL WASH WATER 46
GOLD SLIMES ACID WASH AND WATER RINSE 47
CALCINER WET AIR POLLUTION CONTROL 47
CALCINE QUENCH WATER 47
CALCINER STACK GAS CONTACT COOLING WATER .... 47
CONDENSER SLOWDOWN 48
MERCURY CLEANING BATH WATER 48
SELECTION OF POLLUTANT PARAMETERS 77
CONVENTIONAL POLLUTANT PARAMETERS 77
TOXIC POLLUTANTS 78
TOXIC POLLUTANTS NEVER DETECTED 78
TOXIC POLLUTANTS NEVER FOUND ABOVE THEIR
ANALYTICAL QUANTIFICATION CONCENTRATION 81
TOXIC POLLUTANTS PRESENT BELOW CONCENTRATIONS
ACHIEVABLE BY TREATMENT 81
TOXIC POLLUTANTS DETECTED IN A SMALL NUMBER
OF SOURCES 82
TOXIC POLLUTANTS SELECTED FOR FURTHER
CONSIDERATION IN ESTABLISHING LIMITATIONS
AND STANDARDS 83
CONTROL AND TREATMENT TECHNOLOGIES 89
CURRENT CONTROL AND TREATMENT PRACTICES 89
CONTROL AND TREATMENT OPTIONS 90
OPTION A 90
OPTION B 90
OPTION C 90
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS. . . 93
TREATMENT OPTIONS FOR EXISTING SOURCES 93
OPTION A 93
OPTION B 93
OPTION C 93
LL
-------
Section
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
TABLE OF CONTENTS (Continued)
COST METHODOLOGY 94
NONWATER QUALITY ASPECTS 94
ENERGY REQUIREMENTS 94
SOLID WASTE 94
AIR POLLUTION 94
IX BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
AVAILABLE 99
TECHNICAL APPROACH TO BPT 99
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES. . 101
BPT OPTION SELECTION 102
WASTEWATER DISCHARGE RATES 102
SMELTER WET AIR POLLUTION CONTROL 102
SILVER CHLORIDE REDUCTION SPENT SOLUTION .... 103
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL . . 103
ELECTROLYTE PREPARATION WET AIR POLLUTION
CONTROL 103
SILVER CRYSTAL WASH WATER 103
GOLD SLIMES ACID WASH AND WATER RINSE 103
CALCINER WET AIR POLLUTION CONTROL 104
CALCINE QUENCH WATER 104
CALCINER STACK GAS CONTACT COOLING WATER .... 104
CONDENSER SLOWDOWN 104
MERCURY CLEANING BATH WATER 104
REGULATED POLLUTANT PARAMETERS 104
EFFLUENT LIMITATIONS 105
X BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE 115
TECHNICAL APPROACH TO BAT 115
OPTION A 116
OPTION B 116
Recycle of Water Used in Wet Air Pollution
Control 117
OPTION C 118
INDUSTRY COST AND ENVIRONMENTAL BENEFITS .... 118
POLLUTANT REMOVAL ESTIMATES 118
COMPLIANCE COSTS 119
BAT OPTION SELECTION 119
ill
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
TABLE OF CONTENTS (Continued)
Section
XI
XII
WASTEWATER DISCHARGE RATES 120
SMELTER WET AIR POLLUTION CONTROL 120
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL . . 120
CALCINER WET AIR POLLUTION CONTROL 121
REGULATED POLLUTANT PARAMETERS 121
EFFLUENT LIMITATIONS 122
NEW SOURCE PERFORMANCE STANDARDS 135
TECHNICAL APPROACH TO NSPS 135
OPTION A 135
OPTION B 136
OPTION C 136
NSPS OPTION SELECTION 136
REGULATED POLLUTANT PARAMETERS 136
NEW SOURCE PERFORMANCE STANDARDS 136
PRETREATMENT STANDARDS 145
TECHNICAL APPROACH TO PRETREATMENT 145
PRETREATMENT STANDARDS FOR NEW SOURCES 146
OPTION A 146
OPTION B 146
OPTION C 147
PSNS OPTION SELECTION 147
REGULATED POLLUTANT PARAMETERS 147
PRETREATMENT STANDARDS 147
XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
153
IV
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
LIST OF TABLES
Number Page
III-1
III-2
III-3
III-4
III-5
V-1
V-2
V-3
V-4
V-5
V-6
V-7
V-8
V-9
INITIAL OPERATION YEAR (RANGE) SUMMARY OF
PLANTS IN THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY BY DISCHARGE TYPE
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
SUMMARY OF PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY PROCESSES AND ASSOCIATED
WASTE STREAMS
WATER USE AND DISCHARGE RATES FOR
SMELTER WET AIR POLLUTION CONTROL. .......
WATER USE AND DISCHARGE RATES FOR
SILVER CHLORIDE REDUCTION SPENT SOLUTION ....
WATER USE AND DISCHARGE RATES FOR ELECTROLYTIC
CELLS WET AIR POLLUTION CONTROL
WATER USE AND DISCHARGE RATES FOR ELECTROLYTE
PREPARATION WET AIR POLLUTION CONTROL
WATER USE AND DISCHARGE RATES FOR
SILVER CRYSTAL WASH WATER
WATER USE AND DISCHARGE RATES FOR
GOLD SLIMES ACID WASH AND WATER RINSE ;
WATER USE AND DISCHARGE RATES FOR
CALCINER WET AIR POLLUTION CONTROL
WATER USE AND DISCHARGE RATES FOR
CALCINE QUENCH WATER
WATER USE AND DISCHARGE RATES FOR
CALCINER STACK GAS CONTACT COOLING WATER ....
29
30
31
32
33
49
50
51
52
53
54
55
56
57
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
LIST OF TABLES (Continued)
Number Page
V-10 WATER USE AND DISCHARGE RATES FOR
CONDENSER SLOWDOWN 58
V-11 WATER USE AND DISCHARGE RATES FOR
MERCURY CLEANING BATH-WATER 59
V-12 PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SAMPLING DATA CALCINER WET AIR POLLUTION CONTROL
RAW WASTEWATER 60
V-13 PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SAMPLING DATA CALCINE QUENCH WATER
RAW WASTEWATER 66
V-14 PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SAMPLING DATA CALCINER STACK GAS CONTACT
COOLING DATA RAW WASTEWATER 69
V-15 PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SAMPLING DATA MERCURY CLEANING BATH WATER
RAW WASTEWATER 72
VI-1 FREQUENCY OF OCCURRENCE OF TOXIC POLLUTANTS
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
RAW WASTEWATER 85
VI1-1 SUMMARY OF WASTE STREAMS AND TREATMENT
PRACTICES IN PRIMARY PRECIOUS METALS AND
MERCURY PLANTS 91
VIII-1 COST OF COMPLIANCE FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY DIRECT
DISCHARGERS 97
IX-1 BPT WASTEWATER DISCHARGE RATES FOR THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY 106
IX-2 BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 107
X-1 CURRENT RECYCLE PRACTICES WITHIN THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY 123
vi
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
LIST OF TABLES (Continued)
Number Page
X-2 POLLUTANT REMOVAL ESTIMATES FOR DIRECT
DISCHARGERS IN THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY 124
X-3 COST OF COMPLIANCE FOR DIRECT DISCHARGERS IN
THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY 125
X-4 BAT WASTEWATER DISCHARGE RATES FOR THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY 126
X-5 BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 127
XI-1 NSPS WASTEWATER DISCHARGE RATES FOR THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY. 137
XI-2 NSPS FOR THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY 138
XII-1 PSNS WASTEWATER DISCHARGE RATES FOR THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY 148
XI1-2 PSNS FOR THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY 149
vii
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
LIST OF FIGURES
Number Page
II1-1 PRIMARY PRECIOUS METALS PRODUCTION PROCESSES . . 34
III-2 PRIMARY MERCURY PRODUCTION PROCESSES 35
III-3 GEOGRAPHIC LOCATIONS OF THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY PLANTS 36
V-1 SAMPLE LOCATIONS AT PRIMARY PRECIOUS METALS
AND MERCURY PLANT A 75
IX-1 BPT TREATMENT SCHEME FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 113
X-1 BAT TREATMENT SCHEME FOR OPTION A 131
X-2 BAT TREATMENT SCHEME FOR OPTION B 132
X-3 BAT TREATMENT SCHEME FOR OPTION C 133
IX
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION I
SUMMARY AND CONCLUSIONS
Pursuant to Sections 301, 304, 306, 307, and 501 of the Clean
Water Act and the provisions of the Settlement Agreement in
Natural Resources Defense Council v. Train, 8 ERG 2120 (D.D.C.
1976) modified. 12 ERG 1833 (D.D.C. 1979), EPA has collected and
analyzed data for plants in the primary precious metals and mer-
cury subcategory. EPA has never proposed or promulgated effluent
limitations or standards for this subcategory. This document and
the administrative record provide the technical basis for propos-
ing effluent limitations based on best practicable technology
(BPT) and best available technology (BAT) for existing direct
dischargers, pretreatment standards for new indirect dischargers
(PSNS), and standards of performance for new source direct
dischargers (NSPS).
The primary precious metals and mercury subcategory is comprised
of eight plants. Of the eight plants, one discharges directly to
rivers, lakes, or streams; none discharge to publicly owned
treatment works (POTW); and seven achieve zero discharge of
process wastewater.
EPA first studied the primary precious metals and mercury sub-
category to determine whether differences in raw materials, final
products, manufacturing processes, equipment, age and size of
plants, and water usage, required the development of separate
effluent limitations and standards for different segments of the
subcategory. This involved a detailed analysis of wastewater
discharge and treated effluent characteristics, including (1) the
sources and volume of water used, the processes used, and the
sources of pollutants and wastewaters in the plant; and (2) the
constituents of wastewaters, including toxic pollutants. As a
result, 11 subdivisions have been identified for this subcategory
that warrant separate effluent limitations. These include:
Smelter wet air pollution control,
Silver chloride reduction spent solution,
Electrolytic cells wet air pollution control,
Electrolyte preparation wet air pollution control,
Silver crystal wash water,
Gold slimes acid wash and water rinse,
Calciner wet air pollution control,
Calcine quench water,
Calciner stack gas contact cooling water,
Condenser blowdown, and
Mercury cleaning bath water.
-------
EPA also identified several distinct control and treatment
technologies (both in-plant and end-of-pipe) applicable to the
primary precious metals and mercury subcategory. The Agency
analyzed both historical and newly generated data on the
performance of these technologies, including their nonwater
quality environmental impacts and air quality, solid waste
feneration, and energy requirements. EPA also studied various
low reduction techniques reported in the data collection
portfolios (dcp) and plant visits.
Engineering costs were prepared for each of the control and
treatment options considered for the subcategory. These costs
were then used by the Agency to estimate the impact of imple-
menting the various options on the subcategory. For each control
and treatment option that the Agency found to be most effective
and technically feasible in controlling the discharge of pollu-
tants, we estimated the number of potential closures, number of
employees affected, and impact on price. These results are
reported in a separate document entitled "The Economic Impact
Analysis of Proposed Effluent Limitations Guidelines and
Standards for the Nonferrous Smelting and Refining Industry."
After examining the various treatment technologies, the Agency
has identified BPT to represent the average of the best existing
technology in the nonferrous metals manufacturing industry.
Metals removal based on chemical precipitation and sedimentation
technology is the basis for the BPT limitations. Oil skimming
was selected as the technology basis for oil and grease limita-
tions. To meet the BPT effluent limitations based on this
technology, the primary precious metals and mercury subcategory
is expected to incur a capital cost of $27,500 and an annual cost
of $9,000.
For BAT, the Agency has built upon the BPT technology basis by
adding, in-process control technologies which include recycle of
process water from air pollution control waste streams. Filtra-
tion is added as an effluent polishing step to the end-of-pipe
treatment scheme. To meet the BAT effluent limitations based on
this technology, the primary precious metals and mercury subcate-
gory is estimated to incur a capital cost of $30,000 and an
annual cost of $10,000.
NSPS are equivalent to BAT. In selecting NSPS, EPA recognizes
that new plants have the opportunity to implement the best and
most efficient manufacturing processes and treatment technology.
As such, the technology basis of BAT has been determined as the
best demonstrated technology.
-------
EPA is not proposing PSES for the primary precious metals and
mercury subcategory because there are no indirect dischargers.
For PSNS, the Agency selected end-of-pipe treatment and
in-process flow reduction control techniques equivalent to NSPS,
The best conventional technology (BCT) replaces BAT for the
control of conventional pollutants. BCT is not being proposed
because the methodology for BCT has not yet been finalized.
The mass limitations and standards for BPT, BAT, NSPS, and PSNS
are presented in Section II.
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION II
RECOMMENDATIONS
1. EPA has divided the primary precious metals and
mercury subcategory into 11 subdivisions for the
purpose of effluent limitations and standards.
These subdivisions are:
(a) Smelter wet air pollution control,
(b) Silver chloride reduction spent solution,
(c) Electrolytic cells wet air pollution control,
(d) Electrolyte preparation wet air pollution
control,
(e) Silver crystal wash water,
(f) Gold slimes acid wash and water rinse,
(g) Calciner wet air pollution control,
(h) Calcine quench water,
(i) Calciner stack gas contact cooling water,
(j) Condenser blowdown, and
(k) Mercury cleaning bath water.
2. BPT is proposed based on the performance achievable
by the application of chemical precipitation and
sedimentation (lime and settle) technology, along
with preliminary treatment consisting of oil skim-
ming for selected waste streams. The following BPT
effluent limitations are proposed:
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 27.590 12.280
Lead 5.544 2.640
Mercury 3.300 1.320
Silver 5.412 2.244
Zinc 19.270 8.052
Oil and grease 264.000 158.400
Total suspended 541.200 257.400
solids
pH Within the range of 7.5 to 10.0
at all times
-------
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property _ Any One Day _ Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
solids
PH
of silver reduced
0.836
0.168
0.100
0.164
0.584
8.000
16.400
Within the rang
in solution
0.372
0.080
0.040
0.068
0.244
4.800
7.800
je of 7.5 to 1 0. 0
at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 413.800 184.100
Lead 83.160 39.600
Mercury 49.500 19.800
Silver 81.180 33.660
Zinc 289.100 120.800
Oil and grease 3,960.000 2,376.000
Total suspended 8,118.000 3,861.000
solids
pH Within the range of 7.5 to 10.0
at all times
-------
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
i
Pollutant or Maximum for- Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.105 0.047
Lead 0.021 0.010
Mercury 0.013 0.005
Silver 0.021 0.009
Zinc 0.073 0.031
Oil and grease 1.000 0.600
Total suspended 2.050 0.975
solids
pH Within the range of 7.5 to 10.0
at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.606 0.270
Lead 0.122 0.058
Mercury 0.073 0.029
Silver 0.119 0.049
Zinc 0.423 0.177
Oil and grease 5.800 3.480
Total suspended 11.890 5.655
solids
pH Within the range of 7.5 to 10.0
at all times
-------
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
ing/troy ounce of gold slimes washed
Arsenic 8.360 3.720
Lead 1.680 0.800
Mercury 1.000 0.400
Silver 1.640. 0.680
Zinc 5.840 2.440
Oil and grease 80.000 48.000
Total suspended 164.000 78.000
solids
pH Within the range of 7.5 to 10.0
at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rag/kg (Ib/million Ibs) of mercury condensed
Arsenic 388.800 173.000
Lead 78.120 37.200
Mercury 46.500 18.600
Silver 76.260 31.620
Zinc 271.600 113.500
Oil and grease 3,720.000 2,232.000
Total suspended 7,626.000 3,627.000
solids
pH Within the range of 7.5 to 10.0
at all times
8
-------
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 36.790 16.370
Lead 7.392 3.520
Mercury 4.400 1.760
Silver 7.216 2.992
Zinc 25.700 10.740
Oil and grease 352.000 • 211.200
Total suspended 721.600 343.200
solids
pH Within the range of 7.5 to 1 0. 0
at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/miliion Ibs) of mercury condensed
Arsenic 8.674 3.860
Lead 1.743 0.830
Mercury 1.038 0.415
Silver 1.702 0.706
Zinc 6.059 2.532
Oil and grease 83.000 49.800
Total suspended 170.200 80.930
solids
pH Within the range of 7.5 to 10.0
at all times
-------
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 28.840 12.830
Lead 5.796 2.760
Mercury 3.450 1.380
Silver 5.658 2.346
Zinc 20.150 . 8.418
Oil and grease 276.000 165.600
Total suspended 565.800 269.100
solids
pH Within the range of 7.5 to 10.0
at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 2.926 1.302
Lead 0.588 0.280
Mercury 0.350 0.140
Silver 0.574 0.238
Zinc 2.044 0.854
Oil and grease 28.000 16.800
Total suspended 57.400 27.300
solids
pH Within the range of 7.5 to 10.0
at all times
BAT is proposed based on the performance achievable
by the application of chemical precipitation, sedi-
mentation, and multimedia filtration (lime, settle,
and filter) technology and in-process flow reduc-
tion methods, along with preliminary treatment con-
sisting of oil skimming for selected waste streams.
The following BAT effluent limitations are
proposed:
10
-------
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 1.807 0.806
Lead 0.364 0.169
Mercury 0.195 0.078
Silver 0.377 0.156
Zinc 1.326 0.546
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver reduced in solution
Arsenic 0.556 0.248
Lead 0.112 0.052
Mercury 0.060 0.024
Silver 0.116 0.048
Zinc 0.408 0.168
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 12.280
Lead 5.544 2.574
Mercury 2.970 1.188
Silver 5.742 2.376
Zinc 20.200 8.316
11
-------
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver
0.
0.
0.
0.
0.
in electrolyte
070
014
008
015
051
produced
0.031
0.007
0.003
0.006
0.021
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver crystals
0.403
0.081
0.044
0.084
0.296
washed
0.180
0.038
0.017
0.035
0.122
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant PropertyAny One DayMonthly Average
Arsenic
Lead
Mercury
Silver
Zinc
mg/troy ounce of gold
5.560
1.120
0.600
1.160
4.080
slimes washed
2.480
0.520
0.240
0.480
1.680
12
-------
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million
Ibs) of mercury
30.580
6.160
3.300
6.380 .
22.440
condensed
13.640
2.860
1.320
2.640
9.240
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 2.112
Zinc 17.950 7.392
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 5.769 2.573
Lead 1.162 0.540
Mercury 0.623 0.249
Silver 1.204 0.498
Zinc 4.233 1.743
13
-------
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 19.180 8.556
Lead 3.864 1.794
Mercury 2.070 0.828
Silver 4.002 1.656
Zinc 14.080 5.796
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 0.168
Zinc 1.428 0.588
4. NSPS are proposed based on the performance achiev-
able by the application of chemical precipitation,
sedimentation, and multimedia filtration (lime,
settle, and filter) technology, and in-process flow
reduction control methods, along with preliminary
treatment consisting of oil skimming for selected
waste streams. The following effluent standards
are proposed for new sources:
14
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 1.807 0.806
Lead 0.364 0.169
Mercury 0.195 0.078
Silver 0.377 0.156
Zinc 1.326 0.546
Oil and grease 13.000 13.000
Total suspended 19.500 15.600
solids
pH Within the range of 7.5 to 10.0
at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver reduced in solution
Arsenic 0.556 0.248
Lead 0.112 0.052
Mercury 0.060 0.024
Silver 0.116 0.048
Zinc 0.408 0.168
Oil and grease 4.000 4.000
Total suspended 6.000 4.800
solids
pH Within the range of 7.5 to 10.0
at all times
15
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 12.280
Lead 5.544 2.574
Mercury 2.970 1.188
Silver 5.742 .2.376
Zinc 20.200 8.316
Oil and grease 198.000 198.000
Total suspended 297.000 237.600
solids
pH Within the range of 7.5 to 10.0
at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.070 0.031
Lead 0.014 0.007
Mercury 0.008 0.003
Silver 0.015 0.006
Zinc 0.051 0.021
Oil and grease 0.500 0.500
Total suspended 0.750 0.600
solids
pH Within the range of 7.5 to 10.0
at all times
16
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.403 0.180
Lead 0.081 0.038
Mercury 0.044 0.017
Silver 0.084, 0.035
Zinc 0.296 0.122
Oil and grease 2.900 2.900
Total suspended 4.350 3.480
solids
pH Within the range of 7.5 to 10.0
at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold slimes washed
Arsenic 5.560 2.480
Lead 1.120 0.520
Mercury 0.600 0.240
Silver 1.160 0.480
Zinc 4.080 1.680
Oil and grease 40.000 40.000
Total suspended 60.000 48.000
solids
pH Within the range of 7.5 to 10.0
at all times
17
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 30.580 13.640
Lead 6.160 2.860
Mercury 3.300 1.320
Silver 6.380 2.640
Zinc 22.440 9.240
Oil and grease 220.000 220.000
Total suspended 330.000 264.000
solids
pH Within the range of 7.5 to 10.0
at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rag/kg (Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 2.112
Zinc 17.950 7.392
Oil and grease 176.000 176.000
Total suspended 264.000 211.200
solids
pH Within the range of 7.5 to 10.0
at all times
18
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
nig/kg (Ib/million Ibs) of mercury condensed
Arsenic 5.769 2.573
Lead 1.162 0.540
Mercury 0.623 0.249
Silver 1.204 0.498
Zinc 4.233 1.743
Oil and grease 41.500 41.500
Total suspended 62.250 49.800
solids
pH Within the range of 7.5 to 10.0
at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(j) Condenser Blowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 19.180 8.556
Lead 3.864 1.794
Mercury 2.070 0.828
Silver 4.002 1.656
Zinc 14.080 5.796
Oil and grease 138.000 138.000
Total suspended 207.000 165.600
solids
pH Within the range of 7. 5 to 10.0
at all times
19
-------
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 0.168
Zinc 1.428 0.588
Oil and grease 14.000 14.000
Total suspended 21.000 16.800
solids
pH Within the range of 7.5 to 10.0
at all times
5. EPA is not proposing PSES for the primary precious
metals and mercury subcategory because there are no
indirect dischargers.
6. PSNS are proposed based on the performance achiev-
able by the application of chemical precipitation,
sedimentation, and multimedia filtration (lime,
settle, and filter) technology, and in-process flow
reduction control methods, along with preliminary
treatment consisting of oil skimming for selected
waste streams. The following pretreatment
standards are proposed for new sources:
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 1.807 0.806
Lead 0.364 0.169
Mercury 0.195 0.078
Silver 0.377 0.156
Zinc 1.326 0.546
20
-------
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver reduced in solution
Arsenic 0.556 0.248
Lead 0.112 0.052
Mercury 0.060 0.024
Silver 0.116 0.048
Zinc 0.408 0.168
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 12.280
Lead 5.544 2.574
Mercury 2.970 . 1.188
Silver 5.742 2.376
Zinc 20.200 8.316
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.070 0.031
Lead 0.014 0.007
Mercury 0.008 0.003
Silver 0.015 0.006
Zinc 0.051 0.021
21
-------
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.403 0.180
Lead 0.081 0.038
Mercury 0.044 0.017
Silver 0.084 0.035
Zinc 0.296 0.122
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold slimes washed
Arsenic 5.560 2.480
Lead 1.120 0.520
Mercury 0.600 0.240
Silver 1.160 0.480
Zinc 4.080 1.680
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 30.580 13.640
Lead 6.160 2.860
Mercury 3.300 1.320
Silver 6.380 2.640
Zinc 22.440 9.240
22
-------
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUB CATEGORY
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
ing/kg (Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 2.112
Zinc 17.950 7.392
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million
Ibs) of mercury
5.769
1.162
0.623
1.204
4.233
condensed
2.573
0.540
0.249
0.498
1.743
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million
Ibs) of mercury
19.180
3. -864
2. U/0
4.002
14.080
condensed
8.556
1.794
0.828
1.656
5.796
23
-------
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 , 0.168
Zinc 1.428 0.588
7. EPA is not proposing BCT for the primary precious
metals and mercury subcategory at this time.
24
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION III
INDUSTRY PROFILE
This section of the primary precious metals and mercury supple-
ment describes the raw materials and processes used in producing
primary precious metals and mercury and presents a profile of the
primary precious metals and mercury plants identified in this
study. For a discussion of the purpose, authority, and methodol-
ogy for this study, and a general description of the nonferrous
metals manufacturing category, refer to Section III of the
General Development Document.
DESCRIPTION OF PRIMARY PRECIOUS METALS PRODUCTION
The production of primary precious metals can be divided into
three distinct stages - smelting to produce Dore metal, separa-
tion of gold and silver, and gold and silver purification. The
processes used in each stage vary with the type and purity of raw
material used. The primary precious metals production process is
presented schematically in Figure III-1 and described below.
RAW MATERIALS
Primary precious metals are produced from gold and silver bearing
concentrates produced from precious metal ores and as a by-prod-
uct from the beneficiation of base metal ores. A small amount is
also produced from placer mining operations. Precious metal ores
are mined at various locations in the western United States.
Mining and beneficiation processes for precious metal-bearing
ores, including cyanidation, amalgamation, flotation, and
gravity concentration are outside the scope of this subcategory.
Both the mining and beneficiation operations are regulated as
part of the Ore Mining and Dressing Point Source Category.
Primary precious metals produced as a by-product of primary
copper refining operations are regulated under nonferrous metals
manufacturing phase I as part of the primary copper refining
subcategory.
SMELTING
The gold and silver manufacturing process begins when the
precious metals bearing concentrate is sent through a Dore fur-
nace (smelter). In the Dore furnace, the gold, silver, and other
precious metals are smelted in the presence of a fluxing agent
25
-------
(commonly soda ash, borax, or silica). This smelting operation
produces a slag containing impurities such as copper and zinc,
and a gold base alloy known as Dore, which may also contain
silver.
The Dore gold may be cast and sold as a product or further
refined.
GOLD-SILVER SEPARATION
The separation of gold and silver from Dore bars is accomplished
through electrolytic refining or by the Miller process. In the
electrolytic method, the Dore metal is cast into anodes and
placed into a solution of silver nitrate (AgNO^) electrolyte.
When a current is applied fine silver is deposited upon the
cathode. This silver is removed, washed, and cast into bars of
fine silver for sale. Gold remains as slimes in the canvas anode
bags. Gold slimes are washed with acid and rinsed with water
before being cast as a product. This gold is about 99 percent
pure. Silver is recovered in a cementation step from the silver
crystals wash water and from the gold slimes acid wash and rinse
water. In the cementation process, copper is added to the solu-
tion and replaces the silver, causing the silver to precipitate
out of the solution. The recovered silver is returned to the
anode casting stage.
Gold and silver can also be separated from the Dore metal while
it is still molten. This purification step is known as the
Miller process and consists of bubbling chlorine gas through the
molten Dore metal in a parting furnace. This process converts
the silver into silver chloride salt and volatilizes base metal
impurities. The silver chloride salt rises to the surface and is
skimmed off for further processing. The gold produced by the
Miller process can be further purified by electrolytic refining
or immediately cast as a product. The silver chloride salt which
is skimmed off is remelted and cast into slabs. These slabs are
reduced to silver metal in an acid solution. The resulting
silver metal is remelted in the presence of borax flux and molten
silver is then cast as a product.
FURTHER PURIFICATION
After separation, gold and silver can be further refined by vari-
ous means. One technique to further refine gold is electrolysis.
Impure gold is cast into anodes and purified electrolytically by
the Wholwill process in a chloride solution. Gold, which is
oxidized at the anode, passes into solution and is deposited upon
the cathode. The gold cathode is melted and cast into bars with
a purity greater than 99.9 percent. As described above, gold
slimes can be further purified using an acid wash and water rinse
process.
26
-------
PROCESS WASTEWATER SOURCES
Although a variety of processes are involved in primary precious
metals production, the process wastewater sources can be sub-
divided as follows:
1. Smelter wet air pollution control,
2. Silver chloride reduction spent solution,
3. Electrolytic cells wet air pollution control,
4. Electrolyte preparation wet air pollution control,
5. Silver crystal wash water, and
6. Gold slimes acid wash and water rinse.
DESCRIPTION OF PRIMARY MERCURY PRODUCTION
Primary mercury is produced from mercury ores and gold-bearing
ores by roasting or calcining. The primary mercury production
process is presented schematically in Figure III-2 and described
below.
RAW MATERIALS
The principal source of mercury is cinnabar ore (mercury sul-
fide). Cinnabar ore is mined primarily in Nevada, California,
and Oregon. In addition, a small amount of mercury is recovered
as a co-product from gold ore.
ROASTING
After mining and beneficiation, mercury is extracted from
mercury-bearing ores by roasting or calcining. In the roasting
process, the mercury is vaporized and then recovered in a con-
denser, while the sulfur is oxidized to SOo. Some water may
condense with the mercury and is discharged as a waste stream.
The mercury recovered from the condenser may be washed with water
prior to being sold. The mining and beneficiation stage of
mercury production is not within the scope of this subcategory.
Sulfur dioxide (S02> and other gaseous emissions from the mer-
cury roasting furnace are controlled with a multistage scrubber.
Sulfur dioxide emissions are controlled with a wet scrubber.
After S02 removal, the clean stack gases are cooled with
contact cooling water and discharged to the atmosphere. Calciner
S02 scrubber liquor and stack gas contact cooling water are
discharged as waste streams.
27
-------
PROCESS WASTEWATER SOURCES
Although a variety of processes are involved in primary mercury
production, the process wastewater sources can be subdivided as
follows:
1. Calciner wet air pollution control,
2. Calcine quench water,
3. Calciner stack gas contact cooling water,
4. Condenser blowdown, and
5. Mercury cleaning bath water.
OTHER WASTEWATER SOURCES
There are other waste streams associated with the primary
precious metals and mercury subcategory. These waste streams
include, but are not limited to:
1. Casting contact cooling water,
2. Stormwater runoff, and
3. Maintenance and cleanup water.
These waste streams are not considered as a part of this rulemak-
ing. EPA believes that the flows and pollutant loadings associ-
ated with these waste streams are insignificant relative to the
waste streams selected, or are best handled by the appropriate
permit authority on a case-by-case basis under authority of
Section 403 of the Clean Water Act.
AGE, PRODUCTION, AND PROCESS PROFILE
Figure III-3 shows the location of the eight primary precious
metals and mercury plants operating in the United States. Four
of the eight plants are located in Nevada, with one of the
remaining plants each being located in Idaho, Montana, Colorado,
and South Dakota.
Table III-1 shows the relative age and discharge status of the
primary precious metals and mercury plants. Seven of the eight
plants in this subcategory have a zero discharge status, and one
plant is a direct discharge facility. The average plant age is
less than 12 years. Tables III-2 to III-4 provide a summary of
the current production ranges. It can be seen that production of
gold is evenly spread along the ranges with a mean production of
70,000 troy ounces/year. The mean production of silver is
222,500 troy ounces/year.
Table III-5 provides a summary of the number of plants generating
wastewater for the waste streams associated with various proces-
ses and the number of plants with the process.
28
-------
Table III-1
INITIAL OPERATING YEAR (RANGE) SUMMARY OF PLANTS IN THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY BY DISCHARGE TYPE
Initial Operating Year (Range)
(Plant Age in Years)
Type of
Plant
Direct
Indirect
Zero
TOTAL
1983-
1973
(0-11)
1
0
4
5
1972-
1968
(12-16)
0
0
1
1
1967-
1958
(17-26)
0
0
1
1
1957-
1918
(27-66)
0
0
0
0
Before
1918
(66%)
0
0
1
1
Total
1
0
]_
8
29
-------
CM
1
I— 1
l-t
W
OJ
r-t
,0
CO
H
CO
i-jj
H
§
CO
o
o
1— 1
o
w
OS ><
OH OS
o
>< o
OS W
3§
0 O
> (-1
in 4J
r>. >— x
O O CM
O/^N
0 W
0 !>•
in •
r*» N
1 O
,— ,
0 >
0 O
- 1-1
O 4J
O O •
1 O
O >-(
4->
C
CO
r-l
PH
UH
O
-
H
T- O *-
4J
o
4J (1)
O J-i
CU 1-1 O
>-l T3 M
•^ c
-------
V-4 CO
rH V 4J
CO 4314-1 C
4-1 0 O CO
OS rH
H Z 0<
ml v£>
CO
1
1— 1
l-l
M
H
&< 03
*8
(^ W
2i H
*S "43
M CJ
&5 eq
CM 3
CO
u
s >•
p 05
3
as u
O «
fa U
s
CO
W Q
o z
S3 ^3
«
3
O
^^
EH
U
3
Q
0
OS
OH
CN
00
<3\
r—
U
O
14-1
(U
OC
c
CO
a;
c
o
•H
4J
CJ
d
T3
0
Vj
(^
M
(U
^-1
••J
•M
CO
^v
l-(
>
o^*
0 •
0 N
« O
o
0 IX
m o
s\ n
4-)
•^s
o
O/-N
0 U
- >-
0^
o •
m N
I O
r—
0 >>
o o
- i-4
0 4J
m ^-^
O-^N
0 H
0 >
o •
m N
1 O
0 £*
o o
•* tl
M
O 4J
T—
s~\
>-l
>-
o *-*
o •
O N
- 0
o
1^^
*•" p^
1 O
o n
4-1
^^
O r-
r- O
o i-
4-1
(U CO
(XrH
4-1
O
o
-------
Table III-4
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY
Mercury production ranges are not presented here because the
information on which they are based has been claimed
confidential.
32
-------
cu C
e cu
CO 00 O 4-)
4-> c 1-1 to
4J 3:
CO 4J
E r-l rJ
3 CM O
co cu
4J
cu w
2 CUC
(4-4 CU CU !S
O P^ C5
4J
M CO
o cu
O 'rl J-l
-2 CO 4J
J-l CO CO
o» co
CO
co
O
P6
air pollution control
4->
CU
J5
J-i
CU
4-1
r-l
cu
E
CO
X"N
•
52
•
PM
^-s
air pollution control
^j
cu
[5
(-1
j3
•H
CJ
r-l
CO
O
x^
00
33
•^s
ch
ck gas cooling water
owdown
C COr-4
CU 4-lrO
d co
C71 J-l
J-l CU
i-l CU
O OTJ
rM r-l C
CO CO O
0 00
X-NX-\X-N
00 0000
cSSS
c
0
•H
4J
cO
^t
CO
Cu
CU
CO
VJ
cu
£>
r-l
•H
CO
1
T3
r-l
O
o
preparation wet air pollution
o
•r-l
4J
r*1
r—f
O
J-l
4-1
O
cu
r-l
W
X-N
•
Jg
•
CM
*~s
i
r-l
O
4J
c
O
O
C
o
4J
CO
CJ
•I-l
U-l
•I-l
}_l
rj
CM
j_i
cu
4J
M
Pn
ide reduction spent solution
cells wet air pollution contro
als wash water
j-i
o
r-4
43
CJ
J-l
cu
^
r—f
•I-l
CO
X-N
jrj
•
CM
>»x
O
.,-1
4J
>•>
r-l
O
J-l
4J
O
cu
r-H
W
x-s
•
*r|
•
CM
•^^
4-)
CO
5^
, J-i
O
V-i
cu
I-l
•I-l
CO
X-N
2
•
CM
N— '
01
4-1
CO
cu
' CO
c
•I-l
!-i VJ
0)
T3 4->
§1
CO 4-1
cO cO
T3 00
•-i C
CJ -H
CO C
cO
CO CU
, CO
a cu
o
rJ O
O J-i
a.
cu
CO J-l
d co
CUr-l
r
004J
3 J-j
O cO
jj a
43
H CO
*
33
-------
CO
a
3
O
O
QS
Oi
S
34
-------
H20-
Beneficiation
Product
To Atmosphere
1
Stack
Gas
Cooling
Calciner Wet Air
Pollution Control
(Multistage)
Stack
Gas
Condenser
Liquid Hg Product
Hg Vapor
Calcining or
Roasting Furnace
•
Condenser
Slowdown
Calcined Ore
Waste Product
Clean Mercury
Product
Figure III-2
PRIMARY MERCURY PRODUCTION PROCESS
35
-------
en
co
i
CU
o cn
w H
PM
M O
Pd O
PM W
H
pq
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION IV
SUBCATEGORIZATION
As discussed in Section IV of the General Development Document,
the nonferrous metals manufacturing category has been subcate-
gorized to take into account pertinent industry characteristics,
manufacturing process variations, and a number of other factors
which affect the ability of the facilities to achieve effluent
limitations. This section summarizes the factors considered
during the designation of the primary precious metals and mercury
subcategory and its related subdivisions. Production normalizing
parameters for each subdivision will also be discussed.
FACTORS CONSIDERED IN SUBCATEGORIZATION
The following factors were evaluated for use in subcategorizing
the nonferrous metals manufacturing category:
1. Metal products, co-products, and by-products;
2. Raw materials;
3. Manufacturing processes;
4. Product form;
5. Plant location;
6. Plant age;
7. Plant size;
8. Air pollution control methods;
9. Meteorological conditions;
10. Treatment costs;
11. Nonwater quality aspects;
12. Number of employees;
13. Total energy requirements; and
14. Unique plant characteristics.
Evaluation of all factors that could warrant subcategorization
resulted in the designation of the primary precious metals and
mercury subcategory. Three factors were particularly important
in establishing these classifications: the type of metal pro-
duced, the nature of the raw material used, and the manufacturing
processes involved.
In Section IV of the General Development Document, each of these
factors is described, and the rationale for selecting metal prod-
uct, manufacturing process, and raw materials as the principal
factors used for subcategorization is discussed. On this basis,
the nonferrous metals manufacturing category (phase II) was
divided into 21 subcategories, one of them being primary precious
metals and mercury.
37
-------
FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY
The factors listed previously were each evaluated when consider-
ing subdivision of the primary precious metals and mercury sub-
category. In the discussion that follows, the factors will be
described as they pertain to this particular subcategory.
The rationale for considering further subdivision of the primary
precious metals and mercury subcategory is based primarily on
differences in the production processes and raw materials used.
Within this subcategory, a number of different operations are
performed, which may or may not have a water use or discharge,
and which may require the establishment of separate effluent
limitations. While primary precious metals and mercury is still
considered a single subcategory, a more thorough examination of
the production processes has illustrated the need for limitations
and standards based on a specific set of waste streams. Limita-
tions will be based on specific flow allowances for the following
subdivisions:
1. Smelter wet air pollution control,
2. Silver chloride reduction spent solution,
3. Electrolytic cells wet air pollution control,
4. Electrolyte preparation wet air pollution control,
5. Silver crystal wash water,
6. Gold slimes acid wash and water rinse,
7. Calciner wet air pollution control,
8. Calcine quench water,
9. Calciner stack gas contact cooling water,
10. Condenser blowdown, and
11. Mercury cleaning bath water.
These subdivisions follow directly from differences within the
three distinct production stages of primary precious metals and
mercury.
The smelting of precious metals bearing concentrates to produce
Dore metals gives rise to the first subdivision: the smelter wet
air pollution control wastewater. If any remelt furnaces are
used in the process, the resulting off-gases are usually combined
with smelter off-gases for air pollution control. Thus, the
smelter wet air pollution control subdivision represents the wet
air pollution control wastewater for both smelters and remelt
furnaces. The next two subdivisions result from the Miller
process (electrolytic refining of gold) for purifying high silver
content Dore metal. The electrolytic cells scrubber wastewater
is the principal waste stream, but spent solution from silver
reduction is also discharged.
38
-------
The electrolytic refining of silver from Dore metal gives rise to
the next three subdivisions. The washing of electrolysis prod-
ucts (silver crystals and gold slimes) creates two waste streams
that can potentially be discharged. The fourth subdivision is
created by the wet scrubber used to control air emissions from
the electrolyte preparation stage.
The last five subdivisions result from the production of primary
mercury. The treatment of calciner off-gases by wet scrubbing
gives rise to the first of these subdivisions. Waste streams may
also result from the quenching of calciner wastes to reduce their
temperature prior to disposal and the cooling of calciner off-
gases before discharge from the stack. During condensation of
the vaporized mercury, the condensation of a. water fraction can
occur and this condenser blowdown is a possible waste stream.
After condensation the liquid mercury may be further purified by
use of cleaning baths. This cleaning operation is also a
potential source of wastewater.
OTHER FACTORS
The other factors considered in this evaluation either support
the establishment of the 11 subdivisions or were shown to be
inappropriate bases for subdivision. Air pollution control
methods, treatment costs, and total energy requirements are
functions of the selected subcategorization factors—metal
product, raw materials, and production processes. Therefore,
they are not independent factors and do not affect the subcate-
gorization which has been applied. As discussed in Section IV of
the General Development Document, certain other factors, such as
plant age, plant size, and the number of employees, were also
evaluated and determined to be inappropriate for use as bases for
subdivision of nonferrous metals plants.
PRODUCTION NORMALIZING PARAMETERS
As discussed previously, the effluent limitations and standards
developed in this document establish mass limitations on the dis-
charge of specific pollutant parameters. To allow these regula-
tions to be applied to plants with various production capacities,
the mass of pollutant discharged must be related to a unit of
production. This factor is known as the production normalizing
parameter (PNP).
In general, for each production process which has a wastewater
associated with it, the actual mass of precious metal or mercury
product produced will be used as the PNP. Thus, the PNPs for the
11 subdivisions are as follows:
39
-------
Subdivision
PNP
4.
Smelter wet air pollution
control
Silver chloride reduction
spent solution
Electrolytic cells wet air
pollution control
Electrolyte preparation
wet air pollution control
5. Silver crystal wash water
6. Gold slimes acid wash and
water rinse
7. Calciner wet air pollution
control
8. Calcine quench water
9. Calciner stack gas contact
cooling water
10. Condenser blowdown
troy ounce of gold and silver
smelted
troy ounce of silver reduced
in solution
troy ounce of gold refined
electrolytically
troy ounce of silver in elec-
trolyte produced
troy ounce of silver crystals
washed
troy ounce of gold slimes
washed
kkg of mercury condensed
kkg of mercury condensed
kkg of mercury condensed
kkg of mercury condensed
11. Mercury cleaning bath water kkg of mercury condensed
Other PNPs were considered. The use of production capacity
instead of actual production was eliminated from consideration
because the mass of the pollutant produced is more a function of
true production than of installed capacity. The use of some com-
mon intermediate (i.e., gold and silver cathodes or silver chlo-
ride) as a basis for PNPs for all processes was rejected since
not all plants follow the same production path to get to the
specific end-product. Additionally, some plants divert part of
their intermediate products and sell them instead of processing
all input raw materials to one final product. If an "end-
product" were chosen as the PNP, plants that had these upstream
diversions would be allowed to discharge more per mass of product
than their competitors who did not.
40
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION V
WATER USE AND WASTEWATER CHARACTERISTICS
This section describes the characteristics of the wastewaters
associated with the primary precious metals and mercury subcate-
gory. Water use and discharge rates are explained and then
summarized in tables at the end of this section. Data used to
characterize the wastewaters are presented.. Finally, the
specific source, water use and discharge flows, and wastewater
characteristics for each separate wastewater source are
discussed.
Section V of the General Development Document contains a detailed
description of the data sources and methods of analysis used to
characterize wastewater from the nonferrous metals manufacturing
category. To summarize this information briefly, two principal
data sources were used: data collection portfolios (dcp) and
field sampling results. Data collection portfolios contain
information regarding wastewater flows and production levels.
In order to quantify the pollutant discharge from primary pre-
cious metals and mercury plants, a field sampling program was
conducted. A complete list of the pollutants considered and a
summary of the techniques used in sampling and laboratory analy-
ses are included in Section V of the General Development Docu-
ment. Samples were analyzed for 124 of the 126 toxic pollutants
and other pollutants deemed appropriate. (Because the analytical
standard for TCDD was judged to be too hazardous to be made gen-
erally available, samples were never analyzed for this pollutant.
Samples were also not analyzed for asbestos. There is no reason
to expect that TCDD or asbestos would be present in nonferrous
metals manufacturing wastewater.) A total of two plants were
selected for sampling in the primary precious metals and mercury
subcategory. In general, the samples were analyzed for three
classes of pollutants: toxic organic pollutants, toxic metal
pollutants, and criteria pollutants (which includes both
conventional and nonconventional pollutants).
As described in Section IV of this supplement, the primary
precious metals and mercury subcategory has been split into 11
subdivisions or wastewater sources, so that the proposed regula-
tion contains mass discharge limitations and standards for 11
unit processes discharging process wastewater. Differences in
the wastewater characteristics associated with these subdivisions
are to be expected. For this reason, wastewater streams corre-
sponding to each subdivision are addressed separately in the
discussions that follow. These wastewater sources are:
41
-------
1. Smelter wet air pollution control,
2. Silver chloride reduction spent solution,
3. Electrolytic cells wet air pollution control,
4. Electrolyte preparation wet air pollution control,
5. Silver crystal wash water,
6. Gold slimes acid wash and water rinse,
7. Calciner wet air pollution control,
8. Calcine quench water,
9. Calciner stack gas contact cooling water,
10. Condenser blowdown, and
11. Mercury cleaning bath water.
WASTEWATER FLOW RATES
Data supplied by dcp responses were evaluated, and two flow-to-
production ratios, water use and wastewater discharge flow, were
calculated for each stream. The two ratios are differentiated by
the flow value used in calculation. Water use is defined as the
volume of water or other fluid required for a given process per
mass of product and is therefore based on the sum of recycle and
make-up flows to a given process. Wastewater flow discharged
after pretreatment or recycle (if these are present) is used in
calculating the production normalized flow—the volume of waste-
water discharged from a given process to further treatment,
disposal, or discharge per mass of product produced. Differences
between the water use and wastewater flows associated with a
given stream result from recycle, evaporation, and carryover on
the product. The production values used in calculation corre-
'spend to the production normalizing parameter, PNP, assigned to
each stream, as outlined in Section IV. As an example, calcine
quench water flow is related to the production of the refined
mercury. As such, the discharge rate is expressed in liters of
quench water per metric ton of mercury produced (gallons of
quench water per ton of mercury).
The production normalized discharge flows were compiled and sta-
tistically analyzed by stream type. These production normalized
water use and discharge flows are presented by subdivision in
Tables V-1 through V-11 at the end of this section. Where appro-
priate, an attempt was made to identify factors that could
account for variations in water use and discharge rates. These
variations are discussed later in this section by subdivision. A
similar analysis of factors affecting the wastewater flows is
presented in Sections X, XI, and XII where representative BAT,
NSPS, and pretreatment flows are selected for use in calculating
the effluent limitations.
The water use and discharge rates shown do not include nonprocess
wastewater, such as rainfall runoff and noncontact cooling water.
42
-------
WASTEWATER CHARACTERISTICS DATA
Data used to characterize the various wastewaters associated with
primary precious metals and mercury production come from two
sources—data collection portfolios and analytical data from
field sampling trips.
DATA COLLECTION PORTFOLIOS
In the data collection portfolios, the primary precious metals
and mercury plants that generate wastewater were asked to specify
the presence or absence of toxic pollutants in their wastewater.
In most cases, the plants indicated that the toxic organic pollu-
tants were believed to be absent. However, two of the plants
stated that they either knew or believed the metals to be
present. The responses for asbestos, cyanide, and the metals are
summarized below:*
Pollutant Known Present Believed Present
Antimony 0 0
Arsenic 1 0
Asbestos 0 1
Beryllium 0 0
Cadmium 1 0
Chromium 1 0
Copper 1 0
Cyanide 1 0
Lead 1 0
Mercury 2 1
Nickel 1 0
Selenium 1 0
Silver 1 0
Thallium 0 0
Zinc 1 0
Although asbestos was reported as believed present by one plant,
the trip report from this facility stated it was the mineral
cummingtonite which was present and not asbestos. Although the
two minerals have some similarities such as similar chemical
formulas, cummingtonite is not listed by EPA as a toxic
pollutant.
*Six plants which produce primary precious metals and mercury
have been omitted due to lack of data.
43
-------
FIELD SAMPLING DATA
In order to quantify the concentrations of pollutants present in
wastewater from primary precious metals and mercury plants,
wastewater samples were collected at two plants. The analytical
results from one of these two plants are not presented here
because they are claimed to be confidential by the plant. A dia-
gram indicating the sampling sites and contributing production
processes at the non-confidential plant is shown in Figure V-1
(at the end of this section).
Raw wastewater data are summarized in Tables V-12 through V-15
(at the end of this section). Analytical results for the com-
bined stream of smelter scrubber water and Miller electrolysis
cell scrubber water as well as spent solution from silver
reduction are contained in the confidential record. Table V-12
presents data for each of the three stages of the calciner
scrubber system. Tables V-13, V-14, and V-15 present sampling
data for calcine quench water, calciner stack gas cooling water,
and mercury cleaning bath water, respectively. Note that the
stream numbers listed in the tables correspond to those given in
the individual plant sampling site diagram, Figure V-1. Where no
data are listed for a specific day of sampling, the wastewater
samples for the stream were not collected.
Several points regarding these tables should be noted. First,
the data tables include some samples measured at concentrations
considered not quantifiable. The base-neutral extractable, acid
extractable, and volatile organics generally are considered not
quantifiable at concentrations equal to or less than 0.010 mg/1.
Below this concentration, organic analytical results are not
quantitatively accurate; however, the analyses are useful to
indicate the presence of a particular pollutant. The pesticide
fraction is considered not quantifiable at concentrations equal
to or less than 0.005 mg/1.
Second, the detection limits shown on the data tables for toxic
metals and conventional and nonconventional pollutants are not
the same in all cases as the published detection limits for these
pollutants by the same analytical methods. The detection limits
used were reported with the analytical data and hence are the
appropriate limits to apply to the data. Detection limit varia-
tion can occur as a result of a number of laboratory-specific,
equipment-specific, and daily operator-specific factors. These
factors can include day-to-day differences in machine calibra-
tion, variation in stock solutions, and variation in operators.
Third, the statistical analysis of data includes some samples
measured at concentrations considered not quantifiable. For data
considered as detected but below quantifiable concentrations, a
44
-------
value of zero is used for averaging. Toxic organic, nonconven-
tional, and conventional pollutant data reported with a "less
than" sign are considered as detected, but not further quantifi-
able. A value of zero is also used for averaging. If a pollu-
tant is reported as not detected, it is assigned a value of zero
in calculating the average. Finally, toxic metal values reported
as less than a certain value were considered as below quantifica-
tion, and consequently were assigned a value of zero in the
calculation of the average.
Finally, appropriate source water concentrations are presented
with the summaries of the sampling data. The method by which
each sample was collected is indicated by number, as follows:
1 One-time grab
2 Manual composite during intermittent process operation
3 8-hour manual composite
4 8-hour automatic composite
5 24-hour manual composite
6 24-hour automatic composite
WASTEWATER CHARACTERISTICS AND FLOWS BY SUBDIVISION
Since primary precious metals and mercury production involves 11
principal sources of wastewater and each has potentially differ-
ent characteristics and flows, the wastewater characteristics and
discharge rates corresponding to each subdivision will be
described separately. A brief description of why the associated
production processes generate a wastewater and explanations for
variations of water use within each subdivision will also be
discussed.
SMELTER WET AIR POLLUTION CONTROL
Six of the eight plants in this subcategory smelt or roast the
precious metal-bearing raw material. Only three of those facil-
ities, however, use a wet air pollution control device to control
air emissions from the furnace. Two of these devices are scrub-
bers, while one (at plant 1003) is an electrostatic precipitator
(ESP). Two plants practice dry air pollution control, and one
plant does not practice any air pollution control. The produc-
tion normalized water use and discharge rates are presented in
Table V-1 in liters per troy ounce of gold and silver smelted.
Analytical data for the combined smelter wet air pollution con-
trol and electrolytic cells wet air pollution control waste
streams are contained in the confidential record. The data show
that this wastewater contains treatable concentrations of toxic
metals, suspended solids, and oil and grease.
45
-------
SILVER tILORIDE REDUCTION SPENT SOLUTION
Only on plant in the subcategory uses the Miller process to
refine are metal. Spent solution from the reduction of silver
chlorid to silver metal is a potential waste stream. The pro-
duction lormalized water use and discharge flows are presented in
Table V 2, in liters per troy ounce of silver reduced in
solutio .
Samplin data for spent solution are contained in the
confide tial record. This waste stream is very acidic (pH 0.9)
and the sampling data indicate that high concentrations of toxic
metals, suspended solids, and oil and grease are present.
ELECTRC YTIC CELLS WET AIR POLLUTION CONTROL
The use of wet scrubbers to control emissions from electrolytic
cells i practiced at only one plant in this subcategory. Pro-
duction normalized water use and discharge rates are presented in
Table V 3. Sampling data for the combined smelter wet air pollu-
tion cc trol and electrolytic cell wet air pollution control
waste s ream are contained in the confidential record. The data
show th s waste stream to contain treatable concentrations of
toxic m tals, suspended solids, and oil and grease.
ELECTRC YTE PREPARATION WET AIR POLLUTION CONTROL
The sil er nitrate electrolyte used in the electrolytic refining
of Dore metal is prepared by combining pure silver with nitric
acid. cie one facility that uses this process also uses a wet
scrubbe to control air emissions from the preparation step,
thereby generating a waste stream. Production normalized water
use and discharge rates are presented in Table V-4 in liters per
troy ou ce of silver in electrolyte produced. No sampling data
were ga tiered for this waste stream; however, it is expected to
have ch racteristics similar to those of the combined raw waste-
waters rom smelter wet air pollution control and the electroly-
tic eel scrubber. This waste stream, therefore, is expected to
contain treatable concentrations of suspended solids, toxic
metals, and oil and grease.
SILVER RYSTAL WASH WATER
After e ectrolytic refining of Dore metal, the silver which is
deposit d upon the cathode is removed and washed. Production
normali ed water use and discharge rates for this waste stream
are pre ented in Table V-5, in liters per troy ounce of silver
crystal washed.
46
-------
Although no samples of this waste stream were analyzed, it is
expected that its characteristics will be similar to wastewater
from the secondary silver subcategory, and is contained in the
nonferrous phase I public record for that subcategory (see stream
40 at secondary silver plant A). The data show treatable concen-
trations of toxic metals, suspended solids, and oil and grease.
GOLD SLIMES ACID WASH AND WATER RINSE
Gold slimes remaining in the canvas anode bag from electrolytic
refining of Dore metal contain significant amounts of gold and
some silver. The gold slimes are washed with nitric acid and
water to remove the silver by dissolving it into solution. These
wash waters are currently sent to a cementation step, and repre-
sent a potential source of wastewater. Production normalized
water use and discharge rates for this subdivision are presented
in Table V-6 in liters per troy ounce of gold slimes washed. No
sampling data were collected for this waste stream; however, it
is expected to have characteristics similar to those of gold
precipitation and filtration (a very similar process step) waste-
water in the secondary precious metals subcategory. This waste
stream, therefore, is expected to contain treatable concentra-
tions of toxic metals and suspended solids.
CALCINER WET AIR POLLUTION CONTROL.
One of the two plants producing primary mercury uses a water
scrubber to control air emissions from the calciner. This plant
uses a series of three scrubbers (Venturi, Impinger, and S02).
Sampling data for the wastewater generated by these scrubbers are
presented in Table V-12. The scrubber waters have a low pH (2.3
to 2.6) and contain treatable concentrations of toxic metals such
as lead, mercury, thallium and zinc, and suspended solids. The
production normalized water use and discharge rates are shown in
Table V-7.
CALCINE QUENCH WATER
One mercury producer uses water to quench the waste calcines from
the mercury roaster to allow faster handling and disposal of
these materials. Table V-8 presents the production normalized
water use and discharge rates for this waste stream. Sampling
data are summarized in Table V-13 and show high concentrations of
toxic metals such as arsenic, mercury and zinc, and suspended
solids. This waste stream has a nearly neutral pH of 6.8.
CALCINER STACK GAS CONTACT COOLING WATER
One facility uses contact cooling water to reduce the temperature
of the calciner off-gases before releasing them to the atmo-
sphere. Sampling data for this waste stream are summarized in
47
-------
Table V-14. This waste stream has a pH of 2.5 and contains
treatable concentrations of mercury and suspended solids. Pro-
duction normalized water use and discharge rates are given in
Table V-9.
CONDENSER SLOWDOWN
When mercury is vaporized in the calciner, some water contained
in the Cinnibar or gold ore may also be vaporized. The condensa-
tion of mercury for recovery may result in the condensation of
some water which is discharged as condenser blowdown. Table V-10
summarizes the production normalized water use and discharge
rates for this waste stream.
Although no sampling data were collected for this waste stream,
it is expected to be very similar to the discharge from the
mercury cleaning bath. The data are presented in Table V-15, and
the condenser blowdown stream is expected to contain treatable
concentrations of mercury and suspended solids.
MERCURY CLEANING BATH WATER
Condensed mercury is processed for the removal of impurities by
being passed through a water cleaning bath. This Waste stream
contains treatable concentrations of mercury and suspended solids
and very low concentrations of other toxic metals. The sampling
data for this waste stream are presented in Table V-15. Produc-
tion normalized water use and discharge rates are provided in
Table V-11.
48
-------
Table V-1
WATER USE AND DISCHARGE RATES FOR
SMELTER WET AIR POLLUTION CONTROL
(liters/troy ounce of gold and silver smelted)
Plant Code
1131*
1003
1137
1068
1158
Percent
Recycle
76
90
100
Dry
Dry
Production
Normalized
Water Use
25.8
5.3
8.41
Production
Normalized
Discharge
Flow -
6.2
0.53
0
*No operations conducted in 1982; water use and discharge rates
based on projected 1983 figures.
49
-------
Table V-2
WATER USE AND DISCHARGE RATES FOR
SILVER CHLORIDE REDUCTION SPENT SOLUTION
(liters/troy ounce of silver reduced in solution)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1003 0 0.4 0.4
50
-------
Table V-3
WATER USE AND DISCHARGE RATES FOR
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL
(liters/troy ounce of gold refined electrolytically)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1003 0 198 198
51
-------
Table V-4
WATER USE AND DISCHARGE RATES FOR
ELECTROLYTE PREPARATION WET AIR POLLUTION CONTROL
(liters/troy ounce of silver in electrolyte produced)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1160 0 0.05 0.05
52
-------
Table V-5
WATER USE AND DISCHARGE RATES FOR
SILVER CRYSTAL WASH WATER
(liters/troy ounce of silver crystals washed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1160 0 0.29 0.29
53
-------
Table V-6
WATER USE AND DISCHARGE RATES FOR
GOLD SLIMES ACID WASH AND WATER RINSE
(liters/troy ounce of gold slimes washed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1160 0 4.0 4.0
54
-------
Table V-7
WATER USE AND DISCHARGE RATES FOR
CALCINER WET AIR POLLUTION CONTROL
(liters/kkg of mercury condensed)
Plant Code
1124
(Venturi)
1124
(Impinger)
1124
(S02)
TOTAL
Percent
Recycle
16
16
16
16
Production
Normalized
Water Use
4,607
7,536
209.524
221,667
Production
Normalized
Discharge
Flow
3,870
6,330
176.000
186,200
55
-------
Table V-8
WATER USE AND DISCHARGE RATES FOR
CALCINE QUENCH WATER
(liters/kkg of mercury condensed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1124 0 17,600 17,600
56
-------
Table V-9
WATER USE AND DISCHARGE RATES FOR
CALCINER STACK GAS CONTACT COOLING WATER
(liters/kkg of mercury condensed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1124 0 4,150 4,150
57
-------
Table V-10
WATER USE AND DISCHARGE RATES FOR
CONDENSER SLOWDOWN
(liters/kkg of mercury condensed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
1068 ' 0 13,800 13,800
1124 Dry
58
-------
Table V-11
WATER USE AND DISCHARGE RATES FOR
MERCURY CLEANING BATH WATER
(liters/kkg of mercury condensed)
Production
Production Normalized
Percent Normalized Discharge
Plant Code Recycle Water Use Flow
'1124 0 1,400 1,400
59
-------
CN
1
^
(U
rH
.Q
CO
H
<2
H
>
e
CO CU
V4 O
U 0
CO
O i— CN O T- CN O i— CN O <— CN O i— CN O i— CN
^^-^ ^^f-^ ^d"
G
O
0
•i-l
4->
cO
•
i^
i —
V4
CU
CU
o*
o
o
*
o
CN
'—
60
-------
•5"
CD
j)
C
4->
G
O
v— X
CM
t—
1
^
CO
-0
CO
H
^
H
^3
Q
o
i— <
j
0,
"s*
^
co
ai
s
W
H
U
=Q
3
CO
>*
05
£3
o
o5
a
S
Q
S5
J
H
S3
O
°
S3
o
r-i os!
Cj TT^
OH
rJ«J
t-4 3
O W
PM H
CO
OS
CO
1.
M
4-1
c
co
o
c
O
CJ
CO
r-l
C3
CO
CO
fl
CO
S-4
4J
co
CO
Q
Z
CO
Q
r—
rrt
w
a
CO
o
o
CO
•1-
Q.
J;^
H
co
"O
O
O
4J
C
4-1
J3
r-l
rH
O
PM
CM CM CO CO
oo -3* miAio oo
CM O O OO OOO OO
CM O O OOO OOO OO
\S \/ ^O CO NX W W
CO T-
CMCMCM vOvO\O COCO
OOO ^ ^— T— LOLOLO OO
OOO OOO OOO OO
OOO OOO OOO OO
\S \/ \S VVV W
O »- CM O T— CM O t- CM O T-
>^^s^ ^-^"-^ ^'-^'•J' ^3°
•H
CO
•
\o
CN
T—
CM
T- CM O
^O r— O
OOO
V
CM CM CM
OOO
OOO
OOO
VVV
O r-
-------
^
CU
c
4->
c
o
^
v-x
CN
1
^
cu
H O H
oi J >
cO
Q
t—
cd1
Q
(U
O
l-i
O
cn
•i—
(U
>>
f— i
•S
o
CJ
00 r— CO C^ CTi f~»
lOLOLO T— CN LO OOCN
ooo ooo ooo
OOO i—-r-r- OOO OOO OOO CN CO T- O m t—
cr> o> co \/\x\/ \xvv vv minm r»~ r^ ^* ^ ^^
ooo ooo ooo
i— >— T— OOO OOO OOO OOO CNCNCN OOO
i— r— T—
O T- CN Oi— CN Or-CN O T- CN O^-CN O-r-CN O T— CN
~^ ~^ ^ ^ >^ "^ ^ -^">
4J
•^ a cu
§^o
"^
T3 cO 8 -^ O CJ O
•T-l K^ ^3 }.) V-l r~l i— 1
O r-l ,-1 CO O CO J3
cO CO cO ,£> Z3 O O
62
-------
^^N
•o
cu
C
•r-l
4J
C
o
o
v-/
CM
1
>
0)
4 I-J
05 0
SH
M 25
HO
O
QQ 73
3 O
CO i— i o5
H W
>" 3 H
•as rJ >
cd
Q
>,
cd
Q
Ol
o
5-1
3
O
CO
CU
—1 •»-
P, cu
S cx
Cd r*1
CO H
B
01 T3
5-1 O
4J CJ
CO
000
000
00 «-
O
co
63
-------
s
CO
O
4-J
C
a*
o
c
o
u
CO
Q
0)
CN CM CN
ID in in
ooo
ooo
CO CO CO
ooo
ooo
CN CN CN
OOO
OOO
OOO
ooo
ooo
r*^ co r^
OOO
in in ur»
OOO
CNCNCN
OOO
V W
m m m
ooo
000
OOO
vx/v
OOO
vvv
000
ooo
co oo r^
000
r-. r>- r-
^O ^D ^O
ooo
V W
ooo
ooo
ooo
V V N/
CN CN CN
000
ooo
OOO
ooo
\S N/ V
4J
c
o
o
ctf J
PL, <1J
e a
co >.
co H
CM
I
S
cO 0>
5-i O
•U O
CO
O i— CN O T- CN O r- CN O^— CN O r-
O r- CM
13
C
O O
o
o
05
O-i
co
4J
C
4-)
C
o
a,
cO
C
o
•i-4
4J
C
cu
o
cj
C
o
z
CQ
c
•H
4-1
cd
4J
CO
H
CO
o
CO
CO
4->
o
4->
I
•r-l
T3
C
cO
>
S-i
4->
4-1
64
-------
'Q
0)
*3
C
4J
C
o
o
S_ X
CN
T—
1
>
CU
^
H
^
O
Z
(-1
J
PM
*yj
^3
CO
aS O
8 H
W Z
HO
O
oQ z
3 O
CO M OS
^J **~\ f i
i^1 *— ' pH
&* h-3
C
0)
o
C
o
CO
00
cO
Q
>.
Q
T—
>>
cO
Q
OO OO >>O
• • •
t— t— T- O LO T- CM CN CN
V \/ \/ OO N/
CU
0
3
O
CO
o\a\~i
CO H
a
cO CU
M O
4-1 U
co
O «— CN O i— CN O i— CN
•"d" -^ ^" ^d" -J" * CO
aS 4J
23 c
2, 4-> cO
i-1 C 4J
aS co 3
O-i 4-1 i— 4
t-» ^j
^j f^^
r-l O
iH CM
O
OH r-l
CO
C
O
•r-l
4J
C
^
C
o
o
CO
13
•r-l
r-l
O
CO
T3
CU CU
CO 13
CO C
CU 0)
r-l CU
00 CO
*3
T3 CO
C
CO r-l
CO
r-l 4-)
•H O
O 4-1
s^
CO
•U
•H
c
rQ
J_|
ffl
T3
C
cO
4J
CO
pr|
a.
cO
V-i
00
CU
e
CU
c§
CU
TJ
O
CO
ex
CU
r-l
a
cO
CO
65
-------
(f)
0)
5
cO
H
^
H
C
0)
0
C
o
CJ
(U
r-l
a
co
a
CO
Q
CM
>*
CO
Q
^—
>,
cO
Q
CU
0
VJ
jj
O
CO
•H-
d)
rt
i-^
CU
P^ CO
O »— vO ON O 00 mo
o ooocoon%
O cO C
t^i -U O
s a
rH -H
r-l 4J
0 C
O-i cO
0
•rH •
X -*
o <-
p-l »-
a
O -r-l
•H r-4
C r^
0) >»
CQ J-l
V-i 0)
cO -Q
in r~~
r— T—
B
^
•r-l
a
cO
O
oo
r—
cO
4J
O
4_)
v^
B
•r-l
S
o
u
X!
O
OS
^~
r-l
CU
a.
ex
o
o
o
CM
'O
cO
cu
r-l
CM
CM
>~,
^.1
3
O
i_i
CU
a
CO
CM
r-l
CU
K^
CJ
•r-l
C
^
CM
•r-l
C
0)
r-l
CU
CO
in
CM
r-l
0)
^
r— 1
•r-l
CQ
VO
CM
a
••-<
rH
r-l 0
cO C
_Cj T-l
4-J N
r~ co
CM CM
66
-------
/-s
T3
CU
d
c
•H
4-1
C
o
u
v^
en
T—
1
>
CU
I—I
43
cO
H
<
a3
8
a
H
<:?*$
o w
«H
3*ac<
&VZ
32 W
O W H
03 3 CO
M O",
CO
Q
CM
>>
cO
Q
*~
!>,
CO
Q
cu
o
r-J
d
o
co
cu
r-l -1-
cx cu
a a
cO f^
CO H
a
CO CU
CU T3
VJ O
4-1 CJ
CO
r- 00
V
c
o
o
c
o
a
>!
4-J
•i-l
r^ C
4J -H
•t-l r-l
T3 CO
"-I 3(!
O r-l
cO fO
|
c
•r-l
a
3
r-l
CO
a
d
•r-l
r-l
CO
43
c
o
V
O
43
a
d
•r-l
0
r-l
cO
O
CU
TJ
•H
r-l
O
r-l
43
O
4J
r-l
CO
43
O
O
CU
T3
•H
r-l
O
d
r-l
IW
c
o
v-<
•r-l
1
•H
CO
CU
c
00
CO
a
CU
CO
cu
C
cO
00
c
cO
@
g
cu
T3
43
>!
r-l
O
a
67
-------
o
OH
CO
OS
M
B
o
C
o
u
ro
CO
Q
CO
cO
01
CM
m
oo
O
O
O
O
0\
CS O
»- O
o
CN t—
m
on
CN O
r- O
O
O
o
v
o
v
o
o
o
V
«— o
V O
CO
V V
0)
c
4-1
c
o
p
CQH
CO ^ Cx3
SH 3-
C
o
o
c
o
z
01
S 4->
S cO
•H <4-l
-O r-1
O 3
CO CO
c
cO
4-)
CO
H
CO
-a
o
CQ
cO
4->
o
B
TD
cO
c
CO
CO
4J
c
cO
4J
o
OH
cO
4J
c
0)
c
o
p
cO
u
00
0)
s
•r4
U
a>
CO
cO
00
§
co
o
CO
T3
0)
C
Ol
ex
CO
CQ
cO
•U
o
4J
CO
4J
cO
c
cO
u
CO
01
T3
o
o
01
ex.
0)
r-l
a
B
cO
CO
68
-------
<^
9-1
J S
8i
H J
• 3 53 W
CJ OH
0) aS cj CO
,-) W ^ OOOOOO
4JQ OOOOOO
C V V V V \/
01
0
c
O 0) CO CO
CJO OT-,-,— CM,-
V4 O O O O O CO
o o o o o' o* o
CO V V V V
n
t-l •»-
CX 0)
C(J r^l
CO H
E
cd 0)
01 T3
^ _j rj >j ^«^ >^i ""^r ^3" ^>t"
co
^v
4J rd
C 4J
CO O
4-> 4J
d w ^-^
r-l C >S d 0
O Otf C O -r^ 0 0
CM 4-i o -i-i i— i d 1-1 i-i
r3 -S oi ">> "B o ex
r— I 4J CO W ^ M Qi
O C VJ OJ cd j2 O
CM cfl oj JD o o o
o
•i-4 • • • • • •
X <(• m p^ oo cr> o
O 1— <— T- T- T— tf
o m o o o CM
o <— o o o o o
O CM O O O O O
V V \/ V V
CM vO CO T— OI
o T- m o o o T-
o o o o o o o
o o o o o o o
V V NX V V V
CO ^O CO CO CO CO CO
a s
Jj r^ -t-l ' V< -H
*O O J^ 0> > ,-H CJ
Cd J"4 O r-^ rH Cd Ci
Ci) Q) *i-l 0) *H (^ *r^
^ 8 C CO CO 4J N
• •••••«
CM co "^ ^/^ v*o r*^ cjo
CM
-------
/•^
tj
0)
d
c
•r-l
I |
^J
c
o
o
v^<
•o-
,—
1
>
(U
—1
_o
cO
EH
"5
as
So
a
W. <
HH
HJ
<
od
y}
i— i
oS
Oi
x->
rH
00
CO
c
O
•r-l
4J
CO
J-l
4J
c
CU
O
c
o
o
OO
>,
cO
Q
CN
>i
rrt
CO
Q
r—
>i
CO
Q
r~» o\ vo
o ,
CO H
s
cO (U
-i O
4J O
co
OOOOOOOOOOOOOOOOOO
^t^t-^^t^^j-o.^.^
CO
1 1
4J
c
cO
4-1
3
4J
c
cO
4-)
s
r-l
i-l
O
Oi
r-4
rH
o
O4
r-l
CO
c
o
1
•p^
4J ^
C 4J
cu •n S cu (U
> >. C 3 B T) T3
C -W -H C B d --H 4J "-I
O -^ r-l -i-l 3 C -H V4 rH J-l
OtScOB-iHOOOcOO
C'^^dJ-t Wr-HrH^S
OOr-l— ICOOCOJSOr-l
acOcOcO^D.QOOOiW
CTi CS
OO r- O
0000
• • • •
O QO O O
\/ \/
CM
LO • T- O
o o o o
• • • •
O CO O O
NX V
OO OO OO OO
i
0 00 C rH
VJ cO cO O
•r4 e B B
70
-------
^-s
T5
CU
3
C
•r-l
4J
c
O
O
V— X
o-
T™»
1
>
CO
r-l
<
H
£
r— ^
O
z
r-l
J
CM
a 05
< 03
CO EH
<3
>-" 3
05
SO
'Z
f_T uj
LX4 i^
H J
Hi
cO
Q
>,
CO
Q
CD
O
U
3
O
CO
0)
rH -r-
cx cu
S a
cO (^
CO EH
S
cO CO
CO
CO
en
o
o
CO
CN
o
m
CM
o
V
O
V
m
O
o
m
o
o
•
o
V
o
oo
00
o
o
•
o
\s
CN
O
O
*
O
\s
in
•
CM
CO CN
O O
o o
o-
V
o
V
V V
CO CO
CO
CO CO CO CO
CO CO
CO
^s
CO
H
\_^
CO
T3
.H
rH
O
CO
rH
CO
4J
O
4J
co
J-)
G
cO
4J
3
rH
rH
O
04
rH
CO
C
O
S -H
3 £3 4-i
•H 3 C
*O iH CU
CO rl >
C -U C
CO 4J O
> >s 0
(1)
CO
cO
cu
U
00
T3
c
CO
rH
•H
O
CO
T3
•H
— <
O
CO
T3
(U
T3
C
(U
(X
CO
3
CO
rH
CO
4J
O
4->
s~\
CO
4-)
•H
C
3
TJ
V-i
cO
-o
C
cO
4->
CO
v^
33
cx
(U
TJ
O
OJ
ex
01
r-l
a
I
CO
71
-------
,_
1
^
0)
r-l
43
cd
H
<
H
C3C5C3C>CDOJ
V V V V V V
0)
0
}_l
r4
o
CO
CO CO CM ^O
Or-r-t-CMt-Ot—
OOOOOCOOO
oooooooo
V V V V V
(U
r-l 4-
(X (U
S(-v
(-*•
CO H
S
CUT)
r-l O
4J O
CO
**^" N^f "*^r '*^i **^^ "^r *NJ *>j
*"^r s"^j *sT ^T >^' ^^ **^* ^J*
CO i— CM
LO f~^ C^ £""i —
** I ^^ \^^ \^^ t "•
o o o o o
o o o o o
V V V \S V
CO T— CM
m o o o T—
o o o o o
o o o o o
V V \/ V V
i^T ""^* ^^ ^"^ >i^r
*^j **T "*^r **^ ^^T
^ C
as cd
PM 4J
3
r-l
I—I
o
&4
CO
4J
C
4J
rj
rH
r-l
o
CL,
CJ
•r-l
X
o
r-l
r*^
C
o
e
•H
4-)
C
•
T—
o
•r-l
C
r-l
• r-l
CO
vO
CM
a
•H
r-l
r-l
cd
43
4-1
r>!
CM
CJ
S3
•rl
N
oo
CM
72
-------
4J
c
o
u
42
H
i-J
OH
CO
>t
S 05
HH
US
CQ
CO H M
< H
*3-
CO H
CO
m
s/
m
T-O
O> CM
m CM
o o
O r-
o o
• •
o o
o
o
•
o
\/
v
t- O
• •
T- O
CM
T- O
000
OO
O
s/
O
v
CO
o
as
OT
4J
c
4-1
a3
4J
3
o
Oi
o
04
ctf
c
o
-------
x-^
-o
cu
^
d
-r4
d
O
u
x^
m
^-»
1
>
•<
f^
8*
Cx] U
H H
33 as
CO H W
>< ca
d
cu
>
cu
CO
B 0
cu
CO
cd
cu
oo
o
CO
cu
•o
cu
a
CO
3
CO
4-)
TD
d
CU
•a
o
u
cu
CU
t-H
a
o
4->
CO
74
-------
Hg Raw
Material
To Tailings
To Tailings
To Tailings
To Tailings
To Tailings
Mercury Product
" * To Tailings
Figure V-1
SAMPLE LOCATIONS AT PRIMARY PRECIOUS
METALS AND MERCURY PLANT A
75
-------
76
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Section V of this supplement presented data from primary precious
metals and mercury plant sampling visits and subsequent chemical
analyses. The analytical data from one primary precious metals
plant was not presented in Section V because it was claimed to be
confidential. This section examines both the confidential and
nonconfidential data and discusses the selection or exclusion of
pollutants for potential limitation. The legal basis for the
exclusion of toxic pollutants under Paragraph 8(a) of the
Settlement Agreement is presented in Section VI of the General
Development Document.
Each pollutant selected for potential limitation is discussed in
Section VI of the General Development Document. That discussion
provides information concerning the nature of the pollutant
(i.e., whether it is a naturally occurring substance, processed
metal, or a manufactured compound); general physical properties
and the form of the pollutant; toxic effects of the pollutant in
humans and other animals; and behavior of the pollutant in POTW
at the concentrations expected in industrial discharges.
The discussion that follows describes the analysis that was per-
formed to select or exclude toxic pollutants for further consid-
eration for limitations and standards. Also, it describes the
analysis that was performed to select or exclude conventional
pollutants for limitation. Toxic pollutants will be considered
for limitation if they are present in concentrations treatable by
the technologies considered in this analysis. The treatable
concentrations used for the toxic metals were the long-term
performance values achievable by chemical precipitation, sedimen-
tation, and filtration. The treatable concentrations used for
the toxic organics were the long-term performance values achiev-
able by carbon adsorption (see Section VII of the General
Development Document Combined Metals Data Base).
CONVENTIONAL POLLUTANT PARAMETERS
This study examined samples from the primary precious metals and
mercury subcategory for three conventional pollutant parameters
(oil and grease, total suspended solids, and pH).
CONVENTIONAL POLLUTANT PARAMETERS SELECTED
The conventional pollutants or pollutant parameters selected for
limitation in this subcategory are:
77
-------
oil and grease
total suspended solids (TSS)
PH
Oil and grease was detected in two of 10 samples at concentra-
tions above the treatability concentration of 10.0 mg/1. The
measured concentrations were 60 and 170 mg/1. These high concen-
trations occurred in the combined raw wastewater stream from the
smelter and electrolytic cells wet air pollution control and in
the silver chloride reduction spent solution. Therefore, oil and
grease is selected for limitation in this subcategory.
TSS was detected at concentrations above the treatability concen-
tration of 2.6 mg/1 in eight of the 10 raw waste samples analyzed
for this study. These eight TSS concentration values ranged from
4 to 3,700 mg/1. Furthermore, most of the specific methods used
to remove toxic metals do so by converting these metals to pre-
cipitates, and these toxic-metal-containing precipitates should
not be discharged. Meeting a limitation on total suspended
solids helps ensure that removal of these precipitated toxic
metals has been effective. For these reasons, total suspended
solids are selected for limitation in this subcategory.
The nine pH values observed during this study ranged from 0.9 to
8.4. Six of the nine values were equal to or less than 2.6, one
value was 6.8 and the other two fell within the 7.5 to 10.0 range
considered desirable for discharge to receiving waters. Many
deleterious effects are caused by extreme pH values or rapid
changes in pH. Also, effective removal of toxic metals by
precipitation requires careful control of pH. Since pH control
within the desirable limits is readily attainable by available
treatment, pH is selected for limitation in this subcategory.
TOXIC POLLUTANTS
The frequency of occurrence of the toxic pollutants in the raw
wastewater samples taken is presented in Table VI-1. Table VI-1
is based on the raw wastewater data presented in Section V (see
Tables V-12 through V-15) as well as the primary precious metals
analytical data being held confidential. These data provide the
basis for the categorization of specific pollutants, as discussed
below.
TOXIC POLLUTANTS NEVER DETECTED
The toxic pollutants listed below were not detected in any raw
wastewater samples from this subcategory; therefore, they are not
selected for consideration in establishing limitations:
1. acenaphthene
2. acrolein
3. acrylonitrile
78
-------
5. benzidine
6. carbon tetrachloride
7. chlorobenzene
8. 1,2,4-trichlorobenzene
9. hexachlorobenzene
10. 1,2-dichloroethane
11. 1,1,1-trichloroethane
12. hexachloroethane
13. 1,1-dichloroethane
14. 1,1,2-trichloroethane
15. 1,1,2,2-tetrachloroethane
16. chloroethane
17. bis(2-chloromethyl) ether (deleted)
18. bis(2-chloroethyl) ether
19. 2-chloroethyl vinyl ether
20. 2-chloronaphthalene
21. 2,4,6-trichlorophenol
22. parachlorometa cresol
23. chloroform
24. 2-chlorophenol
25. 1,2-dichlorobenzene
26. 1 ,3-dichlorobenzene
27. 1,4-dichlorobenzene
28. 3,3'-dichlorobenzidine
29. 1,1-dichloroethylene
30. 1,2-trans-dichloroethylene
31. 2,4-dichlorophenol
32. 1,2-dichloropropane
33. 1,3-dichloropropylene
34. 2,4-dimethylphenol
35. 2,4-dinitrotoluene
36. 2,6-dinitrotoluene
37. 1 ,2-diphenylhydrazine
38. ethylbenzene
39. fluoranthene
40. 4-chlorophenyl phenyl ether
41. 4-bromophenyl phenyl ether
42. bis(2-chloroisopropyl)ether
43. bis(2-chloroethoxy)methane
45. methyl chloride (chloromethane)
46. methyl bromide (bromomethane)
47. bromoform
48. dichlorobromomethane
49. trichlorofluoromethane (deleted)
50. dichlorodifluoromethane (deleted)
51. chlorodibromomethane
52. hexachlorobutadiene
53. hexachlorocyclopentadiene
54. isophorone
55. naphthalene
56. nitrobenzene
79
-------
57. 2-nitrophenol
58. 4-nitrophenol
59. 2,4-dinitrophenol
60. 4,6-dinitro-o-cresol
61. N-nitrosodimethylamine
62. N-nitrosodiphenylamine
63. N-nitrosodi-n-propylamine
64. pentachlorophenol
67. butyl benzyl phthalate
69. di-n-octyl phthalate
71. dimethyl phthalate
72. benzo(a)anthracene
73. benzo(a)pyrene
'74. 3,4-benzofluoranthene
75. benzo(k)fluoranthene
76. chrysene
77. acenaphthylene
79. benzo(ghi)perylene
80. fluorene
82. dibenzo(a,h)anthracene
83. indeno (1,2,3-cd)pyrene
84. pyrene
85. tetrachloroethylene
87. trichloroethylene
88. vinyl chloride
89. aldrin
90. dieldrin
91. chlordane
92. 4,4'-DDT
93. 4,4'-DDE
94. 4,4'-DDD
95. alpha-endosulfan
96. beta-endosulfan
97. endosulfan sulfate
98. endrin
99. endrin aldehyde
100. heptachlor
101. heptachlor epoxide
102. alpha-BHC
103. beta-BHC
104. gamma-BHC
105. delta-BHC
106. PCB-1242 (a)
107. PCB-1254 (a)
108. PCB-1221 (a)
109. PCB--.232 (b)
110. PCB-1248 (b)
111. PCB-1260 (b)
112. PCB-1016 (b)
113. toxaphene
80
-------
116. asbestos
129. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
(a),(b) Reported together.
TOXIC POLLUTANTS NEVER FOUND ABOVE THEIR ANALYTICAL QUANTIFICA-
TION CONCENTRATION
The toxic pollutants listed below were never found above their
analytical quantification concentration in any raw wastewater
samples from this subcategory; therefore, they are not selected
for consideration in establishing limitations.
65. phenol
66. bis(2-ethylhexyl) phthalate
68. di-n-butyl phthalate
78. anthracene (a)
81. phenanthrene (a)
114. antimony
(a) Reported together.
TOXIC POLLUTANTS PRESENT BELOW CONCENTRATIONS ACHIEVABLE BY
TREATMENT
The pollutants listed below are not selected for consideration in
establishing limitations because they were not found in any raw
wastewater samples from this subcategory above concentrations
considered achievable by existing or available treatment tech-
nologies. These pollutants are discussed individually following
the list.
117. beryllium
125. selenium
Beryllium was detected at a concentration of 0.15 mg/1 in one of
the 10 samples analyzed. Available treatment methods can reduce
beryllium concentrations only to 0.2 mg/1 and this pollutant is,
therefore, not considered for limitation.
Selenium was detected in two of 10 samples at concentrations
ranging from 0.044 to 0.063 mg/1. These concentrations are below
the minimum selenium concentration of 0. 2 mg/1 achievable by
available treatment methods. Additionally, these concentrations
of selenium may be attributable to its presence in the source
water at a concentration of 0.10 mg/1. Selenium, therefore, is
not considered for limitation.
81
-------
TOXIC POLLUTANTS DETECTED IN A SMALL NUMBER OF SOURCES
The following pollutants were not selected for limitation because
they are detectable in the effluent from only a small number of
sources within the subcategory and they are uniquely related to
only those sources.
4. benzene
44. methylene chloride
70. diethyl phthalate
86. toluene
121. cyanide
Although these pollutants were not selected for limitation in es-
tablishing nationwide regulations, it may be appropriate, on a
case-by-case basis, for the local permitter to specify effluent
limitations.
Benzene was detected above its treatable concentration of 0.01
mg/1 in one of three samples analyzed at a concentration of 0.016
mg/1. This pollutant is not attributable to specific materials
or processes asociated with the primary precious metals and
mercury subcategory, and is not expected to be present in the
wastewater. For this reason, and because very little removal of
benzene can be expected with treatment, this pollutant is not
considered for limitation.
Methylene chloride was detected above its treatability concentra-
tion of 0.01 mg/1 at concentrations ranging from 0.036 to 0.046
mg/1 in all three samples analyzed. This pollutant is not
attributable to specific materials or processes associated with
the primary precious metals and mercury subcategory, but is a
common solvent used in analytical laboratories. Because methyl-
ene chloride is not expected to be present in the wastewater, as
well as the high probability of sample contamination, this
pollutant is not considered for limitation.
Diethyl phthalate was detected above its treatable concentration
of 0.01 mg/1 in one of three samples analyzed at a concentration
of 0.016 mg/1. This pollutant is not attributable to specific
materials or processes associated with the primary precious
metals and mercury subcategory, and is not expected to be present
in the wastewater. For this reason, and because very little
removal of diethyl phthalate can be expected with treatment, this
pollutant is not considered for limitation.
Toluene was detected above its treatable concentration of 0.01
mg/1 in two of three samples analyzed at concentrations of 0.023
and 0.05 mg/1. This pollutant is not attributable to specific
materials or processes associated with the primary precious
82
-------
metals and mercury subcategory, and is not expected to be present
in the wastewater. For this reason, and because very little
removal of toluene can be expected with treatment, this pollutant
is not considered for limitation.
Cyanide was measured at concentrations ranging from 0.049 to 0.2
mg/1 in three of the four samples for which it was analyzed.
These concentrations are above the treatability concentration of
0.047 mg/1, but are suspected to be present because of source
water contamination. The source water was found to contain
cyanide at a concentration of 8.6 mg/1. Because of its presence
in the source water at a high concentration, cyanide is not
considered for limitation.
TOXIC POLLUTANTS SELECTED FOR FURTHER CONSIDERATION IN ESTAB-
LISHING LIMITATIONS AND STANDARDS
The toxic pollutants listed below are selected for further con-
sideration in establishing limitations and standards for this
subcategory. The toxic pollutants selected for further consider-
ation for limitation are each discussed following the list.
115. arsenic
118. cadmium
11 9. chromium
120. copper
122. lead
123. mercury
124. nickel
126. silver
127. thallium
128. zinc
Arsenic was detected in two of 10 samples at concentrations of
0.6 and 17 mg/1. The concentration achievable by treatment
methods is 0.34 mg/1. These concentrations were detected in
silver chloride reduction spent solution and calcine quench
water. Arsenic was detected, but at levels below treatability,
in the other eight samples. Therefore, arsenic is selected for
further consideration for limitation.
Cadmium was detected above its treatable concentration (0.049
mg/1) in two of 10 raw wastewater samples analyzed. The treat-
able concentrations were detected in silver chloride reduction
spent solution and calcine quench water. Therefore, cadmium is
selected for further consideration for limitation.
Chromium was detected above its treatable concentration of 0.07
mg/1 in silver chloride reduction spent solution and calcine
quench water. The highest concentration was 25 mg/1. All eight
33
-------
other samples indicated that chromium was present, but at a
concentration below treatability. Therefore, chromium is
selected for further consideration for limitation.
Copper was measured in two samples at concentrations above the
treatable concentration of 0.39 mg/1. Copper was also detected
in the remaining eight samples, but at concentrations below that
achievable by treatment. The highest concentration of copper
found was 23,000 mg/1. Therefore, copper is selected for further
consideration for limitation.
Lead was detected in six raw waste streams at concentrations
above the 0.08 mg/1 attainable by identified treatment technol-
ogy. These concentrations ranged from 0.1 to 600 mg/1. For this
reason, lead is selected for further consideration for limita-
tion.
Mercury was detected in six of the 10 samples analyzed at concen-
trations ranging from 0.84 to 360 mg/1. These concentrations are
well above the concentration of 0.036 achievable by current
treatment methods. In addition, mercury was detected in the
remaining four samples, but at values below the treatable concen-
tration. For these reasons, mercury is selected for further
consideration for limitation.
Nickel was detected in the silver chloride reduction spent solu-
tion at a concentration of 29 mg/1. The treatable concentration
for nickel is 0.22 mg/1. Nickel was detected, but below treata-
ble concentrations in all nine of the other samples. Therefore,
nickel is selected for further consideration for limitation.
Silver was detected in two samples at concentrations of 0.13 and
6.1 mg/1. These concentrations are above silver's treatable
concentration of 0.07 mg/1. Silver is, therefore, selected for
further consideration for limitation.
Thallium was detected above its treatable concentration (0.34
mg/1) in two of 10 samples analyzed. The quantifiable concentra-
tions ranged from 0.12 to 2.6 mg/1. Since thallium was present
in concentrations exceeding the concentration achievable by iden-
tified treatment technology, it is selected for consideration for
limitation.
Zinc was detected above its treatable concentration (0.23 mg/1)
in three of 10 samples analyzed. The quantifiable concentrations
ranged from 0.10 to 15.0 mg/1. Since zinc was present in concen-
trations exceeding the concentration achievable by identified
treatment technology, it is selected for consideration for
limitation.
84
-------
V
&
rt
H
co o
H O
Z W
< H
H <
» CJ
n4 pq
O CO
PL,
O 06
>< 8
O P^ Di
H W W
b <3
°sg
5j My
U CO
Z CO <
W >4S
CJ
O CO
§2
CJ
>• w
CJ pi
23 A-i
w
w
f6
CU
•o
11
4J
o
S
&
3
1
0)
1— 1
_o
•§
*
£
•a
_o
y
<«
^
1
u
S
£
a;
S
,
1
1
1
0)
CO
"8
S
4J
£
MJ
O
14
0)
«J
O
VJ
•fl
1
|
2
c
1
g
1
4-4
-U
I
Jl
O 4J
<8
01 U
—1 U
Xl
tS
f
ll
4) i-*
r- 1 U
IB
J-l-3
S^
^ M
U-J U
4J (p
S CJ
5-8
§
S'S
Js
87
§ N
OJ >•
U— 1
4J CD
W_g
eS
15
1
!~
^3
JJ^M
§ bf
O E
Pollutant
cs
^^ CO CO CO CO CO CO CO CO CO CO CO CO CO CO
oooooooooooooooo
oooooooooooooooo
oo oooooooooooooo
oooooooooooooooo
c
Q) Jt
j_j 3^4iS S*^®
I— H O^JioC-COjC
J3 SjNWWiCOAJUtJ
0) O OJ O C OJ O J3 0* O nJ
0) !— 1 ctfCi— I4>O«— (UO^-li-ia)
C *^ 1^ ^ Fl ^J ^4 JM ^ V >C W C
S^^ f^ S *^ o ^ -«^ ^5 ^3 T«" "o ^3 c^ c^ Vj
O ^i N M ^ O *(0l »cO I * *O
« ™ »J^j S-g-x-V^ --V-6
^CMCO^UOvCI^OOOvO-OlCO^-^vD
CO CO CO CO
coco coco
OO 00
o o o o
00 OO
o o o o
VJ
Vd 01
pi
tl 4;
*4
•o
1
CO
—
CM
COCO
00
00
OO
00
chlorobenzene
ichlorobenzidine
-rf*O
T> 1
-*CO
•—CO
CM CM
CO CO
00
0 0
0 O
00
HI
S
chloroethylene
ans -d Ichloroethy 1
i-« w
7V
r-CM
— —
CM CO
COCO
CO CO
00
00
OO
00
chlorophenol
chloropropane
f4 >~J
•o-o
1 1
-*CM
CM-
CO CO
COCO
CO CO
00
00
OO
00
chloropropylene
methylphenol
•H .^
77
co
-------
•o g) QJ
a di o c
•u ij c o
S5H83
S I «&•
Q -3 —I 4J
as
JJg
•o*
OJ
r- 1
,O
cO
H
>*
PS
CO O
H 0
S3 W
3 %
H <
3 CJ
i-J «
hJ ^ZD
O CO
CM
CJ PS
HH ^~>
X CJ
O PS PS
S H
fa • W
CJ Qi
a PM
4) U-.5
co a u
O tS
|W1
(1) W X-,
--< I- ^5
i gJX
te o u^ —
u 5 1
£ S -5
-I- S
S4J -rf^
•^ og-
±>S §8
— CO CM
•
CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CN CO »—
CO CO CO CO CO CO fO COcOfl COCOCOCOCOCOCOCOCOCOCO
«
CMc>)CSJcMCNlcvlCNJcMCNCM^CVlCNlcMCMCMCMcM
-------
OCM O CM CMCM COvO vO — O CM
4J C
"S 5 0
prf
CO O
H O
S W
< H
H <
3 CJ
I-J PQ
co en co co co ro co co co
co co co co co
C
•H
4-)
C
o
CJ
0)
cO
H
cj pc!
1-4 3
x u
O pi pi
H W W
S H
EH <:
O Q^
a w
w < H
O CO
W rJ.5
05 * W
cj p-j
55 PM
» SM
CXpi
W Si 8*>>S iu-
BJ ^i o ti o J/i-t E
6$
87
-------
I I
•u e
to 0)
•o a u c
Sgg.5
O O u
Sgc.2
JJ O —I JJ
a!$
o
3
TJ nj
35 01
nj O
8'
a; 5
a -3
5 a)
CD o
x! to
o o
llg
/— \
T3
(U
3
C
•H
4J
C
o
u
N^X
M
>
0)
rH
43
^2
1C POLLUTANTS
URY SUBCATEGORY
:>er of Detected be
nples Quantlficat
Lyzed NO Concentratil
sy. i^s
»O -* »CM
OO 00
,^\
o as 3 S "
H W 2S g
S w .2
to H ^
o Q <; o »TJ
2 "S U § N
w~s
M j < 2
-.> _j t-^, 4J
05 <; ^5 oi
oShJ -3
» W2 ,
O S <3 5
O O O fj "^
"8
r ^ -u
sj H ^
>• W
O as c
^ ^5g
[ij is u ^i /^
"D Sj o (8 4J ta
*"Z?j ^^ "^ O TO *^" *
%% was-
Cl4 <1 r-l -^ C
3j g n) u ai M
to I— I •§ S B •-•
as 3-8
1
o o ^
O lA
^-000 C
d d .n ^ .3
jj
trj
S
JJ
1
|
g
f~* -r4
fjy 4j
JO f-J
JJ
tS
u
O
g
Q
J3
1
&
s~^
-D
*^s
U
1
cu
BO
S
U
u
8.
s
3
'-H
O
CO
•rH
00
X
— 1
3
M-t
n
8
p
£
GO
U
1!
•8
•H
C
§
£
_^
«
JJ
5
t>T
lA
m
tn
•n
1
Jl
2
£
w
£
4-(
1
U
03
i!
i
1
§
T-»
u
S
.,4
UJ
•H
u
S
O"
-4 3>
« r-
o
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION VII
CONTROL AND TREATMENT TECHNOLOGIES
The preceding sections of this supplement discussed the sources,
flows, and characteristics of the wastewaters from primary pre-
cious metals and mercury plants. This section summarizes the
description of these wastewaters and indicates the treatment
technologies which are currently practiced in the primary
precious metals and mercury subcategory for each waste stream.
Secondly, this section presents the control and treatment tech-
nology options which were examined by the Agency for possible
application to the primary precious metals and mercury
subcategory.
CURRENT CONTROL AND TREATMENT PRACTICES
Control and treatment technologies are discussed in general in
Section VII of the General Development Document. The basic prin-
ciples of these technologies and the applicability to wastewater
similar to that found in this subcategory are presented there.
This section presents a summary of the control and treatment
technologies that are currently being applied to each of the
sources generating wastewater in this subcategory. As discussed
in Section V, wastewater associated with the primary precious
metals and mercury subcategory is characterized by the presence
of the toxic metal pollutants, suspended solids, and oil and
grease. This analysis is supported by the raw (untreated)
wastewater data presented for specific sources. Construction of
one wastewater treatment system for combined treatment allows
plants to take advantage of economic scale and in some instances
to combine streams of different alkalinity to reduce treatment
chemical requirements.
All but one of the plants within this subcategory have a zero
discharge status. The one discharging facility discharges to a
surface water from a tailings pond. Zero discharge is achieved
in most plants through a combination treatment system consisting
of a tailings pond and recycle or reuse. One of the three plants
with a smelter scrubber achieves zero discharge of that waste
stream by 100 percent recycle. Partial recycle is used only on
two waste streams, the smelter scrubber and the calciner scrubber
wastewater. Table VII-1 presents a summary of the number of
plants with each waste stream and the treatment technologies
currently in place.
89
-------
CONTROL AND TREATMENT OPTIONS
The Agency examined three control and treatment technology
options that are applicable to the primary precious metals and
mercury subcategory. The options selected for evaluation
represent a combination of in-process flow reduction, preliminary
treatment technologies applicable to individual waste streams,
and end-of-pipe treatment technologies.
OPTION A
Option A for the primary precious metals and mercury subcategory
requires control and treatment technologies to reduce the
discharge of wastewater volume and pollutant mass.
The Option A treatment scheme consists of chemical precipitation
and sedimentation technology. Specifically, lime or some other
alkaline compound is used to precipitate toxic metal ions as
metal hydroxides. The metal hydroxides and suspended solids
settle out and the sludge is collected. Vacuum filtration is
used to dewater sludge.
Preliminary treatment consisting of oil skimming to remove oil
and grease is also included in Option A.
OPTION B
Option B for the primary precious metals and mercury subcategory
consists of the Option A (oil skimming, chemical precipitation
and sedimentation) treatment scheme plus flow reduction tech-
niques to reduce the discharge of wastewater volume. In-process
changes which allow for recycle of smelter, electrolytic cells,
and calciner scrubber water are the principal control mechanisms
for flow reduction.
OPTION C
Option C for the primary precious metals and mercury subcategory
consists of all control and treatment requirements of Option B
(in-process flow reduction, oil skimming, chemical precipitation
and sedimentation) plus multimedia filtration technology added at
the end of the Option B treatment scheme. Multimedia filtration
is used to remove suspended solids, including precipitates of
metals, beyond the concentration attainable by gravity sedimen-
tation. The filter suggested is of the gravity, mixed-media
type, although other forms of filters, such as rapid sand filters
or pressure filters would perform satisfactorily. The addition
of filters also provides consistent removal during periods of
time in which there are rapid increases in flows or loadings of
pollutants to the treatment system.
90
-------
co
co
43 CO
M-l 4-> C4
O-H
J-l O
CO CO
43 4-> CO
B C <-l
3 CO O
25 rH >J
OH O
CO
25
O i- r- r- ,- ,-
4-1 4J O 4J
O -H OH C
CO
J-l
CO
_Q
a
co a
co
'g
CO
£
a
fj Co
14-1 4J CO
OjH r-l
rH CO
43 4-) CO
B C 4->
3 cO co
23 rH CO
OH :s
CO t— i—
Waste Stream
rH
O
S-i
c
o
o
c
o
•H
4J
rH
rH
o
ex
•H
cO
4_)
CO
3
V-j
CO
4J
rH
CO
a
CO
ide reduction spent solution
M
O
rH
43
CJ
J_l
co
^
rH
•H
CO
§
•1-1
4J
rH
rH
O
cx
J-l
•H
cO
4J
co
CO
rH
rH
CO
O
o
•rH
4J
>%
rH
O
Jj
4J
O
CO
rH
III
rH
O
J-l
4->
C
o
CJ
preparation wet air pollu-
ol
i_i
CO 4-)
4J g
^ O
rH 0
0
W f^
4J 0
O M-l
CO 4->
rH
III
CO
4-)
CO
CO
CO
to
rH
CO
4J
CO
>-,
J-l
O
J_l
co
^
rH
•H
CO
CO
CO
• c
•H
rH
V-l
CO
CO
T>
c
cO
CO
cO
•H
0
cO
CO
co
S
•H
rH
CO
*O
rH
Q
05
air pollution control
4J
CO
[5
rH
CO
C
•H
O
rH
cO
U
ch water
c
co
rj
cr
CO
c
•H
O
rH
CO
C_3
ck gas contact cooling water
cO
4J
CO
^j
CO
c
•r-l
O
rH
CO
owdown
rH
43
In
CO
CO
C
co
c
o
U
rH
CO
4->
cO
43
CO
43
00
C
•H
C
cO
CO
rH
0
^
VH
rj
O
CO
23
91
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION VIII
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS
This section presents a summary of compliance costs for the
primary precious metals and mercury subcategory and a description
of the treatment options and subcategory-specific assumptions
used to develop these estimates. Together with the estimated
pollutant reduction performance presented in Sections IX, X, XI,
and XII of this supplement, these cost etimates provide a basis
for evaluating each regulatory option. These cost estimates are
also used in determining the probable economic impact of regula-
tion on the subcategory at different pollutant discharge levels.
In addition, this section addresses nonwater quality environ-
mental impacts of wastewater treatment and control alternatives,
including air pollution, solid wastes, and energy requirements,
which are specific to the primary precious metals and mercury
subcategory.
TREATMENT OPTIONS FOR EXISTING SOURCES
As discussed in Section VII, three treatment options have been
developed for existing primary precious metals and mercury
sources. The options are summarized below and schematically
presented in Figures X-1 through X-3.
OPTION A
Option A consists of preliminary treatment using oil/water-
separation where required and chemical precipitation and sedimen-
tation end-of-pipe technology.
OPTION B
Option B consists of in-process flow reduction and oil/water
separation preliminary treatment where required, and end-of-pipe
technology consisting of chemical precipitation and sedimenta-
tion. The in-process flow reduction measure consists of the
recycle of smelter scrubber water, electrolytic cells scrubber
water, and calciner scrubber water through holding tanks.
OPTION C
Option C requires the in-process flow reduction and oil/water
separation preliminary treatment measures of Option B, and end-
of-pipe treatment technology consisting of chemical precipita-
tion, sedimentation, and multimedia filtration.
93
-------
COST METHODOLOGY
A detailed discussion of the methodology used to develop the com-
pliance costs is presented in Section VIII of the General Devel-
opment Document. Plant-by-plant compliance costs have been
estimated for the nonferrous metals manufacturing category and
are presented in the administrative record supporting this regu-
lation. The costs developed for the proposed regulation are pre-
sented in Table VIII-1 for the direct dischargers.
Each of the general assumptions used to develop compliance costs
is presented in Section VIII of the General Development Document.
No subcategory-specific assumptions were used in developing
compliance costs for the primary precious metals and mercury
subcategory.
NONWATER QUALITY ASPECTS
A general discussion of the nonwater quality aspects of the con-
trol and treatment options considered for the nonferrous metals
category is contained in Section VIII of the General Development
Document. Nonwater quality impacts specific to the primary pre-
cious metals and mercury subcategory, including energy require-
ments, solid waste and air pollution, are discussed below.
ENERGY REQUIREMENTS
The methodology used for determining the energy requirements for
the various options is discussed in Section VIII of the General
Development Document. Energy requirements for the three options
considered are estimated at 4,224 kWh/yr, 4,224 kWh/yr, and 5,155
kWh/yr for Options A, B, and C, respectively. Option B energy
requirements are the same as those for Option A because the one
discharging plant has no flow reduction. Option C, which
includes filtration, increases energy consumption over Option B
by approximately 18 percent. Option C represents roughly 1
percent of a typical plant's electrical energy usage. It is
therefore concluded that the energy requirements of the treatment
options considered will have no significant impact on total plant
energy consumption.
SOLID WASTE
Sludge generated in the primary precious metals and mercury
subcategory is due to oily wastes from oil/water separation and
the precipitation of meual hydroxides and carbonates using lime.
Sludges associated with the primary precious metals and mercury
subcategory will necessarily contain quantities of toxic metal
pollutants. These sludges are not subject to regulation as
hazardous wastes since wastes generated by primary smelters and
94
-------
refiners are currently exempt from regulation by Act of Congress
(Resource Conservation and Recovery Act (RCRA), Section 3001(b) ) ,
as interpreted by EPA. If a small excess of lime is added during
treatment, the Agency does not believe these sludges would be
identified as hazardous under RCRA in any case. (Compliance
costs include this amount of lime.) This judgment is based on
the results of Extraction Procedure (EP) toxicity tests performed
on similar sludges (toxic metal-bearing sludges) generated by
other industries such as the iron and steel industry. A small
amount of excess lime was added during treatment, and the sludges
subsequently generated passed the toxicity test. See CFR
§261.24. Thus, the Agency believes that the wastewater sludges
will similarly not be EP toxic if the recommended technology is
applied.
Although it is the Agency's view that solid wastes generated as a
result of these guidelines are not expected to be hazardous,
generators of these wastes must test the waste to determine if
the wastes meet any of the characteristics of hazardous waste
(see 40 CFR 262.11).
If these wastes should be identified or are listed as hazardous,
they will come within the scope of RCRA's "cradle to grave"
hazardous waste management program, requiring regulation from the
point of generation to point of final disposition. EPA's gener-
ator standards would require generators of hazardous nonferrous
metals manufacturing wastes to meet containerization, labeling,
recordkeeping, and reporting requirements; if plants dispose of
hazardous wastes off-site, they would have to prepare a manifest
which would track the movement of the wastes from the generator's
premises to a permitted off-site treatment, storage, or disposal
facility. See 40 CFR 262.20 45 FR 33142 (May 19, 1980), as
amended at 45 FR 86973 (December 31, 1980). The transporter
regulations require transporters of hazardous wastes to comply
with the manifest system to assure that the wastes are delivered
to a permitted facility. See 40 CFR 263.20 45 FR 33151 (May 19,
1980), as amended at 45 FR 86973 (December 31, 1980). Finally,
RCRA regulations establish standards for hazardous waste treat-
ment, storage, and disposal facilities allowed to receive such
wastes. See 40 CFR Part 464 46 FR 2802 (January 12, 1981), 47 FR
32274 (July 26, 1982).
Even if these wastes are not identified as hazardous, they still
must be disposed of in compliance with the Subtitle D open dump-
ing standards, implementing 4004 of RCRA. See 44 FR 53438
(September 13, 1979). The Agency has calculated as part of the
costs for wastewater treatment the cost of hauling and disposing
of these wastes. For more details, see Section VIII of the
General Development Document.
95
-------
Sludge generation for BPT of the primary precious metals and
mercury subcategory is estimated at 11.355 metric tons per year.
Sludge generation for BAT is not expected to be significantly
different.
AIR POLLUTION
There is no reason to believe that any substantial air pollution
problems will result from implementation of oil/water separation,
chemical precipitation, sedimentation, and multimedia filtration.
These technologies transfer pollutants to solid waste and are not
likely to transfer pollutants to air.
96
-------
Table VIII-1
COST OF COMPLIANCE FOR THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
DIRECT DISCHARGERS
(March, 1982 Dollars)
Total Required Total
Option Capital Cost Annual Cost
A 27,500 9,000
B 27,500 9,000
C 30,000 10,000
97
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
This section defines the effluent characteristics attainable
through the application of best practicable control technology
currently available (BPT), Section 301 (b) (a) (A) . BPT reflects
the existing performance by plants of various sizes, ages, and
manufacturing processes within the primary precious metals and
mercury subcategory, as well as the established performance of
the recommended BPT systems. Particular consideration is given
to the treatment already in place at plants within the data base.
The factors considered in identifying BPT include the total cost
of applying the technology in relation to the effluent reduction
benefits from such application, the age of equipment and facili-
ties involved, the manufacturing processes employed, nonwater
quality environmental impacts (including energy requirements),
and other factors the Administrator considers appropriate. In
general, the BPT level represents the average of the existing
performances of plants of various ages, sizes, processes, or
other common characteristics. Where existing performance is
uniformly inadequate, BPT may be transferred from a different
subcategory or category. Limitations based on transfer of
technology are supported by a rationale concluding that the
technology is, indeed, transferable, and a reasonable prediction
that it will be capable of achieving the prescribed effluent
limits (see Tanner's Council of America v. Train, 540 F.2d 1188
(4th Cir. 1176).BPT focuses on end-o±-pipe treatment rather
than process changes or internal controls, except where such
practices are common within the subcategory.
TECHNICAL APPROACH TO BPT
The Agency studied the nonferrous metals category to identify the
processes used, the wastewaters generated, and the treatment pro-
cesses installed. Information was collected from the category
using data collection portfolios, and specific plants were sam-
pled and the wastewaters analyzed. In making technical assess-
ments of data, reviewing manufacturing processes, and assessing
wastewater treatment technology options, both indirect and direct
dischargers have been considered as a single group. An examina-
tion of plants and processes did not indicate any process differ-
ences based on the type of discharge, whether it be direct or
indirect.
99
-------
As explained in Section IV, the primary precious metals and mer-
cury subcategory has been subdivided into 11 potential wastewater
sources. Since the water use, discharge rates, and pollutant
characteristics of each of these wastewaters is potentially
unique, effluent limitations will be developed for each of the 11
subdivisions.
For each of the subdivisions, a specific approach was followed
for the development of BPT mass limitations. The first require-
ment to develop these limititations is to account for production
and flow variability from plant to plant. Therefore, a unit of
production or production normalizing parameter (PNP) was deter-
mined for each waste stream which could then be related to the
flow from the process to determine a production normalized flow.
Selection of the PNP.for each process element is discussed in
Section IV. Each process within the subcategory was then ana-
lyzed to determine (1) which subdivisions were present, (2) the
specific flow rates generated for each subdivision, and (3) the
specific production normalized flows for each subdivision. This
analysis is discussed in detail in Section V. Nonprocess waste-
waters such as rainfall runoff and noncontact cooling water are
not considered in the analysis.
Production normalized flows for each subdivision were then ana-
lyzed to determine the flow to be used as part of the basis for
BPT mass limitations. The selected flow (sometimes referred to
as a BPT regulatory flow or BPT discharge rate) reflects the
water use controls which are common practices within the cate-
gory. The BPT regulatory flow is based on the average of all
applicable data. Plants with normalized flows above the average
may have to implement some method of flow reduction to achieve
the BPT limitations.
The second requirement to calculate mass limitations is the set
of concentrations that are achievable by application of the BPT
level of treatment technology. Section VII discusses the various
control and treatment technologies which are currently in place
for each wastewater source. In most cases, the current control
and treatment technologies consist of a combination of tailings
ponds and reuse and recycle of process water. Chemical precipi-
tation .and sedimentation technology and performance is trans-
ferred to this subcategory, because current treatment is
inadequate. Oil skimming is applied to streams with treatable
concentrations of oil and grease.
Using these regulatory flows and the achievable concentrations,
the next step is to calculate mass loadings for each wastewater
source or subdivision. This calculation was made on a stream-by-
stream basis, primarily because plants in this subcategory may
perform one or more of the operations in various combinations.
100
-------
The mass loadings (milligrams of pollutant per troy ounce or
metric ton of production - mg/T.O. or mg/kkg) were calculated by
multiplying the BPT regulatory flow (1/T.O. or 1/kkg) by the con-
centration achievable by the BPT level of treatment technology
(mg/1) for each pollutant parameter to be limited under BPT.
These mass loadings are published in the Federal Register and in
CFR Part 400 as the effluent limitations guidelines.
The mass loadings which are allowed under BPT for each plant will
be the sum of the individual mass loadings for the various waste-
water sources which are found at particular plants. Accordingly,
all the wastewater generated within a plant may be combined for
treatment in a single or common treatment system, but the efflu-
ent limitations for these combined wastewaters are based on the
various wastewater sources which actually contribute to the com-
bined flow. This method accounts for the variety of combinations
of wastewater sources and production processes which may be found
at primary precious metals and mercury plants.
The Agency usually establishes wastewater limitations in terms of
mass rather than concentration. This approach prevents the use
of dilution as a treatment method (except for controlling pH).
The production normalized wastewater flow (1/T.O. or 1/kkg) is a
link between the production operations and the effluent limita-
tions. The pollutant discharge attributable to each operation
can be calculated from the normalized flow and effluent concen-
tration achievable by the treatment technology and summed to
derive an appropriate limitation for each plant.
INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES
In balancing costs in relation to pollutant removal estimates,
EPA considers the volume and nature of existing discharges, the
volume and nature of discharges expected after application of
BPT, the general environmental effects of the pollutants, and the
cost and economic impacts of the required pollution control
level. The Act does not require or permit consideration of water
quality problems attributable to particular point sources or
industries, or water quality improvements in particular water
quality bodies. Accordingly, water quality considerations were
not the basis for selecting the proposed BPT. See Weyerhaeuser
Company v. Costle, 590 F.2d 1011 (D.C. Cir. 1978).
The methodology for calculating pollutant removal estiamtes and
plant compliance costs is discussed in Section X. Table X-2
shows the estimated pollutant removals for each treatment option
for direct dischargers. Compliance costs are presented in Table
X-3.
101
-------
BPT OPTION SELECTION
The technology basis for the BPT limitations is Option A, chemi-
cal precipitation and sedimentation technology to remove metals
and solids from combined wastewaters and to control pH, and oil
skimming to remove oil and grease. These technologies are not
in-place at the one discharger in this subcategory. The pollu-
tants specifically proposed for regulation at BPT are arsenic,
lead, mercury, silver, zinc, oil and grease, TSS, and pH.
Implementation of the proposed BPT limitations will remove
annually an estimated 914 kg of toxic metals and 334 kg of TSS.
We project a capital cost of $27,500 and an annualized cost of
$9,000 for achieving proposed BPT limitations.
More stringent technology options were not selected for BPT since
they require in-process changes or end-of-pipe technologies less
widely practiced in the subcategory, and, therefore, are more
appropriately considered under BAT.
WASTEWATER DISCHARGE RATES
A BPT discharge rate is calculated for each subdivision based on
the average of the flows of the existing plants, as determined
from analysis of the dcp. The discharge rate is used with the
achievable treatment concentration to determine BPT effluent
limitations. Since the discharge rate may be different for each
wastewater source, separate production normalized discharge rates
for each of the 11 wastewater sources are discussed below and
summarized in Table IX-1. The discharge rates are normalized on
a production basis by relating the amount of wastewater generated
to the mass of the intermediate product which is produced by the
process associated with the waste stream in question. These pro-
duction normalizing parameters, or PNP's, are also listed in
Table IX-1.
Section V of this supplement further describes the discharge flow
rates and presents the water use and discharge flow rates for
each plant by subdivision.
SMELTER WET AIR POLLUTION CONTROL
The BPT wastewater discharge rate for smelter wet air pollution
control is 13.2 liters per troy ounce (3.5 gal/troy ounce) of
gold and silver smelted, based on zero percent recycle. This
rate is allocated only for plants practicing wet air pollution
control for the smelter. Three plants reported this waste
stream, as shown in Table V-1. The BPT rate is based on the
average water use rate for these three plants (25.8, 8.4, and 5.3
liters per troy ounce).
102
-------
EPA is also considering a BPT wastewater discharge rate for this
waste stream of 1.32 liters per troy ounce, based on 90 percent
recycle. Recycle is demonstrated for this waste stream. EPA
will select between the two flow rates at promulgation, based on
public comment.
SILVER CHLORIDE REDUCTION SPENT SOLUTION
The BPT wastewater discharge rate for silver chloride reduction
spent solution is 0.4 liters per troy ounce (0.11 gal/troy ounce)
of silver reduced in solution. Water use and discharge rates are
presented in Table V-2. This normalized flow is based upon the
only reported value.
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL
The BPT wastewater discharge rate for the electrolytic cells wet
air pollution control is 198 liters per troy ounce (52.3 gal/troy
ounce) of gold refined electrolytically. This normalized flow is
based upon the only reported value for this subcategory. The
reported water use and discharge rates are presented in Table
V-3.
ELECTROLYTE PREPARATION WET AIR POLLUTION CONTROL
The BPT wastewater discharge rate for the electrolyte preparation
wet air pollution control is 0.05 liters per troy ounce (0.013
gal/troy ounce) of silver in the electrolyte produced. This
normalized flow is based upon the only value reported for this
subcategory. Water use and discharge rates are provided in Table
V-4.
SILVER CRYSTAL WASH WATER
The BPT wastewater discharge rate for silver crystal wash water
is 0.29 liters per troy ounce (0.08 gal/troy ounce) of silver
crystals washed. Table V-5 presents the water use and discharge
rates for this waste stream. The BPT rate is based on the only
reported value. This rate is allocated to any plant washing
silver crystals refined electrolytically.
GOLD SLIMES ACID WASH AND WATER RINSE
The BPT wastewater discharge rate for this waste stream is 4.0
liters per troy ounce (1.06 gal/troy ounce) of gold slimes
washed. This normalized flow is equivalent to the only value
reported for gold slimes acid wash and rinse waLer. Water use
and discharge rates are provided in Table V-6.
103
-------
CALCINER WET AIR POLLUTION CONTROL
The BPT wastewater discharge rate for the calciner wet air pol-
lution control is 186,200 1/kkg (49,200 gal/kkg) of mercury con-
densed. This normalized flow is based upon the sum of the flows
from three in-series scrubbers at the only facility reporting a
calciner scrubber (plant 1124). Table V-7 summarizes the water
use and discharge rates for this subdivision. This discharge
rate represents 16 percent recycle of scrubber liquor, which is
the rate currently achieved by the one plant with this stream.
CALCINE QUENCH WATER
The BPT wastewater discharge rate for calcine quench water is
17,600 1/kkg (4,650 gal/kkg) of mercury condensed. This produc-
tion normalized discharge rate is based upon the only reported
value for this waste stream. Water use and discharge rates are
presented in Table V-8.
CALCINER STACK GAS CONTACT COOLING WATER
The BPT wastewater discharge rate selected for calciner stack gas
contact cooling water is 4,150 1/kkg (1,096 gal/kkg) of mercury
condensed. This discharge rate is equivalent to the discharge
rate of the only plant reporting this waste stream. Table V-9
presents the reported water use and discharge rates for this
waste stream.
CONDENSER BLOWDOWN
The BPT wastewater discharge for condenser blowdown is 13,800
1/kkg (3,646 gal/kkg) of mercury condensed. Water use and dis-
charge rates for this waste stream are provided in Table V-10.
The condenser blowdown normalized discharge rate is based upon
the only value reported for this waste stream (plant 1068).
MERCURY CLEANING BATH WATER
The BPT wastewater discharge rate for mercury cleaning bath water
is 1,400 1/kkg (370 gal/kkg) of mercury condensed. This normal-
ized flow is equivalent to the only reported water discharge rate
for this waste stream. Table V-11 provides the reported water
use and discharge flows for this subdivision.
REGULATED POLLUTANT PARAMETERS
The raw wastewater concentrations from individual operations and
the subcategory as a whole were examined to select certain pollu-
tant parameters for limitation. This examination and evaluation
is presented in Sections VI and X. Eight pollutants or pollutant
104
-------
parameters are selected for limitation under BPT and are listed
below:
115.
122.
123.
126.
128.
arsenic
lead
mercury
silver
zinc
oil and grease
total suspended solids (TSS)
pH
EFFLUENT LIMITATIONS
The concentrations achievable by application of the proposed BPT
treatment are explained in Section VII of the General Development
Document and summarized there in Table VI1-19. The achievable
treatment concentrations (both one-day maximum and monthly aver-
age values) are multiplied by the BPT normalized discharge flows
summarized in Table IX-1 to calculate the mass of pollutants
allowed to be discharged per mass of product. The results of
these calculations in milligrams of pollutant per troy ounce or
kilogram of product represent the BPT effluent limitations and
are presented in Table IX-2 for each individual waste stream.
105
-------
T—
I
X
r-l
CU
r-l
&
CO
H
}_t
CU
^
r-l
•H
CO
ID
S
CO
-o
r-l
PH
2=
P-4
o
00
4-1
O
CU
CJ t3
>H C CU
Q^ rJ | i
O Or-l
O CU
W W >> B
33 H O co
H <3 rl
CJ 4J
P3 m
O S3
PX-I CO X-N
• 00
CO >H O J«S
pr"! flXj (J) • IK*
H S3 4J H —
<1 O CO ^r-<
PS p-5 PS r-l cO
W co 00
US CU 00
CJ 00^ rl
PS! Q MO
m
CO
< 23 cO
33 H O
PQ PS -n
^ ^
Is d
r-l r-l
PS r-l
P* O
e
cO
CU
M
4-1
CO
CU
4-1
CO
cO
^
cx
(_l
•rl
CO
4-1
CU
& r-l
O
CU 4-J
4J g
r-l 0
CU 0
CO
TJ
CU
CJ
d
TJ
cu
M
j_i
CU
^
r-4
•H
CO
4-i e
O 0
•rl
0.
r-l CO
•H
CO
T)
CU
C
•rl
V4-I
CU
M
Vj
0)
^ ^
r-l r-l
•H r-l
CO CO
CJ
4-1 -rl
0 4J
CU r-l
CJ O
C rl
d 4-1
0 CJ
cu
>~,r— 1
O 0)
l-l
4-1
CO
•
CN
m
00
CTi
r—
^
•H
CO
4J
CU
J3
i— 1
co O
r-l 4J
CU C
CJ 0
O
O
•rH f3
•u o
r-l 4-1
o d
rl r-l
4J r-l
0 O
CU CX
<— 1
U
1
O
CU
r-l
CU
c
•rl
VI
CU
^ *rj
r-l CU
•rl CJ
co d
T3
4-1 O
O M
cx
cu
CJ CU
C -u
Or-l
0
^M J-l
0 4-1
rl
4J
CO
^_
O
•
0
m
o
0
r-l
O
)_|
4-J
C C
0 0
•rl CJ
4-1
cO C
V4 0
cO T-I
p,4J
cu d
CXr-l
0
cu cx
t>~> M
1— 1 -rl
O CO
(_i
4-1 4-1
CJ CU
CU S
r-l
CO
r-l
CO
4J
co
t>-v
v^
o
)_l
CU
^
r-l
•rl
co
4-1
O
CU
o
C n3
d cu
0 XI
co
>>> cO
O £
rl
4-J
00
O
•
O
O*i
CN
•
O
l_l
x.
O
o
CN
M
CT>
^~
O
0
CN
.
vD
00
r-
C
O
•rl
4-1
rj
r-l
1— 1
o
CX
rl
•H
CO
4-1
CU
|3
r-|
rl 0
CU 1-4
C 4-1
•rl C
0 0
r-l CJ
CO
CJ
T3
CU
co
c
p^
^_
M
CU
4-1
CO
x:
t3
c
CU
d
cr
cu
c
•rl
CJ
r-l
CO
T3
CU
CO
C
T—
CU
4-1
CO
|3
XI
4-1
CO
Xi
00
C
•rl
C
cO
CU
r-l
O
>1
M
d
o
rl
cu
S
*— CN
co
in
oo
O »—
106
-------
Table IX-2
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 27.590 12.280
Lead 5.544 2.640
Mercury 3.300 1.320
Silver 5.412 2.244
Zinc 19.270 8.052
Oil and grease 264.000 158.400
Total suspended 541.200 257.400
solids
pH Within the range of 7.5 to 10.0
at.all times
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver reduced in solution
Arsenic 0.836 0.372
Lead 0.168 0.080
Mercury 0. 100 0.040
Silver 0.164 0.068
Zinc 0.584 0.244
Oil and grease 8.000 4.800
Total suspended 16.400 7.800
solids
pH Within the range of 7.5 to 10.0
at all times
107
-------
Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 413.800 184.100
Lead 83.160 39.600
Mercury 49.500 19.800
Silver 81.180 33.660
Zinc 289.100 120.800
Oil and grease 3,960.000 2,376.000
Total suspended 8,118.000 3,861.000
solids
pH Within the range of 7.5 to 10.0
at all times
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.105 0.047
Lead 0.021 0.010
Mercury 0.013 0.005
Silver 0.021 0.009
Zinc 0.073 0.031
Oil and grease 1.000 0.600
Total suspended 2.050 0.975
solids
pH Within the range of 7.5 to 10.0
at all times
108
-------
Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or
Pollutant Property
Maximum for
Any One Day
Maximum for
Monthly Average
ing/troy ounce of silver crystals washed
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
solids
PH
0.606
0.122
0.073
0.119
0.423
5.800
11.890
0.270
0.058
0.029
0.049
0.177
3.480
5.655
Within the range of 7.5 to 10.0
at all times
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or
Pollutant Property
Maximum for
Any One Day
Maximum for
Monthly Average
mg/troy ounce of gold slimes washed
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
solids
PH
8.360
680
000
640
840
80.000
164.000
1.
1.
1.
5.
3.720
0.800
0.400
0.680
2.440
48.000
78.000
Within the range of 7.5 to 10.0
at all times
109
-------
Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 388.800 173.000
Lead 78.120 37.200
Mercury 46.500 18.600
Silver 76.260 31.620
Zinc 271.600 113.500
Oil and grease 3,720.000 2,232.000
Total suspended 7,626.000 3,627.000
solids
pH Within the range of 7.5 to 10.0
at all times
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 36.790 16.370
Lead 7.392 3.520
Mercury 4.400 1.760
Silver 7.216 2.992
Zinc 25.700 10.740
Oil and grease 352.000 211.200
Total suspended 721.600 343.200
solids
pH Within the range of 7.5 to 10.0
at all times
110
-------
Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 8.674 3.860
Lead 1.743 0.830
Mercury 1.038 0.415
Silver 1.702 0.706
Zinc 6.059 2.532
Oil and grease 83.000 49.800
Total suspended 170.200 80.930
solids
pH Within the range of 7.5 to 10.0
at all times
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 28.840 12.830
Lead 5.796 2.760
Mercury 3.450 1.380
Silver 5.658 2.346
Zinc 20.150 8.418
Oil and grease 276.000 165.600
Total suspended 565.800 269.100
solids
pH Within the range of 7. 5 to 10.0
at all times
111
-------
Table IX-2 (Continued)
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(k) Mercury Cleaning Bach Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 2.926 1.302
Lead 0.588 0.280
Mercury 0.350 0.140
Silver 0.574 0.238
Zinc 2.044 0.854
Oil and grease 28.000 16.800
Total suspended 57.400 27.300
solids
pH Within the range of 7.5 to 10.0
at all times
112
-------
I
X
0)
00
• r-l
CO
H
CO
O
O
w
PS
PM
>> C6
PS O
gg
OS ^
P-4 CJ
W 3
PS PS
O 3
PS
53 53
W
35 Q
co <
H
a
w
53
H
W
8
C
O
•H
4J
3
i—I
1
<
to
0)
E
EH
PL,
PQ
113
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
The effluent limitations which must be achieved by July 1, 1984
are based on the best control and treatment technology used by a
specific point source within the industrial category or subcate-
gory, or by another category where it is readily transferable.
Emphasis is placed on additional treatment techniques applied at
the end of the treatment systems currently used, as well as
reduction of the amount of water used and discharged, process
control, and treatment technology optimization.
The factors considered in assessing best available technology
economically achievable (BAT) include the age of equipment and
facilities involved, the process used, process changes, nonwater
quality environmental impacts (including energy requirements),
and the costs of application of such technology (Section 304(b)
(2)(B) of the Clean Water Act). At a minimum, BAT represents the
best available technology economically achievable at plants of
various ages, sizes, processes, or other characteristics. Where
the Agency has found the existing performance to be uniformly
inadequate, BAT may be transferred from a different subcategory
or category. BAT may include feasible process changes or inter-
nal controls, even when not in common practice.
The statutory assessment of BAT considers costs, but does not
require a balancing of costs against pollutant removals (see
Weyerhaeuser v. Costle, 11 ERG 2149 (D.C. Cir. 1978)). However,
in assessing the proposed BAT, the Agency has given substantial
weight to the economic achievability of the technology.
TECHNICAL APPROACH TO BAT
The Agency reviewed a wide range of technology options and
evaluated the available possibilities to ensure that the most
effective and beneficial technologies were used as the basis of
BAT. To accomplish this, the Agency elected to examine three
technology options which could be applied to the primary precious
metals and mercury subcategory as alternatives for the basis of
BAT effluent limitations.
For the development of BAT effluent limitations, mass loadings
were calculated for each waslewater source or subdivision in the
subcategory using the same technical approach as described in
Section IX for BPT limitations development. The differences in
the mass loadings for BPT and BAT are due to increased treatment
115
-------
effectiveness achievable with the more sophisticated BAT treat-
ment technology and reductions in the effluent flows allocated to
various waste streams.
In summary, the treatment technologies considered for the primary
precious metals and mercury subcategory are:
Option A (Figure X-1):
• Oil skimming preliminary treatment for streams containing
oil and grease at treatable concentrations
• Chemical precipitation and sedimentation
Option B (Figure X-2) is based on
• In-process flow reduction of wet air pollution control
water
• Oil skimming preliminary treatment for streams containing
oil and grease at treatable concentrations
• Chemical precipitation and sedimentation
Option C (Figure X-3) is based on
• In-process flow reduction of wet air pollution control
water
• Oil skimming preliminary treatment for streams containing
oil and grease at treatable concentrations
• Chemical precipitation and sedimentation
• Multimedia filtration
The three options examined for BAT are discussed in greater
detail below. The first option considered is the same as the BPT
treatment technology which was presented in the previous section.
OPTION A
Option A for the primary precious metals and mercury subcategory
is equivalent to the control and treatment technologies which
were analyzed for BPT in Section IX. The BPT end-of-pipe treat-
ment scheme includes chemical precipitation and sedimentation
(lime and settle) technology, with oil skimming preliminary
treatment of wastewaters containing treatable concentrations of
oil and grease (see Figure X-1). The discharge rates for Option
A are equal to the discharge rates allocated to each stream as a
BPT discharge flow.
OPTION B
Option B for the primary precious metals and mercury subcategory
achieves lower pollutant discharge by building upon the Option A
116
-------
(oil skimming preliminary treatment, chemical precipitation and
sedimentation) treatment technology. Flow reduction measures are
added to the Option A treatment scheme (see Figure X-2). These
flow reduction measures, including in-process changes, result in
the concentration of pollutants in some wastewater streams. As
explained in Section VII of the General Development Document,
treatment of a more concentrated effluent allows achievement of a
greater net pollutant removal and introduces the possible eco-
nomic benefits associated with treating a lower volume of
wastewater.
Option B flow reduction measures are reflected in the BAT waste -
water discharge rates. Flow reduction has been included in
determining the BAT discharge rates for smelter wet air pollution
control, electrolytic cells wet air pollution control, and cal-
ciner wet air pollution control. Based on available data, the
Agency did not feel that further flow reduction over BPT would be
feasible for the remaining eight waste streams in the primary
precious metals and mercury subcategory. These waste streams
are:
1. Silver.chloride reduction spent solution,
2. Electrolyte preparation wet air pollution control,
3. Silver crystal wash water,
4. Gold slimes acid wash and water rinse,
5. Calcine quench water,
6. Calciner stack gas contact cooling water,
7. Condenser blowdown, and
8. Mercury cleaning bath water.
Flow reduction measures used in Option B to reduce process
wastewater generation or discharge rates include the following:
Recycle of Water Used in Wet Air Pollution Control
There are four wastewater sources associated with wet air pollu-
tion control which are regulated under the primary precious
metals and mercury subcategory:
1. Smelter wet air pollution control,
2. Electrolytic cells wet air pollution control,
3. Electrolyte preparation wet air pollution control, and
4. Calciner wet air pollution control.
Table X-1 presents the number of plants reporting wastewater from
the wet air pollution control sources listed above, the number of
plants practicing recycle, and the range of recycle values being
listed. Recycle of smelter scrubber water, electrolytic cell
scrubber water, and calciner scrubber water are required for BAT.
Recycle of electrolyte preparation wet air pollution control is
117
-------
not required for BAT because the BPT discharge flow is close to
the minimum possible water discharge from a scrubber. The recycle
rate used for all three other sources is based on 90 percent
recycle of the average water use reported by all the plants with
each waste stream, as will be shown later.
OPTION C
Option C for the primary precious metals and mercury subcategory
consists of all control and treatment requirements of Option B
(in-process flow reduction, oil skimming preliminary treatment,
chemical precipitation and sedimentation) plus multimedia filtra-
tion technology added at the end of the Option B treatment scheme
(see Figure X-3). Multimedia filtration is used to remove sus-
pended solids, including precipitates of toxic metals, beyond the
concentration attainable by gravity sedimentation. The filter
suggested is of the gravity, mixed media type, although other
filters, such as rapid sand filters or pressure filters, would
perform satisfactorily.
INDUSTRY COST AND ENVIRONMENTAL BENEFITS
As one means of evaluating each technology option, EPA developed
estimates of the pollutant removal benefits and the compliance
costs associated with each option. The methodologies are
described below.
POLLUTANT REMOVAL ESTIMATES
A complete description of the methodology used to calculate the
estimated pollutant removal, or benefit, achieved by the applica-
tion of the various treatment options is presented in Section X
of the General Development Document. In short, sampling data
collected during the field sampling program were used to charac-
terize the major waste streams considered for regulation. At
each sampled facility, the sampling data was production normal-
ized for each unit operation (i.e., mass of pollutant generated
per mass of product manufactured). This value, referred to as
the raw waste, was used to estimate the mass of toxic pollutants
generated within the primary precious metals and mercury subcate-
gory. The pollutant removal estimates were calculated for each
plant by first estimating the total mass of each pollutant in the
untreated wastewater. This was calculated by first multiplying
the raw waste values by the corresponding production value for
that stream and then summing these values for each pollutant for
every stream generated by the plant.
Next, the volume of wastewater discharged after the application
of each treatment option was estimated for each operation at each
plant by comparing the actual discharge to the regulatory flow.
118
-------
The smaller of the two values was selected and summed with the
other plant flows. The mass of pollutant discharged was then
estimated by multiplying the achievable concentration values
attainable with the option (mg/1) by the estimated volume of
process wastewater discharged by the subcategory. The mass of
pollutant removed is the difference between the estimated mass of
pollutant generated within the subcategory and the mass of
pollutant discharged after application of the treatment option.
The pollutant removal estimates for direct dischargers in the
primary precious metals and mercury subcategory are presented in
Table X-2.
COMPLIANCE COSTS
In estimating subcategory-wide compliance costs, the first step
was to develop a cost estimation model, relating the total costs
associated with installation and operation of wastewater treat-
ment technologies to plant process wastewater discharge. EPA
applied the model to each plant. The plant's investment and
operating costs are determined by what treatment it has in place
and by its individual process wastewater discharge flow. As dis-
cussed above, this flow is either the actual or the BAT regula-
tory flow, whichever is lesser. The final step was to annualize
the capital costs, and to sum the annualized capital costs, and
the operating and maintenance costs for each plant, yielding the
cost of compliance for the subcategory (see Table X-3). These
costs were used in assessing economic achievability.
BAT OPTION SELECTION
Our proposed BAT limitations for this subcategory are based on
preliminary treatment consisting of oil skimming and end-of-pipe
treatment consisting of chemical precipitation and sedimentation
(BPT technology), and filtration (Option C).
The pollutants specifically limited under BAT are arsenic, lead,
mercury, silver, and zinc. The toxic pollutants cadmium, chro-
mium, copper, nickel, and thallium were also considered for regu-
lation because they were found at treatable concentrations in the
raw wastewaters from this subcategory. These pollutants were not
selected for specific regulation because they will be effectively
controlled when the regulated toxic metals are treated to the
concentrations achievable by the model BAT technology.
Implementation of the proposed BAT limitations would remove annu-
ally an estimated 914.5 kg of toxic metals. Estimated capital
cost for achieving proposed BAT is $30,000 and annualized cost is
$10,000.
119
-------
Oil skimming is demonstrated in the nonferrous metals manufactur-
ing category. Although no primary precious metals and mercury
plants have oil skimming in place, it is necessary to reduce oil
and grease concentrations in the discharge from this subcategory.
WASTEWATER DISCHARGE RATES
A BAT discharge rate was calculated for each subdivision based
upon the flows of the existing plants, as determined from analy-
sis of the data collection portfolios. The discharge rate is
used with the achievable treatment concentrations to determine
BAT effluent limitations. Since the discharge rate may be dif-
ferent for each wastewater source, separate production normalized
discharge rates for each of the 11 wastewater sources were deter-
mined and are summarized in Table X-4. The discharge rates are
normalized on a production basis by relating the amount of waste-
water generated to the mass of the intermediate product which is
produced by the process associated with the waste stream in ques-
tion. These production normalizing parameters (PNP) are also
listed in Table X-4.
As discussed previously, the BAT wastewater discharge rate equals
the BPT wastewater discharge rate for eight of the 11 waste
streams in the primary precious metals and mercury subcategory.
Based on the available data, the Agency determined that further
flow reduction would not be feasible for these eight wastewater
sources. Wastewater streams for which BAT discharge rates differ
from BPT are discussed below.
SMELTER WET AIR POLLUTION CONTROL
The BAT wastewater discharge rate for smelter wet air pollution
control is 1.3 liters per troy ounce of gold and silver smelted.
This rate is based on 90 percent recycle of the average water use
rate reported for this waste stream, as shown in Table V-1. This
rate corresponds to 90 percent recycle of the BPT discharge rate.
As shown in Table VI-1, recycle is demonstrated for this stream.
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL
The BAT wastewater discharge rate for electrolytic cells wet air
pollution control is 19.8 liters per troy ounce of gold refined
electrolytically. This rate is based on 90 percent recycle of
the water use rate reported by the one plant with this waste
stream, as shown in Table V-3. The Agency believes this waste
stream can be operated with 90 percent recycle, even though
recycle is noL demonstrated for it.
120
-------
CALGINER WET AIR POLLUTION CONTROL
The BAT wastewater discharge rate for calciner wet air pollution
control is 22,000 liters per metric ton of mercury condensed.
This rate is based on 90 percent recycle of the water use rate
reported by the only plant with this waste stream. As shown in
Table V-7, the plant reported a flow of 186,000 1/kk.g, which
represents a 16 percent recycle rate. The BAT rate was
determined by the following formula:
(186,000 1/kkg) (1.00 - 0.90) = 22,000 1/kkg
(1.00 - 0.16)
Although 90 percent recycle is not demonstrated for this waste
stream, the Agency believes it is achievable.
REGULATED POLLUTANT PARAMETERS
In implementing the terms of the Consent Agreement in NRDC v.
Train, Op. Cit., and 33 U. S.C. §1314(b) (2) (A and B) (11T767, the
Agency placed particular emphasis on the toxic pollutants. The
raw wastewater concentrations from individual operations and the
subcategory as a whole were examined to select certain pollutant
parameters for consideration for limitation. This examination
and evaluation, presented in Section VI, concluded that 10 pollu-
tants are present in primary precious metals and mercury waste-
waters at concentrations than can be effectively reduced by
identified treatment technologies (refer to Section VI).
The high cost associated with analysis for toxic metal pollutants
has prompted EPA to develop an alternative method for regulating
and monitoring toxic pollutant discharges from the nonferrous
metals manufacturing category. Rather than developing specific
effluent mass limitations and standards for each of the toxic
metals found in treatable concentrations in the raw wastewaters
from a given subcategory, the Agency is proposing effluent mass
limitations only for those pollutants generated in the greatest
quantities as shown by the pollutant removal analysis. The
pollutants selected for specific limitation are listed below:
115. arsenic
122. lead
123. mercury
126. silver
128. zinc
By establishing limitations and standards for certain toxic metal
pollutants, dischargers will attain the same degree of control
over toxic metal pollutants as they would have been required to
achieve had all the toxic metal pollutants been directly limited.
121
-------
This approach is technically justified since the treatable con-
centrations used for chemical precipitation and sedimentation
technology are based on optimized treatment for concomitant
multiple metals removal. Thus, even though metals have somewhat
different theoretical solubilities, they will be removed at very
nearly the same rate in a chemical precipitation and sedimenta-
tion treatment system operated for multiple metals removal.
Filtration as part of the technology basis is likewise justified
because this technology removes metals non-preferentially.
The toxic metal pollutants selected for specific limitation in
the primary precious metals and mercury subcategory to control
the discharges of toxic metal pollutants are arsenic, lead,
mercury, silver, and zinc.
The following toxic pollutants are excluded from limitation on
the basis that they are effectively controlled by the limitations
developed for arsenic, lead, mercury, silver, and zinc:
118. cadmium
119. chromium
120. copper
124. nickel
127. thallium
EFFLUENT LIMITATIONS
The treatable concentrations, achievable by application of the
BAT technology (Option C), are summarized in Table VII-19 of the
General Development Document. These treatable concentrations
(both one-day maximum and monthly average) are multiplied by the
BAT normalized discharge flows summarized in Table X-4 to calcu-
late the mass of pollutants allowed to be discharged per mass of
product. The results of these calculations in milligrams of
pollutant per troy ounce or kilogram of product represent the BAT
effluent limitations for the primary precious metals and mercury
subcategory. BAT effluent limitations based on Option C (oil
skimming, chemical precipitation, sedimentation, in-process flow
reduction, and multimedia filtration) are presented in Table X-5.
122
-------
Table X-1
CURRENT RECYCLE PRACTICES WITHIN THE PRIMARY
PRECIOUS METALS AND MERCURY SUBCATEGORY
Smelter wet air pollution
control
Electrolytic cells wet
air pollution control
Electrolyte preparation
wet air pollution
control
Calciner wet air pollution
control
Number of
Plants With
Wastewater
3
1
1
Number
of Plants
Practicing
Recycle
0
0
Range
of Recycle
Values (%)
76-100
0
0
16
123
-------
CM
I
X
(U
u
§01 IJ
> >1
fl O **•*
u B ot
a, 01 x
O 35 ^^
01
U 00
B !
•U CO 01
O H) ~^s
CO
B 01 IJ
0 > >>
ft O--
4-1 B at
£=se
01
ao ao
C td ^*
O JS >i
u to at
O O •*-'
"*TJ^
B w'ij'
o > >.
•u B at
Ou (U ^
0)
< ao
E 03 Vj
O JS >i
4J CO 01
01
09 VJ
CO >,
00
OS
U
B
eg
4J
3
— t
—l
O
CL,
»O ^ CM
COO -O
— r-» CM
cor-I d
«- ao
30
3O — ON
P~ O CM
CM CM O
odd
00-*
io to •••ij
O\OCM
aOr-!d
— ao
-* CMP^
— 0-*
-a-coo
• odd
o o-a-
O vOCM
ao r*- O
•— ao
so
•- o -a-
-*COO
odd
m CM —
-a-OlCM
ao r^d
— ao
co
>>
i-s!
U 09T3
< < O
UO CO CO
UO *— vO
CO ^" CO
O-*O -^CM
*— t^r-
CO -^ CM
CM O O
o do do
CM ON ON
^f 3O ^f
IN O CO
^3 "^ ^3 ^™ ^^
CO — vO
-^ r~ co
CO 00
odo do
CM ON ON
*^ ao -^
CM O CO
O >* O ~- CM
CO «— ^O
-* r* co
CO O O
odo do
ao vO GO
in —co
O -* O ^- CS
2 ^
9 ^
U tO
O <-*
tt °
**^
3 0) >
o O.'BTS c
U D. « C8 (-
O O O J Z
CO
-o
0 OOO O
CO ^
O CO
o —
O OOO O
ON
o
o o o o o
co m
O O1
o •-
OOOO 0
ON
o
~*
o o o o o
co in
C5 ON
0 —
OOOO O
CO IT!
0 0
^3 \O
O OOO O
E e
. 3 3
5 S >d o
O -4.-I (8 B
fl 01 •»< f fl
Z CO CO IH M
ON
5
2
ON
ao
ON
o
-a-
0\
co
,«
ON
CM
•*
—
^.
CO
CO
^.
ON
CM
•*
—
ON
CO
m
,_
OS
en
o
X
8
^
g
H
'•O .
CMO
CO
CO
CO >*
mo
*-o
CM —
— o
coo
CO
CO
co r—
o -*
— o
r>-o
CM —
*~ o
r^O
coo
CO
CO
cor--
o ^a*
— 0
r~o
moo
COO
o o
^
CO
01
01
OS
01
o
•o
n)
CO ft
HO
r>»
r**
CM
Oi
CO
CO
vO
CO
m
—
CO
y_
"^
CO
CO
CO
O
*-
r*
CO
^
^
CO
CO
CO
o
—
1^
CO
vO
co
o
x^
co
S3
o
l-t
C-l
Z
M
Z
o
o
<
S
H
NO
CM
p^
CO
m
CM
1"—
-a-
CO
CM
^
ON
(^
^
CM
.
CM
NO
ao
^
ON
vO
T-^
^3-
CM
.
*~
CM
vO
m
ao
ON
m
CM
vO
m
CM
j_a
H
Z
^J
^4
3
J
-I
£
^
0
H
E
O
4J
rt
u
01
S
T3
§
O
4-1
ft
a.
o
01
03
O
01
00
c
B
m
O
a.
0
B
O
to
4->
B
B
•O
01
09
T3
03
B
O
fl
4-1
03
4-1
O
0)
to
O
E
0)
ao
i
o
o
a
o
on
ra
'•H
T3
OS
c
o
4-1
03
B
01
T3
01
a
•a
§.
o
o
a>
1-1
a.
a)
O
00
c
o
o
•a
0)
tb
o
fi
4-1
a.
o
124
-------
Table X-3
COST OF COMPLIANCE FOR DIRECT DISCHARGERS IN THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
Total Required
Capital Cost
Option (1982 Dollars)
A 27,500
B 27,500
C 30,000
Total
Annual Cost
(1982 Dollars)
9,000
9,000
10,000
125
-------
^3"
1
X
O)
rH
Xl
cd
H
rl
OI
^
i-H
•rl
CO
•o
n
cd
TJ
rH
0-.
53
OH
Q
00
14H
O
01
O TJ
>H n cu
PS 3 i |
O O rH
O Oi
Cd W >% B
?3 H O CD
H H O .*
W PS O> • r*S
HO 4J H ^
-l O
PQ PS .rl
<£ 4-1
3s 3
M rH
PS rH
0-. O
B
cu
rl
4J
CO
01
4J
co
cd
^
P,
rl
•H
Oj
4J
^
S rH
O
01 4.)
4J g
r-l O
OI O
B
TJ
CD
O
rj
TJ
CU
Vl
rl
CU
^
rH
.,_!
CO
MH C
0 0
•H
OI 4-)
O 3
CrH
3 0
O CO
^*» C
O -H
Vl
4J
^~
r—
•
O
^»
•
o
Jj
o
•H
4J
O
rj
TJ
0*
rl
C
01 O
T3 -H
•H 4-1
rl 3
O rH
rH 0
Si co
O
4-1
rl C
Oi 0,
i-H CO
•H
CO
T3
CU
C
•H
MH
0)
rl
t3 ^
rH rH
O rH
00 Cd
CJ
H | -T^
O 4J
>^
CU rH
0 0
C rl
0 4-)
0 0
CU
o cu
rl
4J
CO
CN
•
m
00
CT\
T—
^(
•H
cd
4->
O>
[5
rH
CO O
rH VJ
rH 4J
Oi C
0 0
o
o
•iH C
4J 0
rH *4J
o ^
rl rH
4-» rH
0 0
cu ex
i-H
W
1
o
cu
rH
01
G
^_l
cu
^ T3
rH CU
•H O
CO 3
*O
UH O
O rl
cx
cu
U CU
C 4->
0 r**»
OrH
0
>x rl
O 4J
rl
4J
CO
r—
O
•
o
m
o
o
rH
o
rl
4-J
c c
0 0
•rl O
4-J
cd c
rl 0
cd -H
CX 4J
oi 3
CXrH
0
CU O'
[ 1
fx, >_|
rH -H
O cd
rl
4-> 4-1
O
CN
•
o
rl
01
4-)
cd
5
r^
co
cd
^
rH
cd
4J
CO
^
rl
CJ
rl
CU
^
rH
•H
CO
CO
CU
S
•H
rH
CO
T3
rH
O
00
<4-t
O
CU
O
CT>
rj 01
OX!
co
^-» cd
o I?
rl
4_)
vO
O
i—
O
-3-
T3
C
cd
t-\
co
cd
T3
•H
CJ
cd cu
CO
co G
01 -H
B rl
•rl
rH rl
•o (11
" 4-1
*T3 cd
rH ?
O
O
TJ
CU
CO
c
cu
TJ
C
o
CJ
^>
rl
rj
CJ
rl
CU
B
<4H
O
00
^
Wt
CN
r-
00
•
m
o
o
o
•
CN
CN
n
o
•rl
4-)
rj
rH
i-H
O
cx
rl
•H
cd
4-1
CU
3
rH
rl O
CU rl
C 4->
•H C
0 0
rH 0
Cd
0
TD
CU
co
c
cu
T)
c
o
CJ
^>
rl
rj
CJ
rl
CU
B
MH
O
00
y
v>
O
m
vO
•
•^~
O
0
vO
•
r^
T—
rl
OI
4-)
cd
r1,
CJ
C
CU
rj
cr
OI
C
•H
0
rH
cd
u
T)
cu
CO
c
cu
T3
C
o
CJ
^>
Vl
rj
CJ
rl
OI
B
UH
0
00
^
vO
CTi
O
-
»—
O
m
T—
•
-^~
4-1
CJ
cd
4J
G
O
O
co
cd
00
•J,
o
cd
4->
CO
rl
CU
G
•iH
O
rH
cd
o
rl
CU
4-)
cd
15
00
c
•H
1— 1
o
o
CJ
T3
O)
co
G
0)
X)
c
o
CJ
^>
rl
0
o
Vi
cu
e
U-)
0
00
s^
T*^
v^5
%^
v^3
-
CO
o
o
oo
•
co
»—
c
3
o
T>
o
rH
43
rl
CU
CO
G
cu
-o
G
0
CO
TJ
CU
CO
G
CU
T3
C
O
o
^~>
Vi
rj
O
Vi
cu
B
m
o
00
y
y
0
r-»
CO
o
o
vj-
•>
r—
S-l
cu
4-1
cd
S
j2
4-)
cd
Xi
00
c
•rl
P
cd
cu
rH
CJ
>•>
Vi
d
o
Vi
cu
S
CN
m
oo o\
O T-
126
-------
Table X-5
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of gold and
1.807
0.364
0.195
0.377
1.326
silver smelted
0.806
0.169
0.078
0.156
0.546
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver reduced
0.556
0.112
0.060
0.116
0.408
in solution
0.248
0.052
0.024
0.048
0.168
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 12.280
Lead 5. 544 2.574
Mercury 2.970 1.188
Silver 5.742 2.376
Zinc 20.200 8.316
127
-------
Table X-5 (Continued)
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.070 0.031
Lead 0.014 0.007
Mercury 0.008 0.003
Silver 0.015 0.006
Zinc 0.051 0.021
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.403 0.180
Lead 0.081 ' 0.038
Mercury 0.044 0.017
Silver 0.084 0.035
Zinc 0.296 0.122
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold slimes washed
Arsenic 5.560 "2.480
Lead 1.120 0.520
Mercury 0.600 0.240
Silver 1.160 0.480
Zinc 4.080 1.680
128
-------
Table X-5 (Continued)
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
rog/kg (Ib/million Ibs) of mercury condensed
Arsenic 30.580 13.640
Lead 6. 160 2.860
Mercury 3.300 1.320
Silver 6.380 2.640
Zinc 22.440 9.240
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 2.112
Zinc 17.950 7.392
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 5.769 2.573
Lead 1. 162 0. 540
Mercury 0.623 0.249
Silver 1.204 0.498
Zinc 4.233 1.743
129
-------
Table X-5 (Continued)
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million
Ibs) of mercury
19.180
3.864
2.070
4.002
14.080
condensed
8.556
1.794
0.828
1.656
5.796
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 0.168
Zinc 1.428 0.588
130
-------
X
0)
M
3
00
55
O
H
PL,
O
OS
O
fa
Ed
a
a
en
H
2;
CQ
T
•H
I*
a
u
o;
4J
Q
3
•o
VH
5
01
H
W
131
-------
si
O H
CQ
a
o
O-i
O
O
CN fa
X W
cu
S-i
w
IT!
00 CO
£IH r j
a
CQ
•o
<-(
o
o
3 5
132
-------
Ml
oo
i
X!
-------
134
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
The basis for new source performance standards (NSPS) under
Section 306 of the Act is the best available demonstrated tech-
nology (BDT). New plants have the opportunity to design the best
and most efficient production processes and wastewater treatment
technologies without facing the added costs and restrictions
encountered in retrofitting an existing plant. Therefore,
Congress directed EPA to consider the best demonstrated process
changes, in-plant controls, and end-of-pipe treatment techno-
logies which reduce pollution to the maximum extent feasible.
This section describes the technologies for treatment of waste-
water from new sources and presents mass discharge standards for
regulatory pollutants for NSPS in the primary precious metals and
mercury subcategory, based on the selected treatment technology.
TECHNICAL APPROACH TO NSPS
New source performance standards are equivalent to the best
available technology (BAT) selected for currently existing
primary precious metals and mercury plants. This result is a
consequence of careful review by the Agency of a wide range of
technical options for new source treatment systems which is
discussed in Section XI of the General Development Document.
This review of the primary precious metals and mercury subcate-
gory found no new, economically feasible, demonstrated technolo-
gies which could be considered an improvement over those chosen
for consideration for BAT. Additionally, there was nothing found
to indicate that the wastewater flows and characteristics of new
plants would not be similar to those from existing plants, since
the processes used by new sources are not expected to differ from
those used at existing sources. Consequently, BAT production
normalized discharge rates, which are based on the best existing
practices of the subcategory, can also be applied to new sources.
These rates are presented in Table XI-1.
Treatment technologies considered for the NSPS options are
identical to the treatment technologies considered for the BAT
options. These options are:
OPTION A
Preliminary treatment with oil skimming (where required)
Chemical precipitation and sedimentation
135
-------
OPTION B
• Preliminary treatment with oil skimming (where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of smelter, electrolytic cells,
and calciner scrubber liquor
OPTION C
• Preliminary treatment with oil skimming (where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of smelter, electrolytic cells,
and calciner scrubber liquor
• Multimedia filtration
NSPS OPTION SELECTION
We are proposing that NSPS be equal to BAT. Our review of the
subcategory indicates that no new demonstrated technologies that
improve on BAT technology exist. We do not believe that new
plants could achieve any flow reduction beyond the allowances
proposed for BAT. Because NSPS is equal to BAT we believe that
the proposed NSPS will not have a detrimental impact on the entry
of new plants into this subcategory.
REGULATED POLLUTANT PARAMETERS
The Agency has no reason to believe that the pollutants that will
be found in treatable concentrations in processes within new
sources will be any different than with existing sources.
Accordingly, pollutants and pollutant parameters selected for
limitation under NSPS, in accordance with the rationale of
Sections VI and X, are identical to those selected for BAT. The
conventional pollutant parameters oil and grease, TSS, and pH are
also selected for limitation.
NEW SOURCE PERFORMANCE STANDARDS
The NSPS discharge flows for each wastewater source are the same
as the discharge rates for BAT and are shown in Table XI-1. The
mass of pollutant allowed to be discharged per mass of product is
calculated by multiplying the appropriate treatable concentration
(mg/1) by the production normalized wastewater discharge flows
(1/T.O. or 1/kkg). The treatable concentrations are listed in
Table VII-19 of the General Development Document. The results of
these calculations are the production-based new source perfor-
mance standards. These standards are presented in Tables XI-2.
136
-------
CO
T—
|
rH
X
CU
rH
Xt
cO
H
CU
>
rH
•r-l
CO
TJ
G
CO
13
r_|
PH
53
P-I
0
00
MH
O
cu
O 13
>" C CU
Pi 3 4->
O O rH
O CU
w w >s B
W H 0 co
H H Or*
w Pi cu • ^
HO 4J H ^>
<$ CJ CO ^rH
OS Pi Pi rH CO
W CO OC
w S _,
W O 0
co
•
1—
H rH
co cj
< w
:s pi
PH
CO C
PH JM 0
co oi .,_i
53 < 4->
S 3
rH rH
Pi rH
P-i O
B
cO
CU
rl
4-1
CO
CU
4J
CO
cO
*»
ex
VH
•r-l
CO
4-1
CU
15 rH
O
VH V-i
CU 4J
4-> C
rH 0
CU O
a
cB
13
CU
O
3
13
CU
V-i
VH
CU
>
rH
•iH
co
MH C
0 0
•rH
CU 4J
O 3
fir-H
3 O
O CO
xc
O iH
VH
4-1
r—
^
•
O
0
3
13
CU
V-i
C
cu o
13 -rH
•rl 4-1
rH 3
OrH
rH O
XI »
O
4J
S-i C
cu cu
> ex
rH CO
•rH
CO
13
CU
C
•rl
MH
cu
VH
T3 X
rH rH
O rH
00 CO
CJ
MH -H
0 4J
>•»
CU rH
O O
G IH
3 4J
0 0
CU
>>rH
O CU
IH
4-1
CO
CN
•
m
00
•
CTi
T—
VH
•rH
CO
4J
r"
£
rH
co o
rH V,
rH 4J
cu c
0 o
O
o
•H C
4-> O
^vH
rH 4J
0 3
H rH
4-> rH
0 0
cu a
rH
tt
CJ
CU
rH
CU
c
•rl
IH
CU
>TJ
rH CU
•rH O
CO 3
13
MH O
O VH
tx
CU
CJ CU
C4J
3 K>~.
OrH
O
Xrl
04-1
IH
4-)
co
^_
0
•
O
m
o
•
o
rH
O
VH
4->
C C
O O
.rH 0
4-1
cO G
VH 0
CO'iH
CX4->
CU 3
rlrH
CXrH
0
CU (X
4-1
E>»rH
rH-rl
O CO
IH
4-1 4->
O CU
CU $
r-l
M
rH
CO
4J
CO
>s
VH
CJ
VH
CU
>
rH
•rH
CO
MH
O
cu
CJ
C 13
3 CU
0 X!
co
XcO
0 £
VH
4J
00
O
•
0
Oi
CM
•
O
VH
CU
4J
JO
S
X!
co
CO
S
rH
CO
4J
co
X
S-I
CJ
IH
rH
•H
CO
CO
cu
S
•rl
rH
co
13
rH
O
00
MH
O
cu
CJ
C 13
3 cu
OX!
co
>-, °3
0 &
IH
4-1
V£>
0
*
T—
O
•
i
VH
3
O
VH
CU
B
MH
O
00
^
r*
CN
^~
OO
•
in
0
o
o
.
CN
CN
G
O
•rH
4-1
3
rH
rH
O
a,
VH
•rH
CO
4-1
CU
S
rH
VH O
CU VH
G 4J
•H C
0 0
rH 0
cO
0
13
cu
CO
c
cu
13
c
o
o
>s
VH
3
CJ
VH
CU
S
MH
O
00
^
r*
O
in
vO
M
C
o
o
CO
cd
00
VH
£> 0)
O 4J
cO cO
4-> ^
CO
00
VH C!
CU-rH
G<->
•rH O
CJ 0
rH 0
cO
CJ
13
cu
co
c
cu
13
C
O
o
X
IH
3
O
VH
CU
B
MH
O
00
^
r*
v£>
-------
Table XI-2
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
S UBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 1.807 0.806
Lead 0.364 0.169
Mercury 0.195 0.078
Silver 0.377 0.156
Zinc 1.326 0.546
Oil and grease 13.000 13.000
Total suspended 19.500 15.600
solids
pH Within the range of 7.5 to 1 0. 0
at all times
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver reduced in solution
Arsenic 0.556 0.248
Lead 0.112 0.052
Mercury 0.060 0.024
Silver 0.116 0.048
Zinc 0.408 0.168
Oil and grease 4.000 4.000
Total suspended 6.000 4.800
solids
pH Within the range of 7.5 to 10.0
at all times
138
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 . 12.280
Lead 5.544 2.574
Mercury 2.970 1.188
Silver 5.742 2.376
Zinc 20.200 8.316
Oil and grease 198.000 198.000
Total suspended 297.000 237.600
solids
pH Within the range of 7.5 to 10.0
at all times
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.070 0.031
Lead 0.014 0.007
Mercury 0.008 0.003
Silver 0.015 0.006
Zinc 0.051 0.021
Oil and grease 0.500 0.500
Total suspended 0.750 0.600
solids
pH Within the range of 7.5 to 10.0
at all times
139
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.403 0.180
Lead 0.081 0.038
Mercury 0.044 0.017
Silver 0.084 0.035
Zinc 0.296 0.122
Oil and grease 2.900 2.900
Total suspended 4.350 3.480
solids
pH Within the range of 7.5 to 10.0
at all times
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold slimes washed
Arsenic 5.560 2.480
Lead 1.120 0.520
Mercury 0.600 0.240
Silver 1.160 0.480
Zinc 4.080 1.680
Oil and grease 40.000 40.000
Total suspended 60.000 48.000
solids
pH Within the range of 7.5 to 10.0
at all times
140
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 30.580 13.640
Lead 6.160 2.860
Mercury 3.300 1.320
Silver 6.380 2.640
Zinc 22.440 9.240
Oil and grease 220.000 220.000
Total suspended 330.000 264.000
solids
pH • Within the range of 7.5 to 10.0
at all times
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
(Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 . 2.112
Zinc 17.950 7.392
Oil and grease 176.000 176.000
Total suspended 264.000 211.200
solids
pH Within the range of 7.5 to 10.0
at all times
141
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
fflg/kg (Ib/million Ibs) of mercury condensed
Arsenic 5.769 2.573
Lead 1.162 0.540
Mercury 0.623 0.249
Silver 1.204 0.498
Zinc 4.233 1.743
Oil and grease 41.500 41.500
Total suspended 62.250 49.800
solids
pH Within the range of 7.5 to 10.0
at all times
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 19.180 8.556
Lead 3.864 1.794
Mercury 2.070 0.828
Silver 4.002 1.656
Zinc 14.080 5.796
Oil and grease 138.000 138.000
Total suspended 207.000 165.600
solids
pH Within the range of 7.5 to 10.0
at all times
142
-------
Table XI-2 (Continued)
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 0.168
Zinc 1.428 0.588
Oil and grease 14.000 14.000
Total suspended 21.000 16.800
solids
pH Within the range of 7.5 to 10.0
at all times
143
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION XII
PRETREATMENT STANDARDS
Section 307(b) of the Act requires EPA to promulgate pretreatment
standards for existing sources (PSES), which must be achieved
within three years of promulgation. PSES are designed to prevent
the discharge of pollutants which pass through, interfere with,
or are otherwise incompatible with the operation of publicly
owned treatment works (POTW). The Clean Water Act of 1977
requires pretreatment for pollutants, such as heavy metals, that
limit POTW sludge management alternatives. Section 307(c) of the
Act requires EPA to promulgate pretreatment standards for new
sources (PSNS) at the same time that it promulgates NSPS. New
indirect discharge facilities, like new direct discharge facili-
ties, have the opportunity to incorporate the best available
demonstrated technologies, including process changes, in-plant
controls, and end-of-pipe treatment technologies, and to use
plant site selection to ensure adequate treatment system instal-
lation. Pretreatment standards are to be technology based,
analogous to the best available technology for removal of toxic
pollutants.
EPA is not proposing pretreatment standards for existing sources
in this subcategory because no indirect dischargers exist. How-
ever, EPA is proposing pretreatment standards for new sources
because plants may be constructed in the future which may
discharge to a POTW.
This section describes the control and treatment technologies for
pretreatment of process wastewaters from new sources in the
primary precious metals and mercury subcategory. Pretreatment
standards for regulated pollutants are presented based on the
selected control and treatment technology.
TECHNICAL APPROACH TO PRETREATMENT
Before proposing pretreatment standards, the Agency examines
whether the pollutants discharged by the industry pass through
the POTW or interfere with the POTW operation or its chosen
sludge disposal practices. In determining whether pollutants
pass through a well-operated POTW, achieving secondary treatment,
the Agency compares the percentage of a pollutant removed by POTW
with the percentage removed by direct dischargers applying the
best available technology economically achievable. A pollutant
is deemed to pass through the POTW when the average percentage
removed nationwide by well-operated POTW meeting secondary
145
-------
treatment requirements, is less than the percentage removed by
direct dischargers complying with BAT effluent limitations
guidelines for that pollutant. (See generally, 46 FR at 9415-16
(January 28, 1981)).
This definition of pass through satisfies two competing objec-
tives set by Congress: (1) that standards for indirect dis-
chargers be equivalent to standards for direct dischargers while
at the same time, (2) that the treatment capability and perfor-
mance of the POTW be recognized and taken into account in regu-
lating the discharge of pollutants from indirect dischargers.
The Agency compares percentage removal rather than the mass or
concentration of pollutants discharged because the latter would
not take into account the mass of pollutants discharged to the
POTW from non-industrial sources or the dilution of the
pollutants in the POTW effluent to lower concentrations due to
the addition of large amounts of non-industrial wastewater.
PRETREATMENT STANDARDS FOR NEW SOURCES
Options for pretreatment of wastewaters from new sources are
based on increasing the effectiveness of end-of-pipe treatment
technologies. All in-plant changes and applicable end-of-pipe
treatment processes have been discussed previously in Sections X
and XI. The options for PSNS are the same as the BAT and NSPS
options discussed in Sections X and XI, respectively.
A description of each option is presented in Sections X and XI,
while a more detailed discussion, including pollutants controlled
by each treatment process is presented in Section VII of the
General Development Document.
Treatment technologies considered for the PSNS options are:
OPTION A
• Preliminary treatment with oil skimming (where required)
• Chemical precipitation and sedimentation
OPTION B
• Preliminary treatment with oil skimming (where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of smelter, electrolytic cells,
and calciner scrubber liquor
146
-------
OPTION C
• Preliminary treatment with oil skimming (where required)
• Chemical precipitation and sedimentation
• In-process flow reduction of smelter, electrolytic cells,
and calciner scrubber liquor
• Multimedia filtration
PSNS OPTION SELECTION
We are proposing PSNS equal to NSPS and BAT for this subcategory.
It is necessary to propose PSNS to prevent pass-through of
arsenic, lead, mercury, silver, and zinc. These toxic pollutants
are removed by a well-operated POTW at an average of 62 percent,
while BAT technology removes approximately 93 percent.
The technology basis for PSNS thus is chemical precipitation and
sedimentation, oil skimming, wastewater flow reduction and
filtration (Option C) . Flow reduction is based on 90 percent
recycle of scrubber effluent that is the flow basis of BAT.
We believe that the proposed PSNS are achievable, and that they
are not a barrier to entry of new plants into this subcategory.
REGULATED POLLUTANT PARAMETERS
Pollutants selected for limitation, in accordance with the
rationale of Sections VI and X, are identical to those selected
for limitation for BAT. It is necessary to propose PSNS to
prevent the pass-through of arsenic, lead, mercury, silver, and
zinc.
PRETREATMENT STANDARDS
Pretreatment standards are based on the treatable concentrations
from the selected treatment technology, (Option C), and the
discharge rates determined in Sections X and XI for BAT and NSPS,
respectively. These discharge rates are presented in Table
XII-1. A mass of pollutant per mass of product (mg/troy ounce or
mg/kilogram) allocation is given for each subdivision within the
subcategory. This pollutant allocation is based on the product
of the treatable concentration from the proposed treatment (mg/1)
and the production normalized wastewater discharge rate (1/troy
ounce or 1/kkg). The achievable treatment concentrations for BAT
are identical to those for PSNS. These concentrations are listed
in Tables VII-19 of the General Development Document. PSNS are
presented in Table XII-2.
147
-------
X
cu
43
cd
H
PS
O
W
O
PS pq
O 3
fe cn
•cn
W
H
^
W
O
CJ
PS
W
33
O
cn
3
H
W
W
H
< cn
W O
H M
cn CJ
< W
cn
z
cn
P-I
PH
r-l
CU
^
rH
•H
CO
TJ
c3
T3
rH
P-I
J5
rVl
O
00
M-f
0
(V
O T3
C CU
3 4J
O rH
W
CU
4J
CO
cd
ex
V-i
•H
cd
4J
CU
3 rH
O
Vj t.
CU 4-1
4J £
rH 0
CU CJ
8
"O
CU
o
0
T3
CU
VH
p
CU
^
1— 1
•H
CO
MH C
0 0
•H
CU 4-1
O 3
C rH
3 O
O co
s^ C
O -H
r-l
4-1
,—
r—
•
O
^>
•
o
c
o
•H
4-1
CJ
rj
"O
CU
V-i
c
CU O
T3 T-l
•H 4J
VH 3
O rH
rH O
43 co
o
4J
t 1 P)2
CU CU
> tx
rH CO
•r-l
cn
TJ
CU
c
•r-l
V4-f
CU
VH
•o >»
rH rH
0 rH
oo cd
o
MH -H
O 4J
>•>
CU rH
o o
C V-i
3 4-1
0 CJ
CU
r^*\ rH
O
cn
CM
•
m
oo
•
Oi
r—
J_l
•iH
cd
4-)
CU
[5
rH
co O
rH V-I
rH 4J
cu c
0 o
o
o
•rH £.;
4J 0
rH 4_}
o 3
S-i i— 1
4J rH
0 0
cu ex
rH
W
1
0
cu
I— 1
cu
c
•iH
V-i
cu
r> "O
rH CU
•H O
CO 3
MH O
0 r4
(X
CU
o cu
{3 J-1
3 r»»
OrH
O
r^*l r4
0 4J
^j
4->
cn
,_
o
•
o
in
o
o
rH
o
V-i
4-1
c c
0 0
•H CJ
4J
cd C
V-i 0
cd ft
CU 3
V< rH
CXrH
o
cu ex
4-)
(x, V-i
rH -H
o cd
V-i
4J 4J
CJ CU
cu £
I— 1
M
CO
rH
cd
4-)
CO
r*S
V-i
CJ
V-i
0)
^
rH
•r-l
CO
14-4
O
cu
CJ
3 cu
co
r*** Cd
O £
V-i
4J
00
o
•
o
o\
CN
•
O
V-i
cu
4_)
cd
5
r!
co
cd
5
i— i
cd
4-1
CO
r*%
V-i
0
V-i
cu
^
rH
•r-l
cn
co
0)
B
•r-l
rH
CO
rQ
rH
O
00
M-(
o
cu
o
C -o
3 cu
043
CO
r^» ^
O IS
M
4J
vO
O
•
r—
O
•
•4-
T3
C
cd
43
co
cd
|5
•o
•H
0
cd cu
co
CO C
CU -H
B VH
•H
rH V-I
CO
TJ cd
rH 5
0
o
T3
CU
CO
C
cu
T3
C
0
O
>>,
V-i
3
CJ
V-i
cu
B
14-1
0
oo
v{
-M
CM
T—
CO
A
m
o
0
o
CN
CM
f3
0
•i-l
, 4->
0
rH
rH
O
CX
V-I
•H
cd
4-1
CU
|5
rH
M 0
CU V-I
C 4J
•H C
0 0
rH 0
cd
CO
•o
CU
CO
C
cu
'O
c
o
CJ
r*S
V-i
j3
O
V-i
cu
B
m
o
00
*
0
vn
vO
••
*j
o
o
^
rC
,—
V-4
0>
4J
cd
43
CJ
C
CU
d
rr
cu
C
•rH
0
rH
cd
T3
CU
CO
C
CU
T3
C
0
CJ
r*~>
V4
rj
O
V-I
CU
B
<4H
O
00
•*
VO
CJ>
0
*
T—
o
m
^
j CU
CJ 4J
cd cd
4-) 3
CO
00
V-i C
CU T-l
C r~ '
•rH 0
0 0
rH 0
cd
O
rrj
CU
CO
C
cu
TJ
C
o
CJ
r*S
VH
3
CJ
VH
CU
B
M-l
O
00
r^*i
^
vO
>^-
UD
»
cn
o
o
00
cn
^~
c
St
o
T)
15
O
rH
43
V-i
CU
co
C
cu
TJ
C
O
O
*o
CU
CO
C
cu
TJ
C
0
CJ
r*%
VH
3
CJ
VH
CU
B
MH
0
00
Jbc£
•*
0
r^
cn
0
0
£>
oo
148
-------
Table XII-2
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(a) Smelter Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold and silver smelted
Arsenic 1.807 0.806
Lead 0.364 0.169
Mercury 0.195 0.078
Silver 0.377 0.156
Zinc 1.326 0.546
(b) Silver Chloride Reduction Spent Solution
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver reduced
0.556
0.112
0.060
0.116
0.408
in solution
0.248
0.052
0.024
0.048
0.168
(c) Electrolytic Cells Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold refined electrolytically
Arsenic 27.520 12.280
Lead 5.544 2.574
Mercury 2.970 1.188
Silver 5.742 2.376
Zinc 20.200 8.316
149
-------
Table XII-2 (Continued)
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(d) Electrolyte Preparation Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver in electrolyte produced
Arsenic 0.070 0.031
Lead 0.014 0.007
Mercury 0.008 0.003
Silver 0.015 0.006
Zinc 0.051 0.021
(e) Silver Crystals Wash Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of silver crystals washed
Arsenic 0.403 0.180
Lead 0.081 0.038
Mercury 0.044 0.017
Silver 0.084 0.035
Zinc 0.296 0.122
(f) Gold Slimes Acid Wash and Water Rinse
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/troy ounce of gold slimes washed
Arsenic 5.560 2.480
Lead 1.120 0.520
Mercury 0.600 0.240
Silver 1.160 0.480
Zinc 4.080 1.680
150
-------
Table XII-2 (Continued)
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(g) Calciner Wet Air Pollution Control
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 30.580 13.640
Lead 6.160 2.860
Mercury 3.300 1.320
Silver 6.380 2.640
Zinc 22.440 9.240
(h) Calcine Quench Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 24.470 10.910
Lead 4.928 2.288
Mercury 2.640 1.056
Silver 5.104 2.112
Zinc 17.950 7.392
(i) Calciner Stack Gas Contact Cooling Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg'(Ib/million Ibs) of mercury condensed
Arsenic 5.769 2.573
Lead 1. 162 0.540
Mercury 0.623 0.249
Silver 1.204 0.498
Zinc 4.233 1.743
151
-------
Table XII-2 (Continued)
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY
(j) Condenser Slowdown
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 19.180 8.556
Lead 3.864 1.794
Mercury 2.070 0.828
Silver 4.002 1.656
Zinc 14.080 5.796
(k) Mercury Cleaning Bath Water
Pollutant or Maximum for Maximum for
Pollutant Property Any One Day Monthly Average
mg/kg (Ib/million Ibs) of mercury condensed
Arsenic 1.946 0.868
Lead 0.392 0.182
Mercury 0.210 0.084
Silver 0.406 0.168
Zinc 1.428 0.588
152
-------
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
SECTION XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
EPA is not proposing best conventional pollutant control
technology (BCT) for the primary precious metals and mercury
subcategory at this time.
153
------- |