Group I. Phase II
Development Document for Interim
Final Effuent Limitations Guidelines
and
Proposed New Source Performance
Standards for the
PRIMARY COPPER SMELTING
SUBCATEGORY AND THE PRIMARY
COPPER REFINING SUBCATEGORY
OF THE COPPER
Segment of the
NONFERROUS METALS
MANUFACTURING
Point Source Category
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
FEBRUARY 1975
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$•
*
V
I,. -.^
% •
ERRATA PAGE
Primary Copper Development Document
1) pp 6, 7, 8, 10, 170, 171, 180, 181, 186,
change all pH ranges to read "pH ...
Within the range 6.0 to 9.0".
2) Pg 95, 3rd paragraph, last sentence, delete
"of the discharge" and replace with "during
liming and settling".
-------
DEVELOPMENT DOCUMENT
for
PROPOSED EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for -the
PRIMARY COPPER SMELTING
SUECATEGORY
and -the
PRIMARY COPPER REFINING
SUBCATEGORY
of the
COPPER SEGMENT
of the
NONFERROUS METALS MANUFACTURING
PCINT SOURCE CATEGORY
Russell E. Train
Admin i str ator
James L. Agee
Assistant Administrator for Water
and Hazardous Materials
Allen Cywin
Director, Effluent Guidelines Division
George s. Thompson, Jr.
Project Officer
November 1974
Effluent Guidelines Division
Office of water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
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-------
ABSTRACT
This document: presents the findings of an extensive study of
the primary copper industry by the Environmental Protection
Agency for the purpose of developing effluent limitations
guidelines and standards of performance, to implement
Sections 304, 306, and 307 of the Federal Water Pollution
Control Act, as amended.
Effluent limitations guidelines contained herein set forth
the degree of effluent reduction attainable through the
application of the best practicable control technology
currently available and the application of the best
available technology economically achievable, which must be
achieved by existing point sources by July 1, 1977, and July
1, 1983, respectively. The standards of performance for new
sources contained herein set forth the degree of effluent
reduction attainable through the application of the best
available demonstrated control technology, processes,
operating methods, or other alternatives.
The development of data and recommendations in this document
relates the waste water generated by the primary copper
smelting subcategory and the primary copper refining
subcategory to the production of primary copper at those
facilities defined by these two subcategories.
Supporting data and rationale for development of the
proposed effluent limitations guidelines and standards of
performance are contained in this report.
111
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CONTENTS
Section
I CONCLUSIONS
II RECOMMENDATIONS
Effluent Limitations Guidelines Based
on the Best Practicable Control
Technology Currently Available 5
Effluent Limitations Guidelines Based
on Best Available Technology
Economically Achievable 9
New Source Performance Standards 10
III INTRODUCTION 11
Purpose and Authority 11
Methods Used in the Development of
Effluent Limitations Guidelines and
Standards of Performance 11
General Description of the Primary
Copper Industry 14
IV INDUSTRY CATEGORIZATION 21
Introduction 21
Objectives of Categorization 21
Factors Considered 21
V WASTE CHARACTERIZATION 57
Introduction 57
Sources of Waste Water 57
Effluent Loadings 71
VI SELECTION OF POLLUTANT PARAMETERS 93
Introduction 93
Rationale for the Selection of
Pollutant Parameters 93
Rationale for Rejection of Other
Waste Water Constituents as
Pollutant Parameters 104
VII CONTROL AND TREATMENT TECHNOLOGY HJ
Introduction 111
Control Technology 112
Treatment Technology 132
VIII COSTS, ENERGY, AND NONWATER QUALITY
ASPECTS 151
Introduction 151
Basis for Cost Estimation 151
v
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CONTENTS (continued)
Section Page
Economics of Present Control and
Treatment Practices 151
Economics of Additional Control and
Treatment Practices 155
Nonwater Quality Aspects 164
IX BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE—EFFLUENT
LIMITATIONS GUIDELINES 167
Introduction 167
Industry Category and Waste
Water Streams 168
Waste Water From the Primary
Copper Smelting Subcategory 169
Waste Water From the Primary
Copper Refining Subcategory 179
X BEST AVAILABLE TECHNOLOGY ECONOMICALLY
ACHIEVABLE—EFFLUENT LIMITATIONS GUIDELINES 185
Waste Water From the Primary
Copper Smelting Subcategory 185
Waste Water From the Primary
Copper Refining Subcategory 185
XI NEW SOURCE PERFORMANCE STANDARDS 189
XII ACKNOWLEDGMENTS 191
XIII REFERENCES 193
Bibliography 195
XIV GLOSSARY 199
VI
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FIGURES
Number Titlg
1 United states Producer's Average Annual
Prices of Electrolytic Copper 18
2 Location of Primary Copper Smelters in the
United States 22
3 Primary Copper Smelting Processes and Equipment 26
4 Location of Copper Refineries in the United States 33
5 Generalized Flow Diagram of Electrolytic
Copper Refinery 38
6 Flowsheet of Selenium-Tellurium Recovery
Process 43
7 Primary Copper Industry Operating Characteristics 47
8 Generalized Schematic of Waste Effluents
from the Electrolytic Refining of Copper 64
9 Generalized Schematic of Waste Effluents
From Byproduct Processing
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TABLES
Title Page
United States Copper Smelter Production
from Domestic Ores 15
2 Production of Refined Copper by United
States Refineries 16
3 United states Deliveries, Imports, and
Exports of Refined Copper 17
4 Characteristics of Primary Copper Smelters 23
5 Typical Analyses of Blister Copper 30
6 Characteristics of Primary Copper
Electrolytic Refineries 34
7 General Range-Analysis of Anode, Electrolyte,
Refined Copper, and Anode Slime 39
8 Copper Minerals Important in United states
Production 48
9 Examples of Raw Waste Pollutant concentrations
From Primary Copper Slag Granulation Operations 59
10 Analysis of Raw Waste pollutant Concentrations
From Primary Copper Acid Plant Blowdown 61
11 Analysis of Raw Waste water Used to Cool
Cast Copper Anodes and Refinery shapes 62
12 Example of Raw Waste Effluent From
Arsenic Plant Washdown 72
13- Raw Waste Characterization: Slag
Granulation Water 74
14 Raw Waste Characterization: Acid Plant
Blowdown 75
15 Raw Waste Characterization: Contact
Cooling water 76
16 Waste Effluents From Plant No. 115
(Outfall No, 001) 78
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TABLES (continued)
Number Title
17 Waste Effluents From Plant No. 115
(Outfall No. 002) 79
18 Waste Effluents From Plant No. 116
(Outfall No. 001) 80
19 Waste Effluents From Plant No. 116
(Outfall No. 005) 81
20 Waste Effluents From Plant No. 117
(Outfall No. 004) 82
21 Waste Effluents From Plant No. 118
(Outfall No. 002) 83
22 Waste Effluents From Plant No. 118*
(Outfall No. 005) 84
23 Waste Effluents From Plant No. 119
(Outfall No. 001) 85
24 Waste Effluents From Plant No. 121
(Outfall No. 002) 86
25 Waste Effluents From Plant No. 121
(Outfall No. 005) 87
26 Waste Effluents From Plant No. 121
(Outfall No. 008) 88
27 Waste Effluents From Plant No. 102
(Outfall No. 003) 89
28 Waste Effluents From Plant No. 102
(Outfall No. 004) 90
29 Waste Effluents From Plant No. 110
(Cutfall No. 004) 91
30 Summary of Effluent Loadings of Selected
Constituents From Selected United States
Copper Refineries 92
IX
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TABLES (continued)
Number Title Page
31 Slag Granulation Water Control and
Treatment Practices
32 Acid Plant Slowdown Control and
Treatment Practices
33 Contact Cooling Water Control and
.
Treatment Practices
34 Electrolytic Refinery Waste Water Control
and Treatment Practices 125
35 Concentrations of Selected Constituents
of Acid Plant Effluent Streams Before and
After Liming 138
36 Waste Effluent Concentrations After Liming
and Settling Combined Waste Streams 142
37 Expected Values of Effluent Concentrations
From New Treatment Facility (Plant 110) 144
38 Additional Control and Treatment Costs
39 Conversion Table 213
x
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SECTION I
CONCLUSIONS
The nonferrous metals manufacturing point source category
has been divided into the following subcategories:
(1) Bauxite refining subcategory
(2) Primary aluminum subcategory
(3) Secondary aluminum subcategory
(4) Primary copper smelting sutcategory
(5) Primary copper refining subcategory
(6) Secondary copper subcategory
(7) Primary lead subcategory
(8) Primary zinc subcategory
Each subcategory has been found to be distinctly different
from the standpoints of processes employed, products
produced, and process waste waters generated, as well as
other less significant factors. Effluent limitations and
standards of performance were promulgated on March 26, 1974,
for the first three subcategories listed above. Development
documents supporting the rationale for these regulations
have been published. This development document presents the
rationale for establishing proposed effluent limitations
guidelines and standards of performance for the primary
copper smelting and primary copper refining subcategories.
Consideration of factors, such as manufacturing processes
employed, raw materials used, products produced, wastes
generated, plant size and age, plant location and air
pollution control equipment used, supports the
categorization of the primary copper industry into two
separate subcategories. The first subcategory, the primary
copper smelting subcategory includes all primary copper
smelting facilities and their on-site primary copper
refineries, if such operations exist on-site. The second
subcategory for this industry, the primary copper refining
subcategory, includes all primary copper refineries which
are not operated on-site with a primary copper smelter.
Another very important reason for this industrial
differentiation is presented in Section VII of the document,
in that available routes of control technology are much more
numerous for the smelting facilities than for the primary
refineries not located on-site with a smelter. Disposal
sources for generated process waste water by means of
recycle and reuse are available at smelters integrated with
mining and/or milling operations. Due to the high heat
generation of the primary copper pyrometallurgical
-------
processing operations, thermal consumption of process waste
water is also practiced at primary smelters.
One conclusion developed by this document was that no
discharge of process waste water pollutants to navigable
waters could be achieved by those facilities defined under
the primary copper smelting subcategory by July lr 1977, by
the application of the best practicable control technology
currently available. This technology includes recycle and
reuse of process waste water after, as needed,
neutralization and settling*
Due to the differences in the two sutcategories, a discharge
provision of process waste water pollutants, the volume of
which was defined by the average of the best practices
within the industry, was granted with the best practicable
control technology currently available being neutralization
and settling. This provision is allowed for only those
primary copper refineries not located on-site with a primary
copper smelter and which are geographically located in areas
of net rainfall. Those remaining primary copper refineries
defined by this subcategory, which are geographically
located in areas of net evaporation, must comply to a no
discharge of process waste water pollutant limitation, based
upon recycle, reuse, and solar evaporation.
The best available technology economically achievable for
the primary copper smelting sutcategory, as well as those
refining facilities of the primary copper refining
subcategory which are geographically located in areas of net
evaporation, is identical to the best practicable control
technology currently available proposed for these same
facilities. The best available technology economically
achievable for these remaining primary refineries of the
primary copper refining subcategory geographically located
in areas of net rainfall is a further reduction of process
waste water volumetric flow rate, through additional recycle
and reuse, and neutralization and settling prior to
discharge.
The recommended standards of performance for both
subcategories, based upon the best available demonstrated
control technology, processes, operating methods, or other
alternatives, are identical to the proposed effluent
limitations derived on the basis of the best available
technology economically achievable.
To alleviate current or potential problems associated with
storm water runoff, special discharge provisions for this
source of process waste water are proposed on a 30-day basis
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for all facilities subjected to no discharge of process
waste water pollutants to navigable water limitations.
It has been estimated that for the existing plants in the
primary copper smelting subcategory to achieve the levels of
control of process waste water pollutants, as recommended by
this development document, would require a total capital
cost and annual operating cost of $1,212,000 and $284,000,
respectively.
For the existing plants of the primary copper refining
subcategory to achieve the levels of control of process
waste water pollutants recommended for July 1, 1977f the
capital costs required will approximate $334,000 and the
annual operating costs required will be about $118,000.
Incremental control and/or treatment costs of approximately
$1,581,000 capital and $805,000 annual operating will be
required of three plants to achieve the further reductions
in discharge of process waste water pollutants recommended
for the best available technology effluent limitations of
1983. Therefore, the total estimated capital and annual
operating costs for the primary copper refining subcategory
are $1,915,000 and $923,000, respectively.
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SECTION II
RECOMMENDATIONS
Effluent_Limitations Guidelines Based on
Best Practicable Control_TechnQlogy
Currently Available
Primary Copper Smelting Subcategory
The following proposed limitations establish the quantity or
quality of pollutants or pollutant properties, which may be
discharged by a point source subject to this subcategory
after application of the best practicable control technology
currently available.
Subject to the provisions of the following paragraphs, there
shall be no discharge of process waste water pollutants into
navigable waters.
A process waste water impoundment which is designed,
constructed and operated so as to contain the
precipitation from the 10 year, 24 hour rainfall event
as established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located may discharge that
volume of process waste water which is equivalent to the
volume of precipitation that falls within the
impoundment in excess of that attributable to the 10
year, 24 hour rainfall event, when such event occurs.
During any calendar month there may be discharged from a
process waste water impoundment either a volume of
process waste water equal to the difference between the
precipitation for that month that falls within the
impoundment and the evaporation within the impoundment
for that month, or, if greater, a volume of process
waste water equal to the difference between the mean
precipitation for that month that falls within the
impoundment and the mean evaporation for that month as
established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located (or as otherwise
determined if no monthly data have been established by
the National Climatic Center).
Any process waste water discharged pursuant to the above
paragraph shall ccmply with each of the following
requirements:
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Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units fmcf/l>
TSS 50 25
As 20 10
Cu 0.5 0.25
Pb 1.0 0.5
Cd 1.0 0.5
Se 10 5
Zn 10 5
pH Within the range 7.0 to 10.5
English units (ppm)
TSS
As
Cu
Pb
Cd
Se
Zn
PH
50
20
0.5
1.0
1.0
10
10
Within the ranqe
25
10
0.25
0.5
0.5
5
5
7.0 to 10.5
When commingled waters are contained in the impoundment area,
the volume of water allowably discharged to navigable waters
due to the conditions of the above paragraphs will equal the
volume calculated on the basis of the ratio of process waste
water volume and total impoundment volume.
Primary Copper Refining Subcateqory
Primary Copper Refineries Geographically Located in Areas of
Net Evaporation. The following proposed limitations
establish the quantity or quality of pollutants or pollutant
properties, which may be discharged by a point source
subject to this subcategory after application of the best
practicable control technology currently available.
Subject to the provisions of the following paragraphs, there
shall be no discharge of process waste water pollutants into
navigable water.
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A process waste water impoundment which is designed,
constructed and operated so as to contain the
precipitation from the 10 year, 24 hour rainfall event
as established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located may discharge that
volume o£ process waste water which is equivalent to the
volume of precipitation that falls within the
impoundment in excess of that attributable to the 10
year, 24 hour rainfall event, when such event occurs.
During any calendar month there may be discharged from a
process waste water impoundment either a volume of
process waste water equal to the difference between the
precipitation for that month that falls within the
impoundment and the evaporation within the impoundment
for that month, or, if greater, a volume of process
waste water equal to the difference between the mean
precipitation for that month that falls within the
impoundment and the mean evaporation for that month as
established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located (or as otherwise
determined if no monthly data have been established by
the National Climatic Center).
Any process waste water discharged pursuant to the above
paragraph shall comply with each of the following
requirements:
Eff1u§n t_l im i t ations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
.Metric units, (mg/1) ,
TSS 50 25
As 20 10
Cu 0.5 0.25
Se 10 5
Zn 10 5
Oil and grease 20 10
pH Within the range 7.0 to 10.5
English units £jo]2m)_
TSS 50 25
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As 20 10
Cu 0.5 0.25
Se 10 5
Zn 10 5
Oil and grease 20 1C
pH Within the range 7.0 to 10.5
When commingled waters are contained in the impoundment area,
the volume of water allowably discharged to navigable waters
due to the conditions of the above paragraphs will equal the
volume calculated on the basis of the ratio of process waste
water volume and total impoundment volume.
Primary Copper Refineries Geographically Located in Areas of
Net RainfallA The proposed limitations based on the
application of the best practicable control technology
currently available for primary copper refineries
geographically located in areas of net rainfall are:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units (kilograms per 1,000 kg
of product)
TSS 0.10 0.05
As 0.04 0.02
Zn 0.02 0.01
Se 0.02 0.01
Cu 0.001 0.0005
Oil anc grease 0.04 0.02
pH Within the range 7.0 bo 10.0
English units (pounds per 1,000 Ib
of product)
TSS 0.10 0.05
As 0.04 0.02
Zn 0.02 0.01
Se 0.02 0.01
Cu 0.001 0.0005
Oil and grease 0.04 0.02
P.H Within the range 7.0 to 10.Q
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The above limitations and their rationale are discussed in
detail in Section IX.
Effluent Limitations Guidelines Based on
Best. Available Technology Economically Achievable
Primary Copper Smelting Subcategory
The best available technology economically achievable for
the primary copper smelting subcategory is identical to the
best practicable control technology currently available.
The corresponding effluent limitation is no discharge of
process waste water pollutants to navigable waters. Other
provisions for this subcategory are identical to those
listed above under effluent limitations guidelines based on
best practicable control -technology currently available for
this same sutcategory.
Primary Copper Reflning Subcategpry
Primary Copper Refineries Geographically Located in Areas__ of
Net Evaporation. The best available technology economically
achievable for these refineries, not operated on-site with a
primary smelter and located in geographical areas of net
evaporation, is identical to the best practicable control
technology currently available. The corresponding effluent
limitation is no discharge of process waste water pollutants
to navigable waters. Other provisions for this sufccategory
are identical to those listed above under effluent
limitations guidelines based on best practicable control
technology currently available for this same subcategory.
Primary Copper Refineries Geographically Located in Areas Of
Net Rainfall. The following proposed limitations establish
the quantity or quality of pollutants or pollutant
properties, which may be discharged by a point source
subject to this sufccategory after application of the best
available technology economically achievable:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units (kilograms per 1,000 kg
of product)
-------
TSS 0.01 0.005
As 0.004 0.002
Zn 0.002 0.001
Se 0.002 0.001
Cu 0.0001 0.00005
Oil and grease 0.004 0.002
pH Within the range 7.0 to 10-0
English units (pounds per 1,000 Ib
of product)
Oil and grease
pH
0.01 0.005
0.004 0.002
0.002 0.001
0.002 0.001
0.0001 0.00005
0.004 0.002
Within the range 7.0 to 10..0
The above limitations and their rationale are discussed in
Section X.
New_Source Performance Standards
The best available demonstrated control technology,
processes, operating methods, or other alternatives are
identical to the best available technology economically
achievable. The corresponding standard of performance is
identical to the effluent limitations guidelines established
from usage of the best available technology economically
achievable.
10
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SECTION III
INTRODUCTION
Purpose and,Authority
Section 301 (b) of the Act requires the achievement by not
later than July 1, 1977, of effluent limitations for point
sources/ other than publicly owned treatment works, which
are based on the application of the best practicable control
technology currently available as defined by the
Administrator pursuant to Section 304 (b) of the Act.
Section 301 (b) also requires the acievement by not later
than July 1, 1983, of effluent limitations for point
sources, ether than publicly cwned treatment works, which
are based on the application of the best available
technology economically achievable which will result in
reasonable further progress toward the goal of eliminating
the discharge of all pollutants, as determined in accordance
with regulations issued by the Administrator pursuant to
Section 304 (b) to the Act.
Section 306 of the Act requires the achievement by new
sources of a Federal standard cf performance providing for
the control of the discharge of pollutants which reflects
the greatest degree of effluent reduction which the
Administrator determines to be achievable through the
application of the best available demonstrated control
technology, processes, operating methods, or other
alternatives, including, where practicable, a standard
permitting no discharge of pollutants.
Section 304(b) of the Act requires the Administrator to
publish within one year of enactment of the Act, regulations
providing guidelines for effluent limitations setting forth
the degree of effluent reduction attainable through the
application of the best practicable control technology
currently available and the degree of effluent reduction
attainable through the application of the best control
measures and practices achievable, including treatment
techniques, process and procedure innovations, operation
methods and other alternatives. The proposed regulations
contained herein set forth effluent limitations guidelines
pursuant to Section 304 (b) of the Act for the primary copper
smelting sufccategory of the nonferrous metals category.
Methods Used in the Development of Effluent
Limitations guidelines and Standards of Performance
The effluent limitations guidelines and standards of
11
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performance recommended in this document for the primary
copper industry, were developed by analyzing information on
the industry and its current water quality management
practices, as well as the practices in related industries.
Initially, an extensive literature search was made of
statistical abstracts, monographs, and journal articles (see
reference list) in order to assemble data on the companies
engaged in the primary copper industry. From this
information an inventory was compiled for each facility
covering location, age, climate, number of employees,
operations conducted, production figures, air pollution
control systems employed, and future plans. This inventory
provided an overview upon which later data acquisitions
could be built and from which the need for industry
subcategorization could be assessed.
There are 22 plants or properties in the United States
presently engaged in the primary smelting and refining of
copper. One other primary copper smelter is currently under
construction. A representative of each of these plants was
contacted by telephone or letter to acquire information on
production operations and water treatment methods. Several
state water pollution control offices and EPA regional
offices contributed information on the primary copper
facilities under their jurisdiction.
Plant visits were made to sites encompassing the following:
7 smelters;
6 electrolytic refineries;
1 fire refinery;
4 acid plant operations,
plus one under construction.
The sites selected for visits represented a variety of
climates, industry processing practices, ore types, and
water quality management methods.
Additional data for plant sites were obtained from the Corps
of Engineers Peririts to Discharge under the Refuse Act
Permit Program (RAPP). These included, in varying degrees
of detail, composition, temperature, and volume of intake
and effluent water, plus a general description of waste
water treatment. Some water analysis data were also
provided in questionnaires completed by several companies.
Four plant sites were visited to sairple and analyze selected
internal and outfall streams. The sites were selected in
12
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order to obtain the widest variety of streams at an instal-
lation, to develop specific information regarding unit
operations and waste characterization, to verify the
effluent data, and to determine the effect of waste water
treatment. The samples taken included one or more of the
following:
Inlet water.
Slag granulation water (inlet and
effluent),
Anode casting cooling water (inlet and
effluent),
Wirebar cooling water (inlet and
effluent),
Acid plant slurry (before and after
treatment),
Arsenic plant washdown.
Molybdenum plant scrubber effluent.
Silver recovery effluent.
Electrolyte purification effluent.
Powerpiant boiler blowdown.
Final outfall.
The data obtained from the literature and the field were
analyzed to identify the sources and volumes of waste water
produced, and the quantities of constituents contained in
the discharge. On the basis of this analysis, the pollutant
parameters of waste water subject to effluent limitations
and standards of performance were identified.
Data gathered on control and treatment technologies
currently in use or under test were supplemented by
information covering control technologies from other
industries, which might be applicable to the treatment and
control of waste water from the primary copper industry.
Consideration was given to both inplant and end-of-process
technologies and to applications to the effluent from the
various production operations. For each of the control or
treatment technology candidates, the resultant waste water
constituents were determined; the limitations and problems
associated with each technology were considered.
Installation and operating cost estimates for application of
the technologies were calculated. Environmental impacts,
which might affect air quality, solid waste disposal, and
ambient noise levels were assessed.
All of the information that had been developed was evaluated
in order to determine what levels of technology constitute
the best practicable control technology currently available.
13
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-the best available -technology economically achievable, and
the best available derrcnstrated control technology.
General Description of the Primary Copper Industry
One category of the industry encompassing the primary
smelting and refining of nonferrous metals (Standard
Industrial Classification Number 333) is the primary
smelting and refining of copper (SIC Number 3331). SIC
Number 3331 describes those establishments primarily engaged
in smelting copper from the ore, and in refining copper by
electrolytic or other processes. Operations such as the
mining and benefication of copper ore, as well as the
rolling, drawing, and extruding of copper, are classified
under other SIC's and are not a subject of this development
document. This document presents recommended effluent
limitations guidelines and standards of performance for this
industry. Mining and beneficiation, are excluded from the
recommendations derived in this document.
History and Industry Statistics
Until 1850 the United States contributed less than 0.5
percent of the world's output of copper. In the latter half
of the 19th century, copper production in the United States
increased rapidly, and by the first quarter of the 20th
century, this country was producing 57 percent of the
world's copper.
Demand for copper attained high levels as a result of
industrial and residential electrification, as well as the
increasing production of automobiles and electrical ap-
pliances. Copper consumption reached peaks during world
Wars I and II. In later years this demand slackened as
electrification was accomplished nationwide, and aluminum
had become a competitor for the electrical market. As
demonstrated by Tables 1,2, and 3, there have been no long
term trends in the production or use cf copper in the United
Stares during the last 10 to 15 years. Primary copper
production, secondary copper production, and imports and
exports have all fluctuated. The price of copper during
this same period has increased (Figure 1), showing a gain of
over 60 percent between 1957 and 1972.
Originally, the native copper mines of Michigan's upper
peninsula produced practically all of the copper in the
United States. After 1887, Montana assumed the lead as the
Butte copper district was developed. However, by 1907
Arizona had become the major producer in the country, a
14
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TABLE 1 . UNITED STATES COPPER SMELTER
PRODUCTION FROM DOMESTIC
ORES
Year
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Annual
kkg
827,000
844,000
841,000
856,000
757,000
914,000
1, 014,000
981, 000
901,000
725, 000
1,037,000
1, 055, 000
1, 163,000
1, 141,000
1, 180,000
1,273,000
1,297,000
763, 000
1,120,000
1,404, 000
1,456,000
1,334, 000
1,542,000
Production
Short Tons
911,000
931,000
927,000
943,000
834, 000
1, 007,000
1, 118, 000
1,081,000
993,000
799,000
1, 143, 000
1, 162, 000
1,282, 000
1,258,000
1,301, 000
1,403,000
1,430, 000
841,000
1,235,000
1,547, 000
1,605,000
1,471,000
1,700, 000
(a) Preliminary.
Source: Metal Statistics. 1973 (from Bureau of
Mines).
15
-------
TABLE 2.
PRODUCTION OF REFINED COPPER BY UNITED STATES REFINERIES
Production
Total
Year
1956
1957
1958
1959
I960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
Source ;
kkg
1,565,
1,549,
1,383,
1,207,
1,639,
1,628,
1,715,
1,708,
1,804,
1,991,
2,047,
1,371,
1,645,
2,030,
2,090,
1,804,
Metal Statistics,
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
1973 (data
Short Tons
1,725, 000
1,708, 000
1, 525,000
1,331,000
1, 808, 000
1,795,000
1,891, 000
1, 884, 000
1,988,000
2, 195, 000
2,257, 000
1, 512, 000
1,814,000
2,238,000
2, 305, 000
1,989,000
Secondary
kkg
216, 000
199, 000
189, 000
213,000
236,000
222, 000
228, 000
245, 000
284,000
381, 000
449,000
329,000
338,000
401, 000
447,000
336,000
compiled by American Bureau of Metal
Short
238,
219,
208,
235,
260,
245,
251,
271,
314,
420,
495,
362,
373,
443,
493,
371,
Statistics).
Tons
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
Primary
kkg
1,349,
1,350,
1,194,
994,
1,403,
1,406,
1,487,
1,463,
1,520,
1,610,
1,598,
1,042,
1,307,
1,629,
1,643,
1,468,
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
or Virgin
Short
1,487
1,489
1,317
1,096
1, 548
1, 550
1,640
1,613
1,674
1,775
1,762
1, 150
1,441
1,795
Tons
, 000
, 000
,000
, 000
,000
, 000
, 000
, 000
, 000
, 000
, 000
, 000
,000
,000
1,812,000
,1,618
, 000
Primary
Percentage
of Total
86
87
86
82
85
86
87
86
84
81
78
76
79
80
79
81
-------
TABLE 3. UNITED STATES DELIVERIES, IMPORTS, AND EXPORTS OF REFINED COPPER
Refined Copper
Delivered Within U. S. (a>
Year
1964
1965
1966
1967
1968
1969
1970
1971
1972
kkg
1, 526,000
1, 683, 000
2, 031, 000
1,447,000
1, 548, 000
1,736,000
1, 648, 000
1, 597, 000
1,796, 000
Short Tons
1,683,
1,855,
2,240,
1,595,
1,707,
1,914,
1,817,
1,760,
1,980,
000
000
000
000
000
000
000
000
000
Imported^*
kkg
125,
124,
148,
298,
368,
119,
120,
147,
172,
000
000
000
000
000
000
000
000
000
iShort Tons
138,000
137,000
163, 000
329, 000
405, 000
131, 000
132, 000
162, 000
189, 000
Exported
kkg
287,000
295, 000
248, 000
145, 000
218,000
182, 000
201, 000
170, 000
165,000
Short Tons
316, 000
325, 000
273, 000
159, 000
241, 000
200, 000
221, 000
188, 000
181, 000
Accumulated Stocks'0'
kkg
54
48
55
57
51
47
68
101,
'l26,
, 000
, 000
, 000
, 000
, 000
,000
, 000
000
000
Short Tons
60, 000
52, 000
60, 000
63, 000
57, 000
52, 000
75, 000
111, 000
139, 000
(a) Figures cover refined copper in U. S. regardless of origin. Includes copper withdrawn from and delivered TO Government stocks and imports of foreign
copper- Source: Copper Institute, Inc.
(b) Compiled from Bureau of the Census Records.
(c) Figures include refined copper in U. S. regardless of origin- Source: Copper Institute, inc.
Source: Metal Statistics, 1973.
-------
140
1955 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
Year
Figure 1. United States producer's average annual prices of electrolytic copper.
-------
position it still retains. In 1970 Arizona supplied 53
percent of the ore mined in the United States, Utah was
second with 17 percent, followed in descending order by New
Mexico, Montana, Nevada, and Michigan. Approximately 1
percent of the 1970 output was produced by three mines in
eastern United States, one each in North Carolina,
Pennsylvania, and Tennessee.
with the major copper mines centered in the western states,
most of the smelting capacity is in that area. Of the
fifteen smelters operating in 1972, only two were east of
the Mississippi River. Seven were in Arizona and eight
other states had one each. Only one primary smelter in
Tacoma, Washington, was not located near copper mining
operations.
In the past, the greater part of the electrolytic refining
was done on the middle Atlantic coast. Low cost power,
large nearby markets, and ocean transportation for the
importation of blister copper from foreign countries
combined to produce this pattern. These advantages have now
largely disappeared as the southwestern United States has
become the major supplier of U. S. copper and refining has
moved westward. Thus, there is now a trend for more of the
refining to be done at electrolytic refineries near the
smelters.
Another current trend is the building of facilities to
produce sulfuric acid or elemental sulfur from the sulfur
dioxide created in the smelting process. While the sulfuric
acid can be used in leaching operations or sold to outside
consumers, the principal impetus for collection of the
sulfur dioxide byproduct has been to meet air pollution
regulations requiring a large reduction in atmospheric
sulfur oxide emissions from smelter complexes.
Process
The basic process used by the primary copper industry, as it
currently exists, is pyrcmetallurgical. Copper concentrates
are fed to the primary smelter, which conventionally
produces blister copper after roasting, smelting, and
converting. The blister copper is then normally purified by
fire-refining, a pyrcmetallurgical operation. If additional
purification is required, an electrolytic process is
employed with the final product being cathode copper.
Byproducts, such as gold and silver, which were contaminants
19
-------
of the blister copper, are collected as "slimes" during
electrolytic refining and are subsequently recovered.
As discussed in detail in the next section, the primary
copper industry is composed of primary smelters and
refineries. All of the processes discussed in the preceding
paragraph may occur at one facility; whereas, at another
facility, electrolytic refining may be its only process
operation.
Processes, which will be used fcy new primary copper
facilities, will be both pyrcmetallurgical and
hydrometallurgical. New process equipment for the
pyrometallurgical operations will be of the type that
produces gas streams which are amenable to conventional
sulfur oxide control.
20
-------
SECTION IV
INDUSTRY CATEGORIZATION
This section describes the scope of the primary copper
industry. Included are technical discussions on
manufacturing process , raw materials, products produced,
wastes generated, plant size and age, plant location, and
air pollution control. Possible methods of subcategorizing
this industry into discrete units of separate control and
treatment technology and effluent limitations are also
discussed.
Objectives of Categorization
The objective of industry categorization is to establish
recommended effluent limitations and standards of
performance, which are specific and uniformly applicable to
a given category. Categorization, therefore, involves the
identification and examination of the factors in the
industry, which might effect categorization in terms of the
recommendations tc be developed.
Factors Considered
Manufacturing Process
Copper Smelting. There are 15 currently operating
primary copper smelters in the United States. The
distribution of these 15 facilities is shown in Figure 2.
Eleven of the 15 are integrated smelters, in that they
mostly process their own copper concentrates produced on-
site or in the near vicinity of the smelter. The remaining
four smelters are of the custom type; wherein, copper
concentrates are purchased from other sources and are
blended and processed at the smelter. Table 4 list each of
these primary smelters by name and location. Process
description, products made, plant age, and air pollution
control practices are also tabulated.
All 15 primary copper smelting facilities produce copper by
pyrometallurgical means. As portrayed in Figure 3, two
conventional smelting schemes are used; roasting, smelting,
and converting or sirelting and converting.
21
-------
NJ
NJ
/ EAST NORTH CENTRAL
Primary copper smelter
Figure 2. location of primary7 copper smelters in the United States,
-------
TABLE 4. eHARACTERISTICS OF PRIMARY COPPER SMELTERS
COMPANY/
LOCATION
ASARCO/ El Paso,
Texas
ASARCO/ Hayden,
Arizona
ASARCO/ Tacoma,
Washington
Phelps-Dodge/
Douglas, Arizona
AGE
1887
1912
1890
1904
I/CU)
c
c
c
c
PRODUCTS
Blister Cu:
100,000 T/yr,
Gold, Silver,
H2S04 :
500 T/D
Blister Cu:
180,000 T/yr
(Cap).
Blister Cu:
100,000 T/yr,
Elec. Ref. Cu:
120,000 T/yr,
Gold, Silver,
NiS04, AsoOi
H2S04: 150 T/D
Liquid 502
Blister Cu:
(Shot):
4,100 T/yr,
Fire-Refined Cu:
142,000 T/yr.
Gold, Silver
mOCESS DESCRIPTION
Copper concentrates roasted in multiple-
hearth roasters, calcine to reverbera-
tory furaace (reverb), slag is discardet
on dump, and matte is charged to
converters. Copper is cast into anodes,
Copper concentrates roasted in multiple'
hearth roasters, calcine to reverb,
matte to converters. Copper cast into
anodes.
Copper concentrates roasted in multiple-
hearth roasters, calcine to reverb,
slag to dump, matte to converters,
product blister copper. Electrolytic
refining with approximately 1600 tanks.
Copper concentrates roasted in multiple-
hearth roasters, calcine to reverbs, sla
to dump, matte to converters. Blister
copper tc fire-refining.
AIR POUJUTICN COMTROb
Roaster gases to settling flue.
join reverb gases, then 60
electrostatic precipitator (ESP)
Converter gases to 1973, 500 T/C
double contact acid plant.
All gases to ESP. Converter
gases to 1971, 750 T/D single
contact acid plant.
fill roaster and reverb gases to
ESP (A$203 collected from
roaster gases).
'art of converter gases to
1950, 150 T/D single contact
acid plant; remainder of gases
to DMA facility with concen-
trated SQjif stream to liquid
SOg plant.
U 1 gases to ESP. no S09 control .
1
r\>
U)
Integrated Facility (I), Custctn Facility
-------
TABLE 4. (CONTINUED)
COMPANY/
IflCATICN
Phelps-Dodge/
Morenci , Arizona
Kennecott/
Hayden, Arizona
Cities Service/
Copperhill, Tenn.
Anaconda/
Anaconda, Montana
Kennecott/
Hurley, N.M.
Kennecott/
McGIll,
Nevada
AGE
1942
1958
1971
(last
major
revision)
1903
1938
1908
I/C<1)
I
I
I
I
I
I
PRODUCTS
Fire-Refined Cu:
182,000 T/yr,
Gold, Silver,
H2S04.
Blister Cu:
80,000 T/yr,
(tonnage approx).
Blister Cu:
15,000 T/yr,
Shot Cu, Some
Cu Chemicals,
Fire-Refined Cu:
202,000 T/yr,
H2SOa:
660 T/D.
Blister Cu:
4,000 T/yr,
Fire-Refined Cu:
88,200 T/yr,
Mo
H2S04: 600 T/D
(under const).
Blister Cu:
43,000 T/yr,
Mo.
MCCESS DESCRIPTION
Cooper concentrates to fluid-bed roaster,
calcine to reverb, slag to dump, matte
to converters. Blister copper to fire-
refining.
Cooper concentrates to fluid-bed roaster,
calcine to reverb, slag to dump, matte
to converters, anodes cast.
Copper concentrates to fluid-bed roaster,
calcine to electric furnace, slag water-
quenched, matte to converters.
Copper concentrates dried in multiple-
hearth roasters, fed to reverbs, slag
granulated, matte to converters, blister
copper fire-refined.
Copper concentrates to reverbs (green
feed), slag to dump, matte to converter,
blister copper fire-refined.
Copper concentrates to reverbs (green
feed), slag granulated, matte to con-
verters.
AIR PGLLL/TICN CONTROL
All roaster gases to 1964,
750 T/D single contact add
plant.
All reverb and converter gases
to ESP.
Reverb gases to waste heat
boiler, ESP.
All roaster and converter gase:
to double contact acid plant
(modified single contact).
All gases join pyrite gases,
go to four acid plants, slip-
stream to DMA, concentrated
S02 effluent to liquid S02
plant.
Reverb gases to water spray
and ESP.
Converter gases to 1973,
660 T/D double-contact add
plant.
Reverb gases to ESP.
Converter gases to 1974,
600 T/D double-contact acid
plant.
Reverb and converter gases
treated by waste boilers,
settling flue, ESP, and
multiclones.
-------
TABLE 4. (CONTINUED)
COMPANY/
LOCATION
Kennecott/
Garfield,
Utah
tegma/
Sam Manuel ,
Arizona
Mite Pine/
White Pine,
Michigan
Inspiration/
Miami ,
Arizona
'helps - Dodge/
Ajo,
Arizona
AGE
1900
1955
1953
1911
1917
1/cO)
i
PRODUCTS
Electrolytically-
refined c'u:
260,000 T/yr
Mo, gold, Se,
j Silver,
I
I
I
I
.
-f2S04:1400 T/D.
Electrolytically-
refined cu:
57,000 T/yr.
(200,000 Cap.),
•ire-refined cu:
183,000 T/yr,
•lo, gold, silver
^S04:1500 T/D
(under const.).
!Mstcr CM: 72, 000
T/yr, Fire-re-
fired Cu:70,000
T/vr. Silver
Hectrolytically
refined cu:
75,000 T/yr,
Slister cu:
118,000 T/yr,
to, gold, silver,
Se.
Blister Cu:
55,400 T/yr,
Sold, silver,
rf2S04:700 T/D.
PROCESS DESCRIPTION
Copper concentrates to reverbs (green
feed), slag granualted, matte to con-
verters, blister copper fire-refined,
fire-refined copper electrolytically-
refined to cathode copper.
Copper concentrates to reverbs (green
feed), slag to dump, matte to converter?,
blister copper fire-refined, fire-
refined copper electrolytically-refined.
Copper concentrates to reverbs {green
feed), matte to converters, blister
copper is fire-refined.
)ld: copper concentrates to reverb, mattei
to converters, some blister is
electrolytically refined.
Rew plant: copper concentrates to
electric furnace, si eg to dump, matte to
syphon converters, blister copper flre-
cefined.
Copper concentrates to reverb furnace,
slag to dump, matte to converters,
blister copper produced.
AIR POLLUTION CONTROL
Reverb gases to ESP.
All converter gases to five ack
plants producing 1400 T/D acid.
Reverb gases to ESP.
Converter gases to 1974, 1500
T/D acid plant (under const.)
teverb gases to ESP and balloon
flue.
)ld plant: Reverb gases to
waste heat boiler and flue.
Converter gases to balloon
flue.
\lT gases to new sTngle contact
acid plant.
U1 gases to 1973 single contact
700 T/P acid plant, reverb
gases subjected to DMA.
-------
g
I
EH
ea
Copper Concentrates
Multiple-Hearth
Roasting (4 Plants1
Fluid-Bed
toasting (3 Plants)
Calcine
I
Reverb Furnace
(6 Plants)
Electric Furnace
(1 Plant)
1
Waste
Slag
Matte
Converters
(7 Plants)
Blister Copper
Green Feed
(8 Plants)
Reverb Furnace
(7 + i"oia"PlantSj
Electric Furnace
Unnew" Plant)
(1)
Slag
Matte
i
Converters
(8 Plants)
Blister Copper
Figure 3. Prirai^ copper smelting processes and equipment.
(1)nold" and "new" plants are parallel operations at same site.
26
-------
and Converting. Generally, primary
copper facilities which process numerous copper concentrates
from various sources use this scheme. As shown by Table 4,
seven of the 15 currently operating smelters use roasters as
-the first pyrometallurgical operation. Roasting reduces, to
a controlled degree, the content of sulfur, as well as other
impurities contained in the feed. Two different types of
roasters are used at these seven domestic facilities; four
smelters employ multiple-hearth roasters, while the more
modern fluid-bed roaster is used by the other three plants.
A larger number of multiple-hearth roasters must be used to
produce an equal tonnage of calcine (roasted concentrate)
produced from a fluid-bed roaster.
The copper calcine is then subjected to the smelting step in
either a reverberatory furnace (reverb) or an electric
furnace. Conventionally, the calcine is charged to the
reverb along with copper-bearing scrap, cement copper (i.e.,
a beneficiation product cf low-grade copper ores), recycled
converter slag, and flue dusts collected by particulate
removal equipment. Fluxing materials, such as limestone,
are also added to enable the formation of the smelting waste
material, slag. A small portion of the total copper will
also be present in the slag. The main objective of
treatment in a reverb is to collect virtually all of the
copper in a molten copper-iron-sulfide material called
matte, suitable for subsequent treatment in converters.
Heat is supplied to the charge by the burning of powdered
coal, oil, or gas (electrical energy in the case of the
electric furnace).
The molten matte and slag flow to the discharge end of the
furnace and are tapped off into ladles. The slag is
discarded to waste and the matte, while still liquid, is
charged into the converters.
Typical compositions (in percent) of matte and slag are
shewn in the following tabulation:
Matte
Copper 45.0 43.4 31.6 27.2 0.6 0.43 0.4 0.34
iron 23.0 22.7 35.0 40.7 42.5 34.5 35.0 40.7
Sulfur 24.0 25.0 25.0 24.0
Si02 —- — — — 34.5 39.2 37.0 37.6
CaO — — — — 5.8 6.8 5.0 3.5
A1203 -- — — — 6.3 4.8 7.2 9.6
27
-------
Of the seven domestic smelters which practice the roasting*
smelting-ccnverting scheme, six use reverbs, while an
electric furnace is used by only one smelter.
The matte produced in the reverberatory furnace is then
charged to a converter where it is converted to a relatively
impure form of copper called blister copper by an oxidation
process involving the blowing of thin streams of air through
the molten material. The operation is done in two stages.
In the first, the iron sulfide component of the matte is
oxidized to sulfur dioxide and iron oxide, leaving nearly
all of the copper as molten copper sulfide or "white metal".
The iron oxide formed during converting reacts with silica,
added as a flux to the converting operation, to form a
molten iron silicate slag. The reaction occurring in the
first stage of converting is approximately:
2CuFeS2 + HO2 + 2SiO2 3SO2 + 2FeSiO3 + Cu2S.
Matte Added Silica Sulfur Iron silicate Cuprous
as air added dioxide slag removed sulfide
for and returned (white
fluxing to smelting metal)
step
When this reaction is completed, the slag is removed from
the converter. Because converter slag normally contains
significant concentrations of copper, it is recirculated to
the smelting step. After removal of the converter slag, the
blowing with air is continued until virtually all of the
remaining sulfur is oxidized and removed as sulfur dioxide,
in accordance with the overall reaction:
Cu2S -f O2 2 Cu + SO2.
The converted copper is still relatively impure, containing
varying arrounts of heavy metals, arsenic, and sulfur. It
also contains virtually all of the precious metals
originally present in the concentrates.
Normally, the blister copper will be transferred, while
still molten, to a refining furnace. Some, however, may be
cast into pigs prior to subsequent refining. When cast, it
exhibits a typically rough upper surface upon solidification
caused by the expulsion of gases (mainly air and sulfur
dioxide). This rough surface accounts for the name
"blister" copper.
Converting is done in large, horizontal cylindrical furnaces
up to 9 meters (30 feet) in length and about 4 meters (12
28
-------
feet) in diameter, with a centrally located aperture for
charging, unloading, and the exiting of gases. They are
also fitted with numerous tuyeres along their length through
which the air, necessary for converting, is blown. During
the converting operation, the converter is run in an upright
position with the aperture directly beneath a hood, through
which the converting gases are exhausted. The furnace
mounted on trunnions, is tilted or tipped for charging,
discharging, and inspection.
As shown by Figure 3, all seven smelters employ the
conventional converter as the converting-step equipment.
Typical analyses of blister copper produced by converting
are shown in Table 5.
Smelting and Converting. The remaining eight domestic
smelters practice the pyrometallurgical sequence of smelting
and converting. The charge, as fed -to the reverberatory
furnace (or in one case, an electric furnace), must have
relatively uniform consistency of concentrate constituents
in order to obviate the usage of a roaster. All eight
smelters employ reverbs; one uses an electric furnace in a
new smelter configuration {discussed later in greater
depth), operating in parallel to its older conventional
operation. This same smelter uses syphon converters as its
"new smelter" converting equipment; whereas, the remaining
seven operations, as well as this one smelter•s "old
parallel" operation, employ conventional converters. The
one important difference between these two converters is
that suction is continuously drawn through a port in the
side of the syphon converter, allowing essentially no escape
of fugitive sulfur oxide emissions during converter roll-
out. One of the eight smelters uses a bank of multiple
hearth roasters for concentrate drying purposes only.
The process of smelting and converting for this scheme is
essentially the same as that described for the
roasting-smelting-converting processing scheme, with the end
product again being blister copper.
Fire-Refining, and Anode Copper Casting. Fire-refining is a
pyrometallurgical operation, wherein blister copper is
further refined as either fire-refined copper or anode
copper, which is used in subsequent electrolytic refining.
Fire-refined copper, as a final product, constitutes only a
relatively minor percentage of the total production of
refined copper. Most primary copper is further purified by
electrolytic refining.
29
-------
TABLE 5. TYPICAL ANALYSES OF BLISTER COPPER
OJ
o
SAMPLE
Cu
PERCENT
TROY OZ./TON
As
Sb
Pb
N1
Zn
Fe
Au
AS.
1 98.4 0.02 0.178 0.001 0.005 0.003 0.13 0.20 0.295 111.9
2 98.8 0.10 0.04 0.15 0.05 0.12 0.25 0.17 0.31 30.25
3 99.5 0.035 0.015 0.001 0.04 0.002 0.03 0.06 0.02 2.50
-------
Anode furnace refining is used -to produce electrodes for
subsequent electrolytic refining. The purpose of anode
furnace refining is to purify and degas the blister copper
so that the anodes produced will be physically and
chemically acceptable for electrolysis. The refining
removes the large amounts of cuprous oxide and other
impurities, which, if allowed to reirain in the anodes, would
segregate and weaken their structure and result in rough
surfaces. Weak, ncnhomogeneous anodes with nonflat surfaces
complicate the electrolytic operation, and the presence of
cuprous oxide results in an unwanted increase in copper
content of the electrolyte.
Anode furnace refining is done in two kinds of furnaces:
(1) In reverberatory furnaces somewhat similar
to, but considerably smaller than, the
reverberatory furnaces used in matte
smelting. Such furnaces are used for
refining solidified blister copper that
has been previously cast into pigs and
high-grade scrap.
(2) In cylindrical furnaces similar to, but
smaller than, the previously described
converters. These furnaces can be
tilted on trunnions in somewhat the
same fashion as converters and are
designed to accept molten charges of
blister copper directly from converters.
Refining furnaces are fueled by coal,
natural gas, or oil.
The operation is carried out by introducing air beneath the
molten metal surface to oxidize part of the copper to
cuprous oxide. The cuprous oxide, soluble in molten copper,
reacts with sulfur, zinc, tin, or iron present in the copper
to form sulfur dioxide and tretal oxides. Sulfur dioxide
passes off as a gas, and the oxides of iron, zinc, and tin,
with added silica, form a slag that can be removed by
skimming. Other impurities such as lead, arsenic, and
antimony are only partially removed by this method. Other
metals that may be present in the copper, such as gold,
silver, and nickel, and part of the metalloids selenium and
tellurium, are only partially oxidized and remain with the
copper.
After oxidation and slag removal are accomplished, the
copper contains considerable oxygen as cuprous oxide, which
must be removed before casting. Deoxidation is done
traditionally by the addition of coke and by "poling".
31
-------
Poling amounts to inserting large poles of green hardwood
beneath the surface of the copper and allowing them to
decompose into reducing gases. These gases reduce the
cuprous oxide to copper metal. An alternative for reducing
cuprous oxide is to pass reformed natural gas through the
bath of molten copper.
After reduction, if electrolytic refining is to follow, the
refined copper is cast into anodes. If fire-refined copper
is the desired end product, casting into various "refinery"
shapes, such as wirebar, billets, cakes, and ingots, is
performed.
Fire-refined copper must conform to a fairly stringent
purity. Dependent on their subsequent use, the wirebar,
cakes, and billets, to meet specifications, must contain a
minimum of 99.5 to 99.85 percent copper. Any silver present
may be counted as copper. Metal and metalloid impurities,
such as arsenic, nickel, bismuth, lead, etc. , are also
rigidly limited.
Anodes, which represent the major tonnage of smelter
production, are cast into rectangular shapes of various
sizes and weights, depending on specific refinery practice.
A typical anode will be about 0.9 to 1 meter (36 to 39
inches) wide, 0.9 to 1 meter (35 to 39 inches) long, about 3
to U centimeters (1.25 to 1.5 inches) thick, weigh from
about 340 to 360 kilograms (750 to 800 pounds) , and contain
about 99.5 percent of copper.
Electrolytic Refining. There are 11 known primary
electrolytic copper refinery operations in the United
States. These are portrayed in Figure 4 and tabulated in
Table 6. Table 6 also contains data on age, products
produced, and processes employed by these eleven
electrolytic refineries. In this process, copper is
separated from impurities by electrolytic dissolution at the
anode and deposition as the pure metal, at the cathode. The
electrolyte is a solution of copper sulfate and sulfuric
acid. Although there is no net reaction, a transfer of
copper occurs according to the following electrode
reactions:
Anode: Cu ---- ^ Cu** + 2e
Cathode: Cu*+ + 2e — >Cu
The purpose of electrolytic refining is to produce a very
high purity copper, and, at the same time, to recover the
valuable metal and metalloid impurities that are present in
32
-------
At I
Co
Co
/ EAST NORTH CENTRAL
EA'ST SOUTH _/-—,,.«, Art AUTI
CENTRAL ^SOUTH ATLANTI
Electrolytic refinery
Fire refinery
Figure 4. Location of copper refineries in the United States.
-------
TABLE 6. CHARACTERISTICS OF PRIMARY COPPER
ELECTROLYTIC REFINERIES
U)
COMPANY/
LOCATION
ASARCO/
Baltimore, Md.
ASARCO/
Perth Amboy, N.J.
Anaconda/
Perth Amboy, N.J.
AGE
1850
1899
1899
PRODUCTS
Sleet. Ref. Cu:
144,OOOT/yr.op.
(318,OOOT/yrcap.)
Gold, Silver, Se,
Te, NiS04.
Sleet. Ref. Cu:
160,OOOT/yr,
Sold, Silver, Al.
Elect. Ref Cu:
113,OOOT/yr,
Sold, Silver, Te,
Se, Pt, Pd.
OTHER
ASSOCIATED
FACILITIES
None
None
None
PROCESS DESCRIPTION
AND
AIR POLLUTION
CONTROL
No fit?e - refining.
Electrolytic refining
with slimes recovery.
Wet and dry a. p. cont.
Melting, refining, and
casting of copper and
copper base alloys,
aluminum and precious
metals.
No a, p. cont.
Scrap and blister copper
melted down in reverb
and cast into anodes,
which are sent to electrol.
refinery. Dore Furnace
used in precious metal
separation.
No a. p. cont. required.
I
-------
TABLE 6. (Continued)
COMPANY/
LOCATION
Anaconda/
Great Falls, Mt.
Kennecott/
Baltimore, Md.
Phelps - Dodge/
El Paso, Texas
Phelps - Dodge/
Mespeth, N.Y.
AGE
1895
1959
1930
1888
PRODUCTS
Elect. Ref. Cu:
175,OOOT/yr,
CuS04 .
Elect. Ref. Cu:
178,OOOT/yr.
Slimes (shipped
elsewhere) ,
Black acid,
NiS04
Elect. Ref. Cu:
417,OOOT/yr,
Gold, Silver,
CuS04
Elect. Ref. Cu:
125,OOOT/yr,
CuS04
OTHER
ASSOCIATED
FACILITIES
None
None
None
None
PROCESS DESCRIPTION
AND
AIR POLLUTION
CONTROL
Anode scrap and scrap copper
remelted into ancrfes .
Anodes electrolytically
refined.
A. P. Cont. - Unknown
No fire - refining.
Electrolytic refining,
no slimes recovery.
Both dry and wet a. p. cont.
Anodes and blister copper
(Some cast into anodes)
elect, refined with slimes
recovery.
A. P. control - unknown
Incidental fire - refining.
Anodes and #1 scrap wire
. elect, refined. Slimes to
another plant .
Dry a. P. cont.
U)
-------
TABLE 6. (Continued)
COMPANY/
LOCATION
ASARCO/
Tacoma, Wash.
Inspiration/
Miami, Arizona
Kennecott/
Garfield, Utah
Magma/
San Mannel, Arizona
AGE
1890
1911
1900
1955
PRODUCTS
Elect. Ref. Cu:
120,000 T/yr,
Gold, Silver,
NiS04
Elect. Ref. Cu:
75,OOOT/yr,
Gold, Silver, Se.
Elect. Ref. Cu:
260,OOOT/yr,
Gold, Silver, Se.
Elect. Ref. Cu:
57,OOOT/yr, op.
(200,OOOT/yr cap)
Gold, Silver (hot
in slimes) .
OTHER
ASSOCIATED
FACILITIES
Custom ASARCO
!acoma Copper
Smelter
integrated
Inspiration
Copper Smelter
Miami, Arizona
integrated
Cennecott
Garfield Copper
Smelter
integrated
Kagna Copper
Smelter, San
flanuel, Arizona
PROCESS DESCRIPTION
AND
AIR POLLUTION
CONTROL
Anode Casting, elect.
refining, wirebar casting.
Both wet and dry a. p. cont.
Elect, ref. of copper.
A. P. cont. - unknown
Elect. Ref. of Smelter
anodes. Slimes recovery.
Both wet and dry a. p. cont.
Anodes electrolytically
refined. Cast into wire rod.
Slimes recovery unknown
A. P. cont. - unknown.
CO
en
-------
-the fire-refined, or more properly, anode furnace-refined
copper. The impurities in the anode copper either dissolve
in the electrolyte or fall to the bottom of the cells as a
slime.
A simplified flow diagram of a typical electrolytic refinery
from Lanier (9) is shown in Figure 5.
Typical analyses of anodes, electrolyte, refined copper and
slime, as described by Lanier (9), are presented in Table 7.
Some of the copper that goes into solution is not
transferred to the cathode. The major impurity in the anode
is copper oxide, Cu2O, amounting to a few tenths of a
percent. This reacts with the sulfuric acid, resulting in
precipitation of one-half of the copper and dissolution of
-the other half:
Cu2C * H2SO4 >CuSO4 + Cu + H2O.
The precipitated copper falls into the slime, where it is
later recovered. The half of the copper which goes into
solution causes a gradual buildup cf copper concentration in
the electrolyte. This is removed by the special "liberator"
cells described later.
Electrolytic refining is carried out in the following
manner. The electrolytic tanks are rectangular vessels
about 3 to 5 meters (10 to 15 feet) long, about 1 meter (3
to 3-1/2 feet) wide, and about 1 to 1.25 meters (3-1/2 to 4
feet) deep. They are usually constructed of concrete, lined
with lead or antimonial lead.
There may be from 1,000 to 2,000 cells in a typical
refinery. Each tank is fitted with heavy copper bars on the
top for supporting the anodes (and cathodes) and through
which the electric current flows. The anodes, cast with
lugs or hooks, are hung on these bars at regulated spaces of
about 9 to 11 centimeters (3.5 to 4.5 in.) apart. The
cathodes are thin sheets of electrolytically refined copper
2.5 to 5 centimeters (1 to 2 in.) longer and wider than the
anodes, but only about 0*06 centimeter (0.025 inch) thick
and weighing approximately 3.5 to 4.5 kilograms (8 to 10
pounds). These cathodes, called "starter sheets", are made
in a separate section of the refinery. The starter sheets
are fitted with loops cf copper at their tops, through which
copper bars are inserted. The copper tars serve the same
function as the lugs on the cathode. When loaded, the
electrolytic tank will contain from 30 to 40 cathodes and
anodes, depending on the length of the cell and the spacing.
37
-------
Blister
copper
Electrolytic
cells
Slirne
Steam to recovery
Heated electrolyte
Heat
Exchanger
Condensate
Liberator
cells
Copper flow
Copper
Product
Decopperized
electrolyte
Figure 5. Generalized flow diagram of electrolytic copper refinery
-------
TABLE 7. GENERAL RANGE-ANALYSIS OF ANODE, ELECTROLYTE,
REFINED COPPER, AND ANODE SLIMED)
Constituent
Sulfuric acid
Copper
Oxygen
S ulfur
Arsenic
Antimony
Bismuth
Lead
Nickel
Selenium
Tellurium
Gold
Silver
Anode, Electrolyte,
% g/1
99.0-99
0. 1-0.
0. 003-0.
0.003
0. 001
0.001
0. 01
0. 01
0. 01
-o.
-0.
-o.
-o.
-o.
-o.
170-230
.6 45-50
3
01
2 0.5-12
1 0.2-0.7
01 0.1-0.5
2
2 2.0-20.0
06
0.001-0. 02
3.4-102.6(b)
0. 1-3. 0(c)
68-3Q8Q(b)
2-9o(c)
Refined Copper,
99
0. 03
0.001
0.0001
0. 0002
0.00001
0.0002
0. 0001
0. 0003
0.0001
0.068
0.002
1.71
0. 05
Raw Slime,
(Dry Basis)
.95
-0.05
-0. 002
-0.
-0.
-o.
-o.
-0.
-0.
-0.
-o.
-o.
-17
-o.
001
001
0002
0010
002
001
0009
342 (b)
oifc)
.Kb)
0
0
2
0
1
20-40
2-6
.5-4.
.5-5.
.0-15
. 1-2.
.0-20
0
0
m
0
m
0
0
0. 5-8. 0
0. 17-1.03
50-300(c)
3.4-27.4
1000-8000(c)
(a) Extremes omitted.
(b) g/kkg.
(c) Troy oz (31.103 g) per short ton.
39
-------
These anodes and cathodes are almost entirely immersed in
the electrolyte, a dilute solution of sulfuric acid and
copper sulfate. Typical electrolytes contain about 40 g/1
of copper and up to about 200 g/1 of free sulfuric acid.
When loaded, the cell is returned to operation in the
refining circuit. The entire refining circuit may consist
of a thousand or more of such tanks, arranged in optimum
configurations for the circulation of the electrolyte from
tank to tank, the electrical current flow, and the
systematic operation of the refinery.
When electricity is flowing, the current first traverses the
anodes, where copper and impurities such as nickel, arsenic,
and iron are electrolytically oxidized and put into
solution. Gold, silver, seleniuir, and tellurium do not.
oxidize and go into solution as finely divided solids called
slimes, which settle to the bottom of the tank.
The current then traverses the electrolyte to the cathode,
where reduction and deposition of the copper takes place.
This is a highly selective operation; wherein, soluble
impurities such as nickel, arsenic, bismuth, and antimony
are not deposited with the copper (so long as they are kept
below certain concentrations in solution). Operating
conditions and schedules for preventing or minimizing the
effect of such interferences have been thoroughly developed.
As the copper is deposited, the current traverses the
cathode, enters a so-called support bar, which is connected
to the next tank in line and becomes the anode bar for that
tank. Here, the same process is repeated and rerepeated
through the entire circuit. After operation for about 2
weeks, by which time the cathode of pure copper has grown to
a weight of about 40 percent of the original anode, the
cathodes are removed and washed, and new starting sheets are
inserted on each side of the anodes. The electrolysis is
resumed for another period of about 2 weeks to produce a
second cathode of approximately the same weight. The anode,
now 80 to 90 percent consumed, is removed from the tank,
washed, and sent back to the anode refining section of the
plant, where it is remelted and recast into a full-sized
anode. Complete, or nearly complete, dissolution of anodes
in the electrolytic process is impractical, and would lead
to mechanical failures of the metal, with attendant short
circuiting.
Periodically, the slimes which have accumulated in the
tanks, and which contain precious metals and other values,
are removed and sent to refining operations for the recovery
of these values.
40
-------
Electrolyte Purification. As noted above, the electrolyte
builds up concentrations of soluble impurities (e.g.,
nickel, arsenic, antimony, and bismuth), and the copper
content rises above the optimum level, owing to the
dissolution of cuprous oxide. Control of the copper
concentration and of the concentration of these impurities
to tolerable limits is achieved by either continuously or
intermittently withdrawing a portion of the electrolyte from
the circuit and replacing it with fresh solution.
Various methods are employed for the recovery of copper and
other values in this withdrawn or bleed-off solution. In
the most widely practiced method, the copper in the bleed-
off solution is electrolytically stripped by passing the
solution through liberator cells, similar to the refining
cells, but employing insoluble (e.g., iron or lead) anodes
in place cf copper anodes- In this operation, where there
is no copper anode to supply the ccpper continuously to the
solution, the effect of the electrolysis is to drive the
copper out of solution as copper metal onto a cathode.
Frequently, two stages of liberator cells are used, with the
electrolyte flowing by gravity through the cascade. The
copper content of the discharge from the first stage may be
8 to 20 g/1; in some plants the bulk of this partially
stripped electrolyte will be returned to the tank house,
with a smaller bleed continuing on to second-stage
stripping, where the electrolyte will be nearly completely
decopperized to 0.1 to 0.2 g/1. The quality of the copper
deposited deteriorates as the copper concentration is
depleted, ultimately forming a loosely adherent sludge.
Copper from the first stage may be acceptable for the
refined copper furnaces; lower quality cathodes will be
returned to the anode casting furnace, or the high-impurity
cathodes may be returned to the smelter.
As noted by Lanier (9), the voltage increases through the
circuit, and the current efficiency drops to 25 to 40
percent. The final stage of liberator cells must be hooded
or placed out of doors, because, as the copper content drops
below about 3 g/1, arsenic reacts at the cathode and a
portion of it forms arsine, AsH3, which is volatile and
poisonous.
The decopperized solution is sometimes transferred to an
open evaporator or vacuum evaporator for further
concentration and recovery of nickel sulfate. The residual
"black acid" . liquid remaining after crystallization of the
nickel sulfate may be returned to the refining circuit, used
41
-------
for leaching operations, or disposed of elsewhere for such
uses as fertilizer manufacture.
Slimes Treatment.. The insoluble metals and compounds that
settle to the bottom of the electrolytic cells, known as
anode muds or slimes, are complex mixtures of base metals,
precious metals, and selenium and tellurium. These slimes
are withdrawn from the cells at intervals and pumped to a
treatment plant. The first treatment step may be passage
across a trommel screen to remove par-ticulate copper,
followed by a sulfuric acid leach to more completely
decopperize the slimes. After filtering and washing, the
cake is sent to a small reverberatory furnace, called a Dore
furnace, and fused. The-first slag formed ("sharp slag",
so-called because of its fracture characteristics) contains
lead and is removed and sent to a lead smelter for recovery
of the lead. Soda ash and sodium nitrate are then added to
flux the selenium and tellurium into a "soda" slag. During
smelting, some selenium and tellurium are lost by
volatilization; these fumes may be recovered by passing the
flue gases through a scrubber or an electrostatic
precipitator.
Owing to the differences in slimes composition, there are
considerable differences in slime treatment flowsheets. The
selenium-tellurium recovery process, described by Lansche
(10) and illustrated in Figure 6, has been selected as
typical.
The soda slag, containing the selenium and tellurium, is
dissolved in hot water and filtered; the residue is returned
to the Dore furnace. The filtrate is acidified to a pH of
about 5.5, precipitating TeO2, which is filtered off for
additional refining steps. The filtrate, containing the
selenium, is acidified with H2SO^, and treated with sulfur
dioxide gas to reduce the selenium to metal. The
precipitated selenium is filtered, dried, and packaged for
shipment. The finished product has a minimum selenium
content of 99.5 percent.
The crude TeO2 filter cake is treated with a sodium
hydroxide-sodium sulfide solution to redissolve the
tellurium. Precious metals, which may be present at this
stage, remain in the insoluble residue, which is filtered
off and returned to the Dore furnace. The filtrate is
reacidified to a pH of 5.5, reprecipitating tellurium
dioxide. This may be dried, ground, and sold as such, or it
may te reduced to metallic tellurium by a pyrometallurgical
treatment. Alternatively, tellurium may be reduced to the
metal in an HCl solution by reduction with gaseous sulfur
42
-------
Hot water
Residue
Dore
furnace
Smelting
slag
t
Soda slag
I
Rod mill
Leach tank
Solution
Dore'
furnace
t
Flue gas
Scrubber solution
, vapo rato r
Storage tank
Neutralizing tank
Se-Te separation
Stack
(Te)
(Se)
Filter cake
Se bearing solution
NaOH
Na2S
Agitator
Filter
Dore turnace
Te bearing
solution
>
•- Agitator
Filter
Purified
Reduced
and cast
Purified tellurium:
Grind,
sc reen,
pack, and
ship
Se precipitation
tank
Filter box
Selenium:
Dry,
grind,
sc reen,
pack, and
ship
SO2
Solutic n
Neutralise
Sewe r
(or treat I
Figure 6. Flowsheet of selenium-tellurium recovery process,
43
-------
dioxide, or it may be dissolved in caustic and electrolyzed
to produce commercial-grade tellurium.
After the removal of the soda slag containing the selenium
and tellurium from the slimes smelting furnace, air is
bubbled through the pool of metal to oxidize any copper
present, and the copper oxide is skimmed off. The remainder
(Dore metal), containing the precious metals, is cast into
anodes and sent to the silver refinery. Here, in a nitrate
solution, the silver is electrolytically refined. The gold
and any platinum metals present do not dissolve, but collect
as slimes. These are melted and cast into anodes for
electrolytic refining. These precious metal operations are,
of course, on a sirall scale (kilograms per day rather than
tons) and are more a laboratory than an industrial process.
As discussed later, slimes treatment is practiced to various
degrees at only a few refineries. Most primary electrolytic
refineries collect the slimes and ship them to another
facility for treatment.
Primary Copper Smelting and Refinin
-------
converters. No discharges of process waste water pollutants
are anticipated from the facility. Both process waste water
and sewage will be collected in an impoundment area and
disposed of through solar evaporation. The offgases from
the flash furnace and converters will be high in sulfur
oxide content and will be used for the manufacture of both
metallurgical sulfuric acid and elemental sulfur.
Another new replacement smelter currently in start-up
contains an electric furnace and syphon converters for the
production of copper. Offgases from the devices will be
controlled by a new double contact metallurgical sulfuric
acid plant. Existing contact cooling and electrolytic
refining equipment will be retained. The modified smelter,
as well as its predecessor, operate at no discharge of
process waste water pollutants.
The fourth new smelter will be a partial smelter
replacement, and is anticipated to become operational by
late 1975. A fluid-bed roaster and an electric furnace will
replace the currently operating multiple-hearth roasters
(for drying only) and reverberatory furnaces. Slag
granulation, as currently practiced, will be stopped with
the start-up of the modified facility.
A new primary copper electrolytic refinery is currently
under construction in the Southwest. Its capacity will
replace that cf an older primary refinery due to cease
operation in 1975. There will be no anticipated discharges
of process waste water pollutants tc navigable waters from
this new facility.
Lastly, one producer of primary copper is currently
constructing a hydrometallurgical facility. Start-up is
planned for September 1974, and anticipated production of
"cathode quality" copper is 90 kkg(100 ton)/day. Pilot
studies have indicated that two process waste effluents will
result from the ammonia-oxygen leaching operation. The
first will result from the sulfate residue after leaching.
The proposed treatment practice for the effluent will be
liming with high temperature. The resulting gypsum and
reaction water will be impounded in a lined pond. The
second process waste water will principally contain
unreacted pyrite produced by a short leaching operation. In
order to retain the high silver minerals, such as argentite
and lornite for further processing, these minerals are
floated and unreacted pyrites are the waste material. The
pyrite waste will be limed in a separate lined pond. The
overflow from both gypsum ponds will be pumped to two
existing ponds, and a one to two year retention time is
45
-------
anticipated for these two effluents prior to final discharge
to navigable waters. The exact characteristics and flow
volumes of these two effluents are nor as yet known.
Manuf acturing Process Summary. The preceding narrative
described the processes used, or anticipated for use, by the
primary copper industry. This industry is comprised of 15
currently operating primary copper smelters, 11 of which are
integrated with primary mining and/or milling operations,
and 11 electrolytic refineries, four of which are located on
the same site with a primary smelter. Seven electrolytic
refineries are operated separately from the smelting
operations. These primary copper industry characteristics
are illustrated in Figure 7. Four new pyrometallurgical
smelter and smelter modifications, as well as one new
replacement refinery and one new hydrometallurgical primary
copper operation, are currently under design, construction,
or start-up.
Based upon the above discussion, the processes used at all
15 primary smelters, including, those four with electrolytic
refineries, justify a separate subcategory for these plants.
By the same reasoning, the seven domestic primary copper
electrolytic refineries, which are cperated separately from
the primary copper smelters, are considered as a separate
subcategory. Data is currently insufficient for
categorization of the new hydrometallurgical operation.
Raw Materials
The principal raw material of the primary copper industry
is, of course, copper concentrate. There are about 160
known copper minerals, but only about a dozen of these are
commercially important; five or six account for over 90
percent of the copper concentrate produced in the United
States. The minerals of importance are listed in Table 8.
The most important type of copper ore in the United states
is mined from the so-called "porphyry" copper deposits.
These are extensive masses of rock throughout which crystals
of various copper minerals are more or less uniformly
disseminated, and which, although of low grade, may be
profitably mined on a massive nonselective scale. The
copper minerals generally associated with the porphyrys are
the various oxides, such as cuprite and malachite, which
have been converted to these oxide forms by weathering
processes, and, lower in the deposit, various sulfide
minerals such as chalcocite, covellite, and chalcopyrite.
The porphyry copper deposits account for the major portion
of copper production. The average grade of ore for all
46
-------
Integrated
Smelters Without
Electrolytic,
Refineries
(8)
Integrated
Smelters
4—With—\
tElectrolytic »
Refineries
(3)
Blister and
Fire-Refined
Copper
To Market
(Custom Smeltersj
Without Electrolytic
~~ Refineries
(3)
Custom Smelters
| With ^-|
EleQtrolytici Ref ine.ries
1
(1)
Cathode Copper
To Market
Blister and
Fire-Refined
Copper
Cathode Copper
To Market
Electrolytic
Refineries
Only
(7)
Cathode Copper
To Market
Figure 7. Primary copper industry operating characteristics,
47
-------
TABLE 8.
COPPER MINERALS IMPORTANT IN U. S. PRODUCTION
Mineral
C ompo s itio n
Copper Content of
the Mineral Form,
percent
Native copper metal
Chalcopyrite
Chalcocite
Covellite
Bornite
Enargite
Cuprite
Malachite
Azurite
Chrysocolla
Cu
Sulfide Ores
CuFeS2
Cu2S
CuS
Cu.FeS^
Cu3As5S4
Oxide Ores
CuzO
CuCO3-Cu(OH)2
ZCuCO3-Cu(OH)2
CuSiO3-2H20
100
35
80
66
63
48
89
57
55
36
Source: McMahon - "Copper, A Materials Survey"
48
-------
copper production in 1968 was 0.6 percent. The copper
content of the porphyry ores, therefore, must lie around 0.6
percent. Porphyry ores are mined ty open-pit methods.
Other major types of ore are the vein, pipe, and bedded
deposits, which generally yield higher grade ores ranging
from three to about ten percent copper, and which are
usually mined by underground methods. The copper minerals
in such deposits are sulfidic, frequently associated with
sulfides of other metals such as pyrite or pyrrhotite and
include chalcopyrite, bcrnite, chalcocite, and covellite. A
few of the deep United States copper deposits contain some
copper-arsenic minerals such as enargite or tennantite.
Native copper may occur in unirrportant quantities in
oxidized ore deposits, but in one place in the United States
(Michigan), it is a significant ore mineral associated with
covellite, a copper sulfide. Minor, though economically
important, concentrations of copper, generally as sulfide
(but occasionally as an oxidic material) , are also found
with the ores of other metals (lead, zinc, silver, iron).
Most of the copper sulfide ores mined in the United States
contain gold and silver in small, but economically
significant, concentrations. These are recoverable as such
in the conventional smelting-electrolytic refining process,
but not in most processes involving leaching or
fire-refining. The sulfide copper ores often contain
molybdenum in important amounts, which can be readily
recovered as a side-stream concentration operation.
While there are differences in composition and the mode of
occurrence between deposits, sometimes sufficient to cause
problems in achieving satisfactory recoveries in
concentrating, these do not propagate through the smelting
and refining steps, at least with respect to waste
effluents. The same pollutants will generally be found,
with differences only in concentration. The ore processed
by one producer in the Great Lakes region, which is
essentially a chalcocite or covellite ore, is notably free
of all extraneous trace metals other than silver. A
separate subcategory for this one smelter based on raw
material is not justified.
As stated in the above paragraph, problems in achieving
satisfactory recoveries during the milling practice of
various ores can be complicated by the type of ore being
processed. Many of these problems have been solved through
years of investigative study and practical application. Any
copper recovery problems associated with the usage of
49
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"recycle or reuse" process waste water from smelters and
refineries has not, as yet, been clearly definitized. Until
substantiating data become available to clearly indicate a
loss in floatation recovery value, a sutcategorization based
upon differences in raw materials is not warranted.
Products Produced
The products of the primary copper industry are listed by
primary ccpper operation in Tables 4 and 6. For the 15
currently operating domestic smelters, the most significant
product is refined (both anode and cathode) copper.
Additional products and byproducts include sulfuric acid,
liquid SO2., As£O3, and electrolytic refinery byproducts (for
those four primary smelters which have on-site electrolytic
refineries) such as gold, silver, selenium, tellurium,
NiSO*t, and CuSOiJ. Only one primary smelter recovers As2O^.
This one smelter processes concentrates of higher than
average arsenic content. One other domestic copper smelter
has an associated iron pelletizing and chemicals operation
on-site, but the copper smelter is a distinct operation.
Some of the seven primary copper electrolytic refineries,
which operate separately from the smelters, produce cathode
copper cast into various forms and shapes, gold, silver,
selenium, tellurium, and some alloys of copper. The
remaining refineries ship their slimes to other plants for
byproduct recovery. Tonnages of all of the preceding
products except cathode copper are insignificant relative to
the tonnage of product cathode copper. This same tonnage
comparison between blister and refined copper and associated
smelter byproducts also exists for the 15 primary copper
smelters.
As discussed in the next section of this document, the same
pollutants will be found in waste water effluents whether or
not these byproducts are recovered. Sufficient differences
in pollutants and treatment problems caused by a difference
in products or byproducts does not warrant a
subcategorization of the industry.
Wastes Generated
The largest solid waste produced at the primary copper
smelter is smelting furnace (reverberatory or electric)
slag. Most smelters dump this waste and allow it to be
cooled by air. Several smelters granulate this slag with
water.
50
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The most significant waste generated by this industry is
sulfur oxide. The evolution of this gas is specific to the
primary smelters and not to the primary refining operations.
Since, as discussed later, air pollution control specific to
the reduction of sulfur oxide emissions to the atmosphere is
prevalent at most primary smelters and since this control
produces an important source of process waste water not
found at the primary refineries, the primary copper industry
should be divided into two subcategories: (1) primary copper
smelters, with or without electrolytic refineries and (2)
electrolytic refineries, which are not contained on-site
with primary smelters.
Plant Size and Age
As illustrated by Tables 4 and 6, all of the primary copper
facilities, both smelters and refineries, are large tonnage
operations.
Many of these facilities initially commenced operation in
the latter part of the nineteenth century. Most plants have
periodically undergone partial, or complete, updating,
leaving the true plant age in doubt. Some of the older
plants, because their configurations have changed many times
during their existence, have very complex outfall systems.
The sources of process waste water combining to form these
outfalls are still evident, and many of these older plants
are performing modifications to segregate various waste
effluents.
The similarities between plants are greater than the
differences and the establishment of subcategories based on
either size or age does net appear justified on the basis of
the available data.
Plant Location
The physical plant locations of the existing primary copper
smelters and refineries are shown in Figure 2 and: 4,
respectively. Most of the smelters are located in the
southwestern section of the United States. The arid climate
of this area requires the impoundment of water, as needed
for the production of copper. Control practices of process
water used by many of these facilities may dictate their
productive survival. Other primary smelting operations, not
located in this arid region, are currently employing various
control practices of waste effluents in an effort to
minimize their existence. These ccntrol practices, as well
as process waste water treatment practices, are discussed in
detail in Section VII.
51
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Electrolytic refineries are most diverse in location, with
six on tidewater (one each in Washington and New York, two
in Maryland, and two in New Jersey). Five of these primary
refineries are not located on the same site with a primary
smelter. Two other refineries, one each in Montana and El
Paso, are also not physically located on-site with a primary
smelter. Four of the 11 currently operating primary copper
refineries are contained on-site with primary smelters.
Two possibilities exist for suhcategorization based upon
physical location of plants. One, which will be discussed
in depth in Section VII, is the availability of process
waste water disposal modes through reuse in integrated
mining and/or milling operations and in the hot offgases of
pyrometallurgical copper smelting operations. Primary
copper refineries, which are not located on-site with a
primary copper smelter, do not have these waste water
disposal modes available. Thus, a sutcategory for primary
copper smelters, with or without on-site primary copper
refineries, and primary copper refineries not located
on-site with primary copper smelters are two distinct
subcategories.
The other subcategorization possibility is based upon
geographical location. Smelters and refineries located in
areas of net evaporation have impoundment of process waste
waters with disposal through solar evaporation as a possible
alternative.
Air Pollution Control
If it were not controlled by air pollution abatement
equipment, the primary copper industry could emit enormous
tonnages of air pollutants to the atmosphere. Such air
pollutants include the oxides of sulfur, principally sulfur
dioxide and sulfur trioxide, and particulate matter, mostly
composed of fume sized particules of heavy metals. Through
the application of some air pollution controls, process
waste water streams may be produced.
Particulate Matter Control. The offgases from the
pyrometallurgical operations of the primary copper industry
carry varying amounts of particulate matter. The collection
of this particulate matter prior to atmospheric release is
important from both economic and environmental standpoints,
for not only is the particulate matter potentially dangerous
to public health and welfare, but its economic recycle value
is high.
52
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Generally, the hot offgases from the roasters, reverberatory
furnaces, and converters of the primary copper smelter are
first passed through a waste heat boiler, for heat recovery.
These offgases may then pass through a balloon flue, which
is a low velocity, large flue. The larger particles of
particulate will "fall out" of the gas stream in this
device, leaving the smaller fume-sized matter. The primary
particulate control device used by the existing industry is
the electrostatic precipitator (ESP), a device which first
electrically charges the particulate matter and then
collects this material at oppositely charged collector
surfaces. Multiclcnes have often been used for particulate
control and one domestic smelter is currently installing a
baghouse for priirary particulate control on a new electric
furnace.
Table 4 lists the types of particulate control devices used
by each currently operating smelter.
Particulate ccntrol at primary copper refineries is
generally limited to sirall ESP or scrubber applications on
slime recovery furnace offgases. These offgases are of a
much smaller gas volume than those found at the primary
copper smelters. Specifics on particulate control, as
practiced by the primary ccpper refineries, are shown in
Table 6.
Sulfur_. Oxide Control. Oxides of sulfur, the sulfur being
contained in the copper concentrate, are released during the
principal pyrometallurgical operations at primary copper
smelters. If roasting is practiced at the smelter,
approximately 25 percent of the sulfur contained in the feed
will be converted to its oxides, primarily sulfur dioxide;
25 percent will be oxidized during smelting in the reverb or
electric furnace; and the remaining 50 percent will evolve
from the converting operation. At "green-feed" smelters
(i.e., those which feed concentrates directly to the reverb
furnace withour prior roasting), approximately 40 percent of
the sulfur contained in the feed is oxidized during smelting
in the reverb and the remaining 60 percent is evolved during
converting.
Providing that unintentional leaks of infiltrating air into
the flues are minimized and good housekeeping and operating
practices are followed, the sulfur dioxide concentration in
roaster and converter offgases can be maintained between
four to 12 percent, by volume, offgases from reverberatory
furnaces often contain much less than four percent S0.2-
Conventional, permanent control of sulfur dioxide contained
in roaster and converter gases has been by means of the
53
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single-contact metallurgical sulfuric acid plant. As
described above, the major portion of the particulate matter
is removed by ESP's, but prior to entry into the acid plant,
the gas streams must be further "cleaned11 and conditioned.
This additional control is accomplished by passing the
effluent through either (or both) an open and packed
scrubbing towerr which uses a countercurrent dilute acid
solution as the scrubbing medium. The gas stream is then
passed through an electrostatic precipitator {called "mist
precipitator"); wherein, the remaining particulate matter,
as well as SO3, are removed. The effluent is then dried of
moisture and is subjected to conversion to sulfuric acid in
the acid plant. The final gas stream, containing
approximately 2000 part per million (ppm) of SO2 is called
the acid plant "tail gas" and is normally given a final
treatment by passage though a sulfuric acid mist eliminator
(deentr ainment) device.
Several primary copper smelters have recently started-up or
are constructing, double-contact sulfuric acid plants, which
produce a final SO2 concentration in the tail gas of less
than 650 ppm.
Another sulfur oxide control technique, which has been
employed by one primary smelter for several years and is in
start-up status at two other domestic smelters, is the
dimethylaniline (DMA) system. This system is principally
comprised of a three tray absorbing tower, wherein the SO2-
bearing offgas first makes chemical contact with a DMA
solution. Most of the SO2 chemically combines with the DMA.
The other two trays in the tower are used to chemically
remove entrained DMA, gaseous DMA, and residual SO2- The
pregnant DMA solution is then passed through a stripper,
wherein a concentrated SO2 stream is generated, and the
depleted DMA is recirculated to the first tower. The
concentrated SO2 effluent is normally compressed into liquid
S02.
Several other SO2 control techniques, which have possible
application to the weak gases from the reverberatory furnace
(weak implying an SQ2 concentration below that normally used
for conventional SO2 control) , include ammonia-based
scrubbing systems, sodium sulfite/bisulfite scrubbing
systems, and calcium-based systems. None of these systems
have, as yet, been used on a production basis at domestic
copper smelters.
Total smelter offgas SO2 control may be possible through the
application of new process technology, such as flash
furnaces and continuous smelting systems. One domestic
54
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copper smelter currently under construction in New Mexico
anticipates producing both sulfuric acid and elemental
sulfur from the offgases of a flash furnace. Copper-liquid
extraction technology may result in the non-
pyrometallurgical production of copper and a resultant
minimization of air pollution. Process waste waters are
anticipated from one such operation currently under
construction in Montana, but effluent data is thus far
insufficient for further discussion.
Air pollution regulations for existing primary copper
smelters, derived through state implementation plans (as
well as Federal regulation), generally call for a 90 percent
collection of sulfur, as sulfur dioxide, contained in the
copper concentrate feed (only a minor amount of the sulfur
is retained as a solid constituent of the reverberatory
furnace slag). Federal New Source Performance Standards,
under Section 111 of the Clean Air Act of 1970, may require
a concentration limit of 650 ppm SO2, by volume and
undiluted, from all smelter offgases. All of these
regulations, whether they are in existence or are
forthcoming, are providing the impetus to installation of
permanent SO2 controls at the primary copper smelters.
Of the 15 currently operating primary copper smelters, 12
are, or will be, operating some ccnventional form of sulfur
oxide recovery device. Narratives on specific primary
copper smelter SO2 control are contained in Table 4.
Since sulfur is not a primary constituent at primary copper
refineries, any sulfur oxide discharges are, generally,
nonexistent, and sulfur oxide control is not practiced.
Summary. On a basis of air polluticn control, from both the
standpoint of particulate matter ccntrol and sulfur oxide
control, the primary copper industry should be divided into
two sufccategories: (1) primary copper smelters, with or
without electrolytic refineries and (2) electrolytic
refineries, which are not contained on-site with primary
smelters.
The primary reasons for this subcategorization are the
differences in gas volumes produced at these two types of
facilities, as well as the presence of current or pending
sulfur oxide control at the former sites.
Overall Industry Categorization Summary
The preceecing text has given sufficient reason for dividing
the primary copper industry into two subcategories, the
55
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primary copper smelting subcategory and the primary copper
refining subcategory (for all primary refineries not located
on-site with a primary smelter). The basis for this
division is due to primary differences in the two
subcategories in respect to manufacturing process, wastes
generated, plant location (i.e., with respect to applicable
control practices for primary refineries located on-site
with primary smelters), and air pollution control. Plant
location also allows the possibility of disposal of process
waste water by impoundment and sclar evaporation at some
locations. One hydrometallurgical primary copper facility
is currently under construction. Data is currently
insufficient for possible categorization.
56
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SECTION V
WASTE CHARACTERIZATION
Introduction
The sources of waste water within the primary copper
industry are set forth in this section. The kinds and
amounts of waste water constituents are identified. The
characteristics of raw waste water are presented for
facilities for which such data were available or could be
determined. In some cases, treated streams are
characterized. Effluent stream mixing before discharge or
treatment often did not permit specified process stream
characterization.
Sources of_Waste Water
The primary copper industry generates waste water in the
following processes or operations:
Slag granulation;
Acid plant blowdown (i.e., blowdown from
pretreatment scrubbers prior to sulfuric acid
plant);
- Fire-refined copper, anode copper, shot copper, and
various forms of cathode copper casting (metal
cooling);
- Refining operations such as disposal of spent
electrolyte, electrolytic refinery washing, and
slimes recovery;
Miscellaneous operations such as DMA plant blowdown
and purge, slurry overflow from dust collection
systems and wet fluid-bed roaster charge systems,
arsenic plant washdown, as well as general plant
washdown, and byproduct scrubbing, as in rhenium
recovery from molybdenum roaster offgases;
Storm water runoff commingling with process waste
waters.
Other processes and operations, which use water, exist at
primary copper facilities* These uses evolve from either
ancillary operations such as on-site power generation,
mining, milling, additional metal recovery (secondary
aluminum recovery along with primary copper refining), and
metal fabrication, or from noncontact cooling operations
such as furnace and converter hood nonocntact cooling.
57
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These additional sources of waste water evolution are not
the subject of this document and will be (or have been)
discussed in detail in subsequent (or past) rationale.
Slag Granulation
One source of process waste water found at several primary
copper smelters is slag granulation. Slag, taken from the
electric or reverberatory furnaces, contains most of the
undesirable impurities found in the feed. This waste
material is disposed of by either of two ways, waste dumping
and granulating. With slag dumping, the molten slag is
dumped onto the ground (slag pile) and allowed to air cool.
This process is also termed "pancaking". In granulating,
the slag is taken to the slag disposal area in its molten
form and is impacted by a high velocity jet of water. The
resultant waste material is finely divided and is either
stored as waste or sold as road bedding or concrete
agglomerate. When dumped, the resultant slag is essentially
unleachable, but when granulated, there may be some
solubilization with the resultant formation of process waste
water pollutants. Table 9 contains the results of the
analyses of slag granulation water samples, obtained from
three primary copper smelters during the field investigation
portion of this study. There appear to be large differences
in the concentrations of arsenic, lead, and zinc, which may
possibly be due to either differences in copper concentrate
compositions or preceding processing steps, or both. One
exceedingly high value for iron may be anomalous.
Acid Plant Slowdown
When offgases from the roasting and converting operations
(and sometimes, the smelting furnace operation) are to be
treated, either in-part or in-whole, in a metallurgical
sulfuric acid plant or liquid SO2 plant, the gases , must be
subjected to preconditioning. This preconditioning is
conventionally in the form of a hot gas electrostatic
precipitator for course particular removal; an open
scrubbing tower and a packed scrubbing tower, with dilute
sulfuric acid as the scrubbing medium (or one scrubbing
tower with two sections, one for humidifying and the other
for scrubbing); a mist precipitator, for removal of residual
SO3^ and trace particulate matter; and a drying tower, for
minimization of effluent moisture content. The conditioned
effluent then enters the metallurgical acid plant catalyst
stages, where the SO_2 is converted to sulfuric acid. It may
also enter, as discussed later, a dimethylaniline (DMA)
plant for production of liquid SO^. Due to a buildup of
soluble salts, primarily metallic sulfates and chlorides.
58
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TABLE 9. ANALYSIS OF RAW WASTE POLLUTANT CONCENTRATIONS FROM PRIMARY COPPER SLAG GRANULATION OPERATIONS
In Concentration Units of mg/1
ui
Parameter
PH
TDS
TSS
CN-
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and grease
Plant 103
7.7
140.
6.8
62.
0.005
3.7
0.001
0.12
0.04
0.04
0,0001
0.001
0.001
0.001
0.44
Plant 110
8.1
3800.
151.
310.
0.050
0.048
0.001
0.05
0.30
0.070
0.0001
0.06
0.54
0.023
0.0
Plant 102
6.4-7.6
0.030
5.70
0.042
0.604
340.
7.4
0.0001
0.16
0.040
0.100
36.
0.02
-------
and solids, a blowdown from the scrubbers and mist
precipitators is required. Bled stream volumes have been
reported to be as low as 0.161/sec (2.5gpm) from one
currently operating primary copper smelter.
The results of the analyses of acid plant blowdown samples
taken at three smelters during this investigation are
presented in Table 10. Characteristically, the effluents
are at a low pH (<2) and have very high sulfate contents,
which is not surprising since a sulfur oxide-containing
stream is being scrubbed. The particulate left by the time
the gas stream reaches the scrubbers and mist precipitators
are disproportionally high in "fume" constituents, the
heavier coarse particles either having settled out or having
been removed by the hot gas electrostatic precipitator. The
particular composition of a given fume will be a function of
the ore being processed, and will vary from plant to plant.
As indicated by Table 10, arsenic, zincr and lead are
prominent pollutants in the scrubber effluents. Analyses
for bismuth and antimony are not available, but measureable
concentrations of these would also be expected.
Copper Casting (Metal Cooling)
The blister copper from the converter will, in most
instances, be cast, after poling, into anodes weighing 340
to 360 kg (750 to 800 Ib) for electrolytic refining. This
is generally done through an anode furnace, which accepts
charges from the converter and purifies and degases the
copper to provide the physical properties desirable for
satisfactory anodes. Anode molds, typically about 1 meter x
1 meter x 4 cm (3 feet x 3 feet x 1-1/2 inches) are usually
sprayed with a thin coating of a slurry of bone ash in water
to serve as a parting compound to provide easy removal of
the anode. The irclds are usually arranged horizontally
around the rim of a large wheel. After the copper has been
poured, it is sprayed with large quantities of water to
quench and cool it. The solidified anodes may, after
removal from the molds, be suspended in cooling tanks for
further cooling. The contact cooling water will frequently
be in a closed circuit with a cooling pond or tower in the
circuit. If the buildup of bone ash and other sludge
occurs, it is removed at infrequent intervals. Sometimes a
lower quality water is used for anode casting, where the
effects of staining or water spotting are of no concern. If
both anode castings and product castings are cooled with
water from a common pond, the quality of water will be
maintained at a high level. Analyses of field samples
acquired at two plants during the investigation are
presented in Table 11. It is apparent from these results
60
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TABLE 10. ANALYSIS OF RAW WASTE POLLUTANT CONCENTRATIONS FROM PRIMARY COPPER ACID PLANT SLOWDOWN
In Concentration Units of mg/1
Parameter
pH
TDS
TSS
CN-
As
Cd
Cu
£ Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and grease
Plant 102
2.0-2.5
100.
1,400.
0.01
19.0
0.09
0.058
0.65
2.24
0.028
0.015
0.040
0.017
0.75
0.04
Plant 103
1.8
5000.
6.5
490.
0.005
8.2
0.09
0.12
0.10
0.91
0.0001
0.001
0.001
0.001
13.7
Plant 110
2
16,000
146.6
2,500
0.095
0.150
1.080
7,350
4.36
9.77
0.009
0.121
1.047
17.046
0.0
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TABLE 11. ANALYSIS OF RAW WASTE WATER USED TO COOL CAST COPPER ANODES AND REFINERY SHAPES
In Concentration Units of mg/1
Parameter
pH
IDS
TSS
SC-4
As
Cd
Cu
Fe
Pb
Hg
Se
Te
Zn
Oil and grease
Inlet
Water
7.6
1430.
0.0
240.
<0.001
<0.001
0.30
0.02
0.007
0.00350
<0.001
—
<0.001
0.0
Plant
Anode
Bosh Tank
Overflow
7.5
3700.
43.0
270.
0.11
<0.001
3.1
0.15
0.65
0.00385
0.23
—
0.01
2.0
110
Semicontin-
Wirebar uous Cake
Cooling Casting
7-8
1250.
12.5
240.
<0.001
< 0.001
0.69
0.13
0.007
.00425
< 0.001
—
0.067
0.0
8.
1400.
0.0
270.
<0.001
< 0.001
0.18
0.04
0.003
< 0.0001
<0.001
—
< 0.001
0.0
Inlet
Water
7.1-7.6
—
—
—
=0.001
0.0008
0.021
1.2
0.078
0.00004
0.040
—
0.35
0.14
Plant 102
Anode Casting
Recycle
7.4-8.4
—
—
—
<0.001
0.0001
0.42
0.80
0.19
0.00004
0.040
—
0.21
0.02
Bleed
7.4-8.4
—
—
—
<0.001
0.0011
0.81
1.1
0.35
0.00002
0.040
—
0.19
0.02
Wirebar
Recycle
8.0-8.4
—
—
—
<0.001
0.0021
3.5
1.7
0.068
0.00004
0.040
—
0.088
0.1
Cooling
Bleed
8.0-8.4
—
—
—
< 0.001
0.0024
2.8
2.8
0.073
0.00002
0.040
—
0.14
0.1
-------
that this is a much different case than for the acid plant
scrubber water and slag granulation water of Tables 10 and
9, respectively. The only pollutants picked up by the water
are copper and iron, and to a lesser extent, lead, all at
fractions of a milligram per liter. Similar procedures are
employed in quenching and cooling finished copper products
cast in what are designated as "refinery shapes", which may
be wirebar, billets, cakes or ingots.
Refinery Operations
The impure copper anodes from the smelter are transported to
the refinery, where they are placed in large rectangular
cells for purification by electrolysis. A generalized
schematic of the waste effluent streams from electrolytic
refining and their origin is shown in Figure 8.
Thin, electrolytically formed copper "starter sheets" are
used as cathodes on which the refined copper is deposited.
These starter sheets are customarily oiled for ease of
removal of the electrolytically deposited copper. The oil,
which may be a light oil of an emulsified oil, is
subsequently washed off and enters one of the plant's
aqueous streams.
Upon completion of the electrolysis, which may take several
weeks, the entire rack of cathodes is removed from the cell
and rinsed to remove adhering sulfuric acid. Various
rinsing schemes are used, with some more water conserving
than others. In the past, even though first and second
rinses were returned to the tankhouse circuit, rinsing
tended to be nonconserving of water, and effluents were
discharged. In some cases, the final rinse, using fresh,
clean water, was discarded to the sewer. Improved water
management is now more prevalent, and discharges have de-
creased. This cathode rinse circuit is readily closed by
water conservation measures.
The scrap anodes may also be rinsed before being returned to
the anode furnace for remelting and casting into new anodes,
and the same types of waste effluents (unless recycled) will
result.
The cathodes are melted in a furnace for casting into the
desired commercial shapes (i.e., billets, wirebar, cakes,
etc.). As described above, the product is normally cooled
by direct contact cooling water. This water must be of
fairly high quality to avoid staining and water spotting of
the final product. It is generally recirculated to a
cooling pond, often with some bleed. Because of the purity
63
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Cathode
Starter Sheets
Copper
Anodes
H9O
Oil
SLimes to
Byproduct
Recovery
Electrolyte
Bleed
Decopperized Acid
'Black Acid" Recycle
Recovered
Copper
Rinse
Waber
Non-
Contact
C. W.
Alt. i
Vent | Vent
to 1 to
Copper Atmos. | Atmos.
Product
AsH
Recovered Copper
— to Anode Casting
Alternate
Use or
Disposal
Contact Scrubber
C.W. Water
Fiyure 8. Generalized schematic of waste effluents from the electrolytic refining of copper.
-------
of the copper, pickup of contaminants other than copper is
minimal (see Table 11).
Most of the existing copper refineries in the U.S. are
located on tidewater, and seawater, or brackish water, is
frequently used for noncontact cooling, especially for
furnace jackets. The seawater is often used in heat
exchangers with fresh water being the actual noncontact
cooling medium. large volumes of seawater are used on a
once-through basis; the temperature rise is relatively
modest. The fresh water is usually maintained in
closed-circuit fashion.
As noted previously, there is a gradual buiIdup cf copper in
the electrolyte resulting frcm the dissolution of copper
oxide. There is also a buildup of soluble impurities,
which, depending or the copper feed material, may include
nickel, arsenic, and traces of antimony and bismuth.
If the level of these soluble impurities is low, the control
cf copper (and arsenic) may be adequately achieved by the
use of "liberator cells". After its copper content is
reduced, the side stream of electrolyte, sent through the
"liberator cells", returns to the main circuit. However,
the concentration of nickel is not affected by this
operation, and, if nickel accumulates in the solution,
additional measures are necessary. In a typical scheme,
these measures involve reducing the copper content from its
normal 40 g/1 concentration to 15 g/1 in an electrowinning
cell, followed by evaporative concentration back to 30 g/1,
with the copper then stripped completely. The resultant
solution will be further evaporated to crystallize the
nickel sulfate. The supernatant sulfuric acid (black acid)
may be returned to the tank house, or sold for use in the
manufacture of fertilizer. The nickel sulfate may be sold
as a crude product, or may be redissolved and recrystallized
in a vacuum crystallizer to produce a refined product. If a
vacuum crystallizer is used, there will be an effluent from
the barometric condenser. In the absence of mist
eliminators, there can be entrainment of solubles to the
barometric condenser cooling water.
Evolution of arsine, AsH3, a colorless toxic gas, does not
appear to be a problem in tank houses, owing to the condi-
tions of electrolysis. Arsine evolution from liberator and
electrowinning cells increases as copper concentrations
approach zero, and electrowinning cells are frequently
hooded to irinimize the possibility of arsine concentration
buildup in the cell room. The fumes may be dissipated
65
-------
-through a stack to the atmosphere; if they are scrubbed
before release, this will add another waste effluent.
selenium and _Tellurium Recovery. Electrolysis is a
continuous operation, interrupted only to change anodes or
cathodes. The insolubles ("slimes") accumulate in the
bottom of the cells. These slimes will contain the precious
metals, which are insoluble in the sulfuric acid
electrolyte, particulate copper and copper oxide, plus
varying amounts of arsenic, selenium, tellurium, and other
trace metals intrcduced with the anode copper. The slimes
are processed in an ancillary operation to recover the
precious metals. A simplified general schematic of the
waste effluents arising from the recovery operations is
shown in Figure 9.
The slimes are first treated with sulfuric acid to dissolve
as much as possible of the metallic copper and copper oxide
particulates associated with the slimes. The
copper-containing sulfuric acid solution is normally
returned to the liberator cells cr to the tank house; at
some installations, it is passed through a cementation cell
to recover the copper and then discarded. The filtered and
washed slimes cake is then sent to a small reverberatory
furnace and melted sequentially with various fluxes. The
flue gases from the furnace may be discharged directly to
the atmosphere through a stack. In seme plants, the gases
are first passed through a scrubber, to remove the bulk of
the dust and condensables and to condition the gas, and then
through an electrostatic precipitator for final cleanup
before release. The effluent from the scrubber may be
recycled, with a blowdown to control solubles
concentrations. The blowdcwn may be combined with the rest
of the byproduct plant effluents for treatment before
discharge.
The first slag withdrawn from the reverberatory furnace
("termed sharp slag" because of its glasslike fracture)
contains the lead. This slag is customarily sent to a lead
smelter and is not further processed in a copper refinery.
Sodium carbonate and sodium nitrate are added and fused to
form water soluble compounds of selenium and tellurium.
This soda slag is drawn off and leached with water to dis-
solve the selenium and telluriuir. Procedures for the
recovery of selenium and tellurium are not identical
throughout the industry, and there are characteristically
numerous recycle streams to improve separations and enhance
recoveries. According to the generalized scheme shown in
Figure 9, tellurium dioxide is precipitated by lowering the
66
-------
Slimes
CuSO4 + H2SO4
Recycle to
Tank House
SO;
Dore Metal
(As + Au + P-J-)
Recycle mud
to Dore Furnace
H2S04
Scrubber
Water
N2S04
Mother
Liquor
Refined Se Mother
Liquor
Refined TeO2
Figure 9. Generalized schematic of waste effluents from byproduct
processing (Se + Te).
67
-------
pH to 6,0 to 6.5 with sulfuric acid. The filtrate containing
the selenium is further acidified with sulfuric acid and
reduced with SQ2, precipitating the selenium as metal. The
crude TeO2 is redissolved in caustic and reprecipitated by
reacidification. An alternative method includes solution
of the tellurium dioxide in hydrochloric acid and reduction
with SO2 to precipitate metallic tellurium. If this scheme
is used, volatilization of some of the HCl occurs and a
scrubber will be added to the train. The acid scrubber
water effluent will be combined with the other effluents
from the byproduct recovery operations for treatment.
Mother liquors result from both the selenium and tellurium
precipitations. Since both selenium and tellurium are very
minor byproducts of a copper refinery (a few hundred of
thousands of kilograms per year), the volumes of these
mother liquors are not large and are on the order of a few
thousand liters per day.
Precious Metals Recovery. After the removal of the soda
slag containing the selenium and tellurium, air is bubbled
through the pool of metal to oxidize any copper present, and
the copper oxide is skimmed off. The remainder (Dore
metal), containing the precious metals is cast into anodes
and sent to the silver refinery. Here, in a nitrate
solution, the silver is electrolytically refined. The gold
is collected as a slime, which is melted and cast into
anodes for electrolytic refining. A generalized schematic
of precious metal recovery effluents is shown in Figure 10.
All of these operations are obviously on a small scale
(i.e., production is on a scale of kilograms per day rather
than tons per day). Accordingly, many operations are on a
batch basis and quantities are small. Spent electrolyte
from the silver electrolysis cells is treated batchwise,
first with copper to cement out the silver, and then with
iron to cement out the copper. The final effluent from the
cementing operation will normally be neutralized before
discharge.
The gold is electrolytically refined on not much more than a
laboratory scale. The scale is even smaller for recovery of
the platinum metals, where the entire year's production from
a refinery may be only a few kilograms. Waste effluents
from these latter operations are an insignificant fraction
of the total wastes from a refinery and were not further
considered with respect to effluent guidelines.
68
-------
Dore Metal
Anodes
HNO-
CTi
Silver
Product
Electrolytic
Cell
Cupel Electrolytic Gold
*" Furnace * Cell Product
ohme AU pfc _ pd
(Au) Anode b *• Recovery
Copper
Cement
Silver
Spent
Electrolyte
JLJL
Silver
Cementation
Copper
Cementation
Spent
Solution
Iron
Cement
Copper
Figure 10. Generalized schematic of precious metals recovery.
-------
Miscellaneous Operations
Some operations, which produce process waste water, are
classified as miscellaneous. The primary reason for this
classification is their non-uniform frequency of occurrence
at each primary copper facility. Only one plant currently
recovers arsenic trioxide from roaster and reverberatory
offgases; only three have DMA scrubbing systems. Another
reason for this classification may be the small or extremely
intermittent usage of water from these operations, such as
the periodic cleaning of holding vessels. Such intermittent
sources, not covered specifically by these effluent
limitations, must be handled on a case-by-case basis. These
miscellaneous sources of process waste water are discussed
below:
DMA Plant Purge. If a DMA scrubbing system is used on
selected smelter offgases, a purge stream, containing mostly
dissolved solids, in the form of sulfates and sulfites of
sodium, and trace amounts of DMA, results when the DMA is
separated from the scrubber media in a regenerator. The
volume of this purge stream, as well as its sodium salt
content, are principally dependent upon DMA plant capacity,
the DMA scrubbing tower operating temperature, and the SO2_
content of the treated gas stream. Purge volumes can be
reduced by the usage of sulfurous acid, in lieu of sulfuric
acid, in the DMA scrubbing tower. One plant currently under
construction anticipates a purge volume of about 0.63 I/sec
(10 gpm) .
As discussed previously in this section, gas precleaning
prior to the DMA scurbber is required. A blowdown from the
scrubbers and mist precipitator, the necessary gas
precleaning equipment, is produced, and is essentially the
same blowdown as produced by acid plant gas precleaning
equipment.
Slurry Overflow. Flue dust collected by particluate
cleaning equipment, such as electrostatic precipitators and
multiclones, is usually wet blended prior to recycle into
the smelting operation. Also, with some fluid-bed roasters,
a wet feed is required. In either wetting operation, an
excess amount of water may result.
Arsenic Plant Washdown. One domestic, currently operating
smelter produces arsenic trioxide from high arsenic flue
dusts, collected from the smelter's roaster and
reverberatory furnace offgas particulate collection system.
In order to minimize arsenic contamination, a housekeeping
practice of nosing-down the arsenic plant is employed
daily. This intermittent process waste water source was
sampled during the field investigation segment of this
70
-------
study, and the results of the analysis of this sampling are
shown in Table 12. As would be expected, concentration
values of arsenic, copper/ cadmium, lead, and zinc are very
high.
General,Plant washdown. Most plants maintain dust
accumulations and spills to a minimum by either or both
vacuuming and washdown. As with the analysis of the arsenic
plant washdown, one would expect high concentration values
of various trace metals in any general plant washdown.
Byproduct Scrubbers. One priirary copper industry
application of a byproduct scrubber is the scrubber used by
some plants to clean offgases from byproduct molybdenum
roasters. Any purge from this scrubbing system would be
expected to contain significant metal loadings.
Rainwater Runoff Commingling with Process Waste Waters
In numerous situations, the process waste waters of the
primary copper industry are commonly commingled with other
waters and collected in retention ponds. These retention
areas are used conventionally as a treatment area prior to
discharge or to recycle, if only for suspended solids
settling and waste commingling. Storm water, which is
either collected intentionally due to its high pollutant
loading after contact with smelter or refinery surfaces or
commingles with process waste water effluents (as described
above), is considered as a source of process waste water
pollutants. Other water, such as spring water, which may
enter retention area as ground seepage is also considered as
a source of process waste water after commingling occurs.
Effluent Loadings
The various sources of process waste water, outlined in the
preceding pages, are generally combined into one or more
plant outfalls. Some primary copper facilities have filed
discharge permits with the U.S. Army Corps of Engineers
through the Refuse Act Permit Program (RAPP). The RAPP data
for the primary copper smelters have been studied in detail
and have been found to be deficient for the purposes of this
section. Either the data contained in the permit was found
to be out of date or questionable, or the process waste
waters under investigation were so diluted with other waters
that raw waste characterization became highly suspect.
Attempting to gain insight on the raw waste characteristics
of acid plant blowdown when it is commingled with 75,000 cu
m/day (20 mgd) of mine, mill, and noncontact cooling water
is impossible. Also, even with dilution of the process
71
-------
TABLE 12. EXAMPLE OF RAW WASTE EFFLUENT FROM ARSENIC PLANT WASHDOWN
Parameter
pH
TDS
TSS
S04=
CN-
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and grease
Flow,
I/day
gal/day
Production,
KKG
tons
Flow/Production,
1/KKG
(a)
Concentration
(mg/1)
3.8-4.4
340.
0.01
310.
1.05
88.4
9.4
7.7
0.0003
0.75
0.04
0.43
37.
0.04
2270 - 3400
600 - 900
33 (a)
37
Gross Loadings
(KG/KKG(a))
0.0272
0.0
0.0248
0.0
0.0070
0.0007
0.0006
0.0
0.0
0.0
0.0
0.0029
0.0
Based on As20n production.
72
-------
waste waters in question, various forms of treatment, even
if only simple settling, provide accountable complications
to using RAPP data as a guide to raw waste characterization
for the primary smelters. Due to this inadequacy, much of
the basic raw waste data has been taken from the analyses of
field samples, collected during the initial investigation
segment of this industry. Three primary copper smelters
were sampled, with most of the concentration data already
presented in the previous discussion of this section. The
analyses of these samples, revealing raw waste concentration
data for slag granulation, acid plant blowdown, various
types of product contact cooling, and arsenic plant
blowdown, combined with average volumetric flow and
production rates, yield raw waste loadings for these same
process waste waters.
Table 13 lists the calculated gross raw waste loadings for
three slag granulation operations. loadings for lead, zinc,
and arsenic were found to be high. Oil and grease was found
to be negligible. Average flow per unit of production for
slag granulation calculated out tc 50,000 1/kkg (12,000
gal/ton). pH was found to be just above the neutral point.
Table 14 lists the calculated gross raw waste loadings for
three acid plant blowdown operations. Averages for the
three operations yield a significant loading for dissolved
solids (especially sulfates) and for metals, including
arsenic, cadmium, iron, lead and zinc. Average water usage
for acid plant blowdcwn per metric ton of copper produced
was found to be equal to 14,700 liters (3,5'00 gal/ton). Oil
and grease was again found to be negligible. The low pH of
2.0 was found to be the average value for this parameter.
Table 15 depicts net raw waste loads for anode and cathode
shape casting operations. Small increases are noted for the
pollutant parameters of suspended solids, dissolved solids,
and some metals, especially copper. Volumetric flow at one
plant was based upon recycle values. Oil and grease
loadings were found to be very low.
Raw waste loads for arsenic trioxide plant washdown are
shown in Table 12. Values are on a gross basis and are
calculated based upon As2O^ production, not copper
production. The value cf arsenic, as expected, is extremely
high. Other high loading constituents include sulfates,
copper and zinc.
Raw waste data for other miscellaneous sources of process
waste water were not available for this study.
73
-------
TABLE; 13. PAW WASTE CHARACTERIZATION: SLAG GRANULATION WATER
Parameter
PH
TDS
TSS
S04=
Cn~
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and Grease
Flow, 106
Units
PH
kg/kkg
. I/day
gal/day
.kkg/day
ton/day
Flow/Prod 1/kkg
Production.
Plant 102
6.4-7.6
0.0016
0.300
0.0022
0.032
[17.87](a)
0.389
0.00001
0.0084
0.0021
0.0053
1.89
0.001
16.35
4.32
311.
343.
Plant 103
7.7
10.0
0.48
4.44
0.0004
0.265
0.0001
0.009
0.003
0.003
0.0001
0.0001
0.0001
0.0001
0.032
37.85
10.1
528.
577.
Plant 110
8.1
91.2
3,6
7.44
0.0012
0.0011
0.0000
0.0012
0.0072
0.0016
0.0000
0.0014
0.0129
0.0005
0.0
15.75
4.16
655.
722.
Average
7.6
50.
2.0
5.9
0.0010
0.187
0.0007
0.014
0.005
0.130
0.00001
0.0033
0.0050
0.0027
0.64
0.0
53,000.
72,000.
24,000.
50,000.
WBracketed values not used in averaging computation.
-------
TABLE 14. RAW WASTE CHARACTERIZATION: ACID PLANT BLOWDOWN
Parameter
PH
TDS
TSS
S04=
Cn-
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and Grease
Flow, 106...,
Units
PH
kg/kkg
S02 Captured
, I/day
gal/day
Production kkg/day
ton/day
Flow/Prod 1/kkg
Plant 102
2.0-2.5
[0.99](a)
0.0000
0.044
0.0002
0.0001
0.0014
0.0051
0.0000
0.0000
0.0001
0.0000
0.0017
0.0000
0.147
0.039
20.
311.(62)
343.
2,400.
Plant 103
1.8
78.5
0.102
7.69
0.0000
0.129
0.0014
0.0018
0.0015
0.0142
0.0000
0.0000
0.0000
0.0000
0.215
4.16
1.1
50.
528.(264)
577.
15,800.
Plant 110
2.0
410.
3.74
64.0
0.0024
0.004
0.0276
[188.2]
0.1116
0.2501
0.0002
0.0030
0.0268
0.436
0.0
10.1
2.66
60.
655.(393)
722.
25,700.
Average
2.0
244.
1.92
36.0
0.0008
0.059
0.0097
0.0010
0.0382
0.0898
0.0001
0.0010
0.0090
0.0000
0.218
0.0
14,700.
Ta)Bracketed values not used in averaging computation.
-------
TABLE 15. RAW WASTE CHARACTERIZATION: CONTACT COOLING WATER
CTl
Parameter Units
pH pH
TDS kg/kkg
TSS
S04=
Cn-
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and Grease "
Flow, 106 I/day
gal/day
Production kkg/day
ton/day
Flow/Prod 1/kkg
ANODE CASTING
Plant 102
7.4-8.4
—
—
—
0.0
0.0
0.001
0.0
0.001
0.0
0.0
0.0
0.0
0.191 (a)
0.050
311.
343.
Plant 110
7.5
17.7
0.33
0.23
0.001
0.0
0.022
0.001
0.005
0.0
0.002
0.0
0.016
5.287
1.397
674.
743.
CASTING
CATHODE-SHAPE
Plant 102
8.0-8.4
0.0
0.0
0.001
0.001
0.0
0.0
0.0'
0.0
0.0
0.191
0.050
613.
7,800.
311.
343.
613.
wBased on recycle, not bleed.
-------
Tables 16 through 29 contain RAPP data (one table for each
outfall) on refineries, both ori-site with a primary copper
smelter and not on-site. Table 30 summarizes all of the net
effluent loadings for these eight primary refineries. RAPP
data were used since the selected outfalls were comprised,
on a volumetric flow basis, of mostly process waste water of
interest to this study. Due to the inclusion of some
additional sources of water into this data, apparent water
usage per ton of product is high in some cases. None of the
eight refineries were performing any significant treatment
of process waste water effluents pricr to discharge at the
time of the discharge permit application. Values of
tellurium were only reported for those three refineries
recovering selenium and tellurium as byproduct operations.
Reasonably high values for suspended and dissolved solids,
as well as some metals, including arsenic, zinc, selenium,
iron, copper, lead, and nickel, were found. One value for
oil and grease was found to be excessively high.
77
-------
TABLE 16. WASTE EFFLUENTS FROM PLANT NO. 115
Outfall No.: 001Ca)
Contributing Operations:
Anode furnace C.W.; product casting
furnace; power plant; by-products plant;
analytical laboratory; sanitary wastes
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/ day
gal/day
Production,
metric tons /day
short tons/day
Intake,
mg/1
7.0
420
7
3210
3192
18
0.1
225
2200
0.2
<1
50
0.02
0.05
0.04
87
< 0.001
0.01
18
<0.02
765
0.01
Discharge,
mg/1
7.0
420
22
3770
3710
60
1.6
2440
2340
3.1
3.0
W
71
W
7.5
35
<2
100
<0.001
3.0
97
1.7
1059
<3
0.4
6.43
1.7
494
545
Net Change
mg/1
15
560
518
42
1.5
2215
140
2.9
<2.0
21
7.5
35
<2
13
3.0
79
1.7
294
<3
0.4
, Net Loading
kg /day
96.5
3,600
3,330
270
10
14,240
900
18.6
<13
135
48
225
<13
84
19.3
510
11
1890
19.3
2.6
kg/kkg
0.20
7.29
6.74
0.55
0.02
28.6
1.82
0.04
0.026
0.27
0.10
0.46
<0.026
0.17
0.04
1.03
0.022
3.83
0.04
0.005
lb/ton
0.40
14.6
13.5
1.10
0.04
57.2
3.7
0.08
0.05
0.54
0.20
0.92
<0.05
0.34
0.08
2.1
0.04
7.6
0.08
0.01
(a) Source: RAPP.
78
-------
TABLE 17.
WASTE EFFLUENTS FROM PLANT NO. 115
Outfall No.: 002
Contributing Operations:
Electrolytic refining of copper
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/day
gal/day
Production,
metric tons/day
short tons/day
Intake,
mg/1
8.0
0
<1
134
125
9
17.9
14
20.3
<0.01
0.02
-------
TABLE 18. WASTE EFFLUENTS FROM PLANT NO. 116
Outfall No.: 001
Contributing Operations: Furnace jacket C.W.; casting cooling C.W.;
overflow from cooling tower
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/day
gal/day
Production,
metric tons/day
short tons/day
Intake,
mg/1
7.2
45
20
137
132
5
27.6
<0-01
<0.20
<0.20
<0.50
<0.50
<0.50
<0.20
Discharge,
mg/1
7.2
420
350
862
685
177
65.9
0.28
<0.20
0.38
<0.50
<0.50
<0.50
0.40
0.503
0.133
415
457
Net Change, Net Loading
mg/1 kg/day kg/kkg Ib/ton
375 190 0.45 0.92
330 166 0.40 0.80
725 365 0.88 1.76
553 280 0.67 1.34
172 87 0.21 0.42
38.3 19.3 0.046 0.092
0.27 0.14 0.0003 0.0006
0.20 0.10 0.0002 0.0004
0.20 0.10 0-0002 0.0004
(a) Source: RAPP.
80
-------
TABLE 19. WASTE EFFLUENTS FROM PLANT NO. 116
Outfall No.: 005
-------
TABLE 20. WASTE EFFLUENTS FROM PLANT NO. 117
Outfall No.: 004
Contributing Operations: Electrolytic refinery tank house; by-products
plant; I-X regeneration; power plant
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/ day
gal /day
Production,
metric tons /day
short tons/day
Intake,
mg/1
7.5
104
280
18,310
18,280
58
3.3
1,400
10,850
0.080
1.17
0.05
0.024
0.150
0.08
0.0001
0.010
0.032
0.30
0.05
Discharge, Net Change,
mg/1 mg/1
7.0
19
110
15,525
15,480
22
3.5
2,360
10,950
0.350
11.57
0.05
0.040
25.3
0.40
0.0004
2.50
0.040
3.40
0.50
4.9
1.3
293
323
neg
neg
neg
0.2
960
0.27
10.4
0.016
25.2
0.32
0.0003
2.50
0.008
3.10
0.45
Net Loading
kg /day
1.0
4720
1.3
51
0.08
125
1.6
0.001
12.3
0.04
15.3
2,2
kg/kkg
0.003
16.1
0.004
0.174
0.0002
0.43
0.005
< 0.0001
0.042
0.0001
0.052
0.008
lb/ ton
0.006
32
0.008
0.35
0.0004
0.86
0.010
< 0.0002
0.08
0.0002
0.10
0.016
(a) Source: RAPP.
82
-------
TABLE 21. WASTE EFFLUENTS FROM PLANT NO. 118
Outfall No.;
Contributing Operations: Cooling cast copper rod and other shapes
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 105
I/ day
gal/day
Production,
metric tons /day
short tons/day
Intake,
mg/1
8.2
136
258
242
16
17
55
9.0
0.33
0.02
0.005
40
0.01
0.04
0.23
0.04
14.4
3.6
29
0.06
Discharge,
mg/1
8.7
127
8.6
378
274
30
11.4
73
9.6
0.11
0.02
0.1
40
0.01
0.60
0.36
0.04
17.7
4.2
22
2.6
24.2
6.4
454
500
Net Change,
mg/1
neg
<8.6
120
32
14
neg
18
0.6
neg
0.005
0.56
0.11
3.3
0.6
neg
2.6
Net Loading
kg /day
<210
2900
775
340
440
14.5
0.12
13.6
2.7
80
14.5
63
kg/kkg lb/ ton
0.46
6.39
1.71
0.75
0.97
0.03
0.0003
0.030
0.006
0.18
0.032
0.14
(a) Source: RAPP,
83
-------
TABLE 22. WASTE EFFLUENTS FROM PLANT NO. 118
Outfall No.: 005
-------
TABLE 23. WASTE EFFLUENTS FROM PLANT NO. 119
Outfall No.: 001^
Contributing Operations: Electrolytic copper refinery; casting and furnace
C.W.; boiler blowdown; noncontact C.W.
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/ day
gal/day
Production,
metric tons/day
short tons/day
Intake,
mg/1
7.4
44
5
(113)
112
1
6.0
18.3
19.3
20.9
< 0.005
0.19
5.1
0.03
4.5
0.10
Discharge,
mg/1
6.4
58.5
260
901
87
49.6
200
10 .
69
0.066
1.58
0.55
0.042
0.085
0.950
0.160
0.55
0.145
459
506
Net Change,
mg/1
14.5
255
789
86
43.6
180
10
48
0.061
1.39
0.55
0.04
0.085
0.92
0.06
Net Loading_
kg /day
8
140
433
47
24
99
5.5
26
0.03
0.76
0.30
0.022
0.05
0.47
0.03
kg/kkg
0.017
0.305
0.94
0.10
0.05
0.22
0.010
0.06
< 0.0001
0.002
0.0006
<0.0001
0.0001
0.001
<0.0001
Ib/ton
0.034
0.61
1.88
0.20
0.10
0.44
0.02
0.12
< 0.0002
0.004
0.001
< 0.0002
0.0002
0.002
< 0.0002
(a) Source: RAPP
85
-------
TABLE 24. WASTE EFFLUENTS FROM PLANT NO. 121
Outfall No.: 002^
Contributing Operations: Anode casting cooling
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/day
gal /day
Production,
metric tons/day
short tons/day
Intake, Discharge, Net Change, Net Loading
mg/1 mg/1 mg/1 kg/day kg/kkg Ib/ton
6.6 6.8
5.3 14.0 8.7 7.8 0.029 0.058
0 . 02 0 . 14 0 . 12 0 . 11 0 . 0004 0 . 0008
0.001 0.010 0.01 0.01 <0.0001 <0.0001
0.05 8.58 8.53 8.07 0.030 0.060
0.03 0.28 0.25 0.24 0.0009 0.002
0.95
0.25
265
293
Source: RAPP.
86
-------
TABLE 25. WASTE EFFLUENTS PROM PLANT NO. 121
Outfall No.: 005
Contributing Operations: Refined copper casting mold cooling
Intake,
Parameter mg/1
pH 6.6
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride 5 . 3
Cyanide
Aluminum 0.02
Arsenic 0.001
Cadmium
Calcium
Chromium
Copper 0.05
Iron 0.05
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc 0.03
Flow, 106
I/ day
gal/day
Production,
metric tons/day
short tons/day
Discharge, Net Change, Net Loading_
mg/1 mg/1 kg/day kg/kkg Ib/ton
6.2
63.9 58.6 18.9 0.071 0.14
0.05 0.03 0.009 <0.0001 <0.0001
0.01 0.01 0.003 <0.0001 <0.0001
5.68 5.63 1.82 0.0006 0.001
0.10 0.05 0.016 <0.0001 <0.0001
0.32
0,085
265
293
(a) Source: RAPP.
87
-------
TABLE 26. WASTE EFFLUENTS FROM PLANT NO. 121
fal
Outfall No.: 008^ '
Contributing Operations: CuSO^ plant
Parameter
pH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/ day
gal/day
Production,
metric tons /day
short tons/day
Intake, Discharge,
mg/1 mg/1
6.6 6.2
5-3 80.0
0.02 0.50
0.001 0.001
0.05 4.00
0.05 1.15
0.001
0.030 0.05
0.15
0.04
265
296
Net Change, Net Loading_
mg/1 kg/day kg/kkg lb/ton
74.7 11.2 0.043 0.086
0.48 0.072 0.0002 0.0004
4.0 6.0 0.002 0.004
0.05
0.02 0.003 <0-0001
(a) Source: RAPP,
88
-------
TABLE 27. WASTE EFFLUENTS FROM PLANT NO. 102
Outfall No.: 003^
Contributing Operations: Electrolytic refinery; electrolyte purification
and recovery of precious metals
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/ day
gal/day
Production,
metric tons/day
short tons/day
Intake,
mg/1
7.0
80
5.2
150
150
1.0
36
3.7
0.10
0.001
0.01
0.01
0.02
0.08
0.10
0.001'
0.01
0.02
0.03
Discharge,
mg/1
4.6
35.4
229
194
35
1.0
56
13
0.10
0-67
0-01
0.01
0.006
6.90
0.10
0.001
1.58
0.14
0.83
1.22
0.32
311
343
Net Change, Net Loading
mg/1
30.2
79
44
35
0
20
9.3
0
0.67
0
0
neg
6.82
0
0
1.57
0.12
0.80
kg/day kg/kkg Ib/ton
36.8 0.119 0.238
96.4 0.310 0.620
53.7 0.173 0.346
42.7 0-137 0.274
24.5 0.080 0.160
11.3 0-037 0.074
0.82 0-003 0.006
8.32 0.027 0.054
1.91 0-006 0.012
0.14 0.0004 0.0008
0.98 0.003 0.006
(a) Source: RAPP.
89
-------
TABLE 28. WASTE EFFLUENTS FROM PLANT NO. 102
Outfall No,: 004
-------
TABLE 29. WASTE EFFLUENTS FROM PLANT NO. 110
Outfall No.: 004^
Contributing Operations: Electrolytic refinery
Parameter
PH
Alkalinity
COD
Total Solids
Dissolved Solids
Suspended Solids
Oil and Grease
Sulfate (as S)
Chloride
Cyanide
Aluminum
Arsenic
Cadmium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Mercury
Molybdenum
Nickel
Potassium
Selenium
Silver
Sodium
Tellurium
Zinc
Flow, 106
I/day
gal/day
Production,
metric tons /day
short tons/day
Intake,
mg/1
7.8
220
1.5
1580
1568
9
0
230
450
<0.01
<0.05
0.008
<0.001
20
0.056
0.060
0.040
<0.001
36
<0.001
0.005
0.002
34
0.024
<0.0001
370
0.020
Discharge,
mg/1
7.6
240
217
3126
2311
464
0.01
260
970
<0.01
0.20
0.065
0.020
150
0.064
0.290
0.180
<0.001
89
<0.001
2150 (10
0.051
40
0.045
0.020
780
0.001
1.48
0.39
674
743
Net Change,
mg/1
20
215
1546
743
455
0.01
30
520
0
0.20
0.057
0.02
130
0.008
0.23
0.14
53
2150
0.049
6
0.021
0,02
410
neg
Net Loading
kg /day
30
318
2290
1100
673
0.01
44.4
770
0.30
0.08
0.03
192
0.34
0.20
78
3180
0.07
8.9
0.03
0.03
610
kg/kkg
0.044
0.472
3.40
1.63
1.00
0.066
1.14
0.0004
0.0001
<0.0001
0.28
0.0005
0.0003
0.115
4.72
0.0001
0.013
<0.0001
<0.0001
0.91
Ib/ton
0-088
0.94
6.80
3.26
2.00
0.132
2.28
0-0008
0.0002
0.0001
0.56
0.001
0.0006
0.23
9.44
0.0002
0-026
0-0001
0.0001
1.82
(a) Source: RAPP.
(b) From associated molybdenite recovery operations.
91
-------
concentrated by marine organisms, particularly molluscs,
which accumulate cadmium in calcareous tissues and in the
viscera. A concentration factor of 1000 for cadmium in fish
muscle has been reported, as have concentration factors of
3000 in marine plants, and up to 29,600 in certain marine
animals. The eggs and larvae of fish are apparently more
sensitive than adult fish to poisoning by cadmium, and
crustaceans appear to be more sensitive than fish eggs and
larvae.
Copper
Copper salts occur in natural surface waters only in trace
amounts, up to about 0.05 mg/1, so that their presence
generally is the result of pollution. This is attributable
to the corrosive action of the water on copper and brass
tubing, to industrial effluents, and frequently to the use
of copper compounds for the control of undesirable plankton
organisms.
Copper is not considered to be a cumulative systemic poison
for humans, but it can cause symptoms of gastroenteritis,
with nausea and intestinal irritations, at relatively low
dosages. The limiting factor in domestic water supplies is
taste. Threshold concentrations for taste have been
generally reported in the range of 1.0-2.0 mg/1 of copper,
while as much as 5-7.5 mg/1 makes the water completely
unpalatable.
The toxicity of copper to aquatic organisms varies
significantly, not only with the species, but also with the
physical and chemical characteristics of the water,
including temperature, hardness, turbidity, and carbon
dioxide content. In hard water, the toxicity of copper
salts is reduced by the precipitation of copper carbonate or
other insoluble compounds. The sulfates of copper and zinc,
and of copper and cadmium are synergistic in their toxic
effect on fish.
Copper concentrations less than 1 mg/1 have been reported to
be toxic, particularly in soft water, to many kinds of fish,
crustaceans, mollusks, insects, phytoplankton and
zooplankton. Concentrations of copper, for example, are
detrimental to some oysters above 0.1 ppm. Oysters,
cultured in sea water containing 0.13-C.5 ppm of copper,
deposited the metal in their bodies and became unfit as a
food substance.
Lead
Some natural waters contain lead in solution, as much as
98
-------
0.4-0.8 mg/1, where mountain limestone and galena are found.
In the U.S.A., lead concentrations in surface and ground
waters used for domestic supplies range from traces to 0.04
mg/1 averaging about 0.01 mg/1. Lead may also be introduced
into water as a constituent of various industrial and mining
effluents, or as a result of the action of the water on lead
in pipes.
Foreign to the human body, lead is a cumulative poison. It
tends to be deposited in bone as a cumulative poison. The
intake that can be regarded as safe for everyone cannot be
stated definitely, because the sensitivity of individuals to
lead differs considerably. Typical symptoms of advanced
lead poisoning are constipation, loss of appetite, anemia,
abdominal pain, and tenderness, pain, and gradual paralysis
in the muscles, especially of the arms. A milder and often
undiagnosed form of lead poisoning also occurs in which the
only symptoms may be lethargy, moroseness, constipation,
flatulence, and occasional abdominal pains. Lead poisoning
usually results from the cumulative toxic effects of lead
after continuous consumption over a long period of time,
rather than from occasional small doses. Immunity to lead
cannot be acquired, but sensitivity to lead seems to
increase. Lead is not among the metals considered essential
to the nutrition of animals or human beings. Lead may enter
the body through food, air, and tobacco smoke as well as
from water and other beverages. The exact level at which
the intake of lead by the human body will exceed the amount
excreted has not been established, but it probably lies
between 0.3 and 1.0 mg per day. The mean daily intake of
lead by adults in North America is about 0.33 mg. Of this
quantity, 0.01 to 0.03 mg per day are derived from water
used for cooking and drinking. A total intake of lead
appreciably in excess of 0.6 mg per day may result in the
accumulation of a dangerous quantity of lead during a
lifetime. Lead in an amount of 0.1 mg ingested daily over a
period of years has been reported to cause lead poisoning.
The daily ingestion of 0.2 mg lead is considered excessive
by one authority. Lead poisoning among human beings is
reported to have been caused by the drinking of water
containing lead in concentrations varying from 0.042 mg/1 to
1.0 mg/1 or more. There is a feeling that 0.1 mg/1 may
cause chronic poisoning if the water is used continuously,
expecially among hypersensitive persons. For many years,
the mandatory limit for lead in the OSPHS Drinking Water
Standards was 0*1 mg/1; but in the 1962 Standards, the limit
for lead was lowered to 0.05 mg/1. In the WHO International
Standard and WHO European Standards, the limit for lead has
99
-------
been set a 0,1 mg/1. Uruguay has used a standard as low as
0.02 mg/1. several countries use 0*1 mg/1 as a standard.
Traces of lead in metal-plating baths will affect the
smoothness and brightness of deposits. Inorganic lead salts
in irrigation water may be toxic to plants. In the culture
of oats and potatoes, lead nitrate in concentrations of 1.5
to 25 mg/1 had a stimulating effect, but at concentrations
over 50 irg/1 all plants died in a week's time. Lead at a
concentration of 51,8 rrg/1 of nutrient solution was slightly
injurious to sugar beets grown in sand culture. Germination
of cress and mustard seeds in solution culture was
completely inhibited by a 2760 mg/1 lead solution, during an
exposure period of 18 days. Germination was delayed and
growth was retarded by 345-1380 mg/1 of lead.
Farm animals are poisoned by lead from various sources,
including paint, mere frequently than by other metallic
poison. It is not unusual for cattle to be poisoned by lead
in the water; the lead need not necessarily be in solution,
but may be in suspension. Chronic lead poisoning among
animals has been caused by 0.18 mg/1 of lead in soft water.
Chronic changes in the central nervous system of white rats
were observed after an ingestion of 0.005 mg of lead per kg
of body weight. Most authorities agree that 0.5 mg/1 of
lead is the maximum safe limit for lead in a potable supply
for animals.
The toxic concentration of lead for aerobic bacteria is
reported to be 1.0 mg/1; for flagellates and infusoria, 0.5
mg/1. The bacterial decomposition of organic matter is
inhibited fcy 0.1 to 0.5 mg/1 of lead. In water containing
lead salts, a film of coagulated mucus forms, first over the
gills, and then over the whole bcdy of the fish, probably as
a result of a reaction between lead and an organic
constituent of mucus. The death of the fish is caused by
suffocation due to this obstructive layer. In sof-fc water,
lead may be very toxic; in hard water equivalent
concentrations of lea<3 are less toxic.
Selenium
Analogous to sulfur in many of its chemical combinations,
selenium is used in its elemental form and as several salts
in a variety of industrial applications, such as
pigmentation in paints, dyes, and glass production; as a
component of rectifiers, semiconductors, photo-electric
cells, and other electrical apparatus; as a supplement to
sulfur in the rubber industry; as a component of alloys; and
for insecticide sprays. Selenium occurs in some soils as
100
-------
basic ferric selenite, as calcium selenate, as elemental
selenium, and in organic compounds derived from decayed
plant tissue. In some areas of South Dakota and Wyoming,
soils may contain up to 30 mg/kg of selenium. Selenium may
be expected in trace quantities in the municipal sewage from
industrial communities.
Proof of human injury by selenium is scanty and definite
symptoms of selenium poisoning have not been identified; but
it is widely believed that selenium is highly toxic to man.
It has been stated that the symptoms of selenium poisoning
are similar to those of arsenic poisoning. Mild chronic
selenium poisoning has been observed in humans living in
areas where the soil and produce are rich in selenium. In
addition, there have been cases of selenosis at industrial
establishments that use or produce selenium compounds.
Selenium in trace amounts appears to be essential for the
nutrition of animals, including man, although very little is
known about the rcecbanism of its action. Arsenic and
selenium are apparently antagonistic in their toxicity,
tending tc counteract each other. Selenium salts are
rapidly and efficiently absorbed from the gastro-intestinal
tract and excreted largely through the urine. Retention is
highest in the liver and kidney. Surveys have shown that
dental caries rates of permanent teeth were significantly
higher in seleniferous areas than in non-seleniferous areas.
There is also a tendency for increased malocclusion and
gingivitis in seleniferous areas. The USPHS Drinking Water
Standards have restricted selenium to 0.05 mg/1 on a
mandatory basis for many years. In 1962, however, the new
standards lowered the mandatory limit to 0.01 mg/1. The WHO
International and European Drinking Water Standards
prescribe a mandatory limit of 0.05 mg/1. These strict
standards were undoubtedly set because of the similarity
between arsenic and selenium poisoning, the dental effect,
and the known toxicity to livestock, as described below.
In general, the soil in parts of the world where selenium
poisoning occurs naturally contains 1 to 6 mg/kg of selenium
in the 'top eight inches. However, plants vary in their
ability to absorb selenium; the final selenium
concentrations in the plant will be determined by many
factors, including the species and age of the plant, season
of the year, and the concentration of soluble selenium
compounds in the root zone.
Selenium poisoning ("alkali disease" or "blind staggers")
occurs frequently among livestock in the Great Plains
regions of the United States and Canada, and also in Mexico.
It can be produced in laboratory rats, as well as livestock.
10-1
-------
by feeding abnormal amounts or inorganic selenium compounds
of selenif^rous feed. Selenium poisoning occurs naturally
among cattle, sheep, horses, pigs, and even poultry, in both
chronic and acute forms. It is characterized by loss of
hair from mane and tail and soreness of the feet, as well as
by deformity, loss of condition, and emaciation. Among
poultry, the eggs give rise to abnormal or weak chicks.
Impairment of vision, weakness of limbs, and respiratory
death have resulted from livestock feeding on plants
containing 100 to 1000 mg/kg of selenium.
Added as a sodium selenite, 2.0 mg/1 of selenium has been
toxic to goldfish in eight days, and lethal in 18 to 46
days. Minute concentrations of selenium appear not to be
harmful to fish during an exposure period of several days;
however, constant exposure to traces of selenium has caused
disturbances of appetite and equilibrium, pathological
changes, and even deaths of fish after several weeks.
Concentrations considered safe for human beings over a
period of weeks have been toxic to fish.
Zinc
Occurring abundantly in rocks and ores, zinc is readily
refined into a stable pure metal and is used extensively for
galvanizing, in alloys, for electrical purposes, in printing
plates, for dye-manufacture and for dyeing processes, and
for many other industrial purposes. Zinc salts are used in
paint pigments, cosmetics, Pharmaceuticals, dyes,
insecticides, and other products too numerous to list
herein. Many of these salts (e.g., zinc chloride and zinc
sulfate) are highly soluble in water; hence it is to be
expected that zinc might occur in many industrial wastes.
On the other hand, some zinc salts (zinc carbonate, zinc
oxide, zinc sulfide) are insoluble in water and consequently
it is to be expected that some zinc will precipitate and be
removed readily in most natural waters.
In zinc mining areas, zinc has been found in waters in
concentrations as high as 50 mg/1. In most surface and
ground waters, it is present only in trace amounts. There
is some evidence that zinc ions are adsorbed strongly and
permanently on silt, resulting in inactivation of the zinc.
Concentrations of zinc in excess of 5 mg/1 in raw water used
for drinking water supplies cause an undesirable taste which
persists through conventional treatment. Zinc can have an
adverse effect on man and animals at high concentrations.
102
-------
In soft water, concentrations of zinc ranging from 0. 1 to
1.0 mg/1 have been reported to be lethal to fish. Zinc is
thought to exert its toxic action by forming insoluble
compounds with the mucous that covers the gills, by damage
to the gill epithelium, or possibly by acting as an internal
poison. The sensitivity of fish to zinc varies with
species, age and condition, as well as with the physical and
chemical characteristics of the water. Some acclimatization
to the presence of zinc is possible. It has also been
observed that the effects of zinc poisoning may not become
apparent immediately, so that fish removed from zinc-*
contaminated to zinc-free water (after 4-6 hours of exposure
to zinc) may die 48 hours later. The presence of copper in
water may increase the toxicity of zinc to aquatic
organisms, but the presence of calcium or hardness may
decrease the relative toxicity.
Observed values for the distribution of zinc in ocean waters
vary widely. The major concern with zinc compounds in
marine waters is not one of acute toxicity, but rather of
the long-term sub-lethal effects of the metallic compounds
and complexes. From an acute toxicity point of view,
invertebrate marine animals seem to be the most sensitive
organisms tested. The growth of the sea urchin, for
example, has been retarded by as little as 30 ug/1 of zinc.
Zinc sulfate has also been found to be lethal to many
plants, and it could impair agricultural uses.
Oil _and .Grease
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or
other plankton. Deposition of oil in the bottom sediments
can serve to prohibit normal benthic growths, thus
interrupting the aquatic food chain. Soluble and emulsified
material ingested by fish may taint the flavor of the fish
flesh. Water soluble components may exert toxic action on
fish. Floating oil may reduce the re-aeration of the water
surface and in conjunction with emulsified oil may interfere
with photosynthesis. Water insoluble components damage the
plumage and coats of water animals and fowls. Oil and
in a~~ water — can — resui% — in — t&e _ formation of
objectionable surface slicks preventing the full aesthetic
enjoyment of the water.
Oil spills can damage the surface of boats and can destroy
the aesthetic characteristics of beaches and shorelines.
103
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This is not. a processing constituent, but is used for
lubrication of stripping plates in primary copper refineries
and in lubricating various components of copper casting
machinery and associated conveyers. Raw waste values for
oil and grease in primary smelter effluents were found to be
insignificant. One primary refinery value was quite high.
Rationale for Re-jection of Other_Waste Water
Constituents as Pollutant Parameters
Dissolved Solids
In natural waters the dissolved solids consist mainly of
carbonates, chlorides, sulfates, phosphates, and possibly
nitrates of calciurc, magnesium, sodium, and potassium, with
traces of iron, manganese and other substances.
Many communities in the United States and in other countries
use water supplies containing 2000 to 4000 mg/1 of dissolved
salts, when no better water is available. Such waters are
not palatable, may not quench thirst, and may have a
laxative action on new users. Waters containing more than
4000 mg/1 of total salts are generally considered unfit for
human use, although in hot climates such higher salt
concentrations can be tolerated; whereas, they could not be
in temperate climates. Waters containing 5000 mg/1 or more
are reported to be bitter and act as bladder and intestinal
irritants. It is generally agreed that the salt
concentration of good, palatable water should not exceed 500
mg/1.
Limiting concentrations of dissolved solids for fresh-water
fish may range from 5,000 to 10,000, mg/1, according to
species and prior acclimatization. Some fish are adapted to
living in more saline waters, and a few species of fresh-
water forms have been found in natural waters with a salt
concentration of 15,000 to 20,000 mg/1. Fish can slowly
become acclimatized to higher salinities, but fish in waters
of low salinity cannot survive sudden exposure to high
salinities, such as those resulting from discharges of oil-
well brines. Dissolved solids may influence the toxicity of
heavy metals and organic compounds to fish and other aquatic
life, primarily because of the antagonistic effect of
hardness on metals.
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Waters with total dissolved solids over 500 mg/1 have
decreasing utility as irrigation water. At 5,000 mg/lr
water has little or no value for irrigation.
Dissolved solids in industrial waters can cause foaming in
boilers and interference with cleanliness, color, or taste
of many finished products. High contents of dissolved
solids also tend to accelerate corrosion.
Specific conductance is a measure of the capacity of water
to convey an electric current. This property is related to
the total concentration of ionized substances in water and
water temperature. This property is frequently used as a
substitute method of quickly estimating the dissolved solids
concentration.
From the standpoint of quantity discharged, dissolved solids
could have been considered a pollutant parameter. However,
there is no readily available treatment for significantly
decreasing dissolved solids beyond the levels achieved by
the limitations on metals content and pH. Energy
requirements, especially for evaporation, are such as to
preclude limiting dissolved solids at this time. Operators
should, however, be encouraged to minimize discharge of
excessive dissolved solids by intelligent management of
those plant operations resulting in the contribution of
additional dissolved solids to the waste effluents.
Sulfate
Sulfate may constitute a large fraction of the dissolved
solids. Sulfuric acid is a major byproduct of copper
smelting and losses are inevitable. Sulfuric acid is also
the electrolyte for copper refining, from which there are
occasional losses.
The only practical treatments are total impoundment or
evaporation to a solid. Because of the cost availability of
these technologies, treatment of sulfate is regarded as
beyond the scope of the "best available" or "best
practicable" criteria under the Act.
Chloride
Many of the copper plants on tidewater use seawater as one
source of water, and numerous outfalls will contain seawater
as one component of the effluent. Under these
circumstances, chloride concentration limitations would
105
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have no meaning. Except for these special cases, chlorides
will not be found in copper industry waste effluents in
significant quantities.
Other Metals
Iron and nickel are two metals that will be readily
detectable in all but a very few waste solutions from
primary copper operations. However, establishment of
effluent guidelines on copper and cadmium, as well as on pH,
will insure that these metals are at comparably low
concentrations, and specific guidelines are not necessary
for these two metals. Tellurium is omitted primarily
because of a lack of data, not only on its concentration in
untreated effluents, but also on effective treatment methods
and the effluent concentrations which result from such
methods. Tellurium tends to concentrate in electrolytic
refinery slimes, and is present in only low concentrations
in most other effluent streams.
Alkali metals and alkaline earths will be found in nearly
all effluent streams, sometimes in high concentrations.
Sodium will be present in many streams as a result of
saltwater inclusion, or the use of Na2CO3 or NaOH for
neutralization or pH adjustment, and calcium and/or
magnesium will be found in any stream which has been limed.
Chemical Oxygen Demand
The chemical oxygen demand is a measure of the quantity of
the oxidizable materials present in water and varies with
water composition, temperature, and other functions.
Dissolved oxygen (DO) is a water quality constituent that,
in appropriate concentrations, is essential not only to keep
organisms living but also to sustain species reproduction,
vigor, and the development of populations. Organisms
undergo stress at reduced DO concentrations that make them
less competitive and able to sustain their species within
the aquat ic environment. For example, reduced DO
concentrations have been shown to interfere with fish
population through delayed hatching cf eggs, reduced size
and vigor of embryos, production of deformities in young,
interference with food digestion, acceleration of blood
clotting, decreased tolerance to certain toxicants, reduced
food efficiency and growth rate, and reduced maximum
sustained swimming speed. Fish food organisms are likewise
affected adversely in conditions with suppressed DO. Since
all aerobic aquatic organisms need a certain amount of
106
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oxygen, the consequences of total lack of dissolved oxygen
due to a high COD can kill all inhabitants of the affected
area.
If a high COD is present, the quality of the water is
usually visually degraded by the presence of decomposing
materials and algae blooms due to the uptake of degraded
materials that form the foodstuffs of the algal populations.
The low concentration of oil and grease found in the process
waste waters of this industry will minimize the organic
sources of COD. Limitations on pH will control ferrous-iron
content of effluents.
Cyanide
Cyanides in water derive their toxicity primarily from
undissolved hydrogen cyanide (HCN) rather than from the
cyanide ion (CN~). HCN dissociates in water into H+ and CN~
in a pH dependent reaction. At a pH of 7 or below, less
than 1 percent of the cyanide is present as CN-; at a pH of
8, 6.7 percent; at a pK of 9, 42 percent; and at a pH of 10,
87 percent of the cyanide is dissociated. The toxicity of
cyanides is also increased by increases in temperature and
reductions in oxygen tensions. A temperature rise of 10°C
produced a two- to threefold increase in the rate of the
lethal action of cyanide.
Cyanide has been shown to be poisonous to humans; amounts
over 18 ppm can have adverse effects. A single dose of
about 50-60 mg is reported to be fatal-.
Trout and other aquatic organisms are extremely sensitive to
cyanide. Amounts as small as 0.1 part per million can kill
them. Certain metals, such as nickel, may complex with
cyanide to reduce lethality especially at higher pH values,
but zinc and cadmium cyanide complexes are exceedingly
toxic.
When fish are poisoned by cyanide, the gills become
considerably brighter in color than those of normal fish,
owing to the inhibition by cyanide of the oxidase
responsible for oxygen transfer from the blood to the
tissues.
While cyanides are used in the concentrating of copper ores
by flotation, they are not used in copper smelting or
refining, nor are they formed by any of the processing
operations, and no need exists for cyanide limitations.
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Temperature is one of the most important and influential
water quality characteristics, temperature determines those
species that may be present; it activates the hatching of
young, regulates their activity, and stimulates or
suppresses their growth and development; it attracts, and
may kill when the water becomes too hot or becomes chilled
too suddenly. Colder water generally suppresses
development. Warmer water generally accelerates activity
and may be a primary cause of aquatic plant nuisances when
other environmental factors are suitable.
Temperature is a prime regulator of natural processes within
the water environment. It governs physiological functions
in organisms and, acting directly or indirectly in
combination with other water quality constituents, it
affects aquatic life with each change. These effects
include chemical reaction rates, enzymatic functions,
molecular movements, and molecular exchanges between
membranes within and between the physiological systems and
the organs of an animal.
Chemical reaction rates vary with temperature and generally
increase as the temperature is increased. The solubility of
gases in water varies with temperature. Dissolved oxygen is
decreased by the decay or decomposition of dissolved organic
substances and the decay rate increases as the temperature
of the water increases reaching a maximum at about 30°C
(86°F). The temperature of stream water, even during
summer, is below the optimum for pollution-associated
bacteria. Increasing the water temperature increases the
bacterial multiplication rate when the environment is
favorable and the food supply is abundant.
Reproduction cycles may be changed significantly by
increased temperature because this function takes place
under restricted temperature ranges. Spawning may not occur
at all because temperatures are too high. Thus, a fish
population may exist in a heated area only by continued
immigration. Disregarding the decreased reproductive
potential, water temperatures need not reach lethal levels
to decimate a species. Temperatures that favor competitors,
predators, parasites, and disease can destroy a species at
levels far below those that are lethal.
Fish food organisms are altered severely when temperatures
approach or exceed 90°F. Predominant algal species change,
primary production is decreased, and bottom associated
organisms may be depleted or altered drastically in numbers
108
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and distribution. Increased water temperatures may cause
aquatic plant, nuisances when other environmental factors are
favorable.
Synergistic actions of pollutants are more severe at higher
water temperatures. Given amounts of domestic sewage,
refinery wastes/ oils, tars, insecticides, detergents, and
fertilizers more rapidly deplete oxygen in water at higher
temperatures, and the respective toxicities are likewise
increased.
When water temperatures increase, the predominant algal
species may change from diatoms to green algae, and finally
at high temperatures to blue-green algae, because of species
temperature preferentials. Blue-green algae can cause
serious odor problems. The number and distribution of
benthic organisms decreases as water temperatures increase
above 90°F, which is close to the tolerance limit for the
population. This could seriously affect certain fish that
depend on benthic organisms as a food source.
The cost of fish being attracted to heated water in winter
months may be considerable, due to fish mortalities that may
result when the fish return to the cooler water.
Rising temperatures stimulate the decomposition of sludge,
formation of sludge gas, multiplication of saprophytic
bacteria and fungi (particularly in the presence of organic
wastes) , and the consumption of oxygen by putrefactive
processes, thus affecting the esthetic value of a water
course.
In general, marine water temperatures do not change as
rapidly or range as widely as those of freshwaters. Marine
and estuarine fishes, therefore, are less tolerant of
temperature variation. Although this limited tolerance is
greater in estuarine than in open water marine species,
temperature changes are more important to those fishes in
estuaries and bays than to those in open marine areas,
because of the nursery and replenishment functions of the
estuary that can be adversely affected by extreme
temperature changes.
Temperature is an indicator of unusual thermal loads where
waste heat is rejected from a process. Excess thermal
loads, even in noncontact cooling operations, have not been
and are not expected to be a significant problem in the
copper industry. In most fresh-water operations, the
cooling water is used in closed circuit with a cooling pond
or cooling tower; in seawater applications, where a once-
109
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through scheme is used, flows are so large that temperature
rise is insignificant.
110
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
Introduction
The control and treatment technologies that are currently
being used, or have anticipated application, for reducing
the discharge of pollutants in the process waste water
sources of the primary copper industry, including acid plant
blowdcwn, contact cooling water, slag granulation,
electrolytic refining, and miscellaneous sources, are
discussed in this section. The discussion includes a range
of treatment alternatives for each type of waste water
stream. Alternative control technologies that could limit
or eliminate the effluent originating from the various
sources are identified.
In the context of this report the term "control technology"
refers to any practice applied in order to reduce the volume
of waste water discharged. "Treatment technology" refers to
any practice applied to a waste water stream to reduce the
concentration of pollutants in the stream before discharge.
Water usage at either a primary copper smelter or refinery
can be very complex. Some integrated sources exist which
use large volumes of water for milling of ore to produce
concentrates, for noncontact cooling of pyrometallurgical
equipment, and for process. The process uses include slag
granulation; acid plant blowdown; contact cooling for
fire-refined copper, anode copper, shot copper, and various
forms of cathode copper; refinery wastes, such as spent
electrolyte, electrolytic refinery washing, and slime
recovery; and miscellaneous sources, such as DMA plant
blowdown-and purge, slurry overflow from dust collection
systems and wet fluid-bed charge systems, arsenic plant
washdown, general plant washdown, and byproduct scrubbers,
such as for rhenium recovery from molybdenum roaster
offgases. Some sources may have large ancillary operations
on-site, which produce waste waters not attributable to this
discussion. Often these waste waters are either partially
or entirely commingled prior to treatment, discharge,
recycle, or reuse. Storm water runoff is not a problem at
some sites, but at others it is one of the most complicating
factors.
Much of this industry, primarily due to physical location,
employs judicious control practices with very little, if
111
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any, discharge of process waste water. Most of the
remaining facilities are currently striving toward
maximization of waste water control and application of new
treatment facilities. Many of these technologies have been
studied and are discussed in the remainder of this section.
Control Technology
The primary copper industry, because of its integrated and
pyrometallurgical operations, has numerous possibilities for
control of process waste waters. Refineries, with no
on-site associated smelting operation, do not have all of
these possible alternative control approaches available.
Slag Granulation
Reverberatory furnace slag is conventionally loaded into
rail cars or pots and transported to the slag waste area.
Two disposal methods are generally used, slag dumping and
slag granulating. With the former, the rail car or pot is
tipped and the contained slag is discharged, or "pancaked".
After air cooling, the slag becomes a hard material,
composed almost entirely of insolubles. This material, at
any later date, can be crushed and sized for application as
road surfacing material, as one example. With the other
technique, slag granulating, the slag is poured from the
rail car or pot into a high-velocity jet of water. The
nearly instantaneous result is a finely divided and
evenly-sized rock, which has excellent application as a
concrete agglomerate or road surface material.
Of the 15 currently operating primary copper smelters, 11
perform slag dumping, while the four remaining smelters
practice slag granulation. Since slag dumping is a dry
operation, there are no process waste waters produced. One
of the smelters, which practices granulating, reuses all of
its slag granulating water in its copper concentrators as
part of the floatation media. No discharge of process waste
water results from this ccntrol practice. Another smelter
using this wet practice, collects all of the granulating
water in its mill tailings pond. All of this water is then
recycled to the slag granulation operation, used for on-site
irrigation, or lost through solar evaporation or seepage.
The third plant completely recirculates from its granulation
water clarification pond with a resultant no discharge of
process waste water. The last slag granulation-practicing
smelter collects this waste water in a slag granulation pond
on a once-through basis, and then discharges the overflow
from this pond. Thus, as illustrated in Table 31, only one
of the 15 currently operating primary copper smelters has a
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TABLE 31. SLAG GRANULATION WATER CONTROL AND TREATMENT PRACTICES
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICES
TOO,
101,
102,
105,
106,
107,
109,
in,
112,
113,
114
no
108
103
104
> All waste to dump. No water used,
All water directly reused in mill concentra-
tor circuit.
No discharge.
Collected in tailings, recycled and reused
for irrigation, evaporation, and seepage.
Small
discharge
936,000
GPD
Most of water is recycled, small amount to
tailing ponds. Eventual ( 5 miles of ponds)
discharge. See Code 1002, below.
Collected in granulation pond on once-through
basis. Pond overflow discharged.
1002**
When new plant replaces old facility (fall, 1975)
see Code 103, above, small discharge will
be eliminated by slag dumping.
looor
1003
Waste to dump. No discharge.
1001**
1004**
Slag to mill for copper content recovery
No slag produced. Hydrometallurgical
facility.
**New facility currently under construction.
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discharge of process waste water pollutants from slag
granulation.
Of the five primary copper smelters currently under
construction, one is hydrometallurgical, three plan to
employ slag dumping or will continue to slag dump, and the
fifth plans to mill its slag because of its high copper
content. The resultant product will be a copper concentrate
and will be recycled to the process.
Identification of Control Alternatives.
Conversion to .Slag Dumping. One domestic copper smelter
recently discontinued its slag granulating practice in an
effort to reduce its total plant process waste water volume.
The slag is currently dumped and used as fill. It can be
crushed to marketable sizes, if desired. This control
technique completely eliminates this source of process waste
water.
Recycle. If available retention time is provided for
cooling, the slag granulation water may be recycled. The
main criteria for the recycle of granulating water is
temperature. If pondage area or capacity is not available,
a cooling tower or heat exchanger is a practical approach.
Reuse. The reuse of slag granulating water as a part of the
floatation mill water is currently practiced by two
smelters. No effects in the percentage of recovered copper
have been noticed by this practice. In commingling its slag
granulation waste water with other plant waters, one of
these two smelters also uses this water for on-site
irrigation, as well as any and all other water-demanding
practices. Some is also lost to evaporation.
Acid Plant Slowdown
After subjecting a hot gas stream to a "hot" electrostatic
precipitatcr for primary particulate removal and before
converting the effluent to sulfuric acid in a metallurgical
sulfuric acid plant, final gas stream cleaning and
conditioning must be performed. Conventionally, an open
scrubbing tower and a packed scrubbing tower (or one
scrubber performing both operations of preconditioning and
scrubbing), and a mist precipitator (for final particulate
and SO3 removal) are used. Due to a buildup in salts, such
as chlorides of lead, in the scrubbing water, a blowdown,
termed acid plant blowdown, must be drawn from the circuit.
This process waste water has a highly acidic pH and is
contaminated with trace metal ions.
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Table 32 is presented to indicate the current and
anticipated control and treatment technologies for acid
plant blowdown. Of the 11 currently operating copper
smelters which have metallurgical sulfuric acid plants and
the associated precleaning and preconditioning equipment,
seven have no current discharge of acid plant blowdown, two
anticipate no discharge of process waste water pollutants
through control practices (one as an interim approach), and
the remaining three will discharge after treatment (one of
the three is currently attempting no discharge through
reuse). Five of the seven plants with no current discharge
reuse this blowdown in either the floatation or leaching
circuits of their integrated smelters. Four of the smelters
are either already at no discharge or are planning no
discharge through the usage of the blowdown effluent as a
preconditioner of hot gas streams or as a feed blending
material.
Of the five smelters, which are currently under construction
or replacement, one will be a hydrcmetallurgical operation
and will not operate an acid plant, one plans to use solar
evaporation to achieve no discharge, one currently plans no
SO2 control from its new electric furnace, one will
recirculate its blowdown in its concentrator circuit, and
the last plans to treat the blowdown from a new sulfuric
acid plant prior to discharge.
Identification, of control Alternatives.
Reuse. Some integrated and custom smelters are located in
water deficient areas and employ water reuse schemes best
practicable to their situation. Other smelters, either
through anticipation of future water pollution regulations
or through compliance efforts of existing regulations, are
or will be applying schemes to either minimize or completely
eliminate this process waste water source.
One such control method has been the collection of this
process waste water in either the copper milling tailings
pond or tailings thickener underflow, with subsequent
release to the tailings pond. This pond, containing many
commingled sources of mill and smelter water, is the source
of water on a recirculated basis for numerous plant
operations, such as in the floatation circuit. There is a
possibility of minor recovery loss of copper through this
practice. Mills located in extremely arid locales must use
all available water, even at the expense of some recovery
loss. The quantitative value of this recovery loss has not
been documented and is assumed to be extremely small. One
currently operating domestic smelter, which has mining and
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TABLE 32. ACID PLANT SLOWDOWN CONTROL AND TREATMENT PRACTICES
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICE
100
101
102
0*
109
107
114
106
113
104
Slowdown neutralized with Mnonla and used to
precondition converter gases prior to hot
ESP. No discharge.
2/3 of blowdown to reverb brick flue spray
chamber for cooling reverb gases, other
1/3 used to precondition converter gases
prior to hot ESP. Any excess Is solar
evaporated on slag dunp.
No discharge.
Blowdown from packed tower used In open tower.
Open tower blowdown to clarlfler. One-half
recycled to packed tower, other half to
two-stage annonla neutralization facility.
Then 35 GPM to converter hot ESP for gas
preconditioning and 10 GPM to R and R hot
ESP for gas preconditioning (joins 10 GPM
DMA purge). No discharge anticipated.
Blowdown to tailings pond. Pond water
reclrculated to mill concentrator.
No discharge.
Blowdown from new scrubbers and Mist preclplta-
tors to recycle and tailings thickener
underflow. No discharge.
Slowdown used In mill concentrator circuit.
No discharge.
Blowdown to settling pond and either recycled
or wasted. No discharge.
Blowdown to add ponds and reused In copper
precipitation leach facility.
No discharge.
Blowdown currently used to blend fluid-bed
roaster feed. Anticipate closed circuit.
but will eventually send to proposed
treatment facility.
*Ant1c1pated, practice under construction.
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TABLE 32.(cent)
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICE
103
no
1000**
1003
0.9
GPD
800-3,000
6PM*
Slowdown to lime pond, then to tailings ponds,
Eventual ( 5 miles of ponds) discharge.
Slowdown to go to new treatment facility
with subsequent discharge.
Slowdown to evaporation pond.
No discharge.
Slowdown to thickener, overflow reused,
sludge possibly sold.
No discharge.
11 fax Plumy currently undtr construction.
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floatation circuits on-site, plans to treat all of its acid
plant blowdown in a newly-constructed facility (discussed
later). Once this system is in operation, the smelter
operators will attempt to recycle some of the treated
effluent back to the floatation circuit. Current data,
developed through a bench-scale study, indicate that a
recycle practice could result in some loss in copper
recovery. Current plans at this smelter call for the
discharge of this treated effluent.
The reuse of this acidic waste as part of the leach
precipitation solution is practiced fcy one domestic smelter,
with the end result being cement copper.
Pyrometallurgical smelters, whether custom or integrated,
are heat producing operations. Much of this heat is
collected by waste heat boilers, physically located in-line
with hot gas streams. Even with waste heat boilers, a
demand for additional gas stream cooling usually exists at
many smelters. Often, water is injected into effluents as
they pass through brick flues and balloon flues on their way
to hot electrostatic precipitatcrs. One smelter reuses most
of its acid plant blowdown, as discussed in Table 32, by
spraying part of this effluent into the reverberatory
furnace brick flue spray chamber. The remainder is used as
an electrostatic precipitator preccnditioner, as discussed
further in this text, and any excess is disposed of through
solar evaporation.
Besides its application as a cooling medium for hot smelter
offgases, the acid plant blowdcwn has also found application
as a gas stream preconditioner prior to entrance into hot
electrostatic precipitators. As discussed in the above
paragraph, one currently-operating smelter disposes of part
of its acid plant blowdown by injection into its converter
gas stream just prior to primary dust removal. Introducing
this acidic waste before a hot electrostatic precipitator
tends to increase the particulate collection efficiency.
Smelter operators have indicated that if the SO3 content of
the hot gas stream is too high, the introduction of the
acidic waste stream will reduce particulate collection
efficiency in the electrostatic precipitator. Thus, ammonia
neutralization facilities have been added to reuse systems,
so that pH adjustment of the acid plant blowdown could be
maintained and SO^ offgas content could, in turn, be held at
optimum concentration for best collection efficiency. One
other smelter is also neutralizing its blowdown with ammonia
and using this controlled pH solution for converter gas
conditioning prior to its hot electrostatic precipitator. A
third smelter, which is currently lining-out a new
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dimethylaniline (DMA) plant, plans to blend its DMA purge
and preconditioning blowdown from its DMA scrubber and mist
precipitator equipment with its conventional acid plant
blowdown (discussed under DMA purge control). The current
blowdown from the existing acid plant is only 2.5 gpm and,
along with the 20 gpm from the DMA plant purge will be used
to precondition the hot roaster and reverberatory furnace
offgases prior to the electrostatic precipitator. Smelter
operators anticipate nc discharge of process waste water
pollutants from acid p^ant blowdown by application of this
technique, but final proof of this anticipation will shortly
be forthcoming.
One possible limitation to this approach could be a buildup
of acid plant blowdown pollutants, (such as salts of lead,
etc.) in the offgas system. This problem would not exist
for smelter offgases which are released to the atmosphere
after hot gas collection in an electrostatic precipitator.
Since conventional SO2 control systems are not used 100
percent of the operating time, an atmospheric bleed of the
waste water pollutants is possible. Many of these
pollutants are collected as particulate in the hot
electrostatic precipitator and are either recycled on-site
or shipped to other facilities for further processing.
One smelter is reusing its acid plant blowdown by blending
it with feed materials to its fluid-bed roaster, which is
operated on a wet-charge basis (other fluid-bed roasters
used by the existing copper smelting industry are dry feed
operations). It was the smelter operator's intent that all
acid plant blowdown water could be disposed of in this
manner, but this control practice has not been achieved to
date. Currently, a small volume of effluent not used is
discharged. Future plans at this smelter are to treat its
acid plant blowdown and discharge this treated effluent.
Methods for Minimizing Acid Plant Slowdown Volume. The
volume of the acid plant blowdcwn is controlled principally
by the buildup of pollutants in the scrubbing media, and in
some cases, by the media's temperature. By using
highly-efficient primary particulate control devices, the
particulate load carried to the pre-acid plant scrubbers and
mist precipitators will be minimized; thus, minimizing the
required blowdown. Effective heat exchangers and cooling
towers on the recirculating scrubber waters will provide
sufficient cooling, so that blowdown, due to cooling
requirements, will fce negated.
Contact Cooling Water
This industry employs large volumes of water for both
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noncontact cooling and contact cooling. In contact cooling,
intermediate and finished products are both sprayed and
quenched with water to not only solidify the item, but also
to produce required surface characteristics.
When blister copper is cast into cakes, surface
characteristics are not important, and the casting is
conventionally sprayed with water, most of which is consumed
through evaporation, and then allowed to air cool. When the
final product is fire-refined copper, the castings are
subjected to direct cooling with water. This is also the
situation with shot copper cooling; wherein, molten copper
is allowed to flow over a screen. As the copper falls
through the mesh of the screen, it is immediately quenched
in a tank of water, forming a shot product. Most copper
production is centered around the manufacturing of an
intermediate product, anode copper, which is subsequently
used in the electrolytic production of cathode copper. As
the anodes are poured into an anode casting contained on a
continuous casting wheel, direct contact water is used as
both a spray and a complete immersion media. The equipment
conventionally used for complete immersion is called the
Bosh Tank. When cathode copper is poured in the desired
casting shapes, such as cakes, and wire-bars, the direct
contact of water is used to achieve both cooling and the
required surface characteristics.
Some primary facilities may have several copper casting
operations, depending upon the products produced on-site.
As an example, a smelter could produce anode copper, which
would require a Bosh Tank for cooling. If this same smelter
also has an on-site electrolytic refinery, direct contact
cooling systems must also be required for the casting of
cathode shapes.
Table 33 illustrates the current cooling practices of this
industry, as well as the current and anticipated control and
treatment practices for this process waste water source.
Data reviewed during this study indicate that 22 direct
contact cooling operations are used by the 15 currently
operating primary smelters (including four smelters with
on-site refineries). These 22 operations include four
cathode-shape c ooling operations, 11 anode casting
facilities, two fire-refined copper casting operations,
three blister cake operations, and two shot copper cooling
facilities. Of the 22 operations, 14 are currently
operating at no discharge of process waste water pollutants,
two anticipate no discharge, four discharge continuously.
120
-------
TABLE 33. CONTACT COOLING WATER CONTROL AND TREATMENT PRACTICES
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICE
102
0*
0*
Anode casting: water In closed circuit with
cooling tower, cooling tower blowdown
joins blowdown from wire-bar casting
cooling tower blowdown, entire blowdown
to side-stream filter, anticipate total
water recycle.
Cathode (wire-bar) casting: water 1n closed
circuit with cooling tower, cooling tower
blowdown joins blowdown from anode casting
cooling tower, anticipate total water
recycle.
110
200-500
GPM*
111
106
Anode casting: water directly reused 1n mill
concentrator circuit. No discharge.
Cathode-shape casting: water to go to new
treatment facility with subsequent
discharge.
Anode casting: water collected in mill tailings
thickener, all flow recycled (with some
evaporation) to mill concentrator.
No discharge.
Cathode-shape casting: water in closed circuit
with cooling tower, blowdown to tailings
pond, with recycle to process.
No discharge.
Blister cake cooling: air cooled with some
water spray; spray water totally recycled
from cooling pond.
No discharge.
Anode casting: water 1n closed circuit with
cooling tower, water added to cooling tower
as make-up. No discharge.
Cathode-shape casting:
No discharge.
water in closed circuit.
*Anticipated, practice under construction.
121
-------
TABLE 33. (cont.)
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICE
105
107
101
Intermit-
tant
Fire-refined (cathode)-shape casting: water
mostly recycled, with small intermittent
discharge.
Fire-refined casting:
overflow recycled.
water to thickener,
No discharge.
109
113
114
100
103
Anode casting: water in closed circuit with
cooling tower, blowdown to evaporation
pond. No discharge.
Anode casting: water in closed circuit with
cooling tower, blowdown reused in mill
concentrator. No discharge.
Anode casting: water to tailings thickener,
reused in mill concentrator. No discharge,
Anode casting: water all used in mill
concentrator circuit. No discharge.
Anode casting: water in closed circuit with
100 percent circulation.
No discharge.
1.9KD
112
285 GPM
7 GPM
Anode casting: water collected In slag
settling pond, part is recirculated for
slag granulation (14 MGD). Remainder
( 1.5 MGD) discharged to tailings ponds.
Eventual (5 miles of ponds) discharge.
Anode casting: once-through water, part used
for shot copper cooling, remainder
discharged.
Shot copper cooling:
discharged.
once-through water,
122
-------
TABLE 33. (cont.)
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICE
104
-"90,000
GPD
(2,000 GPM,
45 min/da
108
1000**
1003**
Shot copper cooling: Intermittent flow, all
discharged. Plan to treat water in proposed
treatment facility with anticipated
discharge.
Blister cake cooling: air cooled, no water
discharged.
Blister cake cooling: water consumed during
spraying and air cooling.
No discharge.
Anode casting: water will be in closed
circuit with cooling tower, blowdown
to evaporation pond.
No discharge.
Retain existing cooling facilities
No discharge.
** New facility currently under construction.
123
-------
and two discharge intermittently. Two of the discharging
operations plan to treat their contact cooling water
effluents prior to discharge.
All three of the blister cake cooling operations are
basically performed by air cooling. Any water involved is
contained in closed circuit with no discharge of process
waste water pollutants. Both shot cooling operations are
currently discharging, while only one of the two currently
operating fire-refined copper casting facilities is
intermittently discharging. Nine of the eleven anode
casting operations are (or anticipate being) at no
discharge, with one almost at complete recycle and the other
operating on essentially a once-through basis. Three of the
four cathode-shape casting operations are already, or
shortly hope to be, at no discharge of process waste water
pollutants.
Plans for contact cooling water for the five on-site
replacement or new smelters include, as shown in Table 33,
no discharge from one anode casting facility by virtue of a
cooling tower and evaporation pond and retainment of
existing cooling facilities for the other four facilities.
For the seven electrolytic refineries, which are not
contained on-site within a primary copper facility, the
common control practice is recycle after collection and
cooling in either a cooling pond or cooling tower, with some
discharge. One refinery located in the Southwest has no
discharge of process waste water pollutants by virtue of an
evaporation pond with nearly 100 percent recycle. The
current control practices for contact cooling water for
these seven refineries are shown in Table 34.
Identification of Control Alternatives.
Minimizing Volumetric Flow Rate. The most important
operating parameter for the cooling water used by this
industry is temperature. If a means for cooling this
process waste water source to the required temperature is
not provided, a large bleed would be required with the
maximum bleed being once-through cooling water. The best
method of minimizing this "temperature" bleed is to provide
sufficient circuit cooling. This can best be accomplished
through the use of cooling ponds and cooling towers. Eight
of the 22 cooling operations currently in practice are, or
will shortly be, using cooling towers. A narrative of these
eight operations is presented in Table 33. The blowdown
from these towers is disposed of by various means such as
disposal to the tailings pond (with subsequent reuse),
124
-------
TABLE 34. ELECTROLYTIC REFINERY WASTE WATER CONTROL
AND TREATMENT PRACTICES
PLANT
CODE
DISCHARGE
CONTROL AND/OR TREATMENT PRACTICES
115
116
117
118
Bleed
S t re am
Yes
Bleed
S tream
Yes
Yea
CASTING: Recycled through cooling
pond, bleed discharged.
CATHODE WASH: Last rinse formerly
discharged, now recycled
SPENT ELECT: Black acid sold.
SLIMES REG: Waste effluents combined,
neutralized and discharged
CASTING: Recycled through cooling pond
bleed discharged.
CATHODE WASH: Recycled to electrolyte,
SPENT ELECT: Acid returned to tank
house, Ni S04 recovered
wi th vacuum evaporator.
SLIMED REC: Sent elsewhere for process
ing.
BARO. COND: Once through cooling water
on Ni S04 evaporator baro-
metric condenser, discharge
Bleed | CASTING: Re cycled through cooling pond,
Stream bleed discharged.
CATHODE WASH: No data.
0 SPENT ELECT: Acid returned to tank
house.
SLIMES REC: Process waste liquors
diluted and discharged,
Yes CASTING: Once through , all discharged,
CATHODE WASH: No data.
125
-------
TABLE 34. (cont.)
PLANT
CODE
DISCHARG
CONTROL AND/OR TREATMENT PRACTICES
119
120
-121
Yes
Bleed
Discharg*
SPENT ELECT: Evaporated to produce
CuS04 , solution stripped
of Cu and sent elsewhere
for processing.
SLIMES REC: Sent elsewhere for
pro cessing.
CASTING: Partially recycled, balance
discharged.
CATHODE WASH: No data.
SPENT ELECT: NiSOA recovered with
vacuum evaporator,
black acid sold.
SLIMES REC: Sent elsewhere for
processing.
CASTING: Recycled to evaporation pond,
some used for crop irrigation.
CATHODE WASH: No data.
SPENT ELECT: Evaporated in lined pond.
SLIMES REC: Sent elsewhere for
processing.
CASTING: Recirculated, 10Z bleed
filtered and discharged
CATHODE WASH: Consumed in CuS04
crystalllzation plant
SPENT ELECT: Returned to tank house,
Ni too low to recover.
SLIMES REC: Sent elsewhere for
processing.
126
-------
TABLE 34. (cont.)
PLANT
CODE DISCHARGI
CONTROL AND/OR TREATMENT PRACTICES
102*
110* 0
111*
106* 0
100?'
CATHODE WASH: Returned to cells.
SPENT ELECT: Evaporated and Hi
recovered, acid recycled
to tank house.
SLIMES REC: Sent elsewhere for
processing.
CATHODE WASH: Returned to cells
SPENT ELECT: Through cementation
cells, acid to evapora-
tion pond. Anticipate
treating in new treat-
ment facility.
SLIMES REC: Scrubber and process
was tewater to evaporation
pond. Anticipate treat-
ing in new treatment
facility.
CATHODE WASH: Returned to cells.
SPENT ELECT: Discharged to tailing
area.
SLIMES REC: Sent elsewhere for
pro cessing.
CATHODE WASH: Returned to cells
SPENT ELECT: No data.
SLIMES REC: Sent elsewhere for
processing.
No discharge anticipated for all
pro cess was tewater sources.
*Casting dis cussed in previous table,
**Under construction.
127
-------
evaporation pond, or reuse in the mill concentrator. One
smelter collects its anode casting water in its slag
settling pond. Because of the large volume of this pond,
most of the cooling water is recirculated, with only a very
small discharge.
Reuse. Several smelters either use their contact cooling
water directly in the mill concentrator circuit or first
pass it through a thickener and then use the overflow in
this circuit. One facility uses most of its contact cooling
water for slag granulation; another smelter uses a small
portion of its anode casting water for shot copper cooling.
Recycle, in some geographical locations, once-through usage
of water had, at one time, been condoned, based principally
on water availability. With more emphasis placed upon the
minimization of process waste water generation, recycle
becomes very important. As pointed out previously, the
usage of cooling towers and cooling ponds affords a very
practical approach to recycle. Commingling of some cooling
waters with other process waste waters, even though they may
not be the subject process waste waters of this industry
subcategory, may provide sufficient cooling so that recycle
from this commingled effluent is possible. Recycle is
prevalent at most of the electrolytic primary copper
refineries not located on-site with a smelter.
Refinery Wastes
Spent Electrolyte- As shown in Table 34, spent electrolyte
is an effluent which has commercial value. NiSOf*, CuSO4,
and black acid are all recoverable byproducts from this
effluent. At some refineries, the spent acid as returned to
the tank house for reuse. One primary refinery uses solar
evaporation and an impoundment area to dispose of its spent
electrolyte. Currently, there are no known discharges of
spent electrolyte.
Electrolytic Refinery Washing. When the cathodes and the
spent anodes are removed from the electrolytic cell,
adhering acid is rinsed off. The general practice used at
the primary copper refineries is to use all of this water as
electrolyte make-up. One plant consumes this effluent in
its copper sulfate crystallization plant. Disposal to the
tailings ponds with subsequent plant reuse is the practice
at one smelter-refinery combination. Currently, there are
no known discharges of electrolytic refinery washing water.
Slimes Recovery. Gold and silver are recovered at only
three of the eleven existing refineries. The other eight
128
-------
ship -their slimes elsewhere for precious metal recovery.
The process waste water produced during slimes recovery is
very small in volume and generally results as a bleed from
offgas scrubber applications and mother liquors, control
technologies for this process waste water source are
unknown, except for the possible spraying of waste effluents
in the hot o f f gases fr om the Dore f urnace. Treatment
technologies are applicable to this process waste water
source.
NiSOj Vacuum Evaporators. When the decopperized solution
of electrolyte is evaporated in a vacuum evaporator to
crystallize out NiSO4, a barometric condenser may -be used.
These condensers require large volumes cf cool water, and,
characteristically, once-through cooling water is used if
ample quantities are available. Though theoretically only
water vapors pass over the condenser, liquid entrainment,
due to undersized or poorly-designed evaporators, can occur.
This produces a source of process waste water. control
technologies for this source include conversion to a
closed-circuit with the use of a cooling pond or cooling
tower, conversion from a vacuum evaporator to an open
evaporator, and the application of efficient mist
eliminators with proper operating and maintenance
procedures.
Miscellaneous Sources
DMA Plant Slowdown and Purge. DMA plant blowdown is defined
as the mandatory effluent purged from the scrubbers and mist
precipitators used to precondition the gas stream prior to
entrance into the DMA scrubbing tower. The DMA purge is
defined as that volume of water removed from the DMA
stripping tower as a purge in order to maintain salt levels
in recirculating flows.
Three of the fifteen currently operating primary copper
smelters employ DMA systems to concentrate SO2 gas streams
for the production of liquid SO£. All three DMA plant
blowdown effluents have been discussed previously in this
section under acid plant blowdown. One plant currently
takes all of its scrubber blowdcwn and uses most of it for
fluid-bed wet feed blending. This same plant anticipates
the treating of this flow in a proposed treatment facility.
The second smelter collects its blowdown (Plant 114) and
uses it in its mill concentrator circuit with no discharge
of process waste water pollutants.
The third smelter, which is currently in the start-up phase
of its new DMA facility, will have a blowdown and a purge
129
-------
from these facilities. As noted in Table 32, the blowdown
from the packed -tower will be used in the open tower. The
open tower blowdown will proceed to a clarifier. About one-
half of the clarified liquor will fce recycled to the packed
tower, while the other half will proceed to a two-stage
neutralization facility. After the correct pH adjustment
with ammonia has been made, this effluent will be split with
approximately 35 gpm to be used as a gas preconditioner
prior to the hot converter gas electrostatic precipitator.
The remaining sirall flow will join the DMA purge (10 gpm)
and acid plant, blowdown (2.5 gpm) and will be used to cool
the hot roaster and reverberatory furnace gases prior to the
electrostatic precipitator.
The first smelter uses activated carbon to reduce the DMA
concentration in its purge effluent and then discharges this
treated effluent, while the second smelter collects this
purge in its tailings pond and subsequently reuses this
water in its mill concentrator circuit with no discharge.
As stated in the above paragraph, the new DMA system at the
third smelter will attempt no discharge of its purge {10
gpm) by commingling with some DMA plant blowdown and acid
plant blowdown and using this flew for cooking the roaster
and reverberatory furnace gases prior to the hot
electrostatic precipitator.
Identification of Control Alternatives.
Reuse. Reuse of the DMA plant blowdown is exactly similar
to the reuse control practices discussed under acid plant
blowdown. The DMA purge process waste water effluent is
currently being reused in the mill circuit of one smelter by
virtue of commingling effluents. Another smelter plans to
completely reuse its DMA purge (10 gpm) for cooling the
roaster and reverberatory gases prior to the hot gas
electrostatic precipitator,
Minimizing Volumetric Flow Rate. The new DMA facility,
currently in start-up, will have a very low DMA purge flow
rate of 10 gpm. Smelter operators state that the use of
sulfurous acid, in lieu of sulfuric acid, in the DMA
scrubbing tower greatly reduces this purge volume. As with
acid plant blowdcwn, DMA plant blowdown volume can be
reduced by the use of highly efficient primary particulate
removal equipment, so that the blowdown volume will not be
highly dependent on particulate concentration.
Slurry overflow from Dust Collection Systems
and Wet Fluid-Bed Roaster Charge Systems.
Particulate matter collected by cyclones, electrostatic
130
-------
precipita-tors, balloon flues, as well as other particulate
collection devices, is often blended with water. Normal
practice in the primary copper industry is to use just
enough water to complete the blending operation with no
resultant discharge of process waste water.
One currently operating primary copper smelter wet-blends
its fluid-bed roaster charge. Currently, this smelter
reports a discharge of process waste water pollutants from
this blending operation. The water used for blending is
acid plant and DMA plant blowdown, and the smelter operators
are attempting to use this entire effluent for blending.
The resultant discharge is that excess volume which can not
be used. Normal practice would be to use just enough water
to complete the wet blending operation with no resultant
discharge of process waste water pollutants.
Arsenic__Plant Washdown. One currently operating primary
copper smelter produces arsenic trioxide as a byproduct. A
typical hygiene practice at this facility is the vacuuming
and washing-down of contaminated areas. The resultant
effluent from this washdown is discharged, but the smelter
operators plan to combine this effluent with other "dirty"
plant effluents and use this volume to cool the roaster and
reverberatory furnace offgases prior to the hot gas
electrostatic precipitator.
General Plant Washdown. Various sections of a primary
copper facility are hosed-down on a regularly-scheduled
basis or after spills. Primary copper refineries normally
collect this effluent and either recirculate it or use it as
electrolytic make-up water.
Bypro.duct Scrubbers. One known application of a scrubber on
a byproduct molybdenum roaster offgas, used for the recovery
of rhenium, is a closed-circuit operation.
Storm Water Runoff, segregating process waste water
effluents from storm water runoff is the first step normally
taken by smelter operators to reduce the flow volume from
this source. Some plants have built dams at higher
elevations in order to minimize the passage of storm water
runoff onto plant property. The use of curbing is an
excellent control practice for minimizing the commingling of
runoff with process waste waters. Liming retention ponds to
minimize infiltration of spring water should also be
practiced.
131
-------
Treatment. Technology
Neutralization_and Precipitation
In the primary copper smelting and refining industry, most
process waste effluents are acidic, so that neutralization
implies the addition of an alkali. The alkali of choice is
generally lime (CaO) for a number of reasons. The first and
foremost is its low cost and availability, A large primary
copper operation, using hundreds of tons of lime per day in
the concentrator plant, will often find it economically
attractive to manufacture lime rather than purchase it,
further lowering the cost. Caustic soda (NaOfi) and soda ash
(Na^CO^) are possible substitutes, but both of these are
more costly alkalies, and both are currently in short
supply. Also, neither forms an insoluble sulfate, so
neutralization with these alkalies does nothing for sulfate
concentrations. Ammonia (NH3), an alkali easy to handle and
convenient to use in automatic neutralization systems, does
not precipitate copper, but forms a soluble complex with it.
Also, addition of nitrates to receiving bodies of water is
not currently recommended, in view of the deleterious
effects associated with them; they are themselves
pollutants.
While there is no "typical" copper waste stream, character-
istically the important waste streams from a copper plant
will contain some sulfuric acid and can have a pH of 2.
Iron will be a prominent contaminant, and there will be
trace-level concentrations of a number of pollutants
associated with copper in copper ores, such as arsenic,
selenium, tellurium, lead, nickel, or zinc.
Addition of a lime slurry ("milk of lime") to such a solu-
tion will precipitate the hydroxides of several of the
metals and will reduce dissolved sulfate concentrations
through the formation of gypsum (CaSO4.2H2O) . (Formation of
gypsum is, in some respects/ a disadvantage. The treated
effluent from such a system can well exist in a condition of
supersaturation with respect to gypsum and can readily
precipitate when conditions are favorable, sometimes
plugging large pipes with surprising rapidity.)
Iron hydroxide is a good flocculant and "collector" for
scavenging other ions from solution, and the formation of
iron hydroxide by the addition of a soluble iron salt to a
solution already basic or to be made basic by the addition
of an alkali is widely practiced, both in the laboratory and
in practice. The addition of ferric chloride, for example.
132
-------
is a standard procedure in the treatment of sanitary wastes.
The natural presence of iron in copper plant effluents
results in percentage removals of some ions by
neutralization and precipitation better than would be
expected in pure chemical systems. Iron may have other
beneficial effects too, although these are difficult to
document in the very complex ionic solutions involved.
In treating an effluent stream, sufficient lime will be
added to raise the pH to 10-11.5 and the dosed stream will
normally fce conveyed to a settling pond to settle out
suspended solids. Upon exposure to the air, carbon dioxide
is absorbed, gradually reducing the pH. If the retention
time in the pond is long enough, this carbonation will
reduce the pH tc 9.5 or below. During this time, the
precipitated solids will be settling out, so that a final
effluent containing less than 10 ppm (10 mg/1) of total
suspended solids (TSS) can be achieved.
Sometimes, some of the solids are colloidal in nature.
Also, if the retention time is not long enough, or if wind
and wave action in the pond stir up the sediments, these
will prevent reaching the desired low TSS. In such
situations another treatment technology can be applied.
There are now available a number of organic polyelectrolytes
which, though costly per pound, are quite effective at very
low concentrations in providing additional flocculation and
clarification.
Achieving a low TSS content is not generally a major problem
in treating effluents from primary copper facilities.
Neutralization, precipitation, and settling should reduce
TSS to satisfactory levels in almost all situations. The
principal problems with untreated effluents from copper
smelters and refineries relate to dissolved metals, most of
which are precipitable as hydroxides, and anions, especially
sulfate. Removal of suspended solids is a problem only with
respect to the removal of these precipitates after
neutralization.
It has long been known that the solubilities of many metal
hydroxides and hydrated oxides are markedly influenced by
pH. Pourbaix (15) has calculated and compiled "Potential -
pH Diagrams" and solubility curves for many elements, based
on theoretical considerations. Curves based on Pourbaix1s
results are shown in Figure 11 for Ag, As, Cd, Cu, Fe, Hg,
Ni, Pb, Te, and Zn. These curves are, of course,
equilibrium curves for pure compounds in simple systems, and
cannot be extrapolated to the complex multi-ion systems of
primary copper waste waters.
133
-------
100
CP
E
^ o.
.Q
.2
o
CO
0.001
0.0001
0.01
Figure 11. Theoretical solubilities of netal ions as a function of pH.
134
-------
While the curves cannot be extrapolated directly to
practical solutions, they do show that there is no single pH
at which minimum concentrations will be achieved for all
elements, and also, that in the pH range of interest (pH 6
to 12) nearly all of the elements pass through a minimum,
most of them in the pH range 9 to 11.
It will be noted that the solubility of tellurium (data are
based on TeO2) increases rapidly with pH and has no minimum
on the alkaline side. Molybdenum shows a similar pattern,
with solubilities too large to plot in this graph. Silver
solubility decreases with increasing pH, reaching a minimum
at pH 12.02, just off the graph. Arsenic has a high solu-
bility plateau (17 g/1) up through pH 9, and increases
rapidly beyond this point. The solubility of mercury is
also constant, over an even wider range (pH 3.04 to 14.88),
and is also so high (47 g/1) that it too does not appear in
the graph.
Fortunately, since mercury is not commonly associated with
commercial copper ores in other than trace levels, its high
solubility at alkaline pH's does not seriously hamper
pollutant-precipitation schemes based on neutralization.
Arsenic is, however, frequently associated with copper (one
copper mineral, enargite, has the theoretical composition
Cu3As5s4) and is commonly found in primary copper plant
waste streams.
Experimental values of metal solubilities as a function of
pH have been presented by Hartinger (16). Data from
Hartinger for several metals are plotted in Figure 12.
Although they differ somewhat from the theoretical values in
Figure 11, including generally having a higher solubility at
a given pH, che general shapes of the curve are similar, and
again suggest that optimum pH's are in the 9 to 11 range.
These data are for simple, pure systems. Solubilities of
mixed systems as a function of pH are not given, but
Hartinger did present the results of one test in which
copper-nickel mixtures at varying ratios were neutralized to
a uniform pH of 8.5 and allowed to equilibrate for 2 hours.
The solubilities after this time were as follows:
Cu:Ni Ratio Cu, mg/1 Hi,_mg/l £H
2:1 0.76 12 8.2
1:1 0.60 15 8.05
1:2 0.32 28 8.2
135
-------
0.01
7 8 9 10
pH (After 2-hr Standing)
Figure 12. Experimentally determined solubilities of metal ions
a function of li.
136
-------
This example is illustrative of the inherent difficulties in
attempting to extrapolate simple system laboratory or
theoretical data to plant waste streams.
Cupric oxide, which forms from the hydroxide, has a minimal
solubility between pH 9.0 and 10.3 according to Stumm and
Morgen (17). Jenkins et al (18) have reported a minimum
solubility of 0.01 mg/1 in that pH range on the basis of
laboratory studies. Theoretical solubility levels are
seldom obtained in actual practice, owing to poor separation
of colloidal precipitates, slew reaction rates, pH
fluctuations, and the effects of other ions in solution,
However^ the above value for ccpper is approximated in the
final limed effluent from the treatment pond of Plant 103 as
shown in Table 35. The volume of this pond is very large
(retention time 60 days), so that pH fluctuations are
minimized, and adequate time is provided for settling.
Information in the literature indicates that cadmium
concentrations can be greatly reduced by precipitation with
lime. Jenkins et al (18) report that freshly precipitated
cadmium hydroxide leaves approximately 1 mg/1 of cadmium in
solution at pH 8, but that this is reduced to 0.1 mg/1 at pH
10. Hartinger shows even lower values, 0.002 mg/1, at pH 11
(Figure 12). High levels of ircn appear beneficial for the
removal of cadmium by liming; evidently cadmium
coprecipitates with iron hydroxide. It has been indicated
that coprecipitaticn with iron hydroxide at pH 8,5 effects
nearly complete removal of cadmium. Evidence for the
beneficial effects of iron has been presented by Marayama,
et al (19) .
Nickel, frequently present in electrolytic refinery process
waste streams, is alsc precipitated by neutralizing with
lime. The nickel hydroxide has a minimum theoretical
solubility of 0.01 mg/1 at pH 10 according to Jenkins et
al. (18) (On the basis of calculations of Pourbaix, Figure
11, the solubility is an order of magnitude lower than
this). Kantawala and Tomlinson have reported the reduction
of nickel concentration from 100 mg/1 to 1.5 mg/1 (pH 9.9)
by the addition of 250 mg/1 of lime. (20) Their data (Figure
13) suggest that nickel removal had reached a plateau under
these conditions.
Upon neutralization, coprecipitation and adsorption may or
may not bring the concentration of a metal below its
equilibrium value for the adjusted pH. Little research has
been published on the effect of such parameters as pH, Eh
(Oxidation potential), noncommon ions, and complexing agents
on the solubilities of the metals found in copper plant
137
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TABLE 35. CONCENTRATIONS OF SELECTED CONSTITUENTS OF ACID PLANT
EFFLUENT STREAMS BEFORE AND AFTER LIMING
Concentrations , mg/1
Copper Smelter 103
Parameter
pH
COD
Dissolved Solids
Suspended Solids
Oil and Grease
Chloride
Sulfate
Arsenic
Cadmium
Copper
Iron
Lead
Mercury
Nickel
Selenium
Tellurium
Zinc
Before
Liming
1.8
-
5000
6.5
490
8.2
0.09
0.12
0.10
0.91
-0.0001
^0.001
-=0.001
< 0.001
13.7
After
Liming
7.1
1050
1.6
795
11.2
0.06
0.09
0.15
0.19
<0.0001
0.26
-=0.001
^0.001
18.9
Zinc Smelter ^a)
Before
Liming
~4.2
8.2
2672
10
3.5
170
3430
0.53
0.38
0.11
10
1.2
0.005
0.30
7.0
513
After
Liming
—8.2
16
4485
249
4.0
170
2200
-=^0.1
^0.02
-^0.02
0.11
0.15
0.004
0.13
1.8
50
(a) Data obtained under EPA Contract No. 68-01-1518.
138
-------
100
90
c
OJ
o
o
o
E
CD
tr
80
70
60
50
40
30
0
|
100 200
Lime Dosage,mg/z
300
Figure 13. Treatment efficiency for nickel rerroval by cherdcal
precipitation with lime.
From Kantawala and Thompson
(20)
139
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waste streams. For this reason, waste water treatment by
neutralization and precipitation (liming and settling) is
largely empirical at the present time, although it is
generally known that the concentration of many metals can be
reduced to low values fcy neutralization, while others are
not dependably reduced.
As noted earlier, one of the prominent waste water streams
in a copper plant is that arising from the acid plant
recovering sulfuric acid from the sulfur dioxide in the gas
streams. Effluents will result from the gas scrubber, often
in substantial volume, and some may also result from the
electrostatic precipitator or other demisting device used to
remove sulfuric acid mist from the acid plant tail gases.
The combined effluent will be acidic, with a pH of 2 or
less, and will contain concentrations of dissolved metals
scrubbed from the gas stream.
Some experimental results of the effect of neutralization
with lime upon acid plant waste streams are available from
the field sampling program for one copper smelter (Table
35). Also shown are similar data obtained for an acid plant
waste stream at a zinc smelter. The terminal effluent pH's
were slightly different, which may explain some of the
differences observed, as the metal solubilities are quite
pH-dependent on either side of the minimum (as illustrated
by Figures 11 through 13). Nevertheless, some general
observations are possible. Cadmium, ccpper, iron, and lead
concentrations all appeared to be reduced in the effluents
to more or less equilibrium values, 0.02 to 0.1 mg/1 for
cadmium and copper, and 0.10 to 0.19 mg/1 for iron and lead.
Small concentrations of arsenic were further reduced,
perhaps by coprecipitation or absorption, but high arsenic
concentrations were unaffected. Mercury concentration was
essentially unaffected. Results for nickel were anomalous.
The picture for selenium was also unclear; although it does
not form an insoluble hydroxide, it's concentration appeared
to be reduced in the zinc plant effluent by liming and
settling. zinc was reduced to a much lower concentration at
a pH of 8.2 when concentrations where high initially, but
actually showed an increase when initial concentrations were
lower.
These above generalizations should be regarded with some
caution, especially in those cases where large changes are
absent, because of the circumstances surrounding the
sampling. In no case were the results obtained by carefully
neutralizing an effluent sample in the laboratory and re-
assaying. Rather, the samples were dynamic ones taken in
operating plants with the objective of measuring changes
140
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across an operation. Since, in many instances, other
streams also entered and left the pool sampled, there were
commonly seme uncertainties that the inlet and effluent
samples were totally and completely comparable. Thus, minor
changes in concentration could have been caused by dilution
by streams either weaker or more concentrated with respect
to some constituents. Where removals of 80 to 95 percent
were observed, it seems reasonable that these can be
explained only by precipitation of an insoluble compound.
Further evidence of the concentrations achieved by a liming
and settling technique are illustrated by the results of
field sampling presented in Table 36. While both of these
streams are combined streams containing effluents from other
operations, they are indicative of terminal concentrations
achieved upon liming and settling. The tailings pond for
Plant 124 (not covered by this study) includes mine water,
waste effluent froir cementation, and very large volumes of
concentrator tailings underflow. A bleed stream having the
composition shown in the first column of the table is
withdrawn from the tailings pond. This effluent runs
downstream and joins the waste streams from Plant 103 for
additional treatment before final release. Waste streams
from Plant 103 include acid plant scrubber water and anode
casting cooling water. The final effluent is, in general,
at somewhat lower concentrations than the initial effluent
from the upstream plant.
The waste effluent concentrations from Plant 105 are shown
in Table 36. These values, which represent both smelter and
concentrator effluents, are low throughout, particularly for
the trace metals. This plant is, however, almost a special
case, since it is processing a very clean ore, with almost
none of the contaminants of the western porphyry ores
present. (Fire refining only is needed to produce a final
product equal to electrolytically refined copper).
One domestic priirary copper smelter is currently conducting
start-up operations on a new treatment facility. This
facility will handle the process waste waters from two
floatation units, all acid plant blowdown, and all
electrolytic refinery waste water. The volumetric flow rate
to this treatment facility will be approximately 68,400 cu
m/day (18 mgd), comprised of about 60,000 cu m/day (11,000
gpm) from the floatation mill, powerplant boiler blowdown
and flyash flush water, and plant sewage; 4,400 to 16,300 cu
m/day (800 to 3000 gpm) from acid plant blowdown, and 1,100
to 2,700 cu m/day (200 to 500 gpm) from electrolytic
refinery process wastes.
141
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TABLE 36. WASTE EFFLUENT CONCENTRATIONS AFTER
LIMING AND SETTLING COMBINED WASTE
STREAMS
Concentrations , mg/1
Outfall From
Outfall From
Outfall From
Tailings Pond Final Treatment Pond Tailings Pond
Plant 124 (a) Plant 103 (a) Plant 105 00
pH
COD
Dissolved Solids 3,
Suspended Solids
Oil and Grease
Sulfate (as S04=) 2,
Cyanide (CJST)
Arsenic
Cadmium
Copper
Iron
Lead
Mercury
Nickel
Selenium
Tellurium
Zinc
(a) Source: Analysis of
(b) Source: RAPP Data
10.0
15.5
380
9.4
0.1
150
0,25
0.85
<0.001
0.01
0.43
0.11
<0.0001
0.09
<0.001
0.05
0.20
field samples
8.8
8.1
875
2.5
0.0
680
0.10
0.73
< 0.001
0.04
0.20
0.17
< 0.0001
<0.001
<0.001
<0.001
0.10
9.8
1.0
1247
14.
<0.1
1.8
< 0.01
0.01
0.08
<0.005
<0.001
0.005
<0.001
142
-------
The acidic wastes of the acid plant blowdown and the
electrolytic refinery are first blended in a mixing box with
the slightly alkaline wastes from the floatation units.
Milk of lime is then added to the commingled flow to raise
the pH to the desired neutralization value. The effluent
then enters a four-section settling box. Rapid settling of
most of the precipitated ions will occur in the first two
chambers. Ferric chloride will be added as needed in the
third chamber to enhance coagulation. Additional
coagulation will result from the addition of a
polyelectrolyte. The flow from the fourth chamber will then
be split, with each half proceeding to one of two large
clarifiers. It is currently planned that the overflow from
the two clarifiers will be discharged. Approximately 36
kkg (40 ton)/day of sludge, by dry weight, will be produced
and will be retained in a 32 ha (80 acre) pond. Influent,
as well as anticipated effluent, data for this new facility
are shown in Table 37. Recirculation of some of the treated
effluent will be attempted.
Chemical Precipitation
As described in the preceding section, neutralization with
lime may not dependably reduce arsenic, lead, mercury,
selenium, and tellurium to minimal values. Dean, et al
(21), have noted that hydroxide precipitation with lime may
be incomplete for cadmium, lead, and mercury, thereby
requiring additional treatment. Ihey suggest use of sulfide
for additional cadmium precipitation. Cadmium sulfide
solubility appears to be pH dependent, according to data
from Seidell (22)* At pH 3, it is 0.112 mg/1, but drops to
1.7 x 10-5 mg/1 at pH 7, and to 1.2 x 10~7 mg/1 at pH 11.
Many of the sulfides have very low solubilities. The
solubility of lead sulfide, like that of cadmium sulfide,
decreases from 0.160 mg/1 at pH 3 to 1.6 x 10~7 mg/1 at pH
11. (22) The solubility of arsenic trisulfide (As2S3) is
low, 0.8 mg/1, and that of arsenic pentasulfide (AS2S5) is
nearly as low, 1.4 mg/1. (22) Curry (23) has reported that
arsenic levels of 0.05 mg/1 are obtainable by the use of
maximum technically feasible waste water treatment methods.
Precipitation as the sulfide at pH 6.7 was recommended.
Selenium, like sulfur, a Group VI A element, does not form
sulfides, but instead forms analogous selenides. Tellurium,
also a Group VI A element, forms tellurides. The chemistry
of these compounds is not well worked out, and no currently
available technologies for treating these two constituents.
143
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TABLE 37. EXPECTED VALUES OF EFFLUENT CONCENTRATIONS
FROM NEW TREATMENT FACILITY (PIANT 110)
Pollutant Combined Flew Into Waste Treatment
Parameter Waste Treatment Plant Plant Discharge
Flow (average),gpn 13,785 13,655
pH 5.5 7.8
TDS,mg/l 3,293 3,644
TSS, mg/1 33.3 11
Chloride,mg/l 1,183 1,306
Cyanide, mg/1 0.49 0.27
Fluoride, mg/1 7.3 6.3
Al, mg/1 1.35 0.27
As, mg/1 9.39 . 1.20
Cd, mg/1 0.22 0.04
Ca, mg/1 213 292
Cr, mg/1 0.08 0.03
Cu, mg/1 4.88 0.71
Fe, mg/1 5.83 0.38
Pb, mg/1 1.59 <- 0.0023
Mg, mg/1 95 86
I'fri, it^/1 0.38 0.11
Ug, mg/1 <0.001 <0.001
Mo, mgA 2.30 2.13
Mi, mg/1 0.04 0.01
Se, mg/1 0.24 0.20
Zn, mg/1 1.93 0.02
Oil and Grease, ng/1 2.9 < 0.1
144
-------
which has been accorded -the necessary high degree of
confidence in their engineering and economic practicability,
are known. On the basis of the data available, it appears
that coprecipitation and adsorption with a lime
precipitation of other bulk constituents may offer the most
practical current technology for reducing selenium
concentrations in effluents.
Sulfide is added either as gaseous hydrogen sulfide or as a
solution of sodium sulfide. Neither are in a cost class
with lime. A recent price for H2S (liquid, sellers tanks,
works) was S0.22/kg ($0.10/lbf, and Na2S, in drums (i.e.,
works) was in the $0.14 to 0.16/kg ($0.0625 to .0725/lb)
range* Polishing of the effluent by sand filtration would
presumably be required. Sulfide precipitation should be
effective for removal of heavy metals, probably as a cleanup
or polishing treatment following a liming and settling
treatment. Some potential disadvantages may be associated
with sulfide treatment. Hydrogen sulfide, a corrosive and
very toxic gas, is difficult to handle. Sodium sulfide is a
more tractable compound, and would probably be preferred for
many applications. Separation of sulfide precipitates from
solutions is not always easy, and filtration might be
required. Overall, sulfide precipitation is unquestionably
a more complicated and expensive treatment than
neutralization and precipitation. It would be most
applicable to the small-volume, highly polluted waste
streams, such as those from acid plants or from refinery
byproduct recovery.
Dalbke (13) describes the use of hydrogen sulfide in Japan
to precipitate copper frcm copper-tearing mine waters. The
water is first passed over a bed of limestone to neutralize
the excess acid and then is allowed to mix with H2S in a
precipitating tank. The slurry is thickened and the under-
flow filtered to recover the copper. The H2S is produced by
injecting a mixture of oil and sulfur into an autoclave
which is then heated. When the reaction temperature is
reached, the reaction is exothermic and goes to completion.
The H2S is stored in a gas holder for use. According to
Dalbke, H2S produced in this way should be competitive with
detinned iron for cementation. H2S has the added advantage
that it produces a raffinate that can be reused as
industrial water. No data are given on the removal of other
ions or on the quality of the effluent overflow from the
thickener, and specific details of the process and its cost
are lacking.
The range of effectiveness of sulfide precipitation in
copper extractive metallurgy is not well known, particularly
145
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Its applicability to precipitation of pollutants not
effectively removed by a lime-and-settle neutralization
technique. As far as is known, treatment with sulfide is
not presently being used in the U. S. nonferrous metals
industry for waste stream treatment, and its engineering and
economic practicability has not yet been demonstrated.
Reverse osmosis
The movement of pure solvent through a semipermeable
membrane into a solution containing the same solvent is
called osmosis. Equilibrium is reached only when the
liquids on each side of the membrane are of the same
composition or sufficient additional pressure is applied to
the solution side to counterbalance the osmotic force.
Application of additional pressure on the solution side
reverses the direction cf osmotic flow and results in
concentration of the solution and migration of additional
pure liquid to the pure liquid side. This is reverse
osmosis.
From this description, it can be seen that reverse osmosis
falls into the category of a waste management technique
rather than being a treatment method. It merely divides a
liquid waste into two fractions, a pure one, suitable for
reuse or recycle, and a residue containing all of the
pollutants originally present, now in a more concentrated
form. Treatment of the concentrated fraction is still
necessary for conversion into some disposable form, with one
exception, that of deep well disposal. Reverse osmosis may
be a useful pretreatment of waste water prior to deep-well
disposal, as discussed in a later section.
There are some significant weaknesses in reverse osmosis.
The most important of these is the susceptibility of the
semipermeable membranes to plugging, blinding, and chemical
attack. Acidity, as well as suspended solids,
precipitation, coatings, dirt, organics, and other
substances can render the membrane inoperative and in some
cases destroy it. Meirbrane life is critical to a practical
economic operation, but is unknown for many systems.
Reverse osmosis has been used for the recovery of metals
from waste plating solutions (24), but a 12 to 20 1/min (3
to 5 gpm) unit is considered a large unit. Reverse osmosis
does not yet appear to be a demonstrated technology for
copper plant waste effluents, nor does it appear likely to
reach this level within the near-term future.
146
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Ion Exchange
Ion exchange, as the -term Is used in the treatment of water
and aqueous solutions, refers to the exchange of one ion in
solution for another in the exchanger. An ion exchanger may
be simply defined as an insoluble solid electrolyte which
undergoes exchange reactions with ions in solution. Most
ion exchangers now are synthetic organic resins. There are
two types, cation exchangers and anion exchangers, each type
removing that particular ion. By using both, water can be
deionized to a purity equivalent to that of distilled water.
After becoming saturated, the ion exchange resins are
normally regenerated with an acid or a base, depending on
whether it is a cation or anion resin.
Some of the disadvantages can be inferred from the above.
Since it is an exchange process, there is no disappearance
of the ions removed from solution; they are merely
temporarily stored on the resin and are liberated again upon
regeneration. In fact, the situation is even worse, since
the necessary excess of regenerant adds to the pollutant
load. The quantity of regenerant, and thus its cost, is
directly proportional to the quantity of ions removed, so
that ion exchange is not economically practical for the
treatment of solutions of high concentration. It is usually
restricted to solutions containing 1 to 4 g/1 or less of
dissolved solids.
Ion exchange is very useful in providing a method of
achieving a high purity water for critical uses, and is
commonly used to deionize feed water for high pressure steam
boilers. It is also useful in recovering certain metals for
their value, and, as described later, a "liquid ion
exchange" method is used to recover copper from leach
solutions.
However, like reverse osmosis, ion exchange falls more into
the category of a waste management technique, rather than
offering a treatment technology for waste effluents. A
possible exception, though there are no confirming data on
the solutions of interest, would be the application of anion
exchange resins to remove anionic complexes from solutions
in which mcst of the pollutants were present as cations.
For example, some recent work by Lindstedt, Houck, and
O'Commor (25) on the removal of trace elements from
effluents from secondary waste water treatment suggests that
selenium is probably present as the anionic complex SeO3~2.
Results of some radiotracer tests at low concentrations
(<0.01 rag/1) indicated that selenium was poorly removed by a
147
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cation resin, but almost quantitatively by an anion resin.
How effective anion exchange might be on the relatively high
ionic-strength waste solutions frcm copper plants needs to
be demonstrated experimentally. Anion exchange has been
strikingly successful in recovering uranium, which also
forms an anionic complex, UO2(SO4)3~*, from dilute sulfuric
acid solutions.
Evaporation
Evaporation removes the water from a solution, leaving a
solid residue. When this can be done by solar evaporation,
it is perhaps the ideal treatment technique for waste
effluents. Costs are low, and energy demands are virtually
nil.
Except for solar evaporation, evaporation as a means of
treating aqueous wastes has very limited application, for
several reasons. The energy costs are high, even when
multiple-effect evaporators are used for the removal of most
of the water. Taking the concentrated solution from an
evaporator to dryness usually requires a dryer, and thus the
expenditure of more energy. The final product, though dry,
is still water soluble, so that its ultimate disposal
presents problems in insuring that it is not redissolved.
Evaporation to dryness is used for the treatment of some
radiochemical wastes, but this is a rather specialized
application with a very different value rating on unit
costs.
Evaporation to eliminate waste effluents may have some
application in the copper industry, where waste heat can be
utilized for evaporation and the resultant solid pollutant
is suitably disposed of. For example, some polluted water
streams could perhaps be evaporated by the heat in molten
slag, with any residue going to the slag pile with the slag.
The sensible heat in furnace stack gases can be used to
evaporate moderate volumes of water; the residue in these
gases will primarily return to the process. These
approaches are discussed in more detail under the control
section of this discussion.
Conversion to a Solid
Conversion of a waste effluent solution or sludge to a solid
is one treatment method for the elimination of the discharge
148
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of pollutants, some silicates are known to form solids; one
of the best known is portland cement. There are also some
proprietary compounds, ,the chemical nature of which has not
been disclosed, which are used to convert liquids and
slurries to a solid form. One such system is reputed to
convert a solution or slurry to a solid in a gelation period
of from 24 to 72 hours, after which the waste can go to a
landfill. (24) This system, as it is normally used,
reportedly reacts with polyvalent metal ions to produce
stable, insoluble, inorganic compounds. Monovalent cations,
many organic compounds, many anions, water, and colloidal or
high molecular weight rraterials may not enter into the
reaction, but are physically entrapped in the solid matrix.
Extensive data on the fixation achieved by this system are
not available. The results of one simple leach test are
illustrative. In this test, 25 g of fixed waste from a
refinery byproducts solution bleed (Se + Te recovery
operation) were leached by recirculating 250 ml of water (pH
7.3) over the waste contained in a Euchner funnel for 4 days
(96 hr) . Analyses of the solution at the end of this period
indicated the following removals from the fixed waste:
.Ions Leached, uq/g material (ppm)
_p_H__ As Cd _Cu Fe .Pb__ Se Te Zn_
10.3 >0.08 C.015~ 1.1 1.05 0.75 ~Q^33>o760 1.6
Since costs for this fixation treatment are estimated to run
between $0.005 and $0.025/1 ($0.02 and $0.10/gal), it is not
one to be applied indiscriminately tc large volumes of waste
effluents. It should be applicable to low volume, highly
polluted waste streams, such as those from refinery
byproducts recovery operations, where the waste stream may
involve only a few thousand liters per day. Prior reduction
of the volume to be treated, by reverse osmosis, ion
exchange, or evaporation, may be a useful adjunct to fixa-
tion as a solid.
Deep Well Disposal
Disposal of wastes, especially oil field brines and chemical
wastes, in deep wells is becoming increasingly popular as
restrictions on discharging wastes to navigable waters
become tighter. Such wells can be costly, especially when
several are needed and depths are one or two thousand
meters, as sometimes is required. Geologic conditions must
149
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be suitable, and in many parts of the country, deep wells
are not practical. Sand strata at depth, especially those
already naturally saline, are airong the most suitable
candidates for deep well disposal.
As far as is known, no primary copper operation is using
deep well disposal.
Carbon Adsorption
Adsorption on carbon is one of the appropriate treatments to
remove organic wastes from a waste stream. Since there are
very few organic wastes associated with the primary copper
industry, carbon adsorption is little used. It has been
reported that carbon is being used to strip dimethylaniline
. (DMA) from polluted purge stream arising out of the use of
DMA scrubber on metallurgical offgases. The carbon bed may
be regenerated by burning off the adsorbed organic, and then
returned to service.
Skimming and Flotation
Oil is generally removed from waste water by passing the
water through a lagoon or through a series of inverted
weirs; the oil floats to the top and is skimmed off.
Granular absorbents may be used to assist in the collection
and removal of the oil. Air flotation can also be used to
aid in the agglomeration and separation of the oil phase,
though there are nc known applications of flotation cells
for this purpose in the primary copper industry.
150
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SECTION VIII
COSTS, ENERGY, AND NONWATER QUALITY ASPECTS
Introduction
This section deals with the costs associated with the
various control and treatment strategies available to the
primary copper industry. In addition, other nonwater
quality aspects are discussed.
Basis for Cost Estimation
Data on capital costs and on annual operating costs for
present control and treatment practices were obtained from
selected primary copper operations. These data were
modified in the following way to put all costs on a common
basis:
(1) The capital costs reported were changed
to 1971 dollars by the use of the
Marshall and Swift Index (quarterly values
of this index appear in the publication
Chemical Engineering, McGraw Hill).
(2) The annual costs were recalculated to
reflect common capitalized charges. To
do this, the annual costs were calculated
by using a factor method as follows:
Operating and maintenance - as reported
by the copper smelters and refineries.
Depreciation - 5 percent of the 1971
capital,
Administrative overhead - U percent of
operating and maintenance.
Property tax and insurance - 0.8 percent
of the 1971 capital.
Interest - 8 percent of the 1971 capital.
Other - as reported by the smelters and refineries
Economics of Present Control and
Treatment Practices
Discussed below are cost data presented by selected primary
copper operations:
151
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Plant 102
"~~~ T
Operations at this plant include the conventional
pyrometallurgical smelting steps of roasting (multiple-
hearth) , smelting (reverberatory furnace), and converting.
The blister copper produced from this operation is cast into
anode copper and electrolytically refined. The final
product, cathode-shape copper, is shipped as wire bar and
billet copper. All copper concentrates consumed are
purchased (i.e., this primary smelter is defined as a custom
smelter). A metallurgical sulfuric acid plant converts
about 20 percent of the convertor operation's SO2 to H2SO4,.
The remainder of this strong SO2 offgas is converted into
liquid SO2 by means of a newly constructed dimethylaniline
plant* A byproduct As2Q3 plant/ located within the smelting
complex, handles flue dusts from the roasters and
reverberatory furnaces. Electrolytic slimes are dried and
fired in a Dore furnace, and the byproduct Dore metal is
shipped out for final metal recovery. Bleed electrolyte is
first subjected to electrowinning for copper recovery, and
then evaporated to produce byproduct NiSO<£. This plant is
also geographically located in an area of high
precipitat ion.
Sources of process waste water at this plant include (or did
include):
Acid plant blowdown
DMA plant purge
Anode casting contact cooling water
Cathode-shape contact cooling water
Reverberatory furnace slag quenching water
Spent electrolyte
Dore furnace scrubber water
Arsenic plant washdown water
Contaminated storm water rmv-off commingled with
process waste water.
RAPP data, which is now outdated, indicated a total of five
outfalls for both process and nonprocess waste water with a
total flow of 44,627 cu m/day (11.8 mgd). Detailed
technical descriptions of the control and internal treatment
practices which have been undertaken and incorporated into
the production scheme at this plant have been presented in
several of the sections of this development document.
Tabulated below are the cost data submitted by company
personnel on capital investment, which will effectively
"close" all water circuits at this facility. Annual costs
are estimated.
152
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Capital_Costs _ 1971_$
(1) The complete recycle and reuse of
dimethylaniline purge $ 79,000
(2) The complete recycle and reuse of
acid plant blowdcwn (all corrosive-
proof materials) $ 469,000
(3) Fine-casting (cathode-shape)
cooling tower $ 263,000
(4) Anode casting cooling tower $ 284,000
(5) Recycle of noncontact reverb and converter
thermal jacket water for temperature control $ 474,000
Total $1,569,000
The actual installed cost totalled $1,640,000. This amount
included the installation of side-stream filters for both
the fine casting and anode casting cooling towers. The
side-stream filter permits the recycle of a five percent
cooling tower purge by returning this volume, after solids
removal, to the cooling system. Discarding the capital
costs for the recirculation of noncontact cooling water
(number (5) above) , which is not covered by the effluent
limitations of this document, the total capital cost is
$1,095,000. This value is equivalent to $10.06/annual kkg
($9. 13/annual ton) of copper.
Annual_Costs _ $/vear
Operating and maintenance 236,000
Administrative overhead 9,000
Depreciation 78, 000
Interest 125,000
Property tax and insurance _ 12,000_
Total 460,000
$/kkg ($/ton) 4.22 (3.83)
Plant no
Plant 110 is an integrated copper smelter with an on-site
copper refinery. This smelter is currently conducting
start-up operations on a new treatment facility. The
technology used in this treatment facility is basically lime
and settle and has been described in detail in section VII
of this document. Sources of waste water and flow rates
follow:
Flow rate
source cu m/day (gpm)
Floatation mill, power plant
toiler blowdcwn, plant sewage 60,000 (11,000)
Acid plant blowdown 4,400-16,300 (800-3,000)
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Electrolytic refinery
Total
1^100-2^700
J2GO-500)_
65,500-79,000 (12,000-14,500)
Total Treatment Plant
Capital Costs
Control building and equipment
Waste treatment facilities (mix
tank and clarifiers)
Pumping and piping
Pump stations and pipe lines
Lime plant (expansion of existing one)
Miscellaneous
Total
Annual Costs
Operating and maintenance
Depreciation
Property tax and insurance
Interest
Total
1971 $
$ 193,000
669,000
550,000
1,070,000
275,000
321,000
$3,078,000
$/year
468,000
207,000
60,000
257,000
$ 992,000
Since this treatment plant handles the process waste waters
from sources additional to those covered by the effluent
guidelines for this document, the flow rate ratio of
"smelter plus refinery to total" is used for allocating
several of the above cost factors. For the remaining
factors, marked by "*", a 0.5 allocation ratio is used.
This ratio is based upon the emphasis of neutralizing the
low pH of the process waste water sources of the acid plant
blowdown and refinery in lieu of the magnitude of volume
(i.e., the pH of the other "higher volumetric flow rate"
waste water sources is much higher).
Allocation of costs to smelter and refinery:
Capital Costs
Control building and equipment
Waste treatment facilities (mix
tank and clarifiers)*
Pumping and piping
Pump stations and pipe lines
Lime plant (expansion of
existing one)*
Miscellaneous
Smelter and Refinery TOTAL
$/Annual kkg ($/Annual ton)
1971 $
$ 46,000
334,000
132,000
258,000
138,000
77^000
$985,000
4.15 (3.79)
154
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Annual Costs I/year
Operating and maintenance* 115,000
Administrative overhead 2,000
Depreciation 18,000
Interest 29,000
Property tax and insurance 3TOOQ
Smelter and Refinery TOTAL ~167,000
$/kkg ($/ton) 0.70 (0.64)
Economics of Additional Control
and Treatment Practices
The domestic primary copper industry is currently composed
of 23 existing facilities. Statistics relevant to the
economic analysis contained in the discussion to follow are
presented below:
Primary copper smelting subcategory:
Number of existing sources 16
Number with smelting facilities only 12
Number with smelting facilities and
on-site refineries 4
Number currently complying tc, or very
near, proposed effluent limitations 11
Number required to employ additional
control and treatment technology 5
Primary copper refining sufccategory:
Number of existing sources (one to close,
but is being replaced) 7
Number currently complying tc, or very
near, proposed 1977 effluent limitations 4
Number currently complying to, or very
near, proposed 1983 effluent limitations 3
Number required to employ additional control
and treatment technology for EPCTCA 3
Number required to employ incremental control
and treatment technology for BATEA 3
The economics of the necessary additional control and
treatment practices for the nine priirary copper facilities
not currently at, or very near, compliance are discussed in
the ensuing paragraphs.
Plant 103
This facility is a primary copper smelter which is
155
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integrated with several off-^site mining and milling
operations, as well as one on-site milling plant. There is
no electrolytic refining conducted on-site. Anode copper is
cast and shipped to a company-owned refinery about 150 miles
away. Currently, a large amount of reuse and recycle is
practiced at this smelter, and the anode casting water is
nearly in closed-circuit. Slag granulation will shortly be
discontinued, and slag dumping will be practiced. The one
remaining process waste water source, acid plant blowdown,
is currently passed through a lime pit and then commingled
with other effluents in a large series of ponds.
Two approaches are suggested for this smelter's acid plant
blowdown. The first approach is to pump the acid plant
blowdown to the plant1s integrated mill floatation unit,
lime it at the mill to raise its pH, and then introduce it
into the floatation circuit as input water. Since the
smelter's operation is not solely dependent upon this mill,
a second approach should be employed as an alternative.
This second approach requires cascading the acid plant
blowdown first to the plant's venturi scrubber and then to
the gas stream conditioning scrubber, which should reduce
the blowdown volumetric flow rate, and then use the blowdown
as a gas stream cooling media prior to the smelter's new
baghouse. This approach will allow the total consumption of
the blowdown, and the baghouse will be able to collect
essentially all of the metals contained in the blowdown.
Cost estimates for these two approaches are as follows:
QlEital_Costs 1971 $
Pump blowdown to mill for reuse
(Approach 1} 164,000
Reverse cascade and use as baghouse
cooling media (Approach 2) 246,000
Total 410,000
$/Annual kkg ($/Annual ton) 2.24 (2.03)
Annual Costs $/year .
Approach 1 (while Approach 2 is
implemented) 25,000
Approach 2 61,000
Total 86,000
$/kkg ($/ton) 0.47 (0.42)
Plant 104
This primary copper facility is integrated with a copper-
zinc-iron sulfide ore mine, an ore beneficiation facility.
156
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an iron ore smelting plant, and a chemical complex.
Locating the battery limits of the facility, for the
purposes of these recommended effluent limitations, at a
point just prior to the commingling of pyrite and copper
smelting offgases indicates that two process waste water
effluents must be controlled. These two streams are the
copper shotting effluent, about 125 I/sec (2,000 gpm) for 45
min/day duration, and the slag granulation effluent,
approximately 123 I/sec (1,950 gpm) for eight hours/day
duration.
A suggested approach to meet no discharge of process waste
water pollutants to navigable waters is to reuse the copper
shotting water (cascade) in the slag granulation circuit by
means of a cooling pond. Any necessary blowdown from this
pond for soluble salts build-up,- if one is even necessary,
can be used along with the acid plant blowdown as fluid-bed
roaster concentrate slurry. The approximate costs for this
approach are:
Capital Costs 12ZLJL
Cooling pond and cascade system 51,000
$/Annual kkg ($/Annual ton) 3.73 (3.39)
Annual Costs $/year
Cooling pond and cascade system 10,000
$/kkg ($/ton) 0.73 (0.67)
This smelter produces fire-refined copper and is integrated
with a mining and milling operation. Casting wheel cooling
water is reused as part of the mill's floatation water
requirement. The only process waste water discharge from
the smelting operation is periodic in nature and results
during clean-out of settled bone ash from the fire-refined
copper cooling tank. One approach to achieve no discharge
of process waste water pollutants would be to place this
volume of cooling water (about 200,000 gallons) in a holding
tank during bone ash clean-out. Ihe economics of this
approach follow:
Capital Costs 1971 $
Holding tank 7,000
$/Annual kkg ($/Annual ton) 0.11 (0.10)
157
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Annual Costs . j/year
Nominal 2rOOO
$/kkg ($/ton) 0.03 (0.03)
Plant 110 is priirary copper smelter with an on-site
electrolytic refinery, and is integrated with a mine-mill
complex. Smelter and refinery acidic process waste waters
currently join mining, milling, and power plant effluents in
a newly-constructed lime and settle treatment facility. The
resultant clarified effluent is discharged. One approach
recommended for compliance to a no discharge of process
waste water pollutant limitation at this facility would be
to reuse the smelter-refinery portion of the treated plant
process waste water effluent as milling floatation water.
The costs of such an approach, including the pumping and
piping of this effluent for a distance of two miles to the
mill, are as follows:
Capital Costs 1971 $
Reuse smelter and refinery treated
waste water 410,000
$/Annual kkg ($/Annual ton) 1.74 (1.58)
Annual Costs $/year
Total 103,000
$/kkg ($/tOn) 0.44 (0.40)
£lant_V12
This primary copper smelter produces anode and shot copper.
Currently, the only process waste water discharge at this
facility is from the shot and anode casting cooling
operations.
One scheme available for this plant would be to install a
cooling pond with the required cooling capacity. If
necessary, a ten percent blowdown could be taken from this
cooling pond and evaporated by solar means. The economics
of such an approach are as follows;
Capital Costs 1971 $
Cooling pond 6,000
158
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Evaporation pond for 10% blowdown
(lined) 328^000 _.
Total 334,000
$/Annual kkg ($/Annual ton) 2.61 (2.37)
Annual Costs $/year
Cooling pond 1,000
Evaporation pond 82,000.
Total 83,000
$/kkg ($/ton) 0.64 (0.59)
Plant_VI6
This is a primary copper refinery not located on-site with a
primary copper smelter, and is thus a constituent of the
primary copper refining subcategory. Currently, the process
waste water discharge to navigable waters is about 570 cu
m/day (105 gpm) and is primary contact cooling water from
primary metal casting. Barometric condensers are operated,
but de-intrainment devices are provided. Based upon a fine-
casting production rate of 145,000 kkg (160,000 tons)/year,
the flow value calculates out to be 1,340 1/kkg (328
gal/ton), which is well below the recommended value of 2,000
1/kkg (480 gal/ton). Effluent data for this plant indicate
high TSS concentration values. Thus, one recommended method
to comply to the 1977 proposed limitations is to clarify the
plant's process waste water prior to discharge. The costs
for clarification are summarized below:
Capital Costs _197.1_$
Clarifier (two each) 20,000
$/Annual kkg ($/Annual ton) 0.14 (0.12)
Annual Costs $/year _^.
Clarifier (two each) 5,000
$/kkg ($/ton) 0.03 (0.03)
One available alternative to assure compliance to the
recommended 1983 limitations is to reduce the plant process
waste water flow value to about 200 1/kkg (48 gal/ton).
This can be achieved by numerous methods, such as by
converting to heat-exchange ncncontact metal cooling, by
further recycle with increased cooling capacity through
cooling ponds and towers, and by using the hot metal as an
evaporative source for the consumption of process waste
water. since specific incremental costs are not currently
159
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available for this flow value reduction (i.e., (1,340 1/kkg
(328 gal/ton) minus 200 1/kkg (48 gal/ton) multiplied by 415
kkg (458 tons) /day) , the costs of artificial evaporation are
used to approximate the maximum costs that this plant would
incur. Artificial evaporation is net herein recommended as
a control technique.
Capital Costs _ 1£U_!_
Incremental control 574,000
$/Annual kkg (S/Annual ton) 3.95 (3.58)
Annual Costs
Incremental control 283,000
$/kkg ($/ton) 1.95 (1.77)
Plant 118
This facility is a primary copper refinery geographically
located in an area of net evaporation and not located on-
site with a primary copper smelter. The recommended 1977
effluent limitations guideline for this plant is no
discharge of process waste water pollutants to navigable
waters. Currently, this plant discharges about 21,200 cu
m/day (5. 6 mgd) of fine casting cooling water on nearly a
once- through basis. One method tc achieve the proposed
limitation is to immediately reduce the contact water usage
of both the wire tar and the billet cooling systems to 2,100
1/kkg (500 gal/ton) , which is currently more representative
of the upper limit of the average flow usage range for this
source. Next, since these cooling operations are not
conducted on a full 24-hour basis, a holding pond, which
will also serve as a cooling pond, will be used to minimize
f lowproduction related variations. An assumed impurity -
related blowdown cf five percent, if one is even necessary,
from this holding/cooling pond will be discharged to an
evaporation pond with final process waste water disposal by
means of solar evaporation. The necessary acreage for this
evaporation pond calculates out to be 2.19 ha (5.4 acres) .
The associated costs for this "no discharge" method are as
follows:
Capital Costs J971 $
Reduction in water usage (no
operating costs) 41,000
Holding/cooling pond (lined) 36,000
Evaporation pond (lined) 177, .0.00
160
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Total 254,000
$/Annual kkg ($/Annual ton) 1.60 (1.45)
Annual Cpgts $/vear
Holding/cooling pond 9,000
Evaporating pond 44,000
Total 53,OQO~
$/kkg ($/ton) 0.33 (0.30)
Plant J19
This is a primary electrolytic copper refinery not located
on-site with a primary copper smelter. Current discharge
concentrations of process waste water pollutants and flow
usage indicate that this facility is in compliance to the
recommended 1977 effluent limitations. Recently, some
pollutant concentrations have been rather high, but this
seems to be a result of a local municipality's dumping of
wastes into this plant's pond.
Methods of additional recycle and reuse must be
incrementally applied to lower the flow value to assure
compliance to the 1983 proposed limitations. The current
flow value is 1,125 1/kkg (270 gal/ton); thus, a flow usage
reduction of 925 1/kkg (222 gal/ton) would be one method to
achieve the recommended limitations based upon BATEA. As
with P^ant 116, the costs of artificial evaporation will be
used to represent the maximum costs that this plant would
need for incremental control.
Capital Costs 1971 $
Incremental control 696,000
$/Annual kkg ($/Annual ton) 4.32 (3.91)
Annual Costs $/year
Incremental control 332,000
$/kkg ($/ton) 2.06 (1.87)
Plant. 121
This facility is located in the Northeast and is a primary
copper refinery not located on-site with a primary copper
smelter. Currently, the process waste water flow value at
this plant is about 710 1/kkg (170 gal/ton). One of the two
process waste water outfalls at this facility has been found
161
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-to have a higher concentration of copper than is considered
to be best practicable. Costs for a small lime and settle
treatment plant for this outfall are estimated below;
Ca£ital_Costs 1971 $__
Lime and settle treatment plant 60,000
$/Annual kkg ($/Annual ton) 0.53 (0.48)
Annual.Costs $/vear
Lime and settle treatment plant 60,000
$/kkg ($/ton) 0.53 (0.48)
This lime and settle treatment facility should be one
approach to achievement of the recommended 1977 effluent
limitations. Again, as with Plants 116 and 119, the costs
of artificial evaporation are used tc approximate the
maximum costs which this plant would have for incremental
control for compliance to the 1983 proposed limitations.
Capital_Costs 1971 $
Incremental control 311,000
$/Annual kkg ($/Annual ton) 2.76 (2.49)
Annual Costs $/year
Incremental control 190,000
$/kkg ($/ton) 1.68 (1.52)
Total Costs
Primary Copper Smelting Subcategorv. The total estimated
costs for Plants T03, 104, 105, 11o7~and 112, on the basis
of 1971 dollars, for achievement of the recommended 1977
effluent limitations guidelines, are $1,212,000 capital and
$284,000 annual. A summary of these costs is shown in Table
38.
Primary Copper Refining Subcategory. The total estimated
costs for Plants 116, 118, and 121,"on the basis of 1971
dollars, for achievement of the recommended 1977 effluent
limitations guidelines, are $334,000 capital and $118,000
annual. The costs for ccmpliance to the 1983
recommendations for Plants 116, 119, and 121, are estimated
to be $1,581,000 capital and $805,000 annual. Therefore,
the total estimated capital and annual costs to the plants
in this Subcategory are $1,915,000 and $923,000,
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TABLE 38. ADDITIONAL CONTROL AND TREATMENT COSTS (1971 $)
en
Plant
Designation
1977
Capital
Annual
1983
Capital
Annual
Total
Capital
Annual
PRIMARY COPPER SMELTING SUBCATEGORY
103
104
105
110
112
100, 101, 102 r\
106,107,108,4
109,111,113,)
114,1000 y
TOTAL
$ 410,000
51,000
7,000
410,000
334,000
0
$1,212,000
$ 86,000
10,000
2,000
103,000
83,000
0
$284,000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
$ 410,000
51,000
7,000
410,000
334,000
0
$1,212,000
$ 86,000
10,000
2,000
103,000
83,000
0
$284,000
PRIMARY COPPER REFINING SUBCATEGORY
116
118
119
121
115,117,120}
1005 )
$ 20,000
254,000
0
60,000
0
$ 5,000
53,000
0
60,000
0
$ 574,000
0
696,000
311,000
0
$283,000
0
332,000
190,000
0
$ 594,000
254,000
696,000
371,000
0
$288,000
53,000
332,000
250,000
0
TOTAL
$ 334,000
$118,000
$1,581,000 $805,000
$1,915,000 $923,000
-------
respectively. A summary of these costs is shown in Table
38.
Nonwater Quality Aspects
Energy Requirements
Specific data on energy requirements were not available from
most of the plants surveyed. The typically practiced
control techniques, as used by the facilities within these
two subcategories, are recycle and reuse of process waste
water, as well as disposal through sclar evaporation. These
techniques require a minimal amount of energy, since pumping
is the major mechanical requirement involved. Energy
consumption from lime treatment facilities is not
specifically known, but, as found in the associated industry
of primary zinc smelting, power requirements are generally
around 100 horsepower. Typically, especially where
electrolytic refining is practiced, nearly 99 percent of all
plant power needs will be consumed in metal production. The
remaining one percent is the energy value necessary for all
other plant needs, including water pollution control.
Therefore, this power consumption is considered negligible
in comparison to total plant needs.
Solid Waste Generation
When the process waste waters of the primary copper industry
are neutralized with lime, a sludge will be produced. The
volume of this sludge will primarily be dependent upon the
desired pH adjustment (i.e., the higher the value of pH, the
larger the volume of generated sludge).
One currently operating integrated primary copper smelter,
which also has an on-site electrolytic refinery, is
currently in the start-up phase of a new treatment facility.
The total effluent to this facility has been discussed in
Section VII and is comprised of acid plant blcwdown,
refinery wastes, floatation mill wastes, power plant wastes,
and plant sewage. Milk of lime, ferric chloride, and a
polyelectrolyte will be used to neutralize and settle 68,400
cu m/day (18 mgd) of plant process waste water. Waste
generation has been calculated to te about 36 kkg (40 tons)
per day, on a dry basis, and an area has been set aside for
the disposal of this sludge.
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Solid waste production by lime neutralization is considered
to have minimal iirpact, especially when considering the mass
of mill tailings and slag produced at many of these same
facilities.
165
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SECTION IX
BEST PRACTICABLE CCNTROL TECHNOLOGY CURRENTLY
AVAILABLE—EFFLUENT LIMITATIONS GUIDELINES
Introduction
The effluent limitations that must be achieved by July 1,
1977 are to specify the degree of effluent reduction
attainable through the application of the best practicable
control technology currently available. Such control
technology is based on the average of the best performance
by plants of various sizes and ages, as well as the unit
processes within the industrial category. This average is
not based upon a broad range of plants within the primary
copper industry, but upon the performance levels achieved by
the exemplary plants. Additional consideration was also
given to:
(1) The total cost of application of
technology in relation to the effluent
reduction benefits to be achieved
from such application.
(2) The size and age of the equipment and
plant facilities involved.
(3) The process employed.
(4) The engineering aspects of the
application of various types of
control techniques.
(5) Process changes.
(6) Nonwater quality environmental
impact (including energy requirements).
The best practical control technology currently available
emphasizes effluent treatment at the end of a manufacturing
process. It includes the control technology within the
process itself when the latter is considered to be normal
practice within the industry,
A further consideration is the degree of economic and
engineering reliability, which must be established for the
technology to be currently available. As a result of
demonstration projects, pilot plants, and general use, there
must exist a high degree of confidence in the engineering
and economic practicability of the technology at the time of
commencement of construction or installation of the control
or treatment facilities.
167
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Industry Category and Haste Hater Streams
One category of the industry encompassing the primary
smelting and refining of nonferrous metals (Standard
Industrial Classification Number 333) is the primary
smelting and refining of copper (SIC Number 3331). SIC
Number 3331 describes those establishments primarily engaged
in smelting copper from the ore, and in refining copper by
electrolytic or other processes. Operations such as the
mining and benefication of copper ore, as well as the
rolling, drawing, and extruding of copper, are classified
under other SIC's and are not a subject of this development
document. The secondary smelting and refining of nonferrous
metals, under SIC 3341, is also excluded from the proposed
requirements of this document.
For the purposes of establishing proposed effluent
limitations guidelines for the primary copper industry, two
subcategories have been defined, the primary copper smelting
subcategory and the primary copper refining subcategory.
The former subcategory includes all primary copper smelting
operations, and does not discern among those smelters which
are integrated with mining or milling operations or have
on-site electrolytic refining operations. The latter
subcategory, that for primary copper refining, includes all
primary copper refining operations which are not on the same
on-site location with a primary copper smelter. The
definition of these two subcategories evolved from both the
industry categorization discussion of Section IV and the
conclusions derived regarding raw waste (Section V) and
control and treatment technology (Section VII).
By the definition of a primary copper smelter, there are 15
currently operating primary copper smelting facilities in
the United States and these are the constituents of the
primary copper smelting subcategory. Also included in this
subcategory are four facilities which are either currently
under construction or are in startup. Three of these
facilities are planned replacements for three of the 15
currently operating smelters; one of the "under
construction" smelters will become the sixteenth smelter
after being "lined-out." A fifth primary copper facility
currently under construction will be a wet process operation
and, since there are no factual waste water data available
to describe its potential discharges to navigable waters, it
is not considered as part of the primary copper industry.
Many of the primary copper smelters are integrated with
mining and/or milling operations; whereas, only four are of
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the custom type (i.e., purchase all copper concentrates for
the primary smelting of copper). Four of the currently
operating smelters have on-site electrolytic refineries.
The proposed effluent limitations developed for this
subcategory are intended to control those process waste
waters, as clearly defined in this document, generated at
the primary copper sirelters and refineries, if such
operations are located on-site with the smelter.
By the definition, as established herein, of a primary
copper refinery, there are seven currently operating primary
copper refining facilities in the United States and these
are the constituents of the primary copper refining
subcategory. These seven operations are physically not
located on-site with a primary copper smelter. One primary
copper refinery is currently under construction, and
industry plans call for the closure of one currently
operating refinery upon start-up of the new facility. The
proposed effluent limitations developed for this subcategory
are intended to control those process waste waters, as
clearly defined in this document, generated at the primary
copper refineries not located on-site with a primary
smelter.
Waste_ Water Froir._thg Primary Copper
Smelting Subcategory
Effluent_LimitatiQns Eased_on the Application
oftthe Best Practicable Control Technology Currently Available
The recommended effluent limitation based on the application
of the best practicable control technology currently
available is no discharge of process waste water pollutants
to navigable waters.
The achievement of this limitation by use of control and
treatment technologies identified in this document leads to
the complete recycle, reuse, or consumption of all water
within the combined processes of the industry with an
associated result of no discharge of process waste water.
Since some primary smelters are located in geographical
areas of net precipitation and since several others are
located in areas of heavy rainfall event, the following
discharge provisions are proposed as part of the best
practicable effluent limitation:
A process waste water impoundment which is
designed, constructed and operated so as to contain
169
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the precipitaticn from the 10 year, 24 hour rainfall
event as established by the National Climatic Center,
National Oceanic and Atmospheric Administration, for the
area in which such impoundment is located may discharge
that volume of process waste water which is equivalent
to the volume of precipitation that falls within the
impoundment in excess of that attributable to the 10
year, 24 hour rainfall event, when such event occurs.
During any calendar month there may be discharged
from a process waste water impoundment either a volume
of process waste water equal to the difference between
the precipitation for that month that falls within the
impoundment and the evaporation within the impoundment
for that month, or, if greater, a volume of process
waste water equal to the difference between the mean
precipitation for that month that falls within the
impoundment anc the mean evaporation for that month
as established by the National Climatic Center,
National Oceanic and Atmospheric Administration, for the
area in which such impoundment is located (or as otherwise
determined if no monthly data have been established
by the National Climatic Center).
Any process waste water discharged pursuant to
the above paragraph shall conrply with each of the
following requirements:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units (mg/ll
TSS
As
CU
Pb
Cd
Se
Zn
pH Within the range 7.0 to 10.5
50
20
0.5
1.0
1.0
10
10
25
10
0.25
0.5
0.5
5
5
English units (ppm)
TSS 50 25
170
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As
Cu
Pb
cd
Se
Zn
20
0.5
1.0
1.0
10
10
Within the range
10
0-25
0.5
0.5
5
5
7.0 to 10.5
When commingled waters are contained in the impoundment area,
the volume of water allowably discharged to navigable waters
due to the conditions of the above paragraphs will equal the
volume calculated on the basis of the ratio of process waste
water volume and total impoundment volume.
Identification of the Best Practicable Control
Technology Currently Available
Slag Granulation. The best practicable control and treatment
technology currently available for waste water from slag
granulation is the elimination of water discharge by one of
the following approaches:
(1) Recycle or reuse of waste water from slag
granulation after treating the effluent, if
necessary, to reduce suspended solids by settling
and filtration.
(2) Air cool the slag by dumping to waste.
(3) Impoundment with disposal by solar evaporation.
To implement the recycle or reuse system for slag
granulation, the requirements are:
(a) A lagocn or pond to provide settling or cooling, or
a cooling tower with some settling capacity.
(b) A filter systerr, if necessary, with a capacity for
backwash.
Implementation of the slag dumping system would require a
slag dumping area and the equipment for transporting the
molten slag to this area.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagoon or pond with sufficient free surface area
to allow disposal through solar evaporation.
Acid Plant Slowdown. The best practicable control and
treatment technology currently available for waste water
from acid plant blowdown is the elimination of water
discharge by one of the following approaches:
171
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(1) Recycle or reuse of the waste water from acid plant
blowdown after treating, if necessary, to
neutralize and settle.
(2) Impoundment with disposal by solar evaporation.
To implement the recycle or reuse system for acid plant
blowdown, the requirements are:
(a) A neutralization facility with a clarifier, lagoon,
or pcnd to provide settling and cooling prior to
recycle or reuse.
(b) Possibly, more efficient primary particulate
control equipment to minimize entrained particulate
and, in turn, minimize the required blowdown
volumetric flow rate.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagoon or pond with sufficient free surface area
to allow disposal through sclar evaporation.
Contact Cooling Water. The best practicable control and
treatment technology currently available for waste water
from the contact cooling of blister copper, shot copper,
anode copper, fire-refined copper, and cathode-shape copper
is the elimination of the water discharge by one of the
following approaches:
(1) Recycle or reuse of waste water from molten metal
contact cooling after treating, if necessary, for
solids removal and cooling.
(2) Use of air cooling only for blister copper.
(3) Impoundment with disposal by solar evaporation.
To implement the recycle or reuse system for molten metal
contact cooling water, the requirements are:
(1) The addition to existing facilities of cooling
towers with some settling capacity, or a pond or
lagoon.
(2) Filtering system, with a capability for
backwashing.
(3) Provisions for sludge removal, dewatering, and
disposal.
Implementation of air cooling of blister copper would
require the use of castings of sufficient holding time for
cooling to eliminate any use of water as spray.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagcon or pond with sufficient free surface area
to allow disposal through solar evaporation.
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Wastes, For Refineries Operated On-Site with
Electrolyte. The best practicable control and
treatment technology currently available for waste water
from spent electrolyte is the elimination of this water
discharge by one of the following approaches:
(1) Reuse and recycle of spent electrolyte after copper
removal ty means of liberator cells, electrowinning
cells, and cementation, and recovery of nickel
values through evaporation, if nickel concentration
is sufficient.
(2) Sale of spent electrolyte for commercial value for
recovery of nickel sulfate, if nickel concentration
warrants, copper sulfate, and black acid.
(3) Impoundment with disposal by solar evaporation.
To implement the recycle or reuse system for spent
electrolyte, the requirements are:
(1) Liberator and electrowinning cells for copper
recovery. Additional cementation equipment for
maximum copper recovery.
(2) If nickel concentration is one of the reasons for
electrolyte purge, the recovery of nickel as nickel
sulfate, through evaporation.
(3) If any remaining solution can not be recycled as
electrolytic cell make-up, reuse for other purposes
may require neutralization and settling.
Implementation of the sale of electrolyte purge scheme would
require the availability of a market interested in one or
all of the possible recoverable constituents, copper,
nickel, and black acid.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagoon or pond with sufficient free surface area
to allow disposal through solar evaporation.
Electrolytic Refining Washing. The best practicable control
and treatment technology currently available for waste water
from electrolytic refining washing of cathodes, spent
anodes, and working areas is the elimination of this waste
water discharge by one of the following approaches:
(1) Recycle and reuse of this wash water by collecting
in a holding area, if necessary, and direct use as
electrolytic make-up water, or recycle as wash
water.
(2) Impoundment with disposal by solar evaporation.
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To implement -the recycle and reuse system for electrolytic
refinery washing water, the requirements are:
(1) A means of collection of such water (i.e., drainage
and collection systems).
(2) A sump or holding area for recycle or reuse.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagcon or pond with sufficient free surface area
to allow disposal through solar evaporation.
Slimes Recovery. The best practicable control and treatment
technology currently available for waste water from slimes
recovery is the elimination of this waste water discharge by
one of the following approaches:
(1) Ship slimes to other off-site locations for
recovery of contained elements.
(2) Impoundment with disposal by solar evaporation.
To implement the shipment or sale of slimes to another
facility, not operating on-site with the smelter-refinery
complex, would require the availability of a market for the
constituents of slimes.
Implementation of the impoundment system with solar
evaporation, in permissible geographical locations, would
require a lagoon or pond with sufficient free surface area
to allow disposal through solar evaporation.
Nickel Sulfate Vacuum Evaporators. The best practicable
control and treatment technology currently available for
waste water from barometric condenser entrainment carry-over
is the elimination of this waste water discharge by one of
the following approaches:
(1) The application of efficient mist eliminators and
proper operating and maintenance procedures to
minimize or eliminate entrainment.
(2) Sale of spent electrolyte to other facility for
nickel sulfate recovery.
(3) Conversion to open evaporators eliminating the need
for barometric condensers.
(4) Use of cooling towers.
(5) Impoundment with disposal by solar evaporation.
To implement the requirement of eliminating entrainment in
barometric condenser water would require the application of
deentrainment devices and good maintenance practices to
ensure proper operation.
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Implementation of a sale scheme for electrolyte purge or the
use of open evaporators would completely eliminate the
generation of process waste water from this source.
Solar evaporation is a least likely alternative, since, as
implemented, large volumes of water from the barometric
condensers would have to be contained. Becycle with a
cooling tower would be more applicable.
Miscellaneous Sources at Primary Copper Smelters .
DMA Plant Blow down and Purge. The best practicable control
and treatment technology currently available for waste
waters from DMA plant blowdcwn and purge is the elimination
of water discharge by one of the following approaches:
(1) Recycle or reuse of the waste water from acid plant
blowdown after treating, if necessary, to
neutralize and settle.
(2) Impoundment with disposal by solar evaporation.
Implementation of these technologies is as indicated for the
elimination of discharges from acid plant blowdown. DMA
purge volumetric flow rate can be minimized by the usage of
sulfurous acid in lieu of sulfuric acid.
Miscellaneous Sources. The best practicable control
and treatment technology currently available for other
miscellaneous sources, such as slurry overflow or
roaster-blending overflow, arsenic plant washdown, general
plant washdown, and byproduct scrubbing is the elimination
of water discharge by one of the following approaches:
(1) Recycle or reuse of all waste water after
neutralization, settling, and temperature control,
if necessary.
(2) Impoundment with disposal by solar evaporation.
Implementation of the above technologies for these small
miscellaneous volumes of process waste water are collection
facilities for recycle, neutralization and settling, if
necessary, or a pond of ample surface area for solar
evaporation.
storm Water. Runof f . The best practicable control and
treatment technology currently available for storm water
runoff which commingles with process waste waters is to
discharge that volume of water accountable to net
precipitation during each one month period. This technology
can be achieved by the following approaches:
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(1) Curb various areas of the plant to minimize storm
water runoff entrance into process waste water
effluents.
(2) Segregate the small impoundment areas containing
primary sirelter process waste water from the much
larger holding areas required for noncontact
cooling water, milling water, and ancillary
operation water; thus, reducing the total collected
volume of corrmingled stcrrr water.
(3) If seepage into impoundment areas is producing an
added volume of process waste water, the
impoundment area should be lined. Again,
segregation is very important on a cost basis.
Implementation of a discharge scheme for excess storm water
runoff would require an impoundment area of sufficient
freeboard to handle large volumes of storm water runoff.
Instrumentation necessary to validate excess rainfall, in
inches, would also be required.
Rationale for Selecting the Best Practicable Control
Technology Currently Available
Slag Granulation. Of the 15 currently operating primary
copper smelters, 11 perform slag dumping, while the four
remaining smelters practice slag granulation. Of these
four, one smelter reuses all of its slag granulation water
in its copper concentrators as part of the floatation media,
one collects all of its slag granulation water in its mill
tailings pond and recycles and reuses all of this water for
slag granulation and on-site irrigation, and the third
recirculates nearly all of its granulation water from its
granulation water clarification pond. The remainder of this
water overflows into five miles of tailings pond with a
resultant discharge. "New smelter" plans at this third
facility call for slag dumping when the new smelter becomes
operational and replaces most of the existing operation.
The fourth smelter currently employing slag granulation
operates on a once-through basis with a resultant discharge
to navigable waters. Two other primary smelters which are
currently under construction will both use slag dumping.
Thus, of the 18 primary copper smelting operations discussed
above, two are currently discharging and the other 16 are
operating, or plan to operate, at no discharge of process
waste water pollutants.
Acid Plant_Blowdqwn. Of the 11 currently operating primary
copper smelters that operate metallurgical sulfuric acid
plants on smelter offgases, seven are currently operating at
no discharge of process waste water pollutants from acid
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plant blowdown by virtue of recycle, reuse, and solar
evaporation. Methods of reuse include using the effluent as
a gas preconditioner prior to the hot gas electrostatic
precipitators, using as a leaching medium/ and using as part
of the mill concentrator feed. Recycle is prevalent at
other plants. Two of the 11 plants are currently attempting
no discharge by application as a gas preconditioner and as a
blending agent for roaster feed. The remaining two smelters
have discharges from this source but only after treatment by
liming and settling. Two new metallurgical acid plants at
new smelters will both operate at no discharge by virtue of
solar evaporation at one and reuse from a thickener overflow
at the other. Thus, of the 13 described metallurgical acid
plant blowdowns, 11 are, or will shortly be, at no discharge
of process waste water pollutants.
Contact Cooling Water. Of the 22 contact cooling operations
at the 15 currently operating primary copper smelters
(including four smelters with on-site refineries), 14 are
currently operating at nc discharge of process waste water
pollutants, two anticipate no discharge, two discharge
intermittently, and four discharge continuously. These 22
contact cooling operations include three blister copper cake
cooling facilities, all at no discharge; two copper shot
cooling operations, both discharging; two fire-refined
copper (cathode-shape) cooling operations, with one
intermittently discharging; nine of 11 anode casting
operations at, or very near, no discharge, with one
operating on essentially a once through basis and the other
almost at complete recycle; and four cathode-shape casting
operations, with three at, or very near, no discharge of
process waste water pollutants. Plans at some of the new
smelters include closed circuit cooling water by means of e.
cooling tower with the blowdown to an evaporation pond and
retainment of existirg "no discharge" cooling facilities.
Refinery Wastes, For Refineries Operated On-Site With
A Primary Copper Smelter.
S£>ent Electrolyte. Of the four smelters which operate
on-site electrolytic refineries, none are currently known to
discharge any process waste water from this source.
Recovery of NiSO4, CuSO^, and black acid, solar evaporation
of spent electrolyte, and reuse in electrolytic cells are
all common practices.
Electrolytic Refinery. Washing* There are no known
discharges of process waste waters from this source at the
four on-site refineries. Reuse of this water as
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electrolytic make-up and as a make-up ingredient in a copper
sulfate plant are both commonly practiced.
Slimes Recovery. Only one primary refinery operating
on-site with a primary smelter recovers precious metals from
slimes. This plant currently operates at no discharge of
process waste water frcm this source by means of an
evaporaton pond. Scrubbers on Dore furnaces are also at no
discharge.
NiSO4 Vacuum Evaporators. None of the four on-site
electrolytic refineries are known to be currently operating
barometric condensers.
Miscellaneous Sources.
DMA Plant Slowdown and Purge. Three of the 15 currently
operating primary copper smelters employ DMA systems. One
plant is attempting to use all of its blowdown, along with
acid plant blowdcwn, as a blending medium for roaster feed,
one plant uses all of its blowdown in its mill concentrator
circuit, and the third plans pH adjustment of its blowdown
with ammonia and subsequent use as a gas preconditioner
prior to primary particulate control. Of the three purge
streams generated by the three DMA systems, one reuses it in
its mill concentrator circuit, one will attempt to use all
of its purge by preconditioning a hot gas stream prior to an
electrostatic precipitator, and the third discharges after
treatment with activated carbon.
Other Miscellaneous Sources. One discharge has been
reported from a wetting of roaster feed operation. This is
due primarily to the srrelter operator's attempts to use all
of his acid plant and DMA plant blowdown as the blending
media, but this has not been achieved to date. One
currently operating smelter has an arsenic plant. This
smelter plans to use the washdcwn water from this plant to
precondition the roaster and reverberatory furnace gases
prior to the hot electrostatic precipitator. General plant
washdown water is usually collected and recycled or reused
as electrolytic make-up. All krcwn byproduct scrubber
applications are currently in closed-circuit operation.
Storm Water Runoff... At some primary copper smelters,
provisions are made to collect runoff for process
application. At other smelters, runoff adds to the process
waste water burden by commingling with smelter process waste
waters. By providing discharge provisions for this excess
water source, the vast majority of problems associated with
its presence should be alleviated.
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Technology Costs. On the basis of the information contained
in Section VIII, it is concluded that those primary copper
smelters not presently achieving the recommended effluent
limitations guidelines would require an estimated capital
investment of $1,212,000 and an increase in annual operating
costs of about $284,000 to achieve the recommended
limitations.
Waste Hater From the Primary Copper
Refining SubcateqQry
Effluent Limitations Based on the_Application of the. Best
Practicable Control Technology Currently Available ~"
Primary Copper Refineries Geographically Located in Areas
of Net Evaporation, The recommended effluent limitation
based on the application of the best practicable control
technology currently available is no discharge of process
waste water pollutants to navigable waters.
The achievement of this limitation by use of control and
-treatment technologies identified in this document leads to
the complete recycle, reuse, or consumption of all water
within the combined processes of the industry with an
associated result of no discharge of water.
Since some primary copper refineries are geographically
located in areas of heavy rainfall event, the following
discharge provisions are proposed as part of the BPCTCA
effluent limitations:
A process waste water impoundment which is designed,
constructed and operated so as to contain the
precipitation from the 10 year, 24 hour rainfall event
as established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located may discharge that
volume of process waste water which is equivalent to the
volume of precipitation that falls within the
impoundment in excess of that attributable to the 10
year, 24 hour rainfall event, when such event occurs.
During any calendar month, there may be discharged from
a process waste water impoundment either a volume of
process waste water equal to the difference between the
precipitation for that month that falls within the
impoundment and the evaporation within the impoundment
tor that month, or, if greater, a volume of process
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waste water equal to the difference between the mean
precipitation for that month that falls within the
impoundment and the mean evaporation for that month as
established by the National Climatic Center, National
Oceanic and Atmospheric Administration, for the area in
which such impoundment is located (or as otherwise
determined if no monthly data have been established by
the National Climatic Center).
Any process waste water discharged pursuant to the above
paragraph shall comply with each of the following
requirements:
Effluent limitations
Effluent
characteristic
Maximum for
any 1 day
Average of daily
values for 30
consecutive days
shall not exceed
Metric units (mg/11
TSS
As
cu
Se
Zn
Oil and grease
pH
50
20
0.5
10
10
20
Within the range 7 to
25
10
0.
5
5
10
10.5
25
English units (ppm)
Oil and grease
50
20
0.5
10
10
20
Within the range 7 to
25
10
0.25
5
5
10
10.5
When commingled waters are contained in the impoundment
area, the volume of water allowably discharged to
navigable waters due to the conditions of the above
paragraphs will equal the volume calculated on the basis
of the ratio of process waste water volume and total
impoundment volume.
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Primary.Copper Kefineries Geographically Located in Areas of
Net^Rainfall. The recommended effluent limitations based on
the application of the best practicable control technology
currently available for primary copper refineries
geographically located in areas cf net rainfall are:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units (kilograms per 1,000 kg
of_ product)
TSS
As
Zn
Se
Cu
Oil and grease
pH Within the range 7.0 to 10.0
0.10
0.04
0.02
0.02
0.001
0.04
0.05
0.02
0.01
0.01
0.0005
0.02
English units (pounds per 1,000 lb
of product)
Oil ana grease
0.10 0.05
0.04 0.02
0.02 0.01
0.02 0.01
0.001 0.0005
0.04 0.02
Within the_range 7.0 to 10>0
Identification of the Best Practicable Control Technology
Currently Available
Primary Copper Refineries. Geographically Located iin Areasr.of
Net ..Evaporation. The process waste waters attributed to the
primary refining of copper at one currently operating
facility are retained with recycle and are also retained in
a lined pond for disposal through solar evaporation. By
providing a storm water monthly discharge-balance provision
for the refineries in net evaporation areas, a no discharge
of process waste water pollutants limitation should be
readily maintained.
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Primary Copper Refineries Geographically Located .in Areas of
Net .Rainfall. Disposal sources, specifically through reuse
of process waste waters at on-site mining, milling, and
smelting operations, are not available for primary copper
refineries not located on-site with primary copper smelters.
Thus, the best practicable control technology currently
available for the five remaining primary refineries is to
reduce process waste water volumetric flow rates, through
recycle and reuse, to levels demonstrated by the average of
the best of these same facilities. Subsequent liming and
settling cf the resulting effluent, with concentration
values for significant pollutants (as considered to be best
practicable) , results in effluent loadings based upon
refined copper production.
Contact Cooling Water. As discussed in Section VII, most of
the refinery operations recirculate contact cooling water
from cooling ponds and discharge a bleed. The amount of
bleed is determined by the capacity of the pond and its
settling and cooling ability.
S£§nt Electrolyte. Ncne of the five primary refineries are
known to discharge spent electrclyte. Byproduct production
of NiSO4, CuSO4, black acid, and the return of spent
electrolyte to the electrolytic operation is common
practice.
Slimes Recovery. Three of the five refineries ship their
slimes elsewhere for precious metal recovery. Currently,
the two, which do recover slimes content, discharge the
small flow volumes, but only after neutralization.
Electrolytic Refinery Washing. Reuse of spent anode,
cathode and hose-down wash water is generally practiced with
complete containment as either electrolytic make-up or
make-up for copper sulfate byproduct production.
NJSO4 Vacuum Evaporators. One of the five primary
refineries is known to operate barometric condensers on
NiSO4 vacuum evaporators. Entrainment of process waste
water pollutants can be minimized or eliminated by the
application of efficient mist eliminators and proper
operating and maintenance procedures. Conversion to open
evaporators or the use of cooling towers also represent best
practicable control technology for this large source of
process waste water.
Process Waste Water Volumetric Flow Rates . One parameter
used for establishing effluent limitations is the average of
the best process waste water volumetric flow rates. RAPP
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data and company data, collected during this study, were
analyzed to determine the value cf the best practicable flow
volume. Noncontact water and water from ancillary
operations were not considered. The data revealed the
following tabulation:
Prod (kkgj. flowjlgdl 1/kkg
115 508 1.09x10* 2160
116* 415 0.83x10* 2000
119 459 0.55x10* 1200
__ 121 __ 263 1.27x10* 4800
*Does not consider barometric condenser water.
The average of the best flow values is about 2000 1/kkg (480
gal/ton) cf copper.
Process __ Waste Water Treated __ Concentration Values. Based
upon analyses of data contained in section VII of this
development document, liming and settling of process waste
water is considered to be the best practicable treatment
approach. The following concentrations of pollutant
characteristics are considered to be test practicable values
after the liming and settling treatment:
Pollutant Pollutant
Characteristic Concentration (mg/1)
1SS ~ 25
As 10
Zn 5
Se 5
Cu 0.25
Fe 0.25
Ni 0.25
Cd 0.50
Pb 0.50
Oil and grease 10
pH within the range 7.0 to 10.0
By controlling the concentrations of zinc and copper,
concentration values of iron, nickel, cadmium and lead will
be minimized by coprecipitation. These concentrations were
obtained after an analysis of the various concentrations
shown in Tables 35, 36, and 37 and the theoretical
presentations shown in Figures 11, 12, and 13.
Resultant Best Practicable ^Effluent __ Limitations. The
proposed effluent limitations were derived as the product of
the best practicable flow value (1/kkg) and the best
practicable pollutant characteristic concentrations (mg/1) .
These calculated products are considered to be average
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discharge values and are tabulated as "average of daily
values for 30 consecutive days shall not exceed." As
demonstrated by ether industries, the one day maximum best
practicable effluent limitations should not exceed the
"average 30-day daily value" by more than a factor of two.
Technology Costs. On the basis of information contained in
Section VIII, it is concluded that those primary copper
refineries not presently achieving the recommended 1977
effluent limitations would require an estimated capital
investment of $334,000 and an increase in annual operating
costs of about $118,000 to achieve the recommended
limitations.
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SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE —
EFFLUENT LIMITATIONS GUIDELINES
Waste Water From the Primary Copper
Smelt. ing_Subcate<
The best available technology economically achievable for
the primary copper smelting subcategory is identical to the
best practicable control technology currently available.
The corresponding effluent limitation is no discharge of
process waste water pollutants to navigable waters. Storm
water runoff discharge provisions for this subcategory are
identical to those proposed in Section IX for the primary
copper smelting subcategory.
Waste Hater From the Primary Copper
RefininaSubcategorv
^»^» W* ^V**^v^^.^£i^h» ^•-•V^K^B -^ ^^ ^—^* ^ff^f ^*
Effluent Limitations Based on the.Application of the Best
Available Technology Economically Achievable
Primary Copper Refineries Geographically Located_in_Areas^ of
Net.Evaporation. The best available technology economically
achievable for those refineries, not operated on-site with a
primary smelter and located in geographical areas of net
evaporation, is identical to the best practicable control
technology currently available. The corresponding effluent
limitation is no discharge of process waste water pollutants
to navigable waters. Storm water runoff discharge
provisions are identical to those proposed in Section IX for
this part of the primary copper refining subcategory.
Primary^Copper Refineries Geographically Located in_Areas of
Net Rainfall. The recommendedeffluent" limitations based
upon the application of the best available technology
economically achievable for primary copper refineries
geographically located in areas of net rainfall are:
Effluent limitations
Effluent Average of daily
characteristic Maximum for values for 30
any 1 day consecutive days
shall not exceed
Metric units (kilograms per 1,000 kg
of product)
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TSS 0,01 0.005
As 0.004 0.002
Zn 0.002 0.001
Se 0.002 0.001
Cu 0.0001 0.00005
Oil and grease 0.004 0.002
pH Within the range 7.0 to 10.0
English units (pounds per 1,000 Ifc
of product)
TSS 0.01 0.005
As 0.004 0.002
Zn 0.002 0.001
Se 0.002 0.001
Cu 0.0001 0.00005
Oil and grease 0.004 0.002
£HKithin_the range .7.0 to 10.T0.
Identification of the_Best Available Technology
Economically Achievable
Primary Copper Refineries Geographically Located in Areas_of
Net Rainfall. The best available technology economically
achievable for the primary copper refineries, as defined, is
a continued reduction cf process waste water volumetric flow
rate by further recycle and reuse of process waste water and
the treatment of the resultant volume by lime and settle
prior to discharge.
Ratipnale for Selecting the Best Available
Technology Economically Achievable
Primary Copper Refineries Geographically Located
in Areas of Net^Rainfall.
Contact Cooling Water. Through the use of well-designed
cooling towers or ponds, and possibly the application of
side-stream filtration, the bleed from contact cooling for
maintenance of acceptable salt concentrations should be very
small in volume. Additional bleed volume could be reduced
by using the heat evolved in cooling one metric ton of
molten copper (either anode or cathode) as evaporative
energy. It has been calculated that nearly 300 1 (79 gal)
of water can be evaporated by this heat source. A bleed of
186
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about 100 1/kkg (24 gal/ton) is considered best available
from this source.
Spent Electrolyte^ Electrolytic Refinery Washing,, and NJSO4
Vacuum £vagorators_» Best practicable values from these
sources are already low in value, and anticipated
consumptive volumes per ton of product are expected to be
about 40 1/kkg (10 gal/ton), as best available, from these
same sources.
Slimes Recovery. Anticipated flow values for this source
are expected to be about 60 1/kkg (14 gal/ton).
Total. A total of 200 1/kkg (48 gal/ton), a 90 percent
reduction from best practicable, is used as a basis for the
calculation of the best available effluent limitations.
Process Waste Water Treatment concentration Values. The
identical concentration values for each of the pollutant
characteristics discussed in Section IX are used as a basis
for the calculation of the test available effluent
limitations. Additional or alternate forms of treatment are
not considered available for compliance to the best
available effluent limitations. Such forms are sulfide
precipitation and conversion to a solid, both of which have
been discussed in Section VII.
Resultant Best Available Effluent Limitations.. The proposed
effluent limitations were derived as the product of the best
available flow value (1/kkg) and the best available
pollutant characteristic concentrations (mg/1). These
calculated products are considered to be average discharge
values and are tabulated as "average of daily values for 30
consecutive days shall not exceed." As demonstrated by other
industries, the one day maximum best available effluent
limitations should not exceed the "average 30 day daily
value" by more than a factor of two.
Technology Costs. Incremental capital and annual operating
costs for the three primary copper refineries of this
subcategory, which would need incremental control and
treatment practices to comply to the recommended 1983
effluent limitations, are approximately $1,581,000 and
$805,000, respectively.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
The best available demonstrated control technology,
processes, operating methods, cr other alternatives are
identical to the best available technology economically
achievable. The corresponding standard of performance is
identical to the effluent limitations guidelines established
from usage of the best available technology economically
achievable.
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SECTION XII
ACKNOWLEDGMENTS
This document was developed by the Environmental Protection
Agency. The original contractor's draft report, dated
December, 1973 was prepared by Battelle Memorial Institute,
Columbus, Ohio, under contract no. 68-01-1518. Mr. Robert
Ewing, under the direction of Mr. John B. Hallowell,
prepared this original (contractor«s) draft report.
This study was conducted under the supervision and guidance
of Mr. George S. Thompson, Jr., Project officer.
Preparation, organizing, editing, and final rewriting of
this report was accomplished by Mr. Thompson.
The following members of the EPA working group/steering
committee provided detailed review, advice and assistance:
W.J. Hunt, Chairman
G.S. Thompson, Jr.,
Project Officer
S. Davis
D. Fink
J. Ciancia
T. Powers
Effluent Guidelines Division
Effluent Guidelines Division
Office of Planning and Evaluation
Office of Planning and Evaluation
National Environmental Research
Center, Edison
National Field Investigation Center,
Cincinnati
Excellent guidance and assistance was provided to the
Project Officer by his associates in the Effluent Guidelines
Division, particularly Messrs. Allen Cywin, Director,
Effluent Guidelines Division, Ernst P. Hall, Deputy
Director, and Walter J. Hunt, Branch Chief.
The cooperation of individual primary copper companies, who
offered their plants for survey and contributed pertinent
data, is greatly appreciated. These include:
American Smelting and Refining Company
Kennecott Copper company
Anaconda company
Cities Service Company
Copper Range Company
Inspiration Consolidated Copper company
Magma Copper Company
Phelps-Dodge Corporation
The cooperation of the Water Pollution Control Subcommittee
of the American Mining Congress is also appreciated.
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Acknowledgment and appreciation is also given to Ms. Kay
Starr, Ms. Nancy Zrubek, and Ms. Brenda Holmone of the
Effluent Guidelines Division secretarial staff.
19;
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SECTION XIII
REFERENCES
1. Metal Statistics^ 1973, American Metal Market, Fairchild
Publications7 Inc., New York, N." Y, (1973).
2. Beall, J. V., "Copper in the U. S. — A Position
Survey", Mining Engineering, p 35-47 (April, 1973}.
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(June, 1967).
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Circular 8225 (1965).
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Industrial Russian Roulette", Engr. Mining J., p 61-71
(July, 1971) .
8. Lutjen, G., Treilhard, D. G., Price, F. C., "Facing the
Change in Copper Technology", Chemical Engineering and
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10. Lansche, A. M., "Selenium and Tellurium - A Materials
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13. Dalbke, R. G., and Turk, A. J., "Water Polluticn Control
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Metallverarbeitenden Industrie, Ausfallung der
Schwermetalle", Bander Blecher Rohre 6, a (1965).
17. stumm, W., and Morgan, J. J., Aguatic chemistry, Wiley-
Interscience, New York (1970).' ~"
18. Jenkins, S. N., Knight, D. G., and Humphreys, R. E.,
"The Solubility of Heavy Metal Hydroxides in Water,
Sewage, and Sewage Sludge, I. The Solubility of Some
Metal Hydroxides", Int. Jour. Air 6 Water Pollution, 8,
537-556 (1964).
19. Maruyama, T., Hannah, S. A., and Cohen* J. M., "Removal
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Control Federation Meeting (1972).
20. Kantawala, D. , and Tomlinson, H. B., "Comparative Study
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21. Dean, J. D., Bosqui, F. L., and Lanowette, K. H.,
"Removing Heavy Metals from Waste Water", Env. Sci.
Technology, 6, 518-522 (1971).
22. Solubilities of..Inorganic and Metalorganic Compounds,
(Seidell) Linke, W. F., (Ed,) 4th Ed. American Chemical
Society, Washington, D. C. (1958) .
23. Curry, N., "Philosophy and Methodology of Metallic
Waste Treatment", presented at the 27th Annual
Industrial Waste Conference, Purdue University (1972).
24. Johnson, D.E.L., "Reverse Osmosis Recycling System for
Government Arsenal", Amer. Metal Market (July 31, 1973),
25. Linstedt, K. D., Houck, C. P., and O'Connor, J. T.,
"Trace Element Removals in Advanced Waste Water
194
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Treatment Processes", Water Polln. Control Fed. J. 48,
(7) , 150-13 (1971) .
26. Eckenfelder, W. W., Jr., Water Quality Engineering for
Practicing Engineers^ Barnes and Noble, Inc., New York
(1970) .
27. Patterson, J. W., and Minear, R. A., "Waste Water
Treatment Technology", Report to the Illinois Institute
for Environmental Quality, Chicago, Illinois (August
1971).
28. Kolthoff, I. M., and Sandell, E. B., Textbook of
Quantitative Inorganic Analysis, 3rd ed., The Macmillan
Co., New York "(1952) 7~
29. Bauman, H. C., "Up-to-Date Equipment Costs", Inst. Eng.
Chem., 54(1), 49 (1962).
30. Peters, M. S., and Timmenhaus, K. D., Plant Design and
Economics for Chemical Engineer$, 2nd Edition, McGraw
Hill Book Co., New York (1968)."
31. Mendel, O., "Cost Comparisons for Process Piping", Chem.
Eng., pp 255 (June 17, 1968).
32. Jacobs, H. L., "In Waste Treatment—Know Your Chemicals,
Save Money", Chem. Eng., pp 87 (May 30, 1960).
33. Perry, J. H., ed., Cheirical Engineers Handbook 3rd
Edition, McGraw-Hill Book Co77 New York "(1950) . r
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Anonymous, "Emis sions Controversy Enters Pha s e II",
Engineering and Mining Journal, 172, (12), 78-81
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First Off the Mark", Engineering and Mining Journal,
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5. Battelle's Columbus Laboratories, "Final Report on Water
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Process: from Pilot Study to Full-scale Plant",
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7. Dayton, S., "Wet Scrubbing of Weak SO2 Gets Trial at New
McGill Pilot Plant", Engineering and Mining Journal,
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Atlas Publishing Conine., New~York (1968), pp 68-91.
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Mining Engineering, 24, (8), 58-60 (August, 1972).
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Wastes and Low-grade Ores", Engineering and Mining
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Metallurgy", Mineral Industries Bulletin^ IIX (4), 1-18
(July, 1968).
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Engineering and Mining Journal, 174, (4), RR-HHH (April,
1973).
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Improved Copper Leaching at Butte", Mining Engineering,
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197
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(1973) .
198
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SECTION XIV
GLOSSARY
Acidity
Capacity of waste water for neutralizing a base. It is
normally associated with the presence of carbon dioxide,
mineral and organic acids and salts of strong acids or weak
bases. An acidic solution has a pH of Jess than 7.
Act
The Federal Water Pollution Control Act Amendments of 1972,
Alkalinity
A term representing the presence of salts of weak acids.
The hydroxides, carbonates, and bicarbonates of calcium,
sodium, and magnesiuir are the common impurities that cause
alkalinity. An alkaline solution has a pH greater than 7.
Ancillary Operations
Operations which are often carried out at primary copper
plants but are not an essential part of the processing, for
example, rod, wire, cr rolling operations, or power
generation.
Anode
The positive terminal of an electrolytic cell. In
electrolytic refining, the impure copper anode is dissolved
to provide pure copper at the cathode. In electrowinning,
the anode is composed of insoluble antimonial lead, and the
copper supplied to the cathode comes from the electrolytic
solution.
Baghouse
Large chamber for holding bags used in the filtration of
gases from a furnace, for the recovery of metal oxides,
dust, and similar solids suspended in the gases.
199
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Barometric Condenser
An apparatus used to condense vapor, in which the vapors are
condensed by direct contact with water in a vessel set
sufficiently high so that the water drains from it through a
barometric leg into a sealed tank or hot well.
Bar or Wire Bar
Refinery shape for rolling intc red and subsequent drawing
into wire. Approximately 22.5 to 32 sq cm (3.5 to 5 sq in.)
in cross section and from 100 to 140 cm (38 to 54 in.) in
length, with a weight of 60 to 190 kg (135 to 420 Ib).
Best Available Technology Economically Achievable
Level of technology applicable to effluent limitations to be
achieved by July 1, 1983, for industrial discharges to
navigable waters as defined by Section 301 (b) (2) (A) of the
Act.
Best Practicable Control Technology Currently Available
Level of technology applicable to effluent limitations to be
achieved by July 1, 1977, for industrial discharges to
navigable waters as defined by Section 301 (b) (1) (A) of the
Act.
Billet
Refinery shape primarily for tube manufacture. Billets are
generally circular in cross section, 7.6 to 25 cm (3 to 10
in.) in diameter and up to 132 cm (52 in.) long, with a
weight of 45 to 680 kg (100 to 1500 Ib).
Blister Copper
The still-impure copper cast into pigs after the converting
process. The name derives from the rough upper surface the
pigs exhibit upon solidification, resulting from the
expulsion of gases during solidification.
200
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Biochemical Oxygen Demand (BOD^
A measure of the oxygen demand in sewage and industrial
wastes or in the streair, determined by chemical techniques,
One technique (BODJ5) determines the 5-day oxygen demand.
Slowdown
A discharge from a system, designed to prevent a buildup of
seme material, as in a boiler to control dissolved solids.
Cake
Refinery shape, rectangular in cross section, for rolling
into plate or sheet, with a weight of 60 to 1815 kg (140 to
4000 Ib).
Calcine
The oxidized or partly oxidized product of roasting.
Capital Costs
Financial charges which are computed as the cost of capital
times the capital expenditures for pollution control. The
cost of capital is based upon a weighted average of the
separate costs of debt and equity.
Category and Subcateggry
Divisions of a particular industry which possess different
traits affecting waste treatability and requiring different
•»+• 1 -i mi 4- a-^- -i /"»ne
effluent limitations.
Cathode
The negative terminal of an electrolytic cell. In electro^
lytic refining and electrowinning of copper it is a 99.95
percent copper plate, customarily 1.25 to 2.25 cm (1/2 to
7/8 in.) thick and 0.28 sq m (3 sq ft), upon which the
copper from the electrolytic solution is deposited.
201
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Cementation
Process of obtaining copper frcm a copper sulfate solution
by precipitation with scrap iron, such as the iron in
detinned tin cans. The pregnant solution derived from
leaching flows over the scrap where the less noble metal
(iron) replaces the copper in solution.
Cement Copper
The product of cerrentation.
Clarification
Process of removing turbidity and suspended solids by
settling. Chemicals can be added to improve and speed up
the settling process through coagulation.
Chemical Oxygen Demand (CQD^
A measure of the oxygen demand equivalent of that portion of
matter in a sample which is susceptible to oxidation by a
strong chemical oxidant.
Concentrating
Upgrading of the copper content in copper ore by partial
removal of waste material. The ere is crushed, ground in
mills, sent through a series of flotation cells, and then
passed through thickeners and filters. Final copper-r
concentrate output is sent to the sirelter.
Converting
Blowing of air through molten matte in a furnace (converter)
to further purify the sirelter product before it is fire
refined or electrolytically refined. Initially in convert-
ing, the iron sulfide of the matte is oxidized to iron oxide
and sulfur dioxide, then additional air blowing oxidizes the
copper sulfide t.o sulfur dioxide and copper. This copper,
if cast into pigs before refining, is called blister copper.
202
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Custom Smelter
A smelter processing copper concentrates purchased from
other sources. these different concentrates are
specifically blended to produce a specific quality "custom"
product.
Depreciation
Accounting charges reflecting the deterioration of a capital
asset over its useful life.
Pore Metal
Metal consisting of gold and silver.
Dust collector
An air pollution control device for removing dust from air
streams. Filtration, electrostatic precipitation, or
cyclonic principles may be utilized, but the term usually
infers a dry system, not involving a water stream.
Effluent
The waste water discharged from a point source to navigable
waters.
Effluent Limitation
A maximum amount per unit of production of each specific
constituent of the effluent that is subject to limitation in
the discharge froir a point source.
Effluent ^Leading
The quantity or concentration of specified materials in the
water stream from a unit or plant.
Electrolytic Refining
The separation of copper from other metals and impurities by
electrolytic oxidation at the anode and the deposition of
203
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copper as pure metal by electrolytic reduction at the
cathode, using as an electrolytic solution copper sulfate
and sulfuric acid. When current is applied, copper is
dissolved from the iirpure ccpper anode (the product of
converting or fire-refining) and enters the electrolyte as
copper sulfate (electrolytic oxidation); at the same time,
an equivalent amount of copper plates out on the cathode
(electrolytic reduction). After electrolytic refining, the
cathodes are melted in furnaces where the physical
properties of the copper are adjusted to specifications
before casting into refinery shapes.
Electrostatic Precipitatcr
A gas cleaning device using the principle of placing an
electrical charge on a particle, which is then attracted to
oppositely charged plates or wires. The device uses a d-c
potential approaching 40,000 volts to ionize and collect the
particulate matter. The collector plates are intermittently
rapped to discharge the collected dust into a hopper below.
The system may operate dry or the plates may be continuously
cleaned by a falling film of water.
Electrowinning
The recovery of ccpper from a leach solution by
electrolysis. The anode is an insoluble material such as
antimonial lead, the cathode is a thin 1.25 to 2.25 cm (1/2
to 7/8 in.) copper sheet, and the electrolyte solution is
derived from solvent extraction or vat leaching. Cathodes
from electrowinning are melted and cast into conventional
refinery shapes.
Fire-Refining
A high temperature furnacing process employing oxidation,
fluxing, and reduction by which blister copper is further
purified to produce either a final product, fire-refined
copper, or anodes for subsequent electrolytic refining. Air
introduced into the melted blister copper produces copper
oxide. Sulfur, zinc, tin, and iron are also oxidized and
can be removed by skimming. By using basic fluxes, lead,
arsenic, and antimony can be removed. Reduction of the
oxidized copper at the completion of the process is accom-
plished by poling.
204
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Flocculation
The formation of a very fine, fluffy mass formed by the
aggregation of fine suspended particles in a liguid.
Flotation
The separation, during concentration, of different mineral
particles from each other by agitating the finely ground ore
in water using air bubbles. Reagents added to the ore
attach themselves -to the sulfide minerals which then adhere
ro the air bubbles and rise tc the surface where they are
removed in the froth.
32S
Gallons per minute.
Gangue
The worthless rock or other material from which valuable
metals or minerals have been extracted.
Hood
A covering over the converter for exhausting the fumes,
dusts, and gases produced during the converting process.
Industrial Waste
All wastes streams within a plant. Included are contact and
noncontact waters. Not included are wastes , typically
considered to be sanitary wastes.
Refinery shape for storage or transportation and later to be
remelted for alloy production. Usually notched to
facilitate breaking into smaller pieces. Weight of 9 to 16
kg (20 to 35 Ib).
205
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Integra-bed Smelter
A smelter processing copper concentrates, most of which have
been produced on-site at a milling operation. On-site mines
and electrolytic refineries may also be present.
Investment Costs
The capital expenditures required tc bring the treatment or
control technology into operation. These include the
traditional expenditures such as design; purchase of land
and materials; site preparation; construction and instal-
lation; etc*; plus any additional expenses required to bring
the technology into operation, including expenditures to
establish related necessary solid waste disposal.
Launder
A rectangular tank or channel in which scrap iron is placed
during the cementation process. The pregnant leach solution
containing copper sulfate flows over the iron, deposits its
copper, and is circulated back to the leach area as a barren
solution.
Leaching
The separation of copper from the gangue or low-grade ore by
means of dissolving the metal in some solvent (usually
sulfuric acid in 5 to 10 percent solution) and then
recovering it from the solution in a relatively pure form.
Leaching is usually applied to oxidized or mixed oxidized
and sulfide ores. Four principal methods of leaching are
used in the treatment of copper ore: (1) leaching in place
or in situ leaching; (2) heap or dump leaching; (3) vat or
percolation leaching; and (4) leaching by agitation.
Liberator Cell
Electrolytic cell having an insoluble anode, and a copper
cathode, and using as electrolyte the copper-containing
solution bled off from the electrolytic refinery when that
solution contains too large a buildup of soluble impurities.
Copper from the solution and a copper arsenic sludge are
recovered at successive cathodes, while soluble salts, such
as nickel sulfate, are recovered in subsequent evaporation.
206
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Liquid Ion Exchange, LIX
Solvent extraction.
Liter
1000 cubic centimeters.
Matte
A crude mixture of molten copper sulfide and iron sulfide
produced in the reverberatory or electric furnace during
smelting which is suitable for subsequent treatment in
converters.
Matte Smelting
A process in which the concentrated ore, other
copper-bearing material, and fluxing material are melted at
furnace temperatures of 1090 to 1650 C (2000 to 3000 F),
producing a liquid slag primarily composed of iron silicate
which floats above a molten matte composed primarily of iron
and copper sulfides, and the matte, still liquid, is charged
to converters.
Mill-Cpncentrator
The common name given to the facility where the steps of the
concentration process (i.e., crushing, grinding, flotation,
thickening, and filtering) are performed.
Native Copper Metal
Mineral whose composition is 100 percent elemental copper.
The native copper ore, significant only in Upper Michigan,
contains about 1 percent native copper metal.
New_source
Any building, structure, facility, or installation from
which there is or may be a discharge of pollutants and whose
construction is commenced after the publication of the
proposed regulations.
207
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New Source Perforrra nce Standards
Performance standards for the industry and applicable new
sources as defined fcy Section 306 of the Act,
Operating and Maintenance costs
Costs required to operate and maintain pollution abatement
equipment, including labor, material, insurance, taxes,
solid waste disposal, etc.
A measure of the alkalinity or acidity of a solution,
numerically equal to 7 for neutral solutions, increasing
with increasing alkalinity and decreasing with increasing
acidity. A one unit change in pH indicates a tenfold change
in acidity or alkalinity.
Point Source
A single source of water discharge such as an individual
plant.
Poling
A process used in fire-refining that consists of the
introduction of poles of green wood into the molten metal so
as to generate gases that have a reducing action on the
cuprous oxide.
Pollutant Parameters
Those constituents of waste water determined to be
detrimental and therefore requiring control.
Pregnant Liquor
Solution containing the metal values prior to their removal
and recovery.
A process to remove substantially all floating and
208
-------
settleable solids in waste water and partially to reduce the
concentration of suspended solids.
Process^Effluent or Discharge
The volume of water emerging from a particular use in the
plant.
Refinery
The building and equipment used for the electrolytic
refining of copper. While a fire-refinery may also be at
the site, the term refers to the electrolytic refinery.
Refinery Shapes
The final castings made after melting the cathodes con-
taining the copper plated out during electrolytic refining.
These shapes include tars/ cakes, billets, ingots, and new
cathode starter sheets.
Reverberatory Furnace
A continuous process furnace, in which the flame enters the
end and passes upward, striking the arched roof, and is then
reverberated downward upon the charge. The interiors of
reverberatory furnaces range from 27 to 40 m (90 to 130 ft)
long and 5.5 to 9m (18 to 30 ft) wide, and are less than 6
m (20 ft) deep.
A nonfusion process carried out in either multiple^hearth
furnaces or in fluid-bed roasters to- dry the concentrates,
oxidize a portion of the sulfur from the ore, and remove
impurities such as arsenic, antimony, and selenium. The
object of roasting is to control ^.he amount of sulfur in the
concentrate fed to the reverberatory or electric furnace.
Roasting is bypassed at some present-day smelters (i.e.,
green-feed smelters).
Secondary Treatment
A process to reduce the amount of dissolved organic matter
209
-------
and further reduce the amount of suspended solids in waste
water.
Slime
The insoluble impurities, including precious metals, that
leave the anode during electrolytic refining and settle to
the bottom of the tank as mud. Also, the fine powder
produced in grinding the ore as opposed to the coarse
granules or sands.
Smelter
An establishment for melting or fusing the copper ore with
an accompanying chemical change to separate the copper from
other impurities. Matte smelting and converting are
essential processes at a smelter, while roasting and fire-
refining may also be done there. Facilities for conducting
electrolytic refining, concentrating, and mining may be
integrated with the smelting operation.
In the general sense, smelting can be used to cover the
successive operations of roasting, matte smelting, and
converting. In the particular sense, it refers to matte or
reverberatory smelting, a process generally done in a
reverberatory furnace.
Solvent Extraction
Technique for recovering copper from leach solutions by
first mixing the pregnant leach liquor with an organic
solvent, which extracts the copper into an organic phase,
and then mixing the resultant copper-organic solution with
an aqueous stripping solution that causes the copper to
enter the stripping pnase from which it can be recovered by
electrolysis. The leach, extraction, and stripping phases
are characterized by the recycling of the leach liquor,
organic solvent, and stripping scluticn, respectively. The
solvent extraction process produces a higher quality
finished product than cement copper.
Standard of Performance
A maximum weight discharged per unit of production for each
210
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constituent that is subject to limitation and applicable to
new sources, as opposed to existing sources, which are
subject to effluent limitations.
Surface Waters
Navigable waters. The waters of the United States including
the territorial seas.
MULTIPLY (ENGLISH UNITS)
ENGLISH UNIT ABB]
acre a<
acre - feet a<
British Thermal
Unit K
British Thermal
Unit/pound H
cubic feet/minute c3
cubic feet/second cJ
cubic feet ci
cubic feet ci
cubic inches a
degree Fahrenheit %J
feet f1
gallon gj
gallon/minute gj
horsepower hj
inches ii
inches of mercury ir
pounds U
million gallons/day me
mile mj
pound/square
inch (gauge) ps
square feet sc
square inches sc
ton (short) tc
yard yc
* Actual conversion, not e
Tailings
The gangue and other refuse material resulting from the
washing, concentrating or treatment of the crushed and
ground ore.
Tank House
Building that houses the electrolytic cells, storage tanks,
and pumps. A typical refinery of 16,000 tons per month may
have 1200 electrolytic cells in a building approximately 180
x 120 m (600 by 400 ft) .
Thickener
A cylindrical tank with submerged rotating rakes used in
several steps of copper concentrating to separate clear
water from solids by sedimentation and decantation.
Total Suspended Solids _(TSS}
Solids found in waste water or in the stream, which in most
cases can be removed by filtration. The origin of suspended
matter may be man-made or natural sources, such as silt from
erosion.
A nozzle or port through which an
into a furnace.
air blast is delivered
Unit Operation
A single, discrete process as part of an overall sequence
(e.g., precipitation, settling, filtration).
211
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Wet Scrubber
A unit in which
by a liquid.
sprays, bubble c
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U.S. ENVIRONMENTAL PROTECTION AGENCY (A-107)
WASHINGTON. D.C. 20460
POSTAGE AND FEES PAID
ENVIRONMENTAL PROTECTION AGENCY
EPA-335
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