PRELIMINARY DRAFT
ASSESSMENT OF SOLID WASTE MANAGEMENT
PROBLEMS AND PRACTICES
IN NONFERROUS SMELTERS
PEDCo ENVIRONMENTAL
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PEDCO ENVIRONMENTAL. INC.
ASSESSMENT OF SOLID WASTE MANAGEMENT
PROBLEMS AND PRACTICES
IN NONFERROUS SMELTERS
Prepared by
PEDCo Environmental, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
Contract No. 68-03-2577
Prepared for
EPA Technical Project Monitor
John O. Burckle
Metals and Inorganic Chemicals Branch
IERL - Cincinnati
Office of Research and Development
In Cooperation with
Special Wastes Branch
Industrial Waste Program
Jon Perry, Coordinator
Systems Management Division
Office of Solid Waste
U.S. ENVIRONMENTAL PROTECTION AGENCY
1 1499 CHESTER ROAD
CINCINNATI, OHIO 45246
(513) 782-4700
TELEX (513) 782-4807
PRELIMINARY DRAFT
Washington, D.C
March 13, 1979
TOWERS
DALLAS. TEXAS
KANSAS CITY. MISSOURI
BRANCH OFFICES
COLUMBUS. OHIO
DURHAM. NORTH CAROLINA
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ACKNOWLEDGMENT
This report deals with solid waste generation and management
at domestic nonferrous metal smelters and refineries. The study,
conducted by PEDCo Environmental, Inc., Cincinnati, Ohio, under
\
Contract No. 68-03-2577, is one of a series of assessments of
industrial solid wastes being conducted for the EPA Office of
Solid Waste (OSW), to provide support for implementation of P. L.
94-580, the Resource Conservation and Recovery Act of 1976
(RCRA).
The EPA Project Officers were Jon Perry of the Office of
Solid Waste Management Programs and John Burckle of the Indus-
trial Environmental Research Laboratory. Their guidance and
advice throughout the project are gratefully acknowledged.
The PEDCo project director was Robert S. Amick, the project
manager was Jack S. Greber. Principal investigators and authors
were Robert S. Amick, Jack S. Greber, Robert L. Hoye, Craig R.
Jones, Dave W. Sass, Mary A. Taft, and A. Christian Worrell, III.
Several Federal and state governmental agencies provided
valuable data. These agencies and the personnel who provided
helpful input are identified in Appendix A.
Finally, the cooperation of trade associations and metall-
urgical companies and their representatives who provided
pertinent information is gratefully acknowledged.
ii
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CONTENTS
Page
ACKNOWLEDGMENT ii
TABLES . v
FIGURES xi
CONVERSION FACTORS AND SI UNITS xiiii
EXECUTIVE SUMMARY xiv
1 INTRODUCTION 1-1
2 ALUMINUM INDUSTRY 2-1
Industry Characterization 2-1
Solid Waste Characterization 2-24
Solid Waste Control Practices and Costs .... 2-56
References for Section 2 2-101
3 COPPER INDUSTRY 3-1
Industry Characterization 3-1
Solid Waste Characterization 3-30
Solid Waste Control Practices and Costs .... 3-65
References for Section 3 3-109
4 PRIMARY LEAD SMELTING AND REFINING INDUSTRY . . . 4-1
Industry Characterization 4-1
Solid Waste Characterization 4-25
Solid Waste Control Practices and Costs .... 4-46
References for Section 4 4-84
iii
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CONTENTS
Page
5 PRIMARY ZINC SMELTING AND REFINING INDUSTRY . . . 5-1
Industry Characterization 5-1
Solid Waste Characterization 5-23
Solid Waste Control Practices and Costs .... 5-46
References for Section 5 5-84
6 MINOR PRIMARY AND SECONDARY NONFERROUS
SMELTING AND REFINING INDUSTRIES 6-1
Solid Waste Characterization 6-2
Alternative Controls and Costs 6-17
References for Section 6 6-19
Appendix A A-l
Appendix B B-l
Appendix C C-l
Capital Costs C-2
Annual Costs C-ll
iv
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LIST OF TABLES
No. Title Page
2-1 U.S. Primary Aluminum Industry Statistics 2-6
2-2 U.S. Primary Aluminum Producers 2-9
2-3 Annual Solid Waste Production at Primary Aluminum
Plants Represented by Model 1 2-33
2-4 Annual Solid Waste Production at Primary Aluminum
Plants Represented by Model 2 2-39
2-5 Annual Solid Waste Production at Primary Aluminum
Plants Represented by Model 3 2-44
2-6 1978 National Solid Waste Totals for the Primary
Aluminum Smelting Industry 2-4 5
2-7 Geographical Distribution of Solid Waste From the
Primary Aluminum Smelting Industry 2-47
2-8 Projected Solid Waste From the Primary Aluminum
Smelting Industry 2-48
2-9 Total Annual Sludge From Aluminum Smelting Attrib-
utable to Air and Water Quality Regulations . . . 2-51
2-10 Analysis for Potentially Hazardous Solid Wastes
From the Primary Aluminum Smelting Industry . . . 2-54
2-11 Total Cost of Current Controls for Model 1:
Aluminum Plants With Dry Scrubbing ....... 2-65
2-12 Total Cost of Current Solid Waste Controls for
Model 2: Aluminum Plants With Wet Scrubbing . . 2-7 0
2-13 Total Cost of Current Solid Waste Controls for
Model 3: Aluminum Plants With Both Wet and Dry
Scrubbing 2-7 3
2-14 Total Cost of Current Solid Waste Control for the
Primary Aluminum Smelting Industry 2-74
2-15 Total Cost of Alternative Solid Waste Controls for
Model 1: Aluminum Plants With Dry Scrubbing . . 2-84
2-16 Total Cost of Alternative Solid Waste Controls for
Model 2: Aluminum Plants With Wet Scrubbing . . 2-88
v
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LIST OF TABLES (cont.)
No. Title Page
2-17 Total Cost of Alternative Solid Waste Disposal
Controls for Model 3: Aluminum Plants With Both
Wet and Dry Scrubbing 2-91
2-18 Total Cost of Alternative Solid Waste Controls For
the Primary Aluminum Smelting Industry 2-92
2-19 Total Cost of Closing Existing Solid Waste Control
Sites for the Primary Aluminum Smelting Industry 2-96
2-20 Current, Alternative, Closure, and Incremental
Control Costs for the Primary Aluminum Smelting
Industry 2-97
2-21 Criteria-Induced Control Costs for the Primary
Aluminum Smelting Industry 2-99
3-1 U.S. Primary Copper Industry Statistics 3-5
3-2 U.S. Primary Copper Producers 3-7
3-3 Annual Solid Waste Production at Primary Copper
Plants Represented by Model 1 3-36
3-4 Annual Solid Waste Production at Primary Copper
Plants Represented by Model 2 3-43
3-5 Annual Solid Waste Production at Primary Copper
Plants Represented by Model 3 3-47
3-6 Annual Solid Waste Production at Primary Copper
Plants Represented by Model 4 3-49
3-7 Annual Solid Waste Production at Primary Copper
Plants Represented by Model 5 3-54
3-8 1978 National Solid Waste Totals for the Primary
Copper Smelting and Refining Industry 3-55
3-9 Geographical Distribution of Solid Wastes From the
Primary Copper Smelting and Refining Industry . . 3-56
3-10 Projected Solid Waste From the Primary Copper
Smelting and Refining Industry 3-57
3-11 Total Annual Sludge From Copper Smelting and
Refining Attributable to Air and Water Quality
Regulations 3-60
vi
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LIST OF TABLES (cont.)
No. Title Page
3-12 Typical Furnace Slag Analysis 3-62
3-13 Typical Acid Plant Blowdown Waste Characterization 3-64
3-14 Total Cost of Current Solid Waste Controls for
Model 1: Reverberatory Smelting 3-72
3-15 Total Cost of Solid Waste Controls for Model 2:
Electric Smelting 3-74
3-16 Total Cost of Current Solid Waste Controls for
Model 3: Noranda Smelting 3-76
3-17 Total Cost of Current Solid Waste Controls for
Model 4: Flash Smelting 3-79
3-18 Total Cost of Current Solid Waste Controls for
Model 5: Electrolytic Refining 3-81
3-19 Total Cost of Current Solid Waste Controls for the
Primary Copper Smelting and Refining Industry . . 3-82
3-20 Cost of Alternative Solid Waste Controls for
Model 1: Reverberatory Smelting 3-93
3-21 Cost of Alternative Solid Waste Controls for
Model 2: Electric Smelting 3-94
3-22 Cost of Alternative Solid Waste Controls for
Model 3: Noranda Smelting 3-96
3-23 Cost of Alternative Solid Waste Controls for
Model 4: Flash Smelting 3-98
3-24 Cost of Alternative Solid Waste Controls for
Model 5: Electrolytic Refining 3-99
3-25 Total Cost of Alternative Solid Waste Controls for
the Primary Copper Smelting and Refining Industry 3-100
3-26 Total Cost of Closing Existing Disposal Sites for
the Primary Copper Smelting and Refining Industry 3-103
3-27 Current, Alternative, Closure, and Incremental
Control Costs for the Primary Copper Smelting and
Refining Industry 3-104
vii
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LIST OF TABLES (cont.)
No. Title Page
3-28 Criteria-Induced Control Costs for Primary Copper
Smelting and Refining Industry 3-107
4-1 U.S. Primary Lead Industry Statistics 4-6
4-2 U.S. Primary Lead Producers 4-7
4-3 Annual Solid Waste Production at Primary Lead
Plants Represented by Model 1 4-32
4-4 Annual Solid Waste Production at Primary Lead
Plants Represented by Model 2 4-37
4-5 1978 National Solid Waste Totals for the Primary
Lead Smelting and Refining Industry 4-38
4-6 Geographical Distribution of Solid Waste From the
Primary Lead Smelting and Refining Industry . . 4-39
4-7 Projected Solid Waste From the Primary Lead
Smelting and Refining Industry 4-41
4-8 Total Annual Sludge From Lead Smelting and Refining
Attributable to Air and Water Quality Regulations 4-43
4-9 Typical Analysis of Lead Blast Furnace Slag . . . 4-45
4-10 Total Cost of Current Controls for all Plants
Represented by Model 1 4-54
4-11 Total Cost of Current Controls for all Plants
Represented by Model 2 4-55
4-12 Total Cost of Current Solid Waste Control for the
Primary Lead Smelting and Refining Industry . . 4-62
4-13 Cost of Alternative Solid Waste Control for all
Plants Represented by Model 1 4-67
4-14 Cost of Alternative Solid Waste Control for all
Plants Represented by Model 2 4-68
4-15 Total Cost of Alternative Solid Waste Controls in
the Primary Lead Smelting and Refining Industry 4-75
4-16 Total Cost of Closing Existing Control Sites in
the Primary Lead Smelting and Refining Industry 4-78
viii
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LIST OF TABLES (cont.)
No. Title Page
4-17 Current, Alternative, Closure, and Incremental
Control Costs for the Primary Lead Smelting and
Refining Industry 4-79
4-18 Criteria-Induced Control Costs for the Primary Lead
Smelting and Refining Industry 4-82
5-1 U.S. Primary Zinc Industry Statistics 5-5
5-2 U.S. Primary Zinc Producers 5-7
5-3 Annual Solid Waste Production at Primary Zinc Plants
Represented by Model 1 5-29
5-4 Annual Solid Waste Production at Primary Zinc Plants
Represented by Model 2 5-35
5-5 1978 National Solid Waste Totals for the Primary
Zinc Smelting and Refining Industry 5-36
5-6 Geographical Distribution of Solid Waste From the
Primary Smelting and Refining Industry 5-38
5-7 Projected Solid Waste From the Primary Zinc Smelting
and Refining Industry 5-39
5-8 Total Annual Sludge From Zinc Smelting and Refining
Attributable to Air and Water Regulations .... 5-41
5-9 Typical Zinc Furnace Residue Analysis 5-45
5-10 Total Cost of Current Solid Waste Controls for
Model 1: Electrolytic Zinc Plants 5-56
5-11 Total Cost of Current Solid Waste Controls for
Model 2: Pyrometallurgical Zinc Plants 5-60
5-12 Total Cost of Current Solid Waste Controls for the
Primary Zinc Smelting Industry 5-62
5-13 Total Cost of Alternative Solid Waste Controls for
Model 1: Electrolytic Zinc Plants 5-69
5-14 Total Cost of Alternative Solid Waste Controls for
Model 2: Pyrometallurgical Plants 5-74
5-15 Total Cost of Alternative Solid Waste Controls for
the Primary Zinc Smelting Industry 5-75
ix
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LIST OF TABLES (cont.)
No. Title Page
5-16 Total Cost of Closing Existing Solid Waste Disposal
Sites for the Primary Zinc Smelting Industry . . 5-78
5-17 Current, Alternative, Closure, and Incremental
Control Costs for the Primary Zinc Smelting
Industry 5-80
5-18 Criteria-Induced Control Costs for the Primary
Zinc Smelting Industry 5-83
6-1 Waste Generation Factors for Minor Primary and
Secondary Nonferrous Metals Industries 6-4
6-2 Annual Metal Production and Solid Waste Generation
by Minor Primary and Secondary Nonferrous Metals
Industries 6-5
x
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LIST OF FIGURES
No. Title Page
2-1 Flow chart depicts primary aluminum smelting
(numbers correspond to process numbers in text) . . 2-17
2-2 In the primary aluminum industry Model 1
represents plants with dry scrubbing 2-28
2-3 In the primary aluminum industry Model 2
represents plants with wet scrubbing 2-34
2-4 In the primary aluminum industry Model 3 represents
plants with both wet and dry scrubbing 2-40
3-1 Flow chart depicts primary copper smelting and
refining (numbers correspond to process numbers
in text) 3-16
3-2 In the primary copper industry Model 1 represents
plants with reverberatory smelting 3-34
3-3 In the primary copper industry Model 2 represents
plants with electric smelting 3-41
3-4 In the primary copper industry Model 3 represents
plants with modified Noranda smelting 3-44
3-5 In the primary copper industry Model 4 represents
plants with flash smelting 3-48
3-6 In the primary copper industry Model 5 represents
plants with electrolylic refining and slimes
treatment 3-51
4-1 Flow chart depicts primary lead smelting and
refining (numbers correspond to process numbers
in text) 4-13
4-2 In the primary lead industry Model 1 represents
Missouri smelting and refining 4-28
4-3 In the primary lead industry Model 2 represents
non-Missouri smelting and refining 4-33
5-1 Flow chart depicts primary zinc smelting and refining
(numbers correspond to process numbers in text) . . 5-13
xi
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LIST OF FIGURES
No. Title Page
5-2 In the primary zinc industry Model 1 represents
electrolytic plants 5-25
5-3 In the primary zinc industry Model 2 represents
pyrometallurgical plants 5-30
xii
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To convert
Inches (in.)
Feet (ft)
Miles (statute)
Square feet (ft2)
Acres
Cubic feet (ft3)
3
Cubic yards (yd )
Gallons (gal)
Gallons (gal)
Troy ounces (oz)
Pounds (lb)
Tons (short)
CONVERSION FACTORS
To
Centimeters (cm)
Meters (m)
Kilometers (km)
2
Square meters (m )
Hectares (ha)
3
Cubic meters (m )
3
Cubic meters (m )
3
Cubic meters (m )
Liters
Grams (g)
Kilograms (kg)
Megagrams (Mg)
SI PREFIXES
Factor by which unit
is multiplied Prefix
10^ tera
10 giga
10 mega
103 kilo
102 hecto
10 deka
10 1 deci
10 2 centi
10 3 milli
m-6
10 micro
m-9
10 nano
in" 12
10 pico
10 ^ femto
— 1ft
10 ia atto
Multiply by
2.540
0.3048
1.609
0.0929
0.4047
0.0283
0.7645
0.003785
3.785
31.103
0.4537
0.907
Symbol
T
G
M
k
h
da
d
c
m
M
n
P
f
a
xiii
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EXECUTIVE SUMMARY
Study Background
The ultimate disposal of industrial solid wastes on the land
in an environmentally sound manner is a rapidly increasing
problem. The adverse environmental and economic impacts of
disposal facilities that are improperly located, designed,
operated, monitored, and controlled are sure to increase unless
sound control practices are followed. The severity of problems
associated with industrial solid waste disposal results from
several factors. First, more wastes are being disposed of on the
land in response to population increases, economic growth, and
affluence. In addition, legislative mandates are causing greater
production of solid wastes by requiring more stringent control of
air and water pollutants.
Most industrial solid waste disposal facilities in the
United States are uncontrolled, especially for protection of
groundwaters. Solid waste disposal sites are seldom monitored,
dumping is often indiscriminate, and there is no effective
Federal legislation for protection of groundwaters from solid
waste leachate.
The effort to abate these problems of industrial solid waste
disposal requires background information with which to identify
xiv
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and define the specific solid waste problems of various
industries. This report deals with solid waste generation and
management at domestic nonferrous metal smelters and refineries.
The study is one of a series of assessments of industrial solid
wastes being conducted for the EPA Office of Solid Waste (OSW) to
provide support for implementation of P.L. 94-580, the Resource
Conservation and Recovery Act of 1976 (RCRA). These studies are
being conducted for informational purposes only and not in
response to congressional mandate.
The Resource Conservation and Recovery Act of 1976 is an
amendment to a prior statute, the Solid Waste Disposal Act of
1965. The main purpose of the act is to ensure that solid wastes
are managed so as to prevent damage to public health and the
environment. The act deals with hazardous wastes (Subtitle C)
and nonhazardous wastes (Subtitle D). Although this study is
concerned with Subtitle D, and emphasizes nonhazardous wastes, it
addresses all of the solid wastes associated with nonferrous
metal smelters and refineries because the distinction between
hazardous and nonhazardous wastes is not clear-cut. Definition
of hazardous and nonhazardous wastes for this study is based on
lists given in the Federal Register of December 18, 1978. It is
important to note that the final regulations and guidelines may
be different from those on which the 1978 list is based.
The RCRA requires that EPA provide criteria to be used by
the states in identifying practices that constitute the open
dumping of solid wastes. It also requires that EPA provide
xv
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criteria for determining which solid waste disposal facilities do
and which do not "pose a reasonable probability of adverse
effects on health or the environment."* As part of a broad-based
effort undertaken to fulfill these requirements EPA has
commissioned this study of solid waste disposal in the nonferrous
metals industry. The report resulting from the study provides
(1) a data base on the type and quantity of wastes generated and
the treatment and disposal techniques now applied for their
control; (2) a basis for planning of technical assistance
activities; (3) the background information needed to develop a
long-term strategy for Federal policies concerning solid wastes
from nonferrous metal smelters and refineries. The report also
provides information concerning the costs to industry of meeting
the RCRA 4004 Criteria. The Criteria-induced costs are the
additional costs above current costs of solid waste control that
will be incurred in bringing existing facilities into compliance
with the Criteria.
This study covers the smelting and refining portions of the
nonferrous metals industry, that is, the operations that process
concentrated ores from the mining and beneficiating segments of
this industry. The most important nonferrous metals industries
* In the February 6, 1978, Federal Register (43 Fed. Reg.
4942), EPA proposed "Criteria for the Classification of Solid
Waste Disposal Facilities" (40 CFR Part 257). These proposed
regulations are referred to in this report as "the Criteria."
xv i
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in terms of number of operations and quantity of material handled
are the primary aluminum, copper, lead, and zinc industries. The
minor, primary metals industries (e.g. antimony, beryllium,
titanium) and the secondary metals industry are far less
important from the standpoint of size, geographic distribution,
quantity of wastes generated, and environmental impacts. For
these reasons, the primary aluminum, copper, lead, and zinc
industries are emphasized and the other industries are assessed
briefly. The analysis covers only the smelting portion of the
primary aluminum industry because the refining segment is
addressed in another industrial solid waste project being
conducted for EPA.
Many of the operations associated with production of
nonferrous metals generate solid wastes. The wastes include, for
example, inorganic slags from smelters, electrolytic slimes,
sludges from electrolytic regeneration and purification, fumes
and particulate matter captured in air pollution control
equipment, acid plant blowdown, worn-out mechanical trash, and
water treatment sludges.
Study Approach
The approach to this study was to acquire, compile, and
analyze as much available information as possible concerning the
generation, control, regulation, and environmental effects of
solid wastes from the nonferrous metals industry. This
information was then used to generate a data base report that
xvii
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formed the basis for the technical study and report. Data
gathering consisted of four major tasks, each concerned with a
particular information source: (1) a literature search for
published and unpublished information; (2) contacts with
governmental agencies whose responsibility includes the
metallurgical industry and/or effects of the industry (Appendix A
lists the agencies and personnel contacted); (3) contacts with
five trade associations that provided industry contacts,
furnished answers to general and specific questions, and helped
arrange visits to industrial sites; (4) visits to smelters and
refineries to obtain specific data on operations and solid wastes
and to solicit comment from industry personnel.
Methodology
For each of ttie four major primary nonferrous metals
industries (aluminum, copper, lead, and zinc), this study
provides an industry characterization, a solid waste
characterization, and an analysis of solid waste control
practices and costs. The methods used in collecting, evaluating,
and presenting these data are described below, together with the
basic assumptions and methods used in estimating solid waste
control costs.
Industry Characterization
Each industry is described in terms of raw materials,
production/capacity (includes product prices), companies
(includes number of firms and plants, location, distribution, and
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employment), energy consumption, and outlook (economic and
technological). Process information describing the various
operations currently used in each industry is also provided.
The industry descriptions are based on publications of the
U.S. Bureau of Mines, including the Mineral Commodity Summaries,
Mineral Facts and Problems, and the Minerals Yearbook.
Additional information was obtained from a variety of other
published sources including the Engineering and Mining Journal,
Journal of Metals, Mining Congress Journal, and the 1977
Nonferrous Metals Data Booklet. Specialists in various metal
categories from the U.S. Bureau of Mines supplied some industry
information, particularly concerning operations on which
published data are sparse for proprietary reasons. Information
gleaned from site visits, trade association contacts, and PEDCo
files was also useful.
Solid Waste Characterization
The solid waste characterizations of the four major
industries are based on model plants developed to represent the
different processes within each of these industries. A model
plant approach was followed because the scope and time schedule
of this project did not permit the assessment of each individual
plant. It is believed that the model plants provide a valid
representation of the industries because of the detailed
consideration given in developing the models for each industry:
three models for aluminum (for plants with wet scrubbing, plants
with dry scrubbing, and plants with both wet and dry scrubbing);
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five models for copper (for reverberatory smelting, electric
smelting, flash smelting, Noranda smelting, and electrolytic
refining); two models for lead (for Missouri and non-Missouri
smelting and refining operations); two models for zinc (for
pyrometallurgical and electrolytic operations).
Solid waste quantities are calculated and presented as solid
waste generation factors for each type of waste in each model,
expressed in tons per ton of metal product produced. The factors
represent average values calculated mostly from data obtained
during site visits. Incomplete data were supplemented with
published information or with values obtained in telephon^
contacts with industry personnel.
The waste generation factors were used to estimate total
solid waste quantities based on the total metal production of all
plants represented by a model. The solid waste quantities were
then used to estimate state, EPA region, and national solid waste
totals. It is important to note that the solid waste statistics
do not include residuals from devices used in air and water
pollution control when these residuals are either directly
recycled to the process or sent elsewhere for metal recovery
after temporary onsite storage.
The qualitative description of solid wastes is based
primarily on information obtained from the literature; some
valuable data were also supplied by industry personnel during
site visits. This study included no sampling and analysis of
solid wastes.
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Solid Waste Control Practices and Costs
The analysis considers both current and alternative solid
waste control practices. The current practices are those used
most commonly in the industry. The alternative practices are
improved methods of handling, disposal, and control that may be
required under RCRA to ensure adequate protection of human health
and environment. The alternative controls specified herein are
based on contractor investigations and professional judgment.
The RCRA nonhazardous waste Criteria were used as guidelines in
developing the alternative controls, with consideration for both
technical and economic feasibility. The alternative controls are
not to be considered as operational guidelines or standards that
industry should be required to follow, but rather they represent
the level of control that would be expected to satisfy RCRA
criteria.
In addition to the expenses incurred in implementing the
alternative controls, industry may have to absorb other costs in
complying with RCRA. These additional expenses include the cost
of closing disposal sites when the period of operation has ended
and of maintaining and monitoring the sites for 20 years after
closure. For this study it is assumed that all existing onsite
disposal facilities fail to meet RCRA criteria, that these will
be closed rather than upgraded to meet RCRA requirements, and
that new onsite disposal facilities will be constructed.
All solid waste control costs are based on a facility life
of 20 years. It is assumed that waste disposal starts at the
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point where the waste is generated and therefore equipment for
handling and transporting the wastes is assumed to be part of the
waste control systems. Procedures such as site selection, site
preparation, and monitoring are also considered as part of the
controls, and they may be required under RCRA to ensure adequate
protection of human health and the environment.
The unit or incremental cost factors and the methods used in
developing capital and annual costs of waste control systems and
closure are documented in Appendix C. The costs presented
throughout this report are computed as described in that appendix
unless it is specifically noted otherwise. All costs are in 1978
dollars.
The incremental costs of controlling nonhazardous wastes are
grouped into two categories: state-standard-induced costs (cost
of compliance with existing state standards) and Criteria-induced
cost (cost beyond those needed to achieve compliance with state
standards). This breakdown is necessary because some disposal
sites do not yet comply with current state standards. The
Criteria-induced costs are presented on a state-by-state basis.
Summary of Findings
The major findings of this study are summarized in the
following pages. The first portion of the summary is an
evaluation of the four major industries emphasized in this study
(aluminum, copper, lead, and zinc). Each evaluation consists of
an industry characterization, a solid waste characterization, and
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an assessment of solid waste control practices and costs. The
last portion of this summary is an evaluation of the minor
primary and secondary nonferrous metals industries.
Industry Characterization
The United States is a major producer and consumer of
primary aluminum, copper, lead, and zinc. These industries,
however, are faced with serious problems, which they must deal
with effectively if they are to continue to compete in the
international market and protect this Nation's consumers against
total reliance on imports of these important metals. Foremost
among these problems are environmental regulations and associated
compliance costs, transportation costs, depressed domestic
markets, labor strikes, and oversupply at some plants. The
primary aluminum industry faces several other problems. First,
the U.S. reserves of bauxite (an aluminum-containing ore) are
inadequate to meet domestic needs. Domestic aluminum smelters
therefore depend heavily on imported bauxite, and the producing
countries have raised prices rapidly in recent years. Another
major problem is the shortage of low-cost energy. Aluminum
production requires considerable amounts of both electrical and
thermal energy, and although most facilities have been located to
take advantage of inexpensive sources of fossil fuels, the
rapidly increasing costs and potential shortages of these fuels
could profoundly affect the ability of the industry to produce a
competitively priced product.
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The primary copper, lead, and zinc industries consist of
mining, concentrating, smelting, and refining segments.
Generally, ore is mined and concentrated at one location and then
shipped to nearby smelters for production of metal. The smelted
metal is purified further at the refinery. Refinery operations
are located onsite at many of the large smelter facilities; other
smelters must ship the metal to a centrally located refinery for
final purification. Some of the larger primary metal-producing
companies are vertically integrated and therefore are involved in
all of the segments of the industry (mining, concentrating,
smelting, and refining). Several of the larger primary copper
producers are vertically integrated to operate all the mining and
processing segments at the same general location.
Production of primary aluminum is similar to that of primary
copper, lead, and zinc in that it consists of four distinct
segments: mining, beneficiating, refining, and smelting. It
differs from these other industries, however, in that refining
precedes rather than follows smelting. The refining operation
removes virtually all impurities from the aluminum-containing ore
(bauxite) and yields a calcined alumina that is reduced to
aluminum metal at the smelter.
The primary aluminum, copper, lead and zinc industries are
typified by a relatively small number of plants with high
production capacities (Table I). The largest is the primary
aluminum industry, which consists of 12 companies operating a
total of 30 plants. Primary domestic aluminum production in 1977
xx iv
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TABLE I
CHARACTERISTICS OF THE U.S. PRIMARY ALUMINUM, COPPER,
LEAD, AND ZINC
INDUSTRIES
Industry
category
NO. Of
plants*
Total 1977 primary
production (tons)
Estimated 1977 total
production value (million dollars)
Aluminum'''
30
4,539,000
4,600
Copper ®
27
1,600,000
214
Lead"
7
611,650
370
Zinc®
7
500,000
326
* Number of plants includes both smelters and refineries except for
aluminum, which includes smelters only.
^ Sources: Aluminum industry in June 1977. Mineral Industry Surveys.
U.S. Department of the Interior, Bureau of Mines, Washington, D.C. September
28, 1977.
Primary aluminum plants, worldwide, Part one. U.S. Department of the
Interior, Bureau of Mines, Denver. August 1977.
^ Sources: Schroeder, H.J. Copper. Mineral Commodity Profile-3. U.S.
Department of the Interior, Bureau of Mines, Washington, D.C. June 1977. _
Copper in 1977. Mineral Industry Surveys. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C. March 1978.
' Refined metal mineral industry surveys. Lead industry in May 1978.
U.S. Department of the Interior, Bureau of Mines, Washington, D.C. August
1978.
@ Zinc industry in June 1978. Mineral Industry Surveys. U.S. Depart-
ment of the Interior, Bureau of Mines, Washington, D.C. September 6, 1978.
Note. Metric conversion table is given in front matter.
XXV
-------
was 4.5 million tons (4.1 Tg), with a value of $4.6 billion.
These figures indicate that the industry utilized about 92
percent of total plant capacity.
The next largest is the primary copper industry, which
consists of 11 companies that operate 16 primary smelters and 11
primary refineries. In 1977 this industry operated at about 70
percent of total plant capacity in producing 1.6 million tons
(1.5 Tg) of refined copper with a value of $214 million.
The primary lead and zinc industries each consist of seven
plants. In 1977 the lead and zinc industries produced 611,650
tons (554.8 Gg) and 500,000 tons (453.6 Gg) with values of $370
and $326 million. These production figures indicate that each of
these industries used about 75 percent of total plant capacity.
Solid Waste Characterization
With some variations at individual plants, both the sources
and quantities of solid wastes are similar in the various
nonferrous metals industries. The major waste categories are
process wastes from the main smelting and refining operations,
process wastes from auxiliary operations (at some but not all
facilities), miscellaneous slurries and sludges from sources such
as plant washdown and cooling waters, and slurries from air and
water pollution control devices. Residuals from air and water
pollution control that are recycled or treated for metal recovery
are not considered as solid wastes in this study.
Total solid waste quantities are estimated for each industry
by applying average waste generation factors to the metal
xxvi
-------
production data. The generation factors, given in tons of waste
per ton of metal product (Table II), were calculated mostly from
data obtained during plant visits and supplemented by published
data.
Some of the solid wastes produced by the nonferrous metals
industry are considered, at least at this time, to be hazardous
(Table II), according to EPA's list of hazardous wastes in the
Federal Register of December 18, 1978 (43 Fed. Reg. 58946). The
list is based on tests conducted by EPA and private contractors;
it will undoubtedly change as the results of more field and
laboratory tests become available. The burden of proof as to
whether a waste is nonhazardous or hazardous will eventually fall
on industry. For purposes of this study, all wastes not listed
in the December 18, 1978, Fecteral Register are considered as
nonhazardous.
The total generation of all solid wastes by the primary
aluminum, copper, lead, and zinc industries in 1978 was 4.7
million tons (4.3 Tg). According to the current EPA list, 15.2
percent [721,650 tons (654.6 Gg)] of this total is considered to
be hazardous waste. The remaining 84.8 percent [4 million tons
(3.6 Tg)] is considered in this study to be nonhazardous.
The largest producer of solid waste within the nonferrous
metals industry is the primary copper industry, which generated
some 2.5 million tons (2.3 Tg) of nonhazardous waste and 615,150
tons (558 Gg) of hazardous waste in 1978. The largest single
source of nonhazardous waste in the copper industry is slag from
xxv ii
-------
TABLE II
SOLID WASTE GENERATION FACTORS AND ESTIMATED 1978 SOLID WASTE STATISTICS
FOR THE PRIMARY NONFERROUS METALS INDUSTRY*
Metal
Category
Waste type
Waste generation
factor (tons/ton of product)t
1978 Solid
Total
generated?
waste generation statistics (tons)
Total potentially Total
hazardous' Nonhazardous1
Primary
Potliners
0.037
168,000
0
168,000
aluminum
Scrap brick
0.032
106,000
0
106,000
smelting
Shotblast dusts
0.005
16,000
0
16,000
Casthouse dusts
0.025
12,000
0
12,000
Scrubber sludge
0.037-0.073
149,000
0
149,000
Industry total
451,000
0
451,000
Primary copper.
Reverb, furnace
smelting and
slag
2.4
1,842,000
0
1,842,000
fire refining
Electric furnace
slag
2.3
605,500
605,000
0
Noranda furnace
slag
2.2
351,000
0
351,000
Flash furnace
slag
2.7
311,000
0
311,000
Acid plant
blowdown
0.003
9,650
9,650
0
Miscellaneous
0.017?
slurries
24,300
0
24,300
Primary copper,
Miscellaneous
0.002?
electrolytic
slurries
3,200
0
3,200
refining
Industry total
3,146,650
615,150
2,531,500
Primary lead,
Furnace slag
0.38
142,600
0
142,600
Missouri plants
Miscellaneous
0.07?
slurries
46,900
46,900
0
Primary lead.
Furnace slag
1.75
495,000
0
495,000
non-Missourl
Refinery slag
0.02
12,500
0
12,500
plants
Miscellaneous
slurries
0.05
2, 200
2,200
0
Industry total
699,200
49,100
650,100
(continued)
-------
TABLE II. (continued)
Metal
Category
Waste type
Waste generation
factor (tons/ton of product)t
1978 Solid
Total
generated^
waste generation statistics (tons)
Total potentially Total
hazardous' Nonhazardous'
Primary zinc,
Retort residue
1.14
137,000
0
137,000
pyrometal-
Ox ice furnace
lurgical
residue
0.37
44,400
44,400
0
Waelz kiln
residue
1.7
204,000
0
204,000
Acid plant
blowdown
0.042
44,600
4,600
0
Scrap brick
0.038
8,600
0
8,600
Cadmium plant
residue
0.002
200
200
0
Primary zinc.
Anode slimes
0.01
2,600
2,600
0
electrolytic
"Goethite"
residue
0. 36
15,100
0
15,100
Acid plant
blowdown
0.021
5,600
5,600
0
Dredge spoils
0.031
8,200
0
8,200
Wastewater treat-
ment sludge
0.038-0.09
8,700
0
8,700
Industry total
439,000
57,400
381,600
National total
4,735,850
721,650
4,014,200
* Quantities are in dry weight.
+ Waste generation factors represent average values,in most cases calculated from site specific data collected
during plant visits. Some generation factors are based on published values.
5 Total annual solid waste production quantities were calculated by applying waste generation factors to 1977
metal production data.
* The separation of solid wastes into hazardous and nonhazardous components is based on EPA's listing of hazardous
wastes in the December 18, 1978.Federal Register (43 Fed. Reg. 58946).
® Calspan Corporation. Assessment of industrial hazardous waste practices in the metal smelting and refining
industry. Solid Waste Management Series Publication SW-145 C. 2, Volumes 1 and 2. Environmental Protection Agency,
Solid Waste Management Division, Washington. 1977.
Note: Metric conversion table is given in front matter.
-------
reverberatory, Noranda, and flash smelting furnaces. (Electric
furnace slag is considered a hazardous waste.) The amount of
slag generated in 1978, excluding electric furnace slag, was
about 2.5 million tons (2.3 Tg). The other nonhazardous wastes
generated by the primary copper industry are miscellaneous
smelter and refinery slurries. The quantities of these wastes
are minor compared with slag.
The primary lead industry is the second largest producer of
solid waste in the nonferrous metals industry. In 1978 the lead
industry generated about 700,000 tons (635 Gg) of nonhazardous
waste and only 49,100 tons (44 Gg) of hazardous waste (Table II).
Furnace slag is by far the largest single source of solid waste
associated with the lead industry.
The primary aluminum and zinc industries each generate about
0.5 million ton (450 Gg) of solid waste annually. All the wastes
associated with the aluminum industry are currently considered as
nonhazardous. Most of the solid wastes from the primary zinc
industry are nonhazardous, consisting largely of residues from
the Waelz kiln and retort furnace. The remaining sources of
waste are small by comparison.
Solid waste quantities were projected to the years 1980,
1985, and 1990 (Table III) by use of the current solid waste
generation factors and projected metal production values for
those years. These projections do not reflect the potential
changes in the quantities of solid waste going to land disposal
in the future as a result of current and pending environmental
xxx
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TABLE III
PROJECTED SOLID WASTE FROM THE PRIMARY NONFERROUS
METALS INDUSTRY
(tons/year)
Industry
Waste type
1980
1985
1990
Aluminum
Potliners
Scrubber sludge
Scrap brick
Shotblast dusts
Casthouse dusts
202,300
141,500
135,700
31,200
13,700
276,500
139,300
199,900
31,200
18,700
329,400
139,300
245,600
38,400
22,300
Industry total
514,400
665,600
775,000
Copper
Slag
Acid plant
blowdown
Miscellaneous
slurries
Electrolytic refinery
slurries
3,271,500
12,000
27,000
3,600
4,587,500
14,500
32,500
4,300
4,976,000
16,500
35,500
4 ,700
Industry total
3,314,100
4,638,800
5,032,200
Lead
Slag
Miscellaneous
slurries
696,800
53,600
811,200
62,400
878,300
67,600
Industry total
750,400
873,600
945,900
Zinc
Anode slimes
"Goethite" residue
Acid plant blowdown
Dredge spoils
Waste water treatment
sludge
Retort residue
Oxide furnace residue
Waelz kiln residue
Scrap brick
Cadmium plant residue
3,100
15,100
11,000
9,500
8,700
137,000
44,400
204,000
8,600
200
3,600
15,100
12,200
11,300
8,700
137,000
44,400
204,000
8,600
200
4,300
15,100
13,600
13,200
8,700
137,000
44,400
204,000
8 ,600
200
Industry total
441,600
445,100
449,100
Note: Metric conversion table is given in front matter.
xxx i
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regulations. It is extremely difficult to make these estimates
because of uncertainties concerning future regulations,
standards, and compliance schedules, as well as the compliance
activities that industry might undertake.
No significant changes are predicted in wastes from the
primary aluminum, copper, or lead industries. The most
significant wastes currently generated by these industries are
expected to continue as the major waste sources. Although some
changes in quantities of waste going to land disposal are
expected to result from environmental regulations, the
proportions of these wastes will be small relative to total waste
generation.
The greatest change will probably be in the primary zinc
industry. If pyrometallurgical zinc plants are replaced by
electrolytic zinc facilities, which are cleaner and more
efficient, the generation of electrolytic sludges will increase.
Concurrently, though, the generation of pyrometallurgical zinc
wastes will decrease. The result will be an overall reduction of
waste going to land disposal because the more efficient
electrolytic plants generate substantially less waste per ton of
product.
Solid Waste Controls and Costs
In order to determine the potential cost impact of the RCRA
nonhazardous wastes Criteria, PEDCo conducted a detailed
evaluation of current and alternative solid waste control
practices and costs. The analysis includes all waste streams,
xxx ii
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whether hazardous or nonhazardous. The current control practices
cited are those most common in the nonferrous metals industry.
The alternative control practices represent improved handling and
disposal techniques that may eventually be required to satisfy
the RCRA Criteria and to ensure protection of human health and
the environment. Industry may also be required to implement
closure and postclosure operations to stabilize disposal sites
and to monitor and maintain them for 20 years after closure.
Costs of all current and alternative controls and of closure
and postclosure operations were calculated for each of the model
plants developed in this study. Costs of control at the model
plants were used to generate cost factors (dollars per ton of
metal product), which were then applied to total industry
production data to yield total industry costs.
Current Solid Waste Control Practices—Current control
practices are similar throughout the nonferrous metals industry.
Solids such as furnace slag from copper and lead plants, retort
and oxide furnace residue from zinc plants, and scrap potliners
and furnace brick from aluminum plants are typically placed on
the land in open dumps. Waste slurries from sources such as acid
plant blowdown, wet scrubbing waters, cooling waters, and plant
washdown are generally discharged to unlined lagoons or tailings
ponds, where they are neutralized and the solids allowed to
settle. At many plants the settled solids are dredged from the
lagoons and discarded on the land. At other plants the lagoons
are allowed to fill to capacity and new ones are constructed as
xxxiii
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needed. At still other plants the settled solids are dredged and
processed for their metal values.
Current control practices typically involve minimal effort
for selection and preparation of the disposal site. Site
selection is based mainly on convenience. Site preparation
consists mostly of clearing and grubbing the disposal area and
scooping out earth to form impoundments. Surface impoundments
generally are located and constructed to provide adequate control
of plant water and usually result in discharge from a single
point. Except at a few of the newer plants, current control
practice does not include the use of sealants or liners beneath
disposal areas. Likewise, few plants install or use wells to
monitor seepage or groundwater contamination. Systems of
drainage collection and diversion ditches have not been utilized
to their fullest potential for control of surface waters.
Costs of Current Solid Waste Controls—The total costs of
current solid waste controls are calculated on the basis of unit
costs, as described in Appendix C. They include both capital and
annual costs, in 1978 dollars. Capital costs include costs of
land, construction, and equipment. Construction costs for
current disposal practices include costs of land survey, minimal
site preparation (clearing and grubbing), construction of waste
haulage roads or rail systems, and construction of surface
impoundments. Land and construction costs are annualized over a
20-year period at 10 percent interest with no resale. Equipment
costs are annualized over a 10-year period at 10 percent interest
xxx iv
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with no resale. Annual costs include amortized capital costs and
costs of operation and maintenance, taxes, and insurance.
The estimated total costs of current controls in the primary
aluminum, copper, lead, and zinc industries are $9,214,700
capital cost and $4,722,650 annual cost (Table IV). On the basis
of annual production by each of these industries, the highest
annual cost of current controls is incurred in the lead industry
at $0.0007 per pound ($0.0015 per kg) of product; the lowest cost
is in the aluminum industry at $0.0002 per pound ($0.0004 per kg)
of product. The annual costs range from $3.60 per ton ($3.97 per
Mg) of solid waste for aluminum and $0.52 per ton ($0.57 per Mg)
for copper.
Alternative Solid Waste Control Practices—The alternative
solid waste control practices developed in this study are similar
to current practice but incorporate more effective and more
advanced means of planning, designing, constructing, maintaining,
and monitoring the disposal facilities. Process changes, such as
additional recycling and waste utilization, were not considered.
Important to this study, and reflected in the cost
estimates, are the assumptions that current waste disposal
facilities would be closed and not upgraded, and that new
disposal facilities would be opened within plant property lines.
The alternative controls, which provide what is assumed to
be adequate protection of human health and the environment, are
based on the RCRA nonhazardous waste Criteria, with consideration
of economic and technical feasibility. The alternative controls
xxxv
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TABLE IV
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR THE
PRIMARY NONFERROUS METALS INDUSTRY
(1978 dollars)
Industry
Total
capital
Total
annual
Total annual costs in:
($/lb of product) ($/ton of waste)
Aluminum
Copper
Lead
Zinc
National total
2,947,000
3,855,000
1,317,900
1,094,800
9,214,700
1,619,000
1,625,000
859,100
619,559
4,722,650
0.0002
0.0005
0.0007
0.0006
3.60
0.52
1.23
1.41
-------
include relatively intensive site selection, extensive site
preparation, lagoon lining and ground sealing, seepage collection
systems, runoff collection and diversion ditches, wells for
monitoring groundwater, flood protection dikes, access control
(fencing), closure of existing sites, and closure and postclosure
operation of alternative sites. Not all of these would
necessarily be required at any one facility; the need for
alternative controls eventually must be assessed by detailed
analysis of specific sites. Advanced methods of leachate
control, for example, would not be needed where the groundwater
is very deep or the native soils, geology, and topography provide
sufficient natural protection from groundwater contamination.
The alternative practices are not intended to be considered as
operational guidelines or standards that industry should be
required to follow; rather, they represent the level of control
that may be needed to satisfy RCRA Criteria and are used to
indicate the order of associated costs.
Although the alternative controls include all of the current
practices, any of them may require greater effort or more
extensive application than is now practiced. For example, site
preparation in current practice includes only clearing and
grubbing of the disposal area, whereas the alternative practice
specifies clearing and grubbing, removal of topsoil, and grading.
To date, little effort has been expended in site selection,
which is one of the most important aspects of the alternative
controls. It involves thorough assessment of such factors as
xxxvii
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drainage and runoff; proximity to natural waters, both surface
and underground; type, chemistry, and permeability of soils;
availability of land for site expansion; environmental
sensitivity of areas; aesthetics; and long-term land use. The
requirement for comprehensive site selection will increase the
immediate costs of disposal, but will minimize the long-term cost
and the adverse effects associated with indiscriminate selection
of disposal sites.
In the alternative controls, groundwater is monitored to
detect contamination from solid wastes. The specified system
incorporates six monitoring wells within the plant line.
Although the RCRA Criteria do not specifically require
closure of disposal sites, it is assumed that the alternative
sites would be closed after a 20-year service period to ensure
the continuing and long-term maintenance of environmental
integrity. Closure involves covering the solid waste with soil
and revegetating to prevent erosion. The soil cover consists of
a relatively impermeable bottom layer covered by an 18-in.
(45-cm) layer of soil that can support indigenous vegetation.
Monitoring and maintenance of the closed site are to be continued
for 20 years.
Costs of Alternative Solid Waste Controls—Costs of the
alternative controls are developed similarly to those for current
controls. Overall land requirements and the associated costs are
higher for the alternative controls because some of them require
additional land. Capital costs of the alternative controls
xxxviii
-------
include those for land, construction, and equipment as well as
for site selection, closure, and postclosure maintenance. Annual
costs include amortized capital costs, operation and maintenance
costs, taxes, and insurance.
The total estimated capital and annual costs to the industry
of implementing the alternative controls are $64,202,950 and
$14,254,060 (Table V).
Based on the total metal production by each industry, the
estimated annual cost of the alternative controls ranges from a
high of $0.0017 per lb ($0.0037 per kg) of lead produced to a low
of $0.0006 per lb ($0.0013 per kg) of aluminum. The highest
estimated annual cost based on total annual solid waste
generation occurs in the aluminum industry, at $12.03 per ton
($13.25 per Mg) of waste; the lowest cost occurs in the copper
industry at $1.70 per ton ($1.87 per Mg) of waste.
Closure of Existing Solid Waste Control Facilities—
Virtually all plants currently have onsite facilities for solid
waste disposal. The current and past control practices, however,
may not provide adequate protection of human health and the
environment according to RCRA standards; therefore, these sites
may be declared open dumps, in which case operators would be
required to close or upgrade them. For this study it is assumed
that all existing onsite disposal areas fail to meet RCRA
criteria, that these sites will be closed rather than upgraded,
and that new onsite disposal facilities that comply with RCRA
standards will be constructed.
xxx ix
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TABLE V
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR THE
PRIMARY NONFERROUS METALS INDUSTRY
(1978 dollars)
Industry
Total
capital
Total
annual
Total annual
($/lb of product)
costs in:
($/ton of waste)
Aluminum
24,881,000
5,576,000
0.0006
12.03
Copper
25,279,400
5,397,900
0.0012
1.70
Lead
8,259,700
2,038,800
0.0017
2.92
Zinc
4,782,850
1,241,360
0.0012
2.83
National total 64,202,950 14,254,060
-------
Closure of an existing facility is similar to closure
practices described earlier, i.e., a soil cover is placed over
the solid waste and is then revegetated to prevent erosion. The
closure costs do not include the cost of grading the waste or the
cost of postclosure monitoring and maintenance. The total
capital and annual costs to industry for closure of existing
solid waste disposal facilities are $14,711,700 and $1,748,700
(Table VI).
Analysis of Solid Waste Control Costs—The cost analysis
includes calculation of the total incremental cost of solid waste
control that would be incurred by the nonferrous metals industry
in implementing the alternative controls (Table VII). To allow
estimation of the potential cost impact of the RCRA nonhazardous
waste Criteria, the total incremental cost is apportioned to
hazardous and nonhazardous wastes. The total incremental annual
cost to the industry for control of nonhazardous wastes is
$9,657,350; this represents about 86 percent of the total
incremental annual cost of controlling both classes of wastes.
The fraction of the incremental cost of controlling
nonhazardous solid waste that can be attributed to the RCRA
Criteria is estimated by grouping the incremental costs into two
categories: state-standard-induced (cost of complying with
current state regulations) and Criteria-induced (cost of
complying with RCRA Criteria that are more stringent than state
standards). The Criteria-induced costs are those incremental
control costs that cannot be attributed to current state
xli
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TABLE VI
TOTAL COST OF CLOSING EXISTING SOLID WASTE DISPOSAL FACILITIES IN
THE PRIMARY NONFERROUS METALS INDUSTRY
(1978 dollars)
Industry
Total
capital
Total
annual
Total annual costs in:
($/lb of product)
Aluminum
Copper
Lead
Zinc
1,678,000
7,068,900
1,057,200
4,907,600
225,800
825,000
123,000
574,000
0.00002
0.0003
0.0001
0.0006
National total 14,711,700
1,748,700
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TABLE VII
CURRENT, ALTERNATIVE, CLOSURE, AND INCREMENTAL CONTROL COSTS FOR THE PRIMARY
NONFERROUS METALS INDUSTRY, BY WASTE TYPE
(1978 dollars)
Current Alternative* Closure5 Total Incremental1 Criteria-Induced^
Industry Haste type* Capital Annual Capital Annual Capital Annual Capital Annual Capital Annual
Aluminum
Nonhazardous
Hazardous
2,947,000
0
1,619,000
0
24,881,000
0
5,576,000
0
1,678,000
0
225,800
0
23,612,600
0
4,182,800
0
11,512,400
1,328,500
Total
2,947,000
1,£19.000
24,881,000
5,576,000
1,678,000
225,800
23,612,600
4 182,800
Copper
Nonhazardous
Hazardous
Total
2,996,500
858,500
3,855,000
1,269,500
255.500
1,6251000
22,349,400
3,930,000
26!279;400
4,448,900
949,000
5,3971900
5,313,900
1,755.000
7,068,900
621,000
204,000
825,000
24,666,800
4,826,500
29.493,300
3,800,400
797,500
4,597:900
12,490,900
1,634,100
Lead
Nonhazardous
Hazardous
Total
1,034,800
283,100
1,317,900
772.400
86,700
557HW
6,223,500
2,036,200
8:259:700,
1,614,600
424,150
2,038:800
962,100
95.100
1,0571200
112,600
11,100
123,700
6,171,900
1,827,100
7,999,000
957,200
346.200
1,303,400
3,068,800
420,500
Zinc
Nonhazardous
Hazardous
Total
376,900
716,900
1,094,800
276,350
343.200
1,907,850
2.875.000
4:782,650
507,000
734,360
1,241,360
4,156,600
751,000
4,9071600
486,300
87,900
574,200
5,687,550
2.908,100
B;595:650
716,950
479,060
1,196,010
5,118,500
575,400
National total
Nonhazardous
Hazardous
Total
7,335,200
1,859,500
3,937.250
785.400
4,722,650
55,361,750
8,841.200
64,202,950
12,146,500
2,107,510
14 254 060
12,110,600
2.601.100
14 711 700
1,445,700
303,000
1.748 700
60,138,850
9,561,700
W, 700,500
9,657,350
1,622,760
11,280,110
32,190,600
32,190,600
3,958,500
3,958,500
* Classification of solid waste as hazardous or nonhazardous 1s based on EPA's listing of hazardous waste in the December 18, 1978, Federal
Register (43 Fed. Reg. 58946). See Table II for types of hazardous and nonhazardous wastes for each Industry
+ Alternative control costs Include the cost of the alternative controls together with the cost of closing and maintaining the alternative
disposal sites.
* Closure costs represent the cost of closing existing solid waste disposal sites.
1 Incremental costs equal the sum of the cost of alternative controls and cost of closure minus the costs of current controls,
g
These values Include additional costs for closure of accumulated nonhazardous solid wastes, closure and postclosure maintenance of
alternative nonhazardous solid waste systens, and Criteria-Induced costs for states whose solid waste regulations do not satisfy the Criteria.
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regulations. Provisions of state regulations were determined by
consulting an analysis of state regulations and the proposed
Federal Criteria.
The major costs that are potentially attributable to the
RCRA Criteria are associated with four criteria, those dealing
with environmentally sensitive areas (floodplains), surface
water, groundwater, and safety (access). Costs entailed in
closure and postclosure maintenance of disposal facilities are
also attributed to RCRA; these costs cannot be directly
attributed to any one criterion but are indirectly attributable
to all. All closure costs are assumed to be attributable to the
Criteria because current state regulations do not include closure
and postclosure requirements. Other RCRA Criteria, those dealing
with wetlands, permafrost, critical habitat, sole-source
aquifers, air, disease vectors, explosive gases, fires, toxic
gases, and bird hazards, are considered inapplicable to the
nonferrous metals industry.
The Criteria-induced incremental annual cost for control of
nonhazardous wastes is $3,958,500; this represents 41 percent of
the total incremental annual cost for controlling nonhazardous
wastes.
Adding the current total annual cost of controlling
nonhazardous waste ($3,937,250) to the total incremental cost
(Criteria-induced and state-standard-induced) results in an
annual control cost for the aluminum, copper, lead, and zinc
industries of $13,594,600. This represents a 3.5-fold increase
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in disposal costs, with 59 percent of the increase due to state
regulations (state-standard-induced costs) and the remaining 41
percent attributable to the Criteria (Criteria-induced costs).
The major factors contributing to the Criteria-induced costs
are closure of disposal facilities and postclosure operations,
both of which are assumed will be required at all facilities to
satisfy the Criteria. The specific RCRA Criteria of concern in
this study (those dealing with floodplains, surface water,
groundwater, and safety) contribute little to the
Criteria-induced costs because most state regulations concerning
these categories are at least as stringent as the Federal
Criteria and some are more stringent.
Table VIII presents a summary of current, incremental, and
Criteria-induced costs for control of nonhazardous wastes. The
highest total incremental cost in dollars per ton of waste occurs
in the aluminum industry ($9.27 per ton or $10.22 per Mg). The
portion of this cost that can be attributed to the Criteria is
only $2.95 per ton ($3.25 per Mg), or 32 percent of the total
incremental cost. The total incremental costs to the other
industries are lower than that calculated for the aluminum
industry. The portions of the incremental costs that can be
attributed to the Criteria in the copper, lead, and zinc
industries are 43, 44, and 80 percent respectively.
The potential economic impact on the nonferrous metals
industry that is attributable to RCRA, either the total
incremental cost or the smaller Criteria-induced cost, appears to
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TABLE VIII
ANNUAL CURRENT, INCREMENTAL, AND CRITERIA-INDUCED COSTS FOR CONTROL OF NONHAZARDOUS
WASTES FROM THE PRIMARY ALUMINUM, COPPER, LEAD, AND ZINC INDUSTRIES
(1978 dollars)
Current costs in*
Incremental costs in:
Criteria-induced costs in:
Industry
<
H-
Aluminum
Copper
Lead
Zinc
(S/lb of product) ($/ton of waste) (S/lb of product) ($/ton of waste) (S/lb of product) ($/ton of waste)
0.0002
0.0004
0.0006
0.0003
3.60
0.51
1.19
0.65
0.92
0.001
0.0008
0.0007
9. 27
1.50
1.47
1.88
0.0001
0.0005
0.0003
0.0006
2.95
0.65
0.65
1.51
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be small. Capital costs are significant for some of the
industries, but not unmanageable. Annual costs, including
annualized capital costs, are quite low, and it appears that they
could be shifted forward into product price without significant
loss of market.
Minor Primary and Secondary Nonferrous Smelting and Refining
Industries
The minor primary and secondary nonferrous metals industries
that produce significant quantities of solid wastes include the
smelting and refining of primary tin, antimony, mercury, and
titanium and the smelting and refining of secondary copper, lead,
and aluminum. Secondary zinc smelting is not considered in this
group because it generates very little land-disposed waste.
The remaining primary industries are small in comparison to
those described above. Many of these industries (cadmium,
arsenic, selenium and tellurium, gold and silver, platinum, and
bismuth) process the residuals, slimes, dusts, and sludges from
the primary copper, zinc, or lead industries to recover the minor
metals.
Secondary metals include all metals and metal alloys
recovered from scrap and waste. The final products are produced
to specifications for individual applications and their quality
parallels that of comparable-grade materials made by primary
producers.
The only secondary smelting and refining industries of
appreciable production capacity are the secondary copper, lead,
zinc, and aluminum industries. Annual production from these
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industries ranges from approximately 384,000 tons (348 Gg) of
secondary copper to approximately 1,430,000 tons (1.30 Tg) of
secondary aluminum. Whereas the larger primary industries
consist of a relatively small number of high-capacity plants
located in sparsely populated areas near the mine-mill complexes,
the secondary nonferrous metals industry consists of relatively
large numbers of plants located in urban areas where the scrap
raw material is readily available. Total waste quantities from
the 2,600,000 tons (2.3 Tg) (Table IX) of metal produced in these
industries in 1977 are estimated to be 1,157,200 tons (1.05 Tg)
per year, with 524,000 tons (475 Gg) or 49.6 percent of this
total considered nonhazardous.
This analysis does not include determining alternative
control measures for individual minor primary and secondary
nonferrous smelting and refining industries. The control
practices described in detail earlier for primary copper, lead,
zinc, and aluminum, however, would also be applicable to these
industries, and the need for any or all of the alternative
controls would be assessed by evaluation of specific sites.
On the basis of control costs per unit of solid waste
generated in the major primary industries, it is roughly
estimated that the total incremental costs of controlling
nonhazardous solid wastes generated by the seven minor primary
and secondary smelting industries discussed above would be
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TABLE IX
ANNUAL METAL PRODUCTION AND SOLID WASTE GENERATION BY MINOR
PRIMARY AND SECONDARY NONFERROUS METALS INDUSTRIES
SoUd waste generated1' (tons/year)
Number
Production
Potentially hazardous^
Nonhazardous5
Industry
of plants*
(tons/year)*
Total
Total
Component
Quantity
Total
Component
Quantity
Primary tin
1
7,370
6,820
6,820
Smelting slag
6,820
Primary antimony
2
4,070
11,700
11,700
Blast furnace slag
Electrolytic sludge
11,450
250
Primary mercury
1
1,060
220,000
220,000
Kiln/retort
residue
220,000
Primary titanium
3
16,500?
5,600
5,600
Chlor1nat1on sludge
5,600
Secondary copper
46$
384,000
196,000
196,000
Blast furnace slag
Electrolytic waste
water sludge
195,920
80
Secondary lead
12(*
756,000
192,000
3,000
Scrubber sludge
3,000
189,000
Blast, cupola and
reverb, furnace slag
189,000
Secondary aluminum
JOQg
1.430.000
525,000
372,000
High salt slag
372,000
153,000
Scrubber sludge
153,000
Total
273
2,599,000
1,157,130
582,700
574,420
* U.S. Bureau of Mines. Minerals yearbook, 1975 ed., Washington, U.S. Government Printing Office, 1975, except as noted.
U.S. Bureau of Mines. Mineral conmodlty sunmarles 1979. Washington, U.S. Department of the Interior, 1979, except as noted,
t Based on Maste generation factors from Table 6-1.
§ Separation of the solid Maste Into hazardous and nonhazardous components Is based on EPA's listing of hazardous wastes In
the December 18, 1978, Federal Register (43 Fed. Reg. 58946).
1 Based on total U.S. production capacity Actual production data withheld to protect company confidential data.
P Personal communication. Selected personnel of the Division of Ferrous Metals, U.S. Bureau of Mines, Washington, D.C., to
R.S. Amick, PEDCo Environmental, Inc., February 1979.
Note Metric conversion table is given In front matter.
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$16 million* in capital cost and $2.6 milliont annually. As with
the major primary industries, only a portion of the total
incremental cost can be attributed to the RCRA nonhazardous waste
Criteria because many of the current state regulations include
requirements as stringent as the Federal Criteria or more so.
* Based on $30 per ton of solid waste ($33 per Mg).
t Based on $5 per ton of solid waste ($5.50 per Mg).
1
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SECTION 1
INTRODUCTION
The ultimate disposal of industrial solid wastes on the land
in an environmentally sound manner is a rapidly increasing
problem. The adverse environmental and economic impacts of
disposal facilities that are improperly located, designed,
operated, monitored, and controlled are sure to increase
nationwide, becoming severe at local and regional levels. The
severity of problems associated with industrial solid waste
disposal results from several factors. First, more wastes are
being disposed of on the land in response to population
increases, economic growth, and affluence. In addition,
legislative mandates are leading to increased production of solid
wastes by requiring the reduction or elimination of air and water
pollutants.
Second, many new solid wastes, some of them exotic and many
of them toxic, are being produced through chemical research and
production of new materials.
Third, these wastes tend to be concentrated in relatively
large disposal facilities that generate large amounts of
leachate.
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Fourth, the solid waste disposal facilities in the United
States are generally uncontrolled, even those accepting hazardous
wastes. Control is lacking especially for protection of
groundwaters: solid waste disposal sites are seldom monitored,
dumping is often indiscriminant, and there is no effective
Federal legislation for protection of groundwaters from solid
waste leachate.
Fifth, considerable time must pass before a disposal site
reaches field capacity and produces leachate; also, the
production of leachate and the movement of groundwaters, are
slow. Therefore, the impacts of land disposal sites may not be
realized until years after the wastes are deposited, and their
duration may be long.
The effort to abate these problems of industrial solid waste
disposal requires background information to identify and define
the specific solid waste problems of various industries. This
report deals with solid waste generation and management at
domestic nonferrous metal smelters and refineries. The study is
one of a series of investigations of industrial solid wastes
conducted for the EPA Office of Solid Waste (OSW) to provide
support for implementation of P.L. 94-580, the Resource
Conservation and Recovery Act of 1976 (RCRA). These studies are
being conducted for informational purposes only and not in
response to congressional mandate.
The Resource Conservation and Recovery Act of 1976 is an
amendment to a prior statute, the Solid Waste Disposal Act of
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1965. The main purpose of the act is to ensure that solid wastes
are managed so as to prevent damage to public health and the
environment. The objectives of the Act are:
° Regulation of hazardous wastes from the point of
generation through disposal,
° Improvement of disposal practices for nonhazardous
wastes to meet environmental and health standards, and
° Promotion of resource recovery and conservation as the
preferred methods of waste management.
To realize the objectives of RCRA, EPA must first develop
the basic regulatory standards and guidelines called for in the
Act. The focus will then fall upon state and local governments,
which must apply the standards with Federal- support in the form
of financial and technical assistance.
EPA is currently promulgating regulations under Subtitle C
(Hazardous Waste>Management) and Subtitle D (State or Regional
Solid Waste Plans) of RCRA. Subtitle C addresses only hazardous
wastes, and Subtitle D addresses all other wastes (nonhazardous
wastes). This study is concerned with regulations to be
promulgated under Subtitle D. Although Subtitle D applies to
nonhazardous wastes only, and the main emphasis in this report is
on nonhazardous wastes, the report addresses all solid wastes
associated with nonferrous metal smelters and refineries,
including hazardous wastes, for the following reasons: (1) the
regulations defining what constitutes hazardous and nonhazardous
wastes are only proposed at this time and may be changed; (2) the
distinction between hazardous and nonhazardous wastes is often
1-3
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difficult because some operations combine hazardous and
nonhazardous wastes in a common disposal area; (3) inclusion of
both hazardous and nonhazardous solid wastes provides a
comprehensive picture of the solid waste management problems and
practices at nonferrous metals operations and places the problems
in proper perspective. In this study the distinction between
hazardous'and nonhazardous wastes is based on information in the
December 18, 1978 Federal Register (43 Fed. Reg. 58946), which
identifies specific types of hazardous wastes by industry. All
solid wastes not specifically identified in the Federal Register
are considered nonhazardous.
Section 1008(a)(3) under Subtitle D of RCRA requires that
EPA provide criteria to be used by the states to define solid
waste management practices that constitute the open dumping of
solid wastes. Section 4004(a) of RCRA requires that EPA
promulgate regulations containing criteria for determining which
solid waste disposal facilities pose "no reasonable probability
of adverse effects on health or the environment from disposal of
solid waste at such facility," and which facilities do pose such
a probability.* The Criteria are intended to provide minimum
national standards for protection of health and the environment
from the disposal of nonhazardous wastes.
* In the February 6, 1978 Federal Register (43 Fed. Reg.
4942), EPA proposed "Criteria for the Classification of Solid
Waste Disposal Facilities" (40 CFR Part 257). These proposed
regulations are referred to in this report as "the Criteria."
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In developing the Criteria, EPA recognizes many factors must
be considered in determining whether solid waste disposal
operations will generate adverse impacts and what the magnitude
of these impacts will be. EPA also must consider the possible
impacts of the proposed Criteria on an industry producing large
volumes of nonhazardous waste. For these reasons EPA has
commissioned this study of solid waste disposal in the nonferrous
metals industry. The report resulting from this study provides:
(1) a data base on the type and quantity of wastes generated and
the treatment and disposal techniques now applied for their
control; (2) a basis for planning of technical assistance
activities; and (3) the background information needed to develop
a long-term strategy for Federal policies concerning solid wastes
from nonferrous metal smelters and refineries. This report also
provides information concerning the costs to industry of meeting
the RCRA 4004 Criteria. The Criteria-induced costs are the
additional costs above current solid waste disposal costs that
are incurred in bringing existing facilities into compliance with
the Criteria.
EPA has no regulatory authority under Subtitle D with regard
to nonhazardous wastes. It is expected, however, that most
states will adopt the 4004 Criteria as their minimum standards
and thus that implementation of the Criteria will be through the
state agencies. EPA will encourage states to implement the
Criteria for industrial waste disposal sites but will emphasize
1-5
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economic incentives to encourage industries to adopt voluntary
alternative practices for waste reduction and disposal where such
alternatives are appropriate.
This study covers the smelting and refining portions of
nonferrous metals industry; that is, those operations that
process concentrated ores from the mining and beneficiating
segments of this industry. The most important nonferrous metals
industries in terms of number of operations and quantity of
material handled are the primary aluminum, copper, lead, and zinc
industries. The minor primary metals industries (e.g. antimony,
beryllium, titanium) and the secondary metals industry are less
important from the standpoint of size, geographic distribution,
quantity of wastes generated, and environmental impacts. For
these reasons, the primary aluminum, copper, lead and zinc
industries are emphasized.
A brief assessment of the primary minor and secondary
nonferrous metals industries conducted for the study consisted of
identifying the sources and quantities of solid wastes associated
with these industries. Radioactive metals, metals produced by
chemical manufacturers (e.g. magnesium and sodium), and metals
produced only for research purposes are excluded from this
analysis. Further, the analysis covers only the smelting portion
of the primary aluminum industry because the refining segment is
addressed in another industrial solid waste project being
conducted for EPA.
1-6
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Many of the operations associated with production of
nonferrous metals generate solid wastes. Some of the wastes
include, for example, inorganic slags from smelters, electrolytic
slimes, sludges from electrolytic regeneration and purification,
fumes and particulate matter captured in air pollution control
equipment, acid plant blowdown, worn-out mechanical trash, and
water treatment sludges. Large quantities of residuals generated
at some nonferrous metals operations have been addressed as solid
wastes in other studies; those, however, are not wastes according
to the RCRA definition because they are eventually recycled or
processed for recovery of metal values. These residuals include
some particulates or dust collected by air pollution control
devices, some acid plant blowdown, and some miscellaneous
slurries and sludges. Such materials do constitute a waste at
some operations, but by far the vast majority are recycled for
metal recovery immediately or after short periods of storage.
The approach to this study was to acquire, compile, and
analyze as much available information as possible concerning the
generation, control, regulation, and environmental effects of
solid wastes from the nonferrous metals industry; this
information was used to generate a data-base report that formed
the basis for the full technical study and report.
Data gathering consisted of four major tasks, each concerned
with a particular information source. The first task was a
literature search for published and unpublished information. It
1-7
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involved conducting several computerized searches (e.g., NTIS,
MEDLINE, TOXINE) and contacting public, academic, and
governmental libraries.
The second task was to contact governmental agencies whose
realm of responsibility includes the metallurgical industry
and/or effects of the industry. The contacts were initiated
through letters and telephone conversations. Information was
obtained in the form of documentation (published and unpublished)
and personal communications. Appendix A lists the agencies and
personnel contacted.
The third task was to contact trade associates that could
provide industry contacts, furnish answers to general and
specific questions, and help arrange visits to industrial sites.
The following trade associations were contacted:
American Mining Congress (AMC), Washington
° Jim Walpole, Legal Counsel
Arizona Mining Association (AMA), Phoenix
° E. J. Johnson
Northwest Mining Association (NWMA), Spokane
° Carl Mote, Executive Director
Colorado Mining Association, Denver
° Dave Cole, Executive Director
Aluminum Association
° Seymour G. Epstein
The final data-gathering task was to visit smelters and
refineries to obtain specific data on operations and solid wastes
and to solicit comment from industry personnel regarding the
issues of this project. (The trade associations arranged most of
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the visits.) The following operations (listed by industry) were
visited:
Aluminum
National-Southwire Aluminum Co., Hawesville, Kentucky
Copper
ASARCO, Inc., El Paso, Texas
Kennecott Copper Corp., Hurley, New Mexico
Magma Copper Co., San Manuel, Arizona
Lead
AMAX, Inc., Boss, Missouri
ASARCO, Inc., El Paso, Texas
ASARCO, Inc., Glover, Missouri
St. Joe Minerals Corp., Herculaneum, Missouri
Zinc
AMAX, Inc., East St. Louis, Illinois
ASARCO, Inc., Corpus Christi, Texas
National Zinc Co., Bartlesville, Oklahoma
New Jersey Zinc Co., Palmerton, Pennsylvania
The main body of the report covers five major topics.
Sections 2 through 5 give a detailed evaluation of the solid
waste management practices and problems associated with the four
nonferrous metal industries emphasized in this study: primary
aluminum (Section 2); primary copper (Section 3); primary lead
(Section 4); and primary zinc (Section 5). Each discussion is
organized into three subsections:
Industry Characterization
Solid Waste Characterization
Solid Waste Control Practices and Costs
The industry characterizations characterizes each of the
metal categories according to the following: raw materials,
production/capacity (includes product prices), companies
(includes number of firms and plants, location, and employment),
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energy consumption, and outlook (economic and technological). In
addition, the industry characterization provides flow diagrams
and descriptions of the smelting and refining processes currently
used within each industry.
The solid waste characterizations of the primary aluminum,
copper, lead, and zinc industries are based on model plants
developed to be representative of these industries. The array of
model plants developed for each industry is as follows: three
models for aluminum (one each for plants with wet scrubbing,
plants with dry scrubbing, and plants with both wet and dry
scrubbing); five models for copper (one each for reverberatory
smelting, electric smelting, flash smelting, Noranda smelting,
and electrolytic refining); two models for lead (one each for
Missouri and non-Missouri smelting and refining operations); two
models for zinc (one each for pyrometallurgical and electrolytic
operations).
Solid waste quantities are calculated and presented as waste
generation factors according to individual process steps for each
model. The generation factors are given for each type of waste
in tons per ton of metal product produced. These factors,
calculated from data obtained during site visits and values
reported in the literature, are used to estimate total annual
solid waste production by all plants represented by a model.
Solid waste statistics are presented for each metal category by
state, by EPA region, and by national totals. These statistics
do not include those residuals from air and water pollution
1-10
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control devices which are being either directly recycled to the
process or sent elsewhere for metal recovery after temporary
on-site storage.
The section on solid waste control practices and costs
describes practices for control of all wastes (hazardous and
nonhazardous) and their associated costs. Both current and
alternative control practices are considered. The current
control practices represent those used most commonly by industry.
The alternative practices represent improved methods of solid
waste handling and disposal that may be required under RCRA to
ensure adequate protection of human health and the environment.
The alternative control systems specified in this study are based
on contractor investigations and professional judgment. The RCRA
nonhazardous waste criteria were used as guidelines in developing
the alternatives, with consideration for both technical and
economic feasibility. The alternatives are not intended to be
considered as operational guidelines or standards that industry
should be required to follow, but rather they represent the level
of control that would be expected to satisfy RCRA criteria.
The solid waste control costs are calculated according to
the model plants associated with the four major industries
addressed in this study. The model plant cost factors are
presented in dollars per ton of metal product. The cost factors
are used to calculate the capital and annual costs of both
current and alternative solid waste control systems. All costs
are presented in 1978 dollars.
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The final portion of the controls and control costs section
for each major industry consists of a cost analysis. Costs of
current and alternative controls for the total industry are
compared to determine the additional industry cost incurred to
meet RCRA criteria, both for hazardous and nonhazardous wastes.
The incremental control costs associated with nonhazardous wastes
are presented on a state-by-state basis to determine the
proportions of increased costs that are attributable to state
solid waste regulations (state-induced costs) and to the
nonhazardous waste section (Section 4004) or RCRA
(Criteria-induced costs).
Following a detailed evaluation of each of the four major
industries (primary aluminum, copper, lead and zinc) is an
assessment of the primary, minor (e.g., antimony, beryllium,
titanium) and secondary nonferrous metals industry segments
(Section 6). The assessment consists of an identification of
sources, quantities, and characteristics of solid wastes
associated with these industries. This assessment is based
entirely on a literature review. The primary output of this
assessment is identification of those industries that should be
of concern to EPA because of the volume of waste that they
generate or the nature of the waste.
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The text of this report gives English units of measure,
followed by metric units according to usage of the International
System of Units (SI) (Mechthy 1969) in parentheses. Tables and
figures give English units only; the reader is referred to a
metric conversion table in the front matter, which also sites the
basic SI units and SI prefixes.
1-13
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SECTION 2
ALUMINUM INDUSTRY
Industry Characterization
Technologies for large-scale production of aluminum were
developed late in the 19th century, and it is now used in
virtually all segments of the economy. Although the explosive
growth that began during World War II has largely subsided,
continuing growth of the aluminum industry is likely. The
primary aluminum industry is composed of three distinct segments:
the mining and beneficiating of bauxite ores, the refining of
bauxite to produce alumina, and the reduction of alumina to
aluminum metal. Unlike the processing of most other metals, all
purification takes place during refining rather than during the
reduction to metal. Aluminum smelting (reduction to metal)
includes electrolysis to reduce the metal, casting, paste
preparation, and sometimes anode preparation.
The primary aluminum industry faces several major problems.
First, the U.S. bauxite reserves are inadequate to meet domestic
needs. As a result, domestic aluminum smelters depend heavily on
imported bauxite and alumina, and the producing countries have
raised prices rapidly in recent years. In addition, because
domestic smelter capacity is inadequate to meet expected demand
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in the near future, the imports of aluminum metal must increase.
Another major problem facing the industry is the shortage of
low-cost energy. Aluminum production requires considerable
amounts of both electrical and thermal energy, and although most
facilities have been located to take advantage of inexpensive
sources of fossil fuels, the rapidly increasing cost and
potential shortage of these fuels could significantly affect the
ability of the industry to produce a competitively priced
product. Pollution control presents further problems for this
relatively young industry. Unfortunately, conventional
production technologies release fluorides, organics, sulfur
dioxide, and some heavy metals to the environment, and effective
control can be complicated and expensive.
Worldwide, almost all bauxite mined is refined by the Bayer
process, patented in Germany in 1888. This process involves
leaching with caustic at high temperature and pressure, followed
by separation of the solution and precipitation of alumina.
There are two principal variations of the Bayer process. The
European Bayer process, used for monohydrate ores, requires
higher temperatures, and pressures, greater caustic
concentrations, and longer digestion times than the American
Bayer modification, which is applicable to trihydrate ores. A
variation of the American Bayer process includes a step to
reclaim additional alumina from high-silica bauxites. Aluminum
metal is produced from calcined alumina by electrolysis in a
molten bath of cryolite. Three types of electrolytic cells are
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in use: prebake, horizontal stud Soderberg (HSS), and vertical
stud Soderberg (VSS). The differences are largely in anode
configuration and method of alumina addition.
Industry Description
Raw Materials—Aluminum is the most abundant metallic
element in the earth's crust, although it is never found free in
nature. The principal aluminum ore is bauxite, a mixture of
hydrated aluminum oxides. The principal minerals in bauxite are
gibbsite, a trihydrate, and the monohydrates boehmite and
diaspore. Common impurities are quartz, kaolinite clay, and iron
oxides; essentially no sulfur or potentially hazardous trace
elements are present. Bauxite ores range from stony materials to
soft claylike masses.
Most bauxite reserves are located in tropical regions, far
from industrialized areas of potential consumption. World
reserves are estimated at 24.2 billion tons (22 Pg), one-third of
which is located in Guinea (2-1). Jamaica is the world's largest
bauxite producer, followed in order by Guinea, the U.S.S.R.,
Surinam, Guyana, Greece, Hungary, and the United States (2-2).
In 1974 eleven of the major bauxite exporting countries formed
the International Bauxite Association in order to increase
revenues and control operations in member countries. The levies
imposed on bauxite by the producing countries are now the largest
element of its cost (2-1).
In 1977 total domestic mine production of bauxite was
approximately 2.22 million tons (2.01 Tg) (2-3); about 7 percent
2-3
-------
of this bauxite was used in production of abrasives,
refractories, and chemicals rather than for aluminum metal. Only
about 8 percent of aluminum produced in this country is from
domestic mines (2-1,2-4).
Consumption of bauxite in the United States outsteps mine
production; domestic reserves of 39.6 million tons (35.9 Tg) are
inadequate to meet long-term demand (2-1). The domestic aluminum
refineries now rely heavily on imports of bauxite, especially
from the Caribbean area, northeastern South America, and western
Africa. Of the nine U.S. bauxite refineries, seven process only
imported ore (2-1). The trend, however, is toward increased
imports of alumina, a purified aluminum oxide, rather than
bauxite. About a third of the alumina used in the U.S. aluminum
smelters is imported, primarily from Australia.
Large nonbauxitic sources of alumina in the United States
could meet domestic aluminum demand indefinitely; however, the
costs associated with extracting and processing these raw
materials is higher than costs of using bauxite (2-1). The
Bureau of Mines is examining new technology for producing alumina
from nonbauxite sources. Although development of this technology
will not affect the output of solid waste from smelters, it will
dramatically reduce our dependence on imported alumina.
Among the raw materials other than bauxite that are used for
production of aluminum are cryolite (Na0AlF,), fluorspar (CaF„),
Jo ^
and sodium and aluminum florides, which are added prior to
electrolysis. Various inorganic salts, chlorine, and inert gases
2-4
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are used to remove impurities during casting. In addition to
these materials, caustic, lime, coke, and pitch are used at
various points in the smelting process.
Production and Capacity—The principal product of the
industry is aluminum metal. Gallium is recovered at one location
as a byproduct of the refining of domestic bauxite. Some bauxite
deposits contain appreciable amounts of titanium, but no
economical methods of extraction have been developed (2-5).
Although aluminum metal is soft, its alloys have high
strength relative to weight. The principal applications take
advantage of this weight saving and of the tendency of aluminum
to form an oxide surface that resists corrosion. Aluminum is the
most widely used nonferrous metal. The principal markets are for
building and construction, transportation equipment, and
containers and packaging. Packaging and transportation are the
fastest-growing markets, but use of aluminum is increasing in
many segments of the economy. Copper, magnesium, titanium, and
steel can be substituted in many aluminum applications, but often
at higher costs or significant weight penalties. The most
promising substitutes are steel and wood in construction, and
steel, plastic, glass, and paper in containers.
Primary domestic aluminum production in 1977 was 4,539,000
tons (4.1 Tg), with a value of $4.6 billion (2-6). Table 2-1
summarizes the general 1977 statistics of the industry, with
projections to the year 2000. Based on these estimates, the
annual growth rates for primary aluminum production would be 6.44
2-5
-------
TABLE 2-1
U.S. PRIMARY ALUMINUM INDUSTRY STATISTICS*
(tons except as noted)
Production
1977 4,539,000
1980 5,474,000
1985+ 7,480,000
1990 8,910,000
1995 10,613,000
2000+ 12,640,000
Imports
Crude and semicrude 836,000
Consumption
Apparent 5,439,000
Exports
Crude and semicrude 411,000
Average U.S. producer price
Ingot ($/lb average) 0.52
Total value of annual production (millions $) 4,600
* Mineral industry survey. Aluminum industry in 1977.
U.S. Department of the Interior, Bureau of Mines, Washington
D.C. March 1978. All values are 1977 statistics unless
otherwise noted.
^ Personal communication, J.W. Stamper, Bureau of
Mines to D. Sass, PEDCo. November 1978.
Note: Metric conversion table is given in front matter.
2-6
-------
percent between 1977 and 1985 and 3.56 percent between 1985 and
2000. With these factors production estimates can be made for
1980, 1990, and 1995, as given in Table 2-1. Although over
one-fourth of the aluminum industry's capacity was closed during
1975, production has rebounded from this 5-year low, averaging
91.9 percent of capacity in 1977 (2-7,2-8). Nevertheless, the
United States will likely become increasingly dependent on
imports of aluminum metal unless domestic smelting capacity is
increased sharply.
The price of aluminum was stable in the years from 1950 to
1968, ranging from $0.25 to $0.32 cents per pound (in 1968
dollars) (2-9). This stability resulted from the high degree of
integration in the industry, improvements in processing, and the
long-term price stability of electric power. In recent years,
however, prices have climbed rapidly; the average price per pound
of ingot in 1977 was $0.52, up from $0,253 in 1973 (2-6).
Companies—Nearly half of the total world production
capacity for bauxite, alumina, and aluminum is controlled by six
corporate groups or their subsidiaries: Alcan Aluminum (Canada),
Aluminum Company of America (Alcoa), Reynolds Metal, Kaiser
Auminum and Chemical, Pechiney and Ugine (France), and Swiss
Aluminum (2-7). All of these groups are fully integrated from
bauxite mining through fabrication. Of the three large American
concerns, only Kaiser has significant interests in operations
other than aluminum. Twelve companies produce primary aluminum
in the United States; five of these also produce alumina
2-7
-------
domestically. Alcoa was the only domestic producer until World
War II. Smaller producers are generally more limited in scope,
although most own fabricating plants in addition to bauxite
refineries or other primary production facilities. The industry
has been characterized by aggressive marketing.
Table 2-2 lists the primary aluminum smelters in the United
States, with related information. Annual production capacity of
the plants, which operate around the clock throughout the year,
ranges up to 280,000 tons of aluminum (254 Gg). Much larger
smelters are feasible; a Canadian plant can produce 454,000 tons
(412 Gg) per year and one Russian facility can produce 550,000
tons (500 Gg) per year (2-8). The industry is relatively young;
only three plants predate the rapid expansion of the industry
during World War II. A second major expansion occurred during
the 1950's, and eight additional plants have started within the
last decade. The older smelters are electrochemically equivalent
to the newer, although process modifications have increased
production efficiency and reduced polluting discharges (2-10).
Nine of the eleven plants opened since 1960 use prebake anodes,
and one is testing a chloride bath process. Recent plant
expansions support the trend toward prebake anodes: 99 percent
of the total 60,000 tons (324 Gg) added to existing smelter
capacity since 1973 has been at prebake facilities (2-8). Of the
industry's total annual capacity of 5.3 million tons (4.8 Tg), 73
percent is attributable to prebake plants, 19 percent to HSS
plants, and 8 percent to VSS plants (2-11). All the plants using
2-8
-------
TABLE 2-2
U.S. PRIMARY ALUMINUM PRODUCERS*
Company/location
Capacity
(tons/year)
Cell
type"1
Startup
date
Aluminum Company of America
Evansville, Ind.
Massena, N.Y.
Badin, N.C.
Alcoa, Tenn.
Rockdale, Tex.
Palestine, Tex.
Vancouver, Wash.
Wenatchee, Wash.
Anaconda Aluminum Co.
Sebree, Ky.
Columbia Falls, Mont.
Conalco, Inc. (owned by
Swiss Aluminum and Phelps Dodge)
Lake Charles, La.
New Johnsonville, Tenn.
Eastalco Aluminum Co.
(sub. of Howmet§)
Frederick, Md.
Intalco Aluminum Corp.
(owned by Alumax and Howmet§)
Ferndale, Wash.
Kaiser Aluminum & Chemical Corp.
Chalmette, La.
Ravenswood, W. Va.
280,000
230,500
179,500
227,000
285,500
30,000
114,500
189,500
120,000
179,500
36,500
144,500
176,500
260,000
260,000
163,000
PB
PB
PB
PB
PB
PB
PB
PB
VSS
PB
PB
PB
PB
HSS
PB
1960
1903
1916
1914
1952
1976
1940
1952
1974
1955
1974
1963
1970
1966
1951
1957
(continued)
2-9
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TABLE 2-2 (continued)
Company/location
Capacity
(tons/year)
Cell
type +
Startup
date
Mead, Wash.
220,500
PB
1942
Tacoma, Wash.
80,500
HSS
1942
Martin Marietta Aluminum, Inc.
The Dalles, Oreg.
90,500
VSS
1958
Goldendale, Wash.
120,000
VSS
1972
National-Southwire Aluminum Co.
Hawesville, Ky.
200,000T
PB
1969
Noranda Aluminum, Inc.
New Madrid, Mo.
140,000
PB
1971
Ormet Corp.
(owned by Conalco and Revere)
Hannibal, Ohio
260,000
PB
1958
Revere Copper & Brass, Inc.
Scottsboro, Ala.
113,500
PB
1971
Reynolds Metal Co.
Listerhill, Ala.
202,000
HSS
1940
Arkadelphia, Ark.
68,500
HSS
1954
Jones Mills, Ark.
124,500
PB
1942
Massena, N.Y.
125,500
HSS
1953
Troutdale, Oreg.
130,000
PB
1952
Longview, Wash.
209,500
HSS
1941
* Primary Aluminum Plants, Worldwide. Part One, U.S. Dept. of Interior, Bureau
of Mines, Denver, Co. Aug. 1977.
PB—prebake; HSS—Horizontal-stud Soderberg; VSS—vertical-stud Soderberg.
§
Hornet Corporation is owned 69 percent by Pechiney Agine Kuhlmann.
Capacity updated by plant visit information.
Note: Metric conversion table is given in front matter.
2-10
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HSS anodes are currently being modified with Japanese reduction
technology. Primary smelters employed about 23,000 to 26,000
workers in 1978 (2-7).
Two new primary smelters scheduled for early completion are
owned by Alumax, a joint venture of Amax, Mitsui and Company, and
Nippon Steel. One will be located in Umatillo, Oregon, and the
other in Berkley County, South Carolina, 20 miles north of
Charleston; both will use prebake anodes. Plans for the South
Carolina plant include a requirement for zero wastewater
discharge, and cost of pollution control equipment will amount to
one-eighth of the total capital expenditure. Three prebake
plants are undergoing expansion programs that will further
increase the annual capacity of the industry by 65,000 tons (60
Gg) (2-8). Despite this new capacity and expansion, growth in
demand is expected to exceed production capacity for the next 5
to 6 years. This could significantly affect the competitive
impact of any price increases caused by stringent pollution
control requirements. Fifteen percent of the smelter capacity of
U.S. concerns is located abroad, and this trend is likely to
continue (2-12).
Energy Consumption—In 1971 the only industries that
consumed more energy than the aluminum industry were blast
furnaces and steel mills, petroleum refining, and the manufacture
of paper and allied products, olefins, and ammonia (2-12). The
aluminum reduction process accounts for 0.8 percent of all energy
consumed by manufacturing industries in the United States (2-13).
2-11
-------
In 1975 the annual energy consumption of the primary aluminum
industry was estimated at 1,408 trillion Btu (1.49 EJ) (2-14).
The energy required to produce 1 net ton (0.9 Mg) of aluminum
ingot was 244 Btu (257 kJ). Of this total, the smelting
processes consumed 196.5 Btu per net ton (2.39 MJ/Mg).
Two-thirds of the total cost of producing aluminum ingot
from bauxite ore is incurred at the smelter, where electric power
is the second largest cost item following the alumina itself
(2-9,2-15). The availability of inexpensive hydroelectricity and
coal explains the location of many plants in the Pacific
Northwest, along the Mississippi and Ohio Rivers, and near the
St. Lawrence River transportation system. All domestic smelters
operate plants to produce thermal power; most purchase
electricity from utilities. New smelters will require about 20
to 25 percent less electricity than existing facilities because
of process modifications (2-12). During 1972 and 1973, 53
percent of the total energy consumed in the industry was derived
from petroleum and natural gas, 36 percent from coal, 10 percent
from hydroelectric power, and 1 percent from nuclear power
(2-16). Power curtailments due to drought conditions forced
significant production cutbacks in 1977 at some smelters that
rely on hydroelectricity. Shortages of natural gas have also
caused problems at some locations in recent years. Recently, the
Bonneville Power Administration announced the intention to
increase rates in 1979 approximately 173 percent for aluminum
smelters located in the Pacific Northwest. This will add about
2-12
-------
$0,044 per pound ($0,097 per kg) to the cost of aluminum produced
in the area (2-17).
A recent estimate indicates that the energy penalties for
total compliance with environmental regulations expected to be in
force by 1985 would be 1 to 2 percent more than the energy
required to produce aluminum in the absence of any regulation
(2-18). Stricter regulation will increase the use of electrical
power because of more widespread use of dry alumina absorption
for control of atmospheric emissions; however, thermal energy
requirements are decreasing because some cryolite recovery plants
are being eliminated at smelters that will no longer use wet
scrubbers.
Outlook—Despite the major problems that face the primary
aluminum industry, the trends in demand, production, shipments,
and prices are steadily upward. Domestic demand for primary
aluminum is expected to be 18 million tons (16.3 Tg) in 2000
(2-7). This represents an average growth rate of 5.2 percent
between 1976 and 2000. It is projected that growth of the
industry will increase rapidly before 1985 and then slow down for
the remainder of the century.
During the first half of 1978, primary aluminum production
rose 4.2 percent over the same period in 1977 (2-19).
Predictions indicate that the total output in 1978 will be
approximately 5.5 percent higher than the total in 1977.
Production in 1978 will not top the record 9.8 billion pounds
(4.4 Tg) of 1974, but projections are that this level will be
2-13
-------
exceeded in 1979. The potlines of domestic producers are now
producing at an average of 92.2 percent of capacity. This
operating rate should increase to the mid-90's by 1979; any
further increase would lead to a decrease in energy efficiency.
Very little additional capacity is expected in the next
several years. Projections indicate that capacity will grow less
than 2 percent annually, at least through 1982. The reasons for
the slow growth in capacity are increased capital costs, energy
costs, and higher rate of return for money invested in fabricated
materials. This slow growth rate, coupled with a high forecast
demand, could force supplies of aluminum to become tight.
As domestic supply becomes tighter, the share of the United
States market commanded by imports will continue to increase
dramatically to meet the demand. In 1977 imports supplied 11.2
percent of the total aluminum market (both primary and
secondary). The import share in 1978 could exceed 14 percent,
and in 1979 it may exceed 15 percent (2-19). Without a large
expansion of plant capacity, imports could control as much as 20
percent of the domestic market by 2000 (2-20). Obviously this
trend will have a negative effect on both the United States
balance of payments and the domestic aluminum industry.
Because the aluminum smelting industry is highly
capital-intensive, rapid technological change is difficult.
Technical competence within the industry, however, will encourage
acceptance of new developments. The major changes to be expected
in the next few years will be additions to smelter capacity and
2-14
-------
installation of additional and improved pollution control
equipment. The trend at primary smelters is toward computerized
control of all operations. Research is progressing in
development of energy-saving technologies; other developments
include new cathodes using hard metals such as titanium diboride,
new cell lining materials, and substitutes for the petroleum coke
used for anodes. Alcoa is testing a new chloride bath
electrolysis process on a semicommercial scale. The process,
based on converting alumina to aluminum chloride, is said to
require 30 percent less energy than conventional Hall-Heroult
electrolysis. Research also continues into more effective dry
absorption technologies to be used in controlling atmospheric
emissions from the reduction cells and anode baking operations at
smelters. Dry scrubbers produce no water effluent and also allow
return of the fluoride values to the reduction cells. Use of dry
scrubbers will be confined to treating the relatively low-volume
primary gas stream because of their high rate of energy
consumption per volume of gas treated.
Because of increasing dependence on foreign sources,
considerable research and development is directed toward the use
of alternative raw materials (nonbauxitic sources) for aluminum
production. In conjunction with industry the Bureau of Mines is
examining such alternatives as clays, feldspar rocks such as
anorthosite, other minerals, and coal wastes. Clays of high
alumina content, consisting mainly of kaolinite, are the most
promising. Pilot plant evaluations were conducted during World
2-15
-------
War II, and research efforts were revived recently. Applied
Aluminum Research Corporation is developing the Toth process,
which directly reduces nonbauxitic ores to aluminum (2-21).
Notwithstanding these development efforts, dependence on foreign
sources is likely to continue for some time until economical
alternative processes are available on a commercial scale.
Process Description
Aluminum is produced by a two-phase operation: bauxite
refining produces a calcined alumina, which is reduced at the
smelter to aluminum. In contrast to processing in most other
nonferrous metals industries, the refinery processes raw
beneficiated bauxite ore from the mine, rather than the metal
itself. Virtually all impurities in the ore are removed during
refining, which is done by the Bayer process. Bauxite refining
produces the largest amount of solid waste associated with
aluminum production. Although it is part of primary aluminum
production, bauxite refining is not discussed here because it is
dealt with in another report. Calcined alumina, both domestic
and foreign, is reduced to aluminum metal at 30 smelters
throughout the country. All smelters use the same process, the
important difference being cell type. Figure 2-1 is a process
flow sheet for the smelting of aluminum.
Aluminum smelting operations are the final steps in
production of aluminum metal. The processes in aluminum smelting
are electrolysis, casting, paste preparation, and, at prebake
anode plants, anode preparation.
2-16
-------
PASTE
PREPARATION
• COKE
PITCH
• ANODE BUTTS
/%
52^
O
*x
Vj/
A
V7 :
ANODE
PREPARATION
PACKING
FINE COKE
ROD YOKE ASSEMBLIES
cementing material
o
ro
I
ANODE
CLEANING
ELECTROLYSIS
CELLS
CASTING
ANODES OR
ANODE PASTE
ELECTROLYTE
CARBON LINERS
- CHLORINE OR INERT GAS
- SALT FLUXES
r*\
_ I ALUMINUM 1
"I METAL J
GAS
^ LIQUID UASTE
9 ATMOSPHERIC EMISSION
SOLID WASTE
- SODIUM ALUMINATE
CAUSTIC
- LIME
- CARBON DIOXIDE
A
UJ «/)
-J u
' O «_)
>-
oc. O
u
Fiqure 2-1. Flow chart depicts primary aluminum
smelting (numbers correspond to process numbers in
text).
-------
Electrolysis Cell—Calcined alumina is reduced to molten
aluminum metal by electrolysis in a bath of molten cryolite, a
double fluoride salt of sodium and aluminum (Process No. 1). The
electrolytic cell, or pot, is a steel container lined with
refractory brick and an inner liner of carbon. The outside
dimensions of the pot range from 6 by 18 ft (1.8 by 5.5 m) to 14
by 42 ft (4.3 by 12.8 m) or larger, with a depth around 3 ft (1
m) (2-11). The pots are arranged in rows, called potlines,
containing 100 to 250 cells electrically connected in series. A
typical smelter contains 250 to 1000 cells. The carbon liner
constitutes the cathode of the cell. The anode of the cell is
also made of carbon, the only material that can withstand the
corrosive action of fluoride in the bath.
The molten electrolytic bath of the reduction cell consists
of alumina, cryolite (NagAlF^), fluorspar (CaF2), and aluminum
fluoride (A1F3). The aluminum fluoride is added to combine with
sodium, present in the alumina as an impurity, to form artificial
cryolite. The addition of fluorspar lowers the melting point of
the bath. The bath is covered by a frozen crust of electrolyte
to diminish heat loss and to protect the anode from oxidation.
Aluminum settles to the bottom of the cell as it is formed
because its density is greater than that of the bath. Every 1 to
3 days, metal is siphoned into cast iron pots with airtight lids
or into large thermally isolated steel crucibles.
The alumina concentration in the bath is usually about 2 to
5 percent, but this decreases as electrolysis proceeds. Failure
2-18
-------
to maintain the concentration above 2 percent results in an
"anode effect," during which the power input to the cell
increases greatly and the temperature of the electrolyte rises
(2-11). This causes the frozen electrolyte crust to melt and the
bath salts to be more easily volatilized, greatly increasing
atmospheric emissions. To control the anode effect and the
resulting increase in pollutant emissions, the crust is broken
before it melts and alumina is added to maintain the
concentration of alumina in the cell.
No solid wastes are generated as an integral part of the
smelting operations because the alumina input contains
essentially no impurities. The principal solid wastes are the
spent anode butts from prebake cells, cracked cathode potliners,
and other such mechanical wastes, which may be contaminated with
fluorides, nitrides, and cyanides. Some plants may process the
materials to recover cryolite, but often the materials are simply
discarded. Potline skimmings are generally returned directly to
the cells.
Solid wastes are generated indirectly during aluminum
smelting by operation of air pollution control devices and by
wastewater treatment. Effective control requires collection of
both particulate matter containing fluorides and gaseous
fluorides. Emission collection is either primary (cell hooding),
secondary (roof monitors), or both. Primary control is either by
dry or wet scrubbing. Dry scrubbing with alumina is the best
control method in current use because the scrubbing system both
2-19
-------
adsorbs gaseous fluorides and mechanically collects particulate
matter. In each of the several dry scrubber designs now in use,
alumina is used to adsorb the fluoride and then is collected with
other particulates in fabric filters. The alumina and collected
particulates are then recycled to the cells. Dry scrubbing of
potline gases creates little solid waste because all material
collected is returned to the process; the only solid waste is the
worn bags. In wet primary control systems multiple cyclones or
an electrostatic precipitator first removes particulate matter
from the gas stream, then a wet scrubber removes gaseous
fluorides. Collected particulates are recycled to the cell, and
the scrubber liquor is pumped to a wastewater treatment facility.
Where secondary control equipment is used, it is usually a
low-energy wet control device such as a spray screen. Liquid
wastes from wet scrubbers are treated either in a once-through
lime treatment system or a treat-and-recycle system.
Once-through treatment generates a solid waste of calcium
fluoride that must be disposed of. The treat-and-recycle system
can be operated either to recover cryolite or simply to allow
production of a calcium fluoride solid waste. The cleaned water
is then recycled to the scrubber.
The three types of reduction cells used in domestic aluminum
smelters differ primarily in anode configuration and method of
alumina addition. Prebake cells, in which the anodes have been
previously formed, graphitized, and attached to rods, account for
two-thirds of the domestic aluminum capacity. Individual anode
2-20
-------
assemblies are attached to an anode bus bar, in which their
height can be adjusted as they are consumed. These assemblies
are usually installed in two rows extending the length of the
cell. Anodes in the cell are replaced by new anode assemblies
before they are entirely consumed.- Prebake cell design
facilitates collection of atmospheric emissions, permits larger
production capacity per cell, and enhances electrical efficiency.
The other two cell types, VSS and HSS, are continuous anode
designs. In both, the anode paste is baked in the cell. The
paste is fed into the open top of a rectangular steel compartment
suspended above the cell and rammed down into the casting, where
it is gradually baked by the heat created by the electrical
resistance of the carbon. The paste forms into a monolithic
solid about 1.5 ft (0.5 m) above the bath surface (2-11). The
difference between the two types of Soderberg cells is the method
by which the anode is supported in the cell and electrical
contact is made. In VSS cells the anodes are supported and
electrical contact is made by steel or aluminum studs inserted
vertically into the anode as it is baked. In HSS cells the studs
are inserted horizontally into the anode paste. The current
trend in industry is to replace Soderberg cells with prebake
cells.
Casting—Molten aluminum from the cells is cast into salable
shapes (Process No. 2). At some plants, the molten aluminum is
batch-treated in furnaces before casting to remove oxides,
gaseous impurities, and active metals such as sodium and
2-21
-------
magnesium. This process most often consists of adding a flux of
chloride and fluoride salts and then bubbling chlorine, often
mixed with an inert gas, through the molten mixture. Chlorine
reacts with impurities to form hydrogen chloride or metal
chlorides. The dross or scum that forms floats on top of the
molten aluminum and is removed prior to casting. The dross is
usually held in a small furnace to reclaim entrained aluminum
particles (2-11). After cleaning, it may be discarded in an
onsite landfill, from which secondary water pollution is
possible; more often, however the dross is sold to secondary
aluminum smelters (2-11). After final removal of impurities,
aluminum is cast into ingots and bars for sale.
Paste Preparation—In addition to potlines, Soderberg and
prebake smelters contain the facilities to manufacture the paste
used in the anodes and cathodes of the electrolytic cells
(Process No. 3). The paste is a mixture of petroleum and pitch
coke mixed with a pitch binder. The paste preparation plant, or
"green mill," includes facilities that crush, grind, screen, and
classify the coke. Spent anode butts may also be part of the
feed material at plants using prebake cells. In Soderberg anode
preparation, the hot thick paste is transferred directly to the
potroom. In prebake anode preparation, the mixture is
transferred to molds where "green" anodes are formed either in
hydraulic presses or by vibratory jolting. The only emissions
from paste preparation are particulate matter and some fume from
the crushing, grinding, and hot mixing operations.
2-22
-------
Most smelters use fabric filters to reduce these emissions;
electrostatic precipitators, multiple cyclones, and wet scrubbers
are also used (2-11). The collected particulate matter is
usually recycled to the process, however if not recycled it
represents a solid waste.
Anode Baking—Green anodes formed in the paste plant for
prebake cells must be baked to achieve thermal stability and good
electrical conductivity (Process No. 4). Ring-type furnaces (the
most common) and tunnel kilns are used domestically for this
purpose. After thorough cooling, the baked anodes from either
type of furnace are air-blasted with fine coke or brushed to
remove fines and adhering material. They are then transferred to
a rodding room, where rod yoke assemblies are connected to the
carbon anodes with a cementing material, usually molten iron.
The anodes are then sprayed with molten aluminum to prevent
unnecessary oxidation in the pot. Anode baking solid wastes are
principally the scrap brick removed during furnace rebuilding.
Some plants clean the furnace off-gases in scrubbers, which may
generate a solid waste.
Anode Cleaning—The spent anode butts from prebake cells are
recycled for carbon values (Process No. 5). In the same rodding
room used in anode preparation, the thimbles forming the
connection between the anode butts and the current-carrying rod
supports are cracked off and both the rod stubs and anode butts
are cleaned by grit blasting. The cleaned anode butts are then
sent to the anode paste preparation plant. Contaminated and worn
2-23
-------
out grit is the only solid waste from anode butt cleaning. Air
emissions include dust from shotblasting, aluminum oxide,
cryolite, and possibly other fluorides. Fabric filters are
typically used for control; the collected dust is combined with
the grit from anode cleaning and discarded.
Cryolite Recovery—Many smelter wastes contain recoverable
fluoride, which is reclaimed in the form of cryolite to be
returned directly to the reduction cells (Process No. 6). Bleed
liquor from wet scrubbers, solids from wastewater clarifiers,
wash water from the cleaning of discarded potliners, and
discarded alumina pot insulation can all be treated for cryolite
recovery. The processing consists of allowing sodium aluminate
to react with soluble fluorides so that the cryolite is
precipitated for recovery. The only solid wastes are undissolved
solids and scrap cathode potliners, which usually are transferred
to waste heaps or surface impoundments for disposal. The extent
to which cryolite recovery is practiced at domestic smelters is
not known.
Solid Waste Characterization
Sources and Quantities of Solid Waste
This section deals with the sources and quantities of solid
waste produced at domestic primary aluminum plants. Quantities
of solid waste produced are calculated for three model plants
that represent typical aluminum smelters. Finally model plant
data are used to calculate state, regional, and national totals
of solid waste generation.
2-24
-------
No attempt is made to analyze the generation of solid wastes
at each of the 30 domestic primary aluminum plants; rather, the
model plants were developed by the following procedure.
Processes used in the aluminum industry were analyzed to
determine their generation of solid wastes. Solid waste
quantities were estimated for main process operations (e.g.,
electrolysis, casting) and for auxiliary operations (e.g., paste
plant, air and water pollution control). Information on solid
waste quantities was collected from published literature, from
in-house files and by plant visits. The data were used to
calculate average solid waste generation factors based on the
quantity of aluminum produced. The generation factors were
applied in calculating total solid waste production by the model
plants. The factors were also used in calculating the total
quantity of solid waste produced by actual plants that are
represented by the models.
• Because all domestic aluminum plants except the new Alcoa
chloride process plant use Hall-Heroult technology, some solid
wastes are common throughout the industry. These include spent
potlinings from the electrolysis cells (or pots) and dusts
collected during casthouse skims processing. Other solid wastes
produced by primary aluminum smelters depend on the process
operations, which vary among individual plants according to (1)
type of anode cell configuration used for electrolysis, (2) type
of primary air pollution control device (wet or dry), (3) whether
cryolite recovery is practiced, (4) whether anode preparation
2-25
-------
(anode pressing and baking) is practiced. Among these variables
the type of air pollution control device is the single most
important factor affecting solid waste generation.
In estimating quantities of solid waste from the primary
aluminum industry, consideration is given to several important
industry trends that will affect solid waste production by this
industry: (1) dry scrubbing for air pollution control will
probably be used at new aluminum plants and is likely to replace
wet scrubbing at many existing plants, (2) cryolite recovery will
decrease as the wet emission control devices are replaced with
dry systems, (3) new plants and plant1 expansions will likely use
prebake anodes rather than either type of Soderberg cell.
The three model plants are based on current industry
practices: Model 1 represents plants using dry scrubbers, Model
2 represents those using wet scrubbers, and Model 3 represents
those plants using both wet and dry scrubbers. Differences in
solid waste production associated with anode type are accounted
for by adding auxiliary operations and corresponding solid waste
generation factors. None of the models is applicable to Alcoa's
new chloride process plant; no model was developed because this
plant represents only a small percentage of total industry
production and not enough information is available for
calculating the quantities of solid waste it generates.
The model plants reflect the differences in air pollution
control practices because these have significant impact on solid
waste generation. Plants using wet scrubbers generate large
2-26
-------
quantities of sludge as a result of liming and settling the
scrubber liquors. In contrast, plants using dry systems recycle
all collected particulates and therefore produce no solid waste.
The models are designed to accurately represent current industry
practices and also to enable prediction of future solid waste
generation as the trend to dry scrubbers continues.
Although an attempt is made to quantify all inputs and
outputs to each process, the quantities given in the model plant
flow diagrams do not represent complete material balances. The
quantities are intended only to represent the amount of solid
waste to be expected from an aluminum plant producing the
indicated amount of primary aluminum metal.
Model 1: Dry Scrubbing of Potline Gases—This model
represents a primary aluminum plant using dry air pollution
control on the potline off-gases (Figure 2-2). The model plant
has an annual capacity of 173,000 tons (156.9 Gg) per year or a
daily capacity of 474 tons (430 Mg). For the purposes of
calculating solid waste production, it is assumed that the plant
operates at 91.9 percent of capacity, the 1977 industry average.
The capacities of operating plants represented by this model
range from 36,500 tons (33 Gg) per year to 280,000 tons (254 Gg)
per year. The model represents 13 plants, having a total
capacity of 2,126,000 tons (1.3 Tg) per year, or 42.8 percent of
domestic capacity. Of the 13 plants, 12 use prebake anodes and
the other uses HSS anodes.
2-27
-------
INITIAL
MATERIALS
HANOI INC
A
CCEIL OFrCAS \
TO MY SCRUBBER J
DRY
SCRUBBER
JL
OFFGAS J
fO
NJ
00
ELECTROLYSIS
CELL
MOOCS
ANOOC PASTE 81 1
ELECTROLYTE 11 4(
CARBON
POUINERS 2 95
/ SPENT
' ANOOC WJTTS )
POTL NERS
AftOOl
CLEANING
/ \
/SHOT\
/ BLAST \
/ OUST \
NOTE- NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
CASTING
.
-CHLORIDE AND/OR
INERT CAS
- SALT FLUXES ? 79
- ALLOYING WTALS
/ SKIMS TO SECONDARY'S
' A1 PJANT )
—• A 1L- —¦ ^
/ \
/5o \
i
I assL
.-s_r
.5s '
\ /
L.
SKIMS
\ s 97
~ 1
I
SKINS
HETAL ,
"J RECOVERY r~*
j TURNACE_ |
'Tkins TO SECONDARYN
A1 PLANT )
¦««. ^ 4 14
y
A
I ~ i
i h
I 5° I
» /
ALUMINUM
I b9
L
i
J BAGHOUSE
i _j
/ \
/ \
/casthouse\
/ OUST \
n ?« \
Figure 2-2. In the primary aluminum industry, Model 1
represents plants with dry scrubbing.
(continued)
-------
to
I
K>
1X1
DUSTS RECYCLED
PASTE PREPARATION
BAGHOUSE
PARTICULATES
( ALUMINA RECYCLED
S ^
DRY
SCRUBBER
GASES DIRECTLY
TO ATMOSPHERE
\
r*—-1—1
•— A I IIMIUA I
"ALUMINA
T
PASTE
PREPARATION
A
r
~~T
i_^
GASES FROM
ANODE BAKING
/
T
o t~
O 1/1
a= <
•X a.
- COKE
- PITCH
- CLEANED
ANODE
BUTTS
r*L.
ANODE
PREPARATION
C\
, t/> F- 1
I
- PACKING
-FINE COKE
- ROD YOKE
ASSEMBLIES
I-CEMENTING
MATERIAL
\ I
\ /
I
i
/ \
/SCRAP\
/FURNACE \
' BRICK \
_ \
/"
1
I
WET
SCRUBBER
i—»-i || h*i lagoon j—h
\
\ i
I
pi i
HATER ^
I
I
\ I
\ /
I I
ri tj
lLIME OR 1
LIMESTONE
I
Jt
V.
/ \
/ \
/ SLUDGE \
£_!L8.L_\
NOTE-
NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 2-2. (continued)
-------
The model includes four sources of solid waste. One occurs
at all plants, two result from auxiliary operations at the 12
prebake plants, and the other results from processing casthouse
skims. Although not all plants process casthouse skims, most do
recover metal from the skims. Therefore in calculation of solid
waste totals it is assumed that all plants process casthouse
skims.
The largest quantity of solid waste consists of scrap
potliners that are removed from the electrolysis cells. The cell
interiors are lined with carbon, one of the few materials that
can withstand the effects of fluorides in the bath. When the
cell is lined, a carbon paste or a combination of paste and
carbon blocks is rammed into the cell to form a solid liner that
contains the bath and prevents contamination of the aluminum.
After 3 or 4 years of operation the potliner breaks down and
contaminates the molten aluminum with iron from the outer shelf
of the cathode; when this occurs, the liner must be replaced.
Scrap potliners amount to 5880 tons (5.33 Gg) per year or 74
pounds per ton (37 kg per Mg) of aluminum produced (2-22).
Plants using prebake anodes have two additional sources of
waste. The first results from cleaning of anode butts before
they are recycled to the paste plant. Anodes that have been
consumed during alumina reduction in the cell are replaced,
leaving an anode butt. Shotblast dust is collected during the
cleaning of adhering bath material from the anode butt. Dust
amounts to 800 tons (730 Mg) per year or 10 pounds per ton (5 kg
2-30
-------
per Mg) of aluminum produced; this material is collected and
discarded, usually with the potliners (2-23).
The second source of waste from prebake plants results from
anode preparation. Green anodes are formed and baked into a
monolithic solid in furnaces. Furnace operations produce scrap
brick and a gas stream that must be cleaned. Scrap brick removed
from the furnace as necessary during rebuilding amounts to 5100
tons (4.62 Gg) per year or 64 pounds per ton (32 kg per Mg) of
aluminum produced. Anode baking off-gases can be cleaned by wet
or dry scrubbing although most plants do not clean the gases
(2-10). Those plants which use dry scrubbing on the potliners
and do clean the anode baking off-gases generally also use dry
scrubbing controls on the off-gases. Therefore there are no
solid wastes associated with anode baking air pollution control
equipment.
The remaining source of solid waste is processing of
casthouse skims. Aluminum plants may purify aluminum from the
cell before casting by adding fluxes to form a dross that
contains metal oxides and metal. The dross is either sold
directly to secondary aluminum plants for metal recovery or
processed onsite to recover part of the contained metal before it
is sold to the secondary plants. During onsite processing a
baghouse collects 400 tons (360 Mg) of particulates per year, or
5 pounds per ton (2.5 kg per Mg) of aluminum produced (2-23).
An aluminum plant producing 159,000 tons (144 Gg) per year
of aluminum metal using Soderburg type anodes and processing
2-31
-------
metal skims would be expected to produce solid wastes totalling
6,300 tons (5.7 Gg) per year, or 79 (39.5 kg per Mg) pounds per
ton of aluminum produced. A prebake aluminum plant of this type
and size would be expected to produce a total of 12,200 tons
(11.0 Gg) per year, or 153 pounds per ton (76 kg per Mg) of
aluminum produced. Total solid wastes produced at plants
represented by Model 1 are given in Table 2-3.
Model 2: Wet Scrubbing of Potline Gases—Model 2 represents
an aluminum plant using a wet scrubber to control emissions from
the potline (Figure 2-3). Capacity of the model plant is 164,500
tons (149 Gg) per year, or 451 tons (409 Mg) per day. Again, for
calculation of solid waste production, plant operation at 91.9
percent of capacity is assumed. Capacities of actual plants
represented by this model range from 68,500 tons (62 Gg) per year
to 260,000 tons (236 Gg) per year. The model represents eleven
aluminum plants having a total annual capacity of 1,633,500 tons
(1.36 Tg) and constituting 32.9 percent of the industry.
The model includes plant variations like those in Model 1,
concerning cell type and skim processing, along with cryolite
recovery, which may be practiced at plants using wet scrubbing.
The solid wastes produced at this plant that differ from those
produced by Model 1 are primarily sludges from treatment of
scrubber liquor.
Model 2 has five sources of solid waste. Four are
counterparts of the sources associated with Model 1: spent
potliners from the electrolysis cells, dust from anode butt
2-32
-------
TABLE 2-3
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY ALUMINUM
PLANTS REPRESENTED BY MODEL 1*
Waste type
Waste
generation factor
(lb/ton of product)
Annual solid
waste production
(tons/year)
Potliners
74
72,000
Scrap brick+
64
60,000
Shotblast dusts+
10
9,000
Casthouse dusts
5
5,000
Total
146,000
* Total production of all plants represented by this model
is 1,954,000 tons/year.
^ Total production of plants expected to produce this waste
is 1,880,000 tons/year.
Note: Metric conversion table is given in front matter.
2-33
-------
MOTE- NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR.
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
N>
I
OJ
INITIAL
NAT(P|AL$
HAND [Nf.
/ SPENT ANODE "\
Buns /
1 ANODE
I CLEANING
L_
c1-
Lgr
x
/ blast \
/ OUST \
SCRUBBER
CLLL
pffgas
ELECTROLYSIS
CELL
- ANODE 0"
ANODE PASTE 77
- ELECTROLYTE 10
CAR80N
POTLINERS 2 79
P0U1NERS
/ \
/spent\
AOUINER^
/ 5 59
CRYOLITE
RECOVERY
CRYOLITE
-SODIUM
ALIK1NATT
-CAUSTIC
LIHE
CARBON
DIOXIDE
KESTOM OR
/s\
Is \
I er I
"1 uj «- r-il
123 I
\sl I
\"o I
<¦/
A
/ \
. SLUDGE \
110 \
/ \
! 3 *
-J IS I
i §3 I
' O I
\ /
/ \
/ s«\
I *S *
-(I
CASTING
A
x
\
-CHLORINE AND/OR
INERT GASES
-SALT FLUXES ? 38
AlLOYIfb
METALS
CASTHOUSE
SKIMS
SKIMS TO
CASTING
C SECONDARY Al PLANT 1
SKINS
/IftYOllTEX
/RECOVERY v
/ SLUDGE \
L — LL«_ _\
n-t—,
| SKIHS METAL I
-» RECOVERY 'r-
' niDHarr 1
I
_ JL_
-—" stems to~~ N
SECONDARY Al PLANT »
^ ^ 3 94 ^
/ \
S3 |
\ /
I
Jt
/ \
/CASTHOUSE^
/ DUST \
Figure 2-3. In the primary aluminum industry Model 2 represents
plants with wet scrubbing.
(cor
-------
DUSTS RECYCLED TO
.PASTE PREPARATION
M
I
U>
cn
BAGHOUSE
O
PARTICULATES
PASTE
PREPARATION
-COKE
-PITCH
( ALUMINA RECYCLED ^
~~ T~~^
i
DRY
SCRUBBER
i-*'
L A,
s
\
GASES DIRECTLY
TO ATMOSPHERE
y
T
-ALUMINA
GASES FROM
ANODE BAKING
A
\
uj ui
O 1—
O to
z «=t
< a-
r
i
ANODE
PREPARATION
\J
NOTE-
"-CLEANED
ANODE
BUTTS
NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOU ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
- PACKING
-FINE COKE
-ROD YOKE
ASSEMBLIES
LCEMENTING
MATERIAL
I
/ \
/SCRAF*
.'FURNACE'
' BRICK >
4.8
O UJ 1
12°
I
"J
/
'o UJ ,
/-£ \
I ac<
HET
SCRUBBER
r~
i
i
T
I
Figure 2-3. (continued)
-------
cleaning, furnace scrap and gases, and dust from processing of
casthouse skims (again it is assumed that all plants process
casthouse skims).
The fifth type of solid waste in Model 2 comes from
treatment of the wet scrubber liquor, which contains fluorides
that must be treated before the liquor can be recycled or
discharged. Scrubber liquor is treated with lime or limestone to
precipitate the fluoride. The treated water is held in a lagoon
to allow settling of the solids before the water is recycled or
discharged. Settled solids amount to 11,000 tons (10.0 Gg) per
year, or 146 pounds per ton (73 kg per Mg) of aluminum produced;
these solids are periodically dredged from the lagoon, dried, and
stored (2-10).
Scrap potliners result from the operation of the cells, as
described in Model 1. Scrap potliners amount to 5,590 tons (5.07
Gg) per year, or 74 pounds per ton (37 kg per Mg) of aluminum
produced are removed from the cells each year (2-22).
Recovery of cryolite (Na^AlF^) is practiced at some plants
as an alternative to treating scrubber liquor and scrapping
potliners to recover fluoride values in a form that can be
readily used in the electrolysis cells. Scrubber liquor and
potliner leach solution are combined, sodium aluminate is added,
and cryolite is precipitated from the solution. The process
leaves a residue of scrap potliners and undissolved solids.
Solid waste from cryolite recovery totals 11,600 tons (10.5 Gg)
per year, or 154 pounds per ton (77 kg per Mg) of aluminum
2-36
-------
produced (2-10). At plants practicing cryolite recovery, the
solid waste from this source replaces both that from treating
scrubber liquor and that from spent potliners.
Like other prebake cells, prebake cells at a plant using wet
scrubbing have two additional sources of solid waste. Cleaning
of anode butts generates shotblast dusts amounting to 755 tons
(684 Mg) per year, or 10 pounds per ton (5 kg per Mg) of aluminum
produced. Scrap furnace brick amounts to 4800 tons (4.38 Gg) per
year, or 64 pounds per ton (32 kg per Mg) of aluminum; this scrap
is removed from the furnace during rebuilding. Furnace off-gases
are sometimes treated either by dry scrubbing, which produces no
solid waste, or by wet scrubbing, from which the liquor is
combined with potroom scrubber liquor for treatment and disposal.
Finally, the onsite processing of casthouse skims generates
an off-gas containing particulates, which are removed by fabric
filters. Casthouse dusts amount to 380 tons (345 Mg) per year,
or 5 pounds per ton (2.5 kg per Mg) of aluminum produced.
An aluminum plant represented by this model, with an assumed
annual production of 151,000 tons (137 Gg) of aluminum by
Soderberg type anodes and processing casthouse skims, would be
expected to produce solid wastes totalling 17,000 tons (15.4 Gg)
per year, or 225 pounds per ton (113 kg per Mg) of aluminum. A
prebake aluminum plant of this type and size would be expected to
produce solid wastes totalling 22,600 tons (20.5 Gg) per year, or
299 pounds per ton (150 kg per Mg) of aluminum. The total solid
2-37
-------
wastes produced at plants represented by Model 2 are given in
Table 2-4.
Model No. 3: Aluminum Plants with Both Wet and Dry
Scrubbing—Model 3 represents an aluminum plant using both wet
and dry scrubbers to control emissions from the potline (Figure
2-4). Capacity of the model plant is 164,500 tons (149 Gg) per
year or 451 tons (409 Mg) per day. Again, for calculation of the
solid waste production, plant operation at 91.9 of capacity is
assumed. Capacities of actual plants represented by this model
range from 189,000 tons (171 Gg) per year, or 518 tons (470 Mg)
per day to 285,500 tons (259 Gg) per year, or 782 tons (709) per
day. The model represents five aluminum plants having a total
annual capacity of 1,171,500 tons (977 Gg) per year, or 23.6
percent of current domestic capacity.
The model includes variations like those in Model 1,
concerning cell type and skims processing. Model 3 has five
sources of solid wastes, counterparts of the sources associated
with Model 2: scrap potliners from the electrolysis cells,
shotblast dust from anode butt cleaning, scrap furnace brick,
casthouse dust (again it is assumed that all plants process
casthouse skims producing the dust), and sludge from the
treatment of scrubber liquor.
Model 3 plants remove fluorides from electrolytic cell
off-gases with both types of scrubbers described earlier. For
the purpose of this study it is assumed that half of the
electrolytic cells are controlled by wet scrubbing, since the
2-38
-------
TABLE 2-4
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY ALUMINUM
PLANTS REPRESENTED BY MODEL 2*
Waste type
Waste
generation factor
(lb/ton of product)
Annual solid
waste production
(tons/year)
Potliners+
74
50,000
Scrubber sludge"^
146
99,000
Cryolite recovery
sludge§
154
9, 000
Shotblast dusts11
10
9,400
Scarp brick^
64
25,000
Casthouse dusts
5
3, 000
Total
191,000
* Total production of all plants represented by this model
is 1,245,000 tons/year.
t Total producti n of all plants expected to produce this
waste is 1,125,500 tons/year.
§ Total production of all plants expected to produce this
waste is 119,500 tons/year.
^ Total production of all plants expected to produce this
waste is 539,000 tons/year.
Note: Metric conversion table is given in front matter.
2-39
-------
f \
to
I
o
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
•go
WATER
-H
SLUDGE
sot]
CELL OFFGAS
-
ANODES OR
ANODE PASTE 77
ELECTROLYTE
_ CHLORINE AND/OR
INERT GASES
-SALT FLUXES 2 M
L ALLOYING METALS
SPENT ANODE
BUTTS
SKINS TO N
SECONDARY A1 PLANT J
CASTING
SKIMS
r
I—
I 1
ANODE
CLEANING
I
t__
** SKIMS TO
( SECONDARY A1 PLANT
3 94 ^
ORY
SCRUBBING
INITIAL
MATERIAL
HANDLING
CASTING
ESP
ELECTROLYSIS
CELL
/ HOUSE \
/ DUST \
L OJ3 i
Figure 2-4. In the primary aluminum industry, Model 3 represents
plants with both wet and dry scrubbing.
(cont ;d)
-------
fsj
I
( ALUMINA RECYCLED ^
I ' I
J DRY 1
I SCRUBBER •
I 1
| WET J
1 SCRUBBER r
GASES DIRECTLY \
TO ATMOSPHERE /
GASES FROM
ANODE BAKING
ANODE
"**; PREPARATION
h-H
— COKE
— PITCH
-CLEANED
ANODE
BUTTS
- PACKING
-FINE COKE
-ROD YOKE
ASSEMBLIES
-CEMENTING
MATERIAL
BAGHOUSE
PASTE
PREPARATION
/
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
/ \
/SCRA(*
/FURNACE^
' BRICK \
4.8 \
'V
Figure 2-4.
(continued)
-------
proportion of wet to dry scrubbing at all five plants is unknown.
The scrubber liquor is neutralized with lime or limestone to
precipitate the fluoride. The treated water is held in surface
impoundments to allow settling of the solids before recycle or
discharge. Settled solids amount to 5,500 tons (5.0 Gg) per
year, or 73 pounds per ton (37 kg per Mg) of aluminum produced.
The Model 3 sludge generation factor is half of the Model 2
generation factor since only half of the cells are controlled by
wet scrubbing (2-10).
Scrap potliners result from operation of the cells, as
described in Model 1. Scrap potliners amounting to 5,590 tons
(5.07 Gg) per year, or 74 pounds per ton (37 kg per Mg) of
aluminum produced, are removed from the cells each year (2-22).
The prebake cells at a plant using wet scrubbing have two
additional sources of solid waste. As at all prebake plants, the
cleaning of anode butts generates shotblast dusts amounting to
755 tons (684 Mg) per year, or 10 pounds per ton (0.5 kg per Mg)
of aluminum produced. Scrap furnace brick amounts to 4,800 tons
(4.38 Gg) per year, or 64 pounds per ton (32 kg per Mg) aluminum
produced. This scrap is removed from the furnace during
rebuilding. Off-gases from the anode baking furnace either are
not controlled; are cleaned in a dry scrubber, which produces no
solid waste; or are cleaned in a wet scrubber from which the
liquor is combined with the potroom scrubber liquor for treatment
and disposal.
2-42
-------
Finally, the onsite processing of casthouse skims generates
a furnace off-gas, which is cleaned by fabric filters. Collected
casthouse dust amount to 380 tons (340 Mg) per year, or 5 pounds
per ton (2.5 kg per Mg) of aluminum produced (2-23).
An aluminum plant represented by the model, with an assumed
annual production of 151,000 tons (137 Gg) by Soderburg type
cells and processing metal skims, would be expected to produce
solid wastes totalling 11,500 tons (10.4 Gg) per year, or 152
pounds per ton (76 kg per Mg) of aluminum. A prebake aluminum
plant of this type and size would be expected to produce solid
wastes totaling 17,100 tons (15.5 Gg) per year, or 226 pounds per
ton (113 kg per Mg) of aluminum produced. Total solid waste
produced by these five plants is 106,000 tons (96.2 Gg) per year
(Table 2-5).
National Solid Waste Totals
This section presents the state, regional, and national
totals of solid waste attributable to the aluminum industry.
Total solid waste generated by all models is 451,000 tons (409
Gg) per year (Table 2-6). Spent potliners* represent the largest
quantity of waste, accounting for 37 percent of the total.
Scrubber treatment sludges are second at 33 percent and scrap
* It should be noted that the yearly generation of spent
potliners at all plants calculated with the average generation
factor is 168,000 tons (152 Gg) per year. However the reference
in which the average generation of 188,000 tons (171 Gg) per
year (2-22). The difference is attributed to more accurate
industry production statistics available to the author.
2-43
-------
TABLE 2-5
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY ALUMINUM
PLANTS REPRESENTED BY MODEL 3*
Waste type
Waste
generation factor
(lb/ton of product)
Annual solid
waste production
(tons/year)
Potliners
74
40,000
Scrubber sludge
73
39,000
Shotblast dusts+
10
3,000
Scrap brick+
64
21,000
Casthouse dusts
5
3,000
Total
106,000
* Total production of all plants is 1,076,500 tons/year.
^ Total production of all plants expected to produce this
waste is 645,000 tons/year.
Note: Metric conversion table is given in front matter.
2-44
-------
TABLE 2-6
1978 NATIONAL SOLID WASTE TOTALS FOR THE PRIMARY
ALUMINUM SMELTING INDUSTRY
(tons/year)
Quantity
generated at
plants represented
by:
Waste type
Model 1
Model 2
Model 3
Total
Potliners
72,000
56,000
40,000
168,000
Scrap brick
60,000
25,000
21,000
106,000
Shotblast dusts
9, 000
4,000
3,000
16,000
Casthouse dusts
5, 000
4, 000
3, 000
12,000
Sludge
110,000
39,000
149,000
Total
146,000
199,000
106,000
451,000
Note: Metric conversion table is given in front matter.
2-45
-------
brick next, at 24 percent. These percentages show that shotblast
and casthouse dusts are minor quantities of solid waste.
Aluminum plants are distributed throughout the country with
the highest concentrations in the Northwest and the South, where
inexpensive electrical power is available (Table 2-7). The
greatest quantities of solid wastes are generated in EPA Region
3, where 23.5 percent of domestic capacity is located. Five of
seven plants in the region use wet scrubbers either totally or
partially for air pollution control and therefore generate large
quantities of scrubber sludge. EPA Region 10 is second in total
amount of solid waste produced, even though it has more plants
(nine) and a larger percentage of capacity (28.6). This is
because most plants in Region 10 use dry scrubbing for air
pollution control.
National Solid Waste Projections
Future solid waste quantities (Table 2-8) are estimated by
multiplying solid waste generation factors by the projected
aluminum production (Table 2-1) for the years 1980, 1985, and
1990. The projected solid waste quantities are based on the
following assumptions:
1. Current solid waste generation factors developed for
the model plants will remain constant.
2. New aluminum plants and plant expansions will all be
prebake plants.
3. All new aluminum plants will use dry scrubbing for air
pollution control.
2-46
-------
TABLE 2-7
GEOGRAPHICAL DISTRIBUTION OF SOLID WASTE FROM THE PRIMARY
ALUMINUM SMELTING INDUSTRY
(1978)
Annual solid
Annual regional
Number
waste production
solid waste production
EPA Region
State
of plants
(tons/year)
(tons/year)
II
New York
2
29,000
29,000
III
Maryland
1
12,000
West Virginia
1
11,000
23,000
IV
Alabama
2
36,000
Kentucky
2
36,000
North Carolina
1
13,000
Tennessee
2
43,000
128,000
V
Indiana
1
20,000
Ohio
1
36,000
56,000
VI
Arkansas
2
16,000
Louisiana
2
21,000
Texas
2
30,000
67,000
VII
Missouri
1
10,000
10,000
VIII
Montana
1
19,000
19,000
X
Oregon
2
28,000
Washington
7
91,000
119,000
National Total
30
451,000
451,000
Note: Metric conversion table is given in front matter.
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TABLE 2-8
PROJECTED SOLID WASTE FROM THE PRIMARY ALUMINUM
SMELTING INDUSTRY
Projected solid waste
(tons/year)
Waste type
1980
1985
1990
Potliners
202 300
276,500
329,400
Scrubber sludge
141,500
139,300
139,300
Scrap brick
135,700
199,900
245,600
Shotblast dusts
31,200
31,200
38,400
Casthouse dusts
13,700
18,700
22,300
Total
514,400
665,600
775,000
Note: Metric conversion table is given in front matter.
2-48
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4. Five percent of current capacity using wet scrubbers
will replace them with dry scrubbers by 1980 and an
additional 3 percent will convert by 1985. No further
changes are assumed for 1990.
5. More stringent air and water quality regulations will
not cause a substantial increase in quantities of solid
waste because current control equipment has high
overall efficiency and any increase will be small
compared to the decrease, caused by factors in
assumption 4 above (2-11).
Each of these assumptions is realistic considering the
recent increase in use of prebake cells and the economic and
environmental advantages of dry scrubbing (2-24). Perhaps the
least realistic assumption is that concerning the effects of air
and water regulations. More stringent air regulations on release
of fluorides may force the industry to use secondary scrubbing if
primary collection and scrubbing cannot achieve compliance with
the regulations. Secondary scrubbers currently used are wet
scrubbers, and any increase in their use will increase the amount
of scrubber sludge requiring disposal. It would be extremely
difficult to provide a reasonable estimate of the quantity of
solid waste resulting from increased secondary scrubbing because
all air regulations have not been promulgated and current
standards could be altered.
A recent study dealt specifically with the potential impacts
of air and water pollution control regulations, addressing the
Clean Air Act of 1970, Federal Water Pollution Control Act of
1972, and amendments to both Acts (2-24). The researchers
attempted to compensate for the numerous variables that will
affect future solid waste generation resulting from environmental
2-49
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regulations. They began with data for 1967 and 1977, then
projected low and high values for 1980, 1984, and 1987 according
to conditions established in a minimum and a maximum scenario
(Appendix B). The study indicates that between 841,400 and
1,036,400 tons (763 and 940 Gg) per year of sludges from air and
water pollution control will be produced in 1987 (Table 2-9).
Thus pollution control regulations may have a significant effect,
since the projected quantity of sludge is a substantial increase
over current levels.
The projected quantities are misleading, however, because
they do not take into account the effect of replacing wet
scrubbing with dry scrubbing nor do they factor out production
increases to show only increases due to air and water quality
regulations.
Two other factors not considered in the solid waste
projections are the potential for recycle of potliners and the
possibility of a new process for aluminum production. Discarded
potliners contain valuable materials, such as carbon and fluoride
compounds. Although most plants do not now recycle potliners
because it is not economical, any shift in economics due to
higher cost of raw materials or to a new inexpensive recovery
process could result in most potliners being recycled. A new
aluminum reduction method, Alcoa's chloride process, is being
tested at a small plant. It does not appear that the new process
will represent a significant percentage of future production
capacity.
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TABLE 2-9
TOTAL ANNUAL SLUDGE FROM ALUMINUM SMELTING ATTRIBUTABLE
TO AIR AND WATER QUALITY REGULATIONS*
(1000 tons/year dry weight)
Historic Minimum scenario^ Maximum scenario"!"
Legislation 1967 1977 1980 1984 1987 1980 1984 1987
Water pollution
control
act
45
207
239
291
318
254
378
414
Clean air
act
189
366
382
480
523
466
585
622
Total
234
573
621
771
841
720
963
1036
* Office of Solid Waste. Comprehensive Sludge Study Relevant to Section 8002(g)
of the Resource Conservation and Recovery Act of 1976 (PL 94-580). V.l. Environmental
Protection Control No. 68-91-3945. Washington.
+ See Appendix B for explanation of scenarios.
Note: Metric conversion table is given in front matter.
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Overall, the projections indicate that scrap potliners will
continue to constitute the greatest quantity of solid waste from
the aluminum industry. Scrap brick will replace sludges as the
second largest quantity of solid waste. As a result of the
increased use of dry scrubbers, the quantities of sludge will
decrease, as will their percentage of the total solid waste. The
decrease will overshadow increases due to new air and water
regulations unless secondary scrubbing becomes necessary.
Secondary scrubbing will undoubtedly increase the amount of
sludge attributable to air pollution control; disposal of sludge
will not present unusual technical difficulties, although it will
present a cost burden. Shotblast dusts and casthouse dusts will
remain minor components of the solid waste.
Qualitative Characteristics of Solid Wastes
Although the composition of solid waste produced at a
primary aluminum plant is variable, two elements, carbon and
fluorine, are common to virtually all the wastes. Carbon is the
primary constituent of spent potliners, and fluoride is a major
constituent of scrubber sludge, the two largest categories of
solid waste produced at aluminum plants.
Scrap potliners are produced at all aluminum plants. During
the entire time the potliners are in the cell they absorb bath
materials. When a potliner fails, the aluminum and bath
materials are siphoned from the cell. The potliner is allowed to
cool, then is broken up, removed from the cell, and discarded.
Spent potliners consist of large chunks of carbon coated with
2-52
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bath materials. Spent potliners contain 35 to 51 percent carbon,
10 to 13 percent sodium, 8 to 10 percent fluoride, 5 to 6 percent
calcium, and 4 to 9 percent aluminum; they also contain small
amounts of minor bath components together with nitrides and
cyanides that are formed in the liner (2-22).
A study analyzed scrap potliners for potentially hazardous
constituents (Table 2-10) (2-23). The samples were also tested
to determine the leachability of the potentially hazardous
constituents. On the basis of the leachability tests, potliners
were labeled potentially hazardous; they are not included
however, in the preliminary list of hazardous materials published
in the Federal Register of December 18, 1978 (43 Fed. Reg. 58946)
(2-23).
Scrubber liquor from wet scrubbers contains dissolved
gaseous fluorides and some particulate matter. The scrubber
liquor is neutralized with hydrated lime, and the precipitated
solids are allowed to settle. The settled sludge contains
silt-sized particles of fluorspar (CaF2) cryolite (Na^AlF^),
alumina (Al(OH)3), and carbon. Typical composition of settled
sludge is 60 percent fluorspar, 25 percent aluminum as alumina
and aluminum fluoride, 10 percent cryolite, and 3 percent carbon.
Scrubber sludge was also tested for leachability and found
to be potentially hazardous, although it is not included on the
preliminary list of hazardous materials (Table 2-10) (2-23).
Scrap brick discarded at prebake plants has not been tested
for leachability, although it is doubtful that the brick absorbs
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TABLE 2-10
ANALYSIS FOR POTENTIALLY HAZARDOUS SOLID WASTES FROM THE
PRIMARY ALUMINUM SMELTING INDUSTRY*
Concentration of potentially hazardous constituents (ppm)
Waste type
Fluoride
Cyanide
Cu
Zn
Pb Cr Cd
Mn
Ni
Potlmers
44-186
58-1,050
Scrubber sludge
67
Shotblast dusts
0-26
1.5 x 104-5.6 x 105
320
40 620
Casthouse dusts
6,200
550
4,600 230
200
150
Cryolite recovery sludge
(black mud)
1.0-2.2
92.5
* U.S. Environmental Protection Agency. Assessment of Industrial Hazardous Waste
Practices in the Metal Smelting and Refining Industry. V. 4. Appendices SW-145c.4
Springfield, Va., National Technical Information Service 1977. 58 p.
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the fluorides and cyanides contained in recycled anode butts.
Scrap brick is composed of common refractory material and is
currently considered nonhazardous.
The remaining solid wastes from an aluminum plant are dusts
from shotblasting and from processing casthouse skims. Dusts
from shotblast used in cleaning anode butts and connecting rods
are composed of carbon, iron, copper, and bath materials
containing fluorides. The dusts were analyzed for potentially
hazardous components (Table 2-10) and leachability tests were
conducted (2-23). Although the shotblast dust has a high
concentration of copper, little was solubilized in the
leachability test (2-23). Shotblast dusts are considered
nonhazardous. Casthouse dusts collected during skims processing
contain aluminum and aluminum oxides along with fluoride or
chloride salts and significant quantities of heavy metals (Table
2-10). These dusts are not included in the preliminary list of
hazardous wastes.
A solid waste not yet mentioned, which is produced at
perhaps as few as one or two plants, is the "black mud" remaining
from cryolite recovery. This sludge contains mainly carbon and
unrecovered bath materials, but the exact composition is unknown.
This sludge also was analyzed for potentially hazardous
components (Table 2-10), and solubility tests were made (2-23).
This sludge is not included in the preliminary list of hazardous
wastes. Because EPA's preliminary list of hazardous wastes may
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be changed before it becomes final, the status of all aluminum
wastes could change in the future.
Solid Waste Control Practices and Costs
This section describes solid waste control practices and
their associated costs. The first portion deals with current
practices in the industry. The costs of solid waste disposal at
the model plants are developed on the basis of the most common
practices currently being used. The model plant costs are used
to determine current disposal cost factors, in dollars per ton of
product, which are applied in determining total industry costs
(capital and annual) for solid waste disposal. (Total industry
costs are the same as total national costs.)
The discussion then turns to alternative disposal practices,
which provide what are considered to be adequate environmental
safeguards for solid waste disposal. The costs that would be
expected under these alternative disposal practices are also
calculated for the model plants. These costs are then used, as
were current disposal costs, to develop cost factors and total
industry capital and annual costs of the alternative disposal
practices.
The final portion of this section is an analysis of the
costs of current and alternative solid waste disposal practices.
The costs are first compared to determine the incremental cost,
which is the additional cost incurred in implementing the
alternative control systems. Next, the incremental cost is
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separated into two components representing costs for disposal of
hazardous and nonhazardous wastes. The analysis further
determines the proportions of the increased costs that are
attributable to state solid waste regulations
(state-standard-induced costs) and to Criteria set forth in the
nonhazardous waste section (Section 4004) of the Resource
Conservation and Recovery Act (Criteria-induced costs). Finally,
the additional industry costs attributable to RCRA Criteria are
compared with other industry costs incurred by compliance with
air and water pollution control regulations.
Current Solid Waste Control Practices
Current solid waste control practices are similar throughout
the aluminum industry, with some variations. Typically each
plant has a land disposal area for potliners, and casthouse dusts
and, at prebake plants, shotblasting dusts and, spent brick from
the anode baking furnace. Plants that operate wet scrubbers
neutralize the scrubber liquor and allow the solids to settle in
lagoons. Settled solids are usually dredged from the lagoon and
discarded on land. Some plants, however, allow the lagoons to
fill to capacity and construct new lagoons as necessary.
Current efforts to determine the suitability of a site for
solid waste disposal are usually limited to locating an available
land area that is convenient to the plant. Site preparation
consists mostly of clearing trees and shrubs and grubbing the
areas. Current construction practices usually do not include
installation of soil sealants or liners to prevent seepage or
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percolation. Because monitoring wells are not common in the
industry, the degree to which potentially hazardous materials
escape from disposal sites is not known. Construction of
collection and diversion ditches to protect the land and surface
waters from runoff also is rare.
Current Control of Potliners*—Scrap potliners either are
removed from the pots in place in the potroom or the entire pot
is moved to a designated area for removal of the liner. The
potliner is temporarily stored close to the removal area until it
is transferred to the permanent disposal site.
The temporary storage areas are usually concrete pads with
side walls to contain runoff from the pile. A sump collects the
runoff and pumps it to the wastewater treatment plant, where it
is combined with other wastewater streams. Every 3 or 4 days the
accumulated potliners are removed and transported to the
permanent dump. Some plants temporarily store the spent
potliners directly on the ground until enough have accumulated to
justify transfer to the permanent disposal site, usually by a
dump truck.
In the past some plant operators temporarily stored scrap
potliners for 3 to 5 years until enough had accumulated to be
processed for cryolite recovery. Where plants have the
capability of recovering cryolite, this may still be done;
* Current control practices described here are not only for
scrap potliners but also for shotblast dusts, casthouse dusts and
scrap brick.
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however, the demand for cryolite has decreased in the past
several years, and at most plants the scrap potliners are now
disposed of at a permanent disposal site.
Scrap brick removed during furnace rebuilding is stored in a
temporary disposal area near the furnace building until a
sufficient quantity has accumulated to justify transfer to the
disposal site. The scrap brick is usually discarded in the same
dump as the scrap potliners but in a different section.
Shotblast dusts and casthouse dusts are temporarily stored
in hoppers beneath the air pollution control device in which they
are collected. The collected dusts are transported to the
permanent disposal site as necessary.
Permanent disposal sites currenty used by most aluminum
plants are open dumps near the main plant. No site preparation
other than tree and shrub removal is practiced. All of the
wastes are disposed of in the same dump, but they are segregated
to permit recovery should economics and available technology
permit recycling of these materials in the future.
Although the disposal methods described above are the most
common, there are deviations. At least one plant disposes of
spent potliners in an abandoned, lined lagoon that is filled to
capacity with scrubber water sludge. Also, a few plants are
known to store spent potliners on concrete pads in completely
enclosed buildings. The number of plants using this method and
the quantity of waste involved are not known. Recovery of
cryolite and carbon from spent potliners is also practiced at an
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unknown number of plants. This practice reduces, but does not
eliminate, the quantity of potliner waste going to land disposal
at these plants. In addition, a portion of the scrap brick
discarded at some plants is used as roadbed fill or other fill
near the plant site. The number of plants and the quantities of
brick involved are unknown.
Current Control of Sludge—Aluminum plants using wet air
pollution control devices, as represented by Model 2 plants,
discard sludges from treatment of the scrubber liquor. Solids
are partially settled in thickeners, and the resulting slurry is
then pumped to a lagoon for further settling. At most plants the
settled sludge is dredged from the lagoon onto a nearby land
disposal area. This practice permits the use of a ^single lagoon
for the life of the plant. Some plants, however, allow the
lagoons to fill to capacity and construct new lagoons as needed.
Most lagoons used by aluminum plants are unlined (although
at least one plant has clay-lined lagoons). The lagoon is
located near the main plant, and slurries are pumped to it. The
lagoon is dredged by use of a slurry pump, or a clamshell to
/
remove the settled sludge. Dredged sludges are allowed to dry in
an open dump. The sludge dump is unlined but is originally
excavated to a depth of 1.5 ft (0.5 m) to prevent excessive
runoff.
Costs of Current Controls
Current solid waste disposal costs are developed for the
model plants. The handling and disposal systems associated with
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the model plants represent the most common methods currently in
use in the primary aluminum industry. Temporary storage and
permanent disposal areas are sized to meet the disposal
requirements of the model plant. Temporary storage areas are
designed to provide storage for 1 week, and the permanent
disposal site is designed to provide disposal for a minimum of 20
years at the current solid waste generation rate. Capital costs
for each site include costs of land, construction, and equipment.
The method of amortization and all other important cost
methodologies are described in Appendix C.
Current Control Costs for Model 1—Costs of current solid
waste handling and disposal are developed in this section for the
Model 1 plant (Figure 2-2), which represents primary aluminum
facilities using dry air emission collection devices to control
off-gases from the electrolytic cells. All plants represented by
Model 1 are of the prebake type except for one HSS operation.
Since this one plant constitutes a small fraction of the
industry, it is assumed for this study that all Model 1 plants
are prebake operations.
The main sources of solid wastes produced at Model 1 plants
for which disposal costs have been developed are scrap potlinings
from electrolytic cells and scrap brick from anode baking
furnaces. Costs have also been developed for the handling and
disposal of dusts from anode butt cleaning; these dusts
constitute a relatively small amount of waste compared with
potlinings or scrap brick. Because most plants represented by
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Model 1 generate dust in processing casthouse skims the current
costs include the cost of handling and disposing of these dusts.
Current costs are not developed for the handling of residuals
from the control of off-gases from the anode baking furnace.
These gases usually are emitted directly to the atmosphere with
no controls; some are controlled by dry scrubbing, which does not
generate a solid waste. Although some facilities do control
these off-gases with wet scrubbers that generate a solid waste,
no costs are developed for disposal of this waste because it
occurs in only a small fraction of the industry and in very small
amounts.
The main components of the Model 1 disposal system are two
temporary storage areas and a single permanent disposal site. An
2 2
area of 4,000 ft (370 m ) located near the potrooms is devoted
to the temporary storage of scrap potliners. An area of equal
size located near the furnace building is used for temporary
storage of scrap furnace brick. The permanent disposal site,
covering 5 acres (2 ha) eventually receives all solid wastes
generated at the plant. Temporary storage sites for shotblast
dusts and casthouse dusts are not included because these dusts
are stored in hoppers beneath the collection device until
transported to the dump.
Construction costs include all work necessary to prepare the
solid waste storage and disposal systems. Specifically, the
costs include surveying, minimal site preparation, the concrete
pad for temporary potliner storage, and a haulage road for
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transport to the disposal site. Surveying and site preparation
are preliminary operations conducted at each site. The pad for
temporary potliner storage is constructed of concrete. It
collects runoff and prevents leaching from the scrap potliners
while they are-stored at that location. A gravel haul road 0.5
mile (0.8 km) long is built for transport of the waste to the
permanent disposal site.
Equipment for current solid waste control includes a pump,
installed piping, a dump truck, and a front-end loader. The pump
and pipe are used at the temporary potliner storage site to pump
collected runoff to a treatment facility.
Since the quantity of runoff from the concrete pad varies
with geographical location, no specific size is designated for
the sump pump that handles the runoff. Instead, a total cost of
$2,000 is assumed for the entire system including pump, motor,
installation materials, and installation labor. Also included is
the cost of 500 ft (150 m) of installed pipe to carry the water
from the pad to a treatment facility. The dump truck and
front-end loader are used to load and transport wastes to the
permanent disposal site. Because 20 percent of their time is
allocated to transporting wastes to the permanent disposal site,
20 percent of the capital cost is charged to the permanent
disposal site.
Annual expenses include the amortized costs of land,
construction, and equipment; operations and maintenance; taxes;
and insurance. Operations and maintenance costs include
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personnel, repair and maintenance, and fuel and electricity used
in operation of the solid waste handling system. Personnel costs
are based on the time required to transport the scrap potliners,
scrap brick, shotblast dusts, and casthouse dusts to the disposal
site. Approximately 12,200 tons (1.1 Gg) of wastes per year is
transported to the dump. This transport requires an average of 4
hours per day to operate both the front-end loader and truck. An
additional labor charge is made for a foreman's time to oversee
the transport. Hourly rates are listed in Appendix C. Repair
and maintenance costs are calculated from the percentages also
listed in Appendix C. Fuel costs are based on the number of
operating hours, the fuel consumption rate, and the unit"cost of
fuel. Fuel consumption rates and unit costs are included in
Appendix C. A yearly electricity cost of $50 is added for the
sump pump on the temporary storage pad.
The total capital and annual operating expenses for the
solid waste disposal system associated with the Model 1 plant are
$53,400 and $38,750 respectively (Table 2-11). Capital and
annual disposal cost factors for Model 1 are $0.34 and $0.24 per
ton of aluminum produced. The total industry capital cost for
solid waste disposal at all aluminum plants represented by Model
1 is $657,000. Total annual operating cost is $477,000.
Current Control Costs for Model 2—Costs of current solid
waste handling and disposal methods are developed in this section
for the Model 2 plant (Figure 2-3), which represents aluminum
facilities using wet air emission collection devices to control
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TABLE 2-11
TOTAL COST OF CURRENT CONTROLS FOR
MODEL 1: ALUMINUM PLANTS WITH DRY SCRUBBING
(1978 dollars)
Temporary
storage
Permanent*
disposal
Capital Cost
Land
Construction
Survey
Site preparation
Concrete pad
Haulage road
200
100
7, 200
4, 900
1, 900
1,000
15,600
Equipment
4,400
13,200
Subtotal
Contingency (10%)
11,900
1, 200
36,600
3,700
TOTAL CAPITAL COST
13,100
40,300
53,400
Annual Cost
Land
Construction
Equipment
Operation and maint nance
Personnel
Maintenance
Fuel and electricity
+
900
800
400
50
600
2,400
2, 200
25,800
1, 500
3,500
Taxes
Insurance
100
100
400
TOTAL ANNUAL COST
2, 250
36,500
38,750
* The permanent disposal area is used for disposal of pot-
liners, scrap brick, shotblast dusts, and casthouse dusts.
+ The annual land cost is less than $50 and is not included
in the annual expenses.
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off-gases from the electrolytic cells. About half the facilities
represented by Model 2 are prebake plants, and the other half are
Soderberg cell operations.
The main sources of solid waste associated with Model 2 for
which current disposal costs are developed include scrap
potliners, scrap furnace brick, shotblast dusts, and casthouse
dusts. Another major solid waste associated with Model 2 is the
sludge or scrubber liquor caused by wet scrubbing of the
electrolytic cell off gases.
Current disposal practices associated with Model 2 include
temporary storage and permenant disposal areas similar to those
described for Model 1. The Model 2 disposal system also includes
a surface impoundment for settling scrubber sludges and a
dredging system to remove the accumulated solids from the
impoundment and transport them to the permanent disposal.site.
Land requirements for the Model 2 disposal system are
greater than for Model 1 because additional land is needed for
the surface impoundment and for disposal of the dredged scrubber
sludges at the permanent disposal site. The scrubber sludges are
deposited for settling in a 4-acre (1.6 ha) surface impoundment.
Additional land needed for the impoundment facility includes land
occupied by the dike around the impoundment and a buffer zone
beyond the dike. The total land requirement for the impoundment
facility is 5.6 acres (2.3 ha).
Five acres (2 ha) of land is needed at the permanent
disposal site for deposition of scrap potliners, scrap brick,
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shotblast dusts, and casthouse dusts. Land needed for final
deposition of dredged scrubber sludges is 0.5 acre (0.2 ha) per
year, or 10 acres (4 ha) for the 20-year life of the disposal
site. Thus, the permanent disposal site requires a total area of
15 acres (6 ha), consisting of 10 acres (4 ha) for dredged
sludges and 5 acres (2 ha) for all other wastes.
As in Model 1, the scrap brick and scrap potliners from
Model 2 are deposited in separate temporary storage areas before
being transported to the final disposal site. Each storage area
occupies 4000 ft^ (370 m^).
Construction costs for the Model 2 plant are similar to
those for Model 1 except for the surface impoundment and some
additional work at the permanent disposal site. Construction
costs for the temporary storage areas are identical to those
developed for Model 1. Costs for the permanent disposal site
include those for survey, site preparation, haulage road, and
some excavation. Costs of the first three are identical to those
of Model 1. The portion of the permanent disposal site that
receives the dredged scrubber sludges must be excavated to a
depth of 1.5 ft (0.5 m) to prevent excessive runoff. The costs
include those of removing soil and placing it in a dike around
the area. Costs for further dike preparation (compaction or
grading) are not developed. Construction costs for the 4-acre
(1.6 ha) impoundment include costs of survey, site preparation,
and impoundment construction. Costs of the survey and site
preparation are developed the same as before. Surface
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impoundment construction includes excavation, dike forming, dike
compacting, and fine grading. Construction costs are detailed in
Appendix C.
Equipment costs for the Model 2 disposal system are the same
as those for Model 1 plus the cost of dredging equipment used at
the surface impoundment. The surface impoundment is dredged with
a 2-hp slurry pump to permit continued use of the impoundment for
settling of solids from sludge. In addition to the pump costs,
the dredging system equipment costs include 600 ft (180 m) of
installed pipe and 900 ft (275 m) of flexible pipe, used to carry
dredged solids to the permanent disposal area.
Operation and maintenance costs for Model 2 are similar to
those of Model 1. Costs of temporary storage are the same, and
costs of permanent storage differ only in the addition of costs
to repair and maintain the area required for final deposition of
dredged scrubber sludge. Costs of operating the surface
impoundment (not incurred at Model 1 plants) include operator
time for dredging, repair and maintenance of the impoundment and
dredging equipment, and electricity. The operator time required
for dredging the impoundment is estimated to average 5 hours per
3
day. This is based on an annual accumulation rate of 819,600 ft
3
(23,200 m ) of settled solids and a pumping rate of 60 gallons
(227 liters) per minute. Repair and maintenance costs are a
percentage of construction and equipment costs. Fuel and
electricity costs consist solely of the electricity used by the
pump during dredging operations.
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The total capital and annual operating expenses for the
solid waste disposal system associated with Model 2 are $151,400
and $73,600, respectively (Table 2-12). The respective capital
and annual cost factors for Model 2 as calculated from Table
2-12, are $1.00 and $0.49 per ton ($1.1 and 0.54 per Mg) of
aluminum produced. The total capital and annual costs incurred
for the portion of the primary aluminum industry represented by
Model 2 are $1,507,000 and $731,000 respectively.
Current Control Costs for Model 3—Costs of current solid
waste handling and disposal methods are developed in this section
for the Model 3 plant (Figure 2-4), which represents aluminum
facilities using both wet and dry air emission collection devices
to control cell off-gases. For the purpose of this study it is
assumed that half of the potlines at each plant are controlled by
wet scrubbing devices. Three of the five plants represented by
this model are prebake plants and the others are HSS operations.
The main sources of solid waste associated with Model 3 for
which current control costs are developed include scrap
potliners, scrap brick, and scrubber sludge. The current control
costs also include two minor sources of solid wastes, shotblast
dusts and casthouse dusts.
Current disposal practices associated with Model 3 include
temporary storage sites, permanent disposal sites, and a surface
impoundment.
The total land required for the Model 3 disposal system is
less than that for Model 2 because less scrubber sludge is
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TABLE 2-12
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 2: ALUMINUM PLANTS WITH WET SCRUBBING
(1978 dollars)
Temporary
storage
Permanent•
disposa1
Sludge
disposal
Capital Cost
Land
Construction
Survey
Site preparation
Concrete pad
Haulage road
Surface impoundment
Excavation
Equipment
Subtotal
Contingency (10%)
TOTAL CAPITAL COST
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and Electricity
Taxes
Insurance
TOTAL ANNUAL COST
200
100
7,200
4,400
11,900
1,200
13,100
+
900
800
400
50
100
2,250
14,60C
5,600
3, 00C
15,600
38,700
13,200
90,700
9,100
99,800
1, 900
8,100
2,400
25,800
2,900
3,500
400
1,000
46,000
5, 500
2,100
1,100
13,000
13,300
35,000
3,500
38,500 151,400
700
2,300
2,200
18,250
1,200
200
100
400
25,350 73,600
* The permanent disposal area is used for disposal of potliners,
scrap brick, shotblast dusts, casthouse dusts, and dredged sludge.
+ The annual land cost is less than $50 and is not included in
the annual expenses.
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generated. Additional land occupied by the impoundment dike and
a buffer zone around the area is included. The total land used
for the surface impoundment is 3.4 acres (1.4 ha). The land
required at the permanent site for disposal of spent potliners,
scrap brick, shotblast dusts, and casthouse dusts is 5 acres (2
ha). The final disposal of dredged sludge requires an additional
5 acres (2 ha), half of that required for Model 2 since only half
of the cells have wet scrubbers. The total land required for the
permanent disposal site is 10 acres (4 ha). As in Models 1 and 2
2 2
two temporary storage areas of 4,000 ft (370 m ) are used to
store scrap potliners and scrap brick until enough has
accumulated to warrant hauling them to the disposal site.
Construction costs are developed for Model 3 in the same
manner and with the same components as those for Model 2. The
costs are lower, however, because the disposal areas are smaller.
Equipment costs for Model 3 are identical to those of Model
2. Hauling of scrap potliners, scrap brick, shotblast dusts, and
casthouse dusts to the permanent disposal site requires the same
amount of time for the truck and front-end loader. The size of
the dredge pump and therefore the cost also remain unchanged.
Model 3 annual costs include amortized capital costs,
operation and maintenance, and taxes and insurance. Operation
and maintenance costs include those for personnel, repair and
maintenance, and fuel and utilities. Personnel costs for hauling
solid wastes to the permanent disposal site include an average of
4 hours per day, 2 hours each for the truck driver and the
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front-end loader operator. An average of 2.5 hours per day is
also needed to dredge the surface impoundment. The number of
dredge operating hours is half of those required for the Model 2
plant because less sludge is dredged by the same size equipment.
Repair and maintenance costs are calculated as a percentage of
the capital costs. Costs of fuel and electricity are calculated
from the number of operating hours, the fuel or electricity
consumption rate, and the unit cost.
The respective capital and annual cost factors calculated
from these data (Table 2-13) are $0.73 and $0.38 per ton ($0.80
and $0.42 per Mg) of aluminum produced. Total capital and annual
costs for this portion of the primary aluminum industry are
$783,000 and $411,000, respectively.
Total Cost of Current Controls—The total estimated capital
and annual costs of current controls are $2,947,000 and
$1,619,000 respectively (Table 2-14). Based on the total
industry production of 4,539,000 tons (4.12 Tg) (Table 2-1), the
estimated annual cost of solid waste disposal is $0.0002 per
pound ($0.0004 per kg) of aluminum produced. The estimated
annual current disposal cost, based on 451,000 tons (409 Gg) of
solid waste generated per year, is $3.60 per ton ($3.97 per Mg)
of solid waste.
Alternative Solid Waste Control Practices
This section proposes alternative methods of solid waste
disposal that are judged to provide sufficient environmental
safeguards. The disposal practices are designed to protect human
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TABLE 2-13
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 3: ALUMINUM PLANTS WITH BOTH WET AND DRY SCRUBBING
(1978 dollars)
Temporary
storage
Permanent*
disposal
Sludge
disposal
Cacital Cost
-
Land
Construction
Survey
Site preparation
Concrete pad
Haulage road
Surface impoundment
Excavation
200
100
7,200
9,700
3, 700
2, 000
15,600
19,400
2,800
1,100
600
6, 500
Equipment
4,400
13,200
13,300
Subtotal
Contingency (10%)
11,900
1,200
63,600
6,400
24,300
2,400
TOTAL CAPITAL COST
13,100
70,000
26,700
109.80C
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and electricity
+
900
800
400
50
1,200
5,200
2,400
25,800
2,200
3,500
400
1,100
2,200
9,100
900
100
Taxes
Insurance
100
200
700
100
300
TOTAL ANNUAL COST
2,250
41,200
14,200
57,650
' The permanent disposal area is used for disposal of potliners,
scrap brick, shotblast dusts, casthouse dusts, and dredged sludge.
+ The annual land expense is less than $50 and is not included
in the annual expense.
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TABLE 2-14
TOTAL COST OF CURRENT SOLID WASTE CONTROL FOR THE
PRIMARY ALUMINUM SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 657,000 477,000
Model 2 1,507,000 731,000
Model 3 783,000 411,000
Total 2,947,000 1,619,000
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health and eliminate potential contamination of air and water.
These practices consist of relatively intensive site selection,
extensive site preparation, ground sealing, a seepage collection
system, runoff collection and diversion ditches, wells for
monitoring of groundwater, flood dikes, fencing, closure of
disposal sites, and postclosure monitoring and maintenance. Such
control practices are rarely followed in current disposal
operations. A detailed site-specific analysis is needed to
determine which controls are appropriate at each site. For
example, collection of seepage may not be necessary where
groundwater levels are low or where natural soil formations limit
the possibility that seepage will reach groundwater. Important
constituents of the alternate control method that are common to
all situations are relatively intensive site selection,
groundwater monitoring, site closure, and postclosure monitoring
and maintenance.
The site selection process involves the following
considerations: topography; soil type, including the chemistry
and permeability of surface and underground soils; availability
of land for expansion; long-range land use; consideration of
environmentally sensitive areas; and aesthetics. A site
selection process of this scope will increase the disposal costs
but will minimize long-term adverse effects.
Groundwater monitoring in the alternative system is designed
to detect contamination resulting from solid waste disposal. The
system incorporates six monitoring wells within the plant
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boundaries. At least one of these is to be installed
hydraulically upgrade from the disposal site to collect
background data on groundwater quality. Two wells are installed
immediately adjacent to and hydraulically downgrade of the
disposal site. Two of the remaining three wells are installed
within the property line hydraulically downgrade of the disposal
site. The sixth well is situated wherever desired (within the
plant line) to monitor groundwater.
Closure of a disposal site at the end of its useful life is
required under recently proposed (hazardous waste) regulations
and will probably be required for disposal of both hazardous and
nonhazardous solid wastes. Site closure consists of covering the
solid wastes with soil and revegetating the soil cover to prevent
erosion. The bottom cover layer is a soil having low
permeability to minimize water seepage into the discarded waste;
the upper layer is topsoil capable of supporting indigenous
vegetation. To ensure that funds will be available at the time
of site closure, a trust fund is established before the site is
opened.
The proposed regulations also require postclosure monitoring
of groundwater and leachate and maintenance of the site for 20
years after closure. Monitoring of groundwater and leachate
involves periodic collection and analysis of samples front the
onsite wells and the seepage collection system. Postclosure site
maintenance consists primarily of maintaining the soil cover,
vegetation, monitoring wells, and security fencing. Again, a
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trust fund to provide the required capital is established before
the site is used for waste disposal.
Alternative Control of Potliners*—Alternative methods for
control of solid wastes from aluminum smelters (scrap potliners,
scrap furnace brick, shotblast dusts, and casthouse dusts)
primarily involve the permanent disposal site. Current practices
for temporary storage of potliners, shotblast dusts, and
casthouse dusts, as described earlier, already provide adequate
control.
A concrete pad like that currently used for potliner storage
is used in the alternative system for temporary storage of
furnace brick. The extent to which fluoride and cyanide,
introduced into the anode paste by recycling of anode butts,
contaminate the furnace brick and subsequently leach from the
scrap brick is unknown, although it is generally believed that
the fluoride compounds leave in the furnace off-gases.
Several additional practices are suggested for operation of
the permanent disposal site. First is more intensive site
preparation, which in addition to clearing and grubbing as is
currently done includes removing the top few inches of soil and
grading the site. A system of drainage tiles is installed under
the disposal area to collect any seepage from the site. The
seepage collection system also allows monitoring of the quantity
of collected seepage. An increase in the quantity of seepage
* Alternative control practices described here are not only
for scrap potliners but also for shotblast dusts, casthouse dusts
and scrap brick.
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could indicate a rupture in the ground seal. An impervious
soil-cement pad 6 in. (15 cm) thick is installed over the
drainage bed to prevent leachate from entering the ground.
Runoff from surrounding land areas is diverted around the site by
ditches on the upgradient side of the disposal area; runoff from
the site is collected by ditches on the downgradient side.
Collected runoff and seepage flow to a common sump from which
they are pumped for treatment. Most aluminum facilities
(estimated as 75 percent of the industry) will also need flood
diking around the disposal site to prevent solid waste from being
washed away during periods of flooding.
Alternative Control of Sludge—The alternative sludge
control practices include some of those already described, such
as more extensive site preparation and a seepage collection
system under the surface impoundment. Site selection and
groundwater monitoring are done for the entire plant, and
therefore includes the surface impoundment. Closure and
postclosure maintenance are not applied to the surface
impoundment because it is dredged and remains usable for the life
of the facility. The alternative sludge control system consists
of lining the surface impoundment with a synthetic liner 30 mil
thick. The liner is covered with 0.5 yd (0.46 m) of protective
soil.
Costs of Alternative Controls
Costs of alternative solid waste controls are developed for
the model plants. All processes at all three model plants as
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well as the size of the temporary storage area, permanent
disposal site, and the surface impoundment are identical to those
used to develop the current control costs. Overall land
requirements are greater because additional land is required for
some of the control systems. Capital costs in the alternative
system include land, construction, and equipment as well as site
selection, closure, and postclosure maintenance. Annual costs
are calculated by amortizing capital costs and including
operations and maintenance costs.
Alternative Control Costs for Model 1—Alternative solid
waste disposal costs are developed in this section for the Model
1 plant and all plants it represents. No process modifications
are suggested, and all solid wastes that are generated and
discarded in the current control system are generated and
discarded in the alternative system. The main components of the
disposal system are still the two temporary storage locations and
the permanent disposal site.
Alternative solid waste disposal starts with site selection.
In the alternative system one engineer a year is allotted for
study of topography, soil conditions and type, and hydrological
conditions. First a general topographical survey of the area is
performed to locate a few potential sites, at which more
extensive soil and hydrogeological testing is done. After
completion of all tests, the engineering report is used as a
basis for final site selection.
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Land requirements in the alternative control system include
temporary storage sites and the permanent disposal area. The two
temporary storage sites, one each for scrap potliners and scrap
brick, are identical in area to those in the current control
2 2
systems, 4,000 ft (370 m ). The other land area for disposal is
the permanent disposal site for scrap potliners, scrap brick,
shotblast dusts, and casthouse dusts. The land area required for
solid waste disposal is 5 acres (2 ha), the same as the current
disposal area; however, an additional 20 percent of the required
land area is added for alternative controls. The additional area
provides a buffer area around the disposal site and permits
installation of ditching and a sump on the perimeter of the site.
The total land area then becomes 6 acres (2.43 ha).
Construction costs include all work required to prepare the
solid waste storage and disposal system. The alternative control
costs include all items in current control costs — survey, site
preparation, concrete pads, and haulage road; they also include a
ground seal in the disposal area, a seepage collection system,
runoff collection and diversion ditches, a flood dike, fencing,
and monitoring wells. Surveying and site preparation are
conducted at all sites in a manner identical to those of current
controls except that site preparation includes grading and
topsoil removal. The alternative controls includes the
installation of 6-in.- (15-cm-) thick concrete pads at both
temporary storage sites. The concrete pads collect runoff and
prevent leaching from the scrap materials during temporary
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storage. Waste is transported1 from the plant site to the
disposal area on a 0.5- mile (0.8-km) gravel haulage road
constructed for that purpose. Potential contamination of
ground-and surface water from the solid wastes at the permanent
disposal site are minimized by several items constructed at the
site. First a seepage collection system consisting of 4-in. -
(10-cm-) diameter perforated drain pipes is installed under the
disposal site. Collected seepage flows to a sump, from which it
is pumped to a treatment facility. To prevent leachate from
entering the ground, a soil cement pad 6 in. (15 cm) thick is
installed over all 5 acres (2 ha) of the disposal site. Runoff
from the pad is collected in ditches. Collected runoff flows to
the same sump as the collected seepage and is pumped to the same
treatment facility. Disposal sites located in flood plains that
could be inundated by a 100-year flood are protected by a 6-ft
(2-m) tall flood dike. It is estimated that 75 percent of all
aluminum plants will require flood dikes around the permanent
disposal site. Finally a 6-ft (2-m) woven wire fence is con-
structed around the entire site, including the flood dike, to
prevent unauthorized access to the area. The groundwater is
monitored at six wells within the plant boundary to detect any
contaminants that may have leached from the disposal site.
The equipment used in the alternative control system is
identical to that in current use except that an additional pump
and length of pipe are needed for the concrete pad at the scrap
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brick temporary storage area to pump accumulated water from the
sump. The pump and piping costs are assumed equal to those at
the potliner temporary storage site.
Closure of the disposal site at the end of its useful life
involves covering the waste with soil and revegetating the area.
Costs of site closure include those for excavation and placement
of a 2-ft (0.6-m) soil cover on the solid waste pile. The bottom
6-in. (15-cm) of soil are compacted to reduce the soil's
permeability and limit the seepage of water. The soil cover is
fine graded and finally revegetated. No costs are included for
regrading the waste pile to give it a gentle slope and reduce the
chance of erosion; it is assumed that during disposal the wastes
are dumped so that regrading is not necessary. The availability
of funds for site closure is assured by depositing in a trust
fund the amount needed for closure less the interest that will
accrue.
The most significant cost of the alternative disposal system
is for postclosure monitoring and maintenance. Monitoring, which
includes sampling and analysis of groundwater and leachate, is
continued for 20 years after site closure. Maintenance for the
groundwater monitoring wells, the drain system under the site,
the soil cover, vegetation, and the fence surrounding the site is
also provided for 20 years after closure. As with closure, the
funds needed for postclosure operations are placed in a trust
fund before the disposal site is used.
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Annual costs for the alternative disposal site include
amortized capital costs, operation and maintenance costs, taxes,
and insurance.
Annual operation and maintenance costs at the disposal site
are similar to those calculated for the current disposal system.
Personnel costs are the same. Repair and maintenance costs are
calculated as percentages of the construction and equipment costs
(Appendix C). Costs of fuel and electricity at the temporary
storage sites are doubled because of the second pump at the scrap
furnace brick temporary storage site. Costs of fuel and
electricity for the permanent disposal site are increased by 15
percent to include the electricity used by the sump pump and
additional fuel consumed because of more careful handling of the
solid wastes. Costs attributable to sampling and analysis
include the cost of sample collection, analysis, and well
maintenance.
The total capital and annual costs for the Model 1 solid
waste disposal system, including diking costs, are $620,300 and
$139,000 respectively (Table 2-15). The capital and annual cost
factors calculated from these data are $3.90 and $0.88 per ton
($4.30 and $0.97 per Mg) of aluminum produced. These cost
factors are used to calculate total alternative solid waste
control costs at those plants where diking will be needed to
protect the sites from flood waters. (It is assumed that 75
percent of the industry will require diking.) The total capital
and annual costs for the Model 1 aluminum plant, excluding diking
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TABLE 2-15
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 1: ALUMINUM PLANTS WITH DRY SCRUBBING
(1978 dollars)
Temporary
storage
Permanent'
disposal
Capital Cost
Site selection
Land
Construction
Survey
Site preparation
Concrete pad
Haulage road
Soil cement pad
Drain system
Ditching
Flood dike+
Fencing
Monitoring wells
Equipment
Closure operations
Postclosure operations
Subtotal
Contingency (15%)
TOTAL CAPITAL COST
Annual Cost
Site selection
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and electricity
Sampling and analysis
Closure operations
Postclosure operations
Taxes
Insurance
TOTAL ANNUAL COST
200
100
14,400
8,800
23,500
3,500
27,000
1,900
1,600
1,300
100
300
5,200
59,800
5,800
2,300
3,200
15,600
41,100
9,700
6,100
39,900
27,500
16,500
15,200
36,900
236,300
515,900
77,400
593,300 620,300
8, 000
800
21,800
2,800
25,800
8,000
4 , 000
20,000
5,000
31,800
200
5,900
134,100 139,300
* The permanent disposal area is used for disposal of pot-
liners, scrap brick, shotblast dusts, and casthouse dusts.
^ It is assumed that only 75 percent of all aluminum plants
will require flood dikes.
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costs, are $547,700 and $132,500, yielding capital and annual
cost factors of $3.61 and $0.83 per ton ($3.98 and $0.91 per Mg)
aluminum produced, respectively. These costs are applied to the
25 percent of the industry where no diking is needed. The total
capital cost for the alternative solid waste disposal system at
all plants represented by Model 1 is $7,479,000. Total annual
costs of operating the alternative system at all plants
represented by Model 1 is $1,689,000.
Alternative Control Costs for Model 2—Alternative solid
waste control costs are developed in this section for the Model 2
plant and all facilities it represents. No process modifications
for the alternative controls are suggested, and all solid wastes
generated and discarded in the current control system are
generated and discarded in the alternative system. The
alternative solid waste disposal system for the Model 2 plant is
identical to that for the Model 1 plant with the addition of a
surface impoundment to settle scrubber sludges.
Several costs developed for the Model 1 plant are similar to
the corresponding costs developed for Model 2. The costs of site
selection and the capital and annual costs of the temporary
storage areas are identical. Also, costs of land for the
permanent disposal site, construction, equipment, closure, and
postclosure are developed as described for Model 1, although the
actual cost is greater for Model 2 because the permanent disposal
site is larger than that of Model 1. Model 2 plant costs also
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include the cost of the surface impoundment in which the sludges
are allowed to settle.
The basic land requirements for the Model 2 alternative
control system are identical to those of the current Model 2
system: 15 acres (6.1 ha) for the permanent disposal site, 5
acres (2 ha) for the potliners, 10 acres (4 ha) for sludge
disposal, and 5.6 acres (2.3 ha) for the surface impoundment.
For the alternative system total this area is increased by 20
percent to provide room for the seepage collection system, the
runoff collection ditches, and the sump. Thus the land areas
costed under the alternative system are 18 acres (7.3 ha) for the
permanent disposal site and 6.8 acres (2.8 ha) for the surface
impoundment.
Costs for construction of the permanent disposal site are
developed in the same manner as those of Model 1. The Model 2
costs also include those for construction of the surface
impoundment, that is, the costs of the survey, site preparation,
impoundment formation, liner, liner protecting soil cover, and
the seepage collection system. Costs of surveying and site
preparation are described earlier. A seepage collection system
is installed under the surface impoundment site. The surface
impoundment is then constructed and lined with a synthetic liner
to prevent seepage. Impoundment construction costs are identical
to those described for Model 2 current control. Since the
impoundment will be dredged, a 18-in. (0.5-m) soil cover is
placed over the liner to protect it during dredging.
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Model 2 equipment costs are identical to those for Model 1
except for two additional items, both associated with the surface
impoundment dredging operations. A 2-horsepower slurry pump is
used to remove the settled solids from the impoundment. The
dredged slurry is pumped through a 3-in (7.6-cm) pipe to the
disposal site. Pipe costs include 600 ft (180 m) of installed
pipe and 900 ft (275 m) of flexible pipe.
Annual operating costs are developed in the same manner as
those for Model 1. Annual costs for the temporary storage sites
are identical to those of Model 1 and costs for the permanent
disposal site are similar; the higher cost of operating Model 2
result from the larger size of the disposal area. Annual costs
of the surface impoundment include annualized capital costs,
operating and maintenance costs, taxes, and insurance. Operating
and maintenance costs include the following: personnel for
dredging operations (5 man-hours per day); repair and maintenance
costs calculated as a percentage of capital costs; fuel and
electricity, which is limited to the electricity used during
dredging; and groundwater sampling and analysis.
The total capital and annual costs of alternative solid
waste control for Model 2, including diking costs, are $134,300
and $241,700, respectively (Table 2-16). The capital and annual
cost factors for Model 2 are $7.51 and $1.60 per ton ($8.28 and
$1.76 per Mg) of aluminum produced. At plants that need no flood
diking the capital and annual cost factors are $7.02 and $1.53
per ton ($7.74 and $1.69 per Mg) of aluminum produced. The total
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TABLE 2-16
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 2: ALUMINUM PLANTS WITH NET SCRUBBING
(1978 dollars)
Temporary
Permanent*
Sludge
storage
disposal
disposal
Capital Cost
Site selection
59,800
Land
200
17,600
6, 600
Construction
Survey
100
6,800
2, 600
Site preparation
9, 500
3, 600
Concrete pad
14,400
Haulage road
15,600
Solid cement pad
123,400
Surface impoundment
13,000
Liner
81,100
Soil cover
39,500
Drain system
28,800
10,400
Ditching
11,600
Flood dike-
64,300
Fencing
53,700
Monitoring wells+
16,500
Equipment
8,800
15,200
15,300
Closure operations
109,500
Postclosure operations
258,500
Subtotal
23,500
790,800
172,100
Contingency (15%)
3,500
118,600
25,800
TOTAL CAPITAL COST
27,000
909,400
197,900 1,134,300
Annual Cost
Site selection"5"
8,000
Land
2,400
900
Construction
1, 900
44,400
20,200
Equipment
1,600
2,800
2, 900
Operation and maintenance
Personnel
25,800
18,300
Maintenance
1, 300
16,500
8, 900
Fuel and electricity
100
4,000
200
Sampling and analysis^
20,000
Closure operations
14,700
Postclosure operations
34,800
Taxes
400
200
Insurance
300
9,100
2,000
TOTAL ANNUAL COST
5,200
182,900
53,600 241,700
* The permanent disposal area is used for disposal of pot-
liners, scrap brick, shotblast dusts, casthouse dusts, and dredged
sludge.
+ These costs are included only in the permanent disposal
site costs; however, they are total plant costs that apply to all
storage and disposal sites.
§
It is assumed that only 75 percent of all aluminum plants
will require flood dikes.
2-88
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capital cost for all plants represented by Model 2 is estimated
at $11,096,000. Total annual cost is estimated at $2,376,900.
Alternative Control Costs for Model 3—Costs of alternative
solid waste controls are developed in this section for the Model
3 plant and all facilities it represents. The alternative solid
waste control system is identical to the system described for
Model 2 except that the surface impoundment is smaller because
less sludge is being generated.
Costs are developed by adjusting the Model 2 plant costs to
account for the smaller surface impoundment, as was done in
calculating the current control costs. Land costs are reduced
because less scrubber sludge is settled and dredged than at the
Model 2 plant. Land requirements are reduced to 12 acres (4.9
ha) for the permanent disposal site and 3.4 acres (1.4 ha) for
the surface impoundment. Construction costs include the same
components, but the values are lower because the permanent
disposal site and the surface impoundment are smaller. Equipment
costs are identical to those for the Model 2 plant because no
adjustment is made in the size of the dredging system.
Annual costs include amortized capital costs, operating and
maintenance costs, taxes, and insurance. Operating and
maintenance costs are approximately half of the Model 2 costs
because of the lower amount of sludge that is dredged. The
sludge quantity is half of that generated at the Model 2 plant,
but since the capacity of dredging equipment is not reduced only
half the time is required for pumping. The shorter dredging time
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reduces the costs of personnel and of fuel and electricity.
Repair and maintenance costs are calculated as a percentage of
the capital costs.
Capital and annual costs for the Model 3 alternative waste
control system, including flood diking, are $900,500 and $193,600
(Table 2-17). Capital and annual cost factors for this plant are
$5.96 and $1.28 per ton ($6.57 and $1.41 per Mg) of aluminum
produced respectively. At plants that need no flood diking the
capital and annual costs are reduced to $5.55 and $1.22 per ton
($6.11 and $1.34 per Mg) of aluminum produced. The total capital
cost of the alternative system at the five plants represented by
Model 3 is $6,306,000, and total annual operating cost is
$1,361,800.
Total Cost of Alternative Controls—The total estimated
capital and annual costs to the aluminum industry of implementing
the alternative solid waste control system are $24,881,000 and
$5,427,700 respectively (Table 2-18). Based on the total
aluminum industry annual production of 4,539,000 tons (4.1 Tg)
(Table 2-1), the estimated annual cost of alternative solid waste
disposal practices is $0.0006 per pound ($0.0013 per kg) of
aluminum produced. The estimated annual cost of alternative
disposal based on generation of 451,000 tons (409 Gg) of solid
waste per year is $12.03 per ton ($13.26 per Mg) of solid waste.
Cost of Closing Existing Solid Waste Control Sites
All aluminum plants currently have onsite areas for solid
waste disposal. These disposal sites contain some or all of the
2-90
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TABLE 2-17
TOTAL COST OF ALTERNATIVE SOLID WASTE DISPOSAL CONTROLS FOR
MODEL 3: ALUMINUM PLANTS WITH BOTH WET AND DRY SCRUBBING
(1978 dollars)
Temporary
storage
Permanent
disposal
Sludge
disposal
Capital Cost
Site selection"1
59,800
Land
200
11,600
3,300
Construction
Survey
100
4,500
1, 300
Site preparation
6,400
1,800
Concrete pad
14,400
Haulage road
15,600
Soil cement pad
82,300
Surface impoundment
6, 500
Liner
40,600
Soil cover
19,800
Drain system
19,400
5, 200
Ditching
9, 000
Flood dike5
53,600
Fencing
45,000
Monitoring wells"1'
16,500
Equipment
8, 800
15,200
15,300
Closure operations
72,700
Postclosure operations
254,100
Subtotal
23,500
665,700
93,800
Contingency (15%)
3,500
99,900
14,100
TOTAL CAPITAL COST
27,000
765,600
107,900
900,500
Annual Cost
Site selection"1"
8,000
Land
1,600
400
Construction
1,900
33,900
10,100
Equipment
1,600
2,800
2, 900
Operation and maintenance
Personnel
25,800
9,100
Repair and maintenance
1, 300
12,600
4,900
Fuel and electricity
100
4,000
100
Sampling and analysis"1"
20,000
Closure operations
9, 800
Postclosure operations
34,200
Taxes
300
100
Insurance
300
6,700
1, 100
TOTAL ANNUAL COST
5,200
159,700
28,700
193,600
* The permanent disposal area is used for disposal of pot-
liners, scrap brick, shotblast dusts, casthouse dusts, and dredged
sludge.
* These costs are included only in the permanent di posal
site costs; however, they are total plant costs that apply to all
storage and disposal sites.
5 It is assumed that only 75 percent of all aluminum plants
will require flood dikes.
2-91
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TABLE 2-18
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR THE
PRIMARY ALUMINUM SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 7,479,000 1,689,000
Model 2 11,096,000 2,376,900
Model 3 6,306,000 1,361,800
Total 24,881,000 5,427,700
2-92
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solid wastes described earlier, depending on the cell type and
air pollution control devices used at the plants over past years.
The current and past practices for solid waste control at these
disposal sites may not provide adequate protection of human
health and the environment according to RCRA standards;
therefore, these sites may be declared open dumps, and operators
will be required to close or upgrade them.
For this study it is assumed that all existing onsite
disposal areas fail to meet RCRA criteria, that these sites will
be closed rather than upgraded to meet RCRA requirements, and
that new onsite disposal facilities that comply with RCRA
standards will be constructed. The costs of closure for existing
sites are estimated to determine the potential capital and annual
cost that may eventually be incurred by the aluminum industry.
Calculation of the closure costs requires some estimate of
the volume of solid waste accumulated to date. Because it was
not possible to calculate the accumulated solid waste at each
plant, the model plants were used to generate estimates. The
following assumptions were made:
° Processes currently used at the model plant have been
used since the plant opened.
° The current solid waste generation factors have re-
mained unchanged since the plant opened.
° Since most plants increase capacity and production
during plant life, the long-term production is assumed
to be 1/2 of current production.
° Age of the model plant is the average of the ages of
all plants represented by the model.
2-93
-------
With these assumptions and the known solid waste densities,
the volume of solid waste accumulated on site can be calculated
and the closure costs determined.
Closure of an existing solid waste disposal area is similar
to closure of an alternative site at the end of its useful life.
A 2-ft (0.60-m) soil cover is placed over the solid waste. The
bottom 6 in. (15 cm) of soil cover is compacted to reduce
permeability, and the top 18 in. (45 cm) must be capable of
supporting indigenous vegetation. The top 6 in. (15 cm) of soil
must be topsoil. The soil cover is then revegetated to prevent
erosion.
These closure costs do not include the cost of grading the
waste to meet gradient requirements or the cost of postclosure
monitoring and maintenance. A grading cost is not included
because the grades of existing waste piles are unknown and no
reasonable estimate of the solid waste quantity needing grading
could be made. Costs of postclosure monitoring and maintenance
are not included for two reasons. First, both the alternative
and the existing disposal facilities are on the plant site, and
the groundwater monitoring established at the alternative
disposal site also satisfies the monitoring requirements of the
closed existing site. Second, it is assumed that ground mainte-
nance practices are sufficient to maintain the soil and plant
cover of the closed site.
The total capital and annual costs to the aluminum industry
for closure of existing solid waste disposal facilities are
2-94
-------
$1,678,600 and $225,800 (Table 2-19). Annual costs are
calculated by amortizing capital costs for 20 years and applying
a 15 percent contingency factor.
Analysis of Solid Waste Control Costs
The cost analysis presented here includes a calculation of
the total incremental costs that would be incurred by the
aluminum smelting industry through implementation of alternative
solid waste control practices and closure of existing
(accumulated-to-date) disposal sites (Table 2-20). The total
incremental cost is attributed exclusively to nonhazardous wastes
because none of the solid wastes associated with primary aluminum
smelters appears in EPA's hazardous waste list.
The fraction of the incremental cost of nonhazardous solid
waste control that can be attributed to the RCRA nonhazardous
waste criteria is estimated by grouping the total incremental
costs into two categories: state-standard-induced costs (cost of
complying with current State regulations) and Criteria-induced
costs (cost of complying with RCRA criteria that are more
stringent than current state regulations). Provisions of the
various state regulations were determined by consulting an
analysis of state regulations and the proposed Federal Criteria
(2-24). The major costs to the aluminum industry that could be
potentially attributable to the RCRA Criteria would derive from
four criteria, those dealing with environmentally sensitive areas
(flood plains), surface water, groundwater, and safety (access).
Costs entailed in closure of existing and alternative control
2-95
-------
TABLE 2-19
TOTAL COST OF CLOSING EXISTING SOLID WASTE CONTROL SITES
FOR THE PRIMARY ALUMINUM SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 460,800 62,000
Model 2 659,500 88,700
Model 3 558,300 75,100
Total 1,678,600 225,800
2-96
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TABLE 2-20
CURRENT, ALTERNATIVE, CLOSURE, AND INCREMENTAL CONTROL COSTS FOR
THE PRIMARY ALUMINUM SMELTING INDUSTRY
(1978 dollars)
Current Alternative1 Closure^ Incremental^1
Waste type* Capital Annual Capital Annual Capital Annual Capital Annual
Nonhazardous 2,947,000 1,619,000 24,881,000 5,576,000 1,678,600 225,800 23,612,600 4,182,800
Hazardous 0 0 0 0 0 0 0 0
Total 2,947,000 1,619,000 24,881,000 5,576,000 1,678,600 225,800 23,612,600 4,182,800
* Solid wastes produced at aluminum plants currently are not included in the preliminary list of
NJ hazardous wasts according to the December 18, 1978 Federal Register (43 Fed. Reg. 58946). Therefore
vo
there are no costs for hazardous waste disposal.
^ Alternative control costs include the cost of the alternative controls together with the cost of
closing and maintaining the alternative disposal sites.
§
Closure costs represent the cost of closing existing solid waste disposal sites.
' Incremental costs equal the sum of the cost of alternative controls and costs of closure minus the
costs of current controls.
Note: Metric conversion table is given in front matter.
-------
facilities and in postclosure maintenance of the alternative
facilities cannot be directly attributed to any one criterion but
are indirectly attributed to all criteria. For purposes of this
study all closure costs are assumed to be attributable to the
Criteria. Other Criteria (those dealing with wetlands,
permafrost, critical habitats, sole-source aquifers, air, disease
vectors, explosive gases, fires, toxic gases, and bird hazards)
are considered to be inapplicable to the primary aluminum
industry.
In most states with aluminum plants the existing state
regulations contain requirements that satisfy the four RCRA
criteria of interest (flood plain, surface water, groundwater,
and access). Criteria for surface and groundwaters are met in
all but one state. Three states have no safety regulations
applying to access, and six states have no flood-plain
regulations as stringent as RCRA criteria. The Criteria-induced
costs (Table 2-20) therefore consist of those that are
attributable to: (1) closure of nonhazardous existing solid
wastes facilities; (2) closure and postclosure monitoring and
maintenance of the alternative nonhazardous wastes facilities;
and, (3) alternative control techniques to protect flood plains,
surface waters, groundwaters and access, where regulations are
insufficient to meet these RCRA Criteria.
The incremental cost of Criteria-induced nonhazardous waste
control in the aluminum smelting industry is $1,328,500 (Table
2-21), which represents 32 percent of the total incremental cost
(for controlling nonhazardous wastes) on an annual basis.
2-98
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TABLE 2-21
CRITERIA-INDUCED CONTROL COSTS FOR THE PRIMARY ALUMINUM
SMELTING INDUSTRY*
(1978 dollars)
State
Capital
Annual
Alabama
1,220,900
151,700
Arkansas
464,300
54,000
Indiana
726,000
90,400
Kentucky
856,100
53,300
Louisiana
1,027,700
131,000
Maryland
361,800
42,400
Missouri
287,000
33,600
Montana
546,400
63,900
New York
854,300
100,000
North Carolina
368,500
43,200
Ohio
980,500
109,400
Oregon
670,600
78,500
Washington
2,885,300
337,900
West Virginia
335,000
39,200
Total
11,512,400
1,328,500
* These values include additional costs for closure
of accumulated nonhazardous solid waste, closure and
postclosure maintenance of alternative nonhazardous
solid waste systems and Criteria-induced costs for
states whose solid waste regulations do not satisfy
the Criteria.
2-99
-------
For purposes of comparison, the total cost that has been
incurred by the aluminum industry to meet air quality regulations
has been estimated to be $15.84 per ton ($17.46 per Mg) of
aluminum produced) (2-25). This value is in 1970 dollars and
represents an industry-wide average annual costs for a variety of
different types of air pollution control devices utilized by
industry. The cost is approximately 13 times greater than the
incremental annual cost of solid waste control as calculated in
this study; that is, $1.20 per ton ($1.32 per Mg) of aluminum.
Costs of water pollution control vary widely, and valid
comparisons are difficult. Estimates show that aluminum smelters
required to implement the best practicable control technology
currently available to comply with the July 1, 1977, water
pollution discharge limits would incure an additional operating
cost of $4.20 per ton ($4.6 per Mg) of aluminum produced (2-10).
It is also estimated that an additional increase in operating
cost of $1.00 per ton ($1.13 per Mg) would be incurred in
complying with the July 1, 1983, limits (2-10). Together the
costs of water pollution control are about 4 times greater than
the total incremental costs of solid waste control. On the basis
of these estimates it appears that implementation of the
alternative solid waste control systems to meet RCRA Criteria for
nonhazardous wastes would be significantly less expensive than
implementation of either air or water control regulations.
2-100
-------
REFERENCES FOR SECTION 2
2-1. Commodity data summaries 1977. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1977.
2-2. Nonferrous metal data 1975. American Bureau of Metal
Statistics, Inc., New York, 1976.
2-3. Personal communication, H. Kurtz, Bureau of Mines to D.
Sass, PEDCo. November 1978.
2-4. Bauxite and alumina in the second quarter of 1977. Mineral
Industry Surveys. U.S. Department of the Interior,
Bureau of Mines, Washington, D.C., September 9, 1977.
2-5. Patterson, S.H., and J.R. Dyni. Aluminum and bauxite.
In: United States mineral resources. Brobst and
Pratt, Eds. Geological Survey Professional Paper 820.
U.S. Department of the Interior, Washington, D.C.,
1973.
2-6. Aluminum industry in June 1977. Mineral Industry Surveys.
U.S. Department of the Interior, Bureau of Mines,
Washington, D.C., September 28, 1977.
2-7. Aluminum mineral commodity profiles, MCP-14. U.S.
Department of the Interior, Bureau of Mines, Washington.
D.C. May 1978.
2-8. Primary aluminum plants, worldwide. Part one. U.S.
Department of the Interior, Bureau of Mines, Denver.
August 1977.
2-9. Stamper, J.W. Aluminum. In: Mineral facts and
problems. U.S. Department of the Interior, Bureau of
Mines, Washington, D.C. 1970.
2-10. Development document for effluent limitations guidelines
and new source performance standards for the primary
aluminum smelting subcategory of the aluminum segment of
the nonferrous metals manufacturing point source
category. EPA-440/l-74-019d. U.S. Environmental
Protection Agency, Washington, D.C., March 1974.
2-101
-------
2-11. Environmental assessment of the domestic primary aluminum
industry. (Preliminary draft). EPA Contract Nos.
68-02-2535, Task 1, and 68-03-2537, Task 1. PEDCo
Environmental, Inc., Cincinnati, Ohio. June 1978.
115 p.
2-12. Environmental considerations of selected energy conserving
manufacturing process options: Vol. VIII.
Alumina/Aluminum Industry Report. EPA-600/7-76-034th.
December 1976.
2-13. Annual survey of manufacturers of fuels and electricity
consumption. U.S. Department of Commerce, Bureau of the
Census, Washington, D.C., 1974.
2-14. Battelle Columbus Laboratories, Columbus, Ohio. Energy
use patterns in metallurgical and nonmetallic mineral
processing (phase 4 - energy data flowsheets, high
priority commodities) U.S. Department of the Interior,
Bureau of Mines, Open File Report 80-75. 1975. 192 pp.
2-15. Primary aluminum. In: The fabric filter manual.
C. Billings, ed. Mcllvaine Publishing Company, Inc.
August 1977.
2-16. Stamper, J.W., and C.M. Monroe. Aluminum. in: minerals
yearbook 1974. U.S. Department of the Interior,
Bureau of Mines, Washington, D.C.
2-17. Pacific Northwest aluminum producers face steep cost
increases for power. Engineering and Mining Journal.
V179 (10) October 1978.
2-18. Energy penalty of the nonferrous metals industry. Part
II: Primary smelting of aluminum (Draft). Prepared by
Arthur D. Little, Inc., for U.S. Environmental
Protection Agency. EPA Contract No. 68-01-4381, Work
Area No. II, August 1977.
2-19. Aluminum headed for a very solid year. Chemical and
Engineering News. 53(39):14-15. September 25, 1975.
2-20. Personal communication, J.W. Stamper, Bureau of Mines to
D. Sass, PEDCo. November 1978.
2-21. New processes promise lower cost aluminum. Chemical and
Engineering News. 51(9):11-12, February 26, 1973.
2-102
-------
2-22.
2-23.
2-24.
2-25.
2-103
Balgord, W.D. Recycling of potlining in the primary
aluminum industry: opportunities for technological
improvements. Presented at the Sixth Mineral Waste
Utilization Symposium Chicago, Illinois, May 3, 1978.
33 p.
U.S. Environmental Protection Agency. Assessment of
industrial hazardous waste practices in the metal
smelting and refining industry". V.2. Primary arid
secondary nonferrous smelting and refining. SW-145c.2.
Springfield, VA. National Technical Information Service,
1977. 244 p.
SCS Engineers. Comprehensive sludge study relevant to
Section 8002(g) of the Resource Conservation and Recovery
Act of 1976 (PL 94-580). Contract No. 68-01-3945, Long
Beach. 577 p.
U.S. Environmental Protection Agency. Air Pollution
control in the primary aluminum industry, V.l. Sections
1 through 10. Singmeister and Breyer, New York. EPA
450/3-73-004A, CPA 7021. July 23, 1973.
-------
SECTION 3
COPPER INDUSTRY
Industry Characterization
The domestic primary copper industry is faced with a number
of problems, including low prices, high labor and energy costs,
large inventories, and environmental requirements. In 1977 the
United States led the copper-producing nations in both production
and consumption. It is estimated that domestic reserves will
meet the demand up to the year 2000 (3-1).
The domestic primary copper industry consists of mining,
concentration, smelting, and refining segments. Generally, ore
is mined and concentrated at one location and then shipped to
nearby smelters for production of copper metal by
pyrometallurgical processes. These processes include roasting to
reduce sulfur content; smelting to remove most of the iron and
some other impurities; converting to reduce the matte to crude
blister copper; and fire refining or electrolytic refining to
remove impurities and to adjust the sulfur and oxygen levels
before casting.
Industry Description
Raw Materials—Copper concentrates produced by the
benificiation of various copper-containing ores are the main
3-1
-------
input material for production of primary copper. Three types of
smelters receive copper concentrates: integrated, custom, and
toll. An integrated smelter receives concentrates from
company-owned mines; composition of these concentrates often is
similar with respect to copper content and amounts and types of
impurities. A custom smelter buys the concentrate from other
producers, processes it, and sells the product. Toll smelters
charge a toll for processing the concentrate and return the
product to the mine owners for them to sell (3-2). The
composition of concentrates processed in custom and toll smelters
usually varies in copper content and impurities. Different types
of concentrates are usually stored in separate bins at the
smelter and are combined to form a specific blend before being
fed to the process.
Copper concentrates are recovered from various types of
ores. Of an estimated 93 million tons (84.4 Tg) of copper mined
domestically in 1977, about 99 percent was produced from copper
ores (ores in which copper is the main recoverable metal) and 1
percent from complex base metal ores (3-1). In addition to
domestic ores, some 516,731 tons (469 Gg) of copper in the form
of ores and concentrates was imported and processed at U.S.
smelters (3-3).
Copper deposits normally contain copper sulfide minerals;
the three most abundant are chalcopyrite (CuFeS2), chalocite
(Cu2S), and bornite (Cu5FeS4). Weathering may create deposits of
oxidized copper minerals; of these, the most abundant are azurite
3-2
-------
(2CuCC>3 . (OH^) and malachite (CuC03 . Cu (0H)2). The copper
content of ores that are economically extracted from the mine
ranges between 0.41 and 4.5 percent. On the average the copper
values of most ores extracted are less than 1 percent.
In addition to copper, the most common constituents of the
ores are sulfur, iron, and arsenic. Some ores contain
appreciable quantities of gold, silver, molybdenum, nickel,
platinum, selenium, tellurium, palladium, rhenium, lead, and
zinc.
Several other raw materials are used in production of
primary copper in addition to the copper concentrates. These
include agents that are added to promote or enhance the various
process reactions, such as fluxing agents, oxygen, and reformed
natural gas. In addition to such agents, other materials can be
added to the process for recovery of their copper values. These
include, for example, particulates and/or sludges collected in
air and water pollution control devices, cleanup materials, and
occasionally scrap copper. Most of these residues are recycled
within a plant, although they are sometimes transferred from one
plant to another.
Production and Capacity—Anode and fire-refined copper are
the principal products of copper smelting. Anode copper is
shipped to the electrolytic refinery for removal of the remaining
impurities, whereas fire-refined copper is sold directly after
smelting for nonelectrical applications.
3-3
-------
The major end uses of copper include electrical equipment
and supplies, building construction, consumer and general
products, industrial machinery and equipment, transportation
equipment, and accessories. About one-third of all annual copper
consumption is for electrical equipment and supplies (3-4).
Important byproducts of primary copper include arsenic, selenium,
platinum, palladium, gold, silver, molybdenum, tellurium, zinc,
and lead. Minor byproducts include iron, sulfuric acid, copper
sulfate, and various other chemicals. Sulfuric acid is produced
at copper smelters in sulfur dioxide control systems. Although
most of this acid is sold at a loss because of the distance
between the smelter and the market, smelters located near markets
for sulfuric acid do make a profit.
Primary copper production in 1977 was 1.6 million tons (1.45
Tg), with a value of $214 million (3-3). These figures indicate
that the industry utilized 69 percent of the total plant
capacity. The Bureau of Mines estimates that domestic primary
copper production will be 2.02 million tons (1.8 Tg) in 1985 and
2.57 million tons (2.3 Tg) in 2000. Based on these estimates,
the annual growth rate for primary copper production would be
3.85 percent from 1977 to 1985 and 1.64 percent from 1985 to
2000. By use of these factors production during the years 1980,
1985, and 1990 can be estimated, as shown in Table 3-1.
During the period from 1974 to 1977 the price of copper
fluctuated between $0.7706 per lb ($1.69 per Kg) and $0.6453 per
lb ($1.42 per Kg). In 1977 the price of domestic delivered
3-4
-------
TABLE 3-1
U.S. PRIMARY COPPER INDUSTRY STATISTICS**
(tons except as noted)
Production
Mine (recoverable copper) 1,490,000
1980 1,669,000
1985c 2,015,000
1990 2,186,000
1995 2,372,000
2000 2,573,000
Smelter 1,394,432
Refinery 1,600,000
Imports
Total copper content
(unmanufactured) 516,731
Exports
Unmanufactured 113,544
Refined copper (bars, ingots, etc) 51,528
Consumption
Refined copper 2,182,033
Average U.S. producer price ($/lb) 0.6698
Total value of annual refinery production (millions $) 214
* 1977 statistics unless otherwise noted.
Sources: Mineral Industry Survey. Copper industry in
1977. U.S. Department of Interior, Bureau of Mines, Washington
D.C. December 1977.
Mineral Industry Survey. Copper industry in August 1978.
U.S. Department of the Interior, Bureau of Mines, Washington, D.C.
October 27, 1978.
® Schroeder, H.J. Mineral Commodity Profile - 3. Copper.
U.S. Department of the Interior, Bureau of Mines, Washington, D.C.
June 1977.
Note: Metric conversion table is given in front matter.
3-5
-------
copper was $0.6696 per lb ($1.47 per kg), down 3.8 percent from
1976 (3-3). The 1977 domestic prices of lead, zinc, molybdenite
concentrate, gold, and silver, as reported by the Bureau of
Mines, were $0.3070 per lb ($0,675 per kg), $0.3260 per lb
($0,717 per kg), $3.68 per lb ($8.10 per kg), $148.31 per troy oz
($4.77 per g), $4.62 per troy oz ($0,149 per g), respectively.
Prices of gold, silver, and molybdenite concentrate have risen
sharply in the last year.
Cost of producing copper by conventional and
hydrometallurgical methods increased 85 percent from 1972 to
1976. This increase was mostly due to increased costs of labor
and energy (3-5). The Bureau of Mines estimates the production
costs for a 100,000 ton (907 Gg) per year smelter built in 1977
at $0,128 per lb of copper ($0,282 per kg) (3-6,3-2).
Companies—The primary copper industry comprises 11
companies that operate 16 primary smelters and 11 primary
refineries. Table 3-2 lists the companies and production
information. All of the smelter production is located in
Arizona, Michigan, Montana, Nevada, New Mexico, Tennessee, Texas,
and Utah. The domestic primary copper industry employs over
60,000 people in mining through refining. Many of the companies
producing primary copper are vertically integrated and therefore
are involved in two or more process segments. Often these firms
are involved in processing other valuable metals, such as lead,
zinc, gold, and silver. In some cases recovery of these metals
makes the mining and processing of copper ores economical.
3-6
-------
TABLE 3-2
U.S. PRIMARY COPPER PRODUCERS*t
Company and location
Description
Capacity
(tons/year)
Acid plants
Products
U)
I
•~J
AMAX, Inc
Carteret, N.Y.
The Anaconda Company
Anaconda, Mont.
Great Falls, Mont.
ASARCO Incorporated
Amarillo, Tex
El Paso, Tex.
Hayden, Ariz.
Tacoma, Wash.
Refinery
Smelter
Refinery5
RefineryS
Smelter
Smelter
Smel ter/ref meryU
276,000
210,000
252,000
420,000
122,500
N. A.
Yes
N.A.
N. A.
Yes
175,000 Yes
131,500/156,000 Yes/N.A.
Electrolytic copper
Anode copper, sulfuric acid
Electrolytic copper
Electrolytic copper
Anode copper, refined lead
zinc oxide, sulfuric acid,
dore, and cadmium oxide
Anode copper, sulfuric acid
Electrolytic copper, lead dust
sulfuric acid, sodium selenicfe
dore', liquid SOj, arsenic,
arsenic tnoxide, nickle
sulfate
Cerro Corporation
St. Louis, Mo.
Cites Service Company
Copperhill, Tenn.
Copper Range Company
White Pine, Mich.
Refinery^
Smelter
44,000
22,000
N.A.
Yes
Smeltcr
80,500
None
Electrolytic copper
Copper billets, cement copper,
zinc concentrates, sulfuric
acid, iron oxide pillets,
liquid SC>2, ferric sulfate
copper sulfate, oleum,
organic chemicals, fungicide
Fire-refined copper
Inspiration Consolidated
Copper Company
Miami, Ariz
Smelter/refinery 17 3,500/70,000 Yes/N.A.
Electrolytic copper, sulfuric
acid, selenium, gold, silver
rhodium
Kenrucutt copper Corp.
Ga i t ] i' I o , Lit ,ih
Smelter/refinery 14 0,000/191,000 Yes/N.A.
Electrolytic copper, platinum
qroup metals, gold, silver,
selenium, sulfuric acid,
molybdenite concentrate
(continued)
-------
TABLE 3-2 (continued)
Company and location
Description
Capacity
(tons/year)
Acid plants
Products
Hurley, N Mex.
Smelter
96, 500
Yes
Fire-refined copper,
molyodenite concentrate,
sulfuric acid
Hayden, Ariz.
Smelter
87,500
Yes
Anode copper, molybdenite
concentrate, sulfuric acid
McGill, Nev.
Smelter
4 2,000
Yes
Blister copper, sulfuric acid
Baltimore, Md.
RefineryS
276,000
Yes
Electrolytic copper
Magma Copper Company
San Manuel, Ariz.
Smelter/refinery
266,000/200,000
Yes/N.A.
Electrolytic copper, sulfuric
acid, molybdenite concentrate
Phelps Dodge Corporation
Morenci, Ariz.
Smelter
175,000
Yes
Anode copper, sulfuric acid
Douglas, Ariz.
Smelter
157,500
None
Anode copper, sulfuric acid
Hildago, N. Mex.
Smelter
175,000
Yes
Anode copper, sulfuric acid
Ajo, Ariz.
Smelter
63,000
Yes
Anode copper, liquid SO2
El Paso, Tex.
Refinery®
420,000
N. A.
Electrolytic copper
Laurel Hill, N.Y.
Refinery§
72,000
Electrolytic copper
Southwire Company
Carrollton, Ga.
Refinery®
72,000
N. A.
Electrolytic copper
* Some of the data provided in these documents have been altered on the basis of information in PEDCo files.
* Sources:
Schroeder, H.J. Mineral Commodity Profile-3. Copper-1977. U.S. Department of the Interior, Bureau of
Mines, Washington D.C. June 1977.
American Bureau of Metal Statistics. Nonferrous Metal data 1977. New York, New York.
5 Some refineries produce other products including gold, silver molybdenum, nickle, selenium, tellurium,
arsenic, rhenium, lead, and zinc. The specific plants that produce these products are not considered in this
study.
11 Refinery temporarily suspended operations as of January I, 1979.
Note Metric conversion table is given in front matter.
-------
Energy Consumption—In 1973 the domestic primary copper
industry consumed approximately 221 trillion Btu of energy (342
TJ) (3-7). The average unit consumption rate, including all
processes in mining, concentrating, smelting, and refining
segments, was 101.4 million Btu per net ton (118 GJ per Mg) of
refined copper. Of the total, smelting consumed 27.24 million
Btu per net ton (31.7 GJ per Mg) of anode or fire-refined copper.
Among the major nonferrous metals, copper ranks second to
aluminum in energy consumption. Much energy is wasted because
conventional production of copper is not continuous. Several new
energy-saving processes are beginning to gain acceptance in the
industry (3-8). These include flash smelting (Outokumpu Oy),
continuous smelting (Noranda), electric furnace smelting, and
various hydrometallurgical techniques. Currently one modified
Noranda process, one Ourokumpu Oy process, three electric furnace
smelters, and several hydrometallurgical processes are in use.
Although other producers may opt for these processes because of
environmental and energy considerations, continued acceptance
will depend also on markets.
There is, in fact, some dispute over the energy-saving
qualities of these alternative processes. A recent article
indicates that electric furnace smelting and some
hydrometallurgical techniques consume more energy than
conventional reverberatory smelting and that the production costs
are considerably higher (3-9).
3-9
-------
Outlook—A number of variable factors may lead to major
alterations in the domestic copper industry as copper producers
attempt to keep the industry economically viable. These factors
include environmental regulations, increasing production costs
with decreasing productivity, competition from foreign producers,
excess copper stocks, and increased substitution of other
materials, all leading to a depressed copper market.
The principal environmental problem is control of the sulfur
dioxide emitted from conventional reverberatory furnaces.
Control is difficult with present technology because the
concentration of sulfur dioxide in the flue gas is low. Under
current environmental regulations, copper producers will be
forced to retrofit their plants with acceptable air pollution
control devices or to introduce alternative processes (flash
smelting, continuous smelting, electric furnace smelting, or
hydrometallurgical processes), which are reported to be more
energy-efficient and environmentally sound (3-4).
Copper production costs have climbed while productivity has
remained constant or declined slightly (3-4). Most of the 85
percent increase in production costs during the period from 1972
to 1976 is attributed to increased costs of energy and labor;
however, other factors are also involved. Much of the copper
industry's total capital expenditures during the last decade
(36.5 percent in 1975) have been on pollution control (3-10).
Although these expenditures may benefit the environment, they do
nothing to increase productivity. It is estimated that past and
3-10
-------
future expenditures for pollution control will increase
production costs by a total of 15 percent (3-10). Another reason
for increasing production costs is the decline in grades of ore
being extracted in the United States. As the percentage of
copper in the ore decreases, the extraction costs increase
rapidly.
Imports have been gaining the competitive edge over the
domestic industry, reaching an all-time high in 1977 and 1978.
Most foreign copper producers are extracting ores that have
higher copper values than the U.S. deposits, leading to higher
copper production at a lower cost. Also, nationalized industries
in Chile, Zambia, and Zaire find it advantageous to produce
copper at the maximum possible rate (3-9). This practice
increases the inventory of finished copper and drives copper
prices downwards. Recently, internal strife has caused severe
production problems in many of these countries, contributing to a
short-term decrease in copper inventories.
Imports accounted for 25 percent of total refined copper
consumption in 1977. In the first half of 1978 a substantial
price differential between U.S. prices and import prices caused a
large increase in imports. Since then, changes in the pricing
structure have brought domestic prices into line with import
prices. In the second half of 1978 exports exceeded imports for
the first time (3-11). Weakness of the dollar on foreign markets
is partially responsible for this turnaround. Recently,
3-11
-------
President Carter rejected a recommendation of the International
Trade Commission to limit the amount of imported copper entering
the United States.
A recent study conducted by Charles River Associates
generated forecasts of prices for copper, lead, and zinc through
1985 (3-12). Two scenarios (one for moderate growth and one for
rapid growth) were developed based on various assumptions
regarding disposal of the excess copper stock and international
economic growth. Both the moderate-growth and the rapid-growth
scenarios predict steady increases in the real (deflated) U.S.
prices for copper. In constant 1978 dollars, the moderate-growth
scenario shows copper prices increasing from $0.70 per lb ($1.54
per kg) in 1977 to $0.83 per lb ($1.89 per kg) in 1985. In the
rapid-growth scenario, prices rise from $0.70 per lb ($1.54 per
kg) in 1977 to $1.17 per lb ($2.57 per kg) in 1985. In current
dollars the 1985 price of copper is projected to be $1.20 per lb
with moderate growth and $1.68 per lb ($3.70 per kg) with rapid
growth.
During recent years the inventory of stocks has been
building. Industry analysts estimate copper stocks at about 1.4
million.tons (1.3 Tg) at the end of 1977 (3-12). Approximately
75 percent of these stocks were held by warehouses and copper
producers. With this excessively large inventory, the impact on
the price of copper could be severe. In the last quarter of 1978
and the first quarter of 1979, stocks of copper decreased
sharply, while the price of copper increased (3-11). This change
3-12
-------
can be attributed to several factors such as internal strife in
several countries and weakness of the dollar in foreign currency
markets. Also economic analysts indicate the possibility of a
recession in the near future, and the increase in copper prices
may be the inflationary rise that precedes a recessionary period.
In any event, the situations described above have contributed
temporarily to improved economic conditions for U.S. copper
producers.
Increasing substitution of aluminum and plastics for copper
acts as a restraint against price increases. As copper prices
rise, substitution becomes more attractive to the manufacturer.
Therefore, the domestic copper producers must keep their prices
in line with both substitutes and imports.
The combination of these factors has caused the domestic
copper market to slide into a depressed state. Some producers
are operating at a loss (3-9). Eventually marginal producers may
be forced to close their facilities because of their inability to
compete.
Increasing the domestic producer's share of the copper
market will require a great deal of research on new technologies.
Although alternative processes, such as flash and continuous
smelting, have been developed for smelting and refining, these
two segments only represent one-third of the total production
costs (3-9). The greatest needs are for cost-effective,
environmentally sound, and energy-saving technologies for mining
3-13
-------
and concentrating, which represent two-thirds of production
costs.
The Bureau of Mines and industry are conducting research on
new techniques in geochemical explorations, methods for
eliminating SC>2 trace elements from smelters, and new leaching
agents (3-1). Industry trends may include greater application of
geophysical instrumentation, more use of large mining equipment,
more use of conveyor belts and draglines, and greater application
of ion exchange electrowinning technology.
Future smelter capacity is expected to fall short of both
mine production and demand by 1985. Only minor expansion of
existing facilities is planned. Any major expansion will not
come on line before 1985, partially because of the 5- to 6-year
lead time for planning and construction. Recently the adverse
market conditions have caused temporary closing of several
refineries and one smelter. This will further aggravate the
future capacity shortage.
The projected domestic demand for copper in 2000 is 3.5
million tons (3.2 Tg) (3-1). Such a demand would place severe
strains on domestic production, which estimates indicate will
fall 927,000 tons (841 Gg) short of domestic demand. This will
cause a huge influx of imports and will adversely affect the U.S.
balance of payments.
Process Description
Copper metal is recovered from copper ore concentrates by
pyrometallurgical processing, usually followed by electrolytic
3-14
-------
refining to remove the remaining impurities. Fourteen of the
sixteen domestic copper smelters produce anodes for further
refining at twelve refineries. The other two smelters produce
fire-refined copper for nonelectrical applications. Figure 3-1
is a representative flow sheet of operations at copper smelters
and refineries.
Pyrometallurgical Processing—Pyrometallurgical processing
converts copper ore concentrate into an impure copper metal
called either anode copper or fire-refined copper, depending on
the future use. Pyrometallurgical processing consists of
roasting or drying, smelting, converting, and fire refining.
One of the first operations at a copper smelter is roasting
or drying to prepare the concentrate for smelting (Process No.
1). Roasting is done primarily to control the amount of sulfur
in the ore so that subsequent processes can operate effectively.
In addition, roasting dries and preheats the concentrate,
volatilizes some of the impurities, and oxidizes some of the
iron. Most of the reactions in roasting involve the pyrite
(FeS2) in the concentrate, because iron reacts preferentially
with oxygen whereas copper has a high affinity for sulfur.
Typical reactions are (3-13):
FeS
2
-» FeS + S
(1)
S + °2 "" S02
(2)
2FeS + 302 -» 2FeO + 2SC>2
(3)
2S02 + 02 3S03
(4)
3-15
-------
u>
I
flOWdi
lip
^ LIQUID HASTE
9 ATMOSPHERIC EMISSION
9 SOLID HASTE
»rriwn
|«E ¦rf[N!TCB Sl«G
flHUS
PfttC|P|I*TfS
flirt OUSTS
PASTC CMRM
QlVttN
Figure 3-1. Flow chart depicts primary copper smelting and refining (numbers
correspond to process numbers in text).
-------
Reactions 2 and 3 are strongly exothermic; with sufficient sulfur
in the concentrate, the reactions become autogenous and no
additional fuel is needed.
Roasting produces no direct solid waste. All solids from
the roaster and particulates collected from the off-gases are
sent to the next process. At least one smelter recovers metals
such as arsenic from the flue dusts before recycling. High
concentrations of impurities may force disposal of some
particulates. Off-gases from the roasters contain sulfur
dioxide, but the concentration may be too low for conventional
sulfur recovery. Presently eight of sixteen copper smelters are
roasting the concentrates. Of those, four treat the roaster
gases in an acid plant. Operation of the acid plant yields a
weak acid stream called "acid plant blowdown," treatment of which
could generate a solid waste, depending on the method of
disposal.
The copper industry uses two types of roasters, the
multiple-hearth and the fluidized-bed roasters. A
multiple-hearth roaster is a vertical cylinder with 8 to 12
hearths. A central shaft rotates rabble arms that move the ore
across the hearths. Concentrates fed into the top of the roaster
fall from hearth to hearth. Roasted concentrate is removed from
the bottom hearth and sent to the next process. In a
fluidized-bed roaster the upward motion of a gas stream supports
a dense mass of finely divided concentrate in which the roasting
reactions occur. Because the concentrate particles and gas are
3-17
-------
in close contact in the bed, little excess air is needed and all
of the oxygen is consumed; sulfur dioxide concentrations in the
gas stream are therefore high.
The off-gas from a multiple-hearth roaster usually is not
treated in an acid plant but is released to the atmosphere after
particulate recovery. Flue gas from the fluidized-bed roaster,
with higher sulfur dioxide content, is treated in a contact acid
plant for sulfur fixation. Concentrate is continuously fed into
the roaster, and roasted concentrate is removed by an overflow
near the top of the bed. Roasted concentrate, or calcine, is
sent to the next process.
Concentrates often are not roasted because some
concentrators can control the amount of sulfur in the ore or
because the advantage of removing sulfur and volatile impurities
is not greater than the disadvantage of handling a dusty calcine
(3-14). Drying is done in special dryers, such as rotary kilns,
by air drying, or by generating the multiple-hearth roasters at a
lower temperature. Any particulates from drying are collected,
combined with the solids from the dryer, and sent to the next
process; thus drying generates no solid wastes. Dryer off-gases
do not require sulfur control because the lower operating
temperatures do not cause conversion of sulfur to sulfur dioxide.
Four smelters do not roast or dry the concentrate but operate as
"green feed" smelters.
Roasted, dried, or "green" concentrates are smelted to
remove most of the iron and some other impurities and to separate
3-18
-------
the feed into a slag and a copper-iron-sulfide matte that can be
efficiently processed in subsequent operations (Process No. 2).
Smelting, like roasting, takes advantage of the high affinity of
copper for sulfur. Concentrates, flux, and miscellaneous plant
scrap (cleanup material) are charged to the furnace and melted.
During smelting a complex series of reactions take place and the
charge separates into three fractions (3-15). Some sulfur in the
charge forms sulfur dioxide, which leaves with the combustion
gases along with the volatile components of the charge. Iron
oxides and silica in the charge combine to form an iron-silica
slag, and iron sulfides and copper sulfides form a molten matte.
The copper-iron-sulfide matte and slag are both tapped from the
furnace; the matte is sent for further processing, and the slag
is discarded in the slag dump.
Slag is the major solid waste from copper smelting. It is
usually tapped from the furnace, transported molten to the slag
pile, hot dumped, and allowed to solidify. At some copper
smelters the slag is granulated as it is tapped from the furnace.
Particulates are collected from the off-gases and are usually
recycled to the process, although those with accumulations of
impurities may need to be discarded. The furnace off-gas also
contains sulfur dioxide. The feasibility of controlling the
sulfur emissions depends on the type of furnace, which affects
the concentrations of sulfur dioxide in the off-gas.
The four furnaces used in the domestic industry are
reverberatory, electric, flash, and Noranda. Reverberatory
3-19
-------
smelting furnaces are the oldest and most widely used type. The
other three are used at only a few plants.
A reverberatory furnace is a long, rectangular structure,
usually 110 ft (34 m) long and 34 ft (10 m) wide, with a
suspended roof. Capacities range from 1600 to over 2000 tons
(1.45 to over 1.8 Gg) of charge. Calcine from the roaster and
collected flue dusts are fed into hoppers staggered along both
sides of the furnace and are added to the furnace through drop
holes in the roof (3-16). Burners at one end of the furnace are
designed so that the flame from the burner strikes the roof and
reverberates downward, melting the charge. As the charge melts,
a slag and a matte layer are formed and are tapped from the
furnace periodically. The matte is transferred to the converter
aisle, and the slag is discarded. Smelting produces large
amounts of slag as much as 6,000 lb per ton (3,000 kg per Mg) of
copper produced (3-17). The reverberatory furnace uses outside
combustion air, which dilutes the sulfur dioxide concentration
below the levels needed to produce sulfuric acid. The flue gas
is released to the atmosphere after particulate removal.
Electric smelters utilize the resistance produced by
electric currents to provide the heat for smelting. An electric
furnace is rectangular with a sprung-arch roof. Power is
supplied to the furnace through Soderberg electrodes extending
down from the furnace centerline and immersed in the slag (3-16).
Around each electrode is a ring of superheated slag generated by
the electrical resistance of the slag. Calcine and fluxing
3-20
-------
materials are added to the furnace as close to the electrodes as
possible. As it melts, the calcine separates into matte and
slag, which are periodically tapped from the furnace. The
electric furnace produces the same volume of sulfur dioxide as
the reverberatory furnace, but because the gas is not diluted by
combustion gases sulfur dioxide concentration can be maintained
at a level high enough for conventional sulfur recovery in an
acid plant. Operation of the sulfuric acid plant generates a
weak acid stream containing suspended and dissolved solids, which
are disposed of or recycled.
Flash smelting produces matte and slag by a continuous
technique. Concentrates and fluxes processed by flash smelting
must be fine-grained and almost "bone-dry." The dried
concentrates and fluxes are injected into a combustion chamber
along with preheated air (3-15). Part of the sulfur in the
concentrate burns in the chamber, maintaining smelting
temperature. Matte and slag formed in the combustion chamber
fall to the bottom of the furnace and separate into layers.
Matte is tapped and transferred to the converters. The slag
contains too much copper to be discarded and is charged to an
electric furnace (Process No. 3) with fluxing agents to reclaim
the copper values. As the charge separates into layers, the
matte is transferred to the converters and the slag is disposed
of. A flash furnace is more thermally efficient than either a
reverberatory or electric furnace and produces a stack gas
3-21
-------
containing sulfur dioxide in concentrations high enough for
sulfuric acid recovery.
The Noranda process is another continuous smelting
technique. The Noranda furnace is a horizontal cylinder, into
which a mixture of concentrate and flux is fed with fuel and
oxygen (3-15). Matte tapped from the furnace is sent to the
converter aisle. Because slag from the Noranda vessel contains a
relatively high percentage of copper (10 to 12 percent), it is
treated in a crushing and flotation facility to claim the copper
values. Tailings from the crushing and flotation facility are
disposed of (3-15). With oxygen enrichment of inlet air, the
stack gas from the Noranda furnace contains about 13 percent
sulfur dioxide and is used for sulfuric acid production, which
generates a solid waste. Matte from smelting is separated from
most of the remaining impurities and reduced to crude blister
copper in the copper converter (Process No. 4). Converting is a
two-step batch operation in which matte is charged to the
converter along with a silica flux. The first step called the
"slagging period," then follows. Air or oxygen-enriched air is
blown into the matte, preferentially oxidizing iron sulfide in
the matte and leaving molten cuprous sulfide (Cu2S). The
following reactions take place during slagging (3-13):
2FeS + 302 ¦* 2FeO + 2S02
FeO + SiC>2 -» FeO'SiC>2 (slag)
Iron and silica form a slag, and sulfur dioxide leaves the
converter in the gas stream. After essentially all of the iron
3-22
-------
has been removed from the matte, blowing is stopped and the slag
is removed from the converter and returned to the smelting
furnace. After the slag is removed, additional matte and flux
are added to the converter. Also, because the reactions taking
place during slagging are exothermic, copper scrap and solidified
matte are added to control the heat. Another "slagging period"
then begins. This process is continued until sufficient cuprous
sulfide has been accumulated in the converter (3-18).
The second converter step, called the "blister-forming
period," then begins. Air is blown in, oxidizing the cuprous
sulfide to cuprous oxide, which is in turn reduced to copper by
remaining cuprous sulfide. The following reactions occur during
blister-forming (3-13):
2Cu2S + 302 -> 2Cu20 + 2S02
2Cu20 + Cu2S -» 6Cu + SC>2
The blister-forming period continues until almost all of the
sulfur has been removed, after which the blister copper is
removed for further treatment.
Slags produced during slagging are relatively high in copper
values and are recycled "hot" to the smelting furnace. The flash
and Noranda installations treat converter slag with the smelting
furnace slag. Gas streams from the converter contain enough
sulfur dioxide for recovery by conventional methods. Usually the
converter gases are combined with those from the furnace or
roasters for particulate removal and sulfur recovery in the
3-23
-------
sulfuric acid plant. The collected particulates are recycled,
and wastes from sulfuric acid production are those described
earlier.
Two types of converters are used in the copper industry, the
Peirce-Smith converter and the Hoboken converter. The
Peirce-Smith converter is predominant in the domestic industry;
the Hoboken converter is used at only one location. Both types
of converters operate as described earlier, the major differences
between them being configuration and size. The Peirce-Smith
converter is a horizontal cylinder 13 ft (4m) in diameter and 30
ft (9 m) long, with a centrally located charging mouth. Matte,
fluxes, and scrap are charged through the mouth and the converter
is then rotated so that the mouth is located under a hood for gas
collection. The Hoboken converter is similar to the Peirce-Smith
converter except that it is fitted with a side flue that is a
part of the converter. The side flue is connected to a fixed
vertical flue by a cylinder that is free to rotate with the
converter. Matte and flux are charged through a small mouth on
the side.
Blister copper is fire-refined to remove impurities and to
adjust the sulfur and oxygen levels before casting (Process No.
5). Blister copper is charged to the fire-refining or anode
furnace along with some silica fluxes. Air is blown into the
blister copper, oxidizing the remaining sulfur, and other
impurities such as iron, zinc, and tin, and some of the copper.
The impurities combine with silica to form a slag, which is
3-24
-------
removed from the furnace. After slag removal the cuprous oxide
remaining in the copper is deoxidized by adding coke, by
inserting green hardwood poles below the surface of the bath
(called "poling"), or by injecting reformed natural gas into the
bath, the most widely practiced method. The copper is then
poured into molds for further treatment. Most copper is cast
into an anode shape suitable for further processing in an
electrolytic refinery. A small percentage is further
fire-refined and cast for direct sale. Slag from the
fire-refining furnace is not a solid waste because it is recycled
to the converter or the slag treatment facility for copper
recovery.
Sulfuric Acid Plant—At most copper smelters the waste gas
streams are treated in a sulfuric acid plant to recover sulfur
before releasing the gases to the atmosphere (Process No. 6).
Sulfur dioxide in the gas stream is recovered by the contact
process. The process consists of several operations, the most
important of which are conversion of sulfur dioxide to sulfur
trioxide by use of a catalyst and absorption of the sulfur
trioxide by sulfuric acid. Gas streams to be processed in the
acid plant must be clean and dry to protect the catalyst and
prevent excessive corrosion. The gas is cleaned first in cyclone
collectors or an ESP and then in a scrubber, where it is also
partially cooled by contact with scrubbing acid. Cleaned gas is
further cooled to approximately atmospheric conditions either in
an indirect cooler or by direct contact with water or weak
3-25
-------
sulfuric acid. Cleaned, cooled gas is virtually free of
impurities except for water vapor and sulfuric acid mist. The
acid mist, a carrier of arsenic, is usually removed by passing
the gas through a bed of coke or an ESP. Finally the gas is
dried in a packed tower irrigated with drying acid. The clean,
dry gas is then passed through a catalyst bed, either vanadium
pentoxide or platinum, in which the sulfur dioxide and oxygen
react to form sulfur trioxide. The reacted gases are finally
passed through absorbing towers, where the sulfur trioxide is
absorbed by strong sulfuric acid. Acid plants are designed with
one catalyst bed and absorber (single-contact) or two catalyst
beds and absorbers (double-contact).
Scrubbing of the gas stream to remove particulate matter
generates a weak acid waste stream containing suspended and
dissolved solids. This "acid plant blowdown" is use$3 as a flue
gas conditioner or disposed of in lagoons or tailings ponds.
Electrolytic Refining—Anode copper is further refined in an
electrolytic process to produce the high-purity copper that is
specified in today's markets. The process uses cathode starting
sheets, sulfuric acid, and an electric current. Electrolytic
refining consists of the following steps: electrolysis,
electrolyte purification, melting and casting, and slime
treatment.
Copper anodes from the smelter are refined electrolytically
to remove impurities that can adversely affect the electrical
conductivity of copper (Process No. 7). Present quality
3-26
-------
specifications require that the impurities in the anode copper,
which are less than 1 percent, be reduced to approximately 0.05
percent. This is accomplished by immersing cathode "starting
sheets" in a lead-lined concrete cell containing sulfuric acid,
copper sulfate, and various additives such as glue and Goulac.
The copper anodes and cathodes are spaced alternately and are
electrically connected in parallel. Each cell is connected to
adjacent cells by a bus bar. As current is applied, the anode is
dissolved electrolytically and the copper is deposited on the
cathode. Impurities in the anode either dissolve in the
electrolyte or fall to the bottom of the cells as slime (3-13).
After the-anodes have dissolved to about 15 percent of their
original weight (about 28 days) they are pulled from the cells,
washed free of slime and electrolyte, and returned to the anode
furnace for recasting. An anode cycle of 28 days will produce
two to three cathode pulls. Pulled cathodes are washed and
transferred to the melting furnace.
Other than a few miscellaneous slurries and sludges,
electrolysis produces essentially no solid wastes. Slimes that
collect on the bottoms of the cells contain gold, silver,
sellenium, tellurium, and platinum group metals and are processed
for recovery of these metal values. The electrolyte becomes
laden with soluble impurities and copper, which must be removed
to maintain the efficiency of the solution and to prevent
coprecipitation of the impurities at the cathode (Process No. 8).
As much as 75 percent of the electrolyte is transferred to the
3-27
-------
purification section each month (3-13). Purification is done in
liberator cells by electrolysis. Insoluble lead anodes and
copper starting sheets are inserted into the liberator cells, and
an electric current is applied. Copper in the solution is
deposited on the starting sheet, forming a poor-quality cathode
that is returned to the smelter to be melted and cast into
anodes. The cathode contains impurities such as antimony,
bismuth, and lead. Sludge that forms on the floor of the
liberator cells is returned to a smelter or sold to contractors.
In a few purification operations dialysis equipment is used
to recover some sulfuric acid from the "black acid" liquor for
recycle to the electrolysis cells; this procedure reduces acid
make-up costs. Dializers are likely to be used at refineries
where the capital and operating costs of the equipment compare
favorably with the cost (and availability) of commercial acid,
such as that from a nearby smelter's acid plant. The
decopperized solution is dewatered in vacuum evaporators, leaving
a sludge of nickel, iron, and zinc from which a crude nickel
sulfate is extracted. The "black acid" liquor from the
evaporators is sometimes used in leaching operations or may be
sold to fertilizer manufacturers (3-15,3-19).
Electrolytically purified copper cathodes are melted in a
furnace in preparation for casting (Process No. 9). In addition
the oxygen content is adjusted to a final level of 0.01 to 0.03
percent in the furnace. Melting is done in reverberatory or arc
furnaces at large-volume refineries. Induction furnaces are used
3-28
-------
as holding furnaces behind the reverb or arc furnace; at smaller
refineries they are used for melting. No solid wastes result
from melting copper cathodes. Slags and dusts, if any, are
returned to the smelter.
Molten copper is cast into commercial shapes to meet
consumer needs (Process No. 10). Copper is poured into molds and
cast into wirebars, billets, cakes, ingots, ingot bars, or slabs.
Continuous casting technology is becoming widespread in the
industry because it offers advantages in energy usage quality
control. Casting produces no solid wastes.
Slimes that collect in the electrolytic cells contain
valuable metals, which are recovered in the slime treatment
process (Process No. 11). Slimes are removed from the cell and
decopperized either by acid leaching or by roasting followed by
an acid leach of the calcine. The decopperized slimes are
charged to the Dore furnace (a reverberatory-type furnace) along
with soda and silica flux for melting. Melting causes formation
of siliceous slag, which is tapped and removed from the furnace.
The charge is then blown, and a lime flux is added; this causes
formation of slag with high lead content. The siliceous slag and
the lead slag are returned to the anode casting furnace or are
sold to a lead smelter. Next a fused soda ash is added and the
charge is blown again, causing a soda slag to form. This slag is
removed from the furnace, leached with water, and processed
further for recovery of sellenium and tellurium. The Dore metal
is removed from the furnace and further treated for the recovery
3-29
-------
of gold, silver, and platinum-group metals. Slime treatment can
be done either on or off the site. The treatment produces no
solid wastes because all solids are recycled for recovery of
valuable metals.
Solid Waste Characterization
Sources and Quantities of Solid Waste
This section describes the sources and quantities of solid
wastes from primary copper smelters and electrolytic refineries.
The sources are readily identified and are similar throughout the
industry. There are, of course, some variations in waste
generation attributable to such factors as concentrate analysis,
smelting method, types of products, and degree of integration.
The potential sources of solid waste at copper smelters
include furnace slag, wet sludges, and in a few cases collected
particulates. Solid wastes at electrolytic copper refineries
consists of only a few miscellaneous sludges and slurries; these
occur in relatively small quantities because of the high purity
of the material fed to the refinery process (anode copper is at
least 99+ percent copper).
The largest quantity of solid waste generated at copper
smelters is furnace slag, which is typically "hot dumped" on the
land. A few smelters sell the slag for roadfill or landscaping,
and some use the slag onsite for mine backfill or road
construction. Research efforts are under way to find uses for
slag and to develop economical methods of recovering its metal
values. At present, though, because economic and market
3-30
-------
conditions usually preclude selling or reprocessing the slag,
most of this material is disposed of onsite near the smelter.
Slurries containing suspended and dissolved solids arise
from a number of sources including acid plant blowdown, DMA
purge*, wet scrubbers, blister cake cooling water, anode cooling
water, other contact cooling water, and plant washdown water. At
some plants the slurries are discharged to a small lagoon for
settling, then the solids are dredged and recycled for metal
recovery. At these plants this material does not constitute a
solid waste. At other plants the slurries are either discharged
directly to a tailings pond (when ore concentrating operations
are nearby) or to a lagoon, where solids settle and remain, or
are periodically dredged and disposed of onsite. At these plants
the slurries constitute a solid waste.
At all primary copper smelters the collected particulates
contain high concentrations of recoverable metals. The preferred
practice is to immediately recycle this residual to the process.
At a few plants the particulates are sold to lead smelters after
several cycles through the copper smelter, and at one western
smelter the dusts from the roaster and reverberatory flues are
processes onsite in an arsenic plant to produce arsenic trioxide.
* Three domestic smelters use a dimethylaniline (DMA)
absorption plant for sulfur fixation to produce liquid SO2• The
make-up and treatment of the DMA purge is similar to acid plant
blowdown (3—19). In this report all of the quantitative and
qualitative discussions of acid plant blowdown include DMA purge.
3-31
-------
By no means do these materials constitute a solid waste. At a
few plants the collected particulates are temporarily stored on
site before recycling, but this involves a small amount of
material and the storage time is generally short. Some plants
may dispose of collected particulates from secondary air
pollution control devices onsite, but PEDCo did not identify
specific locations where this is practiced; if it does occur, the
quantity of material involved is small.
In this investigation the quantification of solid wastes is
done by means of model plants, since a plant-specific inventory
is beyond the scope of this project. Models for the copper
smelting industry are based on the type of furnace used to melt
the charge: reverberatory smelter, electric smelter, Noranda
smelter, and flash furnace smelter (see Process Description). A
single model was developed for the electrolytic refining segment
of the industry. A model plant approach has certain
shortcomings, including the potential for either under- or
overestimating the quantities of solid waste actually being
generated. This problem is minimized in the present
investigation as a result of the following factors:
1. Several models were developed for the primary copper
industry, and therefore a greater percentage of the
industry is represented.
2. Average values are used for estimating any solid waste
generation factors; therefore any over- and
under-estimations of total solid waste production at
specific plants should negate one another.
3-32
-------
3. All available plant-specific data from site visits or
published reports were used to correct or adjust solid
waste production values.
Model 1: Reverberatory Smelting—Eleven smelters,
representing 66 percent of domestic smelting capacity, use
reverberatory furnaces to produce matte from the concentrate
(Figure 3-2). As of this writing, one of these smelters has
closed indefinitely and the future of two others is uncertain.
An average plant production of 140,000 tons (127 Gg) per year of
anode copper was selected to represent the model reverberatory
smelter. Production data for the model were derived by scaling
typical smelter production data to the production rate of 140,000
tons (127 Gg) per year or 400 tons (363 Mg) per day (based on 350
operating days per year). (Note: Quantities of input and output
materials are not included for many of the process operations,
because the emphasis here is on solid waste generation rather
than general materials balance). Actual plant production of
facilities represented by Model 1 ranges from 42,000 tons (38 Gg)
per year to 280,000 tons (254 Gg) per year. Reverberatory
furnaces may be charged with "green" concentrate (23 percent of
industry capacity), with concentrate from a rotary dryer or
multihearth roaster (36 percent of industry capacity), or with
concentrate from a fluid bed roaster (7 percent of industry
capacity). The broken lines in the model diagram represent these
three alternative charging methods. The flow of materials after
the concentrate preparation area is almost identical at all
reverberatory smelters.
3-33
-------
ro *rw>s*HtR[
< \
, fLUl |
CfWOUlONINC |
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—{ l»ttXJlS
(
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- *lfO®WO G*
- «oid rmssw;
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- Ciqcuir lis
TO DISPOSAL SITE
NOTE NUMERICAL VAIUIS EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 3-2. In the primary copper industry Model 1 rcprp.ients plants
with reverberatory smelting.
-------
The reverberatory smelter produces solid wastes as slag,
acid plant blowdown, and miscellaneous slurries. The slag is
periodically tapped and transferred to a slag disposal area.
Acid plant blowdown contains solids that are recycled to the
process, discharged to a lagoon for settling, or discharged to a
tailings pond. Some of the solids in the acid plant sludge are
potentially hazardous (3-26). Overflow from the lagoons is
discharged to a tailings pond, recycled to a mill concentrator,
or discharged, where the plant has an NPDES permit. Solids in a
lagoon at one smelter are dredged and sold. Miscellaneous plant
slurries such as anode cooling water and plant washdown water are
handled in a similar manner. Slurry discharges to the tailings
ponds are minor in relation to tailings volume, and their impact
on a volume basis is insignificant.
Reverberatory slag from this model is disposed at a rate of
336,000 tons (305 Gg) per year or 2.4 tons per ton of anode
copper. Acid plant blowdown is estimated to be 400 tons (363 Mg)
per year or 0.003 ton per ton of anode copper. Miscellaneous
plant slurries including cooling water, and plant washdown are
estimated to contain 2,400 tons (2.2 Gg) per year of dissolved
and suspended solids or 0.017 ton per ton of anode copper (3-17).
Applying a capacity utilization factor of 70 percent and by
taking into account known variations to the model, the results
shown in Table 3-3 were obtained when extrapolating these model
plant data to the entire reverberatory smelting segment of the
industry. Reverberatory slag is by far the major solid waste.
3-35
-------
TABLE 3-3
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY COPPER PLANTS
REPRESENTED BY MODEL 1
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Slag
2.4
2,352,000
1,842,000
Acid plant
blowdown
0.0003
2,700
1,300
Miscellaneous
slurries
0.017*
16,900
16,900
Total
2,371,600
1,860.200
* Value adapted from: Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refinery industry. 1977.
Note: Metric conversion table is given in front matter.
-------
If all reverberatory smelters were operating at 70 percent of
capacity and dumping all furnace slag, some 2,352,000 tons (2.1
Tg) per year of slag would be dumped on the land. Two smelters,
however, sell a total of about 500,000 tons (454 Gg) per year to
outside contractors, and a third smelter reports that 10,000 tons
(9.1 Gg) per year of its slag production is used as mine
backfill; accounting for these smelters reduces the total volume
of slag dumped on the land to 1,842,000 tons (1.7 Tg) per year.
Two other smelters periodically reclaim the copper from their
slag piles by sending the slag through the mill concentrator,
leaving added tailings disposal, or by processing the slag in a
heavy-media plant, leaving the tailings on land. Since slag
usually contains from 0.5 to 1 percent copper, the volume of
waste is not greatly reduced, and no credit is given for slag
disposal from these two operations.
Two reverberatory smelters use fluid bed roasters and
associated gas conditioning systems and operate acid plants. The
acidic effluent from the gas conditioning system at both smelters
contains recoverable copper. These solids, which at one smelter
amount to 29,000 tons (26 Gg) per year, are recycled to the
roaster (3-20). The acid plant blowdown is slurried to tailings
ponds in volumes that are insignificant in relation to tailings
volume. The model plant generates 420 tons (381 Mg) of blowdown
annually from the roaster acid plant while producing 140,000 tons
(127 Gg) of copper each year, or 0.003 ton of blowdown for each
ton of copper produced. (Converter acid plants are discussed in
3-37
-------
the next paragraph.) Combined annual production of the smelters
in the industry using fluid bed roasters to roast all or part of
the concentrate is 104,000 tons (94 Gg) at 70 percent of
capacity. Production of copper at that rate yields a total
annual blowdown of 300 tons (272 Mg) to be disposed of in
tailings ponds.
Nine of the eleven smelters in the reverberatory model
category treat converter offgases in contact acid plants. Based
on a generation factor of 0.003 tons of blowdown per ton of anode
copper and a capacity utilization factor of 70 percent, these
nine smelters, with a combined production of 813,500 tons (738
Gg). per year, would produce 2,400 tons (2.2 Gg) per year of
acidic slurry. Of these nine, however, five smelters, with a
combined production of 325,000 tons (295 Gg) per year at 70
percent of capacity, discharge the blowdown to the mill
concentrator or directly to tailings ponds. Three of the nine
smelters spray the blowdown into flues to precondition hot
process gas. The remaining smelter discharges the blowdown into
a series of lined lagoons, combining it with a slurry of spent
electrolyte from the refinery, then periodically dredges the
solids and sells them overseas. Available information indicates
that none of the plants in the reverberatory smelting category
disposes of acid plant blowdown by itself. The only plants
disposing of acid plant blowdown are those that discharge it to
tailings ponds, either directly or indirectly through the mill
concentrator. The quantity disposed is calculated to be 1,000
3-38
-------
tons (907 Mg) per year. On a volume basis, this quantity is
negligible in comparison to the volume of tailings discharged to
the pond. For example, at one integrated complex producing 750
tons (680 Mg) of anode copper per,day, approximately 60,000 tons
(54.4 Gg) per day of tailings is generated at the adjacent
concentrator. If this quantity were to be scaled by direct
proportion to the model smelter producing 400 tons (363 Mg) per
day, the mill concentrator would generate 32,000 tons (29 Gg) of
waste material per day. If acid plant blowdown is generated at
this rate of 400 tons (363 Mg) per year or 1.1 ton (1.0 Mg) per
day, the acid plant blowdown amounts to significantly less than 1
percent (0.003%) of the tailings volume.
Miscellaneous slurries are used in the mill concentrator as
makeup water or discharged to unlined ponds. Eight reverberatory
smelters with a combined annual capacity of 985,500 tons (894 Gg)
have concentrators onsite or nearby. It is assumed that all
miscellaneous slurries at these smelters are used in the
concentrator circuit, resulting in 12,000 tons (10.9 Gg) per year
of added solids disposal in tailings ponds while operating at 70
percent of capacity. It is further assumed that three
reverberatory smelters without concentrators discharge their
miscellaneous slurries to unlined ponds. These smelters have a
combined annual capacity of 411,000 tons (373 Gg) of copper.
Operating at 70 percent of capacity, they would contribute 4,900
tons (4.4 Gg) per year of solids to land disposal in lagoons.
3-39
-------
Model 2: Electric Smelting--Three domestic smelters,
representing 19 percent of industry capacity, use electric
furnaces to produce copper matte from ore concentrate. A model
plant producing anode copper at the rate of 140,000 tons (127 Gg)
per year [or 400 tons (363 Mg) per day based on 350 operating
days per year] represents this segment of the industry (Figure
3-3). Actual production of the plants ranges from 21,000 tons
(19.1 Gg) to 210,000 tons (191 Gg) per year.
Electric furnaces must be charged with dryed or roasted
concentrate. Two domestic smelters use fluid-bed roasters and
one uses a rotary dryer for this purpose. Materials flow after
concentrate preparation is similar at the three smelters.
Solid wastes from an electric smelter originate from furnace
slag, acid plant blowdown, and miscellaneous plant slurries.
Furnace slag is formed as the silica flux and iron oxides combine
in the molten charge. Slag is periodically tapped and
transferred to the slag disposal area. Offgas from fluid bed
roasters, electric furnaces, and converters is rich in S02 and is
treated in contact sulfuric acid plants to comply with air
emission regulations. Acid plant blowdown contains solids that
are recycled to the process or are disposed of in tailings ponds.
Miscellaneous plant slurries are handled in a similar manner.
The volume of slurries discharged to the tailing ponds is minor
in relation to tailings volume, and impact is minimal.
Particulates removed from smelter flue gases contain recoverable
metals and are recycled to the process.
3-40
-------
u>
I
NOTE
NUMERICAL VALUES EXPRESSEO IN THOUSANOS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
_ tailings
I *7 PONOS
I L-
ROASTER
CLARIF it h
SWAY
CHAMBER
10 ROASTER
PUG MILL
PROOUCTS
TO
PUG Mill
/^mSCELlAN(OuT\
cyclone
TO
PUG MILL
MILL CONCENTRATOR
CIRCUIT AND
TAILINGS WJIJO
CYCLONE
CYCLONE
FLUID BED
I ROASTER
WASTE
Ht AT
BOILER
WASTE
HEAT
BOILER
COPPER
ANODES
MO
REFINING FURNACE
AND ANOOE
CASTING WELL
ELECTRIC
FURNACE
CONVERTERS
CARBON
ELECTROOES
run
REVERTS
aui
OXYGfN
- REFORMED GAS
-MOID DRESSING
COOLING WATER
FLU*
OXYGEN
TO ATMOSPHERE
CONVERTER
SLAG
BAGHOUSE
CYCLONE
TO DISPOSAL SITE
TO ELECTRIC
ruRNACC
ROTARY
| ORYtR |
TO CONVERTERS
Figure 3-3. In the primary copper industry Model 2 represents plants
with electric smelting.
-------
Furnace slag from the model plant is disposed of at a rate
of 322,000 tons (290 Gg) per year, or 2.3 tons per ton of anode
copper (Table 3-4). Acid plant blowdown is estimated to be 0.003
ton per ton of anode copper, or 420 tons (381 Mg) per year.
Miscellaneous slurries including anode cooling water and plant
washdown water are estimated to contain 0.017 ton of solids per
ton of anode copper, or 2,400 tons (2.2 Gg) per year (3-17).
. Extrapolation of these model plant data to the electric
furnace segment of the smelting industry, considering known
variations, indicates that furnace slag is by far the largest
solid waste. If all electric smelters were operating at 70
percent of capacity and dumping all furnace slag, they would dump
639,500 tons (580 Gg) of slag on the land each year. One
smelter, however, consumes its entire slag production of 34,000
tons (30.8 Gg) per year in an iron pelletizing plant (3-22); thus
the total annual volume of slag dumped on the land is 605,500
tons (549 Gg) per year (Table 3-4). Only one of the smelters in
this category disposes of acid plant blowdown; the other two
smelters recycle the solids through the process. Producing at 70
percent of capacity this smelter would dispose 450 tons (408 Mg)
of blowdown in tailings ponds annually. Disposal of
miscellaneous slurries would contribute 4,700 tons (4.3 Gg) per
year at 70 percent capacity utilization (Table 3-4).
Model 3; Noranda Smelting—One domestic smelter uses a
modified Noranda smelting process (Figure 3-4) to produce a
high-grade matte of about 70 percent copper. The matte is
3-42
-------
TABLE 3-4
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY COPPER PLANTS
REPRESENTED BY MODEL 2
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Slag
2.3
639,500
605,500
Acid plant
blowdown
0. 003
850
450
Miscellaneous
slurries
0.017*
4,700
4,700
Total
645,050
610,650
* Value adapted from: Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refinery industry. 1977.
Note: Metric conversion table is given in front matter.
-------
10 CONCRETE
STORAGE PAO
FOR SEPARATE
treatment
SHOT
COOLER
C*CLONE
SCRUBBER
WASTE
HEAT
90IIER
DROPOUT
CHAMBER
CYCLONE
NOTARY
DRYfflS
NORANOA
VESSELS
CONVERTERS
' LU*
0**CEN
COLO DOPE
FLUE DUST
0**61"
SECONDAR ES
SIAC CRUSHING
CONCENTRATING
SICKENING
SlAG
CONCENTRATE
TAKINGS
<95
ACID
PLANT
WASTEWATER
TREATMENT PLANT
PARTICULATE
REFINING AND
ANODE CASTING
• riui
• OfYGtN
• REfORHtO GAS
• COOLING WATER
I COPPfR \
* I Atoors I
j V3/
c
TO CONVERTERS
/^celianeoJTn _
I SLURRIES
HILL
CONCENTRATOR
TO CONCENTRATE FEED
TO 0ISP0SAL SITE
NUWRICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 3-4, In the primary copper industry Model 3 represents plants
with modified Noranda smelting.
-------
further refined in the traditional converter and anode furnace
and cast into anodes for electrolytic purification at the nearby
refinery.
Solid wastes at the smelter are slag tailings, acid plant
blowdown, and solids in miscellaneous slurries. Although all of
the miscellaneous slurries are used in the mill concentrator as
make-up water, it is assumed that the solids eventually make
their way to the tailings ponds. Particulates removed from the
ESP, amounting to about 30 tons (27 Mg) per day, are stored on a
concrete pad and sprayed with water to prevent fugitive
emissions. A dust treatment plant, now in the preliminary design
stage, will be used to process these stockpiled residuals (3-23).
The slag, of relatively high copper content, is crushed and
treated in a flotation plant to recover some of the copper value.
The resultant slag tailings amount to 495,000 tons (449 Gg)
annually when copper is produced at full plant capacity of
228,000 tons (207 Gg) per year; thus the slag tailings generation
factor is 2.2 tons per ton of anode copper. Blowdown from the
acid plants is treated in a wastewater treatment facility, solids
i
are removed and placed in a pond. The solids are generated at a
rate of 0.003 ton per ton of copper, contributing 700 tons (635
Mg) per year to the sludge pond at 100 percent capacity. With a
generation factor of 0.017 ton per ton of copper (3-17), the
miscellaneous slurries add about 3,900 tons (3.5 Gg) of solids to
the tailings pond annually. After application of a capacity
3-45
-------
utilization factor of 70 percent, the total quantity of solid
waste produced annually at copper plants represented by Model 3
is 354,200 tons (321.3 Gg) (Table 3-5).
Model 4; Flash Smelting—Continuous flash smelting
technology (Figure 3-5) is used at one domestic smelter with a
capacity of 175,000 tons (159 Gg) per year or 500 tons (454 Mg)
per day of anode copper (based on 350 operating days per year).
Solid wastes at the smelter are slag from the electric slag
treatment furnace, and acid plant blowdown sludge. Copper
content of the slag from the smelting furnace and converters is
too high to discard; therefore it is treated in a small electric
furnace, where some of the copper is liberated as matte. The
cleaned slag is dumped on the land. Slag is generated at a rate
of 2.7 tons per ton of anode copper, or 472,500 tons (429 Gg)
annually at full capacity utilization. Approximately 20,000 tons
(181 Gg) per year is used as railroad ballast (3-24). Blowdown
from the acid plants is pumped to a lined lagoon, where solids
settle and remain. At 100 percent capacity, solids content
amounts to approximately 30 tons (27.2 Mg) per day* or 0.06 ton
per ton of product. Miscellaneous slurries at this plant are
pumped to a lined lagoon where solids settle and are recycled to
the smelter. Based on a 70 percent capacity utilization factor,
the total annual solid waste production at plants represented by
Model 4 is 318,400 tons (288.8 Gg) (Table 3-6).
* Based on a PEDCo engineering estimate from an
industry-supplied value of <<1.0 percent solids in acid plant
blowdown.
3-46
-------
TABLE 3-5
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY COPPER PLANTS
REPRESENTED BY MODEL 3
Waste Annual solid Adjusted annual
generation factor waste production solid waste production
Waste type (tons/ton of product) (tons/year) (tons/year)
Slag
2.2
351,000
351,000
Acid plant
blowdown
0.003
500
500
Miscellaneous
slurries
0.017*
2,700
2,700
Total
354,200
354,200
* Value adapted from: Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refinery industry. 1977.
Note: Metric conversion table is given in front matter.
-------
TO »TWSPWtt
I
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
TO OISPOSAL SITE
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 3-5. In the primary copper industry Model 4 represents plants
with flash smelting.
-------
TABLE 3-6
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY COPPER PLANTS
REPRESENTED BY MODEL 4
Waste type
Waste
'generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Slag
2.7
331,000
311,000
Acid plant
blowdown
0.003
7,400
7,400
Total
338,400
318,400
Note: Metric conversion table is given in front matter.
-------
Model 5: Electrolytic Refining—Twelve domestic
electrolytic refineries with a total annual capacity of 2,450,000
tons (2.2 Tg) produce electrolytic-grade copper of 99.5+ percent
purity from copper anodes (refer to Process Description). A
model plant production rate of 200,000 tons (181 Gg) per year, or
570 tons (517 Mg) per day (based on 350 operating days per year)
was selected to represent the electrolytic refining segment of
the primary copper industry (Figure 3-6). Actual plant output
ranges from 40,000 tons (36.3 Gg) per year to 420,000 tons (381
Gg) per year.
Solid waste production at electrolytic refineries is
negligible in comparison with that generated in smelting because
of the consistently high purity of the input material. Recovery
and recycling techniques are widely practiced to achieve maximum
economic benefit from residuals that are collected.
The only solid wastes from refinery production are dissolved
and suspended solids contained in miscellaneous slurries such as
spent electrolyte, plant washdown water, and contact cooling
water. These slurries are discharged to lagoons or, when an ore
concentrator is nearby, to tailings ponds. Total solids content
of the miscellaneous slurries is 0.002 ton per ton of refined
copper (3-17).
Assuming a worst-case situation in which all refineries are
producing and disposing of solid wastes at this rate and
operating at 65 percent of capacity, the primary electrolytic
3-50
-------
TO ATOSPtCRC
u>
I
ui
I 1
I MILL CONCtNTRATO»|
| | AND TAILINGS POND|
- COPPER
SW.FAU
_ COPPER
STAPTIB SHEETS
- ADDITIVES
SLAG
TO TANK
HOUSE
TO UOOC FURNACE
FOR RECASTING
TO evaporator
I
J EVAPORATOR
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
to melting furnace
liberator cells
muting and
REFINING FURNACE
CASTING
TO SKIKR
OR SOLO
TO melting furnace
OR SKIIUP
NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES.
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 3-6. In the primary copper industry Model 5 represents plants
with electrolylic refining and slimes treatment.
(continued)
-------
I ,
• NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 3-6. (continued)
-------
refineries would generate 3,200 tons (2.9 Gg) of waste material
annually (Table 3-7).
National Solid Waste Totals
Although the waste quantities presented in this study are
based on model plant estimates any available site-specific data
were utilized to adjust the estimates so that they more
accurately reflect the actual quantity of solid waste that is
land-disposed annually by the primary copper smelting and
refining industry. Calculations in this study indicate that the
primary copper smelting and refining industry generated about 3.1
million tons (2.8 Tg) of solid wastes of all types in 1978 (Table
3-8). Slag is by far the largest source of this waste,
accounting for about 99 percent of the 1977 total waste
production. Miscellaneous slurries are the next largest source,
accounting for 0.7 percent of the total; acid plant blowdown and
refinery sludges contributed 0.3 and 0.1 percent respectively.
Most of the solid waste generated by the primary copper
industry is produced in EPA Region IX (Table 3-9).
National Solid Waste Projections
Projected solid waste quantities were estimated in this
report by multiplying the current solid waste generation factors
by the projected marketable copper metal production values for
the years 1980, 1985, and 1990. (Copper metal production values
were obtained from Table 3-1.) This calculation provides the
estimated solid waste projections shown in Table 3-10. These
estimates are based on the following assumptions:
3-53
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TABLE 3-7
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY COPPER PLANTS
REPRESENTED BY MODEL 5
Waste
Annual solid
Adjusted annual
generation factor
waste production
solid waste production
Waste type
(tons/ton of product)
(tons/year)
(tons/year)
Miscellaneous
slurries
0.002*
3, 200
3,200
* Value adapted from: Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refinery industry. 1977.
Note: Metric conversion table is given in front matter.
-------
TABLE 3-8
1978 NATIONAL SOLID WASTE TOTALS FOR THE PRIMARY
COPPER SMELTING AND REFINING INDUSTRY
(tons/year)
Quantity
generated at
plants represented
by:
Waste type
Model 1
Model 2
Model 3
Model 4
Model 5
Total
Slag
1,842,000
605,500
351,000
311,000
3,109,500
Acid plant
blowdown
1,300
450
500
7,400
9,650
Miscellaneous
slurries
16,900
4,700
2,700
3,200
27,500
Total
1,860,200
610,650
354,200
318,400
3,200
3,146,650
Note: Metric conversion table is given in front matter.
-------
TABLE 3-9
GEOGRAPHICAL DISTRIBUTION OF SOLID WASTES FROM THE PRIMARY
COPPER SMELTING AND REFINING INDUSTRY
(1978)
FPA Region
State
Number
of plants
Annual solid
waste production*
(tons/year)
Annual regional
solid waste production
(tons/year)
II
New Jersey
1
350
New York
1
100
450
III
Maryland
1
350
350
IV
Georgia
1
100
Tennessee
1
250
350
V
Michigan
1
136,000
136,000
VI
New Mexico
483,000
Texas
3
2,500
485,500
VII
Missouri
1
50
50
VIII
Montana
2
355,500
Utah
2
354,500
710,000
IX
Arizona
9
1,824,500
Nevada
1 +
71,500
1,896,000
X
Washington
_2 5
1,800
1,800
National
total
28
3,215,500
3,215,500
* Data calculated from model plant values and ad]usted with site-specific data
from PEDCo files.
+ Smelter closed indefinitely in 1978.
§ Refinery closed January 1, 1979.
Note: Metric conversion table is given in front matter.
-------
TABLE 3-10
PROJECTED SOLID WASTE FROM THE PRIMARY COPPER
SMELTING AND REFINING INDUSTRY
Projected solid
(tons/year)
waste
Waste type
1980
1985
1990
Slag
3,271,500
4,487,500
4,976,000
Acid plant
blowdown
12,000
14,500
16,000
Miscellaneous
slurries
27,000
32,500
35,500
Refinery
slurries
3,600
4,300
4,700
Total
3,314,100
4,638,800
5,032,200
Note: Metric conversion table is given in front
matter.
3-57
-------
° The current ratio of reverberatory, electric, Noranda,
and flash smelters remains approximately the same.
° Current solid waste generation factors as developed in
this study for the model plants remain constant.
° The quantity of solid waste produced as a result of
legislation for air and water pollution control will
not change substantially and therefore changes in
future solid waste production will result only from
capacity changes.
Excepting perhaps the one concerning the effects of
pollution control legislation, each of these assumptions is
realistic. The quantity of solid waste going to land disposal in
the future as a result of current and pending environmental
regulations will undoubtedly increase; it is extremely difficult,
however, to estimate the potential quantities of waste because of
the following:
° All regulations of air and water quality have not been
promulgated.
° Current standards for air emissions and liquid
effluents could change and new standards may be
developed.
° Current compliance schedules could change.
° Industry could implement any of several mitigative
approaches to comply with environmental regulations,
and some of these could profoundly affect the
quantities of solid waste going to land disposal.
SCS engineers recently conducted a study to evaluate the
potential impacts of environmental media regulations on land
disposal of solid wastes (3-25). The study addressed the Clean
Air Act of 1970 and the Federal Water Pollution Control Act of
1972, both as amended. In an effort to compensate for the
numerous variables that will affect future solid waste generation
3-58
-------
resulting from environmental regulations, these researchers
estimated future waste quantities by starting with historic data
for 1967 and 1977 as a basis, then projecting a low and a high
value for the years 1980, 1984, and 1987 according to conditions
established in a minimum and maximum scenario (See Appendix B).
The SCS projections are that by 1987 the total sludge generation
in the primary copper industry resulting from air and water
pollution control regulations will be between 645,000 and 757,000
tons (585 and 687 Gg) (Table 3-11). These quantities, which
represent major increases above present conditions, do not
correctly reflect the actual amount of solid waste that will be
going to land disposal in future years as a result of
environmental regulations. First production of copper has not
been factored out of these values, which therefore reflect not
only the increases in sludge generation due to environmental
regulations but also any increases that will result from
increased production. It is also important to note that these
quantities represent sludge generation values and that not all of
the residuals represented by these values will necessarily become
solid waste to be disposed of on the land. For example, a
portion of the sludges reported in Table 3-11 result from
collection of particulates from smelters; yet, since most of
these dusts are recycled for their high metallic content, they do
not represent a solid waste. Another major component of the
total generated sludge in Table 3-11 is acid plant blowdown from
the treatment of strong SC^ gas streams from smelters. Acid
3-59
-------
TABLE 3-11
TOTAL ANNUAL SLUDGE FROM COPPER SMELTING AND REFINING
ATTRIBUTABLE TO AIR AND WATER QUALITY REGULATIONS*
(1000 tons/year dry weight)
Historic
Minimum scenario^
Maximum
scenario
it
Legislation
1967
1977
1980
1984
1987
1980
1984
1987
Water pollution
control act
39.2
56.4
65.9
73.2
85.2
65.9
80.4
86.0
Clean air act
340.6
426.1
452.8
532.8
559.2
543.2
639.4
671.1
Total
379.8
482.5
518.7
606.0
644.4
609.1
719.8
757.1
* SCS Engineers. Comprehensive Sludge Study Relevant to Section 8002(g) of
the Resource Conservation and Recovery Act of 1976 (PL 94-580). EPA Contract No.
68-01-3945. (No date).
^ See Appendix B for explanation of scenarios.
Note: Metric conversion table is given in front matter.
-------
plant blowdown is similar to collected particulates in that a
great deal of it is recycled for metal reclamation and only a
portion constitutes a solid waste.
Generation of sludges from pollution control devices is
expected to increase as more stringent regulations are
implemented to reduce the degradation of air, water, and land;
for the reasons mentioned above, the quantity of waste going to
land disposal as a result of these regulations is not expected to
change substantially. Even if the increase in sludges is greater
than expected, slag will still be by far the largest single
source of solid waste from the primary copper industry and the
relative proportion of solid wastes resulting from environmental
regulations will change only by several percent. The expected
increase will result mainly from neutralization of acid plant
blowdown and scrubbing of weak SC>2 streams from smelters. The
increases should pose no major technological problems, but they
will undoubtedly present some economic burdens to industry.
Qualitative Characteristics of Solid Wastes
The characteristics of furnace slag vary with the
concentrate feed material and with furnace operation. The grade
of matte produced affects the furnace slag, the higher grades of
matte yielding a higher percentage of copper in the slag. Both
Noranda and flash furnaces produce a high grade of matte and both
processes incorporate secondary slag treatment to recovery the
copper. Typical furnace slag analysis appears in Table 3-12.
3-61
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TABLE 3-12
TYPICAL FURNACE SLAG ANALYSIS*
(percent)
Parameter
Plant 1
Plant 2
Plant 3
Plant 4
Plant 5
Pb
0.30
.025
0. 008
0.01
0. 025
Cu
0.56
1. 0
0.61
0.62
0.37
Zn
1.5
. 37
0. 065
0.78
0.80
Sl02
38. 3
Fe
32.6
CaO
5.3
al2o3
4 . 2
S
0.80
Mn02
0.61
MgO
1.79
As
0.17
Sb
0.38
Fe304
29.5
Cd
Trace
Trace
Trace
Trace
Cr
0.005
0.02
0.01
0.005
Hg
Trace
Trace
Trace
Trace
Mn
0.023
0.02
0.05
0.017
Ni
0.001
0.002
0. 003
Trace
Sb
0.025
0.01
0.04
<0.01
Se
0.004
0.002
0.002
0.001
• Value adapted from:
Office of
Solid Waste.
Assessment
of
industrial
hazardous waste
practices
in the metal
smelting and
refining
industry.
1977.
3-62
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Characteristics of acid plant blowdown fluctuate with the
composition of the ore concentrate and with the gas cleaning
operation upstream of the acid plant. Acid plant blowdown is
acidic and usually contains copper, lead, zinc, iron, and
arsenic, among other components. Analysis of acid plant blowdown
from three plants appears in Table 3-13.
Miscellaneous slurries from the smelter and refinery
originate from a variety of sources and their characteristics
vary widely. Slurries from the smelter probably would contain
copper, lead, zinc, iron, arsenic, antimony, and bismuth;
slurries from the refinery would contain these elements plus
sulfuric acid, copper sulfate, and any impurities indigenous to
the ore. Data were not available for characterization of these
slurries.
Evidence indicates that leaching of heavy metals from
electric furnace slag and acid plant blowdown is significant
enough that these wastes are considered hazardous (3-26). The
degree of leaching of other solid wastes from primary copper
plants (slag from reverberatory and Noranda furnaces;
miscellaneous slurries; refinery sludge) is not considered
sufficient to identify these wastes as potentially hazardous
(3-26). In view of these considerations, EPA has listed electric
furnace slag and acid plant sludge as hazardous materials (3-26).
For purposes of this study all other wastes are considered to be
nonhazardous. Because the identification and listing of
3-63
-------
TABLE 3-13
TYPICAL ACID PLANT BLOWDOWN WASTE CHARACTERIZATION*
(lb/ton except as noted)
Parameter
Plant 1
Plant 2
Plant 3
Average
PH
S04 =
Cn"
As
Cd
Cu
Fe
Pb
Hg
Ni
Se
Te
Zn
Oil and
grease
2.0-2.5
1. 99
0.0000
0. 088
0. 004
0.0002
0. 0028
0.0101
0.0000
0.0000
0.0002
0.0000
0.0034
0.0000
1.8
15.45
9.0000
0. 259
0.0028
0.0036
0.0030
0.0284
0.0000
0.0000
0.0000
0. 000
0.420
2.0
128.0
0.0048
0. 008
0.052
276.4
0.2232
0.3002
0.0004
0.0060
0.0536
0.872
0.0
2.0
72.0
0.0016
0.118
0.0194
0.0020
0.0464
0.1796
0.0002
0.0020
0.0180
0.0000
0. 436
0.0
* PEDCo Environmental, Inc., Cincinnati, Ohio. Environmental
Assessment of the Domestic Primary Copper, Lead, and Zinc Industries,
Volume I. EPA Contract No. 68-02-1321, Task No. 38. November, 1976,
3 98 pg.
Note: Metric conversion table is given in front matter.
3-64
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hazardous wastes is only proposed at this time, the above
distinction between hazardous and nonhazardous wastes could
change when the hazardous waste listing is finalized.
Solid Waste Control Practices and Costs
This section describes practices for control of all solid
wastes (hazardous and nonhazardous) generated by primary copper
smelters and refineries, and the associated costs. The first
portion describes current control practices used by the industry.
The costs attributable to the current practices are then
presented. The next subsection deals with alternative control
practices, which provide what are considered to be adequate
environmental safeguards and satisfy the RCRA Criteria. The
costs attributable to these alternative practices are then
estimated. The alternative control systems specified in this
study are based on contractor investigations and on professional
judgment and do not necessarily reflect EPA thinking or policy.
The RCRA Criteria -were used as guidelines in developing the
alternative practices, with consideration for both technical and
economic feasibility. The alternatives are not to be considered
as operational guidelines or standards that industry should be
required to follow; rather, they represent the level of effort
that could be required and the magnitude of cost that could be
incurred. The costs presented for both current and alternative
control systems, are estimates based on a control facility life
of 20 years. The costs are those that would be incurred during
3-65
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the life of the control facility. The cost of closure of
existing facilities for accumulated wastes is also estimated for
the primary copper smelting and refining industry.
The final portion of this section is an analysis of the
solid waste disposal costs. The analysis includes calculation of
the incremental cost that would be incurred by the primary copper
smelting and refining industry through implementation of the
alternative control system and closure of existing waste
facilities. The portions of the incremental cost attributable to
control of nonhazardous and of hazardous solid wastes are.
designated; then the fraction of the incremental cost for
nonhazardous waste control that can be attributed to the RCRA
4004 (nonhazardous waste) Criteria (Criteria-induced cost) is
determined on a state basis. These additional costs attributable
to RCRA for disposal of nonhazardous wastes are compared with
other industry costs incurred in complying with current
regulations for air and water pollution contro^.
Current Solid Waste Control Practices
Current practices for solid waste handling and disposal are
similar throughout the industry. In general, slag is disposed of
on the land, acid plant blowdown (when disposed of) is slurried
to tailings ponds, and miscellaneous slurries are discharged to
lagoons or sent through the mill concentrator circuit.
Historically, selection of the disposal site has been based
on land availability and convenience. Site preparation amounts
3-66
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to clearing the surface of trees and vegetation and removing the
soil to a depth sufficient to form the impoundment. Application
of environmentally sound technologies such as construction of
diversion ditches and monitoring wells, or use of lagoon liners
and soil sealants, has not been prevalent.
Current Control of Slag—At most domestic smelters the
furnace is tapped and the molten slag is transferred to a slag
3 3
pot with capacity of 350 to 450 ft (10 to 13 m ). The slag pot
is transported by rail or rubber-tired vehicle to the slag
disposal area, where the pot is tipped and the slag pours into
the pit. As it cools, the slag solidifies into a rock-like
material. A few smelters practice slag granulation, whereby the
molten slag is sprayed with water as it is poured into the slag
dump. However, stringent effluent guidelines have diminished the
popularity of this practice, and it is not considered as a
current slag disposal method in this analysis.
As noted earlier, at least two smelters have mined their
accumulated slag piles for metal recovery; the tailings from
these operations, however, are ultimately disposed of on the
land. Two other smelters sell their slag to outside contractors
for use as roadfill and aggregate. Slag is used at many
facilities for onsite roadfill, and at some locations where mines
are nearby, it is used as mine backfill. These applications,
however, have minimal impact on the volume of slag disposed of on
land. At plants using the newer, continuous smelting technology,
3-67
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the furnace slag is relatively high in copper and the slag is
treated to recover the copper before disposal (refer to the model
diagrams). In both of these applications, the waste remaining
after copper recovery is land disposed of on the land.
Current Control of Acid Plant Blowdown—As discussed
earlier, very few smelters dispose of acid plant blowdown by
itself. It is used as a flue gas conditioner, returned to the
roaster, or used in the mill concentrator circuit with ultimate
disposal in tailings ponds. The first two methods are actually
recycling technologies and therefore are not included in the cost
analysis. The latter method is a genuine disposal scheme, but no
current costs are developed for disposal in tailings ponds
because the overwhelming volume of tailings so far exceeds the
volume of blowdown sludge that it is unrealistic to allocate any
significant portion of the tailings pond cost to disposal of acid
plant blowdown.
Current Control of Miscellaneous Smelter Slurries—
Miscellaneous smelter slurries are discharged to unlined ponds or
slurried to the mill concentrator if there is one onsite. Eleven
smelters have concentrators onsite; it is assumed that all of
them pump the slurries to the concentrator or tailings thickener,
with ultimate disposal in the tailings ponds. Again, no costs
are developed for this disposal scheme because of the magnitude
of tailings disposed of in these ponds. It is further assumed
that the remaining five smelters discharge the slurries to
3-68
-------
unlined ponds, dredge the solids from the ponds as necessary, and
dispose of them in the slag dump. Overflow from the ponds is
returned to the smelter as process water.
Current Control of Miscellaneous Refinery Slurries—
Miscellaneous refinery slurries are discharged to unlined ponds
or pumped to the mill concentrator. Two electrolytic refineries
are located onsite with mill concentrators, and it is assumed
that both pump the slurry to the concentrator circuit with
ultimate disposal in the tailings ponds. It is also assumed that
the other ten refineries dispose of refinery slurries in unlined
ponds. Because solids buildup is negligible, there is no need
for dredging. Overflow from the ponds is returned to the
refinery as process water.
Costs of Current Controls
Costs of current solid waste control practices are developed
by use of the model plants. The control methods considered in
the analysis represent those used most commonly in the primary
copper smelting and refining industry. Details of the costing
method and the assumptions on which the costs are based are given
in Appendix C. Disposal areas are sized to provide 20 years of
use at current waste generation rates. Capital costs for each
model include those for land, construction, and equipment plus a
10 percent contingency factor. Annual costs are calculated by
amortizing land, construction, and equipment costs, then adding
operating and maintenance costs plus taxes and insurance.
Control costs are computed in dollars per ton of copper produced
3-69
-------
by dividing the capital and annual costs by the annual copper
production at each model plant. The resulting cost factors are
extrapolated to that model plant category of the industry after
adjustments are made for plants that deviate from the model
scenario. The total costs to each model plant category are
summed to yield a total industry cost for current control of
solid wastes.
Current Control Costs for Model 1—Model 1 represents plants
that use reverberatory furnaces to smelt the ore concentrates.
Solid wastes at these plants are furnace slag, acid plant
blowdown, and miscellaneous slurries. Because of the
overwhelming volume of concentrator tailings going to the ponds
no current costs are developed for acid plant blowdown or
miscellaneous slurries when it has been determined that these
residuals are being disposed of in tailings ponds.
A land area of 26 acres (10.5 ha) is designated for disposal
of furnace slag over the course of 20 years, and a land area of
approximately 8 acres (3.2 ha) is designated for impoundment of
miscellaneous slurries. Construction costs for the current
controls include surveying and minimal site preparation for both
disposal areas, a 0.5-mile (0.8-km) rail spur for slag transport,
and an unlined impoundment for miscellaneous slurries.
Equipment costs for the current controls are based on use of
a used industrial yard engine and three ladle cars to transport
furnace slag to the disposal site. Of the total capital cots for
this equipment, 30 percent of that for the yard engine and 100
3-70
-------
percent of that for the ladle cars are allocated to slag dumping.
It is assumed that the yard engine is used in other plant
activities such as transfer of raw materials the remaining 70
percent of the time. Equipment costs for handling and dredging
of miscellaneous slurries include 5 percent of the capital cost
of a dragline and front-end loader and 10 percent of the capital
cost of a 20-ton (18.1-Mg) dump truck, which transports the
dredged solids to the slag dump. A 10 percent contingency fee is
added to all capital costs.
Annual expenses include the amortized cost of land, con-
struction, and equipment and the cost of personnel, maintenance,
utilities, taxes, and insurance. Personnel costs are based on
the quantity and rate of material handled plus a charge for
supervision and fringe benefits. Maintenance charges are based
on the factors listed in Appendix C. Utility charges are
calculated from the number of operating hours and a unit cost of
fuel or electricity. Taxes and insurance are calculated at 2.5
percent of the land cost and 1 percent of the total capital cost
respectively.
The total capital and annual costs of the current solid
waste controls associated with the Model 1 plant are $423,000 and
$192,200 respectively (Table 3-14). These costs are based on a
plant that disposes of all slag on the land and discharges
miscellaneous slurries to unlined ponds. Not all smelters in
this category operate under these conditions, however, and
adjustments must therefore be made for slag that is sold and
3-71
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TABLE 3-14
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 1: REVERBERATORY SMELTING
(1978 dollars)
Slag
dumping
Miscellaneous
slurries
Capital Cost
Land
25,200
7, 500
Construction
Survey
9, 800
2, 900
Site preparation
5, 200
1,500
Rail spur
103,000
Surface impoundment
24,200
Equipment
195,000
10,300
Subtotal
338,200
46,400
Contingency (10%)
33,800
4,600
TOTAL CAPITAL COST
372,000
51,000
423,000
Annual Cost
Land
3,200
1, 000
Construction
15,200
3,100
Equipment
35,000
1, 800
Operation and maintenance
Personnel
92,600
4,700
Maintenance
16,400
1, 500
Fuel and electricity
12,100
500
Taxes
700
200
Insurance
3,700
500
TOTAL ANNUAL COST
178,900
13,300
192,200
3-72
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slurries discharged to tailings ponds. After adjustments are
made for known variations in disposal practices, the total
capital and annual costs to all plants represented by this model
category are $2,149,000 and $1,003,100 respectively. Based on
the total annual production of all plants in this category, the
adjusted installed capital cost is $0,001 per pound ($0,002 per
kg) of copper and the annual cost is $0.0005 per pound ($0,001
per kg) of copper produced.
Current Control Costs for Model 2—Model 2 represents plants
that use electric smelting furnaces. Solid wastes at these
smelters are electric furnace slag, acid plant blowdown sludge,
and miscellaneous slurries. As in the Model 1 calculations, no
costs are developed here for acid plant blowdown or miscellaneous
slurries that are disposed of in tailings ponds.
Costs of controls at Model 2 plants are based on the same
factors described in the analysis of Model 1 costs. The capital
and annual costs of solid waste control at a Model 2 plant are
$419,600 and $175,200 respectively (Table 3-15). These costs are
based on a facility that disposes of all slag on the land and
discharges miscellaneous slurries to unlined ponds. Adjustments
are made for slag that is not disposed of on land and slurries
sent to tailings ponds. After these adjustments, the total
capital costs for all plants in this model category are $789,900
or $0,001 per pound ($0,002 per kg) of copper produced annually
and total annual costs are $329,000 or $0.0006 per pound ($0,001
per kg) of copper produced.
3-73
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TABLE 3-15
TOTAL COST OF SOLID WASTE CONTROLS FOR
MODEL 2: ELECTRIC SMELTING
(1978 dollars)
Slag
dumping
Miscellaneous
slurries
Capital Cost
Land
23,300
7,500
Construction
Sruvey
9,000
2,900
Site preparation
4,800
1,500
Rail spur
103,000
Surface impoundment
24,200
Equipment
195,000
10,300
Subtotal
335,100
46,400
Contingency (10%)
33,500
4,600
TOTAL CAPITAL COST
368,600
51,000 419,600
Annual Cost
Land
3,000
1,000
Construction
15,000
3,100
Equipment
35,000
1,800
Operation and maintenance
Personnel
78,500
4,700
Maintenance
16,400
1,500
Fuel and electricity
10,200
500
Taxes
600
200
Insurance
3,700
300
TOTAL ANNUAL COST
162,400
13,300 175,200
-------
Current Control Costs for Model 3—Solid wastes at a Model 3
smelter (Noranda process) are slag tailings from the slag
concentrator, acid plant blowdown sludge, and miscellaneous
slurries. No costs are included for miscellaneous slurries
because they are used as makeup water for the concentrator.
A land area of 80 acres (32.3 ha) is provided for disposal
of slag tailings for a period of 20 years, and an area of 4 acres
(1.6 ha) is allocated for impoundment of acid plant sludge. The
land area for disposal of slag tailings from Model 3 is greater
than that for the other models because the density of this
tailings material is lower than that of slag that is dumped hot
from the furnace. Construction costs include surveying, minimal
site preparation, an earthen dam for the tailings pond, and an
impoundment for acid plant sludge.
Equipment costs include piping, pumps, a sump, and cyclones
for tailings transport (3-27) and a dump truck and front-end
loader for sludge hauling. Only 1 percent of the capital cost of
the dump truck and front-end loader is allocated to sludge
haulage. A 10 percent contingency fee is added to all capital
expenses.
Annual expenses for the Model 3 plant are developed with the
same factors outlined in analysis of Model 1 (detailed in
Appendix C).
Total capital and annual costs of the current solid waste
controls applicable to the Model 3 plant are $396,300 and
$111,500 respectively (Table 3-16). At an annual production rate
3-75
-------
TABLE 3-16
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 3: NORANDA SMELTING
(1978 dollars)
Capital Cost
Land
Construction
Survey
Site preparation
Impoundment
Equipment
Slag Acid plant
dumping blowdown
77,700
30,000
16,000
51,500
154,100
5,900
2,300
1, 200
20,700
900
Subtotal
Contingency (10%)
TOTAL CAPITAL COST
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and electricity
Taxes
Insurance
TOTAL ANNUAL COST
329,300 31,000
32,900 3,100
362,200 34,100 396,300
10,000 800
12,500 3,100
27,600 200
18,300 1,200
10,200 1,200
20,100 100
2,100 200
3,600 300
104,400 7,100 111,500
3-76
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of 227,500 tons (206 Gg) of copper, capital costs are $0.0009 per
pound ($0,002 per kg) of copper produced annually, and annual
costs are $0.0002 per pound ($0.0005 per kg) of copper.
Current Control Costs for Model 4—Solid wastes from a Model
4 plant (flash smelting) are slag from the electric slag
treatment furnace and acid plant blowdown sludge. Miscellaneous
slurries are impounded in a lagoon, from which solids are
periodically dredged and recycled.
A land area of 36 acres (14.6 ha) is provided for slag
disposal over 20 years, and an area of about 4.5 acres (1.8 ha)
is allocated for impoundment of acid plant sludge. Construction
costs include surveying, minimal site preparation, a 0.5-mile
(0.8-km) haul road for the slag carriers, and a lagoon with liner
and soil cover for receiving the blowdown sludge. [Note: The
actual facility represented by Model 4 has installed a lined
lagoon (3-24).]
Equipment costs include a rubber-tired slag pot carrier,
three slag pots, and a dragline, front-end loader, and dump truck
for periodic transfer of blowdown solids to the slag dump area.
Ten percent of the capital cost of the dredge and front-end
loader, and 15 percent of the capital cost of the dump truck are
attributed to sludge transfer. A 10 percent contingency charge
is added to all capital costs.
Annual expenses for Model 4 are based on the factors
outlined for Model 1 and detailed in Appendix C.
3-77
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The total capital and annual costs of the current solid
waste control system applicable to the Model 4 plant are $264,800
and $138,900 respectively (Table 3-17). At an annual production
rate of 175,000 tons (159 Gg) of copper, capital costs are
$0.0008 per pound ($0,002 per kg) of copper produced annually,
and annual costs are $0.0004 per pound ($0.0009 per kg) of
copper.
Current Control Costs for Model 5—The solid wastes from a
Model 5 plant representing electrolytic refineries, are the
solids in miscellaneous plant slurries such as cooling water and
plant washdown water, and spent electrolyte. No costs are
allocated to slurries that are recycled to the mill concentrator.
A land area of 6 acres (2.4 ha) is provided for impoundment
of miscellaneous slurries for a 20-year period without dredging.
Construction costs include surveying, minimal site preparation,
and formation of the impoundment. Equipment costs are limited to
a sump, pump, and piping. A 10 percent contingency fee is added
to all capital costs.
Annual expenses are based on the factors outlined in
analysis of Model 1 and used in analysis of all five models
representing copper smelting and refining operations.
The total capital cost of the current solid waste control
system at the Model 5 plant is $36,500, or $0.00009 per pound
(0.0002 per kg) of refined copper produced annually. Total
annual costs of the current system are $6,100, or $0.00002 per
3-78
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TABLE 3-17
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 4: FLASH SMELTING
(1978 dollars)
Slag
dumping
Acid plant
blowdown
Capital Cost
Land
35,000
4,300
Construction
Survey
13,500
1,700
Site preparation
7,200
900
Haul road
15,600
Liner
64,300
Soil cover
15,800
Surface impoundment
15,800
Equipment
47,500
19,100
Subtotal
118,800
121,900
Contingency (10%)
11,900
12,200
TOTAL CAPITAL COST
130,700
134,100
264,800
Annual Cost
1
Land
4,500
600
Construction
4,700
12,700
Equipment
8,500
3,400
Operation and maintenance
Personnel
64,600
17,100
Maintenance
3,500
6,000
Fuel and electricity
7,600
2,000
Taxes
1,000
100
Insurance
1,300
1,300
TOTAL ANNUAL COST
95,700
43,200
138,900
3-79
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pound ($0.00004 per kg) of refined copper. Total capital and
annual costs to all plants represented by Model 5 are $255,000
and $42,500 respectively (Table 3-18).
Total Cost of Current Controls—The total capital cost to
the smelting segment of the industry (Models 1-4) incurred in
current solid waste control is estimated to be $3.6 million, or
$0,001 per pound ($0,002 per kg) of industry output at 70 percent
of copper-producing capacity (Table 3-19). The total capital
costs to refineries (Model 5) are $255,000 or $0.00009 per pound
($0.0002 per kg) of refined copper.
The total annual cost to the smelters of the current
controls is $1.6 million or $0.0005 per pound ($0,001 per kg) of
copper produced. The total annual cost to refineries is $42,500
or $0.00002 per pound ($0.00004 per kg) of refined copper.
The current control practices therefore entail a total
capital cost of $0,001 per pound ($0,003 per kg) of copper that
undergoes both smelting and electrolytic refining. The total
annual cost for each ton of copper from smelting through refining
is $0.0005 per pound ($0,001 per kg). The estimated annual
current disposal cost, based on 3.1 million tons (2.8 Tg) of
solid waste generated per year, is $0.52 per ton ($0.57 per Mg)
of solid waste.
Alternative Solid Waste Control Practices
This section proposes alternative methods of solid waste
disposal that are judged to provide sufficient environmental
safeguards. The practices are intended to protect human health
3-80
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TABLE 3-18
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 5: ELECTROLYTIC REFINING
Miscellaneous
slurries
Capital Cost
'Land
Construction
Survey
Site preparation
Surface impoundment
Equipment
Subtotal
Contingency (10%)
TOTAL CAPITAL COST
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Maintenance 900
Fuel and electricity 100
Taxes 200
Insurance 400
TOTAL ANNUAL COST 6,100
5, 900
2,300
1, 200
20,700
3,100
33,200
3,300
36,500
800
3,100
600
3-81
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TABLE 3-19
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR THE
PRIMARY COPPER SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 2,149,000 1,003,100
Model 2 789,900 329,000
Model 3 369,300 111,500
Model 4 264,800 138,900
Model 5 255,000 42,500
Total 3,855,000 1/625,000
3-82
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and to eliminate potential contamination of air and water. These
practices consist of relatively intensive site selection,
extensive site preparation, ground sealing, a leachate collection
system, runoff collection and diversion ditches, wells for
monitoring of groundwater, flood dikes, fencing, closure of
disposal sites, and postclosure monitoring and maintenance. Such
control practices are rarely followed in current disposal
operations. Although, in the alternative system it is assumed
that the controls are extensively used, they may not actually be
necessary at each site. For example, leachate collection may not
be necessary in areas where groundwater levels are low or where
natural soil formations limit the possibility that seepage will
reach groundwater. Important constituents of the alternate
controls that are common to all situations are relatively
intensive site selection, groundwater monitoring, site closure,
and postclosure monitoring and maintenance.
The site selection process involves the following
considerations: topography; soil type, including the chemistry
and permeability of surface and underground soils; availability
of land for expansion; long-range land use; sensitivity of the
environment; and aesthetics. A site selection process of this
scope will increase disposal costs but will minimize long-term
adverse effects. The alternative control scheme provides for
more intensive site preparation, which includes clearing and
grubbing the area, as in current controls, as well as removing
the top few inches of soil and grading the site.
3-83
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A seepage collection system of drainage tiles is installed
under the disposal area to collect any seepage from the site. An
impervious soil-cement pad 6 in. (0.15 m) thick is installed over
the drainage bed to prevent waste-pile leachate from entering the
ground. The collection system is also used to check the
integrity of the soil-cement pad (or synthetic liner) by
monitoring the quantity of collected seepage — an increase in
the quantity could indicate a rupture in the ground seal. Runoff
from adjacent land areas is diverted around the site by ditches
located on the upgradient side of the disposal area; runoff from
the site proper is collected in ditches on the downgradient side
of the disposal site. Collected runoff and seepage flow to a
common sump, from which they are pumped for use as process water
or for treatment and disposal.
Groundwater monitoring is designed to detect contamination
from solid waste disposal. The system includes six monitoring
wells 100 ft (30 m) deep within the plant line. (The Model 5
plants use only three wells because less land is needed for waste
disposal at these plants). At least one well is to be installed
hydraulically upgrade from the disposal site to provide
background data on groundwater quality. Two wells are installed
immediately adjacent to and hydraulically downgrade of the
disposal site. Two of the remaining three wells are installed
within the property line hydraulically downgrade of the disposal
site. The sixth well is situated wherever desired (within the
plant line) to monitor groundwater.
3-84
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The alternative controls call for security fencing around
the perimeter of the disposal area to limit access by
unauthorized persons. It also includes an allowance at 25
percent of the plant sites for diking to protect against
flooding. Because 25 percent of the smelting segment of the
industry amounts to four plants, three reverberatory smelters and
one electric smelter are designated for flood control diking and
appropriate costs are included.
Closure of a disposal site at the end of its useful life is
required under recently proposed (hazardous waste) regulations
and will probably be required for both hazardous and nonhazardous
solid wastes. Site closure in this approach consists of covering
the wastes with soil and revegetating the soil cover to prevent
erosion. The bottom cover layer is a soil having low
permeability to minimize water seepage into the discarded waste;
the upper layer is topsoil capable of supporting indigenous
vegetation. Total thickness of the cover is 2 feet (0.6 m). To
ensure that funds will be available at the time of site closure,
a trust fund is established before the site is opened.
The proposed regulations also require postclosure monitoring
and site maintenance for 20 years after closure. Monitoring of
groundwater and leachate involves periodic collection and
analysis of samples from the onsite wells and the seepage
collection system. Postclosure site maintenance consists of
primarily maintaining the soil cover, vegetation, monitoring
3-85
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wells, and security fencing. Again, a trust fund to provide the
required capital is established before the site is opened for
waste disposal.
Alternative Control of Slag—Alternative slag control
practices incorporate more intensive site selection and site
preparation, as described above. During construction, added
measures are taken to eliminate groundwater seepage and surface
water runoff by placing a soil-cement pad and transverse drain
field under the disposal area, and by forming diversion and
collection ditches both upgrade and downgrade of the site.
Details of the soil-cement pad and drainfield are in Appendix C.
Monitoring wells 100 feet (30-m) deep are installed to
detect seepage and groundwater contamination. Security fencing
is placed around the perimeter of the site, and flood dikes are
included at 25 percent of the facilities.
After a life of 20-years the site is closed by covering the
slag with soil and revegetating the surface to prevent erosion.
Allowances are made for monitoring and maintenance of the site
for a period of 20 years after closure.
Alternative Control of Acid Plant Blowdown—Because acid
plant blowdown contains hazardous metals, disposal in tailings
ponds is not considered adequate for protection of the
environment because of the potential for seepage and groundwater
contamination. The alternative system therefore proposes that
acid plant blowdown be placed in lined impoundments.
3-86
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The acid plant blowdown controls include the more intensive
site selection and preparation just described. Again, provisions
are made to eliminate groundwater seepage and contamination by
installing a transverse drain field, synthetic liner, and soil
cover. Monitoring wells are installed to detect seepage, and to
alert the operators of any malfunctions. The impoundment is also
secured with fencing. The lagoon dike is assumed to be high
enough to provide for adequate flood protection and therefore no
additional diking is necessary. Portions of the closure and
postclosure activities at the slag disposal area are attributable
to acid plant blowdown controls because the solids are
periodically dredged from the impoundment and transferred to the
slag disposal site.
Alternative Control of Miscellaneous Smelter Slurries--
Disposal of miscellaneous slurries in tailings ponds is not
considered environmentally sound because of the dangers of
leaching and comingling of wastes. The alternative practice
allows for disposal of the slurries in lined impoundments.
Again, the alternative practices for controlling
miscellaneous slurries include the more intensive site selection
and preparation; installation of a transverse drain field,
synthetic liner, and soil cover; installation and use of
monitoring wells; security fencing. The dike around the lagoon
is assumed to be high enough to provide for adequate flood
protection. Further, because solids from the slurries are
periodically dredged and transferred to the slag disposal site,
3-87
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portions of the closure and postclosure activities for the slag
disposal area are attributable to control of miscellaneous
slurries.
Alternative Control of Miscellaneous Refinery Slurries—
As with other slurries, disposal of miscellaneous refinery
slurries in tailings ponds is not considered environmentally
sound. The alternative controls therefore propose disposal of
all miscellaneous refinery slurries in lined impoundments as
described above. Other aspects of alternative control also are
as just described.
Costs of Alternative Controls
Costs of alternative solid waste controls for the industry
are developed with the model plant approach. Disposal areas are
sized to allow for 20 years of use at current waste generation
rates.
Capital costs for the alternative controls include those for
site selection, land, construction, equipment, closure, and
postclosure operations. Costs of site selection, installation of
monitoring wells, and sampling and analysis are divided equally
among waste types. Capital costs for security fencing are
allocated on the basis of the relative capital cost of the land
required for each waste disposal area.
Although costs developed for closure and postclosure
operations are attributable to all wastes in each model plant,
they are attributed in the analysis only to slag disposal. This
is done for two reasons. First, it is assumed that solids from
3-88
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the slurry and blowdown impoundments are periodically dredged and
transferred to the slag disposal area for permanent disposal;
second, the costs of closure and postclosure operations at the
blowdown and slurry disposal areas, amount to less than 1 percent
of the total closure and postclosure costs on the basis of waste
volume.
A 15 percent contingency factor is added to the total
capital cost.
Annual costs include amortization of costs of site
selection, land, construction, equipment, closure, and
postclosure operations plus personnel, maintenance, utilities,
and sampling and analysis. Taxes and insurance were based on 2.5
percent of the land capital cost and 1 percent of the total
capital cost respectively.
The capital and annual costs predicted by use of the model
plants are extrapolated to all plants in each model category
after adjustments are made for those not needing flood
protection. Then the total costs to all plants within the model
category are divided by the total annual production of those
plants to yield cost factors for each pound of copper produced.
Alternative Control Costs for Model 1—Costs of the
alternative controls are developed here for Model 1 plants
representing reverberatory smelting.
Site selection is one of the most important differences
between current and alternative practices. The costs consist of
the cost of 1 engineer-year and the cost of a hydrogeological
3-89
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survey and report covering three potential disposal sites. The
total cost of site selection is estimated to be $59,800, divided
equally among the waste types in the model.
The land area for slag disposal is increased by 20 percent
over the current disposal area to allow space for pumps,
monitoring wells, and ditching. The land area required for slag
disposal over a 20-year life is 31 acres (13 ha). Land
requirements for impoundment of acid plant blowdown and
miscellaneous slurries are 1.6 acres (0.6 ha) and 7.7 acres (3
ha) respectively.
The capital costs of construction that are applicable to
each of the disposal sites are surveying, intensive site
preparation, installation of monitoring wells, and security
fencing. Additional construction costs attributable to the slag
disposal area are a rail spur forslag transport, a soil-cement
pad 6 in. (0.15 m) thick, a perforated transverse drain field,
and collection and diversion ditching upgradient and downgradient
of the disposal site at a length 1.5 times the length of one side
of the site.
It is assumed that flood control dikes around slag disposal
areas are also needed at 25 percent of the facilities.
Additional construction costs applicable to both the slurry and
blowdown impoundments are a perforated transverse drain field, a
-4
synthetic liner, 30 mils (7.6 x 10 m) thick, an 18-m. (0.5-m)
soil cover, and costs attributable to formation of the
3-90
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impoundment. It is assumed that the impoundment dikes provide
adequate flood protection.
Equipment costs for slag transport are the same as those
incurred in current practice. Equipment costs for disposal of
miscellaneous slurries and acid plant blowdown are based on time
needed to dredge the solids and transport them to the slag
disposal area.
Site closure costs include excavation and placement of a
soil cover 2 ft (0.6 m) deep on the solid waste pile. The bottom
6 inches (0.15 m) of soil are compacted to reduce permeability
and limit the seepage of water into the wastepile. The soil
cover is fine graded and revegetated for stabilization. Costs of
regrading the waste pile to a gentle slope to reduce erosion is
not included because it is assumed that the wastes are dumped so
that regrading is not necessary.
One of the most significant costs of the alternative
controls is for postclosure monitoring and maintenance.
Monitoring, which includes sampling and analysis of groundwater
and leachate from the disposal site, is continued for 20 years
after site closure. Maintenance of the groundwater monitoring
wells, the drain system under the site, the soil cover, the
vegetation, and the fence around the site also continues for 20
years after closure.
Annual expenses include the amortized cost of land,
construction, equipment, closure, and postclosure operations, and
the cost of personnel, maintenance, utilities, taxes, and
3-91
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insurance. As in the costing of current controls, the factors
described in Appendix C are applied: personnel costs are based
on the quantity and rate of material handled plus cost of
supervision and fringe benefits; maintenance charges are based on
the specified factors; utility charges are based on operating
hours and unit costs; taxes and insurance are 2.5 percent of the
land cost and 1 percent of the total capital cost respectively.
The total capital and annual costs of the alternative
controls associated with the Model 1 plant are $1,857,100 and
$423,300 respectively (Table 3-20). Before calculation of total
costs to plants in this model category, adjustments are made for
those that do not need flood protection. With these adjustments,
the total capital costs to all plants in this model category are
$12,459,500 or $0,006 per pound ($0,014 per kg) of copper. Total
annual costs to all plants in this model category are $2,925,500
or $0.0015 per pound ($0,003 per kg) of copper.
Alternative Control Costs for Model 2—Model 2 represents
plants that use electric smelting. Development of costs of
alternative controls involves factors and procedures identical to
those just described for Model 1.
The total capital and annual costs of alternative controls
associated with the Model 2 plant are $1,781,900 and $406,500
respectively (Table 3-21). After adjustments for plants not
requiring flood protection, the total capital costs to all plants
in this model category are $3,396,000 or $0,006 per pound ($0,013
per kg) of copper. Total annual costs to all plants in this
3-92
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TABLE 3-20
COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 1: REVERBERATORY SMELTING
(1978 dollars)
Slag
Acid plant
Miscellaneous
dumping
blowdown
slurries
Capital Cost
Site selection
19,900
19,900
19,900
Land
30,100
1,600
7,500
Construction
Survey
11,600
600
2,900
Site preparation
16,400
800
4,100
Rail spur
103,000
Soil cement
212,000
Drain field
53,200
7,400
16,400
Ditching
14,500
Synthetic liner
28,900
112,700
Soil cover
7,100
27,600
Monitoring wells
5,500
5, 500
5, 500
Flood dikes
85,200
Fencing
55,100
2,900
13,700
Surface impoundment.
13,400
24,200
Equipment
195,000
4,600
10,300
Closure operations
192,900
Postclosure operations
283,000
Subtotal
1,277,400
92,700
244,800
Contingency (15%)
191,600
13,900
36,700
TOTAL CAPITAL COST
1,469,000
106,600
281,500 1, 857,1C
Annual Cost
Site selection
2,700
2,700
2, 700
Land
4,000
200
1,000
Construction
74,900
8,200
28,500
Equipment
36,600
900
1,900
Operation and maintenance
Personnel
92,600
800
4,700
Maintenance
39,400
3,200
10,400
Fuel and electricity
12,200
100
500
Sampling and analysis
6,700
6,700
6, 700
Closure operations
26,000
Postclosure operations
38,100
Taxes
900
100
200
Insurance
14,700
1,100
2,900
TOTAL ANNUAL COST
348,800
24,000
59,500 432,30
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TABLE 3-21
COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 2: ELECTRIC SMELTING
{1978 dollars)
Slag
dumping
Acid plant
blowdowrt
Miscellaneous
slurries
Capital Cost
Site selection
19,900
19, <50'
J 9,900
Land
28,200
] ,0tK'
1 , 500
Construction
Survey
10,900
60o
2,900
Site preparation
15,400
8c:
4,100
Rail spur
103,000
Soil cement
197,500
Drain field
48,700
7,400
16,400
Ditching
13,900
Synthetic liner
28,900
112,700
Soil cover
7,100
27,600
Monitoring wells
5,500
5,500
5, 500
Flood dikes
82,600
Fencing
53,000
3, 000
14,000
Surface impoundment
13,400
24,200
Equipment
195,000
4,600
103,000
Closure operations
161,000
Postclosure operations
277,000
Subtota1
1,
,211,600
92,800
245,100
Contingency (15%)
181,700
13,900
36,800
TOTAL CAPITAL COST
1,
,393,300
106,700
281,900 1,781,90
Annual Cost
Site selection
2,700
2,700
2,700
Land
3,800
200
1,000
Construction
72,800
8,400
26,900
Equipment
36,600
900
1, 900
Operation and maintenance
Personnel
78,500
800
4,700
Maintenance
39,600
3,200
10,400
Fuel and electricity
10,300
100
500
Sampling and anlaysis
6,700
6, 700
6,700
Closure operations
21,700
Postclosure operations
37,300
Taxes
800
100
200
Insurance
13,900
1,100
2,800
TOTAL ANNUAL COST
342,700
24,000
57,800 406,5C
3-94
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model category are $687,400 or $0.0012 per pound ($0,003 per kg)
of copper.
Alternative Control Costs for Model 3—Costing of
alternative controls for Model 3 parallels that of Models 1 and
2. An exception is the greater amount of land required for
disposal of the lower-density tailings material. The land area
required for slag disposal over a 20-year life is 96 acres (39
ha). Land requirements for impoundment of acid plant blowdown
and miscellaneous slurries are 6 acres (2.4 ha) and 9 acres (3.6
ha) respectively.
The total capital and annual costs of alternative controls
associated with the Model 3 plant are $3,230,600 and $572,400
respectively (Table 3-22). Because there is only one plant in
this model category, costs are equated to plant production
without adjustments. Capital costs are $0,007 per pound ($0,016
per kg) of annual production of copper, and annual costs are
$0.0013 per pound ($0,003 per kg) of copper.
Alternative Control Costs for Model 4--At the Model 4 plant
the solids contained in miscellaneous plant slurries are
currently recycled; and consequently no costs are developed here
for disposal of this waste. The land area required for slag
disposal over 20 years is 43 acres (17 ha). Land requirements
for impoundment of acid plant blowdown are 4.5 acres (1.8 ha).
In other respects the development of costs of alternative
controls is the same as that described for Model 1.
3-95
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TABLE 3-22
COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 3: NORANDA SMELTING
(1978 dollars)
Slag Acid plant Miscellaneous
dumping blowdown slurries
Capital Cost
Site selection
19,000
19,900
19, 900
Land
93,200
5,900
8,700
Construction
Survey
36,000
2,300
3,400
Site preparation
50,900
3,200
4, 800
Soil cement
658,200
Drain field
148,900
10,700
21,000
Ditching
16,900
Synthetic liner
81,900
160,700
Soil cover
20,100
39,400
Monitoring wells
5, 500
5, 500
5,500
Fencing
76,100
4, 800
7,100
Surface impoundment
97,500
20,700
34,500
Equipment
154,100
900
7,100
Closure operations
582,000
Postclosure operations
382,000
Subtotal
2,321,200
175,900
312,100
Contingency (15%)
348,200
26,400
46,800
TOTAL CAPITAL COST
2,669,400
202,300
358,900
Annual Cost
Site selection
2,700
2,700
2,700
Land
12,500
800
1,200
Construction
145,900
19,200
37,000
Equipment
28,900
200
1,300
Operation and maintenance
Personnel
18,300
1,200
5,100
Maintenance
64,000
7, 300
15,000
Fuel and electricity
20,100
200
800
Sampling and analysis
6, 700
6,700
6, 700
Closure operations
78,300
Postclosure operations
51,400
Taxes
2,700
200
300
Insurance
26,700
2, 000
3, 600
TOTAL ANNUAL COST
458,200
40,500
73,700
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The total capital and annual costs of alternative controls
associated with the Model 4 plant are $1,601,300 and $355,100
respectively (Table 3-23). Because there is only one plant in
this category, costs are equated to production without
adjustments. Capital costs are $0,005 per pound ($0,010 per kg)
of copper produced annually; annual costs are $0,001 per pound
($0,002 per kg) of copper produced.
Alternative Control Costs for Model 5—Cost of some of the
alternative controls for Model 5 are lower than those for the
other models because electrolytic refineries generate less waste.
The total cost of site selection is estimated to be $30,000,
which is divided equally among the waste types in the model.
Land area required for the slurry impoundment is 6 acres (2.4
ha).
The total capital and annual costs of alternative controls
associated with the Model 5 plant are $431,000 and $69,400
respectively (Table 3-24). Total capital costs to all plants in
this model category are $5,292,000 or $0,001 per pound ($0,002
per kg) of copper refined annually. Total annual costs to all
plants in this category are $857,500 or $0.0002 per pound
($0.0004 kg) of copper refined.
Total Costs of Alternative Controls—The total capital cost
to the smelting segment of the industry (models 1-4) that is
incurred in alternative controls is estimated to be almost $21
million, or $0,006 per pound ($0,014 per kg) of industry output
at 70 percent of copper-producing capacity (Table 3-25). The
3-97
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TABLE 3-23
COST'OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 4 : FLASH SMELTING
(1978 dollars)
Slag Acid plant
dumping blowdown
Capital Cost
Site selection
Land
Construction
Survey
Site preparation
Haul road
Soil cement
Drain field
Ditching
Synthetic liner
Soil cover
Monitoring wells
Fencing
Surface impoundment
29,900
41,800
16,100
22,800
15,600
296,200
74,000
17,000
8, 300
81,300
29,900
4 , 300
1, 700
900
10,500
64,300
15,800
8,300
4, 300
15,800
Equipment
Closure operations
Postclosure operations
47,500
263,100
304,000
19,100
Subtotal
Contingency (15%)
1,217,600
182,600
174,900
26,200
TOTAL CAPITAL COST
1,400,200
201,100 1,601,300
Annual Cost
Site selection 4,000
Land 5,600
Construction 70,300
Equipment 8,900
Operation and maintenance
Personnel 64,600
Maintenance 30,700
Fuel and electricity 7,700
Sampling and analysis 10,000
4 , 000
600
15,300
3,400
17,100
7,200
2,100
10,000
Closure operations 34,400
Postclosure operations 40,900
Taxes 1,200 100
Insurance 14,000 2,000
TOTAL ANNUAL COST 293,300 61,800 335,100
3-98
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TABLE 3-24
COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 5: ELECTROLYTIC REFINING
(1978 dollars)
Miscellaneous
slurries
Capital Cost
Site selection 30,000
Land 5,900
Construction
Survey 2,3 00
Site preparation 3,200
Drain field 14,000
Synthetic liner 80,500
Soil cover 19,700
Monitoring wells 8,300
Fencing 23,600
Impoundment 20,700
Equipment 3,100
Closure operations 38,200
Postclosure operations 126,000
Subtotal 375,500
Contingency (15%) 56,300
TOTAL CAPITAL COST 4 31,800
Annual Cost
Site selection 4,000
Land 800
Construction 22,100
Equipment 600
Operation and maintenance
Maintenance 8,800
Fuel and electricity 100
Sampling and analysis 10,000
Closure operations 3,800
Postclosure operations 14,700
Taxes 200
Insurance 4,300
TOTAL ANNUAL COST 6 9,400
3-99
-------
TABLE 3-25
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR THE
PRIMARY COPPER SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 12,459,500 2,925,500
Model 2 3,396,000 687,400
Model 3 3,230,600 572,400
Model 4 1,601,300 355,100
Model 5 5,292,000 857,500
Total 26,279,400 5,397,900
3-100
-------
total capital costs to refineries (Model 5) are $5.3 million, or
$0,001 per pound ($0,002 per kg) of refined copper.
The total annual cost to the smelters is $4.5 million or
$0,001 per pound ($0,003 per kg) of copper produced. The total
annual cost to refineries is $857,500 or $0.0002 per pound
($0.0004 per kg) of refined copper.
The alternative controls therefore require a total capital
cost of $0,007 per pound ($0,016 per kg) of copper that undergoes
both smelting and electrolytic refining. The total annual cost
for each ton of copper, from smelting through refining, is
$0.0012 per pound ($0,003 per kg). The estimated annual disposal
cost, based on 3.1 millions of waste generated per year, is $1.70
per ton ($1.90 per Mg) of solid waste.
Cost of Closing Existing Solid Waste Control Sites
All copper plants currently have onsite areas for solid
waste disposal. These disposal sites contain some or all of the
solid wastes described earlier. The current and past practices
for solid waste control at these disposal sites may not provide
adequate protection of human health and the environment according
to RCRA standards; therefore, these sites may be declared open
dumps, and operators will be required to close or upgrade them.
For this study it is assumed that all existing onsite
disposal areas fail to meet RCRA criteria, that these sites will
be closed rather than upgraded to meet RCRA requirements, and
that new onsite disposal facilities that comply with RCRA
standards will be constructed. The costs of closure for existing
3-101
-------
sites are estimated to determine the potential capital and annual
cost that may eventually be incurred by the copper industry.
The total volume of wastes accumulated at the sites is
estimated on the basis of average plant age and solid waste
generation factors. Closure costs are based on covering the slag
pile with 2 ft (0.61 m) of soil, compacting the first 6 in. (0.15
m), and grading and vegetating the soil cover. Unit costs for
these activities are: excavation and placement of cover, $1.60
3 3 3 3
per yd ($1.22 per m ); compaction, $2.14 per yd ($1.63 per m );
2 ?
grading, $0,065 per ft ($0,006 per m ); and vegetating, $1,000
per acre ($2,470 per ha).
The total estimated capital cost to the industry of closing
the existing disposal sites is approximately $7 million, and the
total annualized cost is $825,000 (Table 3-26).
Analysis of Solid Waste Control Costs
The cost analysis presented in this section includes the
calculation of the total incremental solid waste control costs
that would be incurred by the copper smelting and refining
industry by implementing the alternative control practices and
closing the disposal sites that contain waste accumulated to date
(Table 3-27). The total incremental control cost is given in
terms of nonhazardous and hazardous wastes. Wastes classified as
hazardous are electric furnace slag and acid plant blowdown
(3-26). The total incremental cost of controlling nonhazardous
waste represents 84 percent of the total incremental cost of
solid waste control.
3-102
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TABLE 3-26
TOTAL COST OF CLOSING EXISTING DISPOSAL SITES FOR THE
PRIMARY COPPER SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by:
Capital
Annual
Model
1
4,450,000
520,000
Model
2
1,755,000
204,000
Model
3
75,600
8,800
Model
4
107,800
12,600
Model
5
680,500
79,600
Total
7,068,900
825,000
3-103
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TABLE 3-27
CURRENT, ALTERNATIVE, CLOSURE, AND INCREMENTAL CONTROL COSTS FOR THE
PRIMARY COPPER SMELTING AND REFINING INDUSTRY
(1978 dollars)
Current Alternative* Closure5 Incremental11
Waste type* Capital Annual Capital Annual Capital Annual Capital Annual
Nonhazardous^ 2,996,500 1,269,500 22,349,400 4,448,900 5,313,900 621,000 24,666,800 3,800,400
Hazardous** 858,500 355,500 3,930,000 949,000 1,755,000 204,000 4,826,500 797,500
Total 3,855,000 1,625,000 26,279,400 5,397,900 7,068,900 825,000 29,493,300 4,597,900
w * Classification of solid waste as hazardous or nonhazardous is based on EPA's listing of
f—1
O hazardous waste in the December 18, 1978, Federal Register (43 Fed. Reg. 58946).
* Alternative control costs include the cost of the alternative controls together with the cost
of closing and maintaining the alternative disposal sites.
5 Closure costs represent the cost of closing existing solid waste disposal sites.
' Incremental costs equal the sum of the cost of alternative controls and cost of closure minus
the costs of current controls.
@ Nonhazardous wastes are reverberatory slag, Noranda slage tailings, flash furnace slag,
miscellaneous smelter and refinery slurries.
** Hazardous wastes are electric furnace slag and acid plant sludge.
-------
In estimating the fraction of the incremental cost of
nonhazardous waste control that can be attributed to the RCRA
Criteria, one must consider both state-standard-induced cost
(cost of complying with current state regulations) and
Criteria-induced cost.
The Criteria-induced costs are the incremental control costs
that cannot be attributed to state regulations. The coverage of
state regulations was determined from an analysis of state
regulations and the proposed Federal Criteria (3-28).
The major costs to the copper industry that are potentially
attributable to the Criteria are those relating to
environmentally sensitive areas (flood plains), surface water,
groundwater, and safety (access). Costs of closure and
postclosure maintenance of facilities containing waste
accumulated to date and facilities used in alternative controls
cannot be directly attributed to any one criterion but are
indirectly attributable to all. For purposes of this study all
closure costs are assumed to be attributable to the Criteria.
Criteria considered as inapplicable to this industry are those
dealing with wetlands, permafrost, critical habitat, and
sole-source aquifers (all considered as environmentally
sensitive); air; disease vectors; explosive gases, fires, toxic
gases, and bird hazards (aspects of safety).
The Criteria-induced costs consist of those for closure and
postclosure operations of alternative disposal sites in all
states, closure of existing sites in all states, groundwater
3-105
-------
protection in Utah, and fencing (access) in Arizona, New Jersey,
and Utah. With one exception, no costs are allocated to flood
plain protection because states in the arid western states are in
minimal danger of flooding. Where flooding may be a problem, the
state regulations are adequate, or if there are no regulations
the impoundment dike provides protection against inundation by
flood waters. The cost of the impoundment, however is considered
here only as construction cost and is not attributable to flood
protection. The sole exception is the State of Michigan, for
which the costs of protection against flooding of the slag dump
are included.
The Criteria-induced capital cost for the primary copper
smelting and refining industry is $12.5 million (Table 3-28), or
$5.92 per ton ($6.53 per Mg) of capacity, representing 51 percent
of the total incremental capital cost of controlling nonhazardous
waste from Table 3-27. The Criteria-induced annual cost of $1.6
million, or $1.32 per ton ($1.45 per Mg) of copper, is 43 percent
of the total incremental annual cost.
As a point of reference, it has been estimated that capital
expenditures (in 1975 dollars), still required to bring existing
plants into compliance with air and water quality regulations
amount to $444 per ton ($489 per Mg) of capacity, of which $371
per ton ($409 per Mg) is for compliance with air regulations and
$73 per ton ($80 per Mg), for water. As further reference, the
estimated capital cost of a copper mine-mill-smelter complex is
$6,000 per annual ton ($6,600 per Mg) in 1975 dollars (3-29).
3-106
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TABLE 3-28
CRITERIA-INDUCED CONTROL COSTS FOR PRIMARY COPPER
SMELTING AND REFINING INDUSTRY*
(1978 dollars)
State
Capital
Annual
Arizona
5,707,800
731,800
Georgia
78,900
9, 000
Maryland
301,500
34,400
Michigan
484,400
61,100
Missouri
47,700
5,400
Montana
596,700
68,800
Nevada
133,500
15,600
New Jersey
344,700
41,600
New Mexico
1,209,900
155,500
New York
78,900
9,000
Tennessee
0
0
Texas
923,000
105,500
Utah
2,540,300
391,300
Washington
43,600
5,100
Total
12,490,900
1,634,100
* These values include additional costs for closure
of accumulated nonhazardous solid waste, closure and post-
closure maintenance of alternative nonhazardous solid waste
systems, and Criteria-induced costs for states whose solid
waste regulations do not satisfy the Criteria.
3-107
-------
The costs projected in this study indicate that the
Criteria-induced costs are several orders of magnitude lower than
the costs required for compliance with air and water quality
regulations in the primary copper smelting and refining industry.
3-108
-------
REFERENCES FOR SECTION 3
3-1. Schroeder, H.J. Copper Mineral Commodity Profile - 3.
U.S. Department of the Interior, Bureau of Mines,
Washington, D.C. June 1977.
3-2. Draft of Standards Support and Environmental Impact
Statement. Vol. 1: Proposed National Emission Standards
for Arsenic Emissions from Primary Copper Smelters.
U.S. Environmental Protection Agency, Office of Air and
Waste Management, Office of Air Quality Planning and
Standards, Research Triangle Park, North Carolina. 1978.
3-3. Copper in 1977, Mineral Industry Surveys. U.S. Department
of the Interior, Bureau of Mines, Washington, D.C. March
1978.
3-4. Arthur D. Little, Inc., Cambridge, Massachusetts. Economic
Impact of Environmental Regulations on the United States
Copper Industry. EPA Contract No. 68-01-2842. U.S.
Environmental Protection Agency, Washington, D.C.,
American Mining Congress. January 1978.
3-5. Battelle Columbus Laboratories, Columbus, Ohio.
Nonferrous Metals Technical Awareness Bulletin. U.S.
Environmental Protection Agency, Industrial Research
Laboratory, Cincinnati, Ohio. Volume 1, Issue 7,
May/June 1978.
3-6. Benneh, Harold J. An Economic Appraisal of the Supply of
Copper from Primary Domestic Sources. Information
Circular - 5898. U.S. Department of the Interior,
Bureau of Mines, Washington, D.C. 1973
3-7. Battelle Columbus Laboratories, Columbus, Ohio. Energy
Use Patterns in Metallurgical and Nonmetallic Mineral
Processing (Phase 4 - Energy Data Flowsheets,
High-Priority Commodities). U.S. Department of the
Interior, Bureau of Mines. Open File Report 80-75.
1975. 192 pp.
3-8. Institute of Gas Technology. Study of Industrial Uses of
Energy Relative to Environmental Effects. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. July 1974.
3-109
-------
3-9. Outlook for Copper Industry - Not Bright. Chemical
Engineering Progress 74(9):84-87. September 1978.
3-10. Impact of Environmental Control Expenditures on Copper,
Lead and Zinc Producers. American Mining Congress
Journal, 64(l):45-50. January 1978.
3-11. Demand Dissolves the Copper and Nickel Glut. Business
Week. February 2, 1979. pp. 112B,D,F.
3-12. Charles River Associates, Inc. Boston, Massachusetts.
Lead, Copper, Zinc Price Forecasts to 1985. Volume I.
CRA #410. U.S. Environmental Protection Agency,
Washington, D.C. August 1978.
3-13. Lancer, H. Copper. In: Kirk Othmer Encyclopedia of
Chemical Technology. 2nd ed. V.6. New York,
Interscience Publishers. 1967. p. 131-181.
3-14. Hallowell, J.B., J.F. Shea, G.R. Smithson, Jr., A.B.
Tripler, and B.W. Gonser. Water Pollution Control in
the Primary Nonferrous-Metals Industry — Volume I
Copper, Zinc, and Lead Industries. EPA-R2-73-247a.
Washington, U.S. Government Printing Office. 1973.
168 p.
3-15. Environmental Assessment of the Domestic Primary Copper,
Lead and Zinc Industries. V.I. EPA Contract No.
68-02-1321, Task No. 38. Cincinnati, PEDCo Environmental,
Inc. November 1976. 398 p.
3-16. Treilhard, D.G. Copper - State of the Art. Engineering
and Mining Journal 174(4): April 1973. p. p-2.
3-17. U.S. Environmental Protection Agency. Assessment of
Industrial Hazardous Waste Practices in the Metal
Smelting and Refining Industry. V.2, Primary and
Secondary Nonferrous Smelting and Refining. SW-145c.2.
Springfield, VA, National Technical Information Service.
1977. 244 p.
3-18. Background Information for New Source Performance
Standards: Primary Copper, Zinc, and Lead Smelters,
Volume 1 — Proposed Standards. EPA-450/2-74-002a.
Springfield, VA, National Technical Information
Service, October 1974. 756 p.
3-110
-------
3-19. Development Document for Interim Final Effluent Limitations
Guidelines and Proposed New Source Performance Standards
for the Primary Copper Smelting Subcategory of the Copper
Segment of the Nonferrous Metals Manufacturing Point
Source Category. EPA 440/1-75/032-b, Group I, Phase II,
Effluent Guidelines Division, Office of Water and
Hazardous Materials, U.S. EPA, Washington, D.C. November
1974, 213 p.
3-20. Personnel Communication Between Calspan Corporation,
Buffalo, New York, and Phelps-Dodge Corporation.
November 1974.
3-21. U.S. Environmental Protection Agency. Assessment of
Industrial Hazardous Waste Practices in the Metal
Smelting and Refining Industry. V.4. Appendices.
SW-145c.4. Springfield, VA, National Technical
Information Service. 1977. 62p.
3-22. Personal Communication Between Calspan Corporation,
Buffalo, New York, and Cities Service Corporation,
Copperhill, Tennessee. November 1974.
3-23. Personal Communication Between Kennecott Copper Corporation
and PEDCo Environmental, Inc. January 1979.
3-24. Personal Communication Between Phelps-Dodge Corporation and
PEDCo Environmental. January 1979.
3-25. SCS Engineers. Comprehensive Sludge Study Relevant to
Section 8002(g) of the Resource Conservation and Recovery
Act of 1976 (PL 94-580). EPA Contract No. 68-01-3945.
No Date.
3-26. Federal Register, Vol. 43, No. 243, Monday, December 18,
1978.
3-27. Midwest Research Institute, A Study of Waste Generation,
Treatment, and Disposal in the Metals Mining Industry.
National Technical Information Service. PB-261 052.
October 1976.
3-28. Draft Environmental Impact Statement, Proposed Regulation,
Criteria for Classification of Solid Waste Disposal
Facilities. U.S. Environmental Protection Agency,
Office of Solid Waste. April 1978.
3-29. MacDonald, .B.I., and M. Weiss. Impact of Environmental
Control Expenditures on Copper, Lead, and Zinc Producers.
Mining Congress Journal, January 1978.
3-111
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SECTION 4
PRIMARY LEAD SMELTING AND REFINING INDUSTRY
Industry Characterization
The U.S. primary lead industry is faced with a number of
problems, serious enough that they could lead to suspension of
operations at marginal smelters. Environmental regulations and
associated compliance costs, transportation costs, depressed
domestic markets, labor strikes, oversupply at primary smelters,
refineries, and consumer plants head the list of problems.
Despite this situation, the United States ranks above all other
countries in consumption and production of lead. It is estimated
that domestic reserves will meet the forecast demand to the year
2000; however, in order to economically extract these ores, the
domestic industry would have to raise the price of lead.
Therefore the United States heavily relies on imported materials
and is expected to continue this reliance.
The domestic primary lead industry consists of mining,
concentrating, smelting, and refining segments. Except in small
operations, the ore is generally concentrated at the mine and
then shipped to the smelter. Of the six smelters that process
lead concentrates, four have refineries on site. The other two
ship their lead bullion to a centrally located refinery. Lead is
4-1
-------
produced from concentrates by pyrometallurgical processes:
sintering to remove sulfur and convert galena (PbS) to lead oxide
(PbO); reduction to produce lead bullion; and refining to remove
impurities. Several refining operations also selectively recover
valuable metals associated with the lead. Research is in
progress to develop hydrometallurgical techniques for recovering
lead from sulfide ores. These processes are being designed to
treat lead ores economically and reduce the amount of polluting
wastes emitted during lead production.
Industry Description
Raw Materials—Concentrates produced by the beneficiation of
various lead-containing ores are the main input material for
production of refined lead. Two different types of concentrates
are used in production of primary lead. Most abundant are those
from Missouri, consisting of almost pure galena, with only small
quantities of other metals. The other type, constituting almost
20 percent of domestic concentrates, is usually mined,
concentrated, and smelted in western states; these concentrates
are extracted from complex ores containing minerals of other
metals, chiefly zinc, silver, and copper. The different types of
concentrates and recycled materials (slags and residues) are
usually stored in separate bins at the lead smelters and are
combined to form specific blends before being fed to the process.
The ores from which concentrates are recovered also vary.
Of an estimated 592,000 tons (537.0 Gg) of lead mined
domestically in 1977, 82 percent was produced from lead ores and
4-2
-------
18 percent from all other ores (4-1). Missouri, Idaho, Colorado,
and Utah were the four leading states in mine production. In
addition to domestic ores, approximately 73,340 tons (66.53 Gg)
of lead in the form of ores and concentrates was imported and
processed at U.S. smelters.
Lead deposits normally are composed of galena, a lead
sulfide mineral that often occurs in association with pyrite,
sphalerite, chalcopyrite, and pyrrhotite. Generally galena is
resistant to weathering, but oxidation products such as anglesite
(PbSC>4) and cerussite (PbCOg) are commonly found in outcrops.
In the pure state, lead content can reach 86.6 percent of
the ore. Presently mines are economically extracting lead from
ores with lead content ranging from 2 to 50 percent.
Sphalerite, pyrite, chalcopyrite, and other sulfides also
are commonly associated with western ores. Although the Missouri
ores contain almost exclusively galena, mineral traces of other
metals are common.
Several other raw materials are used in production of
primary lead. Agents are often added to promote or enhance
various reactions occurring in the process. For example, iron,
silica, and limestone flux are added to the sinter feed to ensure
proper sinter characteristics. In addition, coke, soda ash,
pyrite, zinc, and caustic are added at various points in the
smelting and refining process. Other materials sometimes added
to the process for recovery of lead values include, for example,
particulates and sludges collected in pollution control devices
4-3
-------
and cleanup materials. These residues are generally recycled
within a plant, but are sometimes transferred to an offsite
facility for processing.
Production and Capacity—Refined lead is the principal
product of lead smelting and refining. The major end uses of
lead include lead storage batteries, gasoline additives,
construction materials, cable coverings, and sporting ammunition.
Important byproducts of primary lead include copper, gold,
silver, and zinc. Minor byproducts include sulfuric acid,
cadmium, antimony, bismuth, and tellurium. Because the cadmium
market is currently depressed, the amount of cadmium recovered
from smelter dusts and slags is very small and continues to
decrease. Lead smelters also produce sulfuric acid from
off-gases containing sulfur dioxide; this is done chiefly as a
pollution control measure. Generally the acid is sold at a loss.
Occasionally, a small amount is used for leaching within the
plant or at nearby mine sites.
Lead production from primary refineries in 1977 was 611,650
tons (554.8 Gg), which represents utilization of 77.9 percent of
total plant capacity (4-1). The value of this production was
$370 million, based on the 1977 average U.S. producer price of
primary metal.
The Bureau of Mines estimates that primary lead production
will be 780,000 tons (707.5 Gg) in 1985 and 990,000 tons (898.0
Gg) in 2000 (4-2). Based on these estimates, the annual growth
rate for primary lead production is 3.086 percent for the period
4-4
-------
1977 and 1985, and 1.602 percent for the period 1985 to 2000.
Based on these factors production estimates have been developed
for the years 1980, 1990, and 1995 (Table 4-1).
Between 1972 and 1978 the price of lead increased steadily
but slowly, except in 1975 when the economy entered a recession.
The average U.S. producer price in 1977 was $0.3070 per pound.
The price rose slightly in the first half of 1978 to $0.3260 per
pound. The 1977 domestic delivered prices of copper, silver, and
gold as a comparison were $0.6696 per pound, $4.62 per troy
ounce, and $148.31 per troy ounce, respectively.
Between 1961 and 1971 lead smelters were closed because of
the opening of the "New Lead Belt" in Missouri. Subsequently two
new smelters were opened in Missouri, and St. Joe's Herculaneum
smelter was rebuilt. Although the number of smelters declined
during this period, primary production increased. The capital
costs (including operating costs) of a 100,000 ton-per-year
smelter in 1976 were calculated at $580 per ton of annual
capacity (4-2).
Companies—The primary lead industry comprises four
companies that operate four integrated lead smelters refineries,
two lead smelters, and one lead refinery (Table 4-2). All of the
smelter production is located in Missouri, Montana, Texas, and
Idaho. In 1977 approximately 4,700 persons were employed at
domestic mines and mills including lead, lead-silver, and
lead-zinc mines and mills. Primary lead smelters and refineries
employed 2,400 persons (4-2). Many of the companies producing
4-5
-------
TABLE 4-1
U.S. PRIMARY LEAD INDUSTRY STATISTICS*
(tons, except as noted)
Production
Refinery
Refined lead
Antimonial lead
All primary lead
Mine
Recoverable
1980
1985"1"
1990
1995
2000^
Imports
Ores and concentrates
Lead content
Refined metal
Exports
Lead material excluding scrap 9,845
Consumption
Reported 1,298,805
Average U.S. producer price, common lead ($/lb) 0.3070
January-May 1978 0.3260
Total value of annual refinery production (millions $) 37 0
* Refined metal mineral industry surveys. Lead industry in
May 1978. U.S. Department of the Interior, Bureau of Mines,
Washington, D.C. August 23, 1978. All values are 1977
statistics unless otherwise noted.
* Ryan, J.P. and J.M. Hague. Lead-1977. Mineral commodity
profile - 9. U.S. Department of the Interior, Bureau of Mines,
Washington, D.C. December 1977.
Note: Metric conversion table is given in front matter.
604,933
6, 657
611,650
592,491
657,000
780,000
844,500
914,000
990,000
73,340
269,341
4-6
-------
TABLE 4-2
U.S. PRIMARY LEAD PRODUCERS*
Capacity First year
Company and location Description (tons/year) of operation'1' Products
Amax-Homestake Lead Tollers
Boss, Mo.
Smelter/refinery
140,000
1968
Refined lead, copper
dross, lead/silver
dross, sulfuric acid
Asarco, Inc.
East Helena, Mont.
Smelter
120,000
1888
Drossed lead, zinc oxide,
copper matte, sufuric
acid
El Paso, Tex.
Smelter
120,000
1887
Drossed lead, zinc
oxide, copper matte,
sulfuric acid, cadmiums
Glover, Mo.
Smelter/refinery
110,000
1968
Refined lead, copper
dross, lead/silver
dross
Omaha, Nebr.
Refinery
180,000
1870
Refined lead,
sulfuric acid
Bunker Hill Company
Kellogg, Idaho
Smelter/refinery
130,000
1917
Refined lead, cadmium
sponge, lead-zinc
oxide, copper matte,
sulfuric acid
St. Joe Minerals Corporation
Herculaneum, Mo.
Smelter/refinery
225,000
1891
Refined lead, silver
granules, sulfuric
acid, copper matte
* Wison, B.G., et al. An interdisciplinary investigation of environmental pollution by lead and other
heavy metals from industrial development in the new lead belt of southern Missouri. University of Missouri,
Rolla and Columbia, Missouri, June 1974.
* U.S. Environmental Protection Agency. Draft effluent guidelines, primary lead smelting and refining.
June 1974. These are original dates but most of these facilities except for Boss and Glover, Missouri have
been extensively rebuilt.
Note: Metric conversion table is given in front matter.
-------
primary lead are vertically integrated and therefore are involved
in two or more process segments. Often these firms own interest
in processing other valuable metals, such as copper, zinc,
silver, and gold. Recovery of these metals sometimes makes the
mining and processing of the lead ores economical.
Energy Consumption—In 1973 the domestic primary lead
industry consumed approximately 23.9 trillion Btu (25 PJ) of
energy. The average unit consumption rate, including all
processes in the mining, concentrating, smelting, and refining
segments, was 27 million Btu/net ton (31 GJ/Mg) of refined lead
(4-3). Of the total, smelting consumed 20.81 million Btu/net ton
(24 GJ/Mg) of decopperized bullion and refining consumed 4.79
million Btu/net ton (5.5 GJ/Mg) of refined lead.
Total energy consumption is expected to increase 24 percent
between 1972 and 1985 (4-4). This increase in energy consumption
could be reduced if the domestic industry were to adopt such
processes as direct smelting, flash smelting, the Boliden
process, and hydrometallurgical techniques (4-4).
Hydrometallurgical techniques appear to be the most promising
because they could reduce both energy consumption and generation
of polluting wastes.
Outlook--The viability of the lead industry will depend
directly on adaptation to environmental regulations, which will
have direct impacts on future demand, consumption, and production
of primary lead. The degree to which these regulations are
4-8
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applied to the lead industry will dictate the severity of the
impacts.
Forecasts indicate that the domestic demand for primary lead
in 2000 will fall between 1,030,000 tons (908.2 Gg) and 2,340,000
tons (2.1 Tg) (4-2). The Bureau of Mines estimates that between
1976 and 2000, the average growth rate in the United States will
be 1.9 percent.
Demand can be divided into four main categories: metal
products, chemicals, pigments, and miscellaneous. Lead acid
batteries are a major end use of metal products. In an effort to
improve mileage ratings, the automobile industry is examining
lead-cadmium batteries that use 10 to 15 percent less lead and
weigh less than the current lead acid batteries.
The major end use in the chemical category is tetraethyl
lead as a gasoline additive. Full implementation of the
phasedown schedule for reducing the lead content of gasoline, in
keeping with EPA regulations, could cut demand for lead additives
91 percent by 2000 (4-2). Also the demand for lead pigments is
decreasing because of their toxicity. If the automobile industry
opts for production of electric-powered vehicles, the demand for
lead in the form of lead acid batteries could easily make up for
all other decreases in demand.
The Bureau of Mines projects that world smelter capacity
will increase to 5,335,000 tons (64.8 Tg) in 1980, with domestic
smelter capacity remaining constant. Industry analysts indicate,
however, that full implementation of the 1.5 microgram per cubic
4-9
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meter standard for lead in ambient air may force some primary
smelters to close (4-5) and thus reduce future domestic capacity.
The future of the lead industry relies heavily on lead acid
batteries. The singularity of the market line makes the industry
vulnerable to changes. Historically, the price of lead has
remained relatively constant. In the next 3 to 5 years prices
should continue constant, ranging only $0.02 to $0.04 per pound
above the present price of $0.3260 per pound (4-6).
A recent study conducted by Charles River Associates
generated forecasts of copper, lead, and zinc prices through 1985
(4-7). Two scenarios (one for moderate growth and one for rapid
growth) were based on variations of the following factors:
regulatory restraints, depressed prices of coproducts and
byproducts, lack of smelter and refinery expansion, and
increasing imports. The moderate-growth scenario forecasts a
slight decline in the price path of real (deflated) U.S. lead
prices; the rapid-growth scenario predicts a modest increase of
lead prices. The modest-growth scenario estimates that lead
prices will decrease from $0,327 per pound in 1977 to $0,307
(constant 1978 dollars) per pound in 1985. The rapid growth
scenario projects that lead prices will increase from $0,327 per
pound in 1977 to $0,381 per pound in 1985. In current dollars,
the 1985 price of lead is predicted to be $0,448 per pound with
moderate growth and $0,555 per pound with rapid growth.
The "New Lead Belt" of southeastern Missouri was discovered
in 1965. Mining of this deposit began in 1967, and it now
4-10
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produces more than 80 percent of the ore that is mined in this
country specifically for lead (4-8). Two new smelters were added
in 1968 to process the increased Missouri mine production. Since
then, however, very little expansion has taken place. A
depressed market and environmental protection costs have
discouraged new plant expansions and have led to suspension of
operations at several mines, smelters, and refineries. The
Bunker Hill Company, for example, recently announced the
suspension of their zinc fuming plant at the Kellogg smelter
refinery (4-9).
As mentioned earlier, commercialization of the electric car
could radically expand the present market for lead acid
batteries. Progress has been made in developing lightweight lead
acid batteries, but improvements must be made in their
power-to-weight ratios (4-2).
The Bureau of Mines is conducting research on
electrochemical methods of refining lead sulfides. Two of these
hydrometallurgical processes include a ferric chloride (FeCl3)
leach and a chlorine-oxygen leach. The ferric chloride leach
extracts lead from galena to yield lead chloride and elemental
sulfur (4-10, 4-11). The chlorine-oxygen leach is a two-stage
process for extraction of metal values from complex sulfide
concentrates (4-12). Both of these methods produce lead without
the pollution that is associated with smelting.
4-11
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Process Description
All domestic smelters and refineries produce lead by
pyrometallurgical smelting and refining processes. Three
integrated smelter-refineries are located in Missouri and
primarily treat Missouri ore concentrates. One integrated
smelter-refinery and two smelters treat lead concentrates from a
variety of sources, both foreign and domestic. The two
non-integrated smelters ship unrefined lead to a common refinery.
The major process steps are the same at all the smelters and
refineries but those that treat non-Missouri ore concentrates use
auxiliary operations to recover valuable metals or remove
undesirable impurities. Figure 4-1 is a process flow sheet
representing the pyrometallurgical smelting and refining of lead.
Smelting—Smelting is the first step in converting lead ore
concentrate into a salable lead product. It converts the lead
concentrate to an impure lead bullion suitable for refining. The
processes in smelting are sintering, reduction, slag fuming,
drossing, and decopperizing.
Initial treatment of lead concentrates is a sintering
operation to agglomerate the fine particles, convert metallic
sulfides to oxides, drive off volatile metals, and eliminate most
of the sulfur as sulfur dioxide (Process No. 1). Sintering is
done on a traveling-grate furnace called a "sinter machine." The
concentrates is fed onto the moving grate to pass under a burner
that ignites it. The burning concentrate then moves into the
main part of the sinter machine, where air is forced through the
4-12
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I
OJ
$ LIQUID WASTE
9 ATMOSPHERIC EMISSION
SOLID HASTE
Figure 4-1. Flow chart depicts primary lead smelting
and refining (numbers correspond to process numbers in text).
-------
bed of concentrate and combustion is completed. The air is
forced down through the bed (downdraft) or up through the bed
(updraft). The updraft machine is preferred because any metallic
lead produced during sintering solidifies and remains in the bed.
Although downdraft machines are still in use, new -installations
and replacements are the updraft type. Ore concentrates for
sintering are mixed with fluxes, recycled sinter, and flue dusts;
moisture is added, and the mixture is pelletized, then fed to the
sinter machine to form a layer 4 to 5 inches (10 to 13 cm) thick
on the grate (4-8). The mixture is fired and fuses into a firm,
porous sinter. As the sinter leaves the sinter machine it is
sized for use in the blast furnace. Fine sinter particles are
recycled to charge mixing.
Sintering produces no direct solid waste, since all solids
are either recycled or sent to the next operation. Particulates
emitted during sintering are collected and recycled. Four lead
plants use baghouses and the other two use electrostatic
precipitators to control particulates (4-8). Off-gases from
sintering may contain sulfur dioxide in concentrations that are
practical for sulfur recovery by conventional means. Four plants
have sinter machines designed to produce an off-gas containing
enough sulfur dioxide for recovery of sulfur as sulfuric acid.
Operation of the sulfuric acid plant generates a stream of weak
acid called acid plant "blowdown", which cannot be sold.
Neutralization of the blowdown before release could generate a
4-14
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solid waste. This solid waste results indirectly from sintering
and occurs only at facilities producing sulfuric acid from the
sinter machine off-gas.
Sinter is charged to the blast furnace and smelted to a
crude lead bullion that can be further refined (Process No. 2).
The blast furnace is a vertical water-jacketed column supported
on a refractory base. Sinter, coke, limestone, and other fluxing
materials are charged through a water-jacketed shaft at the top
of the furnace. The feed settles to the bottom of the furnace,
where air is injected through side-mounted tuyeres to allow
complete formation of metal oxides and raise the temperature of
the charge. Because not enough air is added for complete
combustion, the coke in the charge forms carbon monoxide, which
reduces the oxides in the charge to metal in the following
principal reactions (4-13):
PbO + CO -> Pb + C02
c + o2 - co2
C + C02 -» 2C0
During reduction the components of the feed melt and separate
into as many as four distinct liquid layers, depending on the
composition of the sinter. The bottom layer is lead bullion, 94
to 98 weight percent lead, containing copper, tin, arsenic,
antimony, silver, and gold. If the sinter is high in arsenic
and/or antimony, a speiss layer consisting of arsenides and
antimonides of iron and other metals forms on top of the lead.
Copper in the ore reacts with residual sulfur to form a matte
4-15
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layer on top of the speiss. Slag resulting from the interaction
of fluxes and metal impurities forms the top layer in the blast
furnace (4-8). The liquid layers formed during blast furnace
operation are tapped for removal. Crude lead bullion is charged
to the next operation, drossing. Matte and speiss are sold to
copper smelters for metal recovery. Slag disposal depends upon
the zinc content of the slag. A slag containing economically
recoverable amounts of zinc is sent to a zinc fuming furnace,
whereas a slag containing less zinc is discarded.
Blast furnace slag or zinc fuming slag is the major solid
waste from lead smelting and refining. Slag disposal practices
are similar, whether or not zinc fuming is practiced. The slag
is either hot-dumped on the slag pile or granulated in a water
jet and transported to the slag pile. Three of four plants
granulate the slag and dewater it before disposal. Granulating
water is then cleaned in thickeners to remove entrained slag,
cooled, and returned to the granulation circuit (4-14).
Particulates emitted in the off-gas stream during blast furnace
operation are collected in a baghouse or electrostatic
precipitator and recycled. The off-gas stream from the blast
furnace also contains small quantities of sulfur dioxide. Where
the sulfur dioxide concentration is not high enough for
conventional sulfur recovery, chemical scrubbing may be needed
for sulfur dioxide control; depending on the method, scrubbing
could create a solid waste that must be disposed of.
4-16
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The zinc fuming process recovers zinc and lead from the
blast furnace slag by heating it to 1000 to 1200°C in a furnace
(Process No. 3). Coal and air are injected through tuyeres at
the bottom of the furnace. Air is admitted in the amount needed
to produce a reducing atmosphere of carbon monoxide inside the
furnace. Zinc oxide and lead oxide are reduced, volatilized, and
carried out of the slag in the off-gas stream. Zinc and lead
vapor in the off-gas is then oxidized by adding air at the top of
the furnace. The particulate oxides are recovered from the gases
in a baghouse. Zinc is then usually recovered from the baghouse
dusts by treatment at an electrolytic zinc refinery. All
particulates from zinc fuming are recycled for zinc recovery, and
the slag is treated as described earlier.
The blast furnace bullion undergoes "drossing" to remove
common metallic impurities (Process No. 4). Although drossing is
the initial refining operation, it is usually done at the smelter
before the lead bullion is transferred to the refinery. Blast
furnace bullion is charged to a drossing kettle, agitated, and
cooled to just above its freezing point. At this temperature the
oxides of lead, copper, and other impurities soluble at higher
temperatures solidify and float to the surface, forming a dross.
Dross that is skimmed during this operation constitutes 10 to 35
percent of the blast furnace bullion (4-13). Dross is composed
of 90 percent lead oxide, 2 percent copper, 2 percent antimony,
and lesser amounts of other elements. After removal from the
kettle, it is sent to the dross reverberatory furnace for further
4-17
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processing. Off-gases from the drossing kettle contain small
quantities of particulates, fume, and sulfur dioxide. They are
combined with the blast furnace off-gases for control of
particulates, and the captured particles are recycled.
Dross separated from the lead bullion must be further
treated in a reverberatory drossing furnace to recover metal
values (Process No. 5). Dross is charged into the reverberatory
furnace with pig iron, silica sand, and limerock (optional)
(4-8). The charge is smelted, and the products separate into
four layers: slag on top, matte and speiss intermediate, and
molten lead at the bottom. Slag, amounting to 2 to 4 percent of
the charge, and lead, equaling about 50 percent of the charge,
are returned to the blast furnace (4-8). Matte and speiss are
tapped separately, granulated, and shipped to copper smelters for
recovery of copper and precious metals. Because all solids are
recycled, the process yields no solid wastes. Off-gases from the
reverberatory furnace are combined with the blast furnace
off-gases and treated in the same manner.
Rough-drossed lead bullion, still containing copper, is
decopperized before further refining (Process No. 6).
Decopperizing is usually done in the same kettle as rough
drossing; at some plants it is done in a different kettle, or if
the refinery is near the smelter the bullion may be transferred
there for decopperizing.
The rough-drossed bullion is agitated while sulfur is added
to the kettle. The sulfur combines with the remaining copper,
4-18
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forming cuprous sulfide (Cu2S), which floats and is skimmed off
the lead bullion. The dross removed during decopperizing is
either charged to dross reverb or, in two-stage drossing,
returned to the first drossing kettles. Decopperizing produces
no solid wastes because all collected solids are recycled for
metal recovery.
Refining—Rough-drossed lead bullion must be further refined
to remove metals that cause the lead to be hard or that are
valuable in themselves. These additional metals must be removed
before the lead can be sold commercially. Separation is done in
stages to facilitate recovery of the valuable metals: softening,
desilverizing, dezincing, debismithing, final refining, and
casting. The softening process removes the elements that make
lead hard and interfere with further refining (Process No. 7).
Softening is done by oxidizing the contained metals such as
antimony, arsenic, tin, and copper, to cause formation of
metallic oxides, which float to the surface of the molten lead
and are skimmed off.
Softening is done by three processes: reverberatory
softening, kettle softening, and Harris softening. In
reverberatory softening the metals are oxidized with air. Lead
is pumped into one end of a reverberatory furnace and air is
blown through the molten metal. The metal oxides rise to the
surface of the bath, forming a slag that is skimmed off and
treated for metal recovery. When hardness of the lead is greater
4-19
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than 0.3 to 0.5 weight percent antimony equivalent, litharge
(PbO) is added to increase the rate of oxidation (4-13).
Kettle softening can be used only on bullions of 0.3 percent
hardness or less (4-13). The metals are oxidized with caustic
soda (NaOH) and sodium nitrate (NaNOg, niter). The bullion is
melted and is agitated as the fluxes are added. The fluxes react
with the impurities to form salts such as sodium antimonate
(NaSbOg) (4-13). When the oxidation reactions are completed, the
agitation is stopped and the slag is skimmed off.
Harris softening is done with the same reagents used in
kettle softening and under the same conditions of low impurities.
It consists of two steps: the first is a pyrometallurgical
process, identical to kettle softening; the second step is a
hydrometallurgical process for recovery of antimony. The slag is
crushed and leached with hot water to dissolve the sodium salts.
The solution is then cooled to preferentially precipitate sodium
antimonate. The sodium antimonate is filtered from solution and
processed to recover antimony. The filtrate is further processed
to precipitate the calcium salts of arsenic and tin, which are
recovered separately and sold.
Solid wastes from these processes are slags produced by
softening. Slags from kettle softening and the leached slag from
Harris softening are discarded with slags from the blast furnace
or zinc fuming furnace. Slag from reverberatory softening and
the sodium antimonate recovered during Harris softening are
treated to recover the metal values. The desired product
4-20
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determines the type of recovery process. For recovery of
antimonial lead the slag is heated in a furnace with a reducing
agent and slagging fluxes so that lead and antimony are
preferentially reduced. Slag is formed and skimmed off, and the
antimonial lead is recovered as a marketable product. The slag
is recycled for metal recovery. In recovery of antimonial
trioxide (Sfc>2C>3) the slag is treated in a volatilization process.
Slag is heated to volatilize arsenic trioxide and antimonial
trioxide. The two oxides are then separated by selective
condensation. Recovered antimony trioxide is sent to antimony
plants, and recovered arsenic trioxide is sold to arsenic
producers. The residue in the furnace is rich in lead and is
recycled to the blast furnace. The only solid waste from
antimony recovery is the collected arsenic trioxide, a waste
material when it cannot be sold.
Softened lead bullion contains precious metals, gold and
silver, which are recovered for their economic value by the
Parkes desilverizing process before casting (Process No. 8).
Because gold and silver do not oxidize easily they are not
removed in the earlier softening operations (4-8). The removal
of these metals is based on the fact that thorough mixing of
excess zinc (1 to 2 percent) into a molten bath of lead causes
formation of alloys of zinc with gold, silver, and copper.
Because these are insoluble in molten lead saturated with zinc
they rise to the surface (4-13). Degolding and desilverizing are
usually done in two steps. First a small amount of zinc is added
4-21
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in a degolding kettle to recover a skim of high gold content,
which forms because zinc alloys preferentially with gold and
copper. Then zinc is added to recover the silver as a
zinc-silver skim. Because metallic impurities, especially
arsenic, can interfere with desilverizing, they must be removed
prior to desilverizing. Desilverized lead is pumped to the next
step in lead refining. Parker desilverizing yields no solid
wastes because all materials contain valuable metals. Crusts
from desilvering are treated in retorts to recover zinc for
recycling to the desilverizing process. The zinc is volatilized
and condensed in a furnace. The gold-silver alloy remaining
after zinc has been removed is purified to remove metals by a
process called cupelling. In a cupel furnace air is blown into
the molten metal and slagged to remove impurities. Slags
produced during cupelling are recycled to the blast furnace for
metal recovery.
Desilverized lead bullion requires dezincing to remove the
excess zinc added during desilverizing (Process No. 9). Three
processes are used to remove zinc from the lead bullion: vacuum
dezincing, chlorine dezincing, and Harris dezincing. Vacuum
dezincing is used most commonly because the recovered zinc can be
recycled directly to desilverizing. The process is done in a
large kettle so that a vacuum can be drawn on the metal surface
by submerging the skirt of an inverted bell into the metal. Zinc
is vaporized and condenses on the inner dome of the bell, which
is cooled by a water jacket. After the zinc has been removed
4-22
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from the bullion the vacuum is broken and the inverted bell
removed. Solid zinc is peeled from the dome and recycled to
desilverizing.
Chlorine dezincing is based on the greater reactivity of
chlorine with zinc than with lead. Desilvered lead containing
zinc is circulated to a reaction chamber where chlorine is added.
Zinc chloride, formed preferentially, collects on the surface of
the molten lead and is skimmed off. Further treatment of the
zinc chloride skim produces a marketable zinc chloride product.
Harris dezincing is done with the same equipment used in
Harris softening. Caustic soda saturated with lead oxide in a
reaction chamber is used to oxidize zinc to zinc oxide while
reducing the lead oxide to lead. Spent caustic from the reaction
chamber is mixed with fresh caustic and then dumped into a
granulation tank. More fresh caustic is added to the reaction
chamber and the chamber put back into operation. Spent
granulated caustic is processed to recover zinc, antimony, and
caustic.
Because all materials are recovered for reuse or sale, none
of the three processes produces a solid waste.
Desilvered and dezinced lead bullion containing more than
the 0.15 percent specification for bismuth content needs
additional debismuthing prior to casting (Process No. 10).
Bismuth is removed from the lead bullion by the Betterton-Knoll
process. Calcium and magnesium are added to the molten lead to
form ternary compounds (e.g., Caff^B^) with bismuth (4-15). The
4-23
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lead is then cooled, causing the compounds to solidify and rise
to the surface as a dross, which is skimmed off the lead metal.
The purified lead is pumped to casting and the skimmed dross is
treated to recover bismuth. Debismuthing is done only to meet
the bismuth specification for refined lead.
Bismuth is recovered from debismuthing slag in a furnace by
injecting chlorine gas. Magnesium, calcium, and entrained lead
react to form chlorides, which are skimmed from the bath as a
slag. Air is then injected to oxidize any remaining impurities.
Slag is removed, and bismuth, 99.9 percent pure, is cast into
marketable shapes. Slag produced during bismuth recovery is
discarded with slag from the blast furnace.
Lead bullion from dezincing or debismuthing is combined with
flux to remove remaining impurities before casting (Process No.
11). This final fluxing is done to remove calcium and magnesium
residues and lead oxide. Caustic soda and niter are added to the
metal, and the metal is cooled. The remaining impurities rise to
the surface and are skimmed off. Slag produced during the
process is returned to the blast furnace. This process generates
no solid wastes.
Refined lead bullion is cast into ingots for sale (Process
No. 12). Molten lead is transferred to a casting kettle and cast
into lead links, pigs, 1,000-lb (450-kg) ingots, and 2,000-lb
(910-kg) ingots on mechanized casting machines. Casting produces
no solid wastes.
4-24
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Solid Waste Characterization
Sources and Quantities of Solid Waste
This section deals with sources and quantities of solid
wastes generated by the primary lead industry. Model plants are
developed to estimate "average" values for the industry. The
solid waste generation factors, in tons of waste per ton of
product, are calculated on the model basis and then are used to
estimate quantities of solid waste at specific plants where
actual information is lacking or inadequate. The quantities
shown for the model plants are based on average or typical values
from site-specific information in PEDCo files; much of this
information was obtained on site visits, and some through
industry contacts.
Two model plants were developed for the primary lead
industry. Model 1 represents the three integrated
smelters/refineries that process lead concentrates from
Missouri's "New Lead Belt." Model 2 represents smelters and
refineries that process non-Missouri concentrates. Two smelters,
one integrated smelter/refinery, and one refinery fall into this
classification.
The rationale for development of two models is based on the
inherent differences in the Missouri and non-Missouri
concentrates. Missouri concentrates contain substantially more
lead and fewer impurities than non-Missouri concentrates.
Missouri concentrates also vary little in composition. In
contrast, because the non-Missouri plants process concentrates
4-25
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and other lead-bearing materials from a wide variety of sources,
both the input materials and the resultant solid wastes vary in
composition. This variation leads to differences in the
metallurgical processes at plants represented by the two models.
Regardless of model classification, each primary lead
smelter potentially generates two types of solid waste, blast
furnace slag and impoundment dredgings. All smelters produce
blast furnace slag, but not all facilities include impoundments
to collect solids from miscellaneous slurries (plant washings,
plant runoff, acid plant blowdown, granulation water, etc.).
Quantities of each type of waste are calculated by multiplying
the waste generation factor by plant production. Where
plant-specific information is available, actual values are used
in the calculation and are so indicated in the adjusted totals.
At lead plants collected particulates from air pollution
control devices are typically recycled to the process
continuously. These particulates are high in metal content and
are recycled to recover this fraction. One smelter, in the Model
1 classification, is temporarily stockpiling collected
particulates because they are too wet to be recycled immediately.
This procedure was necessitated by installation of a new
treatment system, and continuous recycling will resume when
engineering changes are made. This material has been included in
the solid waste totals. In addition a non-Missouri smelter
reported some collected flue dusts have not been recycled and are
4-26
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stockpiled onsite. Information on the quantity and composition
of these wastes was unavailable.
Detailed flow diagrams for both model plants indicate the
sources of the solid wastes generated and the quantities of the
wastes. Quantities of some materials other than solid waste are
not indicated on the diagrams because of insufficient data; the
emphasis is on values for solid waste rather than a complete
material balance.
For the purpose of standardization, the model plants are
assumed to operate 350 days per year and 24 hours per day at 78
percent of capacity.*
Model 1; Missouri Smelting and Refining—Annual production
of this model plant (Figure 4-2) is assumed to be 123,000 tons
(111.6 Gg) of refined lead per year. The combined production of
the three actual plants represented by this model is 370,000 tons
(335.6 Gg) of refined lead per year. Missouri smelters
constitute 60 percent of the total industry production. Because
of the similarity of concentrates, process flows in the Missouri
lead plants are virtually identical. The main variations are in
production rate and water treatment practices.
The sources of solid waste generated at plants represented
by this model are blast furnace slagging and periodic dredging of
water impoundments.
* Based on U.S. Bureau of Mines production and capacity
figures.
4-27
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NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT HATTER
COUCCHO PMT|Cm«TCS
j- ircw nm
u l l*#OC» flUi
-J
Figure 4-2. In the primary lead industry Model 1 represents Missouri
smelting and refining.
(contq 1)
-------
Figure 4-2.
r»m\ bic'Cko
O filial HlBMCl
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR.
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES.
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER.
(continued)
-------
The blast furnace is a source of solid waste because it is
here that the nonmetallic materials and nonproduct metals present
in the charge are tied up in a slag with the iron, silica, and
limerock fluxes. This complex silicate slag is tapped
continuously and is granulated by thermal shock induced by a
water stream. At the model plant granulated blast furnace slag
is transported to the slag disposal site at a rate of 47,000 tons
(426 Gg) per year or approximately 0.38 ton per ton of lead
product.* The balance of the slag produced is recycled
continuously to the sinter machine as a sulfur diluent and does
not contribute to the solid waste load.
A series of impoundments or basins used for water storage
and treatment receive the slag granulation water and other
process water such as acid plant blowdown (miscellaneous
slurries). This water contains relatively small amounts of
carryover fine slag and other solids. The settled solids are
removed "as needed", and the material moved in this operation is
not typically quantified. The available information indicates
that the amount of dry solids attributable to miscellaneous
surries is 0.07 ton per ton of lead product.! It is assumed that
the impoundments are dredged of these accumulated solids every
year.
* A typical value based on information gathered during site
visits and contacts with industry representatives.
t Adapted from: Office of Solid Waste. Assessment of
Industrial Hazardous Waste Practices in the Metal Smelting and
Refining Industry. V.3. Environmental Protection Report
SW-145C.1. National Technical Information Service. Springfield,
Virginia. 1977.
4-30
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The calculated quantities of solid waste generated at
Missouri lead smelting and refining plants are based on the total
estimated plant production for all plants represented by the
models and the model plant waste generation factors presented in
Table 4-3. Any available plant-specific information is included
in lieu of estimated values; the resulting 'adjusted' totals are
the most accurate and represent all data available.
Model 2: Non-Missouri Smelting and Refining—Annua1
production of this model plant (Figure 4-3) is assumed to be
117,000 tons (106.1 Gg) per year or approximately 330 tons (299
Mg) per day. The plants represented by this model include two
smelters, each with production of 93,600 tons (84.8 Gg) per year
drossed lead, one refinery with production of 140,000 tons (126.8
Gg) per year refined lead, and one integrated smelter/refinery
with production of 101,000 tons (91.5 Gg) per year refined lead.
These plants represent approximately 40 percent of the domestic
primary refined lead production.
The main source of solid waste generated at a non-Missouri
lead plant is the slag fuming operation. In slag fuming the
blast furnace slag, which contains the nonmetallic fraction and
impurities in the charge, complexed with the silica and limerock
fluxes, is processed to recover most of the zinc. Slag from the
model plant's fuming furnace is transported to the disposal site
at a rate of approximately 1.75 tons per ton of drossed bullion.*
* A typical value based on information gathered during PEDCo
site visits and contacts with industry representatives.
4-31
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TABLE 4-3
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY LEAD PLANTS
REPRESENTED BY MODEL 1
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Slag
0.38
141,000
142,600
Slurries
0. 07*
25,900
46,900
Total
166,900
189,500
* Adapted from Office of Solid Waste. Assessment of industrial hazardous waste
practices in the metal smelting and refining industry. 1977.
Note: Metric conversion table is given in front matter.
-------
- m-i CUW1lP« L_
HtGMOUSl 10 !
C~
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 4-3. In the primary lead industry Model 2 represents
non-Missouri smelting and refining.
(continued)
-------
t-CAUStll
0(61 SWtHl/IRC
IMS B[C*fU0
^BiCj "i IJPQSS^
I BKCHOUSt [ a
OUST fltCTCUD
NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure
4-3.
(continued)
-------
A minor amount of slag is also produced during the refining steps
at a rate of approximately 0.05 ton per ton of refined lead.
All but one of the plants represented by this model generate
no solid waste as a result of their water treatment practices.
One of the smelter facilities represented by this model has no
impoundments and currently no acid plant. An acid plant will be
added soon, along with a water treatment plant that will receive
the blowdown from the acid plant. Solids from the treatment
plant will be recycled to sintering. The other smelter uses a
thickener that receives acid plant blowdown and lime. Solids
from the thickener are filtered and recycled to the blast
furnace.
The refinery represented by Model 2 has no impoundments or
water treatment plant that could generate solids. The integrated
smelter/refinery has two impoundments from which dredged solids
are recycled to the process. Solids from the first impoundment,
which receives the blowdown and lime treatment, are thickened,
filtered, and returned to sinter. The second impoundment, which
receives overflow from the first, is occasionally dredged and te
dredgings used as sinter feed. The quantity of solid material
entering the second impoundment was estimated as 2200 tons (2.0
Gg) per year on the assumption that the impoundment is dredged of
half its capacity per year. This quantity of material from the
integrated smelter/refinery has been included in the solid waste
totals because it is occasionally but not continuously recycled.
4-35
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Quantities of solid waste generated at non-Missouri lead
smelters and refineries are calculated with the total estimated
plant production value for all plants represented by Model 2 and
the model plant waste generation factors presented in Table 4-4.
Inclusion of available site-specific information in lieu of
estimated values results in the adjusted totals.
National Solid Waste Totals
The compilation of estimated and reported solid waste
quantities in this study indicates that the primary lead smelting
and refining industry currently generates some 699,200 tons (634
Gg) of solid waste per year (Table 4-5). Missouri plants account
for 27 percent of the total solid waste generated, although they
represent about 60 percent of the industry's production of
refined lead. The largest portion of solid waste generated by
the primary lead smelting and refining industry is furnace slag.
Slag represents 91 percent of the total solid waste generated by
the industry on a national basis; it represents 75 percent of the
total solid waste from Missouri plants and 97 percent of the
total from non-Missouri plants.
The seven primary lead plants are located in four EPA
regions (Table 4-6). Although Region VIII has but one plant, it
accounts for 27 percent of the total solid waste generated;
Region VII, with four plants, accounts for but 28 percent. The
Region VII plants include a refinery generating a relatively
minor amount of waste, about 1 percent of the national total; the
4-36
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TABLE 4-4
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY LEAD PLANTS
REPRESENTED BY MODEL 2
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Smelter slag
1.75
504,000
495,000
Miscellaneous
slurries
0.02
2,000*
2,200
Refinery slag
0.05
12,000
12,500
Total
1.82
518,200
509,700
* Represents the sole non-Missouri plant, which generates miscellaneous slurries.
Note: Metric conversion table is given in front matter.
-------
TABLE 4-5
1978 NATIONAL SOLID WASTE TOTALS FOR THE PRIMARY LEAD
SMELTING AND REFINING INDUSTRY
(tons/year)
Waste type
Quantity generated at plants represented by:
Model 1
Model 2
Total
Slag
Refinery slag
Miscellaneous
slurries
Total
142,600
46,900
189,500
495,000
12,500
2,200
509,700
637 , 600
12,500
49,100
699,200
Note: Metric conversion table is given in front matter.
4-38
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TABLE 4-6
GEOGRAPHICAL DISTRIBUTION OF SOLID WASTE FROM THE PRIMARY
LEAD SMELTING AND REFINING INDUSTRY
(1978)
EPA Region
State
Number
of plants
Annual solid
waste production
(tons/year)
Annual regional
solid waste production
(tons/year)
VI
Texas
1
140,000
140,000
VII
Missouri
3
189,500
Nebraska
1
7,500
197,000
VIII
Montana
1
192,000
192,000
X
Idaho
_1
170,200
170,200
National
Total
7
699,200
699,200
Note: Metric
conversion table
is given in
front matter.
-------
three Missouri plants, which process high-grade ore, thus
generate much less solid waste per unit of production than do the
non-Missouri plants.
National Solid Waste Projections
Projected solid waste quantities are estimated by applying
current solid waste generation factors to the projected
marketable lead production values for the years 1980, 1985, and
1990 (Table 4-7). These estimates are based on the following
assumptions:
1. Distribution of plants in model types remains constant.
2. Solid waste generation factors remain constant at the
current level.
3. The quantity of solid waste produced as a result of air
and water pollution control will not change
substantially; therefore changes in projected solid
waste totals are essentially dependent on production
changes.
Although these assumptions are needed to make the projections,
their limitations must be noted. The quantity of solid waste
going to land disposal in the future as a result of existing and
pending air and water pollution control regulations will
increase; however it is extremely difficult to make a reasonable
estimate of these quantities because all air and water
regulations have not been promulgated, and the current standards
for air emissions and liquid effluents could be altered.
Additionally, the current compliance schedules could change, and
industry could implement any one of several mitigative approaches
to meet air and water regulations. The effect could have
4-40
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TABLE 4-7
PROJECTED SOLID WASTE FROM THE PRIMARY LEAD SMELTING
AND REFINING INDUSTRY
Waste type
Projected solid
(tons/year)
waste
1980
1985
1990
Slag
696,800
811,200
878,300
Misc. slurries
53,600
62,400
67,600
Total
750,400
873,600
945,900
Note: Metric conversion table is given in front matter.
4-41
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profoundly different impacts on solid waste generation. As an
example of the strong impact that may result from pollution
control regulations, the recently announced national emission
standard of 1.5 micrograms of lead in a cubic meter of air,
measured at the plant perimeter, could lead to the closure of all
but one or two of the seven primary lead plants (4-16).
SCS Engineers recently conducted a study that evaluates the
potential impacts of air and water quality regulations on land
disposal of solid waste (4-17). The study addresses the Clean
Air Act of 1970 and its amendments and the Federal Water
Pollution Control Act of 1972 and its amendments. In an effort
to compensate for the numerous variables that will affect future
waste generation, the researchers developed a minimum and maximum
scenario (Table 4-8). Increases in solid waste generation due to
production increases have not been factored out of these values.
It must be noted also that only a portion of these materials will
be disposed of on land and classed as solid waste; the remainder
will be recycled to recover metal contents.
Qualitative Characteristics of Solid Wastes
The slag produced in a lead smelter blast furnace is formed
by combination of the nonmetallic material and nonproduct metals
present in the charge with the iron, silica, and limerock fluxing
material added to the process. Granulated lead smelter slag, as
produced at Missouri smelters, is a black material with the
consistency of coarse sand. Slag that is dumped molten, as at
two of the non-Missouri smelters, is a black, solid-fused mass.
4-42
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TABLE 4-8
TOTAL ANNUAL SLUDGE FROM LEAD SMELTING AND REFINING ATTRIBUTABLE
TO AIR AND WATER QUALITY REGULATIONS*
(1000 tons/year dry weight)
Historic
Minimum scenario"!"
Maximum scenario^
Legislation
1967
1977
1980
1984
1987
1980
1984
1987
Water pollution
control act
8.01
11.5
14.8
16.4
17.7
14.8
16.4
17.7
Clean air act
53.7
95.3
122.8
136.3
146.3
137. 5
176.9
389.2
Total
61.71
106. 8
137.6
152.7
164.0
152.3
193.3
406.9
* Office of Solid waste. Comprehensive Sludge Study Relevant to Section 8002(g)
of the Resource Conservation and Recovery Act of 1976 (pi 94 580). V. 1.
Environmental Protection Contract No. 68-01-3945. Washington.
^ See Appendix B for explanation of scenarios.
Note: Metric conversion table is given in front matter.
-------
This slag is a complex iron-calcium-aluminum silicate, which
contains minor amounts of nonferrous oxides and sulfides.
Typical slag analyses for Missouri and non-Missouri lead
smelters are presented in Table 4-9.
The miscellaneous slurries generated at lead plants are
difficult to characterize because of the variation in quantity
and composition, which depend on operating conditions and
practices. Thus the wastes vary among plants and also with time
at any one facility. For example, the content of acid plant
blowdown varies with the efficiency of the gas precleaning device
and with the material present in the sinter machine charge.
Operators report that acid plant blowdown contains recoverable
metal to the extent that recycling is desirable. Acid plant
blowdown is acidic and must be neutralized with lime.
Composition of other slurries in this category fluctuates widely.
Plant runoff contains mainly mud and silt, whereas plant washdown
contains a substantial amount of lead and other process
materials. Slag granulation water contains some carryover slag.
Although this material is of the same composition as slag, the
particles are smaller.
The degree of leaching of materials from lead blast furnace
slag is not considered sufficient to identify this waste as
potentially hazardous (4-18). Evidence indicates, however, that
leaching of heavy metals from acid plant blowdown and
miscellaneous slurries is significant enough that these wastes
are considered potentially hazardous (4-18). In concurrence with
4-44
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TABLE 4-9
TYPICAL ANALYSIS OF LEAD BLAST FURNACE SLAG*
(all values are percent by weight except Au and Ag,
which are ounces per ton)
Parameter
Missouri
Non-Missouri
(dezinced)
Pb
2.0-3.8
0.05
Cu
in
CN
•
o
1
1—1
.
o
0.34
Zn
9.0-15.0
1.0
Si02
20.0-24.1
25.6
FeO
24.7-33.0
28.9
CaO
9.0-17.0
19.8
a12°3
3.7-5.0
5.3
S
1.0-2.5
1.1
MnO
1.3
MgO
3.5-5.0
2.0
Au
0.0008
Ag
0.1
0.56
Co
0.3
As
0.09
Ni
0. 04
Cd
0.003
* Data obtain during PEDCo site visist and contacts
with industry representatives.
Note: Metric conversion table is given in front matter.
4-45
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these considerations the Federal Register of December 18, 1978
(43 Fed. Reg. 58946) lists primary lead blast furnace dust,
primary lead lagoon dredging from smelters, and primary lead
sinter dust scrubbing sludge as processes generating hazardous
wastes (4-19). The information gathered during the completion of
this study indicates that virtually all dusts and sludges
collected or generated by air pollution control devices are
continuously recycled. Those sludges and slurries not
continuously recycled (i.e. acid plant blowdown) are treated in
on-site surface impoundments and are periodically dredged.
Throughout this report, therefore, all impoundment dredgings are
considered to be hazardous wastes; blast furnace and zinc fuming
furnace slag are considered nonhazardous wastes.
Solid Waste Control Practices and Costs
This section describes practices for control of solid wastes
(hazardous and nonhazardous) generated by primary lead smelters
and refineries, and their associated costs. The first portion
deals with current control practices used by the lead industry
and the costs attributable to the current practices. Next are
presented alternative control practices, which provide what are
considered to be adequate environmental safeguards and which
satisfy the RCRA Criteria. The costs attributable to this
alternative system are then estimated.
The alternative control systems specified in this study are
based on contractor investigations and on professional judgement;
4-46
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they do not necessarily reflect EPA thinking or policy. The RCRA
Criteria for nonhazardous waste were used as guidelines in
developing the alternative systems, with consideration for both
technical and economic feasibility. The alternatives are not to
be considered as operational guidelines or standards that
industry should be required to follow; rather, they represent the
level of effort that could be required and the magnitude of cost
that could be incurred.
The costs presented for the current and alternative control
systems, are estimates based on a control facility life of 20
years. The costs are those that would be incurred during the
life of the control facility. The cost of closure of existing
facilities for accumulated wastes is also estimated for the lead
smelting and refining industry.
The final portion of this section is an analysis of the
solid waste control costs. The analysis includes calculation of
the incremental cost that would be incurred by the lead smelting
and refining industry through implementation of the alternative
control system and closure of existing waste facilities. The
portions of the incremental cost that are attributable to control
of nonhazardous and of hazardous solid wastes are designated;
then the fraction of the incremental cost for nonhazardous solid
waste control that can be attributed to the RCRA 4004
(nonhazardous waste) Criteria (Criteria-induced cost) is
determined on a state basis. These additional costs attributable
to RCRA for disposal of nonhazardous wastes are compared with
4-47
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other industry costs incurred in complying with current
regulations for air and water pollution control.
Current Solid Waste Control Practices
Current solid waste control practices are fairly uniform
throughout the lead industry. In all but one case, which
involves only 1 percent of the total slag generated, slag is
stockpiled onsite. The sole exception involves slag from a Model
2 refinery, that is removed by a private contractor. Likewise,
all solids contained in the miscellaneous slurries, if not
recycled, are contained onsite in surface impoundments, from
which the solids are periodically dredged and stockpiled onsite
or recycled. Not all plants have such impoundments.
Current control practice typically involves minimal effort
for disposal site selection and preparation. Site selection is
based primarily on convenience. Site preparation consists
primarily of clearing and grubbing the slag disposal area and
scooping out earth to form impoundments. Surface impoundments
generally are located and constructed to provide adequate control
of the plant water and usually result in discharge from a single
point. Current control practice does not involve the use of
sealants or liners beneath disposal areas. Likewise, wells to
monitor seepage or groundwater contamination from disposal sites
are not adequately utilized and usually are not used at all. In
general, systems of drainage collection and diversion ditches
have not been utilized to their fullest potential for control of
surface water.
4-48
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Current Control of Slag—Current practices for slag disposal
at plants represented by Model 1 (Missouri plants) involve
transporting dewatered granulated slag by dump truck or rail car
to the disposal area. Two plants, which generate 51 percent of
the total Missouri slag, haul slag by truck; the third plant,
which generates 49 percent of the total slag, hauls slag by rail
(4-20,4-21,4-22). The slag is then simply piled on the disposal
site. The two non-Missouri smelters transport molten slag by
ladle truck to the disposal area (4-23,4-24). About 65 percent
of the non-Missouri slag is handled in this manner. At the
disposal site, the molten slag is poured over already solidified
slag, where it cools, and forms a solid, fused mass. The Model 2
integrated smelter/refinery, representing 33 percent of the
non-Missouri slag, granulates its slag, as do the Model 1 plants;
however, it does not dewater the slag, but pumps it as.a slurry
to the disposal site (4-25). The slag slurry is then placed on
the existing slag pile and is dewatered as the water percolates
through the pile. The disposal area is located adjacent to the
company's concentrator tailings pond. The granulation water
flows into this pond which also receives mine drainage,
concentrator tailings, and discharges from lead and zinc smelter
impoundments. Currently the water is not recycled but is
discharged. The remainder of the non-Missouri slag is generated
by the refinery and is disposed of by a private contractor
(4-26). Because no cost information is available on this
4-49
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specific operation, it is assumed that removal and ultimate
disposal of the refinery slag by the contractor would cost
approximately $10 per ton.*
Not all of the slag produced is stockpiled in the disposal
area. Model 1 plants recycle two-thirds of the total slag
produced, and Model 2 plants process all slag through a zinc
fuming furnace. Some of the remaining slag is sold or donated
for various purposes such as winter road sand, railroad ballast,
roofing material, concrete aggregate, and decorative uses.
Disposal by sale or donation is much more prevalent at Model 2
plants. At least two of them donate or sell slag, but the
quantities involved are not available (4-25,4-27). One of the
Model 2 smelters reported that its slag pile is mined by a
private company and sold for railroad bed fill, concrete
aggregate, and decorative uses (4-23). For the past several
years slag has been removed from the pile faster than it has been
added, and the pile is at a minimum. In addition to mining at
the present slag dump, an abandoned slag dump has been mined and
little slag remains at that location.
Sale of slag from Model 1 smelters amounts to only 0.8
percent of the total slag disposed of by these three plants
(4-20,4-21,4-22). Donation of granulated slag for uses such as
winter road sand has been halted in recent years at all three
* PEDCo engineering estimate.
4-50
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plants because of pressure resulting from purported environmental
contamination. Such uses of slag, if found to be environmentally
acceptable, could be a viable alternative control practice; they
do not represent a significant factor in current disposal
systems.
Past and current disposal practice does entail use of
significant quantities of slag in onsite construction — for
example, as fill and base material, in road construction, and in
land reclamation. Because of this relatively common practice,
some of the slag reported as being disposed of is scattered about
the plant site and is not placed in the disposal area.
Depending upon plant operations, previously stockpiled slag
may be mined to be reused as a sulfur diluent in the sintering
process (Model 1 plants) or reprocessed in the zinc fuming
furnace if its zinc content is high enough (Model 2 plants). In
either case, although slag is reprocessed, the bulk of it
eventually returns to the slag pile minus whatever metal fraction
is recovered. Although the reprocessing of slag to recover its
metal content is not a significant control practice in terms of
the total volumes of slag, it should be noted that retreating a
slag in a pyrometallurgical process may alter its composition and
characteristics.
Current Control of Miscellaneous Slurries—All three Model 1
\
plants have surface impoundments, although not all require
dredging (4-20,4-21,4-22). Neither of the Model 2 smelters nor
4-51
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the Model 2 refinery have impoundments (4-23,4-24). The
integrated Model 2 smelter/refinery operates a small surface
impoundment that requires periodical dredging (4-25,4-28).
In current practice the impoundments are dredged of their
accumulated solids on an 'as needed' basis. This accumulation in
the impoundments results from the settling of carryover slag in
the granulation water, acid plant blowdown, and plant clean-up
and runoff. Dredging is done with common equipment at
frequencies from once per year to once every 3 years or longer.
The dredged material is either placed beside the impoundment and
later trucked to the disposal area or trucked immediately. Some
of this material may be recycled to sintering if it contains
enough metals.
Cost of Current Controls
The total cost of current solid waste control practices of
primary lead smelters and refineries are calculated on the basis
of unit costs, as presented in Appendix C. Each of the Model 1
lead plants was visited by the PEDCo project team, who also
toured one Model 2 smelter and contacted the remaining three
plants by phone. This thorough coverage of the primary lead
industry allowed the project team to calculate control costs for
each plant represented by the model; these costs are not
presented in this report to avoid disclosure of proprietary
information. Therefore, the total costs for all plants
represented by each model are presented. Detailed information
4-52
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concerning the compilation of these costs is presented in the
following sections along with the cost values.
Both capital and annual costs, in 1978 dollars, are given
for each model category (Tables 4-10, and 4-11). Capital costs
are subdivided into three main categories for the purposes of
discussion: land costs, construction costs, and equipment costs.
Annual costs also are allotted to these three categories and to
the additional category of operation and maintenance.
Current Control Costs for Model 1—The cost of current solid
waste control at all Model 1 plants is developed in this section.
Model 1 (Figure 4-2) represents three integrated
smelter/refineries that process Missouri concentrates. The major
solid waste produced at these plants is granulated blast furnace
slag; the other solid waste, minor in comparison, is dredge
spoils from impoundments receiving the miscellaneous slurries.
Costs for controlling these two wastes are presented in Table
4-10.
The land cost covers only the amount of land required for
actual solid waste control. This includes the slag disposal area
and the area required for surface impoundments. Based upon the
Model 1 slag production rate of 47,000 tons (42.6 Mg) per year
and an assumed specific gravity of 0.8, the approximate volume of
3
slag generated during 1 year is estimated to be 2.0 million ft
3
(57 km ). For a slag pile 50 ft (15.2 m) high, about 1 acre (0.4
ha) per year is required for disposal. Over a 20-year life
approximately 20 acres (8.1 ha) is required for slag disposal;
4-53
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TABLE 4-10
TOTAL COST OF CURRENT CONTROLS FOR
ALL PLANTS
REPRESENTED BY MODEL 1
(1978 dollars)
Misc.
Slag control
slurries control
Capital Cost
Land
58,300
40,100
Construction
Survey
22,500
15,500
Site preparation
12,000
8, 200
Haulage road
31,200
Haulage rail
103,000
Surface impoundments
134,200
Equipment
408,000
46,700
Subtotal
635,000
244,700
Contingency (10%)
63,500
24,500
TOTAL CAPITAL COST
698,500
269,200 967,700
Annual Cost
Land
7, 500
5,200
Construction
21,700
20,300
Equipment
73,100
8,400
Operation and maintenance
Personnel
112,400
31,100
Maintenance
29,800
7,000
Fuel and electricity
16,200
5,500
Taxes
1,600
1,100
Insurance
7,000
2,700
TOTAL ANNUAL COST
269,300
81,300 350,600
4-54
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TABLE 4-11
TOTAL COST OF CURRENT CONTROLS FOR ALL PLANTS
REPRESENTED BY MODEL 2
(1978 dollars)
Misc.
Slag control slurries control
Capital Cost
Land 58,300 1,200
Construction
Survey 22,500 450
Site preparation 12,000 250
Haulage road 31,200
Surface impoundments 9,000
Equipment 181,700 1,700
Subtotal 305,700 12,600
Contingency (10%) 30,600 1,300
TOTAL CAPITAL COST 336,300 13,900 350,200
Annual Cost
Land 7,500 150
Construction 8,500 1,250
Equipment 32,600 300
Operation and maintenance
Personnel 276,000 2,700
Maintenance 11,700 300
Fuel and electricity 86,800 500
Taxes 1,600 50
Insurance 3,400 150
Private contrator haulage
cost 75,000
TOTAL ANNUAL COST 503,100 5,400 508,500
4-55
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this value was used in calculating costs for Model 1. The cost
of the total area of land required is based on the unit land cost
of $971 per acre ($2400 per ha) as detailed in Appendix C.
The land requirements for surface impoundments at Model 1
plants are based on site visits, which led to an estimated
requirement of 41.3 total acres (16.7 ha). This acreage is not
divided evenly among the three Model 1 plants. Land costs are
annualized over a 20-year period at 10 percent interest with no
resale value.
Construction costs for current disposal practices include
costs for survey, minimal site preparation (clearing and
grubbing), construction of a slag haulage road or rail system,
and excavation, forming, and grading of a surface impoundment.
Costs of survey and site preparation are based on unit costs of
$375 per acre ($925 per ha) and $200 per acre ($500 per ha), as
detailed in Appendix C. A slag haulage distance of 0.5 mile (0.8
km) is assumed for each plant in the Model 1 classification.
Construction of haulage roads at $31,200 per mile ($19,400 per
km), as detailed in the Appendix, is applied to two Model 1
plants; construction of rail line at $206,000 per mile ($128,000
per km) is applied to the remaining Model 1 plant.
Cost of construction of the surface impoundments is based on
the method described in the Appendix and applied to the
impoundments by size. Surface impoundments at Model 1 lead
plants consist of four 2.75-acre (1.1-ha), one 4.0-acre (1.6-ha),
4-56
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one 5.0-acre (2.0-ha), and one 5.75-acre (2.3-ha) impoundments.
The cost of all construction is annualized over a 20-year period
at 10 percent interest.
The equipment used in solid waste handling and control at
Model 1 plants includes haulage and dredging equipment and
granulated slag dewatering towers. Dewatering towers are
relatively simple structures consisting of an elevated silo with
a bucket elevator. Granulated slag and granulation water are
placed in the tower, where dewatering is done by gravity. Slag
is then loaded into the haulage equipment, which consists of
20-ton (18-Mg) dump trucks at two plants and a rail engine,
100-ton (90.7 Mg) hopper cars, and crane at the third plant.
Dredging equipment consisting of a dredging crane and front-end
loader is used at all plants having impoundments. A usage
factor, the percent of time a piece of equipment is used for
solid waste handling or control practices, is applied to the unit
capital and annual equipment costs to account for specific usage
of multiuse equipment. For dump trucks, rail hopper car, and the
dewatering towers, 100 percent usage is assumed. Usage factors
for the rail engine and rail crane are assumed to be 10 percent
and 80 percent respectively. Dredging equipment usage is based
upon the amount of solids carried to the lagoons annually in the
miscellaneous slurries. A density of approximately 1 ton per
3
cubic yard (1.2 Mg per m ) is assumed for the dredge spoils. A
3
dredging rate of approximately 35 cubic yards (26.8 m ) per hour
4-57
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is also assumed.* Based on the solids generation factor for
miscellaneous slurries, plant production, and the specified
dredging rate, the time required for dredging was estimated.
From this time requirement were derived usage factors as a
percentage of time equipment is in use. Equipment costs are
annualized over a 10-year period at 10 percent interest with no
resale value.
Annual costs of operation and maintenance (O&M) include
personnel, repair and maintenance, and fuel and electricity.
Annual personnel costs were calculated from the hourly rates
presented in Appendix C. Time requirements for haulage,
dredging, and supervisory time are based on solid waste quantity
data. Assumptions were made regarding the time required per slag
3 3
haul trip (1 hour)t and dredging rate [35 yd per h (26.8 m per
h)] so that personnel hours could be estimated. Repair and
maintenance costs are calculated as a percent of capital cost: 3
percent of surface impoundment construction costs and 5 percent
of equipment and all other construction costs. Fuel costs are
based on the consumption rates detailed in Appendix C and the
hours of operation described for personnel costs. Costs of
electricity are based on horsepower ratings and hours of
operation for such equipment as pumps, at a rate of $0.06 per
kilowatt-hour.
* Adapted from Office of Solid Waste. Assessment of
Industrial Hazardous Waste Practices.
t PEDCo engineering estimate.
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Current Control Costs for Model 2—This section describes
the costs of current solid waste control as practiced at primary
lead smelters and refineries categorized under Model 2. Plants
represented by Model 2 include two smelters, one refinery, and
one integrated smelter/refinery. The major solid waste produced
at these facilities is furnace slag; they also produce minor
quantities of refinery slags and dredge spoils. The costs are
those estimated to be incurred through the control of the wastes
by the current practices described earlier.
The Model 2 land cost includes only the land required for
actual solid waste control. Based on Model 2 slag production
3 3
rates and an assumed density of 240 lb per ft (3.9 g per cm )
(4-29), it is estimated that a site of 20 acres (8.1 ha) would be
adequate over a 20-year life for Model 2 plants, as for Model 1
plants. Land cost attributable to disposal of miscellaneous
slurries from Model 2 plants is for one relatively small surface
impoundment requiring an estimated 1.2 acres (0.5 ha). The cost
of the total land area required is based on a unit land cost of
$971 per acre ($2400 per ha) and is annualized over a 20-year
period at 10 percent interest with no resale value, as was Model
No. 1 land cost.
Construction costs for current solid waste disposal
practices include costs of the survey; minimal site preparation
(clearing and grubbing); construction of a slag haulage road or
rail system; and excavation, forming, and grading of the surface
4-59
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impoundment. Costs of the survey and site preparation are based
on unit costs of $375 per acre ($925 per ha) and $200 per acre
($500 per ha) respectively, as detailed in Appendix C.
The distance from the point of solid waste generation to the
control facility is assumed to be 0.5 mile (0.8 km) at all
plants. Of the three Model 2 plants that stockpile waste onsite,
two transport molten slag in a ladle truck and one granulates the
slag and pumps it as a slurry to the control facility. Cost of
the slag haulage road at the two plants is included in the
construction costs, and cost of the slag slurry pipeline is
included in the equipment costs. A road construction cost of
$31,200 per mile ($19,400 per km) is used in this calculation.
The cost of constructing the small surface impoundment is based
on the method described in Appendix C.
The cost of construction is annualized over a 20-year period
at 10 percent interest.
The equipment used at Model 2 plants for solid waste control
includes slag haulage equipment (two plants) dredging equipment
(one plant), and a slag slurry pipeline (one plant). Haulage
equipment consists of ladle trucks, and dredging equipment
(dredging crane and front-end loader). The slag slurry pipeline
is a pressure pumping system, as detailed in Appendix C.
Equipment usage factors as discussed for Model 1 are used in
equipment calculations for Model 2.
Equipment costs are annualized over a 10-year period at 10
percent interest with no resale value.
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Annual operation and maintenance (O&M) costs include
personnel, repair and maintenance, fuel and electricity. These
costs are calculated for Model No. 2 plants on the same basis as
described for Model 1.
Total Cost of Current Controls—The estimated total costs
for the lead industry are $1,317,900 capital cost and $859,100
annual cost (Table 4-12). With annual industry production of
612,000 tons (555 Mg) of refined lead, the annual cost of the
current system is approximately $0.0007 per pound ($0.0015 per
kg) of metal product. With annual generation of 699,200 tons
(634 Mg) of solid waste (Table 4-5), the annual cost of the
current system is approximately $1.23 per ton ($1.11 per Mg) of
solid waste.
Alternative Solid Waste Control Practices
This section deals with alternative solid waste control
practices that may be needed to provide adequate environmental
and health safeguards. If such a system of controls were
implemented, the current facilities would not be upgraded but
would be closed; the new facilities would be opened within plant
property lines. For this reason no costs are calculated or
presented for upgrading existing sites, costs for closing
existing sites are, however, calculated and presented.
The alternative controls are all deemed technically and
economically feasible. Not all of them, however, would
necessarily be required of any one facility. The alternative
system includes relatively intensive site selection, extensive
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TABLE 4-12
TOTAL COST OF CURRENT SOLID WASTE CONTROL FOR THE PRIMARY
LEAD SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 967,700 350,600
Model 2 350,200 508,500
Total 1,317,900 859,100
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site preparation, ground sealing, a seepage collection system,
runoff collection and diversion ditches, wells for monitoring
groundwater, flood protection dikes, access control (fencing),
closure of existing sites, and postclosure monitoring and
maintenance.
The need for these alternative controls would be assessed on
a site-specific basis. Some practices, such as advanced leachate
control, would not be needed for example, where the groundwater
is very deep or the native soils, geology, and topography provide
sufficient natural protection from groundwater contamination.
The need for control and the degree of control required can be
assessed only by detailed analysis of a specific site.
Although the alternative system includes all of the current
practices, any of them may require greater effort or more
extensive application in the alternative system. For example,
site preparation in the current systems includes only clearing
and grubbing of the disposal area, whereas the alternative system
specifies clearing and grubbing, removal of topsoil, and grading
to better prepare the area for disposition of solid wastes.
To date, little effort has been expended in site selection,
which is one of the most important aspects of the alternative
system. It involves thorough assessment of such factors as
drainage and runoff; proximity to natural waters, both surface
and underground; type, chemistry, and permeability of soils;
availability of land for site expansion; environmental
4-63
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sensitivity of areas; aesthetics; and long-term land use. The
requirement for comprehensive site selection will increase the
immediate costs of disposal, but will minimize the long-term cost
and the adverse effects associated with indiscriminate site
selection.
Groundwater is monitored in the alternative system to detect
contamination resulting from solid wastes. The specified system
incorporates six monitoring wells within the plant line. At
least one is to be installed hydraulically upgrade of the solid
waste control facility. Two are to be installed immediately
adjacent to and hydraulically downgrade of the solid waste
control facility. The three remaining wells also are to be
installed hydraulically downgrade and within plant boundaries.
Although the RCRA Criteria do not specifically require
closure of current disposal sites, closure is necessary to ensure
the continuing and long-term maintenance of site integrity.
Closure consists of covering the solid waste with soil and
revegetating to prevent erosion. The soil cover consists of a
relatively impermeable bottom layer covered by a layer of soil
capable of supporting indigenous vegetation. Total thickness of
the cover is 2 ft (0.6 m). Monitoring and site maintenance of
the closed site are to be carried out for 20 years after closure.
Alternative Control of Slag—Several alternative practices
are specified for slag control, beginning with the substantial
effort for site selection. Site preparation is expanded to
include not only clearing and grubbing but also removal of
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topsoil and grading. A perforated pipe drain field is placed
beneath the slag disposal area to provide detection and
collection of seepage. A 6-in.-(15-cm-) thick soil-cement pad is
constructed on the disposal area above the drain field. The pad
provides structural support and is graded for runoff and seepage
collection. Both the pad and drain field provide groundwater
protection. Ditches both upgrade and downgrade of the site are
provided to control surface water. Details of drain fields,
soil-cement pads and ditching are provided in Appendix C. A sump
and pump are installed to handle and transport collected water to
the surface impoundments or for use as makeup water. The
alternative controls include no process changes.
In addition to the provisions for groundwater protection, a
monitoring system is also needed. For this study, it is assumed
that the control site for slag and the surface impoundments for
miscellaneous slurries are relatively close to one another and
that the well system can monitor the entire area. For this study
the depth of the wells is designated as 100 feet (30.5 m); thus a
greater number of shallower wells could be dug for the same cost.
The alternative system provides for sampling and analysis and for
maintenance of the wells. Alternative slag disposal practices
emphasize protecting surface and groundwaters. Control of either
granulated or solidified molten slag should not require control
of fugitive air emissions.
Alternative Control of Miscellaneous Slurries—Under the
alternative system, surface impoundments are lined with a
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-4
synthetic liner 30-mil (7.6 x 10 m) thick and are covered with
0.5 yard (0.46 m) of protective soil. Beneath the impoundment
and its liner is located a perforated pipe drain field, as for
the slag disposal area. Both of these practices provide positive
control of seepage from the surface impoundments and thus control
or prevent groundwater pollution. As with the slag disposal
area, increased efforts are applied to site selection and site
preparation. The monitor wells will indicate the extent, if any,
of groundwater contamination from the disposal site, which
includes any surface impoundments.
Costs of Alternative Controls
This section presents capital and annual costs of the
alternative controls (Tables 4-13 and 4-14), together with
detailed information on their derivation. Capital costs are
grouped into three main categories: land costs, construction
costs, and equipment costs. Annual costs also are grouped into
these three categories, with an additional operation and
maintenance category. Although PEDCo has calculated separate
costs for each individual plant represented by the models, these
costs are not presented, as a safeguard for proprietary
information. Therefore, total costs are given for all plants
represented by each model.
Many of the alternative control practices do not apply to
any specific waste but to the entire control facility. These
practices are site selection monitoring wells, sampling and
analysis of water samples, closure, postclosure operations, and
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TABLE 4-13
COST OF ALTERNATIVE SOLID WASTE CONTROL FOR ALL PLANTS
REPRESENTED BY MODEL 1
(1978 dollars)
Slag control
Misc.
slurries control
Capital Cost
Site selection
89,700
89,700
Land
69,900
48,000
Construction
Survey
27,000
18,500
Site preparation
38,200
26,100
Haulage road
31,200
Haulage rail
103,000
Soil cement pad
592,400
Surface impoundments
134,200
Drain system
115,200
76,200
Impoundment liner
602,800
Liner cover
147,800
Ditching
37,900
Monitor wells
24,750
24,750
Flood dike
146,600
Fence
111,000
78,000
Equipment
408,000
46,700
Closure operation
335,600
111,800
Post closure operations
606,000
202,000
Subtotal
2,736,450
1,606,600
Contingency (15%)
410,450
241,000
TOTAL CAPITAL COST
3,145,900
1,847,600
4,994,500
Annual Cost
Site selection
12,000
12,000
Land
9,400
6, 500
Construction
165,100
149,100
Equipment
76,500
8,800
Operation and maintenance
Personnel
112,400
31,100
Maintenance
85,500
59,300
Fuel and electricity
18,600
6, 300
Sampling and analysis
30,000
30,000
Closure operations
45,200
15,000
Postclosure operations
81,500
27,200
Taxes
2, 300
1, 200
Insurance
31,500
18,500
TOTAL ANNUAL COST
670,000
365,000
1,035,000
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TABLE 4-14
COST OF ALTERNATIVE SOLID WASTE CONTROL FOR ALL PLANTS
REPRESENTED BY MODEL 2
(1978 dollars)
Slag control
Misc.
slurries control
Capital Cost
Site selection
Land
Construction
Survey
Site preparation
Haulage road
Soil-cement pad
Surface impoundment
Drain system
Impoundment liner
Liner cover
Ditching
Monitor wells
Flood dike
Fence
Equipment
Closure operations
Post closure operations
Subtotal
Contingency (15%)
TOTAL CAPITAL COST
89,700
69,900
27,000
38,200
31,200
592,400
115,200
37,900
24,750
73,300
151,000
181,700
443,000
800,000
2,675,250
401,300
3,076,600
89,700
1,400
525
750
9,000
1,100
16,000
3,700
24,750
3, 000
1,700
4,400
8,000
164,000
24,600
188,600 3,265,200
Annual Cost
Site selection 12,000
Land 9,400
Construction 142,000
Equipment 34,100
Operation and maintenance
Personnel 276,000
Maintenance 66,300
Fuel and electricity 99,800
Sampling and analysis 30,000
Closure operations 59,600
Postclosure operations 107,600
Taxes 2,000
Insurance 30,800
Private contractor haulage
expense 75,000
TOTAL ANNUAL COST 94 4,600
12,000
200
7,900
300
2,700
1,800
600
30,000
600
1,100
50
1,900
59,150 1,003,800
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fencing. The cost of site selection, monitor wells, and sampling
and analysis are distributed equally among the waste types. The
costs of closure and postclosure practices are distributed among
waste types in proportion to waste quantities. Cost of fencing
is distributed in proportion to area requirements for each waste
type. These cost distributions are applied to both models.
To ensure that sufficient funds for closure will be
available at the end of the life of the solid waste control
facility, the alternative system specifies establishment of a
trust fund when the facility is opened. This fund, with accrued
interest, will cover the cost of closure. A trust fund is also
established to provide capital for postclosure operations.
Alternative Control Cost for Model 1—Model 1 (Figure 4-2)
represents the three integrated smelter/refineries that process
Missouri concentrates. Costs of alternative controls for plants
represented by Model No. 1 are presented in Table 4-13. These
values include costs for the controls currently practiced plus
the additional items required for alternative control practices.
Site selection is one of the most important aspects of
alternative practice. A realistic estimate of the
order-of-magnitude cost entails three basic assumptions: it
requires 1 engineer-year, it requires a hydrogeological survey of
three potential sites, and the site is selected on the basis of a
final report. The total cost of this activity is estimated at
$59,800 per plant site, as detailed in Appendix C. For this
study it is assumed that the cost of site selection is the same
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for all plants regardless of model. The costs are annualized
over a 20-year period and are equally distributed among waste
types.
The land area required for alternative control practices is
assumed to be 20 percent greater than that required for current
practices. This additional area is needed for the placement of
devices such as diversion and collection ditches, monitoring
wells, and sumps and pumps. The cost of the land upon which a
flood dike is constructed is included in the cost of the dike.
The per-acre land cost again is $971 per acre ($2400 per ha) and
cost is annualized over a 20-year period at 10-percent interest
with no resale value.
Construction costs for the alternative controls again
include costs of haulage ways, surface impoundments, and
dewatering towers. Additional construction costs incurred in
implementing alternative practices include the soil-cement pad
beneath the slag disposal area, the diversion ditch upgrade from
the slag disposal area and the collection ditch downgrade, the
synthetic liner for surface impoundments with protective soil
cover, and the drain fields to collect seepage beneath slag pad
and impoundments.
The 6-inch-(15-cm-) thick soil-cement slag control pad
provides structural support for the slag and minimizes seepage;
it is graded toward the collection sump. The drain system
beneath the slag disposal area consists of parallel perforated
pipe placed at 50-foot (15-m) intervals, with a collection pipe
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running the length of one side of the field. The collection pipe
empties into the sump, from which it is pumped to the impoundment
system. The drain system can be used to detect and quantify
seepage and also provides a means of collecting seepage for
treatment, depending on its composition. Diversion and
collection ditches are each 1.5 times the length of one side of
the slag disposal area. Diversion ditches channel surface runoff
from adjacent land around the disposal area, collection ditches
collect any runoff from the disposal area, which is routed to the
drain field sump. For a 20-acre (8.1 ha) slag disposal site, the
following costs were calculated, as detailed in Appendix C:
soil-cement pad - $164,600; drain system - $38,400; sump and
pump - $3,100; ditching - $12,600.
Alternative control practices for the surface impoundments
-4
include a synthetic liner 30 mils thick (7.6 x 10 m), covered
with 1.5 ft (0.47 m) of protective soil, and a drain field as
described for the slag disposal area. The drain field is square,
with sides equal to the diameter of the surface impoundment. A
synthetic liner was selected to control seepage rather than a
natural clay liner in an effort to standardize cost across the
industry. The cost of a clay liner would vary considerably from
a plant in Missouri, where adequate clay soil may be available
onsite, to a plant in the Southwest, which may be required to
purchase and transport clay a considerable distance. The
synthetic liner standardizes purchase and installation costs, and
circumvents any potential problems of reactivity that may be
4-71
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encountered with natural soil materials with seepage from a slag
disposal site or impoundment. As with the slag disposal area,
the drain field beneath the surface impoundment allows detection
and collection of seepage and provides an extra measure of
protection against groundwater contamination. Other construction
costs incurred in the alternative control system at Model 1
plants include fencing and flood diking. Fencing is provided
around the entire control facility. The total fencing cost is
distributed proportionately among the waste types on the basis of
land area requirements for each. It is assumed that two of the
three Model 1 plants would require flood diking around the slag
control area. The dike is of the same dimensions as the
impoundment dike, as detailed in Appendix C. Construction costs
are annualized over a 10-year period at 10 percent interest.
Because the alternative controls involves no process
changes, all equipment costs are the same as for the current
system. Personnel costs also are the same. Repair and
maintenance are more expensive in the alternative system because
construction costs are higher, most notably for the soil-cement
pad, drain fields, and impoundment liners. Electricity costs are
somewhat greater, reflecting the greater number of pumps. Costs
of the alternative system include an additional $20,000 per year
per plant for the sampling from the monitor wells and analysis of
the samples. This includes an amount for repair and maintenance
of the well system. As with the cost of the monitor wells, this
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annual sampling and analysis cost is divided equally among the
waste types.
Alternative Control Costs for Model 2—Model 2 (Figure 4-3)
represents four plants, two smelters, one refinery, and one
integrated smelter/refinery, all of which process lead-bearing
materials from a wide variety of sources. The alternative
control costs for all plants in this model category, summarized
in Table 4-14, consists of those incurred in the current control
system and additional costs incurred by implementing the
alternative control practices.
The costs incurred in site selection are the same as those
for Model 1 plants, $59,800 per plant site. This cost, is
distributed equally among the waste types and is annualized over
a 20-year period. Land area requirements and costs in the
alternative system are assumed to be 20 percent greater than
those of the current system. This additional area is required
for placement of waste control or management devices. The
per-acre land cost is the same as current costs at $971 per acre
($2400 per ha) and is annualized over a 20-year period at 10
percent interest with no resale.
Because the slag control facilities are assumed to be the
same for all plants regardless of model classification,
construction costs and details of the haulage road, soil-cement
slag pad, drain system, collection and diversion ditches, sumps,
and pumps are the same for Model 2 as for Model 1.
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The alternative system for surface impoundments as described
for Model 1 applies also to Model 2. Fencing encloses the entire
control facility at each plant. The fencing cost is distributed
proportionately among the waste types on the basis of land area
requirements. It is assumed that one of the four Model 2 plants
would require flood diking. The flood dike surrounds the slag
control area and is of the same dimensions as the impoundment
dike (Appendix C).
All construction costs are based on unit cost and
construction details presented in Appendix C. Construction costs
are annualized over a 10-year period at 10 percent interest.
Again, because no process changes are involved, equipment
costs in the alternative systems are the same as in the current
systems.
Personnel costs also are the same. Repair and maintenance
are more expensive because of the increased construction costs,
notably for the soil-cement pad, drain fields, and impoundment
liners. Electricity costs are higher because of the pumps for
drain field sumps. An additional cost of $20,000 per year per
plant is allocated for sampling and analysis of samples from the
monitor wells and for repair and maintenance of the well system.
This cost is divided equally among waste types.
Total Cost of Alternative Controls—The total costs
estimated for alternative controls in the lead industry are
$8,259,700 capital cost and $2,038,800 annual cost (Table 4-15 ).v
With an annual industry production of 612,000 tons (555 Gg), the
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TABLE 4-15
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS IN THE PRIMARY
LEAD SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 4,994,500 1,035,000
Model 2 3,265,200 1,003,800
Total 8,259,700 2,038,800
4-75
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annual cost of the alternative system is approximately $0.0017
per pound ($0,008 per kg) of refined lead. With annual solid
waste generation of 699,200 tons (634 Gg), the annual cost of the
alternative system is approximately $2.92 per ton ($2.64 per Mg)
of solid waste.
Cost of Closing Existing Solid Waste Control Sites
All lead plants currently have onsite areas for solid waste
disposal. These disposal sites contain some or all of the solid
wastes described earlier, depending on the processes employed and
the pollution control devices used at the plants over past years.
The current and past practices for solid waste control at these
disposal sites may not provide adequate protection of human
health and the environment according to RCRA standards;
therefore, these sites may be declared open dumps, and operators
will be required to close or upgrade them.
For this study it is assumed that all existing onsite
disposal areas fail to meet RCRA criteria, that these sites will
be closed rather than upgraded to meet RCRA requirements, and
that new onsite disposal facilities that comply with RCRA
standards will be constructed. The costs of closure for existing
sites are estimated to determine the potential capital and annual
cost that may eventually be incurred by the lead industry.
To estimate the order-of-magnitude cost of closure, one must
calculate the quantity of waste that has accumulated at the site.
Industry sources indicate that the total accumulation at the
three plants represented by Model 1 is approximately 1,883,000
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tons (1708 Gg) (4-20,4-21,4-22). The total accumulation to date
at the four plants represented by Model 2 is estimated to be 10
million tons (9070 Gg).*
The surface area of the slag pile at each plant is estimated
on the basis of the quantity of solid waste present. Closure
costs are based on covering the slag pile with 2 ft (0.61 m) of
soil, compacting the first 6 in. (0.15 m), grading the area, and
vegetating the soil cover. Unit costs for these activities are
3
as follows: excavation and placement of cover - $1.60 per yd
3 3 3
($1.22 per m ); compaction - $2.14 per yd ($1.63 per m );
2 2
grading - $0,065 per ft ($0,006 per m ); and vegetating and
fertilizing $1,000 per acre ($2,470 per ha).
The total capital cost for closure of existing solid waste
facilities is estimated to be $1,057,200, and the total annual
cost, $123,700 (Table 4-16).
Analysis of Solid Waste Control Costs
The cost analysis includes calculation of the total
incremental cost of solid waste control that would be incurred by
the lead smelting and refining industry in implementing the
alternative controls and closing existing disposal sites (Table
4-17). This total incremental cost is based on classification of
wastes as nonhazardous and hazardous. In this report slag is
considered nonhazardous and miscellaneous slurries (dredge
spoils) are considered hazardous as discussed earlier. The total
* PEDCo engineering estimate.
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TABLE 4-16
TOTAL COST OF CLOSING EXISTING CONTROL SITES IN THE PRIMARY
LEAD SMELTING AND REFINING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 589,800 69,000
Model 2 467,400 54,700
Total 1,057,200 123,700
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TABLE 4-17
CURRENT, ALTERNATIVE, CLOSURE, AND INCREMENTAL CONTROL COSTS FOR
THE PRIMARY LEAD SMELTING AND REFINING INDUSTRY
(1978 dollars)
Current Alternative * Closure^ Total incremental^
Waste type* Capital Annual Capital Annual Capital Annual Capital Annual
Nonhazardous 1,034,800 772,400 6,223,500 1,614,600 854,900 100,000 6,171,900 957,200
(slag)
Hazardous 283,100 86,700 2,036,200 424,150 64,400 7,600 1,827,100 346,200
(Dredge spoils)
Total 1,317,900 859,100 8,259,700 2,038,800 919,300 107,600 7,999,000 1,303,400
=====^==^=^^==^===^^=z=::^^=====^======^^===
I
^ * Classification of solid waste as hazardous or nonhazardous is based on EPA's listing of hazardous
waste in the December 18, 1978, Federal Register (43 Fed. Reg. 58946).
+ Alternative control costs include the cost of the alternative controls together with the cost of
closing and maintaining the alternative disposal sites.
Closure costs represent the cost of closing existing solid waste disposal sites.
' Incremental costs- equal the sum of the cost of alternative controls and costs of closure minus the
costs of current controls.
-------
incremental annual cost for control of nonhazardous solid wastes
is $957,200; this represents about 73 percent of the total
incremental cost of controlling both classes of wastes (Table
4-17).
The fraction of the incremental cost of controlling
nonhazardous solid waste that can be attributed to the RCRA
Criteria is estimated by grouping the incremental costs into two
categories: state-standard-induced (cost of complying with
existing state regulations) and Criteria-induced (cost of
complying with RCRA Criteria that are more stringent than state
standards). The Criteria-induced costs represent those
incremental solid waste control costs that cannot be attributed
to current state regulations. Provisions of state regulations
were determined by consulting an analysis of state regulations
and the proposed Federal Criteria (4-17).
The major costs to the lead industry that could potentially
be attributable to the RCRA Criteria would derive from four
criteria, those dealing with environmentally sensitive areas
(flood plains), surface water, groundwater and safety (access).
Costs entailed in closure and postclosure maintenance of both
existing and alternative control facilities are also attributed
to RCRA. These costs cannot be directly attributed to any one
criterion but are indirectly attributable to all. For purposes
of this study all closure costs were assumed to be attributable
to the Criteria since existing state regulations do not contain
closure and postclosure requirements. Other criteria, those
4-80
-------
dealing with wetlands, permafrost, critical habitat, sole-source
aquifers, air, disease vectors, explosive gases, fires, toxic
gases, and bird hazards, are considered inapplicable to the
domestic primary lead smelting and refining industry.
All states with lead industry except one have regulations
covering flood plains (Idaho is the sole exception), surface
water, groundwater, and access. The Criteria-induced costs
therefore consist of those costs attributable to closure of
nonhazardous existing solid waste facilities, closure and
postclosure maintenance of alternative controls, and the cost of
flood plain protection in Idaho (Table 4-18).
The Criteria-induced incremental annual cost for control of
nonhazardous wastes is $420,500; this represents 44 percent of
the total incremental annual cost of nonhazardous solid waste
control (Tables 4-18 and 4-17).
For the purpose of comparison, the capital cost required to
bring the lead/zinc industry into full compliance with air and
water pollution control regulations is $149 per ton ($135 per Mg)
of production, of which $123 (83 percent) is for air and $26 (17
percent) is for water (4-30). The Criteria-induced incremental
capital cost developed in this study (Table 4-18) amounts to
approximately $5.01 per annual ton ($454 per Mg) of refined lead
product.* For reference, the average capital cost per annual ton
* Based on an annual refined lead production of 612,000 tons
per year (Table 4-1).
4-81
-------
TABLE 4-18
CRITERIA-INDUCED CONTROL COSTS FOR THE PRIMARY LEAD SMELTING
AND REFINING INDUSTRY*
(1978 dollars)
State
Idaho
Missouri
Montana
Nebraska
Texas
Total
Capital
670,400
1,356,300
560,600
0
481,500
3,068,800
Annual
89,500
194,600
72,800
0
63,600
420,500
* These values include additional costs for closure
of accumulated nonhazardous solid waste, closure and post-
closure maintenance of alternative nonhazardous solid waste
systems and Criteria-induced costs for states whose solid
waste regulations do not satisfy the Criteria.
4-82
-------
for a mine-mill-smelter in the copper, lead, and zinc industries
is estimated at about $1,500 (1975 constant dollars) (4-30). On
the basis of the cost estimates in this study, the
Criteria-induced nonhazardous incremental cost is minor in
comparison with costs of complying with air and water pollution
control regulations in the domestic primary lead smelting and
refining industry.
4-83
-------
REFERENCES FOR SECTION 4
4-1. Mineral Industry Surveys. Lead industry in May 1978. U.S.
Department of the Interior, Bureau of Mines, Washington,
D.C. August 23, 1978.
4-2. Ryan, J.P., and J.M. Hague. Lead - 1977. Mineral commodity
profile - 9. U.S. Department of the Interior, Bureau of
Mines, Washington, D.C. December 1977.
4-3. Battelle Columbus Laboratories, Columbus, Ohio. Energy
use patterns in metallurgical and nonmetallic mineral
processing (phase 4 - energy data flowsheets,
high-priority commodities). U.S. Department of the
Interior, Bureau of Mines Open File Report 80-75.
1975. 192 pp.
4-4. Institute of Gas Technology. Study of industrial uses of
energy relative to environmental effects. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, July 1974. pp XI1-XI14.
4-5. Charles River Associates, Incorporated, Boston,
Massachusetts. Economic impact of the proposed EPA
National Ambient Air Quality Standard for lead. The
Lead Industries Association. March 1978.
4-6. Personal Communication. Mr. Rathjen, Bureau of Mines to
M. Taft, PEDCo. October 1978.
4-7. Charles River Associates, Incorporated, Boston,
Massachusetts. Lead, copper, and zinc price forecasts
to 1985. Volume I and II. U.S. Environmental
Protection Agency. Washington, D.C. August 1978.
4-8. PEDCo Environmental, Inc., Cincinnati, Ohio. Environmental
assessment of the domestic primary copper, lead, and
zinc industries. U.S. Environmental Protection Agency,
Industrial Environmental Research Laboratories. Contract
No. 68-03-0537. September 1978. 387 pp.
4-84
-------
4-9. Battelle Columbus Laboratories, Columbus, Ohio.
Nonferrous metals technical awareness bulletin. U.S.
Environmental Protection Agency, Industrial Environmental
Research Laboratory, Cincinnati, Ohio, Vol. 1, Issue 5,
January/February 1978.
4-10. Haver, F.P. Recovery of lead from lead chloride by
fused-salt electrolysis. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C. Report of
Investigation 8166. 1976.
4-11. Phillips, T.A. Economic evaluation of a leach -
electrolysis process for recovering lead from galena
concentrate. U.S. Department of the Interior, Bureau
of Mines. Information Circular 8773. 1978.
4-12. Scheiner, B.J., et al. Chlorine - Oxygen leaching of
complex sulfide concentrates. TMS paper No. A 77-86.
Society of Metallurgical Engineers, American Institute
of Mining, Metallurgical and Petroleum Engineers, Inc.,
New York, New York. 1977.
4-13. McKay, J.E. Lead. In: Kirk-Othmer Encyclopedia of
Chemical Technology. Second Edition V.12. New York,
John Wiley & Sons, Inc., 1967. pp. 207-247.
4-14. Cottrill, C.H., and J.M. Cigan, ed. Extractive metallurgy
of lead and zinc: AIME world symposium on mining and
metallurgy of lead and zinc, Volume II. New York, The
Metallurgical Society of AIME, 1970.
4-15. Office of Air and Water Programs. Development document
for interim final effluent limitation guidelines and
proposed new source performance standard for the
secondary aluminum smelting subcategory of the aluminum
segment of the nonferrous metals manufacturing segment
of the nonferrous metals manufacturing point source
category. October 1973.
4-16. U.S. Bureau of Mines. Minerals and materials, a monthly
survey. Washington. December 1978.
4-17. Office of Solid Waste. Comprehensive sludge study
relevant to Section 8002 (g) of the Resource
Conservation and Recovery Act of 1976 (PL 94-580).
V.l. Environmental Protection Contract No. 68-02-3945.
Washington.
4-85
-------
4-18. Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refining
industry, V.2. EPA Publication SW-145.C.1. National
Technical Information Service. Springfield,
Virginia. 1977.
4-19. Federal Register. Hazardous waste. Proposed guidelines
and regulations and proposal on identification and
listing. V.43. No. 243. p. 58946. Washington. U.S.
Government Printing Office, December 18, 1978.
4-20. Personal communication: B. Hoye, PEDCo, with Missouri lead
plant personnel. Site visit. September 26, 1978.
4-21. Personal communication: B. Hoye, PEDCo, with Missouri lead
plant personnel. Site visit. September 27, 1978.
4-22. Personal communication: B. Hoye, PEDCo, with Missouri lead
plant personnel. Site visit. September 28, 1978.
4-23. Personal communication. D. Sass, PEDCo, with non-Missouri
lead smelter personnel. Site visit. September 27,
1978.
4-24. Personal communication. B. Hoye, PEDCo, with non-Missouri
lead smelter personnel. Phone conversation. November
13, 1978.
4-25. Personal communication. J. Greber, PEDCo, with non-Missouri
lead plant personnel. Phone conversation. December 14,
1978.
4-26. Personal communication. B. Hoye, PEDCo, with non-Missouri
lead plant personnel. Phone conversation. November 13,
1978.
4-27. Texas Department of Water Resources. Unpublished data,
1978.
4-28. Personal communication. R. Brown and M. Wilkinson,
Calspan Corporation with non-Missouri lead plant
personnel. Site visit. September 11-12, 1974.
4-29. Weast, R.C., ed. Handbook of chemistry and physics. 48th
ed. Cleveland, The Chemical Rubber Company, 1967.
4-30. MacDonald, B.I., and M. Weiss. Impact of environmental
control expenditures on copper, lead and zinc producers.
Mining Congress Journal, 64(l):45-50, January 1978.
4-86
-------
SECTION 5
PRIMARY ZINC SMELTING AND REFINING INDUSTRY
Industry Characterization
Although the primary zinc industry has experienced a variety
of problems in recent years, it still is a viable industry in the
United States. Between 1941 and 1971, the United States led in
the world production of zinc. In 1977 the United States ranked
only fourth among the zinc-producing countries and consumed about
one-fifth of the world supply. Outdated equipment, environmental
problems, production cutbacks, falling prices, labor strikes, and
lower consumption have led to the reduction of domestic
production and to closure of several smelters in the past 10
years. The industry has responded to these problems by
retrofitting older plants with new environmentally and
economically sound processes and by constructing two new
electrolytic plants.
The domestic primary zinc industry consists of mining,
concentrating, smelting, and refining segments. Generally, ore
is mined and concentrated at one location and then the ore
concentrate is transferred to smelters for production of zinc,
zinc oxide, or both. Production of zinc from concentrates can
follow two general routes, hydrometallurgical (or electrolytic)
5-1
-------
and pyrometallurgical. Hydrometallurgical processing involves
dissolving of the zinc in a sulfate solution followed by
electrolytic deposition of zinc. Pyrometallurgical processing
involves distillation in retorts and furnaces. In both methods
the concentrate must be roasted to remove sulfur before further
processing.
Industry Description
Raw Materials—Zinc concentrates produced by the
beneficiation of various zinc-containing ores are the main input
material for production of primary zinc. Concentrates from
various sources and locations differ in zinc content and also in
the amounts and types of impurities they contain. The
concentrates are usually stored in separate bins at the zinc
smelters and are combined to form a specific blend before being
fed to the process.
Zinc concentrates are recovered from various types of ores.
Of an estimated 450,000 tons (408.0 Gg) of zinc mined
domestically in 1977, 53 percent was produced from zinc ores, 22
percent from lead-zinc ores, 18 percent from lead ores, and 7
percent from all other ores (5-1). Tennessee, Missouri, New
York, Colorado, and New Jersey were the five states leading in
mine production. In addition to domestic ores, about 123,000
tons (112. Gg) of zinc in the form of ores and concentrates was
imported and processed at U.S. smelters.
Zinc deposits normally contain the zinc sulfide mineral,
sphalerite, often called zinc blende, blend, or jack. Sphalerite
5-2
-------
often occurs in association with galena, chalcoprite, and other
sulfide ores. Wurtzite, a polymorph of sphalerite, is more
stable at high temperatures. Most other zinc minerals are formed
as oxidation products of these minerals.
The zinc content of some pure ores can reach 67.1 percent of
the ore; usually, however, the zinc content ranges between 1.7
and 16 percent in ores that are economically extracted from the
mine.
In addition to zinc, the most common constituents of the
ores are iron and cadmium. Small quantities of germanium,
gallium, indium, and thallium are associated with sulfide
deposits.
Several other raw materials are used to produce primary
zinc. These include agents that are added to promote or enhance
the various process reactions. For example, coke or coal is used
as a reducing agent at pyrometallurgical plants, and zinc dust is
used at hydrometallurgical plants for removal of impurities.
Other materials are sometimes added to the process for recovery
of zinc values. These include, for example, particulates and
sludges collected in pollution control devices, cleanup
materials, and worn construction materials such as refractory
brick. These residuals are generally recycled within plants but
are sometimes transferred from one plant to another.
Production and Capacity—Zinc slab is the principal product
of zinc smelting. Other major products include zinc diecasting
alloys, brasses, zinc oxides, and other chemicals. Important
5-3
-------
byproducts of primary zinc production include copper, silver, and
gold; minor byproducts are sulfuric acid and cadmium. Recovery
of these byproducts is necessary for the economical extraction of
the zinc metal. Sulfuric acid is produced at most zinc smelters
from the effluent of S02 control systems. Smelter operators
usually sell the acid at a loss unless the smelter is located
near a market. Because the cadmium market is currently
depressed, the amount of cadmium recovered from smelter dusts and
slags is very small and continues to decrease. Residues
containing germanium, thallium, indium, and gallium are collected
at the smelter, then shipped elsewhere for metal recovery.
Slab zinc production in 1977 was 500,000 tons (453.6 Gg),
with a value of $326 million (5-2). These production figures
indicate that the industry utilized 75.8 percent of total plant
capacity. The Bureau of Mines estimates that domestic zinc slab
production will increase to 800,000 tons by the year 2000 (5-3).
Based on this estimate, the average annual growth rate for zinc
slab production would be 2.065 percent. By use of this factor
production values during the 1980 to 1995 period can be
estimated, as shown in Table 1.
In 1974 the average annual price of refined zinc increased
sharply to $0.4130 per pound ($0.9027 per kg) (5-1). During the
past 4 years the price steadily decreased from the 1974 high. In
1977 the average annual price was $0.3260 per pound, and in
August 1978 the average monthly price was $0.3116 per pound. The
1977 domestic prices for copper, silver, and gold as reported by
5-4
-------
TABLE 5-1
U.S. PRIMARY ZINC INDUSTRY STATISTICS*
(tons except as noted)
Production
Mine, recoverable zinc 449,620
Smelter, slab zinc 500,000
1980 531,600
1985 588,800
1990 652,200
1995 722,400
2000+ 800,000
Imports
Ores and concentrates, 122,809
(dutiable zinc content)
Slab zinc 576,735
Exports
Slab zinc 235
Consumption
Slab zinc 1,101,765
Ores (recoverable zinc content) 95,339
Average U.S. producer price, slab zinc (S/lb) 0.326
Total value of annual prodution
Slab zinc (millions $) 326
* Mineral industry surveys. Zinc industry in June 1978.
U.S. Dept. of the Interior, Bureau of Mines, Washington, D.C.
September 6, 1978. All values are 1977 statistics, unless
otherwise noted.
+ Personal communication. V.A. Cammarota, Jr., Bureau of
Mines, to M. Taft, PEDCo. October 6, 1978.
Note: Metric conversion table is given in front matter.
5-5
-------
the Bureau of Mines were $0.6678 per pound, $4.62 per troy oz,
and $148.31 per troy oz.
In 1977 the total U.S. smelter capacity was 660,000 tons
(599.74 Gg), of which electrolytic plants produced 352,000 tons
(319. Gg) and vertical retort facilities produced 308,000 tons
(219. Gg) (5-1). The zinc metal is distributed to industries in
41 states, with Ohio, Pennsylvania, Illinois, Michigan, New York,
and Indiana each consuming over 100,000 tons (91 Gg).
Eight U.S. primary smelters closed in the past 10 years
because of environmental problems, outdated equipment, and lack
of concentrate (5-4). Domestic consumption currently exceeds
mine production. These factors have led to an increasing
reliance on imports and government stockpiles.
The 1977 smelting charges ranged from $90 to $140 per ton
($99 to $154 per Mg) of concentrate (5-1). U.S. production costs
for a hypothetical electrolytic zinc plant with capacity of
120,000 tons (109. Gg) per year were estimated at $115 per ton
($127 per Mg) of zinc slab. The average capital investment
requirement from mining to primary metal rose 37.9 percent during
the period from 1972 to 1975 (5-1).
Companies—The primary zinc industry currently consists of
six companies that operate six primary zinc smelters as listed in
Table 2. All of the smelter production of primary slab zinc is
in Pennsylvania, Illinois, Oklahoma, Idaho, and Texas (5-5). A
new electrolytic plant in Clarksville, Tennessee is to begin
production early in 1979. In 1978 approximately 6,000 people
5-6
-------
TABLE 5-2
U.S. PRIMARY ZINC PRODUCERS*
Company and location
Description
Capacity
(tons/year)
First year
of operation1'
Product
Amax, Inc
East St. Louis, 111.
Asarco, Inc.
Corpus Chnsti, Tex.
The Bunker Hill Co.
Silver King, Idaho
National Zinc Co.
Bartlesville, Okla.
Electrolytic
Electrolytic
Electrolytic
Electrolytic
82,000
108,000
108,000
55,000
1929
1942
1928
1976
Slab zinc, cadmium, zinc suflate
and sulfuric acid
Slab zinc, zinc alloys, zinc sul-
fate, cadmium, and sulfuric acid
Slab zinc, zinc alloys, cadmium,
and sulfuric acid
Zinc dust, zinc slab, zinc alloys,
cadmium, cobalt cake, copper/
lead/nickel cake, and lead silver
residue
New Jersey Zinc Co.
Palmerton. Pa.
St. Joe Minerals Corp.
Monica, Pa.
Pyrometallurgical 113,500
Pyrometallurgical 250,200
1899
1930
Slab zinc, zinc alloys, zinc dust
and pellets, zinc oxide, ferro-
alloy, and sulfuric acid
Slab zinc, zinc alloys, zinc oxide,
cadmium, ferosilicon, mercury,
and sulfuric acid
Jersey Miniere Co.
Clarksville, Tenn.
Electrolytic
90,000
1978
Slab zinc, cadmium, sulfuric acid
* Sources: PEDCo Environmental, Inc. Environmental assessment of the domestic primary copper, lead, and zinc
industries. U.S. E.P.A. Contract No. 68-03-2534. September 1978.
U.S. Environmental Protection Agency. Draft effluent guidelines, primary lead smelting and refining. June
1974.
+ These are the original construction dates, but most of these facilities, except Clarksville, have been
rebuilt and expanded.
Note Metric conversion table is given in front matter.
-------
were employed in lead-zinc mining and milling and 4,000 people in
zinc primary smelting and refining (5-3). Many of the companies
producing primary zinc are vertically integrated and therefore
are involved in two or more process segments. Often these firms
own interests in processing of other valuable metals, such as
copper lead, silver, and gold; these interests sometimes make
mining and processing of the zinc ores economically feasible.
Energy Consumption—In 1973 the primary zinc industry
consumed approximately 92 trillion Btu (97 TJ) of energy (5-6).
Of the three processes in use the electrothermic process consumes
the most energy (72.57 x million Btu per net ton, 84.4 GJ per
Mg), followed by the vertical retort process (65.06 million Btu
per net ton, 75.6 GJ per Mg), and the electrolytic process (60.17
million Btu per net ton, 70 GJ per Mg). The average, therefore,
was 65 million Btu per net ton (75.6 GJ per Mg) (5-6). Between
1967 and 1972 the efficiency of energy utilization increased by 8
percent, primarily because of the closing of inefficient
horizontal retorts (5-7).
To reduce energy consumption, the United States industry
could adopt the Imperial Smelting Process (ISA), which has been
applied successfully in Europe in both zinc and lead production.
This process is comparable to that using the lead blast furnace,
except that the tuyeres project inside the line of the water
jackets to improve heat economy and the air blast is preheated in
alloy-tube preheaters fired by furnace gas (5-7).
5-8
-------
Outlook—Zinc is an international commodity whose trade is
influenced by government actions such as tarrifs and other price
controls. The U.S. Bureau of Mines estimates that domestic
demand will be 1.29 million tons (1.17 Tg) in 1985 and 1.7
million tons (1.45 Tg) in 2000 (5-1). They attribute the high
demand to technological improvements and to requirements for new
equipment and machinery.
Zinc producers are more skeptical. Domestic consumption of
slab zinc declined 27 percent from 1973 to 1977 (5-8). The
decline is attributed to the depressed economic conditions that
began in 1974 and extended through 1976, and to the loss of
market to other products. As an example of the later, the
automobile industry, a major consumer of zinc die castings,
reduced the amount of zinc used in 1978 model cars by 50 percent.
Auto manufacturers have substituted lighter-weight materials such
as aluminum, plastics, and high-strength steel in an effort to
increase mileage ratings.
Although consumption of slab zinc decreased about 400,000
tons (362 Gg) during the 1973 to 1977 period (5-8), the imports
of slab zinc for domestic markets increased by approximately
160,000 tons (145 Gg) in this interval.
Zinc producers believe that the industry is at an all-time
low (5-9). The producers petitioned the International Trade
Commission to investigate the industry and to recommend
restrictions on imports. After a 6-month investigation, the
5-9
-------
Commission concluded that the industry's main problems were due
to factors other than imports. Therefore, according to law, they
could not recommend placing tarrifs on imports.
World production during the period from 1973 to 1976 trended
downwards, generally paralleling domestic slab zinc production.
In 1977 world production increased by 3 percent while U.S.
production decreased by 10 percent (5-8). World production is
expected to continue to increase.
As mentioned earlier, in 1974 the price of zinc reached an
all-time high and then declined to the present price. This
fluctuation was caused by a supply shortage in 1974, followed by
a period of oversupply and depressed economy. The price remained
fairly constant in 1976, and prices of imported and domestic slab
zinc differed only slightly. In 1977 the differential widened as
both prices began a downward trend, with U.S. prices averaging 4
percent higher than import prices.
It is difficult to predict the future price of zinc. The
industry is now operating at a loss (5-9). In 1977 the domestic
zinc industry lost $4,125,000 before taxes; this includes the six
primary and two secondary producers of zinc slab (5-8). This
loss indicates that prices must rise relative to demand. A
recent study conducted by Charles River Associates generated
forecasts of copper, lead, and zinc prices through 1985 (5-10).
Two scenarios (one for moderate growth and one for rapid growth)
were developed on the basis of assumptions regarding the ratio of
capacity to demand. Both scenarios project modest increases in
5-10
-------
the paths of U.S. zinc prices. In constant 1978 dollars, the
moderate-growth scenario projects an increase from $0,368 per lb
($0,810 per Kg) in 1977 to $0,332 per lb ($0,730 per Kg) in 1985.
The rapid-growth scenario projects an increase from $0,368 per lb
($0,810 per Kg) in 1977 to $0,346 per lb ($0,761 per Kg) in 1985.
In current dollars the 1985 price of zinc is predicted to be
$0,506 per lb ($1.11 per Kg) with moderate growth and $0,528 per
lb ($1.16 per Kg) with rapid growth.
Although a new electrolytic zinc plant is about to start
production, major expansions seem doubtful under present market
conditions (5-9). This could have an adverse effect on the U.S.
balance of payments because demand may outstep plant capacity and
thus cause an increase in imports.
Recently St. Joe Zinc Company announced plans to conduct a
detailed technical and economic feasibility study of construction
of an electrolytic zinc refinery (5-11). This refinery may
replace St. Joe's outmoded electrothermic facility in Monaca,
Pennsylvania, where numerous production breakdowns have occurred
in recent months. Speculation is that St. Joe may form a
partnership with Exxon to ensure a constant supply of feed (5-7).
The known U.S. reserves of zinc ores consist of 24 million
tons (21.8 Tg), with major deposits in the "New Lead Belt" of
Missouri and in Tennessee (5-1). In 1976 Exxon announced the
discovery of a massive zinc sulfide deposit (38.5 million tons,
or 35 Tg) near Crandon, Wisconsin. It is projected that
production at the Exxon mine will begin in the 1980's and could
5-11
-------
eventually amount to 25 percent of U.S. production (5-12).
Environmental concerns and the economic climate could delay and
possibly prevent the mining of this deposit.
Development of new zinc alloys could open new markets for
the primary zinc industry. Research is being conducted on
aluminum and zinc alloys to substitute for sheet steel
applications, on alloys for use in mold castings, and on
zinc-rich paints for corrosion resistance.
Other industry developments may include increased
automation, a pressure leaching process to reduce sulfur dioxide
emissions, and increased use of galvanizing for protection
against corrosion, along with the introduction of zinc-based
batteries in automobiles.
Process Description
Two major processes are used to produce zinc domestically:
hydrometallurgical (or electrolytic) and pyrometallurgical (or
pyrolytic). Hydrometallurgical processing involves dissolving
the zinc in a sulfate solution followed by electrolytic
deposition of zinc. The electrolytic refining allows the
processing of lower-grade zinc ores than does pyrometallurgical
processing and is used at five domestic plants.
Pyrometallurgical processing takes advantage of the
relatively low boiling point of zinc, which is distilled in
furnaces called retorts. An advantage of pyrolytic over
electrolytic refining is that secondary and scrap zinc can be
used. Although pyrolytic processing is practiced at only two
5-12
-------
- pnci'innws
Lwoiuh CJtBBOMTE OB
Q LIQUID WASTE
9 ATMOSPHERIC EMISSION
SOLID HASTE
Figure 5-1. Flow
(numbers correspond to
chart depicts primary zinc smelting and refining
process numbers in text).
-------
facilities in the United States, it represents nearly half of
early-1978 zinc capacity. Figure 5-1 is a representative flow
sheet of the domestic zinc industry.
Roasting—All concentrates received at zinc plants are
roasted to drive off sulfur and convert the zinc sulfide (ZnS) in
the concentrate to an impure zinc oxide called calcine (Process
No. 1). Zinc oxide is the compound needed for zinc recovery by
both processes. Roasting converts the zinc sulfide to zinc oxide
by burning the concentrate in the presence of air or oxygen.
Roasting also volatilizes some of the trace metal impurities,
such as cadmium, lead, and arsenic, and removes water from the
concentrate. The following reactions occur during roasting
(5-13):
2ZnS + 302 2ZnO + 2S02 (1)
2S02 + 02 -»• 2S03 (2)
ZnO + S03 ZnS04 (3)
Because zinc cannot be recovered from zinc sulfide, roasting is
carried as far as is economically feasible to generate the
maximum amount of zinc oxide.
Roasters emit particulates, mainly metal fume. These
particles contain recoverable metal and are collected for further
processing. All solids that enter the roaster are collected and
used in the next process operation; thus the roasting operation
directly produces no solid wastes. The conversion to zinc oxide
produces a roaster off-gas stream containing enough sulfur
dioxide to permit sulfur recovery as sulfuric acid by
5-14
-------
conventional means. All domestic smelters operate plants to
produce sulfuric acid. Acid production results in a weak acid
waste stream from the scrubbing columns that clean the off-gas
(5-14). This acid plant "blowdown" is neutralized and thickened,
and the solids are allowed to settle in ponds. The collected
solids constitute a solid waste if they are not recycled.
The domestic industry uses three types of roasters: the
multiple-hearth roaster, the suspension or flash roaster, and the
fluidized-bed roaster. The multiple-hearth roaster, the oldest
type, is gradually being phased out of operation. Only two
plants now use this roaster, and one effectively uses it to
remove lead from concentrates before additional roasting and to
volatilize mercury in the concentrate (5-15). In the flash
roaster an oxidizing atmosphere volatilizes sulfur as sulfur
oxides. Concentrate is suspended in an air stream and blown into
a hot combustion chamber where sulfur is burned. About 60
percent of the concentrate is carried out with the off-gas and
collected in the air pollution control equipment (5-14). In the
fluid-bed roaster, the newest type, the concentrate is
desulfurized on a bed supported by an air column. Fluid-bed
roasters are highly instrumented and are likely to be used in new
electrolytic refineries.
Hydrometallurgical Refining—Hydrometallurgical or
electrolytic refining produces zinc of high purity. All new
domestic zinc plants are likely to be hydrometallurgical.
5-15
-------
Electrolytic refining consists of leaching, filtering,
purification, and electrolysis.
The first step in electrolytic refining is separation of the
zinc from the gangue material in the calcine by leaching with a
dilute sulfuric acid solution, spent electrolyte (Process No. 2).
Both single-leach and double-leach processes are in use. In
single leaching calcine is added to spent electrolyte so that the
solution remains slightly acidic after all of the soluble zinc
has been dissolved (5-13). Either lime, ground limestone, or
more calcine is then added to neutralize the solution and
precipitate some of the impurities in the liquor. This process
is not often used because it must be carefully controlled to
maximize zinc recovery and minimize loss of acid (5-14). In
double leaching the first, or neutral, leach dissolves the easily
soluble zinc and removes some of the impurities. Enough calcine
is added to ensure excess zinc oxide to make the solution basic
and cause precipitation of such impurities as iron, silica, and
alumina. The residue from the first leach is then processed in
an acidic leach to achieve maximum recovery of zinc. After the
residue is removed, the liquor from the acid leach is returned to
the first leach. No solid waste results from leaching because
the liquor and residue are sent to the filtering step.
The leach slurry is filtered to separate the zinc-bearing
liquor from the insoluble residue in preparation for further
processing (Process No. 3). As the slurry is forced through the
filter, solids collect in a filter cake, which contains all the
5-16
-------
acid-insoluble elements such as lead, indium, gold, and
platinum-group metals, as well as silica, alumina, and silicates
of iron, aluminum, and calcium (5-14). The filter cake is washed
with water and then cleaned from the filter. Disposal of the
solids depends on the concentration of recoverable metals.
Usually the residue contains enough lead and precious metals to
permit economical recovery of the metals at a lead smelter. When
concentrations of valuable metals are low, the residue could
become a solid waste to be discarded in a residue pile, but this
occurs rarely. Solid waste from filtering is usually limited to
the worn-out filter cloths.
Impurities must be removed from the leach liquor before
reduction because leaching dissolves many soluble compounds other
than zinc that interfere with the reduction of zinc to metal by
electrolysis (Process No. 4). A variety of reagents are added to
precipitate the impurities. Various reagents and steps are used
for purification, depending on the impurities present in the ore
concentrate. Most smelters add zinc dust, often in the form of
"blue powder" (a combination of zinc dust and zinc oxide), after
the specialized separation steps (5-14). Addition of zinc causes
the precipitation of cadmium, copper, and several other elements.
The final steps remove other metals, including arsenic, antimony,
cobalt, germanium, nickel, and thallium, which interfere with the
deposition of zinc. Solids precipitated during purification are
filtered from the solution and are recycled onsite or offsite for
metal recovery.
5-17
-------
Purified leach solution, or electrolyte, is added to the
electrolytic cells, where zinc is recovered and the dilute
sulfuric acid leach solution is regenerated (Process No. 5). As
purified solution is added to the electrolyte circuit, some of
the spent electrolyte is removed and recycled to leaching.
Electrolysis takes place in rectangular tanks, or cells,
containing closely spaced metal plates. Lead plates, containing
0.75 to 1.0 percent silver, are the anodes, and aluminum plates
are the cathodes. The electrolyte is circulated slowly through
the cells. Water dissociates at the anode, releasing oxygen gas,
and zinc is deposited at the cathode. The hydrogen ions produced
by water dissociation remain in solution and regenerate the
sulfuric acid in the electrolyte. Every 24 to 48 hours the
aluminum cathodes are removed from the cell and the zinc is
stripped off. After the stripping, the aluminum sheets are
chemically cleaned and returned to the cell, and the cell is
returned to normal operation. Sludge that accumulates in the
cell during operation is removed periodically (5-14). This
sludge is usually discarded and thus represents a solid waste
from electrolysis.
Zinc metal stripped from the cathode is dried, then melted
in a furnace in preparation for casting into marketable shapes
(Process No. 6). Flux is added to the zinc in the furnace to
retard oxidation at the surface and to collect any oxides that do
form. The flux and oxides form a dross that floats on top of the
molten zinc. Dross is skimmed from the surface of the zinc and
5-18
-------
centrifuged to remove entrained zinc. Recovered metal is used to
make zinc dust for purification or is returned to the melting
furnace. The residue from metal recovery is the solid waste from
this process.
Molten zinc from the melting furnace is cast into marketable
shapes on a casting wheel or belt (Process No. 7). The zinc is
either cast pure into bars or blocks or is alloyed with other
metals and cast. Molten zinc can also be used to make zinc dust
and zinc oxide. This process generates no solid wastes.
Pyrometallurqical Smelting—In pyrometallurgical processing
the physical properties of the zinc concentrate must be altered
to provide efficient zinc recovery. Pyrometallurgical processing
entails the following steps: sintering, retorting, refining, and
casting.
For pyrometallurgical processing the furnace feed must be a
hard, permeable mass that is relatively free of impurities. To
develop the desired characteristics for furnace feed the calcine
is sintered (Process No. 8). The sinter feed is a mixture of
calcine, recycled zinc-bearing materials, and coal compacted into
pellets with water or zinc sulfate to minimize dusting. Silica
sand and other special agents may also be added to give required
physical characteristics. Domestic smelters use a downdraft
sinter machine that is a modification of an original Dwight-Lloyd
design. Sinter is fed onto a moving grate and fired. The grate
moves into a combustion chamber, where the calcine burns
autothermally and is fused into a hard, permeable sinter. The
5-19
-------
downdraft operation of the machine causes the volatile elements
in the calcine to concentrate in the bottom layers of the sinter.
The zinc-rich upper layer is sliced off, and the lower layer is
recycled to the process.
Sintering produces a high-volume stream containing too
little sulfur dioxide for conventional recovery. The gas stream
is cleaned of particulates and vented to the atmosphere.
Particulates from sintering contain most of the cadmium (80 to 90
percent) and lead (70 to 80 percent) present in the sinter feed
(5-14). These metals are recovered as byproducts; thus sintering
produces no solid wastes. Cadmium is leached from the particles
in an acidic solution and recovered at the zinc plant. The
residue is sent to a lead smelter.
The zinc oxide in the sinter is reduced with carbon in a
retort to produce zinc metal (Process No. 9). Two types of
retorts are in operation: the vertical retort and the
electrothermic retort. These operate in much the same manner,
the main difference being the power supply to the furnace.
Preheated feed of sinter and coal or coke is fed into the top of
the retort. Inside the retort the temperature reaches 1300° to
1400°C or more, and the following reactions take place (5-13):
ZnO + CO -» Zn(g) + CC^ (actual reduction step)
CC>2 + ¦* 2 CO (regeneration of CO)
Because of zinc's low boiling point (906°C) it is volatilized as
soon as it is formed. In this way the zinc is purified by
separating it from the gangue material in the calcine. The zinc
5-20
-------
vapor, carbon monoxide formed in the furnace, and other minor
gases are drawn out of the furnace into a condensor, where zinc
is condensed from the gas stream. The remaining gases, mainly
carbon monoxide, are cleaned in a venturi scrubber to remove
"blue powder," which is small globules of zinc metal coated with
zinc oxide. Because the zinc oxide prevents the globules from
coalescing in the bath, they float on top or are entrained in the
gas stream. After the gases have been cleaned they can be used
as supplementary fuel inside the plant.
Solid wastes from the retorts are the residue from zinc
recovery and the blue powder contained in the scrubber slurry.
The solid residue contains a variety of metals, which may be
processed for recovery depending on the concentrations. The
residue is finally disposed of in a slag dump. "Blue powder" in
the scrubber slurry is allowed to settle in a pond and then
dredged for recycling to the process.
Zinc from smelting may need further purification for some
commercial uses. The zinc is purified by distillation in a
graphite retort. Distillation to produce high-grade zinc
produces no solid waste, since all solids are recycled for metal
recovery.
Zinc oxide, an important product of the primary zinc
industry, is produced directly from sinter (Process No. 10).
Three types of furnace are used in the United States: the
grate-type furnace, the rotary or Waelz kiln, and the
electrothermic furnace. All of these operate by reducing the
5-21
-------
zinc oxide in the sinter to zinc vapor and ducting the vapor to a
combustion chamber, where it is oxidized. Solid wastes from this
process are similar to those from the retort and are handled in a
like manner.
Cadmium Processing—All zinc refineries produce cadmium as a
byproduct. Cadmium is always present in zinc ores, and
cadmium-rich dusts, sludges, or other materials are produced
during primary zinc processing. Cadmium is recovered from these
materials by processing analagous to zinc recovery; leaching,
purification, and either electrolysis or retorting.
Solids resulting from cadmium processing are the residues
from leaching, retorting, and electrolysis. Cadmium-containing
materials are leached to solubilize the cadmium. The solid
residue is high in metal values and is processed for recovery.
In purification of the leach solution, zinc powder is used to
precipitate the cadmium, which is then filtered from solution,
dried, and sent to metal recovery. The leach solution containing
most of the zinc is recycled to sintering in pyrometallurgical
plants or to electrolysis in electrolytic plants. When extra
purification steps are necessary, they produce small quantities
of solids, which are usually recycled. Cadmium is purified in
the graphite retorts at pyrometallurgical plants and in
electrolytic cells at hydrometallurgical plants. Solid residues
from the retorts are a solid waste; this is a low-volume
material, however, that is often returned to sintering to recover
5-22
-------
metal values. Electrolysis also produces some solid residue that
is recycled to recover metal values.
Solid Waste Characterization
Sources and Quantities of Solid Waste
This section describes the sources and quantities of solid
wastes generated by the primary zinc smelting and refining
industry. In this analysis two model plants have been developed
to represent the primary zinc industry. Model 1 represents the
four primary plants that produce zinc by electrolytic processes.
Model 2 represents the two primary plants that produce zinc by
pyrometallurgical techniques. The rationale for these two models
is the inherent differences of the two production methods and the
resultant differences in solid waste generation.
The sources of solid waste produced at primary zinc plants
were identified in the literature and verified by the PEDCo
project team in visits to the zinc plants. The quantities of
solid wastes presented herein are based on waste generation
factors that are expressed as tons of waste generated per ton of
zinc produced. The generation factors in turn are based on
values reported in the literature and on information obtained
during the plant visits.
As at most primary nonferrous metal smelters, particulates
collected by air pollution control devices are continuously
recycled to the zinc smelting process. These particulates are
generally high in metal content and are recycled to recover this
5-23
-------
fraction; for this reason, particulates are not included in the
calculated quantities of solid waste. Likewise, most residues or
byproducts generated at these plants are not solid waste. They
are shipped to other smelters for metal recovery or are recycled
to the process; in either case the operation is conducted on a
current basis, with little if any temporary storage or
stockpiling. These residues are shown as byproducts and are not
included in the quantification of solid wastes.
Detailed flow diagrams are presented for both model plants.
The sources of the solid wastes generated and the quantities of
wastes are indicated both in the diagram and in the text
discussion. The flow diagrams do not give quantities for
materials other than solid waste, i.e. intermediate products.
The emphasis here is on values for solid wastes rather than a
complete material balance.
As a means of standardizing the analysis, all model plants
are assumed to operate 350 days per year and 24 hours per day.
All plants also are assumed to operate at 76 percent of capacity.
Waste generation factors are thus based on production and not
plant capacity.
Model 1: Electrolytic Zinc Production—The Model 1 plant
(Figure 5-2) is assumed to produce 67,000 tons (60.8 Gg) of
refined slab zinc annually. This model represents four
electrolytic zinc plants at which actual production rates range
from 41,800 tons (37.9 Gg) to 82,100 tons (74.5 Gg) of slab zinc
per year. These four plants account for approximately 268,300
5-24
-------
A
cn
NJ
en
1 ofmo
NOTE- NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR.
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 5-2. In the primary zinc industry Model 1 represents electrolytic
plants.
-------
tons (240 Gg) of the total annual primary zinc production, or
about 49 percent of the industry total. Process flow at the
plants is very similar, with some variation.
The sources of solid waste generated by the Model 1 plant
are (1) filtration of the leach solution, (2) cleaning of the
electrolysis cells, (3) collection and treatment of acid plant
blowdown and miscellaneous slurries, (4) treatment of preleach
residue (this last operation occurs at only one plant).
The preleach process, used by one electrolytic plant with an
annual production of 62,300 tons (56.5 Gg), is depicted as an
alternative process (dotted line) on the model plant diagram
(Figure 5-2). Preleaching removes excess magnesium from the
incoming concentrates. Magnesium acts much like zinc, but is not
electrolyzed and accumulates in the system; therefore the
concentrates having high magnesium levels must be preleached
before further processing. The preleach step involves the
reaction of sulfuric acid and a bleed stream from the acid plant
with a portion (up to 100%) of the incoming concentrates to
solubilize the magnesium. The insoluble concentrate is separated
and continues through the process. The solubilized material and
the acidic preleach solution enter a lined surface impoundment,
from which they are pumped to a wastewater treatment plant
(WWTP). Sludge that settles in the impoundment is periodically
removed and placed in the WWTP. This sludge, together with
sludge produced from neutralization and precipitation reactions
in the WWTP, is continuously removed and hauled to an offsite
5-26
-------
landfill operated by a private contractor. At the plant that
uses preleaching the WWTP sludge also contains solids from acid
plant blowdown, anode slimes (electrolysis cell cleanings), and
miscellaneous slurries. The available information indicates that
the total quantity of this WWTP sludge generated annually is 9400
tons (8.5 Gg), which indicates a waste generation factor of 0.14
(ton of waste produced per ton of product zinc). This brief
discussion of the preleach process used at one plant is intended
to clarify the process flow diagram and to specify the quantity
of solid waste generated at one operation.
All plants represented by Model 1 treat the roaster off-gas
in contact sulfuric acid plants to control sulfur dioxide. The
plants produce salable acid and a bleed stream (acid plant
blowdown) that must be neutralized. Treatment of the acid plant
blowdown generates an estimated 1400 tons (1.3 Gg) of sludge per
year at the model plant. The waste generation factor based on
this value is 0.021.
All plants represented by Model 1 also generate a waste
stream of anode slimes from cleaning of the electrolytic cells.
Anode slimes consist of gangue material that has passed through
the earlier process steps but was not plated out, or
electrolyzed, in the electrolysis step. It is estimated that
anode slimes make up some 670 tons (608 Mg) of the annual solid
waste produced by the model plant. The waste generation factor
for anode slimes is estimated at 0.01 ton per ton of zinc
production.
5-27
-------
Unlike the other plants one of the four electrolytic zinc
plants produce a leach residue that is not shipped as a byproduct
to a pyrometallurgical smelter (usually a lead plant). The
annual generation of this goethite residue is 41,800 tons (38
Gg). Because this leach residue is a waste rather than a
byproduct at this plant and is stockpiled onsite, it is included
in the solid waste totals. In addition a new electrolytic plant
scheduled to be on-line in 1979 will probably also produce a
goethite residue. Generation of goethite at this facility would
then be 24,600 tons (22.3 Gg) per year. The three remaining
plants ship their leach residue to pyrometallurgical smelters as
a byproduct. This leach residue, called goethite, is produced at
a rate of 24,100 tons (21.9 Gg) per year at the model plant. The
waste generation factor for goethite residue is 0.36 (ton of
waste per ton of zinc produced).
Application of the waste generation factors cited herein to
the total production of the plants represented by Model 1, yields
the quantities of solid waste currently generated by the
electrolytic zinc plants (Table 5-3).
Model 2; Pyrometallurgical Zinc Production—The Model 2
plant (Figure 5-3) is assumed to produce annually some 120,000
tons (109 Gg) of zinc metal and 36,000 tons (32.6 Gg) of zinc
oxide. This model represents two pyrometallurgical zinc plants
with a combined annual production rate of about 261,100 tons (237
Gg) of zinc metal. These plants account for approximately 51
percent of the total production of zinc metal by the primary zinc
5-28
-------
TABLE 5-3
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY ZINC PLANTS
REPRESENTED BY MODEL 1*
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Anode slimes
0.01
2,600
"Goethite" residue
0. 36
15,100
Acid plant blowdown
0.021
5,600
Dredge spoils
0.031
8,200
Waste water treatment
with preleach
sludge
0. 09
5,600
Waste water treatment
without preleach
sludge
0.038
3,100
Total
40,200
* Totals do not include wates from a new plant which came on line
late in 1978. This plant will increase annual solid waste generation
by about 70,000 tons per year.
Note: Metric conversion table is given in front matter.
-------
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NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
y "TURNACE RES 31!E N
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Figure 5-3. In the primary zinc industry Model 2
represents pyrometallurgical plants.
(continued)
5-30
-------
ROASTING
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PRECIPITATION
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NOTE NUMERICAL VALUES EXPRESSED IN THOUSANDS OF TONS PER YEAR
BROKEN LINES REPRESENT ALTERNATIVE MATERIALS FLOW ROUTES
METRIC CONVERSION TABLE IS GIVEN IN FRONT MATTER
Figure 5-3•
(continued)
-------
industry. Although the two plants represented by this model use
the same basic processes, they differ greatly in the quantities
of solid waste generated and in the ultimate disposal or control
of the waste. These variations are shown on the process flow
diagram (Figure 5-3) as alternative processes or pathways,
depicted by dotted lines.
The sources of solid waste at the Model 2 plant are (1)
collection and treatment of acid plant blowdown, (2) production
of zinc oxide in Waelz Kilns (one plant only), (3) operation of
retort and oxidizing furnaces, (4) leaching of high-cadmium dusts
in the cadmium plant.
As at Model 1 plants, both plants represented by this model
treat roaster off-gas in contact sulfuric acid plants to control
S02 emissions. The plants produce a salable acid and a bleed
stream (acid plant blowdown) that must be neutralized. One plant
neutralizes the blowdown with lime, which leads to generation of
an estimated 5,000 tons (4.5 Gg) per year of settled sludge
requiring disposal. An equal quantity of sludge is recycled to
the process. The waste generation factor for acid plant blowdown
at this plant is 0.042 ton per ton of zinc product.
The other pyrometallurgical plant uses the acid plant
blowdown to cool and humidify the roaster off-gas in a
humidifying scrubber. Acid plant blowdown from the scrubber is
thickened and then cooled before being recycled to the scrubber.
A bleed stream from the thickener bottoms is sent to the cadmium
5-32
-------
plant for cadmium recovery. This acid plant process generates no
solid wastes.
One of the two plants processes an oxide ore in Waelz kilns.
Because this ore cannot be concentrated, the Waelz kilns are used
to reduce the zinc oxide in the ore to zinc, vaporize the zinc,
and oxidize it back to zinc oxide, leaving the gangue material as
residue. This waste amounts to 204,000 tons (185 Gg) per year at
the model plant. The waste generation factor is 1.7 tons per ton
of zinc metal product.
The third source of waste, operation of retort and oxidizing
furnaces, produces a furnace residue, which is the gangue left
behind after the zinc oxide in the concentrates is reduced to
zinc and removed. This residue amounts to approximately 137,000
tons (124 Gg) per year from the model plant's retort furnaces and
approximately 44,000 tons (40 Gg) per year from its oxidizing
furnace. Such residues are a solid waste at only one of the two
plants represented by this model. At the other they constitute a
byproduct that is either recycled continuously or sold. The
generation factor calculated for retort furnace residue is 1.14
tons of residue per ton of zinc metal produced. An additional
solid waste generated by this process at both plants is scrap
furnace brick that is periodically discarded when the furnace is
rebuilt. Furnace rebuilding is usually done yearly. The
quantity of scrap brick discarded at the model plant is
approximately 4,500 tons (4.1 Gg) per year. The estimated
5-33
-------
generation factor for scrap furnace brick is then 0.038 ton per
ton of zinc metal produced.
Both of the plants represented by Model 2 process dusts with
high cadmium content that are collected from the sinter machine
off-gas in a cadmium plant. Processing in the cadmium plant
involves acid leaching, filtration, and cadmium precipitation to
produce a cadmium sponge. The leaching steps produce two
residues. One contains relatively large quantities of lead,
silver, and gold, and is sold as a byproduct. The other residue
constitutes a minor solid waste that is generated at a rate of
200 tons (181 Mg) per year at the model plant. The generation
factor is then approximately 0.002 ton per ton of zinc metal
produced.
With the waste generation factors developed herein and
values for production of the plants represented by this model,
one can calculate the quantities of solid waste currently
generated by the pyrometallurgical zinc plants (Table 5-4).
National Solid Waste Totals
The compilation of estimated and reported solid waste
quantities in this study indicates that the primary zinc industry
currently generates some 439,000 tons (398 Gg) of solid waste per
year (Table 5-5). The start up of a new electrolytic plant in
Tennessee could increase this total to about 467,800 tons (424
Gg) per year when this plant reaches its anticipated production
rate in 1979. Electrolytic plants, not including the new plant,
account for only 9 percent of the total solid waste generated
5-34
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TABLE 5-4
ANNUAL SOLID WASTE PRODUCTION AT PRIMARY ZINC PLANTS
REPRESENTED BY MODEL 2
Waste type
Waste
generation factor
(tons/ton of product)
Annual solid
waste production
(tons/year)
Adjusted annual
solid waste production
(tons/year)
Retort residue (vertical)
1.14
137,000
137,000
Retort residue
(electrothermic)
0.158
26,000
0
Oxide furnace residue
(traveling grate)
0.37
44,400
44,400
Oxide furnace residue
(electrothermic)
0.038
6,300
0
Waelz kiln residue
1.7
204,000
204,000
Acid plant blowdown
0.042
4,600
4,600
Scrap brick
0.038
8, 600
8,600
Cadmium plant residue
0.002
200
200
Total
431,200
398,800
Note: Metric conversion table is given in front matter.
-------
TABLE 5-5
1978 NATIONAL SOLID WASTE TOTALS FOR THE PRIMARY ZINC
SMELTING AND REFINING INDUSTRY
(tons/year)
Quantity generated at plants
represented by:
Waste type
Model 1
Model 2
Total
Anode slimes
2,600
2,600
"Geothite" residue
15,100
15,100
Acid plant blowdown
5,600
4,600
10,200
Dredge spoils
8,200
8,200
Waste water treatment sludge
8, 700
8,700
Retort residue
137,000
137,000
Oxide furnace residue
44,400
44,400
Waelz kiln residue
204,000
204,000
Scrap brick
8, 600
8, 600
Candmium plant residue
200
200
Total
40,200
398,800
439,000
Note: Metric conversion table is given in front matter.
5-36
-------
although they represent about 49 percent of the industry's
production of slab zinc. The two pyrometallurgical plants
account for 91 percent of the solid waste, although they
represent only 51 percent of the production of zinc. Furnace
residue from retort furnaces, oxide furnaces and Waelz kiln at
the pyrometallurgical plants account for about 88 percent of the
total solid waste produced by all plants. These are the three
major wastes (Table 5-5).
The six primary lead plants, operating in 1978, are located
in four EPA regions (Table 5-6). The new electrolytic plant is
located in EPA Region IV. Region III has two plants, both
pyrometallurgical. The majority, 91 percent, of the solid waste
generated by primary zinc production is located in Region III.
National Solid Waste Projections
Projected solid waste quantities are estimated by applying
current solid waste generation factors to the projected
marketable zinc production values for the years 1980, 1985, and
1990 (Table 5-7). These estimates are based on the following
assumptions:
1. All production increases will take place at
electrolytic plants.
2. Current solid waste generation factors as developed in
this study remain constant.
3. The quantity of solid waste produced as a result of air
and water pollution control will not change
substantially; therefore changes in projected solid
waste totals are essentially dependent on production
changes.
5-37
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TABLE 5-6
GEOGRAPHICAL DISTRIBUTION OF SOLID WASTE FROM THE
PRIMARY ZINC SMELTING AND REFINING INDUSTRY
(1978)
EPA Region
State
Number
of plants
Annual solid
waste production
(tons/year)
Annual regional
solid waste production
(tons/year)
III
Pennsylvania
2
398,800
398,800
V
Illinois
1
9,400
9,400
VI
Oklahoma
Texas
1
1
17,700
8,100
25,800
X
Idaho
1
5,000
5,000
National
total
6
439,000
439,000
Note: Metric conversion table is given in front matter.
-------
TABLE 5-7
PROJECTED SOLID WASTE FROM THE PRIMARY ZINC
SMELTING AND REFINING INDUSTRY
Projected solid waste
(tons/year)
Waste type
1980
1985
1990
Anode slimes
3,100
3,600
4, 300
"Goethite" residue
15,100
15,100
15,100
Acid plant blowdown
11,000
12,200
13,600
Dredge spoils
9,500
11,300
13,200
Waste water treatment
sludge
8,700
8,700
8,700
Retort residue
137,000
137,000
137,000
Oxide furnace residue
44,400
44,400
44,400
Waelz kiln residue
204,000
204,000
204,000
Scrap brick
8,600
8,600
8, 600
Cadmium plant residue
200
200
200
Total
441,600
445,100
449,100
Note: Metric conversion table is given in front matter.
5-39
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Although these assumptions are needed to make the projections,
their limitations must be noted. The quantity of solid waste
going to land disposal in the future as a result of existing and
pending air and water pollution control regulations will
increase; however it is extremely difficult to make a reasonable
estimate of these quantities because all air and water
regulations have not been promulgated, and the current standards
for air emissions and liquid effluents could be altered.
Additionally, the current compliance schedules could change, and
industry could implement any one of several mitigative approaches
to meet air and water regulations. The effect could be
profoundly different impacts on solid waste generation.
The assumption that all future production increases will
involve electrolytic plants is reasonable because of the
increasingly unfavorable environmental aspects of
pyrometallurgical plants coupled with their energy intensive
nature.
SCS engineers recently conducted a study that evaluates the
potential impacts of air and water quality regulations on land
disposal of solid wastes (5-16). The study addresses the Clean
Air Act of 1970 and amendments, and the Federal Water Pollution
Control Act of 1972 and its amendments. In an effort to
compensate for the numerous variables that will affect future
solid waste generation resulting from environmental regulations,
the researchers developed a minimum growth and a maximum growth
scenario (Table 5-8). Increases in solid waste generation due to
5-40
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TABLE 5-8
TOTAL ANNUAL SLUDGE FROM ZINC SMELTING AND REFINING
ATTRIBUTABLE TO AIR AND WATER REGULATIONS*
(1000 tons/year dry weight)
Historic
Minimum scenario^
Maximum
scenario
,+
Legislation
1967
1977
1980
1984
1987
1980
1984
1987
Water pollution
control act
35.6
16.8
26.1
32.2
36.8
26.1
32.2
36.8
Clean air act
186.4
127.9
326.2
957.1
278.7
226.3
268.1
306.0
Total
222.0
143.7
352.3
989.3
315.5
252.4
300.3
342.8
* SCS Engineers. Comprehensive Sludge Study relevent to section 8002(g) of
the Resource Conservation and Recovery Act of 1976 (PL 94-580) EPA. Contract No.
68-01-3945.
^ A brief explanation of the minimum and maximum scenarios is given in
Appendix B.
Note: Metric conversion table is given in front matter.
-------
production increases have not been factored out of these values.
It must be noted also that only a portion of these materials will
be disposed of on land and classed as solid waste; the remainder
will be recycled to recover metal contents.
Qualitative Characteristics of Solid Wastes
Of the four electrolytic plants operating through 1978 two
have wastewater treatment plants (WWTP) that generate a sludge
which require disposal. One of these plants uses a preleach
operation to process incoming concentrates that are high in
magnesium. This process generates a slurry that is treated in
the WWTP. Also sent to the WWTP at this plant are anode slimes
and acid plant blowdown. The sludge produced contains solids
precipitated and settled from these waste streams. The preleach
stream contains mainly MgS04, the anode sludge mainly Mn02 (50-55
percent) and some Pb (5-6 percent), acid plant blowdown varies
widely in composition but its precipitates usually contain Zn (to
25 percent), Ca0/CaS04 (20 percent) along with some Cd, Pb and
Se.
The other plant sends all plant runoff, acid plant blowdown,
sludge from deminerilization of process water, and plant wash
down to its WWTP. Sludge removed from this plant contains mud
and silt from runoff and washdown, precipitates (Zn, Ca0/CaS04,
Pb, Cd, Se) from acid plant blowdown, and salts and minerals from
the demineralization process. Anode slimes are not treated in
this WWTP and preleaching is not practiced. The sludge from both
WWTP plants is dewatered prior to disposal.
5-42
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Leach residue from electrolytic plants contains Pb, Cu, Cd,
Zn with small amounts of Ni, Co, Mg, As and Ag. This material is
reprocessed, usually at a lead smelter to recover the valuable
metals. Because of this, the leach residue is not a solid waste
but a byproduct. Another residue, goethite residue, is produced
by one electrolytic smelter in the processes of leaching and
purifying. The goethite residue is a solid waste that is
granular in structure. A typical analysis of goethite residue
is: Fe - 40 percent; Zn - 10 percent; S - 4 percent; Cu - 1.6
percent; Pb - 0.8 percent; Cd - 0.05 percent and Ag - 4 ounces
per ton (5-17). Goethite residue is removed from the operation
as a wet sludge that upon drying forms a surface crust. The
surface crust prevents wind erosion and fugitives, however,
destruction of the crust by truck traffic or other means can
allow the small granular particles to become airborne. Another
waste stream at the same plant that produces the goethite residue
is a sulfur residue. This sulfur residue is produced during
leaching and filtering and contains mainly sulfur and iron. Only
one plant produces these two solid wastes.
All primary zinc plants generate an acid plant blowdown
stream, in most cases this is a waste however it may be used or
treated in other processes to recover metal contents. Acid plant
blowdown varies in quantity and composition but typically
contains Zn, Cd, Pb, Se, and Ca0/CaS04 from neutralization.
Pyrometallurgical zinc plants produce a residue from the
operation of retort and oxidizing furnaces. One of the two
5-43
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operating pyrometallurgical plants also produces a residue from
the operation of a Waelz kiln. These three furnace residues
differ somewhat in their compositions (Table 5-9). Both verticle
retort and oxidizing furnace residue are black and have a
physical appearance similar to charcoal briquetes. Residue from
Waelz kilns is made up of gangue material present in the oxide
ore charge and appears rocklike and is usually in large chunks.
The final residue produced at pyrometallurgical plants is
generated in the cadmium extraction steps. This is a minor solid
waste in terms of quantities and represents a minor percent (less
than 0.1 percent) of the total solid waste produced at zinc
plants. Little information was available on its composition,
however, one study reported an analysis of cadmium plant residue
as: Pb - 8.9 percent; Zn - 3.9 percent; Cu - 0.2 percent; Cd -
0.14 percent (5-18).
In concurrence with the Federal Register of December 18,
1978 (43 Fed. Reg. 58946) the following solid wastes generated by
the primary zinc industry are considered hazardous in this study:
acid plant blowdown (SIC 3333); oxide furnace residue (SIC 3333);
anode sludge (SIC 3333); cadmium plant residues (SIC 3341)
(5-19). Those wastes reported in this study as being produced by
primary zinc plants and not included specifically in the
hazardous waste category as specified above are herein considered
to be nonhazardous solid waste.
5-44
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TABLE 5-9
TYPICAL ZINC FURNACE RESIDUE ANALYSIS*
(all values are percent by weight)
Furnace type
Parameter
Vertical retort
Oxide furnace
Waelz kiln
Zn
3.3
6.2
1.5
Fe
12. 7
6.6
19.7
Mn
0. 53
2.4
8.6
CaO
4.6
9.0
26.6
MgO
2.1
1.9
4.2
Si02
27.1
26.3
19. 9
AI2O3
11. 5
11.6
4.6
Na
0. 32
NA
NA
K
0.45
NA
0.29
Pb
0.34
NA
NA
S
NA
2.2
0.38
P
NA
NA
<0.1
SiC
0. 08
0.15
NA
C
27.3
26.4
6.8
Cd+
0
•
O
00
0.001
NA
Cr+
0. 005
0.002
NA
Cu+
0.46
0
•
0
CO
NA
Pb+
0.24
0.007
NA
* Data obtained during PEDCo site visit except as indicated.
+ Office of Solid Waste. Assessment of industrial hazardous
waste practices in the metal smelting and refining industry. 1977.
5-45
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Solid Waste Control Practices and Costs
This section describes practices for control of solid wastes
(hazardous and nonhazardous) generated by primary zinc plants,
and their associated costs. The first portion deals with current
control practices used by the zinc industry and the costs
attributable to the current practices. Next are presented
alternative control practices, which provide what are considered
to be adequate environmental safeguards and which satisfy the
RCRA Criteria. The costs attributable to this alternative system
are then estimated.
The alternative control systems specified in this study are
based on contractor investigations and on professional judgement;
they do not necessarily reflect EPA thinking or policy. The RCRA
Criteria for nonhazardous waste were used as guidelines in
developing the alternative systems, with consideration for both
technical and economic feasibility. The alternatives are not to
be considered as operational guidelines or standards that
industry should be required to follow; rather, they represent the
level of effort that could be required and the magnitude of cost
that could be incurred.
The costs presented for the current and alternative control
systems are estimates based on a control facility life of 20
years. The costs are those that would be incurred during the
life of the control facility. The cost of closure of existing
accumulated wastes is also estimated for the zinc smelting and
refining industry.
5-46
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The final portion of this section is an analysis of the
solid waste control costs. The analysis includes calculation of
the incremental cost that would be incurred by the zinc smelting
and refining industry through implementation of the alternative
control system and closure of existing waste facilities. The
portions of the incremental cost that are attributable to control
of nonhazardous and of hazardous solid wastes are designated;
then the fraction of the incremental cost for nonhazardous solid
waste control that can be attributed to the RCRA 4004
(nonhazardous waste) Criteria is determined on a state basis.
These additional costs attributable to RCRA for disposal of
nonhazardous wastes are compared with other industry costs
incurred in complying with current regulations for air and water
pollution control.
Current Solid Waste Control Practices
Current solid waste control practices are fairly uniform
throughout the zinc industry. Of the total solid waste generated
about 90 percent is controlled through on-site stockpiling, about
7 percent is removed by private and municipal organizations and
individuals for various uses such as winter road sand and the
remaining 3 percent is hauled and landfilled by private
contractors. The portion of solid waste from pyrometallurgical
plants controlled by onsite stockpiling is 92 percent, the
remaining 8 percent is the waste that is donated for other uses.
Thirty-one percent of the waste generated by electrolytic plants
5-47
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is hauled and landfilled by private contractors. This waste is
wastewater treatment plant sludge generated by two electrolytic
plants. The remainder of the wastes are stockpiled onsite.
Current control practice typically involves minimal effort
for stockpile site selection and preparation. Site selection is
based primarily on convenience or, at plants in urban areas with
limited property, on necessity. Site preparation consists
primarily of clearing and grubbing the solid waste stockpile
area. Four of the six primary zinc plants that use surface
impoundments have lined them with either clay or synthetic
material. Wells to monitor seepage or groundwater from disposal
sites are not adequately utilized at all plants and in most cases
not at all. Systems of drainage collection and diversion ditches
are not used to provide adequate protection at all plants,
however some plants have constructed a combination of diking,
ditching, and collection systems that are more than adequate to
control surface water runoff.
Current Control Practices at Electrolytic Plants—As
previously stated in the Sources, Quantities and Characteristics
section, electrolytic zinc plants produce solid waste consisting
of anode sludge, neutralized acid plant blowdown, surface
impoundment dredgings, wastewater treatment sludge and goethite
residue. Two of the electrolytic plants use wastewater treatment
plants (WWTP) to treat plant wastewater and various process
sludges. At both of these plants the WWTP sludge is removed and
hauled to offsite landfills. One plant removes this sludge
5-48
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continuously as it is filtered (dewatered). There is no onsite
storage or disposal. This particular sludge contains solids from
anode sludge, neutralization of acid plant blowdown, impoundment
dredgings and sludge generated from treatment of a preleach
slurry. The other plant using a WWTP temporarily piles WWTP
sludge onsite to dry prior to removal and haulage to an offsite
landfill. This particular sludge contains solids from
neutralization of acid plant blowdown and solids precipitated
from plant runoff and washdown. At this plant anode sludge is
not treated in the WWTP but is stockpiled onsite. WWTP sludge
amounts to about 31 percent of the solid waste generated at
electrolytic plants. All of this sludge is hauled to offsite
landfills either with or without temporary onsite storage.
The two remaining electrolytic plants stockpile their anode
sludge, neutralized acid plant blowdown, and dredgings from
surface impoundments onsite. One of these plants generates two
additional solid wastes that none of the other plants generate.
These two wastes, goethite and a sulfur residue, are stockpiled
onsite. Liners or seepage collection systems are not used in
current land disposal control practices of solid wastes.
Three of the four electrolytic zinc plants operating through
1978 use lined surface impoundments. Two of these plants utilize
synthetic liners while the other uses a clay liner. The fourth
plant has a surface impoundment, however it is unlined at this
time. Monitoring wells, although used by at least one plant, are
5-49
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not utilized to the extent that adequate monitoring of leachate
is provided.
The new plant that is expected to reach full production
levels in 1979 is assumed to have a WWTP and the sludge generated
removed to an offsite landfill. It is also assumed that this
plant uses a lined impoundment and treats anode sludge, acid
plant blowdown, impoundment dredgings and plant wastewater in the
WWTP. These assumptions, based on plant similarities as
indicated in the available literature, were made to estimate
potential solid waste generation at this new facility. In order
to avoid underestimation of the new plant is also assumed to
generate a solid waste, such as a goethite residue, that is
stockpiled onsite.
Current Control Practices at Pyrometallurgical Plants—As
previously stated in the Sources, Quantities and Characteristics
section, the two pyrometallurgical zinc plants produce furnace
(retort, oxide and Waelz kiln) residue, scrap furnace brick, and
a cadmium plant residue. As also previously stated one of these
plants has a relatively small solid waste stockpile because
furnace residue is removed from the site by various persons and
organizations for assorted uses as fast as it is produced. It is
also estimated that the remaining stockpiled residue will be
completely removed within a couple of years. The other
pyrometallurgical plant has an extremely large stockpile of solid
waste. This plant alone generates about 89 percent of the solid
5-50
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waste produced by all primary zinc plants. Solid waste stockpile
sites are located primarily due to convenience. Site preparation
other than clearing and grubbing is not conducted.
Both of these plants have surface impoundments. At one of
the plants the impoundment is lined with synthetic material, the
other plant's impoundment is not lined. These impoundments serve
to collect acid plant blowdown and plant water at one plant. The
other plant does not slurry the acid plant blowdown to the
impoundment but instead to the cadmium plant for further
processing. Dredgings from both impoundments are controlled
onsite. One plant recycles all dredgings to the process while
the other plant recycles about half of the dredgings and
stockpiles the remainder. Cadmium plant residue is also
stockpiled onsite at one plant.
Surface water control by collection and diversion ditching
is not used to its fullest potential at these plants. Likewise
barriers to prevent seepage from solid waste stockpiles or wells
to monitor or collect any seepage or leachate are not currently
used.
Cost of Current Controls
The costs of current solid waste control practices are
developed by use of model plants. The control methods considered
in the cost development represent those used most commonly in the
primary zinc industry. Details of unit costs and assumptions on
cost items are given in Appendix C. Control sites for
stockpiling solid waste are sized to provide 20 years of use at
5-51
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current waste generation rates. Capital cost for each model
include those for land, construction and equipment, plus a 10
percent contingency factor. Annual costs are calculated by
amortizing land and construction costs over a 20 year payout
period, equipment over a 10 year period, then adding operating
and maintenance cost including taxes and insurance.
Control costs are computed in 1978 dollars per ton of zinc
produced by dividing the capital and annual costs by the annual
slab zinc production at each model plant. The resulting cost
factors are extrapolated to that model plant category of the
industry and adjustments are made for plants that deviate from
the model scenario. The total costs to each model plant category
are summed to yield a total industry cost for current control of
solid wastes.
Current Control Costs for Model 1—Model 1 represents the
primary zinc plants that use electrolytic processes to produce
slab zinc. Solid wastes at these plants are anode sludge,
neutralized and plant blowdown, impoundment dredge spoils,
goethite residue and wastewater treatment plant sludges. Current
control costs are developed for all of these wastes. The
appropriate adjustments are made to accurately reflect the costs
attributable to the control of wastes such as goethite residue
and WWTP sludges that are not produced at all plants. The model
plant costs are those costs of controlling, handling and disposal
of solid wastes common to all plants, adjustments are made after
these costs are developed.
5-52
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A land area of 2 acres (0.8 ha) is designated for disposal
of anode sludge and surface impoundment dredgings, which include
neutralized acid plant blowdown. This land requirement is based
3
on an assumed anode sludge density of 125 pounds per ft (2,000
3 3
kg per m ) that would result in a waste volume of 214,400 ft
3
(6,100 m ) after 20 years of generation. The impoundment
dredgings estimated to be produced over the 20 year period amount
to about 1,775,900 ft^ (50,300 nf*) assuming a density of 47.3
3 3
pounds per ft (760 kg per m ) (5-18). From this it was assumed
3 acres (1.2 ha) would be a sufficient land area for disposal.
Costs for the current system include the surveying and
clearing and grubbing at the disposal area. The unit costs of
these activities are detailed in Appendix C. The disposal site
is assumed to be located 0.5 mile (0.8 km) from the plant. The
cost of a 0.5 mile (0.8 km) gravel haulage road, detailed in
Appendix C, is included in the current cost.
A land area of 4.4 acres (1.8 ha) is required for a surface
impoundment having a surface area of 2.8 acres (1.1 ha). This
surface impoundment receives acid plant blowdown and plant
washdown with some runoff. The cost of constructing the surface
impoundment, $14,700, is based on unit costs for excavation, dike
forming and grading as described in Appendix C.
The impoundment is lined with a synthetic liner that has an
18 inch (0.46 m) protective soil cover. The cost of liner and
5-53
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soil cover, $62,900 and $16,000 respectively are based on unit
costs of $4.16 per yd2 ($4.97 per m2) and $2.04 per yd^ ($2.67
3
m ) respectively.
The equipment requirements of this system include only a
dump truck and dredging system. Dredging of the impoundment is
done with a 2 HP pump and requires 178 hours per year. This
dredging activity removes about 2,100 tons (1.9 Mg) per year
3 3
which on a volume basis is approximately 3,290 yd (2,500 m ).
Installed cost of the pump and 1,500 feet (460 m) of piping is
$7,000. A dumptruck with a 20 ton (18 Mg) capacity is used to
transport anode sludge to the disposal site. It is assumed one
round trip from the plant to the disposal site takes one hour.
Equipment costs are calculated by applying usage factors to the
unit equipment capital cost. It is estimated that the dumptruck
will be involved in solid waste haulage 5 percent of the time.
The usage factor for the truck is then 5 percent and is applied
to a capital cost for the truck of $37,000 yielding an applied
capital cost of $1,900. The development of usage factors allows
an appropriate cost to be attributed to multiuse equipment. The
pump and piping system used to dredge the surface impoundment is
assumed to have a usage factor of 100 percent.
A 10 percent contingency factor is applied to all capital
cost. This contingency factor allows a margin of safety to be
calculated into the cost estimates.
Annual costs for land, construction, equipment, taxes and
insurance are calculated from the appropriate capital costs as
5-54
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detailed in Appendix C. Operation and maintenance costs are
based on the unit costs for personnel, fuel and electricity and
the percentages of capital cost for repair that are enumerated in
Appendix C. Personnel cost include a truck driver and foreman.
The truck driver is involved in solid waste haulage 100 hours per
year or about 5 percent of his time. Foreman's time is
calculated as being 20 percent of the driver's time. The model
plant capital and annual costs are $142,600 and $28,600
respectively (Table 5-10).
As previously mentioned one plant produces an additional
solid waste, goethite residue. Due to the generation and onsite
stockpiling of this waste the one plant that produces it will
have additional costs for: land, survey, site preparation,
equipment, personnel, maintenance and fuel. To make the
necessary adjustments on additional 5 acre (2.0 ha) land area
with appropriate survey and site preparation costs was added. In
addition equipment, fuel, and personnel costs calculated on the
basis of 750 hours per year were also added. The hours of
operation were calculated from the quantity of goethite residue
produced, 15,000 tons (13.6 Gg), divided by the hourly capacity
of haulage equipment, 20 ton (18 Mg) per hour. These additional
costs, $23,900 capital and $17,900 annual, were calculated on the
same basis as previously described and the unit costs as
presented in Appendix C.
Two of the electrolytic plants generate a WWTP sludge. This
sludge is hauled to an offsite landfill. For the purpose of
5-55
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TABLE 5-10
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 1: ELECTROLYTIC ZINC PLANTS
(1978 dollars)
Residue
disposal
Sludge
disposal
Capital Cost
Land
Construction
Survey
Site preparation
Haulage road
Surface impoundment
Liner
Seal protection
2, 900
1,100
600
15,600
4,300
1, 700
900
14,700
62,900
16,000
Equipment
1, 900
7,000
Subtotal
Contingency (10%)
22,100
2, 200
107,500
10,800
TOTAL CAPITAL COST
24 , 300
118,300
142,600
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and electricity
400
2, 200
300
1, 600
1, 000
200
600
12,300
1, 300
1, 800
5,200
50
Taxes
Insurance
100
200
100
1, 200
TOTAL ANNUAL COST
6,000
22,550
28,600
5-56
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this study it was assumed that the cost to the plant to have its
WWTP sludge hauled to the offsite landfill by private contractor
is $10 per ton ($9.1 per Mg). Information obtained during site
visits by the PEDCo project team indicate one of the plants
generates about 4,800 tons (4.4 Gg) per year sludge, 50 percent
solids, while the other produces about 17,500 tons (15.9 Gg)
sludge also containing 50 percent solids. This disposal cost is
then an additional $223,000.
The total capital and annual costs for the current solid
waste disposal system associated with the Model 1 plant are
$142,600 and $28,600 respectively (Table 5-10). The capital and
annual cost factors for Model 1 are $2.13 and $0.43 respectively
per ton of slab zinc produced. The total industry capital cost
for current solid waste disposal at the primary zinc plants
represented by Model 1 is $571,500, the total industry annual
cost is $115,400. The capital and annual costs with the
adjustments added as discussed are $595,400 and $356,300
respectively.
Current Control Costs for Model 2—Model 2 represents the
two primary zinc plants that use pyrometallurgical processes to
produce slab zinc. As discussed in the Sources, Quantities and
Characteristics section, solid waste at these plants include
neutralized acid plant blowdown, furnace (retort, oxide and Waelz
kiln) residues, and cadmium plant residue. As also discussed in
that section not all of these wastes are produced or are
stockpiled onsite at both of these plants. Current solid waste
5-57
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control costs are developed for all wastes that are stockpiled or
other wise controlled by the operator on a model plant basis.
The necessary cost adjustments are made after the model costs are
developed so that the cost reported reflects the most accurate
information available.
A land area of 70 acres (28 ha) is designated for disposal
of the furnace residues and the neutralized acid plant blowdown.
The estimated total volume of these wastes that are produced over
a 20 year period is 1.93 x 108 ft3 (5.5 x 106 m3). This volume
of waste can be stockpiled on a 70 acre (28 ha) site and have
sides with 3:1 slopes. The land area requirement is used to
calculate land, survey, and site preparation costs. These costs
are based on the unit costs presented in Appendix C.
The disposal site is assumed to be located 1.0 mile (1.6 km)
from the plant. The cost of a 1.0 mile (1.6 km) rail haulage
system, detailed in Appendix C, is included in the current
capital costs.
A land area of 1.9 acres (0.8 ha) is required for a
relatively small surface impoundment having a surface area of 1
acre (0.4 ha). The costs of land, survey and site preparation
are calculated as previously discussed. The cost of constructing
the surface impoundment, $9,300, is based on the unit costs for
excavation, dike forming and grading as detailed in Appendix C.
The impoundment is lined with a synthetic liner that has an 18
inch (0.46 m) protective soil cover. Unit cost are presented in
Appendix C.
5-58
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Equipment requirements and costs at the model plant include:
a yard engine, 6-100 ton (91 Mg) hopper cars, a bulldozer, a 2 HP
dredge pump and 1,500 ft (460 m) of piping - $7,000.
The yard engine and hopper cars are used to transport
furnace residue to the disposal site. It is assumed one round
trip from the plant to the disposal site takes one hour.
Equipment costs are calculated by applying usage factors to the
unit equipment costs. It is estimated that the rail equipment
will be involved in solid waste haulage 100 percent of its
available time and the bulldozer approximately 25 percent of the
time. The dredge pump and its associated piping are involved 100
percent of the time in solid waste handling. The development of
usage factors allows an appropriate cost to be attributed to
solid waste control practices for multiuse equipment.
A 10 percent contingency factor is applied to all capital
costs. This contingency factor allows a margin of safety to be
calculated into the cost estimates.
Annual costs are calculated as described for Model 1.
Annual hours of operation used in calculating annual costs are
rail system - 2,800 hours and dozing - 700 hours.
The model plant capital and annual costs are $536,600 and
$275,200 respectively (Table 5-11). The capital and annual cost
factors for Model 2 are $4.47 and $2.29 respectively per ton of
zinc produced.
As previously mentioned all of the furnace residue generated
at one of the pyrometallurgical plants is removed. It is
5-59
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TABLE 5-11
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR
MODEL 2: PYROMETALLURGICAL ZINC PLANTS
(1978 dollars)
Residue
disposal
Sludge
disposal
Capital Cost
Land
Construction
Survey
Site preparation
Haulage road
Surface impoundment
Liner
Seal protection
Rail line
68,000
26,200
14,000
15,600
206,000
1,800
700
400
9, 300
23,000
5, 900
Equipment
109,900
7, 000
Subtotal
Contingency (10%)
439,700
44,000
48,100
4,800
TOTAL CAPITAL COST
483,700
52,900
536,600
Annual Cost
Land
Construction
Equipment
Operation and maintenance
Personnel
Maintenance
Fuel and electricity
8,800
33,700
19,700
160,000
18,100
14,500
200
5,100
1, 300
4,300
2,300
50
Taxes
Insurance
1,700
4,800
50
600
TOTAL ANNUAL COST
261,300
13,900
275,200
5-60
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estimated that only 2 acres (0.8 ha) are required to provide
temporary storage for this waste until it is removed from the
site. The removal of this waste is carried out without any cost
to the operator. In order not to overstate costs an adjustment
is made for this smaller area and associated costs (land, survey,
site preparation and taxes). Waste handling costs and the cost
of the surface impoundment are unaffected by this adjustment.
An additional adjustment is made to accurately reflect that
only one plant has lined its impoundment. To make this
adjustment the costs (capital and associated annual) of a liner
and its protective soil cover are subtracted from the model
category capital and annual costs. The calculated total capital
and annual cost for current solid waste control at primary zinc
plants represented by Model 2 are $452,900 and $251,000
respectively. These costs include the adjustments to the model
plant cost approach as discussed. These cost indicate a capital
cost of $1.64 and an annual cost of 0.91 per ton of zinc produced
by pyrometallurgical plants.
Total Current Solid Waste Control Cost—The estimated total
primary zinc industry current capital and annual control costs
are $1,048,300 and $607,300 respectively (Table 5-12).
Pyrometallurgical plants account for 43 percent of the capital
cost and 41 percent of the annual cost, electrolytic plants
account for the remainder. Based on a total industry production
of 544,200 tons (494 Gg), the estimated current annual control
costs are $1.12 per ton ($1.23 per Mg) of slab zinc produced or
5-61
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TABLE 5-12
TOTAL COST OF CURRENT SOLID WASTE CONTROLS FOR THE PRIMARY
ZINC SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 595,400 356,300
Model 2 499,400 263,250
Total 1,094,800 619,550
5-62
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$0.00056 per pound ($0.00123 per kg) of zinc product. Based on a
total industry annual solid waste production of 439,000 tons (398
Gg) the current annual control cost is $1.38 per ton ($1.52 per
Mg) of waste produced.
Alternative Solid Waste Control Practices
This section proposes alternative methods of solid waste
disposal that are judged to provide sufficient environmental
safeguards. The disposal practices are designed to protect human
health and eliminate potential contamination of air and water.
These practices consist of relatively intensive site selection,
extensive site preparation, ground sealing, a seepage collection
system, runoff collection and diversion ditches, wells for
monitoring of groundwater, flood dikes, fencing, closure of
disposal sites, and postclosure monitoring and maintenance. Such
control practices are rarely followed in current disposal
operations at primary nonferrous metals plants. A detailed
site-specific analysis is needed to determine which controls are
appropriate at each site. For example, collection of seepage may
not be necessary where groundwater levels are low or where
natural soil formations limit the possibility that seepage will
reach groundwater. Important constituents of the alternate
control method that are common to all situations are relatively
intensive site selection, groundwater monitoring, site closure,
and postclosure monitoring and maintenance.
The site selection process involves the following
considerations: topography; soil type, including the chemistry
5-63
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and permeability of surface and underground soils; availability
of land for expansion; long-range land use; consideration of
environmentally sensitive areas; and aesthetics. A site
selection process of this scope will increase the disposal costs
but will minimize long-term adverse effects.
Groundwater monitoring in the alternative system is designed
to detect contamination resulting from solid waste disposal. The
system incorporates six monitoring wells within the plant
boundaries. At least one of these is to be installed
hydraulically upgrade from the disposal site to collect
background data on groundwater quality. Two wells are installed
immediately adjacent to and hydraulically downgrade of the
disposal site. Two of the remaining three wells are installed
within the property line hydraulically downgrade of the disposal
site. The sixth well can be situated wherever required (within
the plant line) to provide additional monitoring of groundwater.
Closure of a disposal site at the end of its useful life is
required under recently proposed (hazardous waste) regulations
and will probably be required for disposal of both hazardous and
nonhazardous solid wastes. Site closure consists of covering the
solid wastes with soil and revegetating the soil cover to prevent
erosion. The bottom cover layer is a soil having low
permeability to minimize water seepage into the waste; the upper
layer is topsoil capable of supporting indigenous vegetation. To
ensure that funds will be available at the time of site closure,
a trust fund is established before the site is opened.
5-64
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The proposed regulations also require postclosure monitoring
of groundwater and leachate and maintenance of the site for 20
years after closure. Monitoring of groundwater and leachate
involves periodic collection and analysis of samples from the
onsite wells and the seepage collection system. Postclosure site
maintenance consists primarily of maintaining the soil cover,
vegetation, monitoring wells, and security fencing. Again, a
trust fund to provide the required capital is established before
the site is used for waste disposal.
Alternative Control Practices at Electrolytic Plants--The
alternative control system designated for the Model 1 plant
includes all of the previously described practices in the current
system and the additional items described for the alternative
system. These additional items at the Model 1 plant include:
increased site selection efforts, an increased land area, drain
systems beneath both surface impoundments and solid waste
disposal areas, a soil-cement pad for solid waste disposal areas,
collection and diversion ditching around control sites, access
control (fencing), a flood control dike, monitoring wells,
sampling and analysis, and provisions for site closure and
postclosure maintenance.
The alternative system includes both a land disposal area
and surface impoundment, just as the current system, for control
of solid wastes. The land area devoted to each disposal site is
greater than the current system, however, to provide a buffer
5-65
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zone around the site that can accomodate the wells, fences, sumps
and pumps of the alternative system.
At both disposal sites drain systems are installed beneath
the actual disposal area to collect any leachate which may get
through the soil sealer. The drain system is designed to collect
the leachate and carry it to a common point from which the
leachate is pumped to treatment. This system consists of
perforated plastic piping. The seal beneath the land disposal
area consists of a 6-inch thick soil-cement pad. This pad is
intended to give structural support and minimize any seepage.
The pad is also graded so that runoff from this area can be
collected. The impoundment seal consists of a synthetic liner
covered with a layer of protective soil. This is the same as the
current surface impoundment controls. A drain system is also
located beneath the impoundment to collect any seepage or leaks
from a ruptured liner.
A system of drainage ditches is provided on the upgrade and
downgrade boundaries of the land disposal area. The upgrade
ditch is intended to divert surface runoff around the disposal
site and the downgrade ditch is intended to collect runoff from
the disposal site. A flood dike is provided around the land
disposal area also, to protect the area from inundation by
floodwaters. This dike is of the same dimensions as the
impoundment dike, thus the impoundment dike is assumed to provide
sufficient flood protection for the impoundment.
5-66
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Access control is also provided. A fence is installed that
surrounds the land disposal area and the surface impoundment. It
is assumed that these two areas are in close proximity.
Alternative Control Practices at Pyrometallurqical
Plants—The alternative control system designated for the Model 2
plant includes all of the previously described practices in the
current system and the additional items described for the
alternative system. These additional items at the Model 2 plant
are the same as described for Model 1.
Cost of Alternative Controls
The costs of the alternative solid waste controls for the
zinc industry are developed with the same model plant approach as
used for current costs. The capital costs for these controls
include costs for site selection, land, construction, equipment,
closure, and postclosure operations. These costs are presented
by control category, either land disposal or slurries disposal as
were current costs.
Some of the alternative control practices do not apply to
any specific waste or control category but to the entire control
facility. These practices are site selection, monitoring wells,
sampling and analysis of water samples, closure, postclosure
operations and fencing. The cost of site selection, monitor
wells and sampling and analysis are distributed equally between
the waste types. The costs of closure and postclosure practices
are distributed between wastes in proportion to waste quantities.
5-67
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Cost of fencing is distributed in proportion to area requirements
for each waste type. These cost distributions are applied to
both models.
To ensure that sufficient funds for closure will be
available at the end of the life of the control facility, the
alternative system specifies establishment of a trust fund when
the facility is opened. This fund, with accrued interest, will
cover the cost of closure. A trust fund is also established to
provide capital for postclosure operations. Details of these
trust funds appear in Appendix C.
Alternative Control Costs for Model 1—The alternative
control costs developed for Model 1 include all of the costs for
the items described as current controls plus the costs of the
additional items described for the alternative system. As are
current control costs, the alternative costs are developed on the
model plant basis (Table 5-13). The model plant costs are then
calculated on a cost per production basis so that the model costs
can be extrapolated to estimate industry cost. The appropriate
adjustments are again made as were in Model 1 current costs for
plants generating WWTP sludges and goethite residue.
Site selection is one of the most important aspects of the
alternative system. The cost of this activity is estimated to be
$59,800 per plant (Appendix C). This cost includes an engineers
time, a hydrogeological survey of three potential sites, and a
summary report upon which the site selection if based. This cost
5-68
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TABLE 5-13
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 1: ELECTROLYTIC ZINC PLANTS
(1978 dollars)
Land Sludge
disposal disposal
Capital Cost
Site selection
29,900
29,900
Land
3, 500
5,100
Construction
Survey
1,400
2,000
Site preparation
1, 900
2,800
Haulage road
15,600
Surface impoundment
14,700
Liner
62,900
Seal protection
16,000
Drain system
9,900
14,600
Concrete pad
24,700
Ditching
4 , 900
Flood dike
30,600
Fencing
11,300
25,100
Monitoring wells
8,250
8,250
Equipment
1,900
7,000
Closure operations
2, 900
9,100
Postclosure operations
56,600
177,500
Subtotal
203,350
360,550
Contingency (15%)
30,350
54,100
TOTAL CAPITAL COST
233,850
414,650
Annual Cost
Site selection
4,000
4, 000
Land
500
700
Construction
14,600
19,700
Equipment
400
1, 300
Operation and maintenance
Personnel
1,600
1,800
Maintenance
5, 000
7,700
Fuel and electricity
200
60
Sampling and analysis
10,000
10,000
Closure operations
400
1,200
Postclosure operations
7,600
23,900
Taxes
100
100
Insurance
2, 200
4,100
TOTAL ANNUAL COST
46,600
74,560
5-69
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is annualized over a 20-year period and distributed equally
between waste types.
The land requirement for alternative control is assumed to
be 20 percent greater than that required for current practice.
This additional area is needed for the placement of devices such
as diversion and collection ditches, monitor wells, fencing, and
sumps and pumps. Unit land cost and amortization are the same as
for current controls.
In addition to construction costs detailed for the current
system, the alternative system includes costs for added site
preparation, drain systems, a soil-cement pad, ditching, flood
dike, fencing and monitoring wells. Site preparation includes
not only clearing and grubbing but also topsoil removal and
grading at a unit cost of $530 per acre ($1300 per ha). A drain
system consisting of parallel lengths of perforated plastic pipe
placed at 50 foot (15 m) intervals and connected to a sump and
pump by a transverse collection pipe is placed beneath both land
disposal and surface impoundment areas. This system detects and
collects any seepage (Details in Appendix C). Also constructed
on the land disposal area of 3.6 acre (1.46 ha) is a 6-inch thick
2 2
soil-cement pad at a cost of $1.70 per yd ($2.03 per m )
installed. The pad provides support, minimizes seepage and is
sloped toward the sump so that runoff can be effectively handled.
Ditching, upgrade diversion and downgrade collection
ditches, are installed on the land disposal area perimeter. The
5-70
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total length of ditching equals three times the length of one of
the sites sides or about 1100 feet (335 m). The installed cost
of ditching at the model plant is $4,900. Security fencing is
provided. The fence surrounds both the land disposal area and
the surface impoundment. This amounts to about 3640 feet (1110
m) at the model plant. Unit fencing cost if $10 per linear foot
($32.80 per m) installed.
To protect the land disposal area from inundation by flood
waters a flood protection dike is constructed around the area.
This dike, as detailed in Appendix C, is of the same dimensions
as the impoundment dike. It is estimated the construction of the
flood dike at the model plant will cost $30,600. This cost
induces all construction costs (survey, site prep, excavation,
forming, compaction, and grading) plus land cost and the cost of
vegetating the dike surface. It is assumed that 50 percent of
the primary zinc plants are located in flood plains and require
flood protection diking. The appropriate cost adjustment is made
in calculating industry costs to account for the fact that the
model plant has a flood dike but only 50 percent of the plants
require them.
A system of six monitoring wells is installed to monitor
groundwater at the model plant. The capital cost for this system
is $16,500. This system includes 6-100 feet deep wells
strategically placed within the plant boundary as described in
Appendix C.
5-71
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The capital cost for establishing a trust fund to provide
for closure at the end of the 20-year life of the control
facility of the model plant is estimated to be $12,000. Closure
includes covering the waste with 2 feet (0.61 m) of soil and
vegetating as described in Appendix C. The cost was calculated
on the assumption that a trust fund is established as previously
discussed. The establishment of a trust fund for postclosure
operations, 20-year monitoring and site maintenance, is estimated
to cost $234,100.
A 15 percent contingency factor is added to the capital
costs to provide a safety factor in estimating these costs.
The annual cost of site selection, land and construction are
calculated by amortizing the capital costs over a 20-year period
at 10 percent interest. Annual equipment operation and
maintenance, taxes and insurance costs are calculated as
described for current costs.
The model 1 alternative capital and annual costs are
$648,500 and $121,160 respectively (Table 5-13). The capital and
annual cost factors are $9.68 and $1.81 respectively per ton of
zinc produced.
Alternative Control Costs for Model 2—The costs developed
for the alternative control system of the Model 2 plant include
all of the costs for the items described in current controls plus
the costs of the additional items previously described for the
alternative system. As are current control costs, the
5-72
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alternative costs are developed and presented on the model plant
basis (Table 5-14).
Costs for site selection and monitoring wells are the same
as described for Model 1. The land area required for land
disposal is likewise increased 20 percent from 70 to 84 acres
(28.3 to 34 ha), over that required for the current system. The
added land allows for the additional area requirements for
ditching, placement of sumps and pumps, monitoring wells and
fences. The unit land cost is the same.
The design and unit cost of the drain systems, soil-cement
pad, ditching, flood dike, and fencing are the same as described
for Model 1 the only difference being their size. These costs
are considerably higher for the Model 2 plant because of the
greater quantity of waste generated and the larger land area
required than for the Model 1 plant. As with Model 1 it is
assumed that 50 percent of the Model 2 primary zinc plants are
located in flood plains and require flood protection diking. The
appropriate cost adjustment is made in calculating industry costs
to account for this.
The Model 2 alternative capital and annual costs are
$2,213,300 and $526,400 respectively (Table 5-14). The capital
and annual cost factors are $18.44 and $4.39 respectively per ton
of zinc produced.
Total Cost of Alternative Controls—The total costs
estimated for alternative controls in the zinc industry are
$4,782,850 capital and $1,241,260 annual (Table 5-15). With an
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TABLE 5-14
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR
MODEL 2: PYROMETALLURGICAL PLANTS
(1978 dollars)
Land
disposal
Sludge
disposal
Capital Cost
Site selection
29,900
29,900
Land
81,600
2, 200
Construction
Survey
31,500
900
Site preparation
44,500
1,200
Haulage road
15,600
Surface impoundment
9, 300
Liner
23,000
Seal protection
5, 900
Rail line
206,000
Drain system
136,000
5,500
Soil-cement pad
57,600
Ditching
23,700
Flood dike
133,600
Fencing
84,100
2,300
Monitoring wells
8,250
8, 250
Equipment
109,900
7,000
Closure operations
512,000
6, 600
Postclosure operations
343,900
4,400
Subtotal
1,818,150
106,450
Contingency (15%)
272,700
16,000
TOTAL CAPITAL COST
2,090,850
122,450
Annual Cost
Site selection
4,000
4,000
Land
11,000
300
Construction
99,700
7,600
Equipment
20,600
1,300
Operation and maintenance
Personnel
160,000
4,300
Maintenance
33,100
2,800
Fuel and electricity
16,700
60
Sampling and analysis
10,000
10,000
Closure operations
68,900
900
Postclosure operations
46,300
600
Taxes
2,000
100
Insurance
20,900
1,200
TOTAL ANNUAL COST
493,200
33,160
2,213,300
526,360
5-74
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TABLE 5-15
TOTAL COST OF ALTERNATIVE SOLID WASTE CONTROLS FOR THE
PRIMARY ZINC SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 3,004,400 780,000
Model 2 1,778,450 461,260
Total 4,782,850 1,241,260
5-75
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annual industry production of 544,200 tons (494 Gg), the annual
cost of the alternative system is approximately $0.0011 per pound
($0,025 per kg) of slab zinc. With annual solid waste generation
of 439,000 tons (398 Gg), the annual cost of the alternative
system is approximately $2.83 per ton ($3.12 per Mg) of solid
waste.
Cost of Closing Existing Solid Waste Control Sites
All zinc plants except one currently have onsite areas for
solid waste disposal. These disposal sites contain some or all
of the solid wastes described earlier, depending on the process
employed. The current and past practices for solid waste control
at these disposal sites may not provide adequate protection of
human health and the environment according to RCRA standards;
therefore, these sites may be declared open dumps, and operators
will be required to close or upgrade them.
For this study it is assumed that all existing onsite
disposal areas fail to meet RCRA criteria, that these sites will
be closed rather than upgraded to meet RCRA requirements, and
that new onsite disposal facilities that comply with RCRA
standards will be constructed. The costs of closure for existing
sites are estimated to determine the potential capital and annual
cost that may eventually be incurred by the zinc industry.
To estimate the order of magnitude cost of closure, one must
estimate the quantity of waste that has accumulated at the site.
This also was done on the model plant basis. To estimate this
cost at plants represented by the Model 1 category the quantity
5-76
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of waste present at the model plant is first calculated. The
model plant is assumed to have been operating for 31 years, an
average age of the plants represented, at 50 percent of current
capacity. It is also assumed this plant has been generating the
solid wastes identified earlier at the current generation rates.
Based on these assumptions it is calculated that the model plant
has approximately 3 acres (1.2 ha) of solid waste piled 15 feet
(4.6 m) high. Closure costs were calculated on the basis of and
with the unit costs presented in Appendix C. This closure cost
was then adjusted for each of the four plants represented by
adjusting it to account for individual plant production and years
of operation. The total costs of closure of existing sites for
Model 1 are $173,400 capital and $20,300 annual.
One of the plants represented by Model 2 has no waste
accumulation to be closed, the other plant has an extremely large
waste stockpile. The costs of closing existing waste sites at
Model 2 plants then is the cost for closing this one facility.
To estimate this cost, the surface area of the waste was
estimated. This estimate of size is based on first hand
information obtained during a site visit. This waste pile is
about 2.4 miles (3.8 km) in length, about 0.25 mile (0.40 km)
wide on average and about 60 feet (18 m) high. The pile is
situated against a hill so closure costs were only applied to the
exposed face. The surface area was estimated to be 384 acres
(155 ha) and total closure costs estimated to be $4,734,200 for
this one facility (Table 5-16).
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TABLE 5-16
TOTAL COST OF CLOSING EXISTING SOLID WASTE DISPOSAL SITES
FOR THE PRIMARY ZINC SMELTING INDUSTRY
(1978 dollars)
Plants represented by: Capital Annual
Model 1 173,400 20,300
Model 2 4,734,200 553,900
Total 4,906,600 574,200
5-78
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The total capital cost for closure of existing solid waste
facilities is estimated to be $4,907,600, and the total annual
cost, $574,200. The majority of this cost, 96 percent, is
attributable to one pyrometallurgical plant.
Analysis of Solid Waste Control Costs
The cost analysis includes calculation of the total
incremental cost of solid waste control that would be incurred by
the primary zinc industry in implementing the alternative
controls and closing existing disposal sites (Table 5-17). This
total incremental cost is presented on a basis of nonhazardous
and hazardous wastes. In this report acid plant blowdown, anode
sludge, cadmium plant residues and oxide furnace residue are
considered hazardous, the remaining wastes then are nonhazardous.
The total incremental annual cost for control of nonhazardous
solid wastes is $716,950; this represents about 60 percent of the
total incremental cost of controlling both classes of wastes
(Table 5-17).
The fraction of the incremental cost of controlling
nonhazardous solid waste that can be attributed to the RCRA
Criteria is estimated by grouping the incremental costs into two
categories: state-standard-induced (cost of complying with
existing state regulations) and Criteria-induced (cost of
complying with RCRA Criteria that are more stringent than state
standards). The Criteria-induced costs represent those
incremental solid waste control costs that cannot be attributed
5-79
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TABLE 5-17
CURRENT, ALTERNATIVE, CLOSURE, AND INCREMENTAL CONTROL COSTS
FOR THE PRIMARY ZINC SMELTING INDUSTRY
(1978 dollars)
Current Alternative"1" Closure5 Incremental'
Waste type* Capital Annual Capital Annual Capital Annual Capital Annual
Nonhazardous 376,900 276,350 1,907,850 507,000 4,156,600 486,300 5,687,500 716,950
Hazardous 717,900 343,200 2,875,000 734,360 751, 000 87,900 2,908, 100 479,060
Total 1,094,800 619,550 4,782,850 1,241,360 4,907,600 574,200 8,595,650 1,196,010
* Classification of solid waste as hazardous or nonhazardous is based on EPA's listing of
hazardous waste in the December 18, 1978, Federal Register (43 Fed. Reg. 58946).
+ Alternative control costs include the cost of the alternative controls together with the cost
of closing and maintaining the alternative disposal sites.
5 Closure costs represent the cost of closing existing solid waste disposal sites.
" Incremental costs equal the sum of the cost of alternative controls and cost of closure minus
the costs of current controls.
-------
to current state regulations. Provisions of state regulations
were determined by consulting an analysis of state regulations
and the proposed Federal Criteria (5-16).
The major costs to the zinc industry that could potentially
be attributable to the RCRA Criteria would derive from four
criteria, those dealing with environmentally sensitive areas
(flood plains), surface water, groundwater and safety (access).
Costs entailed in closure and postclosure maintenance of both
existing and alternative control facilities are also attributed
to RCRA. These costs cannot be directly attributed to any one
criterion but are indirectly attributable to all. For purposes
of this study all closure costs for nonhazardous wastes were
assumed to be attributable to the Criteria since existing state
regulations do not contain closure and postclosure requirements.
Other criteria, those dealing with wetlands, permafrost, critical
habitat, sole-source aquifers air, disease vectors explosive
gases, fires, toxic gases, bird hazards are considered
inapplicable to the domestic primary zinc industry.
All states with zinc plants have regulations covering
surface water, and access. Three states with zinc plants, Idaho,
Illinois and Oklahoma, do not have regulations covering
floodplains. One state, Oklahoma, does not have regulations
covering groundwater. All other states with zinc plants cover
these criteria. The Criteria-induced costs consist of those
costs attributable to closure of nonhazardous existing solid
waste facilities, closure and postclosure maintenance of
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nonhazardous alternative disposal facilities, the cost of flood
plain protection in three of the five states having zinc plants,
and groundwater protection in one state having one plant.
The RCRA-induced incremental annual cost for control of
nonhazardous wastes is $575,400; this represents 80 percent of
the total incremental annual cost of nonhazardous solid waste
control (Table 5-18 and 5-17).
For the purpose of comparison, the capital cost required to
bring the lead/zinc industry into full compliance with air and
water pollution control regulations is $149 per ton ($135 per Mg)
of production, of which $123 (83 percent) is for air and $26 (17
percent) is for water (5-20). The Criteria-induced incremental
capital cost developed in this study (Table 5-18) amounts to
approximately $9.41 per annual ton ($10.37 per Mg) of refined
lead product.* For reference, the average capital cost per
annual ton for a mine-mill-smelter in the copper, lead, and zinc
industries is estimated at about $1,500 (1975 constant dollars)
and the U.S. production costs for a hypothetical electrolytic
zinc plant with a capacity of 120,000 tons (109 Gg) per year were
estimated at $115 per ton ($127 per Mg) of slab zinc.
* Based on an annual zinc production of 544,200 tons per
year (Table 5-1).
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TABLE 5-18
CRITERIA-INDUCED CONTROL COSTS FOR THE PRIMARY ZINC
SMELTING INDUSTRY*
(1978 dollars)
State
Capital
Annual
Idaho
Illinois
Oklahoma
Pennsylvania
Texas
'Total
0
0
106,000
5,012,500
0
5,118,500
0
0
13,900
561,500
0
575,400
* These values include additional costs for closure
of accumulated nonhazardous solid waste, closure and post-
closure maintenance of alternative nonhazardous solid waste
systems, and Criteria-induced costs for states whose solid
waste regulations do not satisfy the Criteria.
5-83
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REFERENCES FOR SECTION 5
5-1. Cammarota, V.A. Mineral Commodity Profile - 12. Zinc.
U.S. Department of the Interior, Bureau of Mines,
Washington, D.C. May 1978.
5-2. Mineral Industry Surveys. Zinc Industry in June 1978.
U.S. Department of the Interior, Bureau of Mines,
Washington, D.C. September 6, 1978.
5-3. Personal Communication, Mr. V.A. Cammarota, Jr., Bureau of
Mines to M. Taft, PEDCo. September 25, 1978, September
29, 1978, and October 6, 1978.
5-4. Deane, G.L., et al. Cadmium: Control strategy analysis.
GCA Corporation Report No. GCA-TR-75-36-6. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. April 1976. p. 157.
5-5. Mineral commodity summaries 1978. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C. 1978.
5-6. Battelle Columbus Laboratories, Columbus, Ohio - Energy use
patterns in metallurgical and nonmetallic mineral
processing (phase 4 - energy data flowsheets,
high-priority commodities). U.S. Department of the
Interior, Bureau of Mines, Washington, D.C. Open File
Report 80-75. 1975. 192 pp.
5-7. Institute of Gas Technology. Study of industrial uses of
energy relative to environmental effects. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, July 1974.
5-8. Unalloyed, unwrought zinc. Office of the Secretary, U.S.
International Trade Commission, Washington, D.C.
5-9. Personal communication, Mr. S. Strauss, to M. Taft, PEDCo.
October 13, 1978.
5-10. Charles River Associates Incorporated, Boston, Masschausetts.
Lead, Copper, and Zinc price forecasts to 1985. Volume I
and II. CRA #410. U.S. Environmental Protection Agency,
Washington, D.C. August 1978.
5-84
-------
5-11. St. Joe studies construction of a zinc refinery.
Engineering and Mining Journal. 179(10). October 1978.
5-12. Mudry, M.L., Jr. Zinc-copper resources of Wisconsin.
Skillings Mining Review. 67(12 ):15-19,28. March 1978.
5-13. Schlecten, A.w. and A.P. Thompson. Zinc and zinc alloys.
In. Kirk-Othmer Encyclopedia of Chemical Technology,
2nd edition. V. 22. 1970.
5-14. PEDCo Environmental, Inc. Environmental assessment of the
domestic primary copper, lead, and zinc industries. U.S.
Environmental Protection Agency. Contract No. 68-03-0537.
September 1978.
5-15. U.S. Environmental Protection Agency. Development document
for the interim final effluent limitations guidelines and
proposed new performance standards for the zinc segment of
the nonferrous metals manufacturing point source category.
EPA-440/1-75/032. Washington, U.S. Government Printing
Office, February 1975. 155 p.
5-16. Office of Solid Waste. Comprehensive sludge study relevant
to Section 8002 (g) of the Resource Conservation and
Recovery Act of 1976 (PL 94-580). V.l. Environmental
Protection Contract No. 68-02-3945. Washington.
5-17. Personal communication and site visits. PEDCo project team
with primary zinc plant personnel. October 2-4, 1978.
5-18. Office of Solid Waste. Assessment of Industrial Hazardous
Waste Practices in the Metal Smelting and Refining
Industry. V.2. EPA Publication SW-145.C.1. National
Technical Information Service. Springfield, Virginia.
1977.
5-19. Federal Register. Hazardous Waste. Proposed guidelines and
regulations and proposal on identification and listing.
V.43. No. 243. p. 58946. Washington. U.S. Government
Printing Office, December 18, 1978.
5-20. MacDonald, B.I., and M. Weiss. Impact of environmental
control expenditures on copper, lead and zinc procedures.
Mining Congress Journal, 64(l):45-50, January 1978.
5-85
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SECTION 6
MINOR PRIMARY AND SECONDARY NONFERROUS
SMELTING AND REFINING INDUSTRIES
The minor primary and secondary nonferrous metals industries
that produce significant quantities of solid wastes include
primary smelting and refining of tin, antimony, mercury, and
titanium, and secondary smelting and refining of copper, lead,
and aluminum. Secondary zinc smelting is not considered in this
group because it generates very small amounts of land-disposed
wastes. Particulate matter collected from air pollution control
devices at secondary zinc smelters is not discarded; rather,
because it contains large amounts of zinc, it is used in
production of zinc chemicals, principally zinc oxide.
The remaining primary industries are small in comparison to
those already mentioned. Many of these industries (producing
cadmium, arsenic, selenium and tellurium, gold and silver,
platinum, and bismuth) process the residuals, slimes, dusts, and
sludges from the primary copper, zinc, or lead industries to
recover minor metals. Recovery is done either at the primary
smelters or at specialty smelters that process only electrolytic
slimes, dusts, or other residues (6-1).
6-1
-------
Secondary metals include all metals and metal alloys
recovered from scrap and waste. The chemical composition of
final products is specified according to the requirements of an
individual materials application. The quality of individual
alloy products is indistinguishable from that of materials of
comparable grade made by primary producers. To meet chemical
a
specifications the secondary smelters often add primary metals
for dilution or alloying purposes. Conversely, much of the waste
generated at a secondary smelter contains metal values exceeding
those in the corresponding ore concentrates and thus constitutes
a source of raw materials for primary smelting (6-1).
The only secondary smelting and refining industries of
appreciable production capacity are those processing copper,
lead, zinc, and aluminum. Annual production of these industries
ranges from approximately 384,000 tons (348 Gg) of secondary
copper to approximately 1,430,000 tons (1.30 Tg) of secondary
aluminum. Whereas the larger industries emphasized in this study
typically operate a small number of large-capacity plants located
in sparsely populated areas near mine-mill complexes, the
secondary nonferrous metals industries operate relatively large
numbers of plants in urban areas where the scrap used as raw
material is readily available.
Solid Waste Characterization
This section characterizes the four minor primary and three
secondary nonferrous smelting industries that produce solid
6-2
-------
wastes in significant quantities. Delineation of potentially
hazardous and nonhazardous wastes generated by these industries
is based on EPA's listing of hazardous wastes in the December 18,
1978 Federal Register. Solid waste generation factors have been
developed (Table 6-1) that relate solid waste quantities to metal
production. The factors were used to estimate the quantities of
solid waste components from each of these industries (Table 6-2).
It is estimated that the solid wastes from 2,600,000 tons (2.3
Tg) of metal produced by these industries in 1977 totalled
1,157,200 tons (1.05 Tg), of which 524,000 tons (475 Gg), or 49.6
percent, is considered nonhazardous.
Primary Tin
The only primary tin smelter in the United States is a plant
of the Gulf Chemical & Metallurgical Company in Texas City,
Texas. Marketable byproducts of the plant are cathode melting
dross, lead-tin alloy solder, copper-silver cement, and ferric
chloride solution.
The major process sequence in production of tin ingot
include the following operations:
1. Roasting of concentrate in a multiple hearth furnace to
drive off sulfur dioxide and produce an oxidized
concentrate.
2. Acid leaching of roasted concentrate to remove iron,
copper, silver, and other metallic impurities.
3. Two stage smelting to produce 95 percent pure tin
bullion and a slag byproduct.
4. Electrolytic refining of 95 percent tin bullion to
produce 99.9 percent pure tin.
6-3
-------
TABLE 6-1
WASTE GENERATION FACTORS FOR MINOR PRIMARY AND SECONDARY
NONFERROUS METALS INDUSTRIES
Solid waste Hazard rating*
generation factor* Potentially
Industry Type of solid waste (lb/ton of product) hazardous Nonhazardous
Primary tin
Smelting slag
1,830
X
Primary antimony
Blast furnace slag
5,600
X
Electrolytic sludge
420
X
Primary mercury
Kiln or retort residue
414,000
X
Primary titanium
Chlorination sludge
660
X
Secondary copper
Blast furnace slag
700
X
Electrolytic wastewater
sludge
0.8
X
Secondary lead
Blast furnace slag
900
X
Cupola furnace slag/matte
450
X
Reverberatory furnace slag
332
X
Scrubber sludge
44 (dry wt.)
X
Secondary aluminum
High salt slag
2,800
X
Scrubber sludge
150
X
* Separation of solid waste into hazardous and nonhazardous components is based on EPA's listing of
hazardous wastes in the December 18, 1978 Federal Register (43 Fed. Reg. 58946).
t Calspan Corporation. Assessment of industrial hazardous waste practices in the metal smelting and
refining industry. Solid Waste Management Series Publication SW-145 c.2, Volumes 1 and 2. Environmental
Protection Agency, Solid Waste Management Division, Washington. 1977.
Note: Metric conversion table is given in front matter.
-------
TABLE 6-2
ANNUAL METAL PRODUCTION AND SOLID WASTE GENERATION BY MINOR
PRIMARY AND SECONDARY NONFERROUS METALS INDUSTRIES
(values as of 1977)
Solid waste generated'1' (tons/year)
Number
Production
Potentially hazardous
,5
Nonhazardous5
Industry
of plants*
(tons/year)*
Total
Total
Component
Quantity
Total
Component
Quantity
Primary tin
1
7,370
6,820
6.820
Smelting slag
6,820
Primary antimony
2
4,070
11,700
11.700
Blast furnace slag
Electrolytic sludge
11,450
250
Primary mercury
1
1,060
220,000
220.000
Kiln/retort
residue
220,000
Primary titanium
3
16.50011
5,600
5,600
Chlorlnatlon sludge
5,600
Secondary copper
460
384,000
196,000
196,000
Blast furnace slag
Electrolytic waste
water sludge
195,920
80
Secondary lead
1200
756,000
192,000
3,000
Scrubber sludge
3,000
189.000
Blast, cupola and
reverb, furnace slag
189,000
Secondary aluminum
100»
1,430,000
525,000
372,000
High salt slag
372.000
153.000
Scrubber sludge
153,000
Total
273
2,599,000
1,157,130
582,700
574,420
* U.S. Bureau of Mines. Minerals yearbook, 1975 ed., Washington, U.S. Government Printing Office. 1975, except as noted.
U.S. Bureau of Mines Mineral comnodity sumnarles 1979. Washington, U S. Department of the Interior, 1979, except as noted,
t Based on waste generation factors from Table 6-1.
§ Separation of the solid waste into hazardous and nonhazardous components is based on EPA's listing of hazardous wastes in
the December 18, 1978, Federal Register (43 Fed Reg 58946)
1 Based on total U.S production capacity. Actual production data withheld to protect company confidential data.
P Personal communication. Selected personnel of the Division of Ferrous Metals, U S. Bureau of Mines, Washington, DC., to
R S Amick, PEDCo Environmental, Inc., February 1979.
Note Metric conversion table is given in front matter
-------
Leaching is normally done with hydrochloric acid to remove
iron, copper, silver, and other metallic impurities. Leach
solution is treated by thickening and cementation to produce a
copper/silver cement product and a ferric chloride solution
(6-1).
In the two-stage smelting operation, coal is used as a
reductant. Dusts are removed from the flue gases and returned to
the smelting circuit. Iron and tin alloys are treated by acid
leaching to produce tin oxide and additional ferric chloride
solution for sale. Tin metal is routed to electrolytic cells for
further purification (6-1).
In electrolytic refining the crude tin from the smelter is
placed in sulfuric acid solution to produce pure tin cathodes,
which are subsequently melted and cast into ingots. Drosses from
the melting operation are either sold for recovery or returned to
the process stream. Anode slimes from the electrolytic circuit
are treated separately to produce a lead/tin alloy.
Much of the residue from leaching and electrolytic refining
is further processed for recovery of copper, silver, lead, and
other byproducts. Residuals of no value and small amounts of
nonrecoverable metallics are discarded with slag.
The smelting slag is designated as nonhazardous in this
study (Tables 6-1 and 6-2), on the basis of the proposed RCRA
classifications. The current method of slag disposal is believed
to be open dumping. Dusts collected from air pollution control
devices are recycled to the process (6-1).
6-6
-------
Primary Antimony
The primary antimony industry is relatively small (Table
6-2), with only two U.S. producers active in 1977 (6-2). Some
antimony is recovered as a byproduct at three primary lead
smelters. Over 90 percent of the byproduct antimony produced at
primary lead smelters was consumed at the smelter in
manufacturing antimonial lead.
Antimony metal may be produced by pyrometallurgical and
electrolytic processes. In the pyrometallurgical process, the
charge to the blast furnace consists of mixed oxide and sulfide
ores from mines in Mexico or the United States together with
byproducts of other smelting operations: mattes, slags, flue
dusts, or residues from lead and zinc refineries. The
blast-furnace process is somewhat similar to that in production
of lead. The process can produce extremely pure metal with
minimal antimony loss.
The only waste produced in the pyrometallurgical process is
a hard, siliceous blast-furnace slag produced at a rate of 2.8
tons per ton of antimony metal. All other byproducts are
recycled to the blast furnace. In current practice the slags
from reverberatory and/or blast furnaces are discharged to an
open dump onsite.
Electrolytic production of primary antimony metal is by a
leaching-electrolysis process. In this process, a complex
copper-antimony sulfide concentrate is leached with sodium
sulfide solution, which dissolves the antimony as sodium
6-7
-------
thioantimonate. The leach solution is clarified by settling and
filtration, and is electrolyzed in diaphragm cells to yield
antimony that is 93 to 99 percent pure.
The only waste from electrolytic production of antimony is
spent anolyte solution, which is discharged to a tailings pond
that also receives wastes from the mining and milling operations
(6-1).
Both the blast-furnace slag and the electrolysis sludge are
considered potentially hazardous in this study (Tables 6-1 and
6-2), in line with the proposed RCRA designations.
Primary Mercury
The primary mercury smelting and refining industry has been
centered in California, Nevada, and Oregon. Mercury has also
been recovered from ore in Arizona, Alaska, Idaho, Texas, and
Washington and is recovered as a byproduct from gold ore in
Nevada and zinc ore in New York. Production of mercury has
fluctuated considerably over the past decade. From 1974 to 1977,
production of primary mercury increased approximately
thirteen-fold, while in this same period the number of
primary-mercury-producing facilities declined from five
nationwide to one operation in Nevada.
Mercury is extracted from ore and concentrate by heating in
retorts or furnaces to liberate the metal as a vapor. The vapor
is then cooled, and the condensed mercury is collected. Recovery
of mercury is high, averaging about 98 percent at retort
installations and 95 percent at furnace plants.
6-8
-------
Mercury can also be leached from its ores and concentrates
with a solution of sodium sulfide and sodium hydroxide, and can
be recovered as the metal by precipitation with aluminum or by
electrolysis. Although leaching of mercury ores has not been
practiced extensively, use of leaching processes may increase in
the future (6-1).
The largest source of waste is residue from the furnace or
retort. In solubility tests leaching of toxic trace metals from
furnace residues was insignificant (less than 0.5 ppm) (6-1).
These calcine residues are designated as nonhazardous and
currently are discharged to open dumps.
Primary Titanium
In 1977 sponge titanium metal was produced by three firms in
Ohio, Oregon, and Nevada, with more than half of the production
in Nevada. The three sponge metal producers and five other firms
in California, Michigan, North Carolina, and Pennsylvania purify
the sponge metal in electric furnaces to yield titanium ingots.
In production of titanium sponge, rutile concentrates
containing 94 percent Ti02 are treated with chlorine gas to
produce titanium chloride gas (TiCl4), which is then condensed,
reduced with magnesium metal, and purified with aqua regia to
produce titanium sponge. The titanium sponge is then melted and
purified in an electric furnace to produce pure titanium ingot.
Magnesium chloride from the reduction process is electrolyzed to
produce chlorine gas and magnesium metal, which are recycled.
6-9
-------
Impurities in the rutile feed are mainly aluminum,
columbium, iron, silicon, vanadium, and zirconium. These
elements plus some of the carbon, chlorine, and titanium
contained in the chlorination mix and in the condenser form
sludges, which are discharged to a pond. Sponge is melted in a
vacuum furnace, which produces no slag. Much of the chlorine
used in chlorinating the rutile, and the sodium or magnesium used
in reducing TiCl^ to metallic titanium, are recovered by
electrolysis and recycled in the process (6-1).
Sludges from the chlorinator and the condenser are the only
significant solid wastes; virtually no solid wastes are
associated with the sponge metal refining operations. It has
been stated that chlorinator and condenser sludge is about 40
percent water-soluble and that the water-soluble portion contains
potentially hazardous chloride and chloride-oxide complexes of
chromium, titanium, vanadium, and other heavy metals (6-3). In
addition, hydrogen chloride gas may be released to the atmosphere
in an anaerobic environment. The chlorinator sludge is
designated as nonhazardous (Tables 6-1 and 6-2).
The chlorination sludge is usually discharged to settling
lagoons and the solids are subsequently placed in a sanitary
landfill.
Secondary Smelting and Refining of Copper
There are an estimated 46 secondary domestic copper smelters
(6-4). Not all recovery of copper from scrap is done at
secondary copper smelters. Of 1.30 million tons (1.18 Tg) of
6-10
-------
copper recovered in 1972, 28 percent was from primary producers,
44 percent from brass mills, and 23 percent from secondary
smelters (6-4). The remaining 5 percent was reclaimed at
chemical plants, foundries, and manufacturers. Brass mills
engage in scrap melting only, and as a result produce negligible
waste.
Secondary copper facilities use pyrometallurgical and
electrolytic processes. The typical secondary copper operation
produces copper and also brass and bronze alloys by
pyrometallurgical processes. Electrolytic refining is more
prevalent in the primary copper industry. The major source of
solid wastes in the secondary copper smelter is the blast furnace
(6-1).
Blast furnace processing in the secondary copper smelting
plant is mainly for recycling of drosses, skimmings, and slag
waste accumulated from melting and smelting of high-grade scrap.
The blast furnace may be operated only when enough waste
byproducts are accumulated to provide at least 1 week of
continuous furnace operation. Only about 20 secondary copper
smelting plants in the United States process scrap in a blast
furnace (6-1).
During processing in a cupola or blast furnace, mixtures of
low-grade scrap are melted with flux chemicals, such as
limestone, borax, and waste glass. Coke is charged to reduce the
copper compounds to metal. The intermediate metal product is
known as black copper. Black copper is further refined in
converter and anode furnaces, where the metal impurities are
6-11
-------
converted to oxides and removed with the added flux as slag. The
slag is recycled to the blast furnace for further copper recovery
(6-5).
Because of its high zinc content, blast furnace dust can be
recycled for manufacture of zinc compounds, largely as paint
additives. This byproduct is sold to chemical and paint
manufacturers and does not require disposal by the smelter.
The principal difference between secondary copper plants
using strictly pyrometallurgical processes for refining and those
using electrolytic refining is that the copper from the
reverberatory furnace is further refined by first dissolving in
sulfuric acid and then electrolytically redepositing pure copper
on the cathodes of electrolytic cells. Lime treatment of spent
electrolyte generates a predominantly lime sludge containing
significant concentrations of nickel, zinc, copper, chromium, and
cadmium (6-1).
Currently slags from pyrometallurgical and electrolytic
plants are disposed of by either onsite or offsite open dumping.
Watewater sludges from the electrolytic plant are discharged to
unlined lagoons for settling. Both of these solid wastes are
designated as potentially hazardous.
Secondary Smelting and Refining of Lead
There are approximately 120 secondary lead smelters in the
United States (6-2). Scrap battery wastes are by far the most
important source for recovery of secondary lead. The recovered
6-12
-------
lead is most often returned to use in battery manufacture. The
lead oxide paste used in the plates must be manufactured from
antimony-free soft lead. Both soft and hard lead can be produced
from scrap battery waste. Soft lead is recovered by
reverberatory smelting, and the recovered metal is converted to
lead oxide either by the Barton process or by a milling process.
The reverberatory slag is then smelted in a blast furnace for
recovery of antimonial lead, with scrap iron as reducing agent.
Alternatively, scrap battery waste may be smelted directly in the
blast furnace to yield only hard lead (6-1).
Secondary lead smelting operations differ somewhat according
to the type of products. The three major products include: hard
lead (antimonial lead), containing about 5 percent antimony; soft
lead, which is pure lead; and white metal, which consists of
lead-tin alloys (about 20 percent tin and 80 percent lead).
Individual plants may produce any or all of these products, in
amounts that vary widely. Lead from discarded storage battery
plates constitutes well over 50 percent of the secondary lead
recovered. Individual plants may operate reverberatory furnaces
to produce soft lead, or cupola or blast furnaces to produce
antimonial lead, or a combination thereof to produce both. The
reverberatory and the blast furnaces are operated continuously.
Soft and Antimonial Lead—In making soft lead, byproduct
slag is sent to a blast or cupola furnace as input for production
of antimonial lead (i.e., hard lead). The emissions from the
reverberatory furnace are collected in a baghouse and immediately
6-13
-------
recycled. Currently, land disposal of the wastes is done only by
one plant in Pennsylvania, which uses a lime scrubber system that
generates a sulfate sludge. No other secondary lead smelters are
known to be using scrubbers for sulfur dioxide removal.
With direct blast-furnace smelting of scrap battery waste to
produce antimonial lead, the sulfur constituent is scavenged by
iron, leading to formation of both a matte and a slag, together
with the molten metal. About 25 percent of this matte and slag
mixture is recycled as flux for subsequent smelting. The former
is typically a mixed silicate, and the latter is mainly a mixed
sulfide. The slag and the matte are tapped together and cast
into a solid mass before land disposal (6-1).
White Metal—Secondary white metal smelting consists of
recovering lead-tin alloys from solder, babbit, and type metal
wastes. Content of the white metal product averages about 20
percent tin and 80 percent lead. With high-grade scrap as feed,
white metal is recovered simply by remelting in a pot furnace.
With low-grade drosses and skimmings, the metal is recovered by
smelting in a reverberatory furnace with limestone, silica, and
iron scale flux (6-1).
Flue dust from the reverberatory furnace is controlled by
baghouses. Although composition of the flue dust varies with the
scrap being smelted, the dust is not directly recyclable to the
smelting furnace because of its high zinc content. It is
subjected to leaching with dilute sulfuric acid to remove zinc
and the residue is recycled. The leaching solution is
6-14
-------
neutralized and stored in a lagoon. Composition of slag from the
reverberatory furnace also varies somewhat according to the
quality of the scrap being smelted (6-1).
Scrubber sludges and acid leach solids are designated as
potentially hazardous, and the slags from the"blast furnaces,
cupola furnaces, and reverberatory furnaces are designated
nonhazardous.
Currently, all furnace slags from secondary lead smelting
are disposed of by open dumping on land. Solutions from acid
leaching of baghouse dust and scrubber sludge are disposed of in
unlined lagoons.
Secondary Smelting and Refining of Aluminum
The secondary aluminum smelting and refining industry
consists of a large number of relatively small operations in
urban areas throughout the United States. Many of these plants
remelt only high-grade scrap and generate little waste.
Scrap Melting--High grade aluminum scrap is easily recycled
by remelting in pot or rotary furnaces. Low-grade scraps and
foundry drosses are smelted in reverberatory or rotary furnaces.
Fluxing and alloying agents are charged with the scrap.
Magnesium is removed by treatment with AlF^ or chlorine.
Degassing is usually done simultaneously with the demagging
operation. Upon completion of smelting, the fluxing agent is
skimmed and the purified metal melt is poured and cast into
ingots. Common salt and potash mixtures are used as fluxing
agents (6-1).
6-15
-------
In aluminum scrap smelting, the byproduct slag or dross
consists mainly of a salt mixture of sodium chloride (NaCl),
potassium chloride (KC1), and magnesium chloride (MgC^), with
about 15 percent aluminum. Currently, this slag is further
processed in plants with dross smelting capabilities. It may
present a disposal problem in the future if dross smelting for
further metal recovery becomes unprofitable or impractical.
Byproduct dross is stored in covered areas with no danger of salt
leaching (6-1).
Another waste associated with scrap smelting consists of
sludge generated in wet scrubbing with lime as an air pollution
control measure.
Dross Smelting—About 10 to 15 percent of all secondary
aluminum metal is produced from dross smelting. The low-grade
drosses containing 10 to 30 percent aluminum metal are
preprocessed to enrich the aluminum metal content to about 75
percent. In wet processing, the flux salt remaining from dross
enrichment is removed by dissolution in water. In dry
processing, the flux salt is recovered as A^O^, which is
recycled as steel melting flux cover agent. The major solid
wastes arise from the impure constituents in the enriched dross
and the salt flux used in the smelting process. The waste is
generated in the form of a slag with high salt content, mainly
sodium chloride and potassium chloride with about 6 to 8 percent
residual aluminum. The furnace releases relatively small
quantities of flue dust, which is combined with the slag waste.
6-16
-------
Scrubber sludge from aluminum scrap melting is designated as
nonhazardous and the high-salt slag as potentially hazardous.
Currently wet scrubber sludge from secondary aluminum
smelters is usually placed in unlined lagoons. The high-salt
slag from dross smelting is open dumped. It is estimated that on
a national basis about 50 percent of the slag is disposed of
onsite and 50 percent offsite by contracted disposal service
(6-1).
Alternative Controls and Costs
Alternative control measures for meeting the proposed RCRA
Criteria for nonhazardous wastes were not determined for
individual minor primary and secondary nonferrous smelting and
refining industries. The control measures applicable to these
industries are essentially those described in detail earlier in
connection with the major industries, including: relatively
intensive site selection, extensive site preparation, lagoon
lining, ground sealing, a seepage collection system, runoff
collection and diversion ditches, wells for monitoring
groundwater, flood protection dikes, access control (fencing),
closure of existing sites, and postclosure monitoring and
maintenance. The need for these alternative controls would be
assessed on a site-specific basis. Based on the cost of control
per unit of solid waste generated for the major primary
industries, it is roughly estimated that the total incremental
cost for controlling nonhazardous solid wastes generated by the
6-17
-------
seven minor primary and secondary smelting industries discussed
above would be:
Capital cost: $16 million*
Annual cost: $2.5 million/yeart
These costs include both state-standard induced costs and
Criteria-induced costs.
* Based on a $30 per ton of solid waste ($33/Mg).
t Based on $5 per ton of solid waste ($5.50/Mg).
6-18
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REFERENCES
6-1. Calspan Corporation. Assessment of industrial hazardous
wastepractices in the metal smelting and refining
industry. Solid Waste Management Series Publication
SW-145c.2, Volumes 1 and 2. Environmental Protection
Agency, Solid Waste Management Division, Washington, D.C.
1977.
6-2. U.S. Bureau of Mines. Mineral commodity summaries 1979.
Washington, U.S. Department of the Interior.
6-3. Merrill, C.C., M.M. Wong, and D.D. Blue. Beneficiation of
titanium chlorination residues. U.S. Bureau of Mines
Report of Investigation 7221, 1969.
6-4. Personal communication. H.J. Schroeder. Division of
Nonferrour Metals, U.S. Bureau of Mines, to R.S. Amick,
PEDCo Environmental, Inc., February 13, 1979.
6-5. Coltharp, W.M., G.C. Page, W.E. Corbett, and N.P. Phillips.
Multimedia environmental assessment of the secondary
nonferrous metal industry. U.S. Environmental Protection
Agency. Industrial Environmental Research Laboratory,
Office of Research and Development, Contract 68-02-1319,
Task No. 49, by Radian Corporation. November 1976.
6-19
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APPENDIX A
The agencies and their personnel who meet with PEDCo
personnel during the course of this study are listed below:
U.S. Environmental Protection Agency, Office of Solid Waste,
Washington, D.C.
Janet Auerbach
Tim Fields
Jon Perry
Joanne Slaboch
Larry Weiner
U.S. Environmental Protection Agency, Industrial Environ-
mental Research Laboratory, Cincinnati, Ohio.
John Burckle
U.S. Environmental Protection Agency, Region 6, Dallas,
Texas.
Jim Sales Solid Waste Branch
Fred Humpke Water Enforcement Branch
Ken Hurly Water Enforcement Branch
Jack Ferguson Water Enforcement Branch
John Dehn Water Enforcement Branch
Bruce Hale Water Enforcement Branch
Joe Winkler Air Programs Branch
Carl Edlund Air Programs Branch
U.S. Environmental Protection Agency, Region 7, Kansas City,
Missouri.
Ron McCutcheon
Ralph Summers
Gayle Wright
U.S. Environmental Protection
Colorado.
Rob Wallen
Water Enforcement Branch
Water Enforcement Branch
Air Enforcement Branch
Agency, Region 8, Denver,
Water Enforcement Branch
A-l
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U.S. Environmental Protection
Francisco, California.
Larry Bowerman
Terry Stump
Mike Reed
U.S. Environmental Protection
Washington.
George Hofer
Neal Thompson
Stan Jorgensen
U.S. Environmental Protection
Investigation Center, Denver,
Wayne Smith
Jim Hathaway
Bob Gosik
Ed Struzeski
Dave Brooman
Richard Ida
U.S. Bureau of Mines, Metallurgical Research Center, Reno,
Nevada
Tom Cornahan
Phil Haskett
Bernie Schneiner
Frank Haver
U.S. Bureau of Mines, Metallurgical Research Center, Rolla>
Missouri.
Morris Fine
Ernest Cole
Waldemar Dressel
Dan Paulson
James Stevenson
U.S. Bureau of Mines, Metallurgical Research Center,
Tuscaloosa, Alabama.
Martin Stanczyk
Gerald Sullivan
Don Stanley
Agency, Region 9, San
Air Enforcement Branch
Air Enforcement Branch
Water Enforcement Branch
Agency, Region 10, Seattle,
Office of Air Programs
Office of Solid Waste Liaison
Solid Waste Management
Agency, National Enforcement
Colorado.
A-2
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U.S. Bureau of Mines, Metallurgical Research Center, Albany,
Oregon.
Jim Marcellus
Jack Henry
Willard Hunter
Texas Air Control Board, Austin, Texas.
James Caroway
Lawrence Pewitt
A-3
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APPENDIX B
Historic data are tabulated for the years 1967 and 1977, and
maximum and minimum scenarios are presented for the years 1980,
1984, and 1987. Definition of maximum and minimum scenarios is
as follows:
Sludge Generation as a result of the Clean Air Act
° Maximum Scenario - assumes that all copper smelters
achieve full compliance with the primary and secondary
National Ambient Air Quality Standards (NAAQS) by 1987
through the use of lime or limestone scrubbing of weak
SC>2 streams.
° Minimum Scenario - Assumes that sources presently out
of compliance do not come into compliance on schedule
due to litigation and enforcement problems, or they
come into compliance without flue gas desulfurization
technology by incorporating, for example, design or
process changes. Another contributing circumstance to
this scenario would be relaxation of SO~ standards by
EPA. This, however, is unlikely.
Sludge Generation as a result of the Water Pollution Control
Act
° Maximum Scenario - assumes that industrial dischargers
must implement Best Available Technology (BAT)
regulations on schedule.
° Minimum Scenario - assumes that effluent guidelines are
relaxed and that Best Practible Control Technology
Economically Achievable (BPT) is adequate to meet the
goals of the act. It further assumes that discharge of
trace toxics is not a problem and guidelines are not
required.
B-l
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APPENDIX C
DESIGN PARAMETERS AND COST FACTORS FOR
WASTE CONTROL TECHNOLOGIES
The basic approach to solid waste control in the primary
nonferrous metals industries has been land disposal of slags;
potliners, sludges, and other process residuals. The deployment
of synthetic liners, soil sealants, leachate collection systems,
monitoring wells, and other environmentally sound technologies
has not been widespread with the exception of recently
constructed plant sites. These technologies are the basis of the
alternative control systems. The design parameters and cost
factors employed in this study for both the current and
alternative systems (including closure of existing facilities)
are presented here. All costs are in 1978 dollars.
Data sources for developing costs are as follows:
° Godfrey, R. S., ed. Building construction cost data.
36th ed. Robert Snow Means Company, Inc. Duxbury,
Mass. 1978.
0 Office of Solid Waste. Assessment of industrial
hazardous waste practices in the metal smelting and
refining industry. V. 4. EPA Publication SW-145. C.
1. National Technical Information Service.
Springfield, Virginia. 1977.
° Office of Solid Waste. Alternatives for hazardous
waste management in the metals smelting and refining
industries. EPA Publication SW-L53C. 1978.
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° Assessing Synthetic and Admixed Materials for Lining
Landfills; Proceedings; Research Symposium, Rutgers
University, March 25 and 26, 1975. New Brunswick, New
Jersey. EPA Publication EPA-600/9-76-004. March,
1976.
Capital Costs
All capital charges used in the report represent the
installed capital cost of each item in 1978 dollars. A 10
percent contingency charge is added to all capital costs in the
current system and a 15 percent contingency charge is added with
the alternative system.
Site Selection
The site selection process called for in the alternative
system requires one engineer-man-year to assess such factors as
topography, soil type (both surface and underground), chemistry,
and permeability, and long range land use and planning
considerations. The first step in the site selection process is
to select two or three potential waste disposal sites. At each
potential site test wells collect underground soil and
hydrogeological samples for analysis. The collected samples are
analyzed and a report prepared upon which site selection can be
based.
The estimated cost of this activity is $59,800.
1 engineer-man-year $41,600
Hydrogeological survey 16,200
Report 2,000
$59,800
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Land
Rural land was assumed for use as solid waste disposal
sites. Land costs are based on a cost factor of $971 per acre.
The size of land disposal areas were calculated using current
waste generation factors, waste densities and a site life of 20
years.
Construction
Survey—Survey costs of $375 per acre are limited to
definition of boundaries and general topographic information.
Site Preparation—Site preparation for the current system is
valued at $200 per acre and consisted of clearing the surface of
trees and vegetation and grubbing the area. Site preparation
cost in the alternative system was increased to $530 per acre to
include removal and storage of topsoil and surface grading.
Rail Spur—Construction costs of a rail spur for slag
transport amounted to $206,000 per mile. The cost was based on a
one-mile, single track on level ground with a 12-foot sub-base.
Miscellaneous bulldozing represents three-man-days of labor and
3
movement of 1700 yd of earth. Itemized cost factors are:
O
Survey ($375 per acre)
$ 550
4,750
O
Miscellaneous bulldozing
($1.61 per yd )
0
Track
100-lb rail ($9.00 per ft.)
Spikes, plates, and bolts
($3.60 per ft.)
Timber ties ($6.00 per ft.)
Ballast ($4.40 per ft.)
Labor ($14.50 per ft.)
47,500
19,000
31,700
23,200
76,600
Total
$206,000 per mile
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Road Construction—Construction costs of a road to transport
solid waste to the disposal site amounted to $31,200 per mile.
The cost is based on a one mile, 20-foot wide gravel road with a
drainage ditch along one side. Miscellaneous bulldozing
3
represents three-man-days of labor and movement of 2,800 yd of
earth. Road gravel is 3-in. thick.
Survey ($375 per acre) $ 900
Miscellaneous bulldozing 4,500
($1.61 per yd )
Base preparation and roll sub-base 7,900
($0,075 per ftz)
Base course select gravel 12,200
Drainage Ditching ($1.08 per ft.) 5,700
Total $31,200 per mile
Alternative Controls; Leachate Collection System--A drain
field consisting of perforated 4-inch diameter PVC pipe having
lengths equal to one side of the disposal site or the impoundment
diameter are placed in parallel with 50-foot spacing beneath both
disposal sites and surface impoundments in the alternative
system. A transverse pipe, also the length of one side of the
disposal site or impoundment diameter, serves to connect the
drain pipes and to carry the leachate, if any, to a sump where a
pump is available to move the leachate to its ultimate
destination. A soil-cement pad is installed above the drain
field of land disposal areas to minimize leaching provide
structural support and promote controllable runoff. A synthetic
liner, 30-mil thick hypalon, and 18-inches of protective soil are
installed in all surface impoundments. The installed cost
factors of these materials are presented below:
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o
4-inch, PVC, perforated pipe $ 2.10 per ft-
0 Soil cement 1.70 per ycL
0 Synthetic liner 4.16 per yd3
° Soil cover 2.04 per yd
0 Sump 600.00 (unit price)
0 Pump 2,500.00 (unit price)
Surface Impoundments—Surface impoundments are circular in
design and sized to represent typical impoundments currently used
by industry. The lagoon is surrounded by a dike the dimensions
of which appear in the sketch below:
h- 5'-H
Cross Sectional Area = 102 ft
Cross Sectional Length = 32 ft^
Material for dike formation is provided by excavation of the
interior area. Construction costs are:
Excavation and forming
Compaction
Fine grading
$1.60 per yd-
$2.14 per yd ~
$0,065 per ftz
Equipment
Equipment costs are provided in those cases where wastes are
transported from one location to another as in slag transport or
dredging. Equipment costs are allocated to specific activities
based on an estimate of the number of hours the equipment is
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engaged in that activity, a usage factor. For example, an
industrial yard engine may be engaged in hauling slag 10 percent
of the time, and 90 percent of the time used to transfer raw
materials. Therefore a 10 percent usage factor is applied to the
total capital cost to determine the applied cost. Capital costs
for equipment are as follows:
0 Industrial yard engine (used) $ 44,000
0 Flat car (used) 5,000
° Dump truck 37,000
° Front loader and backhoe 29,000
° Bulldozer 23,500
° Dragline with 3/4 yd clamshell 103,000
° Hopper car (100 ton) 10,000
0 Ladle car 59,000
° Tank truck 59,000
0 Slag pot 3,500
0 Rubber tired slag pot carrier 37,000
In addition to the specific pieces of equipment listed
previously there are equipment or systems used for a specific
purpose in one or two industries. For example impoundments are
often dredged with a slurry pump instead of a dragline.
Therefore a slurry dredging system was developed. The system
includes a 2 HP slurry pump with motor, 600 feet of installed
pipe, and 900 feet of flexible pipe. Capital costs are listed
below:
Slurry pump (2 HP) $4,800
3" Pipe, rigid ($4.70 per foot) 600
3" Pipe, flexible ($1.82 per foot) 1,600
Total 7,000
All plants represented by Model 1 of the lead industry
granulate their slag and then dewater the granulated slag before
hauling it to the disposal site. These plants use a dewatering
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tower and bucket elevator in the dewatering system. Unit costs
for the system are:
Installed dewatering tower cost $26,000
Pad and foundation 20,000
Bucket elevator (installed) 31,000
Total 77,000
Also in the lead industry one Model 2 plant granulates the
slag and pumps it as a slurry to the slag pile. The pumping
system consists of three 75-HP pumps, 1,500 feet of 8-inch
pressure pipe, a concrete granulation pit, and a concrete sump.
Installed costs for the equipment are:
75-HP pump ($11,000 installed) $33,000
8-inch pipe ($7.71 per foot) 11,600
8-inch pipe fittings 2,200
Granulation pit 22,800
Sump 1,100
Total 70,700
Monitoring Wells—Six monitoring wells, placed both
upgradient and downgradient of the disposal area, are provided
for each plant in the alternative system. Placement of the wells
is similar but not identical to the system proposed in the
hazardous waste regulations. One well is placed hydraulically
upgrade of the waste disposal area to collect background data.
Two wells are located near and hydraulically downgrade of the
waste disposal area (one by a surface impoundment and one by land
disposal). Two more wells are located hydraulically downgrade
and away from the waste disposal area. The remaining well may be
located wherever desired to monitor groundwater but is generally
located upgrade of the waste disposal site.
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All wells are drilled to a depth of 100 feet. Itemized cost
factors per well are:
Drilling:
80-feet unconsolidated earth ($13.00 per foot) $1,000
20-feet bedrock ($15.00 per foot) 300
100-feet 2.5-inch schedule 40 PVC pipe 800
($7.95 per foot installed)
Rig and crew ($325.00 per day) 650
Total 2,750
The installed capital cost of all wells is $16,500.
Flood Dikes—Flood dikes were placed around the perimeter of
the slag disposal and potliner storage areas to prevent
inundation by floodwaters. The dike is installed 30-feet from
the edge of the disposal site. The design parameters and
construction costs are identical to those of the impoundment
dike. No costs for flood diking were allocated to surface
impoundments because the impoundment dike is the same heighth as
the flood dike and therefore provides the same degree of
protection. Refer to the text for distribution of flood dikes
within each industry.
Fencing—The alternative system provides a continuous
security fence around the perimeter of the entire disposal area.
The disposal area includes both land disposal sites, including
flood dikes, and surface impoundments which are assumed to be
situated adjacent to one another. A 50 foot (15m) buffer zone is
provided between the disposal area and fence. The installed
capital cost is calculated at $10.00 per foot.
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Collection and Diversion Ditching—In all cases it is
assumed that the ground at the disposal site has a slight slope
and surface runoff needs to be diverted and collected, ditching
is provided both upgradient and downgradient of the site with a
total length of 3.0 times the length of one side of the square
disposal site. The installed capital cost of ditching is $4.53
per foot.
Closure of Alternative Disposal Sites
The capital cost of closure is composed of the following
activities: covering the waste pile with two-feet of soil, the
bottom 6-inches of which is a low permeability soil that is
covered with topsoil; compacting the bottom layer of soil; fine
grading the soil cover; and revegitation of the topsoil. The
itemized cost factors for these activities are:
3
° Excavation and placement $1.60 per ydg
0 Compacting 2.14 per yd „
0 Grading 0.065 per ft
° Revegitation 1000.00 per acre
To ensure the total closure capital cost is available at the
end of site life a trust fund is established for closure before
the site is used. The amount of capital deposited in the trust
fund is the closure capital cost divided by the interest factor,
1.4859 calculated assuming a 2 percent real interest rate for 20
years.
Postclosure of Alternative Sites
Postclosure activities consist of groundwater sampling and
analysis, and maintenance of the drain system, monitoring wells,
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fence, and vegetation. The individual cost factors on an annual
basis are:
° Fencing - one percent of the installed capital cost of
the fence.
° Vegitation - five percent of the installed capital
cost of the vegitation.
° Drainfield - five percent of the installed capital cost
of the drainfield.
° Sampling and analysis - fixed cost at $20,000 annually
which includes maintenance costs
for the monitoring wells.
The total annual cost of these activities is multiplied by
20 years (the length of the performance period) to determine the
total capital requirements. Again to ensure the total capital
will be available a trust fund is established to provide the
required funds. The interest rate is assumed to be a real
interest rate of 2 percent.
The required deposit in the trust fund was determined by
first calculating the amount of capital necessary in the trust
fund at all time of closure using a present worth factor
(0.8242). Then the initial capital required for the trust fund
is calculated by the same method as closure.
Closure of Existing Disposal Sites
The capital cost of closure is based on the following
activities: covering the waste pile with two feet of soil, the
bottom 6-inches of which is a low permiability soil which is
covered with topsoil; compacting the bottom layer of the soil
cover; grading the soil cover; and revegitation of the topsoil.
The itemized cost factors for these activities are:
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3
0 Excavation and placement $ 1.60 per yd_
0 Capacting 2.14 per yd ~
0 Grading 0.065 per ft
° Revegitation 1,000.00 per acre
The volume of wastes stored onsite was estimated to determine the
disposal site area requiring closure. At those plants where the
waste disposal site size was known from site visits the actual
area was closed.
Annual Costs
Amortization of Capital Costs
The capital costs of land, site selection, construction,
closure, and post-closure were annualized over a period of 20
years at a 10 percent interest rate. Substituting these data
into the formula below yields an amortization factor of 0.117.
The capital cost of equipment is annualized over a period of
10 years at a 10 percent interest rate yielding an amortization
factor of 0.163.
= r (1+r )N
A (l+r)N - 1
where
C. = annual amortization factor
A
r = interest rate
N = number of years
Operating and Maintenance Costs
Personnel—Personnel costs are calculated from the estimated
number of hours the personnel were engaged in waste control
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activities. An additional charge is included for the foreman's
supervisory time. This charge is 20 percent of the foreman's
rate added per hour of operating time. Hourly rates are based on
the following labor rates plus a 25 percent charge for fringe
benefits.
0
Dump truck driver
$10.05
per
hour
o
Front loader operator
11.95
per
hour
o
Dragline operator
12.60
per
hour
o
Foreman
14.40
per
hour
o
Engineer (yard engine)
13.00
per
hour
o
Trainman
10.00
per
hour
o
Laborer
8.00
per
hour
Maintenance—Maintenance charges were calculated by
multiplying the capital cost of each item by the appropriate
maintenance factor listed below:
O
Road and rail spur
5
percent
O
Soil cement pad
5
percent
0
Drain field
5
percent
o
Liner
5
percent
o
Soil cover
5
percent
0
Ditching
5
percent
o
Fencing
5
percent
o
Equipment
5
percent
0
Surface impoundment
3
percent
o
Flood dike
3
percent
Fuel and Electricity—Total fuel costs are calculated from
the number of operating hours for each piece of equipment, fuel
consumption, and a fuel cost of $0.60 per gallon. Fuel
consumption is based on the following rates:
Dump truck
Front loader
Dragline
Bulldozer
4 gallons per hour
3 gallons per hour
3 gallons per hour
3 gallons per hour
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Electricity costs are calculated, except where noted, by the
following formula and assuming an electricity charge of $0.06 per
kilowatt hour:
KWH = HP x OH x 0.7457
where
KWH = kilowatt hours of electricity
HP = horsepower of pump
OH = number of operating hours per year
Sampling and Analysis—A fixed annual cost of $20,000 per
plant was assumed to be sufficient to cover costs of monitoring
well maintenance, quarterly groundwater sampling and analysis,
sampling technicians time and report preparation.
Taxes—Taxes are two and one-half percent of the total land
capital cost.
Insurance—Insurance charges are calculated as one percent
of the total capital cost of the control system.
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