Prepublication issue for EPA libraries
and State Solid Waste Management Agencies
ENVIRONMENTAL IMPACTS
OF VIRGIN AND RECYCLED STEEL AND ALUMINUM
This.final report (SW-ll?c) describes work performed
for the Federal solid waste manag&ngnT programs under contract No. 68-01-0794
and is reproduced as received from the contractor
Copies will be available from the
National Technical Information Service
U.S. Department of Commerce
Springfield, Virginia 22151
U.S. ENVIRONMENTAL PROTECTION AGENCY
1976
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This report has been reviewed by the U.S. Environmental Protection
Agency and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of commercial products
constitute endorsement by the U.S. Government.
An environmental protection publication (SW-117c) in the solid waste
management series.
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ABSTRACT
This study has analyzed the environmental impacts which result
from the production of selected products which use virgin materials
and various amounts of recycled ferrous metals and aluminum.
Determinations were made of the material, water, and energy
requirements of all stages of virgin and waste materials acquisition,
transportation and processing, as well as secondary effects such
as energy use. Also determined were the outputs at each stage
including solid, airborne and waterborne waste that are generated,
assuming EPA Air Standards for FY 1975 and Water Standards for FY
1977. The virgin and waste materials systems were analyzed up to
the processing point at which materials are comparable. Estimates
were also made of the dollar costs to industry to meet 1975 Air
Standards and 1977 Water Standards,
Nine systems which produce carbon steel from virgin materials and/or
obsolete scrap were examined. The environmental impact analysis
for these systems showed that steel production from virgin materials
had the highest environmental impacts of these systems. In addition,
six systems which produce aluminum from virgin materials or obsolete
scrap were examined. The environmental impact analysis for these
systems show that aluminum production from virgin materials had the
highest environmental impacts of these systems.
ACKNOWLEDGMENTS
The authors wish to thank Dr. Frank A. Smith, EPA Project
Officer for his guidance and helpful suggestions throughout
the program. The willingness of the private industrial sector
and the trade associations to disclose proprietary information
is deeply appreciated. The assistance of several government
agencies, as well as private individuals, is also appreciated.
Special thanks are due several individuals at Calspan Corporation
for their participation. In particular, H. G. Reif and G. M.
Niesyty, Jr., who prepared the analyses on pollution control
costs,.and D. B. Dahm and J. Y. Yang for their helpful suggestions.
111
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TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS iii
ABSTRACT iii
Sections
I SUMMARY 1
Steel 1
Aluminum 2
General 3
II INTRODUCTION 5
III STUDY APPROACH AND METHODOLOGY 9
Basic Approach 9
Assumptions 13
Limitations 14
IV AUXILIARY MODULES 17
Introduction 17
Energy 17
Transportation 25
Resource Recovery 30
43
V STEEL
Steel from Virgin Materials ................... ^
Steel from Recycled Materials ................. 56
Steel Systems Synthesis ....................... 62
Environmental Impact Comparisons .............. 73
Pollution Control Costs for Steel ............. 76
IV
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TABLE OF CONTENTS (Cont'd)
Page
VI. ALUMINUM 78
Aluminum from Virgin Materials 78
Aluminum from Recycled Materials. 88
Aluminum Systems Synthesis 97
Environmental Impact Comparison 99
Pollution Control Costs for Aluminum 107
REFERENCES 110
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LIST OF TABLES
Number
1 Environmental Impact Resulting from Coal Mining
and Transportation 19
2 Module Summary Sheet for Crude Petroleum Extraction 20
3. Environmental Impact Resulting from Extraction,
Transportation, and Refining of 1000 Liters of
Liquid Hydrocarbon Fuel 22
4 Environmental Impact Resulting from Natural
Gas Production and Transportation 23
5 Emission Factors from Stationary Sources 24
6 Environmental Impacts of Electricity Production 26
7 Emissions from Fuel Combustion by Mobile Sources,... 27
8 Fuel Consumption and Environmental Impacts
Resulting from 1000 Metric Ton Kilometers of
Transportation by Each Mode 28
9 Summary Sheet for Auto Hulk Processing 31
10 Summary Sheet for Auto Scrap Processing by a
Shredder 33
11 Summary Sheet for Auto Scrap Processing by Hand
Stripping and a Smokeless Incinerator 34
12 Outputs per Metric Ton of Wet Municipal Solid
Waste Processed 32
13 Module Summary Sheet for Ferrous Scrap Recovery
from Municipal Solid Waste 36
14 Module Summary Sheet for Aluminum Scrap Recovery
from Municipal Solid Waste 37
15 Module Summary Sheet for Aluminum Scrap Recovery
from Aluminum Cans 39
16 Module Summary Sheet for Ferrous Scrap Recovery
from Steel Cans 40
VI
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LIST OF TABLES (Cont'd)
Number
17 Module Summary Sheet for Detinning .................. 42
18 Module Summary Sheet for Iron Ore Mining ............ 46
19 Summary Sheet for Limestone Quarrying ............... 47
20 Environmental Impacts for Lime Production ........... 49
21 Module Summary Sheet for the Blast Furnace .......... 52
22 Module Summary Sheet for Oxygen Production .......... 53
23 Module Summary Sheet for the Basic Oxygen
Furnace (30% Home Scrap) ............................ 55
24 Module Summary Sheet for the Basic Oxygen
Furnace (30% Home Scrap 5 10% Obsolete Scrap) ....... 58
25 Module Summary Sheet for the Electric Furnace
26 Summary Sheet for Carbon Steel Production
From Virgin Materials in the BOF: System Fl ........ 63
27 Summary Sheet for Carbon Steel Production
in the BOF (30% Home Scrap, 10% Obsolete
Scrap from an Auto Shredder) System F2 ..............
28 Summary Sheet for Carbon Steel Production
in the BOF (30% Home Scrap, 10% Obsolete „
Scrap from an Auto Baler) : System F3 ................
29 Summary Sheet for Carbon Steel Production in
the BOF (30% Home Scrap, 10% Obsolete Scrap
from Municipal Solid Waste) : System F4 .............. 67
30 Summary Sheet for Carbon Steel Production in
the BOF (30% Home Scrap, 10% Obsolete Scrap
from Separated Steel Cans): System F5-
68
31 Summary Sheet for Carbon Steel Production in
the Electric Furnace (30% Home Scrap, 70%
Obsolete Scrap from an Auto Shredder): System F6-•••
VII
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LIST OF TABLES (Cont'd)
Number Page
32 Summary Sheet for Carbon Steel Production in
the Electric Furnace (30% Home Scrap, 70%
Obsolete Scrap from an Auto Baler): System F7 °
33 Module Summary Sheet for Carbon Steel Production in
the Electric Furnace (30% Home Scrap, 70%
Obsolete Scrap from Municipal Solid Waste):
System F8 71
34 Module Summary Sheet for Carbon Steel Production in
the Electric Furnace (30% Home Scrap, 70%
Obsolete Scrap from Separated Steel Cans) __
System F9
35 Comparison of Environmental Impacts for the
Production of Carbon Steel Using Virgin and/or
Recycled Materials 74
36 Pollution Control Costs for Steel: Net Annual
Costs 77
37 Module Summary Sheet for Bauxite Mining 80
38 Module Summary Sheet for Mining Rock Salt 82
39 Module Summary Sheet for Caustic Soda or
Chlorine Manufacture 83
40 Module Summary Sheet for Alumina Production 85
41 Module Summary Sheet for Primary Aluminum
Smelting 87
42 Module Summary Sheet for Secondary Aluminum
Smelting (Cans to Sheet) 91
43 Module Summary Sheet for Secondary Aluminum
Smelting (Cans to Low Mg Alloy) 94
44 Module Summary Sheet for Secondary Aluminum
Smelting (Auto Scrap) 95
Vlll
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LIST OF TABLES (Cont'd)
Number Page
45 Summary Sheet for Aluminum Production Using
Virgin Materials (System Al) 98
46 Summary Sheet for Wrought Aluminum Production
Using Scrap Aluminum Cans for MSWR: System A2 100
47 Summary Sheet for Wrought Aluminum Production
Using Scrap Aluminum Cans Collected Separately:
System A3 101
48 Summary Sheet for Cast Aluminum Ingots by a
Secondary Smelter Using Scrap Aluminum Cans
from MSWR: System A4 102
49 Summary Sheet for Cast Aluminum Ingots by a
Secondary Smelter Using Aluminum Auto Scrap
from a Shredder: System A5 103
50 Summary Sheet for Cast Aluminum Ingots by a
Secondary Smelter Using Aluminum Auto Scrap
from a Baler: System A6 104
51 Comparison of Environmental Impacts for the
Production of Aluminum Using Virgin or Recycled
Materials 106
52 Pollution Control Costs for Aluminum: Net
Annual Cost 108
IX
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LIST OF FIGURES
Number Page
1 Summary of Data Presented in Each Module 10
2 Steel Production by the Basic Oxygen Furnace
Using Virgin Materials (Current Mix-30% Home
Scrap; 70% Pig Iron) 44
3 Steel Production by the Basic Oxygen Furnace
Using Obsolete Scrap (Mix-30% Home Scrap; 10%
Obsolte Scrap; 60% Pig Iron) 57
4 Steel Production by the Electric Furnace (Mix-
30% Home Scrap; 70% Obsolete Scrap) 60
5 Primary Aluminum Production from Virgin Materials
Materials 79
6 Sheet Aluminum Production from Aluminum Cans go
7 Cast Aluminum Production from Municipal Solid
Waste 93
8 Cast Aluminum Production from Auto Scrap 95
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SECTION I
SUMMARY
This study has analyzed the environmental impacts which result from
the production of selected products which use virgin materials and
various amounts of recycled ferrous metals and aluminum. Determina-
tions were made of the material, water, and energy requirements of
all stages of virgin and waste materials acquisition, transportation
and processing, as well as secondary effects such as energy use.
Also determined were the outputs at each stage including solid, air-
borne and waterborne waste that are generated, assuming EPA Air
Standards for FY 1975 and Water Standards for FY 1977. The virgin
and wastes materials systems were analyzed up to the processing point
at which materials are comparable. Estimates were also made of the
dollar costs to industry to meet 1975 Air Standards and 1977 Water
Standards.
Steel
Nine systems which produce carbon steel from virgin materials and/or
obsolete scrap were examined in this study. These systems are the
following:
Fl Virgin Materials in the Basic Oxygen Furnace
F2 Virgin Materials and Obsolete Scrap from Auto Shredders in the EOF
F3 Virgin Materials and Obsolete Scrap from Auto Balers in the EOF
F4 Virgin Materials and Obsolete Scrap from Municipal Solid Waste
in the EOF
F5 Virgin Materials and Obsolete Scrap from Separated Steel Cans in
the EOF
F6 Obsolete Scrap from Auto Shredders in the Electric Furnace
F7 Obsolete Scrap from Auto Balers in the Electric Furnace
F8 Obsolete Scrap from Municipal Solid Waste in the Electric Furnace
F9 Obsolete Scrap from Separated Steel Cans in the Electric Furnace
The total environmental impacts for these systems are presented in Table
35. A comparison of the impacts of the systems revealed that System Fl
which consumes virgin materials in the B.O.F. has the highest environ-
mental impacts. The impacts from Systems F2, F3, F4, and F5 which con-
sume virgin materials and obsolete scrap in B.O.F. are slightly less
than those from System Fl. However, Systems F2, F3, F4, and F5 use
only a 10% obsolete scrap charge. Therefore, if the impacts from the
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resource recovery processes were zero, only a slight change would be
expected between System Fl and Systems F2, F3, F4, and F5. It was
also determined that there was very little difference in the impacts
between Systems F2, F3, F4 and F5.
Systems F6, F7, F8 and F9 which consume obsolete scrap in the electric
furnace had the lowest environmental impacts of all the steel systems
studied. The greatest changes were seen in raw material consumption,
water use, energy consumption and solid wastes. System F6 had the
minimum environmental impacts of systems which consume obsolete scrap
in the electric furnace while System F9 had the greatest. The impacts
of these systems were determined largely by the amount of energy con-
sumed.
Since 1975 Air Standards and 1977 Water Standards were assumed to be
met when air and water wastes were reported, the direct costs to the
steel industry in meeting these standards were determined for the
systems studied. The control costs for System Fl which consumes vir-
gin materials in the B.O.F. are $5.58-6.46 per metric ton of steel.
Pollution control costs for Systems F2, F3, F4 and F5 which consume
virgin materials and obsolete scrap in the B.O.F. are $4.97-5.79 per
metric ton of steel. Systems F6, F7, F8 and F9 which consume obsolete
scrap in the electric furnace have the lowest control costs, $2.30 per
metric ton of steel.
Aluminum
Six systems which produce wrought and/or cast aluminum from virgin
materials or obsolete scrap were examined in this study. These
systems are the following:
Al Aluminum Production from Virgin Materials
A2 Wrought Aluminum Production Using Obsolete Scrap from Municipal
Solid Waste
A3 Wrought Aluminum Production Using Obsolete Scrap from Separated
Aluminum Cans
A4 Cast Aluminum Production Using Obsolete Scrap from Municipal
Solid Waste
AS Cast Aluminum Production Using Obsolete Scrap from Auto Shredders
A6 Cast Aluminum Production Using Obsolete Scrap from Auto Balers
The total environmental impacts for these systems are presented in
Table 51. A comparison of the impacts of these systems revealed that
System Al which consumes virgin materials has the highest environmental
impacts. Systems A2 and A3 which produce wrought aluminum products
from can scrap have the lowest environmental impacts, with System A3
slightly superior to System A2.
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Systems AS and A6 which produce cast aluminum from auto scrap have
environmental impacts which arc slightly greater than Systems A2 aiul
A3 but much less than System Al.
System A4 which produces cast aluminum using scrap from municipal
solid waste has environmental impacts which are much greater than
Systems A2, A3, AS and A6, but somewhat less than System Al. Com-
pared with System Al, System A4 greatly reduced raw materials con-
sumption, water discharged, energy consumption, solid wastes and air
emissions. However, System A4 produces considerable chloride emis-
sions and water pollutants.
Costs to the aluminum industry in meeting 1975 Air Standards and 1977
Water Standards were determined. Pollution control costs for System
Al which produces aluminum from virgin materials are $10.91 to 15.33
per metric ton of aluminum. Systems A2, A3, A4 and AS which produce
aluminum from scrap materials have costs for pollution control which
range from $4.98 to 10.10 per metric ton of aluminum. Systems such
as A2 and A3 which use a minimum amount of chlorine would be in the
low end of the range while System A4 which uses a large amount of
chlorine would be in the high end of the range.
General
The assumption that 1975 Air Standards and 1977 Water Standards would
be met had a great effect on the results of this study. These standards
are presumably set to stop environmental degradation. In most instances,
these standards are directly related to the amount of product produced.
Therefore, processes which have more environmental impacts than others
when uncontrolled have similar impacts when controlled. In this study,
the specific effects of processes were less noticeable than the second-
ary environmental impacts of energy use. All energy used in this study
came directly or indirectly from fossil fuels. It was the environmental
impacts which result from the extraction, processing, and combustion of
these fuels which became dominant factors in this study.
The outstanding exception to this situation was System A4 which produced
cast aluminum using scrap from municipal solid waste. This system
requires the use of a large amount of chlorine by secondary smelters
to remove magnesium. Standards for secondary aluminum smelters are
written in terms of the amount of chlorine used, not in terms of the
amount of product produced. Therefore, greater chlorine use resulted
in more chlorine emissions and water pollutants. These pollutants
accounted for a large percentage of the impacts from System A4.
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SECTION II
INTRODUCTION
In recent years, the American public has become increasingly
aware that it can no longer continue to be a throwaway society.
The fact that our natural resources are limited has caused
widespread interest in recycling of post consumer solid wastes.
Although recycling of solid wastes has been practiced in varying
degrees throughout man's history, it is only recently that attempts
have been made to make recycling a national policy. However, before
recycling can be accepted as a national goal, it must be determined
if recycling actually benefits society.
Previous studies have only looked at parts of the total problem.
For example, they have only looked at savings in raw materials or
the removal of solid wastes from the environment. They have not
looked at the total picture. Our basic concept, however, is to use
a total systems approach to analyze the environmental impacts of
producing selected products utilizing virgin materials and various
amounts of recycled ferrous metals and aluminum. Determinations
are made of the material, water, and energy requirements of all
stages of virgin and waste materials acquisition, transportation,
and processing. Also determined are the outputs at each stage
including solid, airborne, and waterborne wastes that are generated,
assuming EPA Air Standards for FY 1975 and Water Standards for
FY 1977. The virgin and waste materials system are analyzed up to
the processing point at which materials are comparable.
The environmental impacts are examined for cases in which the
selected products are made solely from virgin materials and from
various amounts of virgin and waste materials. Consideration is
given to air and water pollutants, solid wastes, and the amounts of
material, energy, and water consumed. Estimates are made of the dollar
costs of controlling the environmental impacts.
The specific products considered in this study are carbon steel
manufactured from either virgin and scrap materials in the Basic
Oxygen Furnace (EOF) or scrap materials in an Electric Furnace
and cast and wrought aluminum manufactured from either virgin
materials by primary smelters using the Bayer-Hall Process or from
scrap aluminum by secondary smelters.
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Carbon steel was chosen for study because it comprises about 90 percent
of the total steel produced.( ) Although a large variety of different
grade carbon steels with varying amounts of carbon and silicon are pro-
duced as basic materials, the overall processes involved in their manu-
facture are quite similar. Basic steelmaking from scrap and pig iron
can be achieved in four types of steel furnaces: (1) Bessemer, (2)
Open Hearth, (3) EOF, and (4) Electric Furnace. However, the EOF and
electric furnace were selected for study because trends in steel pro-
duction show sharp rises in production volumes by the EOF and electric
furnace, with decreasing production volumes from the Bessemer and Open
Hearth Furnaces(2), indicating future steel making will be in BOF and
Electric Furnaces.
Wrought and cast aluminum products are both considered in this
study because the specifications for the two aluminum types are
quite different. Primary smelters produce mainly wrought products
with some cast products while secondary aluminum smelters primarily
produce cast products. The Bayer-Hall Process is studied for
primary aluminum production because it accounted for all the
primary aluminum produced in the U. S. in 1973. Secondary aluminum
smelters were selected for recycled aluminum production because ,-,.,
they account for most of the aluminum produced from scrap materials.
The sources of scrap materials chosen for this study are obsolete
steel and aluminum cans and junk autos. They were chosen because
of their volume and impact on the environment. In 1971, 71.3
billion steel cans, consuming 6.5 million metric tons of steel
were produced in the U. S.C^iS) This figure accounts for about
four percent of the municipal solid waste collected. Only four to
five percent of these cans were recycled in 1971.(6) From 1961 to
1971, aluminum containers and packaging had an annual growth rate
of 15.7 percent. They accounted for 14.6 percent of all aluminum
shipments in 1971PJ Nine billion aluminum cans were produced in
1971 resulting in 410 thousand metric tons of MSW.(3) Recycling
centers collected 11.6% of aluminum cans produced in 1971, 16.3%
in 1972 and 20% in 1973.(7'
Annual discard of vehicles approached 8 million units in 1968.
Based on current trends, the number scrapped annually is expected
to climb to 10.4 million units by 1975, 11.6 million by 1980, and
13.2 million by 1985. Autos account for about 85 percent of the .
total, with trucks and buses accounting for the remaining 15 percent. *
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Presently, about one-fourth of the recycled steel scrap is
from discarded automobiles. However, the availability of
scrapped autos exceeds the demand for them. It is estimated
that a backlog of some 12-20 million auto hulks exists with an
additional 0.9 million being abandoned each year.™)
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SECTION III
STUDY APPROACH AND METHODOLOGY
There are two broad classes of environmental impacts which can
be discerned and discussed—quantifiable impacts, and those of a
more subjective, qualitative nature. The former category includes
those impacts which can be measured, such as kilocalories of energy
and kilograms of air pollutants for various manufacturing processes.
The latter category includes impacts for which hard data do not
exist. For example, it is impossible to assign precise numerical
measures of aesthetic blight caused by mining activities. For other
cases, data may exist; but it might be of poor quality, examples
being the relative environmental damage of solid waste disposal of
various products, or the relative environmental damage of various air
pollutants or of various water pollutants. This study is confined
to the determination of the quantitative impacts only. Qualitative
aspects, although referred to from time to time in this study, are
not part of this analysis.
Basic Approach
Modules
The effort expended in this study went into determining the
quantifiable impacts of manufacture. The term "manufacture" is
used throughout this report in a general sense--it includes those
activities associated with materials from the time they are severed
from the earth or recovered from the solid waste stream to the point
where the finished product has been produced. Also included are all
transportation links in the processing sequence. The manufacturing
activities which intervene are designated processes or subprocesses.
The data obtained for each process or subprocess are presented in a
module summary. The module summary presents the data for basic
materials, water and energy consumptions for both the process and
the transportation of the product to the next process. Also shown
in the module summary are the on-site air emissions, water effluents
and solid wastes for the process as well as the off-site environmental
impacts which result from the production of energy consumed in the
process and the transportation of the product from that process to
the next process. Figure 1 summarizes the data which are presented
in each module.
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E W T
•J/ >U >L
Materials
Acquisition
^ >K v >4^ >!/•
AE WE SW TI El
E W
Jx Jx
Materials
Processing
AE WE SW
I
El
Final
Product
Inputs
E = Energy (in all forms)
M = Materials
W = Water
T = Transportation to Next Process
(includes all modes)
Outputs
AE = Atmospheric Emissions
WE = Water Effluent
SW = Solid Wastes
TI = Transportation Impacts
El = Energy Impacts
FIGURE 1. SUMMARY OF DATA PRESENTED IN EACH MODULE
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The on-site environmental impacts and off-site environmental
impacts from energy production and transportation are then totaled
and the total environmental impact of the process is presented
in terms of six basic impacts:
1. Material "inputs: The amounts and types of virgin raw materials
or scrap materials required for each operation were determined in
terms of a given product output. Materials not intended to become
part of the finished product, such as cooling water and fuels, were
excluded from raw materials. The materials used are totaled indi-
vidually, and no attempt was made to compare the various virgin
materials based on availability or scarcity. The most widely acknow-
ledged projections of this type have been made by the Bureau of Mines.
However, questions have been raised about the validity of these pro-
jections because of the assumptions on which they are based.
2. Energy: The energy used by each operation, including transportation,
for a given product output was reported. Process energy used by the
actual manufacturing operations was considered. That used for space
heating of buildings and other miscellaneous categories was excluded
wherever possible. The second-order energy necessary to extract,
process and transport fuels are included as well as the heating value
of the specific fuels used in a system.
3. Water Discharged: The volume of water discharged to the natural
bodies of water per unit of product output from each process is reported.
Also reported separately in this category is mine diainage, that is,
water which must be pumped from a mine site to continue the operation.
This impact category considers water use only, not what is discharged
from a process into the water in the form of pollutants. (This factor
is covered separately.)
4. Solid Wastes: The volume of solid waste per unit of product
output which must be landfilled, or disposed of in some other way,
was determined also. Three types were measured: process wastes,
post consumer wastes, and overburden from mining. The first type
process wastes, includes wastewater treatment sludges, solids
resulting from air pollution control, trim and waste materials from
manufacturing operations and fuel combustion residues generated by
coal combustion. Post consumer solid wastes are junk autos and scrap
which are removed from the solid waste stream by the resource recovery
modules. Mining overburden is the material removed to expose ore bodies.
5. Atmospheric Endssions: This category includes only those
emissions (expressed in kilograms per unit of product output) generally
considered to be pollutants. Ten identifiable pollutants were considered
11
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for each operation--particulates, nitrogen oxides, hydrocarbons,
sulfur oxides, carbon monoxide, aldehydes, other organics, chlorides,
fluorides and ammonia. The amounts reported represent actual
discharges into the atmosphere after emission controls meeting 1975
Air Standards have been applied. If no standards presently exist
for the operation, a level of control which was judged to be the
best practical technology was assumed. All such atmospheric
emissions were treated as being of equal weight, and no attempt was
made to determine the relative environmental damage of each of these
pollutants. However, we do note that there are differences in the
relative harm caused by air pollutants. There is not sufficient
documentation available to weight them with respect to each other
now.
6. Waterborne Wastes: This category includes the water pollutants
from each operation expressed in kilograms per unit product output.
These are effluents after wastewater treatment meeting 1977 Water
Standards have been applied and represent discharges into receiving
waters. As with air emissions, if no standards current exist
for the process, a level of control which was judged to be the best
practical technology was assumed. Fifteen specific pollutants are
included--BOD, COD, suspended solids, dissolved solids, oil and grease,
fluorides, chlorides, phenol, sulfides, iron, ammonia, cadmium, lead,
manganese, and cyanide. Other factors such as turbidity and heat,
were not included because there was no acceptable way to quantify
them.
Synthesis Methodology
The general approach used to carry out the calculations for the
quantitative comparison was straightforward. All processes and
subprocesses were first considered to be separate, independent
systems and data were reported in the modules. For each system, a
standard unit such as 1,000 kilograms of output was used as a basis
for calculations. A complete materials balance was first determined.
If marketable co-products or by-products were produced, the materials
inputs were adjusted to reflect only the input attributable to the
output product of interest.
Once the detailed impact information had been determined for 1,000
kilograms or 1 metric ton of output from each module, a master flow
chart was established for the manufacture of a product. Using known
yield data, the kilograms of output of each module necessary to
12
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produce 1,000 kilograms or 1 metric ton of a finished product
were determined. Summary tables of impacts for the manufacture
of 1,000 kilograms or 1 metric ton of a product were then
constructed. Transportation steps or energy inputs were not
shown on the master flow charts because they had previously been
incorporated in the individual modules.
After the impacts for each system were determined, it was then
possible to compare the systems using virgin materials with the
systems using recycled materials. Comparisons were made on the
basis of 1) materials 2) energy 3) water use 4) air emissions
5) water effluents, and 6) solid wastes.
Environmental Cost Estimates
An assumption basic to this study was that 1975 Air Standards and
1977 Water Standards would be met. Air emissions and water effluents
were reported with this premise in mind. However, there is a real
dollar cost to industry in meeting these standards. When sufficient
data were available, cost estimates for meeting the standards were
developed for each module and reported as dollars per metric ton of
product. Costs for the total system were developed by weighting the
environmental costs for the individual modules by the number of
kilograms of output from that module which were required to produce
a metric ton of finished product for the system. Although the total
costs of controlling the environmental impacts could not be determined
for each system, care was taken to see that the cost data were
comparable for all systems.
Assumptions
An important part of any study concerns the assumptions that must
be made since some assumptions are always necessary to limit a study
to reasonable scope. It is important for the reader to know what
assumptions have been made in order for him to understand fully the
scope and applicability of the study.
In the course of this research, the following assumptions were made:
1. Data Sources: An attempt was made in every case to obtain
data which were "typical" and which could be verified in the open
literature. Extensive use was made of government agencies and
publications, technical associations and open literature sources.
13
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National average data were used where possible. Certain sets of
data involved proprietary processes so that information was
submitted to us on a confidential basis. However, data in the
public domain were used whenever possible.
2. Sources of Raw Materials: Although iron ore and bauxite are
both imported to the U. S., all raw materials were considered to
originate in the U. S.
3. Secondary Impacts: Secondary impacts resulting from extraction,
processing and transporting fuels were considered as well as the
primary impacts of the fuels themselves. Secondary impacts resulting
from effects such as manufacturing the equipment used in mining and
processing are small per unit output, and can be excluded without
significant error.
4. Small Amounts of Materials: The impacts associated with materials
which aggregate to 5 percent or less by weight of the container
were not included. The list of materials which comprise the "less than
5 percent" category was examined to insure that no known "high
environmental impact" materials were included. This inspection insures
that the values from this assumption do not lead to an error of greater
than 5 percent in the final results.
5. Electricity: Electrical energy is considered from the point of
view of its impact on the total energy resources of the nation. A
national average energy expenditure of 2,977 kilocalories of fossil
fuels is required for each kilowatt-hour of electricity made
available to the public. Hence, this conversion factor is used rather
than the direct use conversion factor of 860 kilocalories per kilowatt-
hour. The impacts from mining or extraction of these fuels were
included in the analysis.
6. Resource Recovery: When a resource recovery operation processes
twenty metric tons of solid waste to recover 1 metric ton of cans,
the solid wastes for the operation are: Post consumer solid wastes =
20 metric tons, Processing wastes = 19 metric tons. The net effect
is the removal of 1 metric ton of solid waste from the environment.
Limitations
A basic hindrance to a study of this type is that many industrial
plants do not keep records in sufficient detail to determine the
data in the desired form. For instance, if energy data are needed
14
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for a specific subprocess in a plant, that information may not
be available. The plant may have data only for several combined
processes. In this event, prorations must be made to the particular
processes of interest.
Another problem is that many of the resource recovery processes
are in the experimental or pilot plant stage, especially aluminum
recovery from municipal solid waste. Energy requirements may be
known within 50%, but no data exist on air emissions or water
effluents. Therefore, it was necessary to use engineering calculations
of materials balances for processes in some instances where actual
operating data are not available.
IS
-------
SECTION IV
AUXILIARY MODULES
Introduction
Energy and transportation are common inputs for most modules in
the steel and aluminum systems. The systems which use recycled
materials also require resource recovery modules as sources of
steel and aluminum scrap. This section describes these auxiliary
processes and their associated environmental impacts. The sources
of energy given consideration in this study are coal, petroleum,
natural gas and electricity. In addition, the emissions which result
from the on-site combustion of fossil fuels are described here.
The modes of transportation considered are rail, truck, water and
pipeline. The resource recovery modules include municipal solid
waste recovery, separated can recovery, detinnning, auto hulk
processing and auto scrap processing by shredding or baling and
incineration.
Energy
The environmental impacts resulting from the extraction, processing
and transportation of coal, petroleum and natural gas are described
here as well as the emissions which result from the combustion of
these fuels by stationary sources. Finally, the production of
electricity and its resulting environmental impacts are discussed.
Coal Mining and Processing
Open pit and underground operations each account for half of the
coal mined in the U. S. Since 80% of a coal deposit can be recovered
by open pit operations as opposed to 50% by underground methods,
open pit mining operations are becoming more prevalent every year.
Coal is usually cleaned or processed before use. The primary
purpose of a preparation plant is to crush the coal, remove impurities
and classify the product into standard size. Approximately 20% of
the raw coal processed in a cleaning plant is rejected as refuse.
Acid mine drainage and overburden are the principal impacts resulting
from coal mining. However, EPA effluent guidelines for the coal
mining industry^*2) have set the following schedules for coal processing
17
-------
plants, underground mine drainage and surface mine drainage:
suspended solids 30 mg/1
pH 6.0-9.0
total iron 4.0 mg/1
alkalinity greater than acidity
toxic materials none
oil and grease 5.0 mg/1
These figures and the water use figures shown in Table 1 were used
to calculate the water effluents shown in the table. The dissolved
solids figure in the table is based on an average of 3000 mg/1 of
dissolved solids in the discharge of a mining operation.'2°J The
recommended water pollution control procedure is neutralization to
a pH of 6.0 to 9.0 accomplished by the use of lime, limestone,
oxidation or varied combinations of the three.
It can also be seen from Table 1 that the amount of overburden resulting
from coal mining is 8.34 MT/MT of coal. This figure is based on the
fact that the average coal production per acre from strip mining is
6,661 metric tons,^4) and the average depth of overburden {specific
gravity of 1.5) removed by the operation is 18.3 meters;^"J yielding
16.68 MT of overburden per MT of coal. However, only 50% of coal
production is by strip mining and the volume of overburden extracted
during underground operations is negligible in comparison with that
removed during surface mining. Hence, the average weight of overburden
removed per ton of coal extracted is only half that value removed
during stripping alone.
Air emissions result primarily from fuels burned on site and dusts
from coal cleaning operations which contribute 1.55 kg of dust for
each ton of coal mined.
Crude Petroleum Extraction
More than 80 percent of modern wells are drilled by the rotary
process. In this process, a bit is turned at the bottom of the
hole and drilling mud is pumped through the drill pipe to cool the
bit and flush drill cuttings to the surface. After drilling to an
intrusion area, the hole is protected by inserting a casing. Upon
completion of the well construction, production can begin. Oil wells
produce primarily under four mechanisms: gas expansion, gascap drive,
water drive, and gravity drainage. Once production is started, the
products are transported mainly by pipeline to oil field tank
batteries or refinery storage vessels. Preliminary treatment involves
separation of hydrocarbons from brine and settleable solids. The
hydrocarbons are then processed by a gas plant or refinery.
18
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TABLE 1. ENVIRONMENTAL IMPACT
TRANSPORTATION
Basis: 1 metric ton of coal
RESULTING
Coal Mining
WATER DISCHARGED (liters) :
Process
Mine Drainage
AIR EMISSIONS (grams) :
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams) :
Suspended Solids
Dissolved Solids
Oil and Grease
Iron
SOLID WASTES (kilograms) :
Overburden
Processing Waste
ENERGY CONSUMPTION --
(kilocalories)
150
310
1689
148
33
8
54
1.5
0.1
14
1380
2
2
8340
190
83,500
FROM COAL MINING AND
Transportation Total Sources*
9
11
34 1723
35 183
47 80
43 51
64 118
3.4 5
3.7 4
10, 12
14
1380
2
2
13
8340
190
50,900 134,400 16
TRANSPORTATION (metric ton kilometers):
Rail
Water
315
55
*
For sources, see references beginning on page 111,
19
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The major pollutant sources in oil drilling production operations
are lost oils resulting from well blowouts, leaks and spills, and
produced brine. Approximately 2 liters of brine containing 100,000
mg/1 of dissolved solids are produced with each liter of crude oil> ^
These brines may be disposed of by evaporation or deep well injection.
If care is not exercised in selection of the subsurface formation,
contamination of ground water can result from deep well injection.
However, with proper precaution, deep well injection or evaporation are
environmentally adequate for brine disposal and result in no pollutants
being released to the environment.
The major emissions associated with crude petroleum extraction are
evaporated hydrocarbons from processing losses which amount to 1.4
kg per 1000 liters of crude oil extracted(19) and emissions resulting
from the combustion of fuels. Table 2 summarizes the environmental
impacts for the extraction of 1000 liters of crude petroluem.
TABLE 2. MODULE SUMMARY SHEET FOR CRUDE PETROLEUM EXTRACTION
Basis: 1000 liters of crude oil shipped
Source
WATER DISCHARGED (liters):
Process 610 17
AIR EMISSIONS (grams): 11,19
Particulates 526
Sulfur Oxides 4543
Carbon Monoxide 812
Hydrocarbons 1439
Nitrogen Oxides 208
Aldehydes 40
Organics 0.23
SOLID WASTES (kilograms): 20
Processing Waste 0.60
ENERGY CONSUMPTION (kilocalories): 471,100 16,21
TRANSPORTATION (metric ton kilometers) 17
Barge 89.9
Truck 32.1
Pipeline 353.1
20
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Petroleum Refining
An integrated petroleum refinery produces a large number of gasoline,
fuel oil and petrochemical products using various alternative processes
and feedstocks. It is extremely difficult to specify the quantity
of emissions, effluents and solid wastes attributable to the production
of specific output products since a number of products may evolve from
the same operation and alternative processes and feedstocks are used
to produce particular products.
Emissions and effluents from petroleum refineries have been typified
in accordance with the complexity of operations performed. The
American Petroleum Institute has categorized petroleum refineries
in five groups for which profiles of effluents have been described.
Their category C refinery performs topping and cracking and also
produces petrochemicals. Outputs consisting of gasoline, diesel and
residual fuel oil and petroleum coke are inputs to many processes in
this study. In this study no distinction is made between the effluents
and emissions which result from the different products. They are
only given for the refining of 1000 liters of liquid hydrocarbon fuels.
The emissions shown in Table 3 are from a new 100,000-barrel per day
capacity refinery with a 3 percent process loss assumed. The possible
sources of emissions include the sludge incinerator, catalytic
cracker, flare, boiler and process heaters, blowdown systems, process
drains, cooling towers, pipe valves and flanges, vessel relief valves,
pump and compressor seals and the tank farm.
The major sources of water pollutants from refinery operations are
storage tank drainoffs, crude desalting and distillation, and thermal
and catalytic cracking. Table 3 contains the summary data on
biologically treated effluents from a class C refinery as defined by
the API. Also shown in this table are the environmental impacts for
the overall system of supplying petroleum fuel which includes the
steps of extraction, transportation, and refining.
Natural Gas Production
Natural gas extraction operations may be associated with 1) "dry gas"
fields, 2) condensate natural gas liquid extraction, or 3) operations
associated with crude petroleum. Dry gas fields produce no liquids
and only require processing to remove water, hydrogen, sulfide and
carbon dioxide. Water is removed by cooling the gas to the dew
point with subsequent removal of the condensed water. Complete
dehydration usually requires the use of solid absorbents or hygroscopic
21
-------
TABLE 3. ENVIRONMENTAL IMPACT RESULTING FROM EXTRACTION,
TRANSPORTATION AND REFINING OF 1000 LITERS OF LIQUID
HYDROCARBON FUEL
Basis: 1000 liters of liquid petroleum fuels
Extraction Transportation Refining Tota- Source
WATER DISCHARGED (liters): 24
Process 630 7.8 638
AIR EMISSIONS (grams): 23
Particulates 54.2 37.9 13.2 105
Sulfur Oxides 467.9 7,3 257.1 732
Carbon Monoxide 83.6 465.5 214.5 764
Hydrocarbons 1482.6 112.2 287.1 1882
Nitrogen Oxides 215.0 462.0 273.7 951
Aldehydes 41.2 8.1 -- 44
Organics 0.2 3.3 -- 4
WATER POLLUTANTS (grams): 22
Suspended Solids 38 38
Dissolved Solids 2517 2517
BOD 99 99
COD 284 284
Oil and Grease 42 42
Phenols 6 6
Sulfide 6 6
Ammonia 10 10
SOLID WASTES (kilograms):
Processing Wastes 0,62 1
ENERGY CONSUMPTION .oc ,nn _. C1_ ,cc: ,Qn . 10, .nn _,
„ ., , . .. 485.200 75.510 655.690 1.196.400 24
(kilocalories) '
TRANSPORTATION (metric
ton-kilometers):
Barge 893.6
Truck 33
Pipeline 364
22
-------
liquids. Contact with various alkaline solutions is commonly used
to remove hydrogen sulfide and carbon dioxide.
A number of detailed processes may be used in the removal of liquified
natural gas. Most involve manipulation of working pressures and
temperatures to selectively extract out various fractions, followed
by refrigeration to liquify the desired gas.
Table 4 shows the environmental impacts which result from natural
gas production. Of prime concern is the large amount of carbon
monoxide, hydrocarbons and nitrogen oxides. The hydrocarbon emissions
result from process leaks to the atmosphere. The carbon monoxide and
nitrogen oxides primarily result from the use of natural gas to run
large compressor engines.
TABLE 4. ENVIRONMENTAL IMPACTS RESULTING FROM NATURAL GAS PRODUCTION
AND TRANSPORTATION
Basis: 1000 cu meters of natural gas
Extraction Transportation Total Source
WATER DISCHARGED (liters): 17
Process 2410 2410
AIR EMISSIONS (grams): 17
Particulates 128 19 147
Sulfur Oxides 385 15 400
Carbon Monoxide 8333 178 8,511
Hydrocarbons 22,596 69 22,665
Nitrogen Oxides 24,679 237 24,916
Aldehydes 3.0 3.0
Organics 4.3 4.3
ENERGY CONSUMPTION 390,540 52,520 443,060 16,21
(kilocalories)
TRANSPORTATION (metric
ton-kilometers) 17
Rail 100
Truck 33
Barge 33
Pipeline 166
23
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Fuel Combustion
Table 5 shows a set of atmospheric emission factors resulting
from the combustion of fossil fuels. The emissions for coal
combustion are those which result after control by multiple
cyclones or an electrostatic precipitator. The emissions for
fuel oil and natural gas combustion are those that result from a
well-operated source. These factors have been used throughout the
study to determine the on-site atmospheric emissions which result
from fuel combustion.
TABLE 5. EMISSION FACTORS FROM STATIONARY SOURCES
Pollutant Coal Coal Fuel Oil Fuel Oil Natural Natural
Industrial Utility Industrial Utility Gas Gas
Heat Heat (1000 (1000 Industrial Utility
(1 metric (1 metric liters) liters) (1000 m3) (1000 m )
ton) ton)
Particulates 12,000^ 2,750 290
Sulfur Oxides 38,000^ 28,880^ 10
Carbon
Monoxide 500 500 25 5 66
Hydrocarbons 150 150 350 250 640 640
Nitrogen Oxides 9 7,200 3,700
Aldehydes 3 3 120 120 48 48
Organics 112 64
(a) After control by multiple cyclones or an electrostatic precipitator
with an 85% efficiency.
(b) 2% sulfur coal.
(c) 1.5% sulfur fuel oil.
Source: Reference 11.
-------
Electricity Production
Table 6 shows the environmental impacts associated with electricity
production from fossil fuel fired plants in the U. S. Column 1 shows
the on-site impacts resulting from fuel combustion. Coal, fuel oil,
and natural gas are assumed to provide 54.5, 17.0, and 28.5 percent,
respectively of the energy requirements.(25j The emissions shown in
Column 1 are after 1975 Standards for New Sources(26) are met for
particulates, sulfur oxides and nitrogen oxides. The quantities
shown for carbon monoxide, hydrocarbons, aldehydes and organics were
obtained using the values for power plants in Table 5. The offsite
impacts are those which result from the extraction, processing and
transportation of the required coal, fuel oil and natural gas. Of
particular interest in this column are the impacts resulting from
coal usage in the form of solid wastes.
Transmission losses are assumed to be 5%. On site and off site impacts
were multiplied by this figure to determine the impact of electricity
transmission. Of particular interest is the total energy used
(2,977,000 kilocalories)in the production of 1000 kw-hr of electricity
which has a fuel equivalent of 860,000 kilocalories. This use represents
an overall efficiency of 29% in electricity production.
Transportation
Environmental impacts occur when goods are transported because of
the consumption of fossil fuels to provide necessary energy. In this
study, the modes of transportation included are rail, truck, pipeline
and water. These impacts were calculated by determining the kinds and
amounts of fuels used by each mode on a national average basis. Impacts
were then calculated for 1,000 metric ton-kilometers.
Rail
(27)
The latest complete set of fuel consumption datav ' indicates that
diesel fuel accounted for 98 percent of the energy expended by railroads
in 1968. We assumed that 100 percent of the energy was supplied by
diesel fuel and that 1.42 X 10* 4 kilocalories of fuel were used. This
fuel use resulted in 11.21 X 10** metric ton-kilometers of transportation.
The corresponding fuel consumption was 13.64 liters per 1,000 metric
ton-kilometers. This value was combined with information in Table 7
to yield the impacts presented in Table 8.
25
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TABLE: b. ENVIRONMENTAL IMPACTS OF ELECTRICITY PRODUCTION
Basis: 1000 kw-hr = 860,000 kcal
On-Site Off-Site Transmission3 Total Source
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
BOD
COD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
SOLID WASTES (kilograms)
Overburden
Processing Waste
ENERGY CONSUMPTION
Coal (kg)
Equivalent kcal
Oil (,£)
Equivalent kcal
Natural Gas (m3)
Equivalent kcal
Total kilocalories
330
38
218
1,482,400
45.9
459,000
28.5
772,777
2,714,100
261
67
393
1,818
42
120,800
13
3
36
4.8
416
4.5
13.0
2.4
0.5
0.3
0.3
0.5
0.2
21
0.2
0.7
0.1
0.0
0.0
0.0
0.0
91
4
274
70
759
11,26
3,960
110
100
2,430
10.2
0.5
106
755
1,972
2,127
3.3
1.4
203
43
104
228
0.7
0.1
4,269
908
2,176
4,785
14.2
2.0
5
437
5
14
3
0.5
0.3
0.3
0.5
1,909
84
141,700 2,977,000
(a) A transmission loss of 5 percent was assumed. On site and off site
impacts were multiplied by this figure to determine the impact of
electricity transmission.
25
26
-------
N>
TABLE
ATMOSPHERIC EMISSIONS
(grams)
Particulates
Nitrogen Oxide
Hydrocarbons
Sulfur Oxides
Carbon Monoxide
Aldehydes
Organics
ENERGY (kilocalories)
7. EMISSIONS FROM FUEL COMBUSTION BY MOBILE SOURCES
Gasoline
(one liter)
1.2
21.2
35.4
0.7
150.4
1.4
5.3
8,200
Diesel Locomotive
(one liter)
3
9.0
6.0
7.8
8.4
0.48
0.84
9,350
Diesel
(one liter)
1.56
44.4
4.44
3.24
27.0
0.36
0.36
9,350
Fuel Oil
Mobil
Source
(one liter)
24.0
18.0
18.0
18.0
6.0
1.3
—
10,000
Natural Gas
Interval
Combustion
(one m^)
76.9
12.8
25.6
9,350
Source: Reference 11
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TABLE 8. FUEL CONSUMPTION AND ENVIRONMENTAL IMPACTS RESULTING FROM 1000 METRIC TON'KILOMETERS
OF TRANSPORTATION BY EACH MODE
Rail
Truck
Water
Pipeline
FUELS
Gasoline - liters
Diesel - liters
Fuel Oil - liters
Natural Gas - m
ENERGY kilocalories
13.64
128,000
15.9
28.6
397,000
3.64
15.86
193,000
13.1
122,000
ro
CD
ATMOSPHERIC EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Other Organics
41
106
115
82
123
6.6
11.5
64
104
3,164
690
1,607
32.6
94.6
386
40
194
302
447
21.6
1.3
335
168
1,007
-------
Truck
g
In 1967, a total of 14.95 X 10 kilometers were traveled by trucks
engaged in intercity highway hauling. This resulted in 1.61 X
metric ton-kilometers of transportation. C28) It is estimated that
35 percent of this distance was traveled by gasoline engine trucks
while 65 percent was traveled by diesel fueled trucks. (29) National
average fuel mileage data are not available, but a reasonable
assumption based on actual experience is that this type of truck
travel results in fuel consumption rates of about 2.2 kilometers
per liter for either type of fuel. Thus, 24.6 X 108 liters of
gasoline and 4.54 X 1CP liters of diesel fuel were used in 1967.
From this, it was calculated that 15.4 liters of gasoline and 28.5
liters of diesel fuel were consumed per 1,000 metric ton-kilometers.
Using data in Table 7, impacts were calculated and are reported in
Table 8.
Water
During 1966, water traffic resulted in 7.3 X 10 metric ton-kilometers
of transportation.(30) Fuel consumption was 26.46 X 108 liters of
diesel fuel and 11.7 X 109 gallons of residual.(17) Therefore, 3.64
liters of diesel fuel and 15.86 liters of residual were consumed per
1,000 metric ton kilometers. Again, impacts were calculated and are
listed in Table 8.
Pipeline
Sources in the pipeline industry report that, on the average, about
0.85 cubic meters of natural gas fuel are required to transport 159
liters of oil 485 kilometers through a pipeline.(^) This requirement
translates to 0.85 cubic meters for 65.7 metric ton-kilometers, or
13 cubic meters of natural gas per 1000 metric ton-kilometer of crude
petroleum transportation. This factor, combined with information from
Table 7 enabled us to calculate the impacts for 1,000 metric ton-
kilometers of pipeline transportation. Pipeline transportation impacts
for moving other types of materials of interest in this study were assumed
to be approximately the same as for crude oil.
29
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Resource Recovery
The waste materials which are considered for recycling in this
study are ferrous and aluminum scrap from junk autos, and steel
and aluminum cans. Junk autos first go to the auto hulk processor,
where usable parts are stripped from the car and then to an auto
scrap processor where usable ferrous and aluminum scrap are produced
by shredding or baling and incineration. The cans may be recovered
from composite municipal solid waste or they may be collected
separately. After recovery, steel cans must go to a detinner before going
to a steel furnace. The following section describes the processes
necessary to make these materials available for recycling.
Auto Hulk Processing
Auto hulk preparation begins with the collection of individual
autos. After collection, the autos are stripped of their radiator,
battery, starter, wheels, gas tank, generator and other parts for
sale. The stripped auto is then crushed for transportation from
dismantler to the scrap processor. Approximately 80 percent of all
junk autos first go to an auto wrecker before going to a scrap
processor. Table 9 shows the environmental impacts associated
with auto hulk processing. The on-site impacts result from fuels
consumed for auto crushing. Other activities at the auto wrecker
are assumed to be connected with spare auto parts acquisition, which
would occur even if the hulks were not sold for scrap. It should be
noted that the auto hulk processor removes 1,532 kilograms (weight
of an auto) of solid waste from the environment, 1,378 kilograms ,,,,
of which are iron and steel and 23 kilograms of which are aluminum.
Any wastes which result from dismantling the auto are assumed to come
from the scrap processor.
Auto Scrap Processing
Auto scrap processors use balers, shredders and shears to produce
ferrous and aluminum scrap. For urban centers that discard at least
40,000 autos per year, the preferred method is shredding.(33) in
this procedure, huge hammer mills shred automobiles stripped of
radiator, battery, and motor into fist-size chunks which are passed
over a magnetic separator to clean steel from non-magnetic materials,
Aluminum can either be hand picked or separated from other metallies
by dense media separation.
30
-------
TABLE 9. SUMMARY SHEET FOR AUTO HULK PROCESSING
Basis: 1 auto hulk
On-Site Off-Site Transportation Total Sources
AIR EMISSIONS (grams) 11
Particulates 5 11 16
Sulfur Oxides 6 3 17 26
Carbon Monoxide 1000 3 525 1528
Hydrocarbons 210 7 114 331
Nitrogen Oxides 120 4 267 391
Aldehydes 4 59
Organics 2 16 18
SOLID WASTES (kilograms) 31
Post-consumer
wastes -1532 -1532
ENERGY CONSUMPTION 32
Liquid Hydrocarbon
fuels (/) 3.75
Equivalent kcal 32,100 4,500
Total Kilocalories 32,100 4,500 65,900 102,500
TRANSPORTATION (metric 2
ton kilometers)
Truck 166
31
-------
For areas that do not discard enough cars to support a shredder,
a combination of incineration, hand-tool dismantling and baling
or shearing can be used. In the baling operation, the hulk is
stripped, either by hand or incineration, and then compressed into
a cube.
Table 10 shows the environmental impacts which result from the
production of scrap metal by shredding. Published data for air ..__.
emissions and water effluents does not exist. Shredder manufacturers'- '
claim that the installations are equipped with the appropriate dust
control equipment and water, when used, is recycled. The on-site
emissions shown in Table 10 are from the consumption of liquid
hydrocarbon fuels.
Table 11 summarizes the environmental impacts for scrap metal
production using a smokeless incinerator and an auto baler. The
on-site impacts are emissions from the incinerator which is equipped
with an afterburner.C34) The energy consumption of this system is
higher than for the shredding system because of the fuels used for
incineration. Incineration also results in the release of more
atmospheric emissions than shredding but less solid waste. In
both systems, the water pollutants result from the use of electricity
which is partially produced through the use of coal.
Municipal Solid Waste Recovery
The municipal solid waste recovery system considered in this module
is one which produces the outputs shown in Table 12.
TABLE 12. OUTPUTS PER METRIC TON OF WET MUNICIPAL SOLID WASTE
PROCESSED
Material Kilograms
Baled Paper 50
Light Combustibles 670
Ferrous Metals 75
Aluminum 5
Usable Products (Total) 800
Land Fill 200
Source: References 42, 43 and 45.
32
-------
TABLE 10. SUMMARY SHEET FOR AUTO SCRAP PROCESSING BY A SHREDDER
Basis:1 metric ton of steel or aluminum scrap
On-Site Off-Site Transportation Total Sources
MATERIAL INPUTS
Auto Hulk (No.) 0.71
WATER DISCHARGED
(liters)
Process Water
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
.Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS
(grams)
Dissolved Solids
SOLID WASTES (kilograms)
Overburden
Processing Waste 94
ENERGY CONSUMPTION
Liquid Hydrocarbon
fuels ( JL} 1.8
Equivalent kcal 16,900
Electricity (kw-hrs)33.4
Equivalent kcal 99,400
Total kcal 116.3
(thousands)
TRANSPORTATION (metric-ton kilometers)
14
64
3
2,200
2.2
Rail
Truck
340
145
101.1
0.71
5
52
1
13
9
2
25
144
31
76
162
23
51
498
128
275
7
18
9
2
53
247
529
204
438
20
18
14
64
97
31
11
2, 11
35
219.6
36
33
-------
TABLE 11. SUMMARY SHEET FOR AUTO SCRAP PROCESSING BY HAND STRIPPING
AND A SMOKELESS INCINERATOR
Basis: 1 metric ton of steel or aluminum scrap
On-site Off-site Transportation Total Source
MATERIAL INPUTS 31
Auto Hulk (NO) 0.71 0.71
WATER DISCHARGED (liters)
Process Water 43 43
Mine Drainage 2 2
AIR EMISSIONS (grams) 11
Particulates 490 23 23 536
Sulfur Oxides 124 51 175
Carbon Monoxide 141 498 639
Hydrocarbons 8 438 128 564
Nitrogen Oxides 55 275 330
Aldehydes 23 7 30
Organics 131 18 149
WATER POLLUTANTS (grams)
Dissolved Solids 32 32
SOLID WASTES (kilograms) 2,11
Overburden 50 50
Processing 14 2 16
ENERGY CONSUMPTION 31
Liquid Hydrocarbon
fuels (J^) 8.34
Equivalent kcal 78,000
Natural Gas (m ) 13.05
Equivalent kcal 122,000
Electricity (kw-hr) 26.4
Equivalent kcal 78,600
Total kilocalories 278.6 15.8 101.1 395.5
(thousands)
TRANSPORTATION (metric 36
ton-kilometers)
Rail 340
Truck 145
34
-------
This system has the capacity to process 1000 tons per day of MSW
from residential and commercial sources. The unit processes in the
system consist of handpicking and baling of the paper fraction and
shredding the remaining waste. The shredded refuse is air classified
to separate the light combustibles, which are compacted and used as
fuel. The heavy materials from the air classifier are magnetically
separated twice to remove the ferrous materials. This part of the
system requires motors with a total of 2800 horsepower, which operate
9 hours per day at 60% of their rated current capacity.C42) The
energy requirements of this part of the system are shared equally on a
weight basis by the baled paper, light combustible, ferrous metal and
aluminum products.
Aluminum is separated from the materials which remain after magnetic
separation (20.5% of the original waste stream) by an aluminum magnet
which draws 40 kilowatts of electricity for 10 hours. (42) ^H of this
energy is allotted to the aluminum. The material remaining after
aluminum separation is then landfilled.
Table 13 shows the environmental impacts which result from the recovery
of one metric ton of ferrous scrap. It can be seen from this table
that the only on-site impacts are particulate emissions and solid wastes.
Approximately 2 kilograms of dust result from the shredding and handling
of one metric ton of MSW. However, it is assumed that bag filters
with a 90% efficiency will be used to control this dust. The on-site
processing waste shown in Table 13 results from the production of 250
kilograms of material which must be land filled for each metric ton
of output products. The transportation requirements are assumed to
be the same as those for ferrous scrap from auto scrap processors
since the distribution of junk autos and municipal solid waste both
vary with population.
Table 14 summarizes the environmental impacts which result from the
recovery of one metric ton of aluminum scrap. It can be seen from
this table that 108.7 kw-hr of electricity are required to recover
one metric ton of aluminum scrap as compared to 19.8 kw-hr of electricity
required to recover one metric ton of ferrous scrap. This higher
electricity consumption is due to the high power requirements of the
aluminum magnet and results in greater off-site impacts.
Separated Can Recovery
The can recovery systems considered in this module consist of
separate shredding operations to process steel and aluminum cans
which have been separated in the home and have been collected
separately. The cans are assumed to ride piggyback on the trucks
which collect the remaining municipal solid waste.
35
-------
TABLE 13. MODULE SUMMARY SHEET FOR FERROUS SCRAP RECOVERY FROM
MUNICIPAL SOLID WASTE
Basis: i metric ton scrap steel
On Site Off Site Transportation Total Source
MATERIAL INPUTS (kilograms)
Municipal Solid
Waste
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
1250
200
1250
15
85
18
43
95
23
51
498
128
275
7
18
238
136
516
171
370
7
18
42
44
SOLID WASTES (kilograms)
Overburden
Processing 250
Post-consumer -1250
38
2
38
252
-1250
42
ENERGY CONSUMPTION
Electricity (kw-hr) 19.8
Equivalent 58,900
kilocalories
Total kilocalories 58,900
101,100
160,000
42
TRANSPORTATION (metric-ton kilometers)
Rail
Truck
340
145
36
36
-------
TABLE 14. MODULE SUMMARY SHEET
MUNICIPAL SOLID WASTE
Basis: 1 metric ton of aluminum
On Site
MATERIAL INPUTS (kilograms)
Municipal Solid Waste 1250
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates 200
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
SOLID WASTES (kilograms)
Overburden
Processing 250
Post-consumer -1250
ENERGY CONSUMPTION
Electricity (kw-hr) 108.7
Equivalent kilo-
calories
Total kilocalories 324,200
TRANSPORTATION (metric -
ton kilometers)
Rail 340
Truck 145
FOR ALUMINUM SCRAP RECOVERY FROM
scrap
Off Site Transportation Total
1250
30 30
8 8
83 23 306
465 51 516
99 498 597
237 128 365
521 27 796
279
18 18
48 48
208 208
9 259
-1250
101,100 425,300
Source
42
44
42
42
36
37
-------
The unit processes necessary for steel scrap recovery are shredding
followed by magnetic separation to remove the ferrous from organic
materials which would accompany the cans. The unit processes
necessary for aluminum scrap recovery are magnetic separation to
remove unwanted steel cans and shredding of the remaining aluminum
cans.
Table 15 shows the environmental impacts which result from processing
separated aluminum cans. The energy requirements shown were obtained
from operating data for Alcoa's can recovery centers.(46) Transportation
requirements are assumed to be the same as for ferrous scrap. The
only on-site impact is the removal of one metric ton of post-consumer
solid waste from the environment.
Table 16 shows the environmental impacts which result from processing
separated steel cans. The energy requirement of 34.3 kw-hr of elec-
tricity was obtained by dividing the energy requirement for processing
aluminum cans by 2.42 which is the ratio of the weight of a steel can
to the weight of an aluminum can. Therefore, it was assumed that the
energy requirement for processing cans depends on the number of cans
which must be processed.
Detinning
The alkaline chemical process is used by nearly all modern large
installations for the detinning of tinplate. This process covers the
variations possible when a caustic solution containing an oxidizing
agent is used to remove both the tin and the underlying iron-tin
alloy from the steel. After washing, the steel is virtually free of
tin and the solution can be processed in several ways to yield
either pig tin or tin chemicals. Nearly all alkaline chemical
detinning is done with sodium hydroxide as the caustic and either
sodium nitrate, sodium nitrite, or a mixture as the oxidant. The
variations possible in pretreatment, number of detinning stages,
posttreatment, and recovery are numerous.(59) However, this module
is not concerned with tin recovery, and its environmental impacts
will not be considered.
Following detinning, scrap is put through as many as four rinses.
Rinse waters are advanced and used as solution makeup to conserve
chemicals and tin. The detinned scrap is compressed into large
bales weighing up to 270 kg or more using hydraulic presses if
the scrap is to be sold to steel mills.
38
-------
TABLE 15. MODULE SUMMARY SHEET
ALUMINUM CANS
Basis: 1 metric ton of aluminum
On site
MATERIAL INPUTS (kilograms)
Aluminum cans 1000
WATER DISCHARGE (liters)
Processing
Mine Drainage
AIR EMISSIONS (gms)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved solids
SOLID WASTES (kilograms)
Overburden
Processing
Post-consumer -1000
ENERGY CONSUMPTION
Electricity (kw-hr) 83
Equivalent kcal 247,100
Total kilocalories 247,100
TRANSPORTATION (metric- ton
kilometers)
Rail 340
Truck 145
FOR ALUMINUM SCRAP RECOVERY FROM
scrap
Off site Transportation Total
1000
23 23
6 6
63 23 86
354 51 405
75 498 573
181 128 309
397 275 672
1 78
18 18
36 36
158 158
7 7
-1000
101,100 348,200
Source
46
36
39
-------
TABLE 16. MODULE SUMMARY SHEET FOR
CANS
Basis : 1 metric ton of ferrous scrap
On Site Off
MATERIAL INPUTS (kilograms)
Steel Cans 1000
WATER DISCHARGED (liters)
Process 9
Mine Drainage 2
AIR EMISSIONS (grams)
Particulates 26
Sulfur Oxides 146
Carbon Monoxide 31
Hydrocarbons 75
Nitrogen Oxides 164
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids 15
SOLID WASTES (kilograms)
Overburden
Process
Post -consumer -1000
ENERGY CONSUMPTION
Electricity (kw-hr) 34.3
Equivalent (kcal) 102,100
Total kilocalories 102,100
TRANSPORTATION (metric-
ton kilometers)
Rail 340
Truck 145
FERROUS SCRAP RECOVERY FROM STEEL
Site Transportation Total Source
1000
9
2
23 49
51 197
498 529
128 203
275 439
7 7
18 18
15
65 65
3 3
-1000
46
101,100 203,000
36
40
-------
The use of aluminum ends on 3teel cans presents a problem to detinners
The aluminum residual totalling 5 percent by weight reacts violently
in the detinning solution and causes considerable loss of caustic
values without any suitable recovery. The aluminum consumes an
amount of caustic equal to one and one half times its weight and an
amount of sodium nitrate equal to twice its weight.(38) With alumim n
present, a two stage detinning operation is necessary to keep sodium
nitrate consumption to a minimum. From Table 17, it can be seen that
95 kg of sodium hydroxide and 7.6 kg of sodium nitrate are consumed
for every metric ton of detinned scrap produced. It can also be seen
from this table that the only on-site environmental impact resulting
from detinning is 160 kg of solid waste. This waste is NaA102 which
is an endproduct of the aluminum and caustic reaction.
Other than a small amount of ammonia given off during the reduction
of sodium nitrate, there are no process emissions or effluents
produced at a modern detinning plant. Spent caustic is a byproduct
which is sold for regeneration. The residue which results from
delacquering is dewatered and sold to tin smelters for recovery of
tin values. Water used for rinsing the detinned steel is recycled
within the plant to prevent the loss of chemicals.(38) The on-site
air emissions shown in Table 17 result from fuel combustion.
An assumption basic to this module is that when sufficient steel cans
are recovered from solid wastes to necessitate detinning because of
a potential build up of tin in the steel product, new detinning
plants will be built either at the resource recovery center or near
the steel plant.(41) Therefore, no additional transportation will be
necessary for scrap steel cans on their way to the steel mill. This
view is supported by the detinning industry, for there are only
14 detinning plants presently in operation in the U. S. New plants
would have to be built if steel cans were to be recovered on a large
scale.
41
-------
TABLE 17. MODULE SUMMARY SHEET
Basis: 1 metric ton of tin free
MATERIAL INPUTS (kilograms)
Scrap Cans
Sodium Hydroxide
Sodium Nitrate
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
SOLID WASTES (kilograms)
Overburden
Processing
ENERGY CONSUMPTION
Coal (kg)
Equivalent kcal
Liquid Petroleum Fuel (/)
Equivalent kcal
Natural Gas (m )
Equivalent kcal
Electricity (kw-hr)
Equivalent kcal
Total kilocalories
FOR DETINNING
scrap
On Site Off Site
1060
95.4
7.6
21
3
84 26
400 107
2 55
5 143
84 200
1
41
81
160 3
4.56
31,000
9.94
92,900
3.32
31,000
22.5
67,000
221,900 14,100
Total Source
1060 38
95.4 38
7.6 39,40
21
3
11
110
507
57
148
284
1
41
38
81
163
38
236,000
42
-------
SECTION V
STEEL
Steel From Virgin Materials
This section describes the operations necessary to produce steel from
virgin materials. Figure 2 shows the arrangement of processes necessary
for steel production. Iron ore is reduced to metallic iron in the blast
furnace. Limestone and other fluxes are used to form a slag to remove
impurities from the iron, while coke acts as a source of fuel and car-
bon monoxide which reduces the iron ore. Coking operations and the
necessary coal input are not shown in the figure because the coking
operations are discussed in the blast furnace module and the coal is
handled as a fuel input. The molten iron from the blast furnace is
refined into steel in the Basic Oxygen Furnace where oxygen chemically
unites with the impurities which are burned out.
Iron Ore Mining
Iron ore is the basic raw material for steel production. Over 90% of
the iron ore is presently extracted by open pit surface mining tech-
niques with the remainder being recovered from deep vertical shaft
mines. Production is concentrated in the North Central states with
over 60% of the total amount originating in Minnesota.
Iron ore is beneficiated to enhance either its chemical or physical
characteristics to make a more desirable feed for the blast furnace.
The ore is crushed and screened to reduce crude ore in size to eliminate
handling problems and to increase heat transfer. Blending of the ore
produces a more uniform product. Concentrating processes, such as
washing, jigging, magnetic separation, heavy mineral separation or
flotation, remove unwanted sand, clay or rock from crushed or screened
ore. Agglomerating processes, such as sintering, follow concentration
operations and serve to increase permeability of furnace feed and
reduce "fines" which normally would be lost in the flue gases. The
agglomeration procedure may take place at either the mine or the steel
mill.
The crushing and screening operations and materials handling operations
result in the generation of 73% of the onsite particulate emissions.
43
-------
Figure 2: Steel Production by the Basic Oxygen Furnace Using Virgin Materials
(current mix - 30% Home Scrap; 70% Pig Iron) System Fl
Home Scrap
333 59. lm3
Numbers are kilograms of material required to produce one metric ton of steel ingot.
Numbers in parenthesis are kilograms of material required to produce one metric ton of iron or lime.
-------
The remaining emissions result from the combustion of fossil fuels.
Table 18 summarizes the environmental impacts of iron ore mining.
It can be seen from the table that the dominant environmental effect
of mining iron ore is on-site mining wastes. These wastes are quite
sizable and amount to 3.6 metric tons per metric ton of marketable
ore.
Limestone Quarrying
Limestone is used as a flux in the blast furnace and is processed
into lime for use in steel making furnaces. Limestone is typically
mined quite close to the ultimate consumer which frequently dictates
that the mining operation be near, or even within, heavily populated
areas. Hence, their environmental problems are accentuated by their
high visibility. Limestone is extracted primarily from open pits.
Ammonium nitrate explosives are used extensively in operations.
Stones are dug from shattered piles by electrically powered shovels
and then processed by crushing and screening the limestone to the
required size.
Crushing and screening operations along with handling and storage
account for more than 99 percent of the particulate emissions
resulting from limestone quarrying. The remaining on-site emissions
results from combustion of fossil fuels. Table 19 summarizes the
environmental impacts associated with limestone quarrying. It can
be seen from this table that the dominant environmental effect of
limestone quarrying is particulate emissions.
Lime Production
Lime is produced by.the calcination of limestone in large rotary and
vertical kilns. During its passage through the kiln, any water
present is driven off and the limestone decomposes to lime (calcium
oxide) and carbon dioxide. The carbon dioxide passes out of the kiln
with the waste gases from fuel combustion and any particulates that
are lost. Particulate emissions from vertical and rotary kilns con-
sist of lime and fly ash from coal burning and amount to 4 kg/NTT
and 100 kg/MT of lime produced, respectively^11}. These sources can
be controlled by wet scrubbers or bag houses with a 97.1% and 93%
efficiency, respectively^?). Using these figures and the fact that
rotary kilns account for 80% of lime production, particulate emission
from processing are 5.62 kg/MT of lime produced. Particulate emissions
45
-------
TABLE 18. MODULE SUMMARY SHEET FOR IRON ORE MINING
Basis: 1 metric ton of iron ore
On-Site Off-Site
WATER DISCHARGES (liter)
Process 15,500 8
Mine Drainage 5
AIR EMISSIONS (grams)
Particulates 3,870 41
Sulfur Oxides 645 103
Carbon Monoxide 36 65
Hydrocarbons 12 167
Nitrogen Oxides 178 230
Aldehydes 1.4
Organics 0.6
WATER POLLUTANTS (grams)
Dissolved Solids 26
SOLID WASTES (kilograms)
Overburden 139
Process 3,600 4
ENERGY CONSUMPTION
Coal (kg) 12
Equivalent kcal 81,600
Liquid Hydrocarbon 5.76
Fuels (/)
Equivalent kcal 56,000
Natural Gas (m3) 4.46
Equivalent kcal 40,000
Electrical Energy (kwhr) 20. 5b
Equivalent kcal 61,200
Other kcal 17,700
Total kcal 256,500 11,200
TRANSPORTATION (metric ton-kilometers)
Rai 1 1 33
Water 508
Transportation Total Sources
9
15,508
5
11,47
201 4,112
34 782
114 215
164 343
243 651
11.8 13.2
2.2 2.8
26
48
139
3,604
16
115,000 382,700
17
46
-------
TABLE 19. SUMMARY SHEET FOR LIMESTONE QUARRYING
Basis: 1 metric ton of limestone
On-Site Off-Site Transportation Total Source
WATER DISCHARGED (liters) 9
Process 57
Mine Drainage 323 323
AIR EMISSIONS (grams) 11,47
Particulates 2,708 21 2,729
Sulfur Oxides 19 12 10 41
Carbon Monoxide 5 4 222 231
Hydrocarbons 9 10 72 91
Nitrogen Oxides 13 17 128 158
Aldehydes 0.6 3.2 3.8
Organics 0.2 6.6 6.8
SOLID WASTES (kilograms) 48
Overburden 5 5
Processing 80 80
ENERGY CONSUMPTION 16,21
Coal (kg) 0.073
Equivalent kcal 500
Liquid Hydrocarbon
Fuels (JZ.) 1.06
Equivalent kcal 9,700
Natural Gas (m3) 0.13
Equivalent kcal 1,200
Electrical Energy
(kwhr) 2.8
Equivalent kcal 8,300
Total kilocalories 19,700 1,300 36,800 57,800
TRANSPORTATION (metric ton-kilometer) 17
Rai1 16
Water 42
Truck 67
47
-------
also result from primary and secondary limestone crushers and are
reported to be 16.5 kg/MT of lime(H). These sources can be con-
trolled by baghouses with a 95% efficiency(47)_
Table 20 summarizes the environmental impacts which result from
the production of one metric ton of lime. It can be seen from
this table that the on-site impacts consist primarily of particu-
late, sulfur oxide and nitrogen oxide emissions. The off-site
impacts are primarily nitrogen and hydrocarbon emissions as well
as solid wastes.
Blast Furnace Area
The blast furnace area consists of sinter operations, the blast
furnace, and coke operations.
Sintering makes a lump feed for the blast furnace from materials
which once were wasted, including: the fine removed in the upgrading
of ores; flue dust, particles reclaimed from the gases in the blast
furnace; and coke breeze, fine dust-like bits of coke. Powdered
limestone may also be added.
All of these particles are spread out on a traveling belt which passes
through a furnace. Heat fuses them together into a porous, clinker-
like material called sinter. The sinter is then broken up into con-
venient sized pieces for feeding to the blast furnace.
Iron ore is converted into iron in the blast furnace. The charge to
the furnace is iron ore, coke and limestone. Hot air enters the
bottom of the furnace causing the coke to burn. The carbon of the
coke unites with oxygen in the air to form carbon monoxide which then
unites with the oxygen in the iron ore, liberating the iron. The
limestone is heated to a molten state and combines with most of the
silica and other impurities from the iron ore and coke forming a
molten slag.
Coke is made by the by-product method in long, high, narrow ovens
built in rows. The coal, crushed and washed, is blended and baked
without air at 1150°C with the necessary heat supplied from the ex-
ternal combustion of fuel gases. In most cases, about 40% of the
gases produced by coking are returned and used as fuel. When the
coking is completed, the coke is pushed from the oven by a "pusher"
into a quenching car. The coke lumps are quenched and then crushed
and screened.
48
-------
TABLE 20. ENVIRONMENTAL IMPACTS FOR LIME PRODUCTION
Basis: 1 metric ton of lime
On-Site Off-Site Transportation Total Source
MATERIAL INPUTS (kilograms) 49
Limestone 2,000 2,000
WATER DISCHARGED (liters) 50
Process 1,129 21 1,150
Mine Drainage 30 30
AIR EMISSIONS:(grams) 11,47
Particulates 6,450 184 15 6,649
Sulfur Oxides 3,542 160 33 3,735
Carbon Monoxide 45 478 302 825
Hydrocarbons 48 1,255 79 1,382
Nitrogen Oxides 1,033 1,447 167 2,647
Aldehydes 3.2 1.2 4.4 8.8
Organics 5.8 0.5 11.0 17.3
WATER POLLUTANTS (grams)
Dissolved Solids 137 137
SOLID WASTES (kilograms) 15
Overburden 810 810
Process 183 20 203
ENERGY CONSUMPTION 50
Coal (kg) 90
Equivalent kcal 612,000
Liquid Hydrocarbon
Fuels (i.) 4.2
Equivalent kcal 42,000
Natural Gas (m3) 52.1
Equivalent kcal 487,100
Electricity (kwhr) 31
Equivalent kcal 92,200
Total kcal 1,233,300 40,200 64,100 1,337,600
TRANSPORTATION 17
Rail 231
Truck 87
49
-------
It is generally conceded that coking operations constitute the
single greatest pollution problem to the steel industry. Signi-
ficant air emissions are particulate coke fines, sulfur oxides,
carbon monoxide and hydrocarbons. These emissions are associated
with the unloading, charging, discharging (i.e., "pushing") and
quenching of coke.
The distillates and fuel gases driven off during coke manufacture
are recovered as by-products (phenol, ammonia, light oil, benzene,
toluene, etc.) or used as fuels in the coking process, or in other
areas of the plants.
Most of the fuel gases driven off from the coal during coking are
burned to carry out the coking process on further batches of coal.
This procedure is known as "underfiring". Battelle(Sl) estimates
that 70% of underfiring energy is derived from the burning of coke
oven gas. Coke oven gas contains a significant quantity of H2S
which is emitted as 862 when the coke gas is burned. The estimated
uncontrolled emission rate of SO? during underfiring per metric ton
of coal charged is given as 5 kg/MT(H).
Emission figures used for byproduct coking were obtained from Compila-
tion of Air Pollution Emission Factors (11). These figures were
multiplied by 0.97 since 0.97 metric tons of coal are used to produce
the coke used in manufacturing one metric ton of pig iron. The con-
trol methods and their respective efficiencies were obtained from
Environmental Steel^52). Emissions from unloading the coal are
assumed to be controlled by enclosures, hoods and wetting. Charging
and discharging emissions are controlled by smokeless charging and
discharging. Emissions produced during coke cycling are controlled
by tight seals. Quenching emissions are controlled by closed quench-
ing and sulfur oxide emissions from underfiring are controlled
by desulfurization.
The blast furnace itself produces copious quantities of particulates
and carbon monoxide. However, blast furnace gas is recovered for
fuel values and effective control of particulates by a venturi scrubber
and/or an electrostatic precipitator is necessary to use the blast
furnace gas. Reference (11) gives the quantity of particulates and
CO as 75 and 700-1050 kg/MT of iron respectively before control and
0.75 and 0.0 kg/MT after control.
The same reference gives emissions of particulates and sulfur dioxide
from the sinter plant as 1.1 kg/MT iron ore and 0.750 kg/MT iron ore
respectively after control by a cyclone and electrostatic precipitator.
The total on-site emissions from the blast furnace, by-product coking
50
-------
and the sintering plant are summarized in Table 21. The on-site
water effluents shown in this table are those that will result
after 1977 water effluent guidelines are met for by-product coking
facilities and wash water from wet venturi scrubbing systems which
are used to control blast furnace air emissions'- •*.
Large amounts of slag (300 kg/MT iron) remain from the smelting of
ore in the blast furnace. However, it is estimated that the entire
annual production of blast furnace slag is utilized for road sub-
grades, building aggregate and other uses' '. The sluges and flue
dusts recovered from air and water cleaning are normally recycled
through the sinter strand. Therefore, the net output of on-site
solid waste is zero. However, there are 8.37 metric tons of solid
waste produced off-site for each metric ton of iron produced. This
waste results from off-site coal mining.
Oxygen Production
The steel industry consumes more oxygen than all other industries
combined, i->ing well over one-half of all oxygen produced in this
country. Oxygen is used in a variety of iron-and steel-making
operations ranging from scrap preparation to use in steel making
furnaces. The B.O.F. consumed 58% of the total oxygen consumed by
the steel industry in 1971(55).
Gaseous oxygen of the desired purity is produced from atmospheric
air by fractional distillation processes carried out at very low
temperatures and elevated pressures. The process starts by com-
pressing the air to an elevated pressure, followed by progressively
cooling it to saturation temperature in steps in a series of highly
efficient heat exchangers. Condensation and freezing out of moisture,
carbon dioxide, and hydrocarbons takes place as the temperature is
lowered, after which hydrocarbons still remaining are removed in
adsorbent traps. The cold, purified air is finally separated into
its components in fractionating (distillation) columns. The require-
ments for heat removal by refrigeration at the low temperature level
are met by expansion of a portion of the cold compressed air in an
expansion turbine.
Although most of the oxygen used by the steel industry is purchased
(81%), most oxygen plants are located quite close to their point of
consumption to minimize transportation difficulties. Therefore,
transportation impacts have not been considered. Table 22 summarizes
51
-------
TABLE 21. MODULE SUMMARY SHEET FOR
Basis : 1 metric ton of pig
MATERIAL INPUTS (kilograms)
Iron Ore
Limestone
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Participates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
Ammonia
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
Coal (kg)
Equivalent kcal 6
Liquid Hydrocarbon
Fuels (JL)
Equivalent kcal
Natural Gas (m3)
Equivalent kcal
Liquid Petroleum Gas (JL)
Equivalent kcal
Electricity (kwhr)
Equivalent kcal
Input Energy kcal 7
Output Energy kcal 2
Total kilocalories 4
iron
On-Site
1,610
242
70,242
1,900
1,670
326
837
11
--
--
81
14
5.
0.
0.
0.
6.
0.
9
972
,650,000
10.
106,500
19.
181,000
.
1,200
39.
117,900
,056,600
,441,000
,615,600
THE BLAST FURNACE
Off-Site
157
304
1,707
363
287
595
597
5.9
3.8
14
1,357
3
1 2
2
3
2
8
1
8,182
188
130,600
65
12,700
25
8,600
20
6
151,900 4
Total Source
55
1,610
242
56
70,399
304
11,52
3,607
2,033
613
1,332
608
5.9
3.8
81
53
28
1,357
5.3
2.1
2
0.3
0.2
7
0.1
9
8,182
188
55,56,57
,767,500
52
-------
TABLE 22. MODULE SUMMARY
Basis: 1000 m
WATER DISCHARGES (liters)
Process
Mine Drainage
AIR EMISSIONS (grains)
Parti culates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
Oil and Grease
Iron
SOLID WASTES (kilograms)
Overburden
Process
SHEET FOR OXYGEN PRODUCTION
On-Site Off-Site
34,973 188
48
531
2,959
1,234
3,120
5,061
10
2
300
2
1
1,308
58
Total Source
50
35,161
48
531
2,959
1,234
3,120
5,061
10
2
300
2
1
1,308
58
ENERGY CONSUMPTION 50
Liquid Hydrocarbon
Fuels (JL) 8.2
Equivalent kcal 76,700
Natural Gas (m3) 71.3
Equivalent kcal 667,000
Electricity (kwhr) 685
Equivalent kcal 2,039,000
Total kilocalories 2,782,700 41,400 2,824,100
53
-------
the environmental impacts resulting from oxygen manufacture. It
can be seen from this table that all the emissions, effluents and
solid waste are associated with off-site effects of energy use.
Basic Oxygen Furnace
The basic oxygen furnace, as presently used by the steel industry,
uses a high-pressure stream of oxygen (99.5 percent pure) to con-
vert iron (produced from virgin material) into steel. The charge
to the furnace consists of a reduced burden; pig iron and scrap;
slag-forming fluxes; burned lime, fluorspar and mill scale; and
sometimes an oxide charge; dry ore, sinter, pellets or mill scale.
A major advantage of the basic oxygen process is its flexibility in
handling raw materials of many types and compositions. The scrap
used can be either heavy or light, and the oxide charge, if used,
may be dry ore, sinter, pellets, or mill scale. The process can be
operated on any kind of hot metal that can be used in the basic open-
hearth furnace. In 1971, 30% of the metal charge to B.O.F. 's consisted
of scrap^5>), the major portion of which was home scrap from later
steel finishing operations.
Table 23 summarizes the environmental impacts resulting from the pro-
duction of one metric ton of carbon steel in a basic oxygen furnace.
Fuels for heating are derived from the blast furnace area and their
environmental impacts have been accounted for in that module.
The particulate emissions shown in Table 23 are those which will
result after "new source" standards for 1975 are met^58J. The neces-
sary control equipment is either electrostatic precipitators or high-
energy venturi scrubbers. The water effluents shown are those which
will result after 1977 water effJuent standards are met for gas washer
water from B.O.F. wet scrubbers
Solid wastes from the B.O.F. operation are slag and dust or sludge
from air cleaners. Approximately 132 kg of slag result per metric
ton of steel produced. Because of its higher density and other
properties, steel slag is not utilized to the extent that blast furnace
slag is used. The dust or sludge from emissions cleaning (23 kg/MT)
is either recycled to the sinter or landfilled with landfill a more
common practice (15 kg/MT have been assumed to be landfilled).
54
-------
TABLE 23. MODULE SUMMARY SHEET FOR THE BASIC OXYGEN FURNACE (30%
HOME SCRAP)
Basis: 1 metric ton of carbon steel ingot
MATERIAL INPUTS (kilograms)
Fluorspar
Limestone
Lime
Other Fluxes
Pig Iron
Scrap _
Oxygen (m )
WATER DISCHARGE (liters)
Process
AIR EMISSIONS (grams)
Particulates
WATER POLLUTANTS (grams)
Suspended Solids
Fluoride
SOLID WASTES (kilograms)
Processing
ENERGY CONSUMPTION
Coke Oven Gas (m )
Equivalent kcal
Blast Furnace Gas (m )
Equivalent kcal
Tar (JU
Equivalent kcal
Total kilocalories
On-Site
6.5
6.4
77.5
7.6
776
333
59.1
410
230
5
4.2
147
21.6
105,100
54.0
48,000
0.324
2,900
156,000
60
58
53
54
59
55
-------
Steel From Recycled Materials
Scrap steel from obsolete autos and steel cans was assumed to be used
in two ways by the steel industry in this study: (1) the scrap charge
to the Basic Oxygen Furnace was increased to 40% of the total metallic
charge, and (2) the scrap was consumed by electric furnaces.
Obsolete Scrap in the B.O.F.
The B.O.F. uses scrap not only as a source of metallies but also as
a coolant for controlling temperature. Consequently, scrap usage
cannot be arbitrarily changed without adjusting other variables to
maintain the thermal balance required for the fast, smooth, trouble-
free operation that is characteristic of the process. One method to
increase the percentage of scrap used in the B.O.F. is to preheat the
scrap charge. Consultation with the steel industry has revealed that
it would be realistic to increase scrap usage to 40% of the total
metallic charge by preheating. This increase would allow obsolete
scrap to replace 10% of the iron now used in the B.O.F. It would not
be realistic for obsolete scrap to replace the home scrap now being
used in the B.O.F. because this scrap would then present a solid waste
problem.
Figure 3 shows the arrangement of processes necessary to produce carbon
steel using a 40% scrap charge. The main difference between these systems
and Figure 2 for steel production from primary materials is that
resource recovery modules for obsolete scrap are included. All of
the modules shown in this figure have been previously summarized with
the exception for the B.O.F. with preheated scrap.
B.O.F. with Preheated Scrap. Table 24 summarizes the environmental
impacts associated with producing carbon steel in the B.O.F. with
preheated scrap. Comparison of this table with Table 23 for the B.O.F.
reveals that the primary effect of the additional scrap charge is the
need for additional fuel to preheat the scrap. This requirement
increases the on-site energy requirements for the B.O.F. and results
in off-site environmental effects.
56
-------
FIGURE 3.
System F2
System F3
System F4
System F5
STEEL PRODUCTION BY BASIC OXYGEN FURNACE USING OBSOLETE SCRAP (MIX-
SCRAP; 60% PIG IRON)
includes shredding
includes baling
includes MSW recovery
includes separated can recovery
30% HOME SCRAP; 10% OBSOLETE
AUTO HULK
PROCESSOR
MUNICIPAL
SOLID WASTE
RECOVERY
SEPARATED CAN
RECOVERY
(0.71 Hulks)
0.079 Hulks
(1060)
118
AUTO SCRAP
PROCESSOR
Shredder Baler
DETINNER
Obsolete Scrap
111
in
Home Scrap
333
IRON ORE
MINING
(1610)
1070
BLAST
FURNACE
AREA
LIMESTONE
QUARRYING
(242)
161
665
I
70.9
B.O.F. WITH
PREHEATED
SCRAP
5.8
(2000^
141
LIME
PRODUCTION
OXYGEN
1000
70.5
Numbers are kilograms of material required to produce one metric ton of steel ingot
Numbers in parenthesis arekkilograms of material required to produce one metric ton
of product from the next module
-------
TABLE 24. MODULE SUMMARY SHEET
(30% HOME SCRAP AND
Basis: 1 metric ton of carbon
MATERIAL INPUTS (kilograms)
Fluorspar
Limestone
Lime
Other Fluxes
Pig Iron
Scrap ,
Oxygen (m )
WATER DISCHARGED (liters)
Process
AIR EMISSIONS (grams)
P articulates
Carbon Monoxide
Sulfur Oxides
Hydrocarbons
Nitrogen Oxides
WATER POLLUTANTS (grams)
Suspended Solids
Fluoride
SOLID WASTES (kilograms)
Process
ENERGY CONSUMPTION
Natural Gas (m )
Equivalent kcal ,
Coke Oven Gas (m )
Equivalent kcal ,
Blast Furnace Gas (m )
Equivalent kcal
Tar (JL)
Equivalent kcal
Total kilocalories
FOR THE BASIC OXYGEN FURNACE
10% OBSOLETE SCRAP)
steel ingot
On-Site Off-Site
5.9
5.8
70.5
6.9
665
444
70.9
410 17
230 1
3
61
162
178
5
4.2
155
716
67,000
21.6
105,100
54.0
48,000
0.324
156,000
223,000 3,200
Total
5.9
5.8
70.5
6.9
665
444
70.9
467
231
3
61
162
178
5
4.2
155
226,200
Source
55,61
60
58
53
54
59,61
58
-------
Obsolete Scrap in the Electric Furnace
Since the heat source for the electric furnace is electricity,
thermal balance requirements do not limit the amount of scrap
consumed by the electric furnace.
In 1971, 99% of the metallic charge to the electric furnace con-
sisted of scrapf55). The scrap consisted of in-house waste and
high grade industrial waste resulting from metal discarded at
various stages in manufacturing as well as post-consumer ferrous
wastes. In this study the system we examined to recycle ferrous
scrap in the electric furnace is shown in Figure 4. It can be
seen from this figure that 70% of the scrap was assumed to come
from the resource recovery modules while the other 30% was home
scrap. All of the modules shown in this figure have been pre-
viously summarized with the exception of the Electric Furnace.
Electric Furnace. Most electric furnaces prior to 1960 did not
produce carbon steel but produced various ferroalloys for special
purposes. However, in 1971, 71% of the output of electric furnaces
was carbon steel. (55) Scrap metal and various additives are charged
into an electric furnace through its top. These materials are melted
by the conversion of electric energy into heat. Current is brought
into the furnace through large carbon electrodes and the energy is
converted to heat in the furnace. Since electricity furnishes heat
for the melting, there is no need for air to support combustion. High
purity oxygen can be injected through a lance during early stages of
the refining, raising the temperature and decreasing the time needed
to produce the finished steel. However, the quantity of oxygen entering
the furnace can always be closely controlled, thus minimizing undesirable
oxidizing reactions.
The material inputs to the electric furnace, as can be seen from
Table 25, are fluorspar, limestone, lime and other fluxes, scrap
ferrous metal and oxygen. It can also be seen from this table that
the on-site air emissions consist of particulates and carbon monoxide.
These emissions are based on proposed "new source" emission standards
for electric-ore furnaces^2) which are:
particulates - 0.03 kg/hr per metric ton of furnace capacity
CO - 0.03 kg/hr per metric ton of furnace capacity
59
-------
FIGURE 4. STEEL PRODUCTION BY THE ELECTRIC FURNACE (MIX: 30% HOME SCRAP, 70% OBSOLETE SCRAP)
System F5
System F6
System F7
System F8
Includes shredding
Includes baling
Includes MSW recovery
Includes separated can recovery
MUNICIPAL
SOLID WASTE
RECOVERY
AUTO HULK
PROCESSOR
(0.71 Hulks)
0.58 Hulks
SEPARATED
CAN
RECOVERY
(1060)
861
AUTO SCRAP
PROCESSOR
Shredder
DETINNING
Baler
Obsolete Scrap
812
LIMESTONE
QUARRYING
7.5
Home 348
Scrap
(2000)
59.2
-)
LIME
PRODUCTION
29.6
ELECTRIC
FURNACE
T^
1000
11.7 m
OXYGEN
PRODUCTION
Numbers are kilograms of material required to produce one metric ton of steel ingot.
Numbers in parenthesis are kilograms of material required to produce one metric ton of product
from the next module.
-------
TABLE 25. MODULE SUMMARY SHEET FOR THE ELECTRIC FURNACE
Basis: 1 metric ton carbon
MATERIAL INPUTS (kilograms)
Fluorspar
Limestone
Lime
Other Fluxes
Oxygen (m3)
Scrap
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
WATER POLLUTANTS (grams)
Dissolved Solids
Oil and Grease
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
steel
On-Site
27
7.5
29.6
1.9
11.7
1,160
63
120
1,200
70
Off-Site
161
41
446
2,510
534
1,290
2,818
8.3
257
2
1,122
50
Total
27
7.5
29.6
1.9
11.7
1,160
224
41
566
2,510
1,734
1,290
2,818
8.3
257
2
1,122
120
Source
55
60
62
63
Electricity (kwhr)
Equivalent kcal
Carbon Electrode (kg)
Equivalent kcal
Total kilocalories
588
1,750,500
5
38,800
- 1,789,300
1,789,300
61
-------
A four-hour heat has been assumed in this study.
The best air pollution control technology consists of baghouse filters
for particulate emission control with fume collection by the direct
evacuation method, whereby fumes are drawn from the shell of the
furnace, the CO burned, the gases cooled and then routed to the fil-
ters, plus a canopy hood for building evacuation to catch charging
and tapping emissions, as well as a direct evacuation system(°Z)_
Water effluents would result only if a wet scrubbing system were
used for control of air emissions and are not listed as an on-site
impact because fabric filters are assumed to be used for air emission
control.
The off-site impacts shown in Table 25 result from the consumption
of electrical energy.
Steel Systems Synthesis
This section summarizes the environmental impacts of nine systems
which produce carbon steel. The total impacts for each system were
determined using the detailed information contained in the module
summaries and known yield data, the kilograms of output from each
module necessary to produce one metric ton of carbon steel, as shown
in the detailed flowcharts (Figures 2, 3 and 4).
Virgin Materials in the B.O.F.
Figure 2 shows the modules and the outputs from each module which
are necessary to produce one metric ton of steel from virgin materials.
Table 26 shows the impacts which result from the individual modules in
the production of one metric ton of carbon steel from this system
(System Fl). The totals shown in the last column of this table are
the cumulative impacts of the individual modules, the impacts of the
whole system. In the case where an intermediate product such as pig
iron is produced, it is shown as an output from the blast furnace area
and an input to the B.O.F. The net effect is that pig iron is not
treated as a material input to the total system, rather the iron ore
which was used to make the pig iron in the blast furnace is the material
input to the system.
62
-------
TABLE 26. SUMMARY SHEET FOR CARBON STEEL PRODUCTION FROM VIRGIN MATERIALS IN THE BOF (SYSTEM Fl)
Basis: 1 metric ton of carbon steel
MATERIAL INPUTS (kilograms}
Iron Ore
Pig Iron
Scrap
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WA1ER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grains)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
Ammonia
WATER POLLUTANTS (grains)
Suspended Solids
Dissolved Solids
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
(Thousand Kilocalories)
Iron Ore
Mining
19,370
6
5,136
977
269
428
813
16
3
32
174
4,501
478.0
Limestone Lime
Mining Production
155
-77.5
20 89
113 2
953 515
14 289
81 64
32 107
55 205
1 1
2 1
11
1 63
28 16
20.2 103.7
Blast Furnace
Area
1,249
- 776
188
54,630
236
2,832
1,578
476
1,034
472
5
3
63
22
1,053
4
2
2
0.2
0.2
5
0.1
7
6,349
146
3,699.6
Oxygen
Production B.O.F. Total
1,249
776
333 333
6.4 349.4
77.5
6.5 6.5
7.6 7.6
-59.1 59.1
2078 410 76,597
3 360
31 230 9,697
175 3,033
73 963
184 1,785
299 1,844
1 24
8
63
5 27
18 1,114
4
2
2
0.2
0.2
5
0.1
4 11
78 6,665
3 147 4,841
166.9 156.0 4,624.4
-------
It can be seen from Table 26 that iron ore mining and the blast
furnace area account for most of the air emissions, water pollutants
and solid wastes from the system. They also account for 90% of the
energy used and 95% of the water discharged by this system.
Obsolete Scrap in the B.O.F.
Figure 3 shows the modules and the outputs from each module which
are necessary to produce one metric ton of carbon steel in a B.O.F.,
using ferrous scrap to comprise 40% of the total metallic charge to
the furnace. It can be seen from this figure that four systems of
ferrous scrap recovery have been considered:
F2 Ferrous scrap from an auto shredding operation
F3 Ferrous scrap from an auto baling operation
F4 Ferrous scrap from a municipal solid waste recovery
center
F5 Ferrous scrap from separated steel can collection
Tables 27-30 summarize the environmental impacts of these systems.
These tables also show the contributions of the individual modules
in each system. It can be seen from these tables that iron ore
mining and the blast furnace area account for most of the impacts
from these systems.
Obsolete Scrap in the Electric Furnace
Figure 4 shows the modules and the quantity of outputs from each
module which are necessary to produce one metric ton of carbon steel,
using 70% obsolete scrap and 30% home scrap, in an electric furnace.
It can be seen from this figure that the same four sources of ferrous
scrap that were considered for the B.O.F. are considered in this case.
Tables 31-34 summarize the environmental impacts resulting from the
production of one metric ton of carbon steel by these systems, as
well as the impacts from the individual modules. It can be seen
from these tables that the electric furnace with its high electrical
requirements accounts for most of the air emissions, water effluents
and solid wastes from these systems as well as more than 65% of the
energy consumed by these systems.
64
-------
TABLE 27. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE B 0 F (30°. HOME SCRAP, 101 OBSOLETE SCRAP FROM AUTO SHREDDER) SYSTEM F2
Basis: 1 metric ton of carbon steel
Iron Ore
Mining
Auto Hulk
Processor
Auto Scrap
Processor
Limestone
Mining
Lime
Production
Blast
Furnace
Oxygen
Production
B.O.F. with
Preheat
Total
MATERIAL INPUTS (kilograms)
Iron Ore
Pig Iron
Home Scrap
Obsolete bcrap
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process 16,594 1
Mine Drainage 5
AIR EMISSIONS (grams)
Particulates 4,400 1 6
Sulfur Oxides 837 2 27
Carbon Monoxide 230 121 59
Hydrocarbons 367 26 23
Nitrogen Oxide 697 31 49
Aldehydes 14 1 2
Organics 31 2
Ammonia
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids 28 2
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden 149 7
Process 3,856 11
Post-Consumer -121
ENERGY CONSUMPTION 409.5 6.5 24.4
(Thousand kilocalories)
18
99
823
13
71
28
49
1
2
2
25
17.8
141
-70.5
81
2
10
59
14
94.3
1,070
- 665
161
46,815
202
19
902
3
1
1
0.2
0.1
0.1
5,441
125
3,170.4
-70.9
2,493
3
469
263
58
97
187
1
1
2,427
1,352
408
886
404
4
3
54
38
210
87
221
359
1
21
93
4
200.2
665
333
111
5.8
70. S
5.9
6.9
70.9
427
231
3
61
162
178
15S
226.2
1,070
333
111
307.8
5.9
6.9
66.429
211
8,395
2,707
1,095
1,810
1.954
24
12
54
24
963
3
1
1
0 2
0.1
5
0.1
10
5,751
-1,190
- 121
•1,149.0
-------
TABLE 28. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE B.O.F. (30% HOME SCRAP, 10% OBSOLETE SCRAP FROM AN AUTO BALER) SYSTEM F5
Oasis.1 metric tun of carbon steel
Iron Ore
Mining
MATERIAL INPUTS (kilograms)
Iron Ore
Pig Iron
Home Scrap
Obsolete Scrap
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process 16,594
Mine Drainage 5
AIR EMISSIONS (grams)
Particulates 4,400
Sulfur Oxides 837
Carbon Monoxide 230
Hydrocarbons 367
Nitrogen Oxide 697
Aldehydes 14
Organics 3
Ammonia
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids 28
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden 149
Process 3,856
Post -consumer
Auto Hulk Auto Scrap Limestone Lime
Processor Processor Mining Production
141
-70.5
48 18 81
99 2
1 60 823 469
2 19 13 263
121 71 71 58
26 63 28 97
31 37 49 187
1311
1 17 2 1
4 10
6 7 59
2 11 14
-121
Blast Oxygen
Furnace Production
1,070
- 665
161
-70.9
46,815 2,493
202 3
2,427 38
1,352 210
408 87
886 221
404 359
4 1
3
54
19
902 21
3
1
1
0.2
0.1
5
0.1
6
5,441 93
125 4
B.O.F. with
Preheat
665
333
111
5.8
70.5
5.9
6.9
70.9
427
231
3
61
162
178
5
4
151
Total
1,070
333
111
307 8
5.9
6.9
66,476
211
8,449
2,699
1.107
1,850
1,942
25
27
54
24
965
3
1
1
0.
0.
5
0
10
3.-5C
-,:s:
- 121
ENERGY CONSUMPTION
(Thousand kilocalones)
409.5
6.5
43.9
17.8
94 3
3,170.4 200.2
226 2
-------
TABLE 29. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE B.O.F. (30% HOiME SCRAP, 10% OBSOLETE SCRAP FROM MUNICIPAL SOLID WASTES, SYSTEM F4
Basis 1 metric ton of carbon steel
Municipal
Iron Ore Solid Waste Limestone Lime Blast Oxygen BOF with
Mining Recovery Petinning Mining Production Furnace Production Preheat
Total
MATERIAL INPUTS (kilograms)
Iron Ore
Pig Iron
Home Scrap
Obsolete Scrap
Detinned Scrap
Limestone
Lime
Fluorspar
Other Fluxes
Sodium Hydroxide
Sodium Nitrate
Oxygen (m3)
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
Ammonia
16,594
5
4,400
837
230
367
697
14
3
28
16
61
20
44
1
2
118
-111
10.6
0.9
12
56
6
16
32
18
99
823
13
71
28
49
1
2
141
70.5
81
2
469
263
58
97
187
1
1
1,070
- 665
161
46,815
202
2,427
1,352
408
886
404
4
3
54
-70.9
2,493
3
38
210
87
221
359
1
665
333
111
5.8
70.5
5.9
6.9
70.9
427
231
61
162
178
1,070
333
118
307.8
5.9
6.9
10.6
0.9
66.430
211
8.428
2.750
982
1.797
1.950
22
11
54
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids 28
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden 149
Process 3,856
Post-consumer
ENERGY CONSUMPTION 409.5
(Thousand kilocalories)
4
30
-148
18.9
9
18
26.2
17.8
10
59
14
94.3
19
902
3
1
1
0.
0.
0.1
5,441
125
5,170.4
21
93
4
200.2
151
226.2
24
966
3
1
1
0.
0.
5
0.
10
5,757
4,227
- 148
•1,163.2
-------
1ABLE 30. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE B.O.F. (301 HOME SCRAP, 101 OBSOLETE SCRAP FROM SEPARATED STEEL CANS) SYSTEM F5
Basis • 1 metric ton of carbon steel
Iron Ore
Mining
MATERIAL INPUTS (kilograms)
Iron Ore
Pig Iron
Home Scrap
Obsolete Scrap
Detinned Scrap
Limestone
Lime
Fluorspar
Other Fluxes
Sodium Hydroxide
Sodium Nitrate
Oxygen (m^)
WATER DISCHARGED (liters)
Process 16,594
Mine Drainage 5
AIR EMISSIONS (grams)
Particulates 440
Sulfur Oxides 837
Carbon Monoxide 230
Hydrocarbons 367
Nitrogen Oxide 697
Aldehydes 14
Organics 3
Ammonia
WATER POLLUTANTS (grams)
Suspended Solids
BOD
Oil and Grease
Iron
Dissolved Solids 28
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden 149
Process 3,856
Post-consumer
ENERGY CONSUMPTION 409.5
(Thousand kilocalories)
Separated
Steel Cans
Limestone
Petinning Mining
6
23
62
24
52
1
2
-118
24.0
118
-111
10.6
0.9
12
56
6
16
32
9
18
18
99
823
13
71
28
49
1
2
Lime Blast
Production Furnace
1,070
- 665
Oxygen
Production
141
70.5
81
2
10
26.2 17.8
59
14
94.3
161
46,815
202
19
3
1
1
902
0.2
0.1
5
0.1
6
5,441
125
3,170.4
-70.9
2,493
3
21
93
4
200.2
BOF with
Preheat
665
333
111
5.8
70.5
5.9
6.9
70.9
427
151
226.2
Total
1,070
333
118
307.8
5.9
6.9
10.6
0.9
66,430
211
469
263
58
97
187
1
1
2,427
1,352
408
886
404
4
3
54
38
210
87
221
359
1
231
3
61
162
178
8,406
2,757
983
1,801
1,958
22
11
54
24
3
1
1
968
0.
0.
5
0.
10
576.1
4.1S7
-118
4,168 5
-------
TABLE 31. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE ELECTRIC FURNACE (30% HOME SCRAP, 70% OBSOLETE SCRAP FROM AN AUTO SHREDDER)
SYSTEM F6
Basis: 1 metric ton of carbon steel
Limestone
Mining
MATERIAL INPUTS (kilograms)
Obsolete Scrap
Home Scrap
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
Oil and Grease
SOLID WASTES (kilograms)
Overburden
Process
Post-consumer
ENERGY CONSUMPTION
(Thousand kilocalories)
3
19
162
3
15
6
11
Lime
Production
59.2
-29.6
38
223
111
24
41
78
3.9
27
1
39.6
Auto Hulk
Processing
9
15
886
192
227
5
10
Auto Scrap
Processing
7
2
43
201
430
166
356
16
15
11
52
79
Oxygen
Production
-11.7
411
1
6
35
14
37
59
4
15
< 1
Electric
Furnace
812
348
7.5
29.6
2.7
1.9
11.7
224
41
566
2,510
1,734
1,290
2,818
8
257
2
1.122
20
-889
47.9
178.3
33.0
1,789.3
Total
812
348
66.7
2.7
1.9
683
63
1,009
2,875
3,103
1,732
3,549
29
26
277
2
1216
105
-889
2092.0
-------
TABLE 32. SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE ELECTRIC FURNACE
Basis- 1 metric ton of carbon steel
Limestone Lime Auto Hulk
Mining Production Processing
MATERIAL INPUTS (kilograms)
Obsolete Scrap
Home Scrap
Limestone 59 . 2
Lime -29.6
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process 3 38
Mine Drainage 19
AIR EMISSIONS (grams)
Particulates 162 223 9
Sulfur Oxides 3 111 15
Carbon Monoxide 15 24 886
Hydrocarbons 6 41 192
Nitrogen Oxide 11 78 227
Aldehydes 5
Organics 1 10
WATER POLLUTANTS (grams)
Dissolved Solids 5
Oil and Grease
SOLID WASTES (kilograms)
Overburden 27
Process 5 1
Post-consumer -889
(30% HOME SCRAP,
Auto Scrap
Processing
35
2
435
142
519
458
268
24
121
26
41
13
70% OBSOLETE SCRAP FROM
SYSTEM
Oxygen Electric
Production Furnace
812
348
7.5
29.6
2.7
1.9
-11.7 11.7
411 224
1 41
6 566
35 2,510
14 1,734
37 1,290
59 2,818
8
4 257
2
15 1,122
< 1 20
AN AUTO BALER)
F7
Total
812
348
66.7
2.7
1.9
711
63
1,401
2,816
3,192
2,024
3,461
37
132
292
2
1,195
39
-889
ENERGY CONSUMPTION
(Thousand kilocalories)
3.9
39.6
47.9
321.1
33.0
1,789.3
2,234.8
-------
TABLE 33. MODULE SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE ELECTRIC FURNACE (30% HOME SCRAP, 70% OBSOLETE SCRAP F.ROM MUNICIPAL
SOLID WASTE) SYSTEM F8
Basis: 1 metric ton of carbon steel
MATERIAL INPUTS (kilograms)
Obsolete Scrap
Detinned Scrap
Home Scrap
Sodium Nitrate
NaCl
NaOH
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Participates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
Oil and Grease
SOLID WASTES (kilograms)
Overburden
Process
Post-consumer
ENERGY CONSUMPTION
(Thousand kilocalories)
Limestone
Mining
3
19
162
3
15
6
11
5
3.9
Lime
Production
59.2
-29.6
38
223
111
24
41
78
1
5
27
1
39.6
Rock Salt
Mining
175
7
9
34
31
58
1
3
14
11
29.5
Caustic Soda
Production
79
-77. S
327
11
116
655
139
334
734
2
68
293
13
456.8
MSW
Recovery
205
117
444
147
319
1
33
217
-1,076
137.8
De tinning
861
-812
6.2
77.5
17
2
89
412
46
120
231
1
15
33
66
132
191.6
Oxygen
Production
-11.7
411
1
6
35
14
37
59
4
15
< 1
33.0
Electric
Furnace
812
348
7.5
29.6
2.7
1.9
11.7
224
41
566
2,510
1,734
1,290
2,818
8
257
2
1,122
20
1,789.3
Total
861
348
6.2
79
66.7
2.7
1.9
1,195
74
1,374
3,852
2,450
2,006
4,308
12
17
369
2
1,570
399
-1,076
2,681.5
-------
TABLE 34. MODULE SUMMARY SHEET FOR CARBON STEEL PRODUCTION IN THE ELECTRIC FURNACE (30%
STEEL O>NS) SYSTEM F9
Basis : 1 metric ton of carbon steel
Limestone
Mining
MATERIAL INPUTS (kilograms)
Obsolete Scrap
Detinned Scrap
Home Scrap
Sodium Nitrate
NaCl
NaOH
Limestone
Lime
Fluorspar
Other Fluxes
Oxygen (m3)
WATER DISCHARGED (liters)
Process 3
Mine Drainage 19
AIR EMISSIONS (grams)
Participates 162
Sulfur Oxides 3
Carbon monoxide 15
Hydrocarbons 6
Nitrogen Oxide 11
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
Oil and Grease
SOLID WASTES (kilograms)
Overburden
Process 5
Post-consumer
Lime
Production
59.2
-29.6
38
223
111
24
41
78
1
5
27
1
Rock Salt
Mining
175
7
9
34
31
58
1
3
14
11
Caustic Soda
Production
79
-77.5
327
11
116
655
139
334
734
2
68
293
13
Separated
Can
8
2
42
170
455
175
378
6
15
13
56
3
-861
HOME SCRAP,
Detinning
861
-812
6.2
77.5
17
2
89
412
46
120
231
1
15
33
66
132
701 OBSOLETE SCRAP FROM
Oxygen Electric
Production Furnace
812
348
7.5
29.6
2.7
1.9
-11.7 11.7
411 224
1 41
6 566
35 2,510
14 1,734
37 1,290
59 2,818
8
4 257
2
15 1,122
< :• 20
SEPARATED
Total
861
348
6.2
79
66.7
2.7
1.9
1,203
76
1,211
3,905
2,461
2,034
4,367
17
32
382
2
1,593
185
-861
ENERGY CONSUMPTION
(Thousand kilocalories)
3.9
39.6
29.5
456.8
175.0
191.6
33.0
1,789.3
2, "18
-------
Environmental Impact Comparisons
Nine systems have been considered for the production of carbon
steel. It was seen in the previous section that these systems
could be classified into three groups.
I. System Fl. Steel Production from Virgin Materials
in the B.O.F.
II. Systems F2, F3, F4 and F5. Steel Production from
Virgin Materials and Obsolete Scrap in the B.O.F.
III. Systems F6, F7, F8 and F9. Steel Production from
Obsolete Scrap in the Electric Furnace.
It also was seen in the previous section that the environmental
impacts do vary greatly between systems in the same group. Therefore,
the most meaningful analysis of the environmental impact of systems
using virgin materials and/or obsolete scrap can be made if System Fl
is compared with systems in Group II and then with systems in
Group III.
Systems Fl Vs. Systems F2, F3, F4 and F5
Table 35 shows the environmental impacts for the systems which
produce carbon steel in the BOF from virgin materials (System Fl)
and from virgin materials and obsolete scrap (Systems F2, F3, F4
and F5). It can be seen from this table that Systems F2, F3, F4 and
F5 consume 210 to 223 kilograms less of virgin material than
System Fl.
It can also be seen from Table 35 that Systems F2, F3, F4 and F5
have reduced water use by at least 10,288 liters (13%) and
energy consumption by 455,000 kilowatt hours (10%) as compared to
System Fl. Total air emissions have been reduced by at least 1268
grams (7%). However, there are slight increases in carbon monoxide,
hydrocarbon and nitrogen oxide emissions from Systems F2, F3, F4 and
F5 which result from the off-site impacts or natural gas use in
preheating the scrap. Water pollutants are reduced by at least 153
grams (13%). Solid wastes are cut at least 1666 kilograms (14%).
Overall, there is slight reduction in all impacts from the systems
using obsolete ferrous scrap in the BOF with very little to choose
between the four systems. However, this result is not unexpected
because the obsolete ferrous only comprises 10% (111 kilograms) of
73
-------
TABLE 35. COMPARISON OF ENVIRONMENTAL IMPACTS FOR THE 1'RODUCTION OF CARBON SIEEL USING VIRGIN AND/OR RECYCLED MATERIALS
F7
Basis • 1 metric ton of carbon steel ingot F5 F6 Electric T8
Fl
BOF
Virgin
F2
BOF Auto
Shredder Scrap
F3
BOF Auto
Baler Scrap
F4
BOF MSW
Scrap
BOF Separated Electric
Steel
Can Scrap
Furnace Auto
Shredder Scrap
Furnace
Auto
Baler Scrap
Electric
Furnace
MSN Scrap
F9
Electric
Furnace
Steel
Can Scrap
MATERIAL INPUTS (kilograms)
Total Raw Materials
Iron Ore
Limestone
NaCl
Sodium Nitrate
Fluorspar
Other Fluxes
Home Scrap
Obsolete Scrap
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grains)
Participates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
Ammonia
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
BOD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden
Process
Post-consumer
ENERGY CONSUMPTION
1,612.5
1,249
349.4
6.5
7.6
333
76,975
76.615
360
17,421
9.697
3,033
963
1,785
1,844
24
8
63
1,165.5
27
1,114
4
2
2
0.2
0.2
5
0.1
11
11,506
6.665
4,841
4,624.4
1,390.6
1,070
307.8
S.9
6.9
333
111
66.640
66,429
211
16,051
8.595
2,707
1,095
1,810
1,954
24
12
54
1,007.4
24
963
3
1
1
0.2
0.1
5
0.1
10
9,820
5,751
4,190
-121
4,149.0
1,390.6
1,070
307.8
5.9
6.9
333
111
66,687
66,476
211
16,153
8,449
2,699
1,107
1,850
1,942
25
27
54
1,009.4
24
965
3
1
1
0.2
0.1
5
0.1
10
9,810
5,750
4,181
-121
4,168.5
1,402.3
1,070
307.8
10.8
0.9
5.9
6.9
333
111
66,641
66,430
211
15,994
8,428
2,750
982
1,797
1,950
22
11
54
1,010.4
24
966
3
1
1
0.2
0.1
5
0.1
10
9,836
5,757
4,227
-148
4,163.2
1,402.3
1,070
307.8
10.8
0.9
5.9
6.9
333
111
66,641
66,430
211
16,012
8,406
2,757
983
1,801
1,958
22
11
54
1,012.4
24
968
3
1
1
0.2
0.1
5
0.1
10
9,840
5,761
4,197
-118
4,168.3
71.3
66.7
2.7
1.9
348
812
746
683
63
12,323
1,009
2,875
3,103
1,732
3,549
29
26
279
277
2
429
1,206
112
-889
2,093 8
71.3
66.7
2.7
1.9
348
812
774
711
63
13,063
1,401
2,816
3,192
2,024
3,461
37
132
294
292
2
352
1,195
46
-889
2,234 3
1S6.5
66.7
79
6.2
2.7
1.9
348
861
1.269
1,195
74
14.019
1.374
3,852
2,450
2,006
4,308
12
17
371
369
2
900
1,570
406
-1,076
2,681.5
156.
66.
79
6.
2.
1.
348
816
1,279
1,203
76
14,027
1,211
3,905
2,461
2,034
4,367
17
32
384
382
2
924
1,593
192
-861
2,718.
5
7
2
7
9
1
(Thousand kilocalories)
-------
the metallic charge to the furnace. Since the pig iron charge
to the furnace was dropped from 776 kilograms to 665 kilograms
(14%) to allow for the increased scrap usage, the largest change
in impacts by using scrap would be 14% if there were no impacts
attributable to the resource recovery modules.
In summary, there is a definite decrease in environmental impacts
which result from using a 10% obsolete scrap charge to the EOF.
However, the changes are small because only 14% of the metallic
charge coming directly from iron ore has been replaced. There is
also very little difference in the environmental impacts resulting
from Systems F2, F3, F4 and F5.
System Fl Vs. Systems F6, F7, F8 and F9
Table 35 shows the environmental impacts from the system which
produces carbon steel in the EOF (System Fl) and the four systems
which use obsolete scrap to produce carbon steel in the electric
furnace (Systems F6, F7, F8 and F9). It can be seen from this table
that Systems F6 and F7 cut raw materials consumption by 1541 kilograms
(96%) while Systems F8 and F9 cut raw materials consumption by 1456
kilograms (90%). Water use was cut by at least 75,696 liters (98%)
by Systems F6, F7 F8 and F9. The decrease in energy consumption
as compared to System Fl ranged from 2530.6 kilowatt hours (55%)
for System F6 to 1906 kilowatt hours (41%) for System F9.
Total air emissions decreased from between 5098 grains (29%) for
System F6 to 3394 grams (19%) for System F9. This decrease was
primarily due to a large decrease in particulate emissions which
resulted from iron ore mining and the blast furnace area of System Fl.
Gaseous emissions from Systems F6, F7, F8 and F9 were generally
greater than those from System Fl because of increased electricity
consumption by these systems.
Water pollutants resulting from Systems F6, F7, F8 and F9 decreased
by at least 781 grams (67%). The largest decrease in wastes as
compared to System Fl was in solid wastes produced. Changes ranged
from 11,154 kilograms (97%) for System F7 to 10,582 kilograms (92%) for
System F9.
It can also be seen from Table 35 that System F6 had the minimum
environmental impacts of any of the systems consuming obsolete scrap
in the electric furnace while System F9 had the greatest. The impacts
75
-------
of these systems were determined largely by the amount of energy
consumed.
In summary, the environmental impacts from the systems (F6, F7, F8
and F9) using obsolete scrap in the electric furnace were less
than the impacts from the system (Fl) using virgin materials in
the EOF. The greatest changes were seen in raw material consumption,
water use, energy consumption and solid wastes.
Pollution Control Costs for Steel
An assumption basic to this study was that 1975 Air Standards and
1977 Water Standards would be met. Air emissions and water effluents
were reported with this premise in mind. However, there is a real
dollar cost to industry in meeting these standards. When sufficient
data were available, cost estimates for meeting the standards were
developed for each module. However, there were not sufficient data
available to determine the total cost of meeting the standards for
each system studied. Therefore, in order to keep the cost data
comparable for all the systems, cost estimates were only developed for
the direct cost to the steel industry in meeting 1975 Air Standards
and 1977 Water Standards.
Table 36 summarizes the pollution control costs for steel production.
The costs shown in this table are the net annual costs per metric
ton of steel produced. The net annual cost per metric ton of steel
was computed by summing the annual operating costs which include
costs for power, materials, labor, maintenance, taxes, insurances
and interest; with the depreciation on the capital investment, and
then subtracting the credit for returned materials. The unit costs
shown in column 1 of Table 36 are costs for the types of pollution
control equipment which were previously discussed in the module
descriptions.
It can be seen from Table 36 that the control costs for System Fl,
which consumes virgin materials in the B.O.F. are $5.58-6.46 per
metric ton of steel. Pollution control costs for Systems F2, F3,
F4 and F5 which consume virgin materials and obsolete scrap in
the B.O.F. are $4.97-5.79 per metric ton of steel. The costs for
Systems F2, F3, F4 and F5 are less than System Fl because these systems
consumed only 84% as much pig iron as does System Fl. The pollution
control costs for Systems F6, F7, F8 and F9 which consume obsolete
scrap in an electric furnace are only $2.30 per metric ton of steel.
This lower cost results because the blast furnace area costs are not
included since no pig iron is consumed by these systems.
76
-------
TABLE 36. POLLUTION CONTROL
BLAST FURNACE AREA
Total
Blast Furnace
Air
Water
Sinter
Air
Coking
Air
Charging
Pushing
Quenching
Desulfurization
Water
BASIC OXYGEN FURNACE
(Total)
Air
Water
ELECTRIC FURNACE
Total
Air
COSTS FOR STEEL: NET ANNUAL COSTS
Cost to Cost to
Unit Cost to Systems Systems
Costs System Fl F2,F3,F4&F5 F6.F7.F85F9
$/MT of steel $/MT of steel $/MT of steel
$/MT of iron
5.49 - 6.02 4.26 - 4.67 3.65 - 4.00
0.32
0.49
0.84
0.62
0.62
1.69 - 2.22
0.55
0.36
$/MT of steel
1.32-1.79 1.32-1.79 1.32-1.79
1.23 - 1.68
0.09
$/MT of steel
2.30 2.30
2.30
Source
74
53
74
74
53
58
53
62
TOTAL
5.58 - 6.46
4.97 - 5.79
2.30
-------
SECTION VI
ALUMINUM
Aluminum from Virgin Materials
This section describes the operations necessary to produce aluminum
from virgin materials. Figure 5 shows the arrangement of processes
necessary for primary aluminum production. It can be seen from this
figure that bauxite ore is the basic raw material for aluminum.
Lime, which is produced from limestone, and caustic soda, which is
produced from rock salt, are used to convert the bauxite ore into
alumina. The alumina is then smelted in electrolytic cells into
aluminum.
Bauxite Mining
Bauxite ore is at the present time the only commercially exploited
source of aluminum. Although other types of earth, including
ordinary clay, contain aluminum, industry economics favor bauxite
as the preferred ore. Although the United States is the world's
largest consumer of bauxite, nearly 90 percent of the bauxite used
here is imported.
Most bauxite is mined by open-pit methods. In Arkansas, the top
domestic producing region, open-pit mining is used, with stripping
ratios of 10 feet of overburden to 1 foot of ore considered minable.
Underground mining is employed at one location in Arkansas. On-site
treatment of bauxite usually includes crushing, classifying, washing,
and dehydration. For some end uses, a more complete dehydrating
process, such as calcination, is required.
The mining, crushing and dehydration of bauxite ore results in the
generation of particulate air emissions, which amount to 2.7 kg/MT
of bauxite.(11.47) 7he combustion of fossil fuels results in additional
particulate emissions and gaseous emissions as shown in Table 37, which
summarizes the environmental impacts of bauxite mining. It can also
be seen from this table that solid wastes are the primary environmental
impact of bauxite mining.
78
-------
FIGURE 5. PRIMARY ALUMINUM PRODUCTION FROM VIRGIN MATERIALS
SYSTEM Al
Limestone
Mining
Bauxite
Mining
Rock
Salt
Mining
[ZOOO)
(60) v
115.8
5134
C102(0
(72.4)
139.7
Lime
Manufacture
(
(2660)
Caustic
Soda
Manufacture
3C
• r
»
\
•7
U)
57.9
— H MiiuiiJ.ua iQ^n Hiuminuni
» Refining Smelting
137
100U
units in kilograms: no parentheses aluminum production
( ) alumina refining,
r ~] lime or caustic soda manufacture.
79
-------
TABLE 37. MODULE SUMMARY SHLIZT FOR BAUXITU MINING
Basis: 1 metric ton of bauxite
On Site Off Site Transportation Total Source
WATER DISCHARGED (liters] 9
Process 66 30 96
AIR EMISSIONS (grams) 11,47
Particulates 2,706 9 592 3,307
Sulfur Oxides 18 45 64 127
Carbon Monoxide 144 120 299 463
Hydrocarbons 35 312 473 820
Nitrogen Oxides 63 374 712 1,149
Aldehydes 2.0 0.1 33.5 35.6
Organics 1.9 2.0 3.9
SOLID WASTES (kilograms) 48
Processing 2,650 2,650
ENERGY CONSUMPTION 16
Liquid Hydrocarbon
fuels (£ ) 1.69
Equivalent kcal 15,000
Natural gas (nT) 11.65
Equivalent kcal 108,900
Electrical Energy
(kw-hr) 8.0
Equivalent kcal 23,800
Other fuels (kcal) 22,200
Total kilocalories 169,900 7,300 301,700 478,900
TRANSPORTATION (metric-
ton kilometers) 17
Truck 16
Water 1527
80
-------
Rock Salt Mining
The refining of bauxite ore to alumina employs strong caustic soda
solutions. Secondary aluminum smelting operations use chlorine gas.
The major raw material for caustic soda and chlorine is salt. It
was assumed here that this salt is obtained by the mining of rock
salt. Rock salt mines are widely distributed throughout the United
States, with 17 states reporting production in 1969.(48^
Table 38 shows the environmental impacts from rock salt manufacture.
It is clear from this table that the environmental impacts of rock
salt mining are relatively small and are mainly off-site effects
resulting from the use of electricity.
Caustic Soda and Chlorine Manufacture
Caustic soda (sodium hydroxide) and chlorine are manufactured from salt
by an electrolytic process. The aqueous brine (NaCl) solution
is electrolyzed to produce caustic soda, chlorine, and hydrogen
gas. The chlorine and caustic soda each account for about half the
output of the process, with hydrogen amounting to only 1 percent by
weight. Therefore, half the impacts of the process are allocated to
chlorine production and half to caustic soda production. The impacts
allocated to caustic soda and chlorine manufacture are presented in
Table 39.
Alumina Refining
Bauxite ore must be refined to nearly pure aluminum oxide (alumina),
A1203, before it can be used in the manufacture of metallic aluminum.
Virtually all of the commercially produced alumina is obtained through
the Bayer Process. In this process, the beneficiated bauxite is first
ground and then digested by caustic soda and lime at elevated temperature
and pressure. The resulting sodium aluminate solution is separated
from the insoluble tailings (red mud) by countercurrent decantation and
filtration. The liquor is cooled until it becomes supersaturated and
is then seeded with crystals of aluminum trihydrate. The aluminum in
solution is precipitated as the trihydrate and then filte.red and washed.
Caustic soda, together with the unprecipitated aluminum, is recycled to
the digester. The filtered and washed aluminum trihydrate is then
calcined to alumina, generally in a rotary kiln.
81
-------
TABLE 38. MODULE SUMMARY SHEET FOR MINING ROCK SALT
Basis: 1 metric ton of rock salt
On Site Off Site Transportation Total
WATER DISCHARGED (liters)
Process 2178 37 2215
AIR EMISSIONS (grans)
Particulates 64 25 89
Sufur Oxides 14 36 59 109
Carbon Monoxide 116 308 424
Hydrocarbons 3 293 95 391
Nitrogen Oxides 22 524 187 733
Aldehydes 0.2 5.7 5.9
Organics 0.5 13.1 13.6
WATER POLLUTANTS (grams)
Dissolved Solids 41 41
SOLID WASTES (kilograms)
Overburden 179 179
Process 132 8 140
ENERGY CONSUMPTION
Liquid Hydrocarbon
fuels (;&-) 0.5
Equivalent kcal 5,000
Natural Gas (m ) 4.75
Equivalent kcal 44,400
Electricity (kw-hr) 94
Equivalent kcal 279,000
Total kcal 276,400 2,100 93,500 374,000
TRANSPORTATION (metric
ton-kilometers)
Rail 482
Truck 80
Source
9
11
21
21
17
82
-------
TABLE 39. MODULE SUMMARY SHEET FOR CAUSTIC SODA OR CHLORINE MANUFACTURE
Basis: 1 metric ton
On Site
MATERIAL INPUTS (kilograms)
NaCl 1,020
WATER DISCHARGED (liters)
Process 3,678
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
BOD
COD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
SOLID WASTES (kilograms)
Overburden
Process
Off Site
542
139
1,503
8,453
1,798
4,308
9,474
28.1
40
10
865
10
28
6
2
0.6
0.6
1
3,780
166
Total
1,020
4,220
139
1,503
8,453
1,798
4,308
9,474
28.1
40
10
865
10
28
6
2
0.6
0.6
1
3,780
166
Source
17,64
17,64
ENERGY CONSUMPTION
Electricity (kw-hr) 1,980
Equivalent kcal 5,894,500
Total kilocalories 5,894,500 5,894,500
83
-------
Table 40 summarizes the environmental impacts associated with
alumina production. The particulate emissions result from grinding
of bauxite (3 kg/MT bauxite, uncontrolled) and from the calcining of
the alumina (100 kg/MT of alumina, uncontrolled). The emissions from
grinding operations were assumed to be controlled by baghouses
with a 95% collection efficiency. The emissions from the calcining
operation were assumed to be controlled by cyclones followed by
electrostatic precipitators with overall efficiency of control of 99%
in order to recover the valuable alumina. The other air emissions
shown in Table 4 result from the on-site combustion of fuel for
calcination.
The absence of on-site water effluents is due to 1977 Water Effluent
Standards which call for zero discharge of water effluents by the
total impoundment of water.(65) The 300 kg of solid wastes are the
solids in mud slurries which are discharged in settling ponds for
impoundment.
Primary Aluminum Smelting
Primary aluminum is produced by the electrolysis of alumina in a
molten bath of cryolite and aluminum fluoride. Carbon anodes are
inserted through the surface of the molten bath. The carbon lining
of the cell serves as the cathode where the metallic aluminum
collects. Anodes are consumed during the reaction at a rate of
approximately 600 kg of material per metric ton of aluminum produced.
Two major types of electrolytic cells are the prebake and the Soderberg.
Prebake furnaces require an additional facility to bake the anodes
before they are used in the furnace. Soderberg cells are classified
as horizontal or vertical depending on the arrangement of the steel
anode studs in a vertical or horizontal position. The amounts of
pollutants emitted from aluminum potlines depends on which of the
above types of pots is used. Collection and treatment efficiency
also differ depending on the type of potline.
The primary pollution problem at the smelter site is fluoride emissions
from the cryolite baths. These occur as both particulate and gaseous
atmospheric emissions, and as waterborne wastes when wet scrubbing is
used for air pollution control.
The type of plant considered in this module uses a prebake anode cell.
The reason for this selection was that industry has not built any
new Soderberg plants in recent years because prebake cells are able
to achieve higher current efficiencies.(65) Since a prebake plant
was chosen as the study plant, it was also necessary to consider the
anode bake furnace.
84
-------
TABLE 40. MODULE SUMMARY
SHEET
FOR ALUMINA PRODUCTION
Basis: 1 metric ton of alumina
On
MATERIAL INPUTS (kilograms)
Bauxite 2
Caustic Soda
Lime
WATER DISCHARGED (liters)
Process 2
Mine Drainage
AIR EMISSIONS (grams)
Particulates 1
Sulfur Oxides 3
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides 2
Aldehydes
Organics
WATER POLLUTANTS (grams)
Dissolved Solids
BOD
COD
Oil and Grease
Phenols
Sulfide
Ammonia
SOLID WASTES (kilograms)
Overburden
Process
Site
,660
71
30
,000
,400
,125
6
341
,531
36
53
300
Off Site Transportation
1,226
4
123 408
494 133
4,164 289
11,052 363
12,173 540
7.2 26.6
2.5 11.4
296
11
36
5
1
1
1
105
5
Total Source
46
2,660
71
30
17
3,226
4
11,47
1,931
3,752
4,459
11,756
13,244
70
67
296
11
36
5
1
1
1
10
105
305
ENERGY CONSUMPTION 66
Liquid Hydrocarbon
fuels (/ ) 108
Equivalent kcal 1,080,000
Natural Gas (m3) 473.8
Equivalent kcal 4,430,000
Electrical Energy
(kw-hr) 55
Equivalent kcal 163,700
Total kilocalories 5,673,700 339,100 299,300 6,312,100
TRANSPORTATION 17
Rail 884
Water 964
85
-------
The air pollution control system for the prebake cell was assumed
to be a hood with a collection efficiency of 97%-99% followed
by a fluidized bed dry scrubber. No secondary control was assumed
to be needed to meet 1975 standards which call for a maximum water
soluble fluoride emission of 1 kg/MT (95% of fluorides are water
soluble) for the entire primary aluminum smelting plant. Particulate
emissions of 1.4 kg/MT aluminum and sulfur oxides of 12 kg/MT
aluminum result in this situation.
Control of fluoride, organic and particulate emissions at the Carbon
Anode Bake Plant was assumed to be by electrostatic precipitator,
a venturi scrubber and a chamber scrubber in series. There was no
data quantitatively available on the organic and particulate emissions
which result from this control system.
The water pollution control technology needed to achieve 1977 standards
involved: (1) Segregation of fluoride-containing waste for treatment
including anode bake furnace scrubber water, water resulting from
cryolite recovery from potlinings, used cathode disposal liquor and
runoff from used-cathode storage area. (Scrubber water from potlines
and potroom did not exist in our case because dry scrubbing was
used. However, the water standards are the same for any air pollution
control system.); (2) Recycling clarified liquor after precipitation
of calcium fluoride cryolite; (3) Minimizing the volume of the bleed
stream; and (4) Providing a holding pond or lagoon if necessary to
accomplish further settling of solids in the bleed stream and providing
aeration of the lagoon to accomplish oxidation of oil and grease,
if necessary.(6S)
The standards for 1977 are written for fluorides, suspended solids,
and oil and grease. The other on-site water effluents shown in
Table 41 are assumed to be uncontrolled and are an average from
plants sampled in the effluent guidelines study.
It can be seen from Table 41 that although there are significant
pollution problems at the smelter site, most of the impacts in the
categories of atmospheric emissions, and solid wastes result from
the generation of electricity and the mining of coal for fuel in
electrical generation. It is clear, therefore, that the extremely
high electrical requirement is the overriding environmental concern
in aluminum smelting operations,
The emission factors for electrical generation--which are used for
every system in this study--are based on a national average mix of
fuels for electrical generation. It is true that the aluminum
industry uses a relatively high proportion of hydroelectric power.
86
-------
TABLE 41. MODULE SUMMARY SHEET FOR PRIMARY ALUMINUM SMELTING
Basis: 1 metric ton of wrought or cast
On
MATERIAL INPUTS (kilograms)
Alumina 1
Cryolite
Aluminum Fluoride
Fluorspar
WATER DISCHARGED (liters)
Process 145
Mine Drainage
AIR EMISSIONS (grams)
Particulates 3
Sulfur Oxides 19
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides 9
Aldehydes
Organics
Fluorides 1
WATER POLLUTANTS (grams)
Suspended Solids 1
Dissolved Solids 11
BOD
COD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride 1
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
Coal (kg)
Equivalent kcal 1,
Liquid Hydrocarbon
fuels (.&)
Equivalent kcal
Natural Gas (m3)
Equivalent kcal 11
Electricity (kw-hr)
Equivalent kcal 41
Other Fuels kcal
Carbon electrodies (kg)
Equivalent kcal 4
Total kilocalories 58
Site
,930
10
40
50
,500
,980
,449
103
799
,264
59
77
,050
,500
,670
—
660
250
--
67
—
—
3
,000
25
190
290,000
7.5
74,000
1,200
,220,000
13,800
,082,600
28,000
595
,750,000
,444,600
aluminum ingot
Off Site
7,086
1,025
11,050
59,867
23,318
58,370
96,327
228
35
95
6,312
129
364
67
14
8
8
13
27,929
1,195
801,000
Total Source
46
1,930
10
40
50
17
152,586
1,025
11,67
15,030
79,316
23,321
59,169
105,591
287
112
1,050
65
1,595
17,982
129
1,024
317
14
75
8
13
3
1,000
68
27,929
1,220
21
59,245,600
87
-------
It is our judgment, however, that a study such as this should not
distinguish between different "kinds" of kilowatt hours, since if
the hydroelectric power were not used by the aluminum industry,
it would be available as an alternative to power generated with
fossil fuels. In cases where electricity is generated by the
aluminum companies for captive use in their plants, the power is
not included in the electrical energy category. Rather, the fuels
used to generate that power are included separately.
Aluminum from Recycled Materials
There is essentially no difference between secondary aluminum metal
and primary metal as long as the composition is the same. However,
there is a problem in producing secondary metal having the same degree
of purity as primary metal. The basis of this problem is that it is
difficult and uneconomic to remove metallic impurities, except for
magnesium, from aluminum by the usual melting and refining. Hence,
the quality and type of aluminum scrap used largely determines the
alloy produced by the scrap consumer. The essential consequence of
these technological limitations is that the use of secondary aluminum
is usually limited to the manufacture of castings.
Aluminum end products are classified into two main classes: (a) wrought
products such as sheet, plate, rolled and continuous cast rod and bars,
wire, extrusions and forging; and (b) castings, including sand,
permanent mold and die castings. In general, wrought products require
a lower degree of impurities than cast products because common
alloying agents such as copper and silicon reduce the ductility of
aluminum. However, if scrap from one type of wrought product can be
segregated, the scrap can be remelted into ingots which can be used
to produce more of that wrought product.
Aluminum scrap from autos and aluminum cans was assumed in this
study to be used in three ways by the aluminum industry: (1) Aluminum
cans remelted into wrought ingots that may be used to produce more
cans, (2) Aluminum scrap from municipal solid wastes remelted into a low
magnesium content casting alloy and, (3) Aluminum scrap from junk
autos remelted into a low magnesium content casting alloy.
According to secondary aluminum sources, the recovery rate of aluminum
is approximately 95% from heavy scrap (auto scrap) and 87% from scrap
cans.(69) The scrap inputs for all the secondary aluminum modules
reflect these figures. It was also assumed that the amount of flux
required for melting is 10% of the scrap charge. Although fluxes
usually average 47.5% NaCl, 47.5% KC1 and 5% cryolite, it was assumed
in this study that the flux is composed only of NaCl (rock salt).
88
-------
Aluminum Cans to Wrought Ingots
Obsolete aluminum cans can be remelted into wrought aluminum ingots
which can be used to produce more cans. Figure b shows the system
assumed necessary in this case. Cans from separate can collection
or from municipal solid waste were assumed to be remelted by a
secondary aluminum smelter. All of the modules in this system,
except the secondary aluminum smelter, have been described in earlier
sections.
Secondary Aluminum Smelting: Wrought Ingots. Aluminum cans may
be remelted into wrought ingots by either a primary aluminum smelter
or a secondary aluminum smelter. In either case, the environmental
impacts are considered to be the same. Upon arrival of the shredded
cans at the smelter, the scrap is unloaded to storage, retrieved from
storage, delacquered in a furnace, and then remelted, blended and
refined, and cast into wrought ingots. The energy requirements shown
in Table 42 are for the above steps. It can also be seen from this
table that only 4 kg of chlorine are required to produce one metric
ton of secondary aluminum. This small chlorine requirement is due
to the fact that chlorine is only required for degassing the
aluminum. It was assumed that no chlorine is required to "demag"
the aluminum because the scrap cans are being used to produce more
cans.
The on-site air emissions shown in Table 42 result from the combustion
of fuels to fire the delacquering and remelting furnaces, particulates
from these furnaces and chlorides from the degassing operation. The
scrap cleaning furnace and the melting furnace are assumed to emit
7.3 and 2.15 kilograms of particulates per metric ton of secondary
aluminum produced.t11) Both these sources were assumed to be
controlled by baghouses or wet scrubbers with a 90% efficiency of
control.(70,71) Degassing operations were assumed to emit 2 kilograms
of chlorides per metric ton of aluminum,(^J which can be controlled
with a 90% efficiency by alkaline wet scrubbers.(^OJ
The on-site water effluents shown are those which will result when
the 1977 Water Effluent Standards are met.C65) These standards for
discharges from fume scrubbing processes are said to be achievable
by neutralization, precipitation, supernatant recycle and solid
fluoride removal.
The on-site solid wastes were determined by performing a material
balance on the input materials.
89
-------
FIGURE 6. SHEET ALUMINUM PRODUCTION FROM ALUMINUM CANS
SYSTEM A2 INCLUDES MUNICIPAL SOLID WASTE RECOVERY
SYSTEM A3 INCLUDES SEPARATED CAN RECOVERY
Municipal
Solid Waste
Recovery
Separated
Can
Recovery
Chlorine
Production
(1020)
4
Rock
Salt
Production
1155
116
Secondary
Aluminum
Smelter
1000
Wrought
Aluminum
Ingots
Numbers are kilograms of product required to produce one metric ton of aluminum.
Number in parentheses is kilograms of rock salt required to produce one metric ton of chlorine.
-------
TABLE 42. MODULE SUMMARY SHEET FOR SECONDARY ALUMINUM SMELTING
(CANS TO SHEET)
Basis: 1 metric ton wrought
MATERIAL INPUTS (kilograms)
Scrap aluminum
Fluxes
Chlorine
WATER DISCHARGED (liters)
Process
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
Liquid Hydrocarbon
Fuels ( ^)
Equivalent kcal
Natural Gas (m3)
Equivalent kcal 1
Electricity (kw-hr)
Equivalent kcal
Total kilocalories 1
aluminum
On Site Off Site
1,155
116
4
3,344 479
1,007 50
200
1,685
125 4,483
722 4,994
9 1
22 1
200
175
500 12
340
0.02
0.004
0.008
0.009
53
273 2
1.05
9,800
195
,820,000
28
83,400
,913,200 87,700
Total Source
69
1,155
116
4
17
3,823
11,70,71
1,057
200
1,685
4,608
5,716
10
23
200
65
175
512
340
0.02
0.004
0.008
0.009
53
275
46
2,000,900
91
-------
Aluminum Scrap from MSW to a Low Mg Casting Alloy
Figure 7 shows the combination of modules necessary to produce a
low magnesium cast aluminum ingot from municipal solid waste. The
primary difference between this system and the one considered in
the preceding section is the large amount of chlorine required
for demagging operations.
Secondary Aluminum Smelting: High Mg Scrap to Low Mg Casting Alloy.
If the aluminum scrap received from the municipal solid waste
recovery center is of the composition that it is impossible to
further segregate the scrap so that wrought aluminum can be produced,
then the magnesium content must be reduced from 4.5% to an acceptable
limit of 0.1% in casting alloys.C?2) Approximately 4 kg of chlorine
are required to remove 1 kg of magnesium, 3 kg of which react with
the magnesium and 1 kg of which reacts with aluminum.(70)
From Table 43, it can be seen that 180 kg of chlorine were assumed
to be necessary to produce one metric ton of a low magnesium casting
aluminum ingot. Since approximately 500 kg of particulate emissions
result for each metric ton of chlorine used, (73) and these emissions
are controlled with a 90% efficiency,(70) the chlorine emissions are
9 kg/MT of aluminum.
It can also be seen from Table 43 that the water effluents have
increased when compared to those of the preceding section. This
increase is due to the fact that the effluent guidelines are written
in terms of the amount of chlorine used.
Aluminum Scrap from Junk Autos to a Low Mg Casting Alloy
Figure 8 shows the combination of modules necessary to produce a low
magnesium cast aluminum ingot from aluminum scrap from junk autos.
This system differs from the two preceding aluminum recycle systems
in the amounts of scrap, chlorine, and fluxes required.
Secondary Aluminum Smelting: Normal Operations. The aluminum received
from auto scrap processors was assumed to be of such a quality that it
contains only 0.5% of magnesium which needs to be removed. From Table
44, it can be seen that 20 kilograms of chlorine are required per metric
ton of aluminum produced. This chlorine use results in lokg of chlorine
92
-------
FIGURE 7. CAST ALUMINUM PRODUCTION FROM MUNICIPAL SOLID WASTE
SYSTEM A4
10
Municipal
Solid Waste
Recovery
Chlorine
Production
(1020)
184
Rock Salt
Mining
1155
180
116
Secondary
Aluminum
Smelter
1000
Low Magnesium
Cast Aluminum
Ingots
NUMBERS ARE KILOGRAMS OF PRODUCT REQUIRED TO PRODUCE ONE METRIC TON OF ALUMINUM.
NUMBER IN PARENTHESES IS KILOGRAMS OF ROCK SALT REQUIRED TO PRODUCE ONE METRIC TON OF CHLORINE.
-------
TABLE 43. MODULE SUMMARY SHEET FOR SECONDARY ALUMINUM SMELTING
(CANS TO LOW Mg
ALLOY)
Basis: 1 metric ton of cast aluminum ingot
MATERIAL INPUTS
Scrap Aluminum
Fluxes
Chlorine
WATER DISCHARGED
Process Water
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Process
ENERGY CONSUMPTION
Liquid Hydrocarbon
Fuels (-£)
Equivalent kcal
Natural Gas (m3)
Equivalent kcal
Electricity (kw-hr)
Equivalent kcal
Total kilocaiories
On Site Off Site
1,155
116
180
3,344 479
1,007 50
200
1,685
125 4,483
722 4,994
9 1
22 1
9,000
7,875
22,500 12
15,300
0.9
0.18
0.36
53
4U5 2
1.05
9,800
195
1,820,000
28
83,400
1,913,200 87,700
Total Source
69
1,155
116
180
17
3,823
11,70,71
1,057
200
1,685
4,608
5,716
10
23
9,000
65
7,875
22,512
15,300
0.9
0.18
0.36
53
407
46
2,000,900
94
-------
FIGURE 8. CAST ALUMINUM PRODUCTION FROM AUTO SCRAP
SYSTEM AS INCLUDES SHREDDING
SYSTEM A6 INCLUDES BALING
to
in
Auto Hulk
Processing
(.71)
.75 v
/
Auto Scrap
Processor
t4
-------
TABLE 44. MODULE SUMMARY SHEET FOR SECONDARY ALUMINUM SMELTING
(AUTO SCRAP)
Basis: 1 metric ton cast aluminum ingot
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes
Chlorine
WATER DISCHARGED (liters)
Process Water
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organ ics
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Process
On Site
1,050
105
20
3,344
1,007
125
722
9
22
1,000
875
2,500
1,700
0.1
0.02
0.04
0.045
170
Off Site
479
50
200
1,685
4,483
4,994
1
1
12
53
2
Total Source
69
1,050
105
20
17
3,823
11,70,71
1,057
200
1,685
4,608
5,716
10
23
1,000
65
875
2,512
1,700
0.1
0.02
0.04
0.045
53
172
ENERGY CONSUMPTION
Liquid Hydrocarbon
Fuels ( X-) 1.05
Equivalent kcal 9,800
Natural Gas (m3) 195
Equivalent kcal 1,820,000
Electricity (kw-hr) 28
Equivalent kcal 83,400
Total kilocalories 1,913,200 2,000,900
96
-------
emissions before control and 1 kg of chlorine emissions after 90%
control. The water effluents shown in Table 44 result if 1977
water standards, which are based on chlorine use, are met. The
on-site solid wastes shown in this table were determined by per-
forming a mass balance on input and output materials.
Aluminum Systems Synthesis
This section summarizes the environmental impacts of six systems which
produce wrought and/or cast aluminum products. The total impacts for
each system were determined using the detailed information contained
in the module summaries and known yield data, the kilograms of output
from each module necessary to produce one metric ton of aluminum as
shown in the detailed flow charts (Figures 5, 6, 7 and 8).
Aluminum Production from Virgin Materials
Figure 5 shows the processes necessary to produce aluminum from virgin
materials. This figure also shows the quantity of material from each
module which is required to produce one metric ton of wrought or cast
aluminum ingots. Table 45 shows the environmental impacts which result
from the individual modules in the production of one metric ton of
aluminum. The totals shown in the last column of this table are the
cumulative impacts of the individual modules, the impacts of the whole
system. In the case where an intermediate product, such as alumina is
produced, it is shown as an output from alumina production and an input
to the primary aluminum smelter. The net effect is that alumina is not
treated as a material input to the system, rather the bauxite which was
consumed to produce the alumina is the material input to the system.
It can be seen from Table 45 that primary aluminum smelting accounts
for most of the air emissions, water pollutants and solid wastes which
result from the production of aluminum by System Al. Primary aluminum
smelting also accounts for 79% of the total energy and 95% of total
water consumed by the system.
Wrought Aluminum Production from Aluminum Cans
Figure 6 shows the modules and the quantity of output from the modules
which are necessary to produce one metric ton of wrought aluminum ingots
from used aluminum cans. It can be seen from this figure that two sys-
tems are considered as sources of aluminum cans: System A2 which includes
municipal solid waste recovery and System A3 which includes separated
aluminum can recovery.
97
-------
Table 45 SUMMARY SHEET FOR ALUMINUM PRODUCTION USING VIRGIN MATERIALS (SYSTEM AI)
Basis I metric ton of aluminum ingot• wrought or cast
Limestone
Quarrying
Lime
Production
Rock Salt
Mining
Caustic Soda
Production
Primary
Alumina Aluminum
Production Smelting
Total
MATERIAL INPUTS
Limestone
Lime
Rock Salt
Caustic Soda
Bauxite
Alumina
Aluminum Fluoride
Cryolite
Fluorspar
WATER DISCHARGED (liters]
Process 7
Mine Drainage 37
AIR EMISSIONS
Particulates 316
Sulfur Oxides 5
Carbon Monoxide 26
Hydrocarbons 11
Nitrogen Oxides 19
Aldehydes 0
Organics 1
Fluorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
BOD
COD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Fluoride
SOLID WASTES (kilograms)
Overburden 1
Process 9
115.8
- 57.9
57.9
139.7
- 137
137
5,134
- 1,930
67
2
385
216
48
80
153
1
1
309
12
IS
59
55
102
1
2
578
19
206
1,158
246
590
1,298
4
1
493
119
6,226
8
47
12
25
20
518
23
77
13,605
571
21
69
10
2
2
2
203
589
1,930
40
10
50
152,586
1,025
16,978
652
2,377
4,210
5,904
183
20
3,727
7,241
8,606
22,689
25,561
135
129
15,030
79,316
23,321
59,169
105,591
287
112
1.050
1,595
17,982
129
1,024
317
14
75
8
13
3
1,000
27,929
1,220
115.8
139.7
5,134
40
10
50
160,266
1.091
36.654
88,603
34,684
86,804
138,628
611
265
1.050
1.595
18.567
150
1,093
327
14
77
10
15
3
1.000
28,800
15,478
ENERGY (kilocalories)
6,700
77,400
52,200
807,600
2,458,700 12,182,400
59,245,600
74,850,600
-------
Tables 46 and 47 show the environmental impacts which result from the
production of one metric ton of wrought aluminum using scrap aluminum
cans by Systems A2 and A3, respectively. It may be seen from these
tables that the secondary aluminum smelter is the primary cause of most
of the environmental impacts from these systems.
Cast Aluminum Production from MSW Aluminum Scrap
Figure 7 shows the modules and the quantity of output from the modules
which are necessary to produce one metric ton of cast aluminum ingots
from municipal solid waste. Table 48 summarizes the environmental
impacts which result from the production of one metric ton of cast
aluminum ingots by this system. It can be seen from this table that
the secondary aluminum smelter is the greatest source of impacts from
this system. However, chlorine production is also a large source of
air emissions and solid wastes due to the large electrical require-
ments for the process.
Cast Aluminum Production from Auto Scrap
Figure 8 shows the modules and the quantity of output from each module
which are necessary to produce one metric ton of cast aluminum from
auto scrap. It can be seen from this figure that a stripped auto hulk
may either be processed into scrap by a shredding operation (System AS)
or a baling and incineration operation (System A6). Tables 49 and 50
show the environmental impact which results from the production of one
metric ton of cast aluminum by these systems. It may be seen from these
tables that secondary aluminum smelting is the primary source of impacts
from these systems.
Environmental Impact Comparison
Six systems have been considered for the production of aluminum ingots
in this study. However, it was seen in the previous section that these
six systems could be classified in four groups:
I. Aluminum Production from Virgin Materials (System Al)
II. Wrought Aluminum Production from Aluminum Cans (Systems A2 and A3)
III. Cast Aluminum Production from MSW (System A4)
IV. Cast Aluminum Production from Auto Scrap (Systems A5 and A6)
Since the environmental impacts of these systems does not very much
within a group, the most meaningful comparisons of systems using virgin
and recycled materials will be realized if System Al is compared with
Systems A2 and A3, with System A4 and with Systems AS and A6.
99
-------
Table 46. Summary Sheet for Wrought Aluminum Production Using Scrap Aluminum
Cans from MSWR System A2
Basis: 1 metric ton of
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes (NaCl)
Chlorine
WATER DISCHARGED [liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Processing
Post Consumer - 1
Wrought
MSWR
35
9
353
596
690
422
919
10
21
55
240
299
,444
Aluminum
Chlorine
Production
4
- 4
17
1
6
34
7
17
38
3
15
1
Secondary
Rock Salt Aluminum
Mining Smelter
1,155
116
4
266 3,823
11 1,057
13 200
51 1,685
47 4,608
88 5,716
1 10
2 23
200
175
5 512
340
0.02
0.004
0.008
0.009
21 53
17 275
Total
1,155
120
4,141
10
1,427
843
2,433
5,096
6,761
21
46
200
175
575
340
0.02
0.004
0.008
0.009
329
592
1,444
ENERGY CONSUMPTION
(Thousand kilocalories)
491.2
23.6
44.9 2,000.9
2,560.6
100
-------
Table 47. Summary Sheet for Wrought Aluminum Production Using Scrap Aluminum
Cans Collected Separately System A3
Basis: 1 metric ton of Wrought Aluminum
Separated
Can
Chlorine
Production
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes (NaCl)
Chlorine
WATER DISCHARGED (liters)
Process 27
Mine Drainage 7
AIR EMISSIONS (grams)
Particulates 99
Sulfur Oxides 468
Carbon Monoxide 662
Hydrocarbons 357
Nitrogen Oxide 776
Aldehydes 9
Organics 21
Chloride
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids 42
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Processing
Post-consumer
182
8
- 1,155
ENERGY CONSUMPTION
(Thousand kilocalories) 402.2
- 4
17
1
6
34
7
17
38
15
1
23.6
Rock Salt
Mining
266
21
17
Secondary
Aluminum
Smelter
1,155
116
4
3,823
53
275
Total
1,155
120
4,133
8
11
13
51
47
88
1
2
1,057
200
1,685
4,608
5,716
10
23
200
1,173
715
2,405
5,029
6,618
20
46
200
175
512
340
0.02
0.004
0.008
0.009
175
562.
340
0.02
0.004
0.008
0.009
44.9 2,000.9
271
301
1,155
2,471.6
101
-------
TABLE 48. SUMMARY SHEET FOR CAST ALUMINUM INGOTS BY A SECONDARY SMELTER USING
SCRAP ALUMINUM CANS FROM MSWR; SYSTEM A4
Basis: 1 metric ton of
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes (NaCl)
Chlorine
WATER DISCHARGED (liters)
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates
Sulfur Oxides
Carbon Monoxide
Hydrocarbons
Nitrogen Oxide
Aldehydes
Organics
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Processing
Post- consumer - 1
cast
MSWR
35
9
353
596
690
422
919
10
21
55
240
299
,444
aluminum
Chlorine
Production
184
- 180
760
25
270
1,522
324
775
1,705
5
1
2
156
680
30
Secondary
Rock Salt Aluminum
Mining Smelter
1,155
166
180
665 3,823
27 1,057
35 2PO
127 1,635
117 4,508
220 5,716
2 10
4 23
9,000
7,875
12 22,512
15,300
0.9
0.18
0.36
0.41
54 53
42 407
Total
1,155
300
5,283
34
1,707
2,351
2,826
5.922
8,560
27
49
9,000
7,877
22,735
15,300
0.9
0.18
0.36
0.41
1,027
778
- 1,444
ENERGY CONSUMPTION
(Thousand kilocalories)
491.2 1,061.0
112.2
2,000.9
3,665.3
102
-------
TABLE 49. SUMMARY SHEET FOR CAST ALUMINUM INGOTS BY
Basis 1 metric ton of cast aluminum
Auto Hulk
Processor
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes (NaCl)
Chlorine
WATER DISCHARGED
Process
Mine Drainage
AIR EMISSIONS (grams)
Particulates 12
Sulfur Oxides 20
Carbon Monoxide 1,146
Hydrocarbons 248
Nitrogen Oxide 293
Aldehydes 7
Organics 14
Chlorides
WATER POLLUTANTS (grains)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Process
Post-consumer - 1,149
A SECONDARY
Auto Scrap
Processor
9
2
56
259
555
214
460
21
19
15
67
102
SMELTER USING ALUMINUM AUTO SCRAP
Chlorine Rock Salt
Production Mining
20
- 20
84 277
3
30 11
169 14
36 53
86 49
190 92
1 1
2
17
76 22
3 18
FROM A SHREDDER : SYSTEM AS
Secondary Aluminum
Smelting
1,050
105
20
3,825
1,057
200
1,685
4,608
5,716
10
23
1,000
875
2,512
1,700
0.1
0. 2
0.04
0.045
53
172
-
Total
1,050
125
4,193
5
1,166
662
3,475
5,205
6,751
40
58
1,000
875
2,544
1,700
0.1
0 02
0.04
0.045
21S
295
1,149
ENERGY CONSUMPTION
(Thousand kilocalories)
61.9
230.6
117.9
46.8
2,000.9
2,458 1
-------
PABLF 50 SUMMARY SHEET FOR CAST ALUMINUM INGOTS
Basis 1 metric ton of cast aluminum
Auto Hulk
Processor
MATERIAL INPUTS (kilograms)
Scrap Aluminum
Fluxes (NaCl)
Chlorine
WATER DISCHARGED
Process
Mine Drainage
AIR EMISSIONS (grams)
Participates 12
Sulfur Oxides 20
Carbon Monoxide 1,146
Hydrocarbons 248
Nitrogen Oxide 293
Aldehydes 7
Organics 14
Chlorides
WATER POLLUTANTS (grams)
Suspended Solids
Dissolved Solids
Chloride
Cyanide
Cadmium
Lead
Manganese
SOLID WASTES (kilograms)
Overburden
Process
Post-consumer - 1,149
BY A SECONDARY
Auto Scrap
Processor
45
2
563
184
671
592
347
32
156
34
53
17
SHELTER USING ALUMINUM AUTO SCRAP
Chlorine Rock Salt
Production Mining
20
- 20
84 277
3
30 11
169 14
36 53
86 49
190 92
1 1
2
17
76 22
3 18
FROM A BALER; SYSTEM A6
Secondary Aluminum
Smelting
1,050
105
20
3,825
1,057
200
1,685
4,608
5,716
10
23
1,000
875
2,512
1,700
0.1
0.02
0.04
0.045
53
172
-
Total
1,050
125
4,231
5
1,673
587
3,591
5,497
6,638
51
195
1,000
875
2,573
1,700
0.1
0.02
0.04
0.045
204
210
1,149
ENERGY CONSUMPTION
(Thousand kilocalories)
61 9
415.3
117 9
46.8
2,000 9
2,64T.3
-------
System Al vs Systems A2 and A3
Table 51 shows the environmental impacts which result from the proiluct i on
of one metric ton of wrought aluminum from virgin materials (System Al)
and from scrap aluminum cans (Systems A2 and A3). It may be seen
from this table that Systems A2 and A3 reduce raw materials consumed
by 5370 kilograms (98%), water discharged by at least 157,206 liters
(97%), and energy consumption by at least 72,270,000 kilocalories
(97%) when compared to System Al.
It can also be seen from Table 51 that Systems A2 and A3 also reduce
air emissions by 370.4 kilograms (96%) as compared to System Al. The
only increase in air emissions produced by Systems A2 and A3 are the
chloride emissions. However, the environmental impact of 200 grams
of chlorides is no worse than 1050 grams of fluoride. From Table 51
it can be seen that water pollutants are reduced 21.76 kilograms
(95%) by Systems A2 and A3. Again, there are increases in some
pollutants. However, these increases are very minimal. Solid wastes
are reduced from 44,278 kilograms for System Al to -523 or -583 kilo-
grams for Systems A2 and A3. Therefore, instead of producing solid
wastes, Systems A2 and A3 remove solid waste from the environment.
In summary, wrought aluminum production from scrap aluminum cans has
minimal environmental impacts when compared to wrought aluminum pro-
duction from virgin materials. A comparison of aluminum production
using scrap aluminum cans from MSW (System A2) to scrap aluminum cans
collected separately (System A3) shows the separated can collection
to be slightly superior.
System Al vs System A4
Table 51 shows the environmental impacts which result from the production
of one metric ton of cast aluminum from virgin materials (System Al) and
from municipal solid waste scrap (System A4). It can be seen from this
table that System A4 reduces raw material consumption by 5190 kilograms
(95%), water discharged by 156040 liters (97%), energy consumption by
71,165,300 kilocalories (95%); and solid wastes by 43,917 kilograms
(99%) when compared to System A4.
It can also be seen from Table 51 that System A4 reduces air emissions
by 356,821 grams (92%). However, System A4 produces 9000 grams of
chlorides at the site of the secondary aluminum smelter which is usually
located in urban areas. Water pollutants are increased 23,063 grams
(101%) by System A4 and 15,300 grams of this increase are chloride.
In summary, it can be seen that cast aluminum production from MSW scrap
(System A4) greatly reduces raw materials consumption, water discharged,
energy consumption, solid wastes and air emissions when compared to cast
aluminum production from virgin materials (System Al). However, increases
105
-------
TABLE 51. COMPARISON OF ENVIRONMENTAL IMPACTS FOR THE PRODUCTION OF ALUMINUM USING VIRGIN OR RECYCLED MATERIALS
Basis: 1 Metric Ton of Aluminum, Wrought and/or Cast Ingots
A2 A3 A4 AS A6
Virgin Materials to MSW Scrap to Separated Aluminum MSW Scrap to Shredder Scrap Baler Scrap
Wrought or Cast Ingots Wrought Ingots Cans to Wrought Ingots Cast Ingots to Cast Ingots to Cast Ingots
MATERIAL INPUTS (kilograms)
Total Raw Materials
Bauxite
Limestone
NaCl
Aluminum Fluoride
Cryolite
Fluorspar
Scrap
WATER DISCHARGED [liters)
Process
Mine Drainage
AIR EMISSIONS (grans]
Participates
Sulfur Oxides
Carbon Monoxides
Hydrocarbons
Nitrogen Oxides
Aldehydes
Organics
Fluorides
Chlorides
WATER POLLUTANTS
Suspended Solids
Dissolved Solids
800
COD
Oil and Grease
Iron
Phenols
Sulfide
Ammonia
Cyanide
Cadmium
Lead
Manganese
Fluoride
Chloride
SOLID WASTES (kilograms)
Overburden
Processing
Post-consumer
5,489.5
5,134
115.8
139.7
40
10
SO
161,357
160,266
1,091
387,263
36,654
88,603
34,648
86,804
138,628
611
265
1,050
22,851
1,595
18,567
150
1,093
327
14
77
10
IS
3
1,000
44,278
28,800
15,478
120
120
1,155
4.151
4.141
10
16.827
1,427
843
2,433
5,096
6,761
21
46
200
1,090
175
575
0.02
0.004
0.008
0.009
340
- 523
329
592
- 1,444
120
120
1,155
4,141
4,133
8
16,206
1,173
715
2,405
5,029
6,618
20
46
200
1,077
175
562
0.02
0.004
0.008
0.009
340
- 583
271
301
- 1,155
300
300
1,155
5,317
5,283
34
30,442
1,707
2,351
2,826
5,922
8,560
27
49
9,000
45,914
7,877
22,735
0.9
0.18
0.36
0.41
15,300
361
1,027
778
- 1,444
125
125
1,050
4.198
4,193
5
18,357
1.166
662
3,475
5,205
6.751
40
58
1.000
5,119
875
2,544
0.1
0.02
0.04
0.045
1,700
632
218
295
- 1,145
125
125
1,050
4,236
4,231
5
19,232
1,673
587
3.591
5,497
6,638
51
195
1,000
5,148
875
2,573
0.1
0.02
0.04
0.045
1,700
- 735
204
210
-1,149
bNERGY CONSUMPTION
(Thousand '..ilocalories) 74,830.6 2,560.6 2,471 6 3,665 3 2,458 1 2,t>42 S
-------
in chloride emissions and water pollutants are two problems associated
with System A4. Although it would be more desirable to produce cast
aluminum from MSW scrap than virgin materials, MSW scrap can be used
with less impacts by System A2 if converted into wrought aluminum,
and cast aluminum ingots can be produced from auto scrap by Systems
AS and A6 with fewer impacts.
System Al vs Systems AS and A6
Table 51 shows the environmental impacts which result from the production
of one metric ton of cast aluminum from virgin materials (System Al) and
from auto scrap (Systems A5 and A6). It can be seen from this table that
Systems AS and A6 reduce raw materials consumed by 5,365 kilograms (98%),
water discharged by at least 157,121 liters (97%), and energy consumed
by at least 72,188,000 kilocalories (96%).
Systems AS and A6 also effect a net removal of 632 to 735 kilogramsof
solid wastes from the environment while System Al produces 44,278
kilograms of solid waste. It can be also seen from Table 51 that air
emissions are reduced by at least 368 kilograms (95%) by Systems A5
and A6, while water pollutants are reduced at least 17.7 kilograms
(77%). The chloride air and water emission from Systems AS and A6
compare to the fluoride emissions from System Al.
In summary, cast aluminum production from auto scrap (Systems A5 and A6)
results in minimal environmental impacts when compared to cast aluminum
production from virgin materials (System Al). The comparison of Systems
AS and A6 with each other shows the two systems to have roughly equiva-
lent impacts.
Pollution Control Costs for Aluminum
An assumption basic to this study was that 1975 Air Standards and 1977 Water
Standards would be met. Air emissions and water effluents were reported
with this premise in mind. However, there is a real dollar cost to
industry in meeting these standards. When sufficient data were avail-
able, cost estimates for meeting the standards were developed for each
module. However, there were not sufficient data available to determine
the total cost of meeting the standards for each system studied. There-
fore, in order to keep the cost data comparable for all the systems,
cost estimates were only developed for the direct cost to the primary
and secondary aluminum industries in meeting 1975 Air Standards and
1977 Water Standards.
Table 52 summarizes the pollution control costs for aluminum production.
The costs shown in this table are the net annual costs per metric ton
107
-------
Table 52. Pollution Control Costs for Aluminum: Net Annual Cost
ALUMINA REFINING
Total
Air
Water
PRIMARY ALUMINUM SMELTING
Total
Air
Prebake Cell
Anode Bake Furnace
Water
SECONDARY ALUMINUM
SMELTING
(Total)
Air
Water
Cooling
Scrubber water
Unit C^sts
$/MT of alumina
0.39-0.90
0.00
0.39-0.90
$/MT of aluminum
10.16-13.59
7.31-10.74
2.50-4.00
2.85
$/MT of aluminum
4.98-10.10
3.28-8.40
0.20
1.50
Cost to System Al
$/MT of aluminum
0.75-1.74
10.16-13.59
Cost to Systems A2,
A3, A4, AS and A6
$/MT of aluminum
4.98-10.10
Source
65
62
65,75
76
65
TOTAL
10.91-15.33
4.98-10.10
-------
of aluminum produced. The net annual cost per metric ton of aluminum
was computed by summing the annual operating costs which include costs
for power, materials, labor, maintenance, taxes, insurances and inter-
est; with the depreciation on the capital investment, and then substract-
ing the credit for returned materials. The unit costs shown in column
1 of Table 52 are costs for the types of pollution control equipment
which were previously discussed in the module descriptions.
It can be seen from Table 52 that the control costs for System Al
which produces aluminum from virgin materials are $10.91 to 15.33
per metric ton of aluminum. The pollution control costs for Systems
A2, A3, A4, AS, and A6 which produce aluminum from obsolete scrap are
$4.98 - 10.10. Systems such as A2 and A3 which use a minimum amount
of chlorine would be in the low end of the range while System A4
which uses a large amount of chlorine would be in the high end of the
range.
109
-------
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4. "Study of the Economic Viability of Reclaiming Tin Cans from
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110
-------
15. Stripping, Sierra Club Publ., 1972.
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18. Reid, G, W, et al%J "Evaluation of Waste Waters from Petroleum
and Coal Processing", Oklahoma University, Norman. EPA R2 72 001,
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19. "Atmospheric Emissions from Petroleum Refineries, A Guide for
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20. Craft, B. C., W, R, Holden and E. D. Graces, Jr., Well Design:
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21. 1967, Census of Mineral Industries, U. S. Bureau of Census,
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24. 1967 Census of Manufactures, Petroleum and Coal Products, U. S.
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27. Statistical Abstract of the United States, 1970, United States
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Ill
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29. United States Department of Commerce Census of Transportation,
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31. Dean, D. C., and J. W. Steiner, "Dismantling a Typical Junk
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32. Al-jon Corp., Attumwa, Iowa, Personal Communication (May, 1973).
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for Recycling Metal, Natl. Assoc. of Secondary Material
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34. Chindgren, C. J., et al., "Construction, and Testing of a Junk
Auto Incinerator, Bureau of Mines, Salt Lake City, Utah, Salt
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35. Newell, S., "Technology and Economics of Large Shredding
Machines", Proc. of the Third Mineral Waste Utilization Sym.,
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36. Hassell, E. W. and E. R. Killam, "Auto Wrecking Industry:
Problems arid Prospects," Scrap Age, 27 (2): 202-267 (Feb., 1970).
37. Personal Communication with Newell, S., Newell Manufacturing
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45. "Materials Recovery System", National Center for Resource
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Aluminum Beverage Can", Aluminum Co. of America, Pittsburg,
Pa. (1973).
47. Vandegrift, A. E., et al., "Particulate Pollution System
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48. Minerals Yearbook. Vol. I. Metals, Minerals and Fuels, U. S.
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49. "Limes and Limestone," Kirk-Othmer Encyclopedia of Chemical
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56. McGannon, H. E., (Ed.), The Making, Shaping and Treating of
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(1964).
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113
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59. George, F. B., "The Effect of the Various Steelmaking
Processes on the Energy Balances of Integrated Iron and
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60. "Management of Water in the Iron and Steel Industry", ISI
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61. Stone, J. K., "Increasing Scrap Usage by the L-D Process-
Theory, Practice and Prospects", Iron and Steel Engineer,
40, No. 6, p. 67-78, June, 1963.
62. "Technical Report on Electric Arc Steel Furnaces", (draft)
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63. "Electric Furnace Proceedings", American Institute of Mining,
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64. Shreve, N. and R. Nories, Chemical Process Industries,
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65. "Development Document for Effluent Limitations Guidelines
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66. Brevoed, J. G., et al., "Energy Expenditures Associated
with the Production and Recycle of Metals", Oak Ridge
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67. "Primary Aluminum Smelters", Draft Technical Report, EPA,
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68. McClair, R. S., and G. V. Sullivan, "Beneficiation of
Aluminum Plant Residues," Bureau of Mines Report of Investigations
6219 (1963).
69. Ginsburg, T., Keystone Metal Co., Pittsburg, Pa., Personal
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70. Tomany, J. P., "A System for Control of Aluminum Chloride
Fumes", Journal of the Air Pollution Control Association, 19,
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71. Lauber, J. D., et al., "Air Pollution Control of Aluminum
and Copper Recycling Processes", Pollution Engineering, 5,
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114
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72. Ginsburg, T. "Technology and Research in the Secondary
Aluminum Smelting Industry", Effective Technology for
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73. McCabe, L. C., "Atmospheric Pollution", Industrial and
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in the Integrated Iron and Steel Industry", Battelle Memorial
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of Air Programs, EPA Preliminary Draft (April, 1973).
76. Bender, R. J., "Air Pollution Control: Its Impact on the
Metal Industries", Power, p. 56-60 (April, 1972).
115
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