&EPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/625/R-92/009
September 1992
Guides to Pollution
Prevention
Metal Casting and
Heat Treating Industry
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EPA/625/R-92/009
September 1992
Guides to Pollution Prevention
The Metal Casting and Heat Treating Industry
Risk Reduction Engineering Laboratory
and
Center for Environmental Research Information
Office of Research and Development
U.S. Envirpnmental Protection Agency
Cincinnati, OH 45268
Printed on Recycled Paper
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NOTICE
This guide has been subjected to U.S. Environmental Protection Agency
peer and administrative review 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 trade names or
commercial products constitute endorsement or recommendation for use.
This document is intended as advisory guidance only to the metal casting
and heat treating industries in developing approaches for pollution prevention.
Compliance with environmental and occupational safety and health laws is the
responsibility of each individual business and is not the focus of this
document. ;
Worksheets are provided for conducting waste minimization assessments
of the metal casting and heat treating industries. Users are encouraged to
duplicate portions of this publication as needed to implement a waste
minimization program. '
11
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FOREWORD
This guide identifies and analyzes waste minimization techniques and
technologies appropriate for the metal casting and heat treating industries.
The guide focuses primarily on source reduction and secondarily on recycling
methods.
The majority of waste generated by the metal casting or foundry industry
is from melting operations, metal pouring, and disposal of spent molding
materials. Generation of waste is directly related to the type of material
melted and depends on the types of molds and cores used, as well as the tech-
nology employed. The majority of waste generated by the heat treating indus-
try is from spent baths (e.g., cyanide solutions), spent quenchants, wastewater
from cleaning parts, spent abrasive media, refractory material, and masking
processes.
in
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ACKNOWLEDGMENTS
This guide is based in part on waste minimization assessments conducted
by Jacobs Engineering Group, Inc., Pasadena, California, for the California
Department of Health Services (DHS). Contributors to these assessments
include Ben Fries and Eric Workman of the Alternative Technology Section
of DHS; the various individuals at the cooperating metal casting and heat
treating firms that participated in this study; and Michael Meltzer, Maria
Zdunkiewicz, Carl Fromm, and Michael Callahan of Jacobs Engineering.
Much of the information in this guide was provided originally to the
California Department of Health Services by Jacobs Engineering in Waste
Audit Study: Thermal Metal Working Industry, (December 1990). Battelle
Memorial Institute edited and expanded this version of the waste minimization
assessment guide under contract to EPA (USEPA Contract 68-CO-0003).
Battelle personnel contributing to this guide include Bob Olfenbuttel, work
assignment manager; Tom Bigelow and Leslie Hughes, task leaders; S. L.
Semiatin and R. D. Tenaglia, technical engineers; and Bea Weaver, production
editor. \
i
Teresa Harten of the U.S. Environmental Protection Agency, Office of
Research and Development, Risk Reduction Engineering Laboratory, was the
project officer responsible for the preparation and review of this guide. Other
contributors and reviewers include Red Clark, Ross Fuller, Wendy B^rrott,
James White, and Dieter S. Leidel of the Water Quality and Waste Disposal
Committee of the American Foundrymen's Society, Inc.; Thomas Chase, Pres-
ident, Electric Heat Treating Co.; and Ben Fries, California Department of
Health Services.
IV
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CONTENTS
Section
Notice
Foreword
Acknowledgments
1. Introduction
Overview of Waste Minimization
Waste Minimization Opportunity Assessment
References
2. Metal Casting and Heat Treating Industry Profiles
Industry Description
Metal Casting Industry
Heat Treating Industry
References
3. Waste Minimization Options for Metal Casting, and Heat Treating Facilities
Introduction
Metal Casting Industry
Heat Treating Industry
Economics
References
4. Guidelines for Using the Waste Minimization Assessment Worksheets ....
APPENDIX A:
Metal Casting and Heat Treating Facility Assessments:
Case Studies of Plants
APPENDIX B:
Where to Get Help: Further Information on Pollution Prevention
Page
ii
iii
iv
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1
1
4
5
5
12
17
18
18
18
25
30
31
33
48
61
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SECTION!
INTRODUCTION
This guide is designed to provide the metal casting
and heat treating industry with waste minimization
options. It also provides worksheets for carrying out
waste minimization assessments for metal casting and
heat treating plants. It is envisioned that this guide
will be used by metal casting and heat treating com-
panies, particularly their plant operators and environ-.
mental engineers. Others who may find this docu-
ment useful are regulatory agency representatives,
industry suppliers, and consultants.
lii the following sections of this manual you will
find:
A profile of the metal casting and heat treating
industry and the processes used in it (Section 2)
Waste minimization options for the industry
(Section 3)
Waste minimization assessment guidelines and
worksheets (Section 4)
Appendices, containing
Case studies of waste generation and waste
minimization practices in the industry
Where to get help: additional sources of
information.
The worksheets and the list of waste minimization
options were developed from assessments of firms in
Southern California commissioned by the California
Department of Health Services (DHS 1990). Opera-
tions, manufacturing processes, and waste generation
and management practices were surveyed, and existing
and potential waste minimization options were
characterized.
Overview of Waste Minimization
Waste minimization is a policy specifically man-
dated by the U.S. Congress in the 1984 Hazardous
and Solid Wastes Amendments to the Resource Con-
servation and Recovery Act (RCRA). As the federal
agency responsible for writing regulations under
RCRA, the U.S. Environmental Protection Agency
(EPA) has an interest in ensuring that new methods
and approaches are developed for minimizing hazard-
ous waste and that such information is made available
to the industries concerned. This guide is one of the
approaches EPA is using to provide industry-specific
information about hazardous waste minimization. The
options and procedures outlined can also be used in
efforts to minimize other wastes generated in a
business, including air emissions, wastewater
discharges, and solid waste.
In the working definition used by EPA, waste min-
imization consists of source reduction and recycling.
Of the two approaches, source reduction is preferable
to recycling. While a few states consider treatment of
waste an approach to waste minimization, EPA does
not, and thus treatment is not addressed in this guide.
Waste Minimization
Opportunity Assessment
EPA has developed a general manual for waste
minimization in industry. The Waste Minimization
Opportunity Assessment Manual (USEPA 1988) tells
how to conduct a waste minimization assessment and
develop options for reducing hazardous waste genera-
tion at a facility. It explains the management strate-
gies needed to incorporate waste minimization into
company policies and structure, how to establish a
company-wide waste minimization program, conduct
assessments, implement options, and make the pro-
gram an ongoing one.
In 1992, EPA published the Facility Pollution
Prevention Guide (USEPA 1992) as a successor to the
Waste Minimization Opportunity Assessment Manual.
While the Waste Minimization Opportunity Assessment
Manual concentrated primarily on the waste types
covered in the Resource Conservation and Recovery
Act (RCRA), the Facility Pollution Prevention Guide
deals with "multimedia'' pollution prevention. It is
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intended to help small- to medium-sized production
facilities develop broad-based, multimedia pollution
prevention programs. Methods of evaluating,
adjusting, and maintaining the program are described.
Later chapters deal with cost analysis for pollution
prevention projects and with the roles of product
design and energy conservation in pollution
prevention. Appendices consist of materials that will
support the pollution prevention effort: assessment
worksheets, sources of additional information,
examples of evaluative methods, and a glossary.
A Waste Minimization Opportunity Assessment
(WMOA), sometimes called a waste minimization
audit, is a systematic procedure for identifying ways
to reduce or eliminate waste. The four phases of a
waste minimization opportunity assessment are
planning and organization, assessment, feasibility
analysis, and implementation. The steps involved in
conducting a waste minimization assessment are
outlined in Figure 1 and presented in more detail
below. Briefly, the assessment consists of a careful
review of a plant's operations and waste streams and
the selection of specific areas to assess. After a par-
ticular waste stream or area is established as the
WMOA focus, a number of options with the potential
to minimize waste are developed and screened. The
technical and economic feasibility of the selected
options are then evaluated. Finally, the most promis-
ing options are selected for implementation. The
following sections describe these steps in more detail.
PLANNING AND ORGANIZATION PHASE
Essential elements of planning and organization for
a waste minimization program are: getting manage-
ment commitment for the program, setting waste mini-
mization goals, and organizing an assessment program
task force.
ASSESSMENT PHASE
'The assessment phase involves a number of steps:
« Collect process and facility data
» Prioritize and select assessment targets
Select assessment team
Review data and inspect site
Generate options
» Screen and select options for feasibility study.
Collect Process and Site Data
The waste streams at a facility should be identified
and characterized. Information about waste streams
may be available on hazardous waste manifests,
National Pollutant Discharge Elimination System
(NPDES) reports, Toxic Release Inventory reports,
routine sampling programs, and other sources.
Developing a basic understanding of the processes
that generate waste at a facility is essential to the
WMOA process. Flow diagrams should be prepared
to identify the quantity, types, and rat<;s of waste gen-
erating processes. Also, preparing material balances
for the different processes can be useful in tracking
various process components and identifying losses or
emissions that may have been unaccounted for
previously.
Prioritize and Select Assessment Targets
Ideally, all waste streams in a facility should be
evaluated for potential waste minimization opportuni-
ties. If resources are limited, however, the plant man-
ager may need to concentrate waste minimization
efforts in a specific area Such considerations as
quantity of waste, hazardous properu'iss of the waste,
regulations, safety of employees, economics, and other
characteristics need to be evaluated in selecting target
streams or operations.
Select Assessment Team
The team should include people wilh direct respon-
sibility for and knowledge of the particular waste
stream or area of the facility being assessed. Equip-
ment operators and people involved in routine waste
management should not be ignored.
Review Data and Inspect Site
The assessment team evaluates process data in
advance of the inspection. The inspection should fol-
low the target process from the point where raw mate-
rials enter to the point where products and wastes
leave. The team should identify the suspected sources
of waste. This may include the production processes;
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The Recognized Need to Minimize Waste
PLANNING AND ORGANIZATION
Get management commitment
Set overall assessment program goals
' Organize assessment program task force
Assessment Organization &
Commitment to Proceed
ASSESSMENT
Collect process and facility data
Prioritize and select assessment targets
Select people for assessment teams
Review data and inspect site
Generate options
Screen and select options for further study
Select New Assessment
Targets and Reevaluate
Previous Options
Assessment Report of
Selected Options
FEASIBILITY ANALYSIS
Technical evaluation
Economic evaluation
Select options for implementation
Final Report, Including
Recommended Options
t
IMPLEMENTATION
Justify projects and obtain funding
p Installation (equipment)
Implementation (procedure)
1 Evaluate performance
Repeat the
Process
Successfully Implemented
Waste Minimization Projects
Figure 1. The Waste Minimization Assessment Procedure
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maintenance operations; and storage areas for raw
materials, finished products, and work in progress.
The inspection may result in the formation of prelimi-
nary conclusions about waste minimization opportuni-
ties. Full confirmation of these conclusions may
require additional data collection, analysis, and/or site
visits. |
Generate Options
The objective of this step is to generate a compre-
hensive set of waste minimization options for further
consideration. Since technical and economic concerns
will be considered in the later feasibility step, no
options are ruled out at this time. Information from
the site inspection, as well as from trade associations,
government agencies, technical and trade reports,
equipment vendors, consultants, plant engineers, and
operators may serve as sources of ideas for waste
minimization options.
Both source reduction and recycling options should
be considered. Source reduction may be accom-
plished through good operating practices, technology
changes, input material changes, and product changes.
Recycling includes use and reuse of water, solvents,
and other recyclable materials, where appropriate.
Screen and Select Options for Further Study
This screening process is intended to select the
most promising options for a full technical and eco-
nomic feasibility study. Through either an informal
review or a quantitative decision-making process,
options that appear marginal, impractical, or inferior
are eliminated from further consideration. ;
FEASIBILITY ANALYSIS PHASE
An option must be shown to be technically and eco-
nomically feasible in order to merit serious consid-
eration for adoption at a facility. A technical evalua-
tion determines whether a proposed option will work
in a specific application. Both process and equipment
changes need to be assessed for their overall effects
on waste quantity and product quality.
An economic evaluation is carried out using stan-
dard measures of profitability, such as payback period,
return on investment, and net present value. As in
any project, the cost elements of a waste minimization
project can be broken down into capital costs and
operating costs. Savings and changes! in revenue and
waste disposal costs also need to be considered, as do
present and future cost avoidances. In cases of
increasingly stringent government: requirements,
actions that increase the cost of production may be
necessary.
IMPLEMENTATION PHASE
An option that passes both technical and economic
feasibility reviews should be implemented. The proj-
ect can be turned over to the appropriate group for
execution while the WMOA team, with management
support, continues the process of tracking wastes and
identifying other Opportunities for waste minimization.
Periodic reassessments may be conducted to see if the
anticipated waste reductions were achieved. Data can
be tracked and reported for each implemented idea in
terms such as pounds of waste per production unit.
Either initial investigations of waste minimization
opportunities or the reassessments can be conducted
using the worksheets in this manual.
References
DHS. 1990. Waste Audit Study: Thermal Metal
Working Industry. Prepared by Jacobs Engineering
Group for Alternative Technology Section, Toxic
Substances Control Division, California Department
of Health Services.
USEPA. 1992. Facility Pollution Prevention Guide.
U.S. Environmental Protection Agency, Office of
Research and Development, Washington, D.C.,
EPA/600/R-92/088.
USEPA. 1988. Waste Minimization Opportunity As-
sessment Manual. U.S. Environmental Protection
Agency, Hazardous Waste Engineering Research
Laboratory, Cincinnati, EPA/625/7-88/003.
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SECTION 2
METAL CASTING AND HEAT TREATING INDUSTRY PROFILES
Industry Description
The Standard Industrial Classification (SIC) system
categorizes the metal casting and heat treating indus-
tries as foundries, casting (SIC 332X, 336X), and
metal heat treating (SIC 3398).
This document treats the metal casting and heat
treating industries as distinct from other thermally
intensive metal industries such as SIC 3312 (steel
works, blast furnaces, coke ovens, and rolling mills),
SIC 333X (primary/secondary smelting or refining of
nonferrous metals), SIC 335X (rolling, drawing, extru-
sion), and SIC 346X (forging and stamping).
Metal Casting Industry
Metal casting foundries range in size from small
job shops to large manufacturing plants that turn out
thousands of tons of castings each day. Generation of
waste is directly related to the type of material melted
(cast iron, steel, brass/bronze, or aluminum) and
depends on the type of molds and cores used, as well
as the technology employed. Wastes from sand cast-
ing operations are inherently greater than those from
permanent mold or die casting foundry operations.
Therefore, this guide focuses on sand foundries.
Table 1 lists the waste generated as a result of metal
casting processes.
PROCESS DESCRIPTION
The sand casting process (Figure 2) begins with
patternmaking. A pattern is a specially made model
of a component to be produced. Sand is placed
around the pattern to make a mold. Molds are usually
produced in two halves so that the pattern can be
easily removed. When the two halves are reassem-
bled, a cavity remains inside the mold in the shape of
the pattern.
Cores are made of sand and a binder and must be
strong enough to be inserted into a mold. Cores
shape the interior surfaces of a casting that cannot be
Table 1. Waste Generating Processes!
Metal Casting
Process
Waste
Molding and Coremaking Spent system sand
Sweepings, core butts
Dust and sludge
Melting
Casting
Cleaning
Dust and fumes
Slag
Investment casting
Shells and waxes
Cleaning room waste
shaped by the mold cavity surface. The patternmaker
supplies core boxes which are filled with specially
bonded sand for producing precisely dimensioned
cores. Cores are placed in the mold, and the mold is
closed. Molten metal is then poured into the mold
cavity, where it is allowed to solidify within the space
defined by the sand mold and cores.
Molding and Core Making
The molds used in sand casting consist of a panic-
ulate refractory material (sand) that is bonded together
to hold its shape during pouring. The most common
type of molding process is green sand molding.
Green sand is typically composed of sand, clay, car-
bonaceous material, and water. Sand constitutes 85 to
95 percent of the green sand mixture. Often the sand
is silica, but olivine and zircon are also used. Ap-
proximately 4 to 10 percent of the mixture is clay.
The clay acts as a binder, providing strength and plas-
ticity. Carbonaceous materials may make up 2 to
10 percent of the green sand mixture. Carbonaceous
materials are added to the mold to provide a reducing
atmosphere and a gas film during pouring that protects
against oxidation of the metal. Some of the more
common carbonaceous materials include sea coal (a
finely ground bituminous coal), and proprietary petro-
leum products. Other carbonaceous materials such as
cereal (ground corn starch) and cellulose (wood flour)
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Pattern-
making
I
Coremaking
^-
Molding
I
Mold
Assembly
Melting
1
Pouring
1
Cooling
1
Shakeout
i
Riser Cutoff
&Gate
Removal
Initial Heat
Treatment
(Optional)
Cleaning &
Finishing
Final Heat
Treatment
(Optional)
Inspection &
Shipping
Figure 2. Simplified Flow Diagram of the Basic Operations
for Producing a Steel Casting
may be added to control sand expansion defects.
Water activates the clay binder and is usually added in
small percentages (2 to 5 percent).
Core sands composed of mixtures of sand, with
small percentages of binder, are used to produce inter-
nal cavities within a casting. Cores must be strong,
hard, and collapsible. Often the cores must be
removed within a casting through a small orifice arid,
therefore, the sand must collapse after the casting
solidifies.
Core sand is typically silica. Olivine and zircon
have also been used when specifications require core
sands with higher fusion points or densities. Binder
materials to hold the individual grains of sand together
vary considerably in composition and binding proper-
ties. Oil binders and synthetic binders are common.
Oil binders are combinations of vegetable or animal
oils and petrochemicals. Typical synthetic resin
binders.include phenolics, phenolfonnaldehyde, urea-
formaldehyde, urea-formaldehyde/ftirfuryl alcohol,
phenolic-isocyanate, and alkyd isocyaiiate.
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Chemical resin binders are frequently used for
foundry cores and less extensively for foundry molds.
Chemical binders provide increased productivity,
improved dimensional control, and better casting sur-
face quality. A wide variety of binders are available,
including:
Furan acid catalyzed no-bake binders. Furfuryl
alcohol is the basic raw material. The binders
can be modified with urea, formaldehyde, and
phenol. Phosphoric or sulfonic acids are used
as catalysts. The amount of resin ranges
between 0.9 to 2.0 wt% based on sand weight.
Acid catalyst levels vary between 20 to 50 per-
cent based on the weight of binder.
Phenolic acid catalyzed no-bake binders. These
are formed in a phenol/formaldehyde condensa-
tion reaction. Strong sulfonic acids are used as
catalysts.
Ester-cured alkaline phenolic no-bake binders.
These are formed with a two-part binder system
consisting of a water-soluble alkaline phenolic
resin and liquid ester co-reactants. Typically
1.5 to 2.0 percent binder based on sand weight
and 20 to 25 percent co-reactant based on the
resin are used to coat washed and dried silica
sand in core and molding operations.
Silicate/ester-catalyzed no-bake binders. So-
dium silicate binder and a liquid organic ester
(glycerol diacetate and triacetate or ethylene gly-
col diacetate) that functions as a hardening
agent are used. They may also be catalyzed
with CO2.
Oil urethane no-bake resins. These resins con-
sist of an alkyd oil type resin, a liquid amine/
metallic catalyst, and a polymeric methyl
di-isocyanate.
Phenolic urethane no-bake (PUN) binder.
Polyol-isocyanate system (mainly for aluminum,
magnesium, and other light-alloy foundries).
The nonferrous binders are similar to a PUN
system consisting of Part I (a phenol formalde-
hyde resin dissolved in a special blend of sol-
vents), Part II (a polymeric MDI-type isocyanate
in solvents), and Part III (an amine catalyst).
Alumina-phosphate no-bake binder. This binder
consists of an acidic, water soluble alumina-
phosphate liquid binder and a free-flowing pow-
dered metal oxide hardener.
Novolac shell-molding binders. Novolac resins
.of phenol-formaldehyde and lubricant (calcium
stearate in the quantity of 4 to 6 percent of resin
weight) are used as a cross-linking agent.
Hot box binders. The resins are classified as
furan or phenolic types. The furan types con-
tain furfuryl alcohol, the phenolic types are
based on phenol, and the furan-modified has
both. Both chloride and nitrate catalysts are
used. The binders contain urea and
formaldehyde.
Warm box binders. These consist of a furfuryl
alcohol resin that is formulated for a nitrogen
content less than 2.5 percent. Copper salts of
aromatic sulfonic acids in an aqueous methanol
solution are used as catalyst.
Precision foundries often use the investment casting
(or the lost-wax) process to make molds. In this pro-
cess molds are made by building up a shell comprised
of alternating layers of refractory slurries and stuccos,
such as fused silica, around a wax pattern. The
ceramic shells are fired to remove the wax pattern and
to preheat the shells for pouring.
Another sand molding process that is finding com-
mercial acceptance uses a polystyrene foam pattern
imbedded in loose unbonded traditional sand. The
foam pattern left in the sand mold is decomposed by
molten metal, hence the process is called "evaporative
pattern casting" or the "lost foam process."
Melting
The metal casting process begins with melting
metal to pour into foundry molds. Cupola, electric
arc, induction, hearth (reverberatory), and crucible
furnaces are all used to melt metal.
The cupola furnace (patented in 1794) is the oldest
type of furnace used in the metal casting industry and
is still used for producing cast iron. It is a fixed bed
cylindrical shaft furnace, in which alternate layers of
metal scrap and ferroalloys, together with foundry
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coke and limestone or dolomite, are charged at the
top. The metal is melted by direct contact with a
counter-current flow of hot gases from the coke com-
bustion. Molten metal collects in the well, where it is
discharged by intermittent tapping or by continuous
flow. Conventional cupola furnaces are lined with
refractory to protect the shell against abrasion, heat,
and oxidation. Lining thickness ranges from 4.5 to
12 inches. The most commonly used lining is fireclay
brick, or block. As the heat progresses, the refractory
lining in the melting zone is progressively fluxed
away by the high temperature and oxidizing atmo-
sphere and becomes part of the furnace slag.
A cupola furnace is usually equipped with an emis-
sion control system. The two most common types of
emission collection are the high-energy wet scrubber
and the dry baghouse. High-quality foundry grade
coke is used as a fuel source. The amount of coke in
the charge usually falls within a range of 8 to 16 per-
cent of the metal charge. Coke burning is intensified
by blowing oxygen enriched air through nozzles.
Electric arc furnaces are used primarily by large
steel foundries and steel mills. Heat is supplied by an
electrical arc established from three carbon or graphite
electrodes. The furnace is lined with refractories that
deteriorate during the melting process, thereby genera-
ting slag. Protective slag layers are formed in the fur-
nace by intentional addition of silica and lime. Fluxes
such as calcium fluoride may be added to make the
slag more fluid and easier to remove from the melt.
The slag protects the molten metal from the air and
extracts certain impurities. The slag removed from
the melt may be hazardous depending on the alloys
being melted.
Metal scrap, shop returns (such as risers, gates, and
casting scrap), a carbon raiser (or carbon rich scrap),
and lime or limestone are added to the furnace charge.
Fume and dust collection equipment controls air emis-
sions from the electric arc furnace.
Induction furnaces have gradually become the most
widely used furnaces for melting kon and, increas-
ingly, for nonferrous alloys. These furnaces have
excellent metallurgical control and are relatively pollu-
tion free. Induction furnaces are available in capaci-
ties from a few pounds to 75 tons. Coreless induction
furnaces are more typically in the range of 5 tons to
10 tons. In a coreless furnace, the refractory-lined
crucible is completely surrounded by a water-cooled
copper coil. In channel furnaces, the coil surrounds
an inductor. Some large channel units have a capacity
of over 200 tons. Channel induction furnaces are
commonly used as holding furnaces.
Induction furnaces are alternating current electric
furnaces. The primary conductor is a coil, which gen-
erates a secondary current by electromagnetic induc-
tion. Silica (SiO2), which is classified as an acid;
alumina (A12O3), classified as neutral; and magnesia
(MgO), classified as a basic material, are typically
used as refractories. Silica is often used in kon melt-
ing because of its low cost and because it does not
readily react with the acid slag produced when melt-
ing high silicon cast kon.
Reverberatory (hearth) and crucible furnaces are
widely used for batch melting of nonferrous metals
such as aluminum, copper, zinc, and magnesium. In a
crucible furnace, the molten metal is contained in a
pot-shaped shell (crucible). Electric heaters or fuel-
fired burners outside the shell generate the heat that
passes through the shell to the molten metal. In many
metal-melting operations, slag or dross builds up at
the metal surface line, and heavy unmelted slush resi-
due collects on the bottom. Both of these residues
shorten crucible life and must be removed arid either
recycled or managed as waste.
Casting
Once the molten metal has been treated to achieve
the desked properties, it is transfered to the pouring
area in refractory-lined ladles. Slag is removed from
the bath surface and the metal is poured into molds.
When the poured metal has solidified and cooled, the
casting is shaken out of the mold, and the risers and
gates are removed. Fumes or smoke from the metal
pouring area are typically exhausted to a dust collec-
tion device such as a baghouse.
Cleaning
After cooling, risers and runners are removed from
the casting using handsaws, abrasive cut-off wheels,
or arc cut-off devices. Parting line flash is removed
with chipping hammers. Contouring of the cut-off
areas and parting line is done with grinders. Castings
may be weld-repaired to eliminate defects.
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After mechanical cleaning, the metal casting is
blast cleaned to remove casting sand, metal flash, or
oxide. In blast cleaning, abrasive particles, usually
steel shot or grit, are propelled at high velocity onto
the casting surface to remove surface contaminants.
For aluminum castings, the process provides a uni-
form cosmetic finish, hi addition to cleaning the
workpiece.
High-carbon steel shot is typically used to clean
ferrous castings; sometimes a shot and grit mixture is
used. In the past, chilled iron grit and malleable abra*
sives were used. Aluminum castings are sandblasted
typically using an abrasion-resistant sand or crushed
slag.
Cast components that require special surface char-
acteristics (such as resistance to deterioration or an
appealing appearance) may be coated. Chemical
cleaning and coating operations may be performed at
the foundry, but often are performed off site at firms
specializing in coating operations. The most impor-
tant prerequisite of any coating process is cleaning the
surface. The choice of cleaning process depends not
only on the types of soil to be removed, but also on
the characteristics of the masking to be applied; typ-
ical coating operations include electroplating, hard-
facing, hot dipping, thermal spraying, diffusion,
conversion, porcelain enameling, and organic or fused
dry-resin coating. The cleaning process must leave
the surface in a condition that is compatible with the
coating process. For example, if a casting is to be
treated with phosphate and then painted, all oil and
oxide scale must be removed because these inhibit
good phosphating. If castings are heat treated before
they are coated, the choice of heat treatment condi-
tions can influence the properties of the coating, par-
ticularly a metallic or conversion coating. In most
cases, castings should be heat treated in an atmo-
sphere that is not oxidizing.
Molten salt baths, pickling acids, alkaline solutions,
organic solvents, and emulsifiers are the basic materi-
als used in cleaning operations. Molten salt baths
may be used to clean complex interior passages in
castings. In one electrolytic, molten salt cleaning
process, the electrode potential is changed so that the
salt bath is alternately oxidizing and reducing. Scale
and graphite are easily removed with reducing and
oxidizing baths, respectively. Molten salt baths cl§an
faster than other nonmechanical methods, but castings
may crack if they are still hot when salt residues are
rinsed off with water.
Parts are usually pickled in an acid bath prior to
hot dip coating or electroplating. Overpickling should
be avoided because a graphite smudge can form on
the surface. Because cast iron contains silicon, a film
of silica also can form on the surface as a result of
heavy pickling. This film can be avoided by adding
hydrofluoric acid to the pickling bath.
Chemical cleaning differs from pickling in that
chemical cleaners attack only the surface contami-
nants, not the iron substrate. Many chemical cleaners
are proprietary formulations; but, in general, they are
alkaline solutions, organic solvents, or emulsifiers.
Alkaline cleaners must penetrate contaminants and wet
the surface to be effective. Organic solvents com-
monly used in the past (naphtha, benzene, methanol,
toluene, and carbon tetrachloride) have been largely
replaced by chlorinated solvents, such as those used
for vapor degreasing. Solvents effectively remove
lubricants, cutting oils, and coolants; but are ineffec-
tive against oxides or salts. Emulsifiers are solvents
combined with surfactants; they disperse contaminants
and solids by emulsification. Emulsion cleaners are
most effective against heavy oils, greases, sludges,
and solids entrained in hydrocarbon films. They are
relatively ineffective against adherent solids such as
oxide scale.
After wet cleaning, an alkaline rinse is used on
casting to prevent short-term rust. This can be fol-
lowed by treatment with mineral oils, solvents com-
bined with inhibitors and film formers, emulsions of
petroleum-base coatings and water, and waxes.
Coating
Castings are coated using plating solutions, molten
metal baths, alloys, powdered metals, volatilized metal
or metal salt, phosphate coatings, porcelain enamels,
and organic coatings.
-------
WASTE DESCRIPTION
Product castings manufactured by foundries gener-
ate the following wastes:
Spent system sand from molding and core male-
ing operations and used core sand not returned
to the system sand (sweepings, core butts)
Investment casting shells and waxes
Cleaning room waste
Dust collector and scrubber waste
Slag
Miscellaneous waste.
Spent Foundry Sand
Most foundries reuse some portion of their core
making and molding sand; in many cases most of the
sand is reused. Green sand is reused repeatedly.
Fines build up as sands are reused, and a certain
amount of system sand must be removed regularly to
maintain the desired sand properties. The removed
sand, combined with the sand lost to spills and shake-
out, becomes the waste sand. Figure 3 illustrates the
primary sources of waste sand.
Dust and sludge produced from molding sand are
often collected as part of an air pollution control sys-
tem located over the molding and shakeout operations.
Waste can also be in the form of large clumps that are
screened out of the molding sand recycle system or in
the form of sand that has been cleaned from the
castings.
Core sand binders either partially or completely
degrade when exposed to the heat of the molten metal
during the pouring operation. Once loose, sand that
has had its binder fully degraded is often mixed with
molding sand for recycling or is recycled back into
the core sand process. Core butts are partially
decomposed core sand removed during shakeout.
They contain only partially degraded binder. The core
butts can be crushed and recycled into the molding
sand process, or may be taken to a landfill along with
broken or offspec cores and core room sweepings.
Molding sand and core sand waste accounts for 66 to
88 percent of the total waste generated by ferrous
foundries.
Brass or bronze foundries may generate hazardous
waste sand contaminated with lead, copper, nickel,
and zinc, often in high total and extractable concentra-
tions. Some core-making processes use strongly
acidic or basic substances for scrubbing the offgases
from the core making process. In the free radical cure
process, acrylic-epoxy binders are cured using an
organic hydroperoxide and SO2 gas. A wet scrubbing
unit absorbs the SO2 gas. A 5 to 10 percent solution
of sodium hydroxide at a pH of 8 to 14 neutralizes the
SO2 and prevents the by-product (sodium sulfite) from
precipitating out of solution. Usually, pH controlled
sludges are discharged to the sewer system as nonhaz-
ardous waste. If not properly treated, the waste may
be classified as hazardous corrosive waste.
Investment Casting Waste
Investment casting shells can be used only once
and are disposed hi landfills as a nonhazardous waste
unless condensates from heavy metal alloy constitu-
ents are present hi the shells. Waxes that are removed
from the casting shells can be recycled back into wax
sprues and runners for further reuse or can be sent to
a wax recycling operation for recovery.
Cleaning Room Waste
Cleaning room waste that is ultimately disposed in
a landfill includes used grinding whirls, spent shot,
floor sweepings, and dust from the cleaning room dust
collectors. This waste may be hazardous if it contains
excessive levels of toxic heavy metals.
Dust Collector and Scrubber Waste
During the melting process, a small percentage of
each charge is converted to dust or fumes collected by
baghouses or wet scrubbers. In steel foundries, this
dust contains varying amounts of zinc, lead, nickel,
cadmium, and chromium. Carbon-steel dust tends to
be high in zinc and lead as a result of the use of gal-
vanized scrap, while stainless steel dust is high in
nickel and chromium. Dust associated with nonfer-
rous metal production may contain copper, aluminum,
lead, tin, and zinc. Steel dust may be encapsulated
and disposed of in a permitted landfill, while
10
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New Sand
& Binder
w
Raw Metal
Stock
Casting
Casting
Shotblasting,
Grinding
& Finishing
Finished
Casting
Product
Shakeout
Note 1
Mixing &
Mulling
Molding &
Casting
Separated
Metal
Screening
& Milling
Note 2
Waste Sand
(Core
I Waste .
Note 1 Removing the molding sand from the casting
Note 2 Breaking up large chunks and separating
metal pieces
Note 3 Accommodating the new sand and binder
Figure 3. Primary Sources of Waste Sand
nonferrous dust is often sent to arecycler for recovery melted refractories, sand, coke ash (if coke is used),
of metal.
Slag Waste
Slag is a fairly complex, relatively inert glassy
mass with a complex chemical structure. It is com-
posed of metal oxides from the melting process,
and other materials. Slag may be conditioned by
fluxes to facilitate removal from the furnace.
Hazardous slag may be produced in melting opera-
tions if the charge materials contain significant
amounts of toxic metal such as lead, cadmium, and
chromium.
11
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To reduce the sulfur content of iron, some foundr
ries use calcium carbide desulfurization in the produc-
tion of ductile iron. The calcium carbide desulfuriza-
tion slag generated by this process may be classified
as a reactive waste.
Miscellaneous Waste
Most foundries generate miscellaneous waste that
varies greatly in composition, but makes up only a
small percentage of the total waste. This waste
includes welding materials, waste oil from forklifts
and hydraulics, empty drums of binder, and scrubber
lime.
Heat Treating Industry
Heat treating refers to the heating and cooling
operations performed on metal workpieces to change
their mechanical properties, their metallurgical strub-
ture, or their residual stress state. Heat treating
includes stress-relief treating, normalizing, annealing,
austenitizing, hardening, quenching, tempering,
martempering, austempering, and cold treating.
Annealing, as an example, involves heating a metallic
material to, and holding it at, a suitable temperature,
followed by furnace cooling at an appropriate rate.
Steel castings may be annealed to facilitate cold work-
ing or machining, to improve mechanical or electrical
properties, or to promote dimensional stability. Gray
iron castings may be annealed to soften them or to
minimize or eliminate massive eutectic carbides, thus
improving their machinability.
PROCESS DESCRIPTION
Heating, quenching, descaling, cleaning, and mask-
ing operations generate most of the waste in the heiat
treating industry. Table 2 lists the waste generating
processes and waste characteristics.
Heat Treating Other Than Case Hardening
Heat treating is performed in conventional fur-
naces, salt baths, or fluidized-bed furnaces. The basic
conventional furnace consists of an insulated chamber
with an external reinforced steel shell, a heating sys-
tem for the chamber, and one or more access doors to
the heated chamber. Heating systems are direct fired
or indirect heated. With direct-fired furnace equip-
Table 2. Waste Generating Processes
Heat Treating
Process
Waste
Heat Treating
Case Hardening
Quenching
Descaling
Refractory material
Spent salt baths
Spent quenchants
Spent abrasive media
Cleaning and Masking Solvents, abrasives
Copper plating waste
ment, work being processed is directly exposed to the
products of combustion, generally referred to as flue
products. Gas- and oil-fired furnaces are the most
common types of heat treating equipment Indirect
heating is performed in electrically lieated furnaces
and radiant-tube-heated furnaces with gas-fired tubes,
oil-fiied tubes, or electrically heated tubes. The heat-
ing operations (e.g., stress-relief, normalizing, anneal-
ing, austenitizing, tempering, martempering, and
austempering) do not generate hazardous waste. Re-
fractory materials (furnace lining) are Ihe only wastes
generated, and they ate disposed of as nonhazardous
waste.
To obtain better thermal control and more rapid
heating rates, salt bath furnaces are commonly used.
Salt bath furnaces consist of pots of molten salt heated
by direct resistance methods (an electric current is
passed through the salt) or by indirect fossil fuel or
electric resistance methods (the pot is placed within a'
furnace-like enclosure).
In the fluidized-bed furnace, gas is passed up
through a bed of dry, finely divided particles, typically
aluminum oxide. The turbulent motion and rapid
circulation of the particles in the furnace provide heat-
transfer rates comparable to those of conventional salt-
bath equipment The parts to 1>e treated are
submerged in a bed of fine solid particles held in
suspension by an upward flow of gas. Heat input to a
fluidized bed can be achieved using:
Internal-resistance-heated beds: Ihe gas and par-
ticles are heated by suitably sheathed internal-
resistance heated elements
12
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External-resistance heated beds: a fluidized bed
contained in a heat-resisting pot is heated by
external resistance elements
Direct-resistance heated beds: an electrically
conducting material such as carbon powder or
silicon carbide is employed as the bed material
External-combustion heated beds: a fluidized
bedj contained in a heat-resisting pot, is heated
by external gas firing
Submerged-combustion fluidized beds: the
combustion products pass directly through the
mass to be heated
Internal-combustion gas-fired beds: an air/gas
mixture is used for fluidization and ignited in
the bed, generating heat by internal combustion.
Drag-out loss of the fluidized-bed particles that are
removed by agitating, bouncing, and gas blowing can
be minimized by water spraying. Recovered particles
can then be reused after being dried, sieved, and
returned to the bed.
Case Hardening
Case hardening processes supply an adequate quan-
tity of carbon or nitrogen for absorption and diffusion
into the steel. These processes are carried out in
either gas-phase furnaces or in salt-bath furnaces that
are similar to the furnaces used for other heat treating
processes. Case hardening performed in liquid media
is the major source of waste.
These baths are used in liquid carburizing, liquid
cyaniding (carbonitriding), and liquid nitriding pro-
cesses that are classified as steel case hardening pro-
cesses. Table 3 shows the operating composition of
liquid carburizing baths. Low-temperature cyanide-
type carburizing baths (light case baths) usually are
operated in the temperature range of 845 to 900C
(1550 to 1650F), although for certain effects this
operating range sometimes is extended to 790 to 925C
(1450 to 1700F). High-temperature cyanide-type
carburizing baths (deep case baths) usually are oper-
ated in the temperature range of 900 to 955C (1650 to
1750F). Liquid cyaniding (carbonitriding) baths typi-
cally are operated at temperatures of 815 to 850C
(1500 to 1560F). The composition of both low-
temperature and high-temperature baths is provided to
satisfy individual requirements for carburizing activity
(carbon potential) within the limitations of manual
drag-out and replenishment.
Table 4 shows the compositions and properties of
sodium cyanide mixtures used in liquid cyaniding pro-
cesses that produce a file-hard, wear-resistant surface
on ferrous parts. A sodium cyanide mixture such as
grade 30 in Table 4, is generally used for cyaniding
on a production basis. This mixture is preferable to
any of the other compositions given in Table 4. The
inert salts of sodium chloride and sodium carbonate
are added to cyanide to provide fluidity and to control
the melting points of all mixtures.
Liquid nitriding is performed in a molten salt bath
composed of a typical mixture of sodium and potas-
sium salts. The sodium salts, which comprise 60 to
70 percent (by weight) of the total mixture, consist of
96.5 percent NaCN, 2.5 percent Na2CO3, and 0.5 per-
cent NaCNO. The potassium salts, 30 to 40 percent
(by weight) of the mixture, consist of 96 percent
KCN, 0.6 percent K2CO3, 0.75 percent KCNO, and
0.5 percent KC1. The cyanate content in all liquid
nitriding baths is responsible for the nitriding action,
and the ratio of cyanide to cyanate is critical.
Cyanide-containing baths used in liquid carburiz-
ing, liquid cyaniding, and liquid nitriding processes
undergo an aging process that generates undesirable
products of oxidation. Aging decreases the cyanide
content of the bath and increases the cyanate and
carbonate content. In a low-temperature cyanide-type
bath, several reactions occur simultaneously, depend-
ing on bath composition, to produce the following
various end products and intermediates: carbon (C),
alkali carbonate (Na2CO3 or K2CO3), nitrogen (N2 or
2N), carbon monoxide (CO), carbon dioxide (CO2),
cyanamide (Na2CN2 or BaQSy, and cyanate
(NaNCO). Two of the major reactions believed to
occur in the operating bath are the "cyanamide shift"
and the formation of cyanate:
2 NaCN <-> Na2CN2 + C
and either
2 NaCN + O2 -> NaNCO
or
NaCN + CO2 <-> NaNCO + CO
(1)
(2)
(3)
13
*
-------
Table 3. Operating Composition of Liquid Carburizing Baths
Composition of Bath, %
Constituent
Light Case,
Low Temperature
845 to 900°C (1550
to 1650°F)
Deep Case,
High Temperature
900to955°C(1650
to 1750°F)
Sodium cyanide
Barium chloride
Salts of other alkaline earth metals^
Potassium chloride
Sodium chloride
Sodium carbonate j
Accelerators other than those involving compounds of alkaline
earth metals(c)
Sodium cyanate
Density of molten salt
10 to 23
Oto 10
Oto25
20 to 40
30 max
Oto 5
1.0 max
1760kg/m3at900°C
6 to 16
30 to 55(a)
b to 10
0 to 20
Oto 20
30 max
Oto 2
0.5 max
2000 kg/m3 at 925
°C
(110 lb/ftd at 1650°F) (125 Ib/ff at 1700°F)
(a) Proprietary barium chloride-free deep-case baths are available.
(b) Calcium and strontium chlorides have been employed. Calcium chloride is more effective, but its'hygro-
scopic nature has limited its use.
(c) Among these accelerators are manganese dioxide, boron oxide, sodium fluoride, and sodium
pyrophosphate.
Table 4. Compositions and Properties of Sodium
Cyanide Mixtures for Cyaniding Baths
i
Grade
oonsmuent or
Property
Composition, %
Sodium cyanide
Sodium carbonate
Sodium chloride
Melting point, °C (°F)
Specific gravity
At 25°C (75°F)
At 860°C (1580°F)
96-98(a)
97
2.3
Trace
560
(1040)
1.50
1.10
75
75
3.5
21.5
590
(1095)
1.60
1.25
45
45.3
37.0
17.7
570
(1060)
1.80
1.40
30
30.0
40.0
30.0
625
(1155)
2.09
1.54
(a) Appearance: white crystalline solid. This grade also con-
tains 0.5% sodium cyanate (NaNCO) and 0.2% sodium
hydroxide (NaOH); sodium sulfide (Na2S) content is nil.
(b) Appearance: white granular mixture.
14
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Reactions that influence cyanate content proceed as
follows:
NaNCO + C -> NaCN + CO (4)
and either
4 NaNCO + 2 O2 -> 2 Na2CO3 + 2 CO + 4 N (5)
or
4 NaNCO + 4 CO2 -> 2 Na2CO3 + 6 CO + 4 N(6)
Reactions (5) and (6) deplete the activity of the
bath. Oxidation products in the bath media promote
unfavorable temperature gradients. In liquid nitriding,
the carbonate content is kept below 25 percent. Car-
bonate content is usually lowered by cooling the bath
to 850°F and allowing precipitated salt to settle to the
bottom of the salt pot. Another contaminant that
forms in the bath is a complex sodium ferrocyanide
Na4Fe(CN)6 that is removed by holding the bath at
649°C for about two hours to settle out the compound
in the form of sludge.
The salt baths in liquid carburizing, liquid nitriding,
and liquid cyaniding processes are considered hazard-
ous when spent. Typical baths. contain molten
sodium, potassium cyanide, and cyanate salts. In
liquid carburizing, nitriding, and cyaniding, the parts
are held at an appropriate high temperature in a mol-
ten salt. In carburizing processes, after the workpiece
is heat treated, it undergoes quenching for the purpose
of hardening. The quenching media becomes con-
taminated with the cyanide used in case hardening and
must be disposed of as hazardous waste. Spent
quenching oil or wastewater generated in the cyanide
heat treating cycle (liquid carburizing or cyaniding)
becomes hazardous waste because cyanide salts are
transferred to the oil bath or water bath as a result of
drag-out. Gas carburizing burns natural gas in a sealed
furnace and produces no hazardous waste. Gas nitrid-
ing employs ammonia gas to supply the nitrogen and
produces no solid hazardous waste.
Some case hardening processes require source
materials from which carbon and nitrogen can be gen-
erated. After the case hardening is completed, these
spent source materials may be hazardous waste.
Salts that contain barium compounds are sources of
hazardous waste. These salts are used in high temper-
ature applications such as hardening high-speed steel,
hot work steels, and other air hardening tool steels.
Quenching
Quenching is an integral part of liquid carburizing,
liquid cyaniding, and liquid nitriding. When the sur-
face of the steel absorbs a sufficient quantity of car-
bon or nitrogen from a hot molten salt bath, the part
is often quenched in mineral oil, paraffin-base oil, wa-
ter, or brine to develop a hard surface layer. Tool
steels that are liquid nitrided are not normally
quenched, but are cooled.
Quenching, a cooling operation in metal heat treat-
ing, can be accomplished by immersing a hot work-
piece in water, oil, polymer solution, or molten salt,
depending on the cooling rate required. In spray
quenching, streams of quenching liquid are applied to
local areas of a hot workpiece at pressures up to
120 psi. Fog quenching is the application of a fine
fog or mist of liquid droplets and the gas carrier as
cooling agents. Gas quenching cools faster than still
air and slower than oil. Water (3 to 5 percent caustic
solutions) and brine (5 to 10 percent sodium chloride)
are the quenchants most commonly used for carbon
steel. A water soluble polymer is sometimes used to
modify the quenching rate of a water quench. Oil
quenching is less drastic than water quenching and
produces less distortion. Commonly used quenchants
are mineral oils fortified with nonsaponifiable addi-
tives that increase their quenching characteristics and
lengthen their useful lives. Parts should never be
transferred directly from a cyanide-containing
carburizing bath to a nitrate-nitrite quench bath. This
can result in a violent reaction and may cause an
explosion.
A complete quenching system consists of a work
tank or machines, facilities for handling the parts
quenched, quenching medium, equipment for agitation,
coolers, heaters, pumps and strainers or filters,
quenchant supply tank, equipment for ventilation and
for protection against hazards, and equipment for
automatic removal of scale from tanks. Quenching is
a significant source of waste in the heat treating
industry. The waste consists of spent quenching
media in the form of spent baths and wastewater
generated when quenched workpieces are washed to
15
-------
remove either salt or oil that remains after the quench-
ing process. ' ,
Descaling
The intense heat of air or atmosphere in furnaces
may cause an oxide scale to form on the surface of
workpieces. Before further processing can take place,
this scale must be removed. Descaling can be accom-
plished by abrasive cleaning (sandblasting) or by pick-
ling. In pickling, the workplace is immersed in a hot
acid bath (usually sulfuric, nitric, or hydrochloric acid)
to clean the surface of all impurities. The acid dis-
solves the metal oxide and ferric oxide rust and scale.
The workpiece is then rinsed in water to remove the
acid and, in some cases, is bathed in oil or another
special coating.
Parts Cleaning and Surface Masking
Supportive operations in heat treating (such as parts
cleaning or surface masking) generate hazardous
waste. Masking by plating prevents carburizing or
nitriding of a metal workpiece or selected parts of a
workpiece during the heating cycle. Plated deposits of
bronze or copper are the most common coatings.
Nickel (including electroless nickel), chrome, and sil-
ver are effective also, but their higher cost restricts
their use to special applications. When the application
does not permit the retention of any protective plate
on die finished part after heat treating, selection of the
coating is important from the standpoint of subsequent
stripping. Copper and silver are the easiest to strip;
bronze is more difficult Nickel is very difficult to
remove without detrimentally affecting the part.
Therefore, copper plating is most widely used.
Cleaning parts is of great concern in plating and
case hardening processes. In liquid nitriding pro-
cesses, for example, all workpieces placed in the bath
should be thoroughly cleaned and free of surface
oxide, entrapped sand, oil and grease, and metal parti-
cles. Either acid pickling or abrasive cleaning is
recommended prior to nitriding. Most parts are suc-
cessfully nitrided immediately after vapor degreasing.
However, some machine finishing processes (such as
buffing, finish grinding, lapping, and burnishing) may
produce surfaces that retard nitriding and result in
uneven case depth and distortion even after cleaning.
There are two ways to condition the surfaces of
parts finished by such methods. One method consists
of vapor degreasing and abrasive cleaning with alumi-
num oxide grit immediately prior to liquid nitriding
(residual grit must be brushed off before parts are
loaded into the furnace). The second is to apply a
light phosphate coating.
WASTE DESCRIPTION
Spent cyanide baths, spent quenchaiits, wastewater
generated in parts cleaning operations, spent abrasive
media, refractory material, and plating generate the
most waste in the heat treating industry. The follow-
ing sections characterize waste from case hardening
baths and pots, quenchant baths, and parts cleaning
and masking operations.
Case Hardening Baths and Salt Pots
A significant amount of waste is generated in heat
treating operations where cyanide-confetining baths are
used. In normal bath maintenance routines, sludge
collected at the bottom of the pot is removed on a
daily basis. It is usually spooned from the bottom
with a perforated ladle. This sludge must be disposed
of and treated as waste. In liquid carburizing, sludge
is removed while the furnace is still at idling
temperature. The electrodes of internally heated fur-
naces are scraped clean. As the bath media is
depleted, bath pots corrode. To minimize corrosion of
the pot at the air-salt interface, salts are completely
changed every three or four months.
Quenching
Cyanide salts on the part contaminate the quench-
ing bath, rendering the bath a hazardous waste when
spent
Salt that adheres after the parts reach room tem-
perature must be washed off, usually in water.
Waste is generated in the following form:
Residue (salt sludge) from oil baths used for
quenching cyanided and liquid carburized and
nitrided parts
16
-------
Spent water and brine quenchants used for
liquid cyanided, liquid carburized, and liquid
nitrided parts
Quenching process drag-out waste from other
than case hardening processes.
Another source of waste is the quenchant media
washing operation. Drag-out in the form of oil is
removed from the part by hot water washing. Oil is
one of the most commonly used quenchants in the
heat treating industry, therefore the quantity of waste
oil that needs to be handled as a hazardous waste is
subtantial.
Parts Cleaning and Masking
Additional sources of hazardous waste in the heat
treating industry are parts cleaning and masking oper-
ations. Solvent cleaning, aqueous cleaning, and abra-
sive cleaning wastes are generated for disposal or tre-
atment.
The most popular masking operation is copper plat-
ing. The hazardous wastes generated in this process
are identical to metal finishing industry wastes. For
more information on the types of hazardous waste
generated in plating operations see USEPA Guides to
Pollution Prevention: The Fabricated Metal Industry
(Appendix B), USEPA Guides to Pollution Preven-
tion: the Metal Finishing Industry (Appendix B), and
DHS, Waste Audit Study (1989, 1990).
References
DHS. 1989. Waste Audit Study: Fabricated Metal
Products Industry, Prepared by Jacobs Engineering
Group for Alternative Technology Section, Toxic
Substances Control Division, California Department
of Health Services.
DHS. 1990. Waste Audit Study: Thermal Metal
Working Industry. Prepared by Jacobs Engineering
Group for Alternative Technology Section, Toxic
Substances Control Division, California Department
of Health Services.
USEPA. 1990. Guides to Pollution Prevention: The
Fabricated Metal Industry. EPA/625/7-90/006.
USEPA. 1992. Guides to Pollution Prevention:
Metal Finishing Industry.
The
17
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SECTION 3
WASTE MINIMIZATION OPTIONS FOR
METAL CASTING AND HEAT TREATING FACILITIES
Introduction
Management initiative, commitment, and involve-
ment are key elements in any waste reduction program
and include activities such as:
Employee awareness and participation
Improved operating procedures
Employee training
Improved scheduling of processes.
Employee training, awareness, and participation are
critically important and can be problematic aspects of
waste minimization programs. Employees are often
resistant to broadening their roles beyond the tradi-
tional concepts of quantity and quality of products
produced. Total commitment and support of manage-
ment and employees are needed for any waste minimi-
zation, program to succeed. This includes the evalua-
tion, implementation, and maintenance of techniques
and technologies to minimize waste. Companies are
advised to use mass balances around their facilities
and processes to help identify areas where waste is
occurring, perhaps unknowingly. The use of good
process control procedures to increase process effir
ciency is also recommended.
Companies should continually educate themselves
to keep abreast of improved waste-reducing, pollution-
preventing technology. Information sources to help
inform companies about such technology include trade
associations and journals, chemical and equipment
suppliers, equipment expositions, conferences, and
industry newsletters. By implementing better technol-
ogy, companies can often take advantage of the dual
benefits of reduced waste generation and a more cost
efficient operation.
Metal Casting Industry
The waste reduction options presented below for
the metal casting industry include source reduction
and recycling.
SOURCE REDUCTION OPTIONS FOR
BAGHOUSE DUST AND SCRUBBER WASTE
Alter Raw Materials
The predominant source of lead, zinc, and cad-
mium in ferrous foundry baghouse dust or scrubber
sludge is galvanized scrap metal used as a charge
material. To reduce the level of these contaminants,
then: source must be identified and charge material
containing lower concentrations of the contaminants
must be acquired. A charge modification program at
a large foundry can successfully reduce the lead and
cadmium levels in dust collector waste to below EP-
toxicity values (Stephens 1988). Foundries need to
work closely with steel scrap suppliers to develop
reliable sources of high-grade scrap.
Install Induction Furnaces
Induction furnaces offer advantages over electric
arc or cupola furnaces for some applications. An
induction furnace emits about 75 percent less dust and
fumes because of the absence of combustion gases or
excessive metal temperatures. When relatively clean
scrap material is used, the need for emission control
equipment may be minimized. Of course, production
operations and process economics must be considered
carefully when planning new or retrofit melting equip-
ment. For more information on induction furnaces,
refer to USEPA 1985 and Danielson 1973.
18
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RECYCLING OPTIONS FOR BAGHOUSE
DUST AND SCRUBBER WASTE
The dust in electric arc furnaces is typically col-
lected in baghouses. Electric arc furnace dust may
contain heavy metals such as lead, cadmium, and zinc,
which can make it a hazardous waste. The following
options focus on recycling heavy metals from steel
foundry electric arc furnace dust.
Recycle to the Original Process
Electric arc furnaces (EAFs) generate 1 to 2 per-
cent of their charge into dust or fumes (Chaubal
1982). If the zinc and lead levels of the metal dust are
relatively low, return of the dust to the furnace for
recovery of base metals (kon, chromium, or nickel) is
often feasible. This method may be employed with
dusts generated by the production of stainless or alloy
steels. However, this method is usually impractical
for handling dust associated with carbon steel produc-
tion because galvanized metal scrap is used. In the
production of carbon steels from galvanized scrap,
recovered dust tends to be high in zinc.
Many methods have been proposed for flue-dust
recycling, including direct zinc recovery (Morris
1985). Most recovery options require the zinc content
of the dust to be at least 15 percent, preferably
20 percent, for the operation to be economical. Zinc
content can be increased by returning the dust to the
furnace from which it is generated. If the dust is
injected into the furnace after the charge of scrap
metal is melted, temperatures are high enough for
most of the heavy metals to fume off. This results in
an increased zinc concentration in the dust collected
by the scrubbers, electrostatic precipitation systems, or
baghouses.
Recycle Outside the Original Process
Waste can be reused outside the original process by
reclaiming the zinc, lead, and cadmium concentrated
in emission control residuals. The feasibility of such
reclamation depends on the cost of dust treatment and
disposal, the concentration of metals within the resid-
ual, the cost of recovering the metals, and the market
price for the metals. While this approach is useful in
the nonferrous foundry industry (i.e., brass foundries),
its application within gray iron foundries is extremely
limited. Some foundries market furnace dust as input
to brick manufacturing and other consumer product
applications, but product liability limits this option.
Pyrometallurgical, rotary kiln, electrothermic shaft
furnace, and zinc oxide enrichment recovery methods
are described below. Promising processes for zinc
recovery are examined in Morris 1985.
Pyrometallurgical Methods. Pyrometallurgical
methods for metals recovery are based on the reduc-
tion and volatilization of zinc, lead, cadmium, and
other components of EAF dust. The chemistry of
these processes is described in Kellogg 1966. A
reducing environment favors zinc and cadmium oxide
vaporization and removal, while an oxidizing environ-
ment favors removal of lead by oxide vaporization.
Thus, lead is preferentially removed through roasting
in air, while the other metals are removed through
roasting under reducing conditions (Dressel 1974).
Rotary Kiln Technology. The rotary (or Waelz)
kiln can handle a variety of dusts, as well as other
materials containing zinc (Morris 1985). This process
can simultaneously reduce ferrous iron oxide to solid
kon and lead and zinc oxide to thek metallic forms,
using a reducing atmosphere such as carbon monoxide
and hydrogen (Krishnan, 1983). Rotary kilns have
been used worldwide on many types of zinc-
containing materials, thus thek operating conditions
and costs are well documented (Krishnan 1982). The
biggest disadvantage of the rotary kiln is that it must
be fairly large to be economically and thermally
efficient. Also, chlorine in the EAF dust must be
removed through washing or roasting before metallic
zinc can be produced.
Electrothermic Shaft Furnace. The electrothermic
shaft furnace can extract zinc from a feed containing
at least 40 percent of the metal. Typically, agglomer-
ated EAF dust is mixed with other feed to attain this
percentage (Bounds 1983 and Miyashita 1976). Zinc
is recovered hi its metallic form, from which a very
salable Prime Western Grade can be made.
Zinc Oxide Enrichment. To recycle dust by dkect
reduction of oxides, kon oxide is reduced to kon and
water using pure hydrogen at a temperature range of
1000 to 1100°C (AFS 1989). Reducing zinc oxide by
reacting it with hydrogen requkes recycling hydrogen
to the furnace in a second pass.
19
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The reduction of zinc oxide produces zinc vapors
and steam at 1000 to 1100°C that are removed from
the furnace and subjected to an oxidation step. The
zinc reacts with water to produce zinc oxide, and
hydrogen is recovered and recycled. The zinc oxide
produced is separated in a baghouse. The hydrogen
containing the steam is further treated for steam con-
densation, and then the hydrogen is ready for recy-
cling into the furnace.
In lab scale experiments using dust containing 35
to 40 percent iron, the sponge kon contained 58 per-
cent iron and the separated ZnO contained 56 percent
zinc. The cadmium and lead were below EP toxicity
criteria. The ZnO produced can be used as a crude
zinc oxide product for further upgrading. This
method of electric arc dust recycling having proved
technically feasible, a preliminary design was devel-
oped for a prototype system with a capacity of
2.5 tons of dust charged to the furnace in a single
batch. The ZnO recovery cost was estimated at $159
per ton of dust.
Recycle to Cement Manufacturer
Silica-based baghouse dust from sand systems and
cupola furnaces may be used as a raw material by
cement companies (Kelly 1989, AFS 1989). The dust
is sent into a primary crusher and then preblended
with other components and transferred to a kiln oper-
ation. It is envisioned that baghouse dusts may con-
stitute 5 to 10 percent of the raw material used by
cement manufacturers in the near future. The use of
higher levels may be limited by the adverse effects of
the baghouse dust on the setting characteristics of the
cement
SOURCE REDUCTION OPTIONS FOR
HAZARDOUS DESULFURIZING SLAG
In the production of ductile iron, it is often
necessary to add a desulfurizing agent in the melt to
produce the desired casting microstructure. One
desulfurization agent commonly used is solid calcium
carbide (CaCj). Calcium carbide is thought to decom-
pose to calcium and graphite. The calcium carbide
desulfurization slag is generally removed from the
molten kon in the ladle and placed into a hopper. For
adequate sulfur removal, calcium carbide must be
added in slight excess. Therefore, the slag contains
both CaS and CaC2. Since an excess of CaC^ is
employed to ensure removal of the sulfur, the result-
ing slag must be handled as a reactive waste. The
slag might also be hazardous due to high concentra-
tions of heavy metals.
Treatment of this material normally consists of
converting the carbide to acetylene and calcium
hydroxide by reacting with water (Stolzenburg 1985).
Problems with this method include handling a poten-
tially explosive waste material; generating a waste
stream that contains sulfides (due to calcium sulfide in
the slag) and many other toxic compounds; and liber-
ating arsine, phosphine, and other toxic materials in
the off gas.
Alter Feed Stock
One way to reduce the need for calcium carbide is
to reduce the amount of high sulfur scrap used as fur-
nace charge materials. While this method is effective,
the ability to obtain a steady supply of high-grade
scrap varies considerably, and the economics usually
favor a different solution (Stephens 1988).
Alter Desulfurization Agent '
To eliminate the use of calcium carbide, several
major foundries have investigated the use of alter-
native desulfurization agents (Stephens 1988). One
proprietary process employs calcium oxide, calcium
fluoride, and two other materials. Not only is the
quality of the kon satisfactory, but the overall process
is economically better than carbide desulfurization.
Alter Product Requirements
Quite often, the specifications for a product are
based not on the requkements of that product but on
what is achievable in practice. When total sulfur
removal is requked, it is not uncommon that 20 to
30 percent excess carbide is employed. The excess
carbide then ends up as slag and creates a disposal
problem. If the kon were desulfurized only to the
extent actually needed, much of this waste could be
reduced or eliminated (Stephens 1988).
Improve Process Control
In an attempt to reduce calcium carbide usage, and
hence waste production, improved process controls are
being developed that use different ways of introducing
20
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the material into the molten metal (Stephens 1988).
Very fine granules, coated granules, and solid rods of
calcium carbide have been investigated as ways of
controlling the reaction more closely.
RECYCLING OPTIONS FOR
HAZARDOUS DESULFURIZING SLAG
Recycle to Process
Because calcium carbide slag is often removed
from the metal by skimming, it is not uncommon to
find large amounts of iron mixed in with the slag.
Depending on the means of removal, this metal will
either be in the form of large blocks or small gran-
ules. To reduce metal losses, some foundries crush
the slag and remove pieces of metal by hand or with a
magnet for remelting.
Other foundries have investigated recharging the
entire mass to the remelting furnace (Stephens 1988).
Inside the furnace, calcium hydroxide forms in the
slag as the recycled calcium carbide either removes
additional sulfur or is directly oxidized. While this
method has been successful, much work still remains
to be done. For example, it is not known to what
extent the calcium sulfide stays with the slag or how
much sulfur is carried in the flue gas and the scrubber
system. Initial tests indicate that the sulfur does not
concentrate in the metal, so that product quality is not
affected.
Recycle to Other Process Lines
Slag from stainless steel melting operations (where
Ni, Mo, and Cr metals are used as alloy additions) is
hazardous as a result of high nickel and chromium
concentrations. Such slag can be recycled as a feed to
cupola furnaces (gray iron production line). The
cupola furnace slag scavenges trace metals from the
induction furnace slag. The resulting cupola slag may
be rendered a nonhazardous waste.
SOURCE REDUCTION OPTIONS
FOR SPENT CASTING SAND
In most foundries, casting sands are recycled
internally until they can no longer be used. At that
time, many of the sands, such as those from iron
foundries, are landfilled as nonhazardous waste. Cast-
ing sands used in the production of brass castings may
be contaminated with lead, zinc, and copper conden-
sates and must be disposed of as hazardous waste.
Waste Segregation
A California DHS study (DHS 1989) concluded
mat a substantial amount of sand contamination comes
from mixing shot blast dust with waste sand in brass
foundries. In nonferrous foundries, shot blast dust (a
hazardous waste stream) should be kept separate from
nonhazardous foundry sand waste streams.
The overall amount of sand being discarded can be
significantly reduced by implementing the following
waste segregation steps:
Replumbing the dust collector ducting on the
casting metal gate cutoff saws to collect metal
chips for easier recycling
Installing a new baghouse on the sand system to
separate the sand system dust from the furnace
dust
Installing a new screening system on the main
molding sand system surge hopper to continu-
ously clean metal from the sand system
Installing a magnetic separation system on the
shotblast system to allow the metal dust to be
recycled
Changing the core sand knockout procedure to
keep this sand from being mixed in with system
sand prior to disposal
Detoxifying sand that remains unusable as a
result of size reclassification after sand
reclamation.
RECYCLING OPTIONS
FOR SPENT CASTING SAND
Screen and Separate Metal from Sand
Most foundries screen used sand before reusing it.
Some employ several different screen types and
vibrating mechanisms to break down large masses of
sand mixed with metal chips. Coarse screens are used
to remove large chunks of metal and core butts. The
larger metal pieces collected in the screen are usually
21
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remelted in the furnace or sold to a secondary smelter;
Increasingly fine screens remove additional metal
particles and help classify the sand before it is
molded. Some foundries remelt these smaller metal
particles; other foundries sell this portion to metal
reclaimers. The metal recovered during the screening
process is often mixed with coarser sand components
or has sand adhering to it Therefore, remelting these
pieces in the furnace generates large amounts of slag,
especially when the smaller particles are remelted.
The Chicago Faucet Co., a red brass foundry,
reports (AFS 1989) that the material generated from
the sand screening system is recycled in a ball mill.
All the furnace skims, floor spills, slags, core butts,
and tramp metal from screening ace dumped into a
vibrator. The vibrator feeds a rotating ball mill that
pulverizes all materials into very small particles that
are discharged to a vibrating trough. This trough
feeds an elevator that discharges into a receiving hop-
per. Pulverized sand and slag pass through a vibrat-
ing screen and come out the bottom into a hopper.
The material to be recycled goes through an impactor
and back across the vibrating screen. More than
95 percent of the remaining clean metallics can be
returned to the furnace. The baghouse from the ball
mill contains approximately 14 percent copper metal-
lics, which is a waste stream.
Reclaim Metal and Sand
A process for reclaiming metal and sand in brass
foundries is shown in Figure 4 (AFS 1989). First the
sand is processed to physically remove as much of the
brass metal as possible. This material has relatively
high value, and constitutes from one-half to two-thirds
of the heavy metal in the sand. The physical separa-
tion processes include gravity, size, and magnetic
separation units (for any iron-based contaminants).
The second stage of the process removes the heavy
metals found in the fines and the coatings from the
sand. The chemical process consists of mineral acid
leaching, followed by metal recovery.
According to PMET (Pittsburgh Mineral Environ-
mental Technology), the chemical treatment step
decreases the EP or TCLP lead values 50 to 500 times
below the present regulatory thresholds. A bleed
stream in the chemical process generates spent acid
that must be disposed of. However, the end waste
stream is reported to be nonhazardous and may have
salable value.
Reclaim Sand by Dry Scrubbing/Attrition
This method is widely used, and a large variety of
equipment is available with capacities adaptable to
most binder systems and foundry operations. Dry
scrubbing may be divided into pneumatic, mechanical,
and combined thermal-calcining/thermall-dry scrubbing
systems.
In pneumatic scrubbing, grains of sand are agitated
in streams of air normally confined in vertical steel
tubes called cells. The grains of sand are propelled
upward and impact each other, thus removing some of
the binder. In some systems, grains are impacted
against a steel target. Banks of tubes may be used
depending on the capacity and degree of cleanliness
desired. Retention time can be regulated, and fines
are removed through dust coUectors. In. mechanical
scrubbing, available equipment offers foundries a
number of options. An impeller may be used to
accelerate the sand grains at a controlled velocity in a
horizontal or vertical plane against a metal plate. The
sand grains .impact each other and metal targets,
thereby removing some of the binder. The speed of
rotation has some control over impact energy. The
binder and fines are removed by exhaust systems, and
screen analysis is controlled by air gates or air wash
separators. Additional equipment optioos include:
A variety of drum types with internal baffles,
impactors, and disintegrators that reduce lumps
to grains and remove binder
Vibrating screens with a series; of decks for
reducing lumps to grains, with recirculating fea-
tures and removal of dust and fines
Shot-blast cleaning equipment that may be
incorporated into other specially designed units
to form a complete casting cleaning/sand recla-
mation unit
Vibro-energy systems that use synchronous and
diametric vibration. Frictional and compressive
forces separate binder from the sand grains.
22
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Reagents
J
Metal Product
Weight = 0.5-1.0%
Bleed
1
EP Toxicity
10-30ppmPb
Feed Sand
Weight = 100%
i
Physical
Separation
.
Chemical
Separation
1 1
EP Toxicity
< 0.1 0-30 ppmPb
Clean Sand
Weight = 98-99%
I
Metal Product
Weight = 0.5%
Figure 4. Simplified Process Flow Diagram for Sand Treatment
in Brass Foundries (from AFS, 1989)
Reclaim Sand with Thermal Systems
Most foundries recycle core and mold sands; how-
ever, these materials eventually lose their basic char-
acteristics, and the portions no longer suitable for use
are disposed of in a landfill. In the reclamation of
chemically or resin bonded sands, the system
employed must be able to break the bond between the
resin and sand and remove the fines that are gener-
ated. The systems most commonly employed are wet
washing and scrubbing for silicate-bonded sands, or
dry scrubbing/attrition and thermal (rotary reclama-
tion) systems for resin-bonded sands.
Reclamation of clay-bonded molding sand (green
sand) has been practiced on a limited basis in Japan
for the past 20 years and is currently being reevalu-
ated in the United States (ASM 1988). Wet reclama-
tion systems employed in the 1950s for handling clay
bonded sands are no longer used. Specific thermal
reclamation case studies are summarized in AFS 1989.
A typical system to reclaim chemically bonded sand
for reuse in coreroom and molding operations consists
of a lump reduction and metal removal system, a
particle classifier, a sand cooler, a dust collection sys-
tem, and a thermal scrubber (two-bed reactor).
Thermal Calcining/Thermal Dry Scrubbing. These
systems are useful for reclamation of organic and
clay-bonded systems. Sand grain surfaces are not
smooth; they have numerous crevices and indenta-
tions. The application of heat with sufficient oxygen
calcines the binders or burns off organic binders.
Separate mechanical attrition units may be required to
remove calcined inorganic binders. Heat offers a
simple method of reducing the encrusted grains of
molding sand to pure grains. Both horizontal and
vertical rotary kiln and fiuidized bed systems are
available.
Rotary Drum. This system has been used since the
1950s for reclaiming shell and chemically bonded
sands. The direct-fired rotary drum is a refractory-
lined steel drum that is mounted on casters. The feed
end is elevated to allow the sand to flow freely
through the unit. The burners can be at either end of
the unit with direct flame impingement on the cascad-
ing sand; flow can be either with the flow of solids or
counter to it.
In indirect-fired units, the drum is mounted on
casters in the horizontal position and is surrounded by
refractory insulation. Burners line the side of the
23
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drum, with the flames in direct contact with the metal
drum. The feed end is elevated to allow the sand to
flow freely through the unit, and in some cases flights
(paddles connected by chains) are welded to the inside
to assist material flow.
Multiple-Hearth Vertical Shaft Furnace. This fur-
nace consists of circular refractory hearths placed one
above the other and enclosed in a refractory-lined
steel shell. A vertical rotating shaft through the center
of the furnace is equipped with air-cooled alloy arms
containing rabble blades (plows) that stir the sand and
move it in a spiral path across each hearth.
Sand is repeatedly moved outward from the center
of a given hearth to the periphery, where it drops
through holes to the next hearth. This action gives
excellent contact between sand grains and the heated
gases. Material is fed into the top of the furnace. It
makes its way to the bottom in a zigzag fashion,
while the hot gases rise counter-currently, burning the
organic material and calcining clay, if one or both are
present Discharge of reclaimed sand can be directly
from the bottom hearth into a tube cooler, or other
cooling methods may be used. The units are best
suited to large tonnages (five tons or more).
New approaches and equipment designed for sand
reclamation units are continuing to evolve, and found-
ries must evaluate each system carefully with regard
to the suitability for a particular foundry operation.
Use Sand as a Construction Material
Nonhazardous foundry waste has been used in
municipal waste landfills as a supplement for daily
earth cover (Smith 1982). This practice has received
scrutiny recently because of concerns about mixing
industrial and municipal waste and resulting pollution
problems. An alternative is using selected foundry
wastes for both final cover and as a topsoil substitute
for foundry landfills. Another option is to use
foundry sand and other waste for construction fill
(Smith 1982).
I
The suitability of these options depends on the
physical and chemical nature of the waste; its intended
use; the amount of waste to be handled; local market
conditions for the waste; and federal, state, and local
regulations regarding its handling, storage, and dispo-
sal. In addition, some foundries have explored using
foundry sand in road beds or to manufacture asphalt
and cement, making certain that these options are not
considered "use in a manner constituting disposal."
The University of Wisconsin-Madison has per-
formed a substantial amount of research on the suit-
ability of using spent foundry sand as a substitute
cover and fill raw material (Engroff et al. 1989,
Costello et al. 1983, Stephens et al. 1986, Traeger
1987, and Wellander 1988). TCLP and AFS leaching
potential for inorganics and nonvolatile organics were
examined, as well as overall physical properties of the
samples for use as construction fill. The wastes
chosen were from three foundries and included spent
system sand and core butts. The binder systems used
at these foundries included clay/water, shell, phenolic
urethane, sodium silicate, oil, phenol-formaldehyde,
and urea-formaldehyde. This research showed that:
None of the samples leached would be defined
as hazardous by RCRA identification criteria.
The leaching tests showed generally low release
of all parameters tested, most at concentrations
below drinking water standards
On the average, only Fe, Mn, and TDS (total
dissolved solids) exceeded drinking water
standards
Low levels of TOC (total organic carbon), cya-
nides, and phenols in leachates suggest there
will be little or no problem with organics
« Natural soils leached for comparison released
comparable and sometimes higher levels of
substances
Foundry sand leaching characteristics varied
little over time and among different waste
streams within a given foundry
Physical properties of foundry sand are appro-
priate for use as road fill material.
Additional investigations on a wider range of the most
commonly used organic binder systems identified by
AFS confirmed that no leaching of volatile organics
occurred at concentrations above TCLP regulatory
levels.
24
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In light of these and other similar findings, a num-
ber of states are reexamining their existing solid waste
regulations to create special waste categories that will
allow nonhazardous materials such as spent foundry
sand to be reused beneficially for landfill construction,
daily cover, road fill, and construction fill.
Bituminous concrete, commonly called asphalt, is
another potential reuse market for foundry waste.
Asphalt consists of varying proportions of coarse and
fine aggregate and bitumen, a tar-like petroleum-based
bonding agent. AFS research (1991) has verified that
asphalt made using foundry sand as a partial aggregate
replacement will meet standard ASTM specifications.
Japanese research (Fujii and Imamura 1980, 1984) has
yielded similar findings. In Canada, the Ministry of
Transport for the Province of Ontario has been using
spent foundry sand in asphalt mixes for nearly
15 years with no deleterious effects, other than a
slightly altered surface appearance.
Portland cements are hydraulic cements that react
chemically with water to form the bonding agent
between the aggregate particles in the production of
concrete. Type I (general) cement contains approxi-
mately 20 percent silica, 5 percent alumina, and
60 percent quicklime. Raw materials, such as lime-
stone, shale, clay, or sand, are crushed, milled, and
mixed. The mixture is then calcined in a high-
temperature kiln and pulverized into a fine powder.
Most portions of foundry waste streams could
serve as substitute raw materials. Spent sand would
provide silica, green sand fines would provide alumina
and silica, and slag would provide quicklime and
silica. In addition, any organic impurities present
would be oxidized during calcination. Foundry wastes
have been successfully used as raw material at a
cement plan in Davenport, Iowa, where a local
foundry sends over 100 cubic yards of waste daily
(AFS 1989).
AFS research (1991) has found that use of spent
foundry sand in cement manufacturing results in
increased compressive strengths over control mixes.
This effect increases with the addition of foundry
sand. These findings concur with those of
Borovskaya (1984) and Mchedlov-Petrosyasn et al.
(1983).
AFS research (1991) has also found that using
spent foundry sand as a substitute fine aggregate
material in the manufacturing of concrete resuUXin
decreased compressive strengths when green molding
sands are used. This is probably a result of the fines
and clay particles, which inhibit bond strength.
Nevertheless, many applications for low-strength
concrete exist, such as flowable fill, grouts, and sub-
bases. Finally, AFS found that using chemically
bonded shell sands in concrete mixes slightly
increased observed compressive strengths. Additional
research is necessary to determine how sands using
other types of chemical bonding systems will perform
as a concrete fine aggregate.
Heat Treating Industry
SOURCE REDUCTION OPTIONS FOR CASE
HARDENING BATHS AND SALT POTS
Oxidation products in cyanide-containing bath
media, which is continuously used in case hardening
processes (liquid carburizing, cyaniding, and nitrid-
ing), deplete the activity of the bath which then
becomes hazardous waste. Oxidation products form a
hazardous sludge that is removed frequently (in some
operations on a daily basis) from the bottom of the
pot while the furnace is still at idling temperature.
Pots or work-holding fixtures that are in contact with
case hardening media undergo corrosion and must be
disposed of as hazardous waste every few months to
every few years depending upon service. The follow-
ing options are available to reduce bath and salt pot
waste.
Alter Raw Materials (Bath Composition)
In typical liquid carburizing and nitriding pro-
cesses, molten salts of sodium or potassium cyanides
at concentrations of 30% wt and higher are commonly
used. Liquid carburizing can be accomplished in a
noncyanide bath containing a special grade of carbon
instead of cyanide. In such a bath, carbon particles
are dispersed in the molten salt of carbonates by
mechanical agitation, which is achieved with one or
more propeller stirrers that occupy a small fraction of
the bath. The chemical reaction is not fully
understood, but is thought to involve adsorption of
carbon monoxide or carbon particles. Carbon
25
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monoxide is generated by the reaction between the
carbon and carbonates, which are major ingredients of
the molten salt (ASM 1981).
The adsorbed carbon monoxide is presumed to
react with steel surfaces much as in gas or pack
carburizing. Case depths and carbon gradients are in
the same range as high-temperature cyanide baths, but
there is no nitrogen in the case. Temperatures above
954°C produce more rapid carbon penetration and dp
not adversely affect noncyanide salts because no cya-
nide is present to break down and cause carbon scum
or frothing. Operating temperature is limited primar-
ily by equipment deterioration. Parts that are slowly
cooled following noncyanide carburization are more
easily machined than parts slowly cooled following
cyanide carburization because of the absence of nitro-
gen in noncyanide-carburized cases.
The increased cost of detoxifying cyanide-
containing effluents has led to development of a low-
cyanide salt bath for nitrocarburizing treatments. One
patented process confers sulfur, nitrogen, and presum-
ably carbon and oxygen to the surfaces of ferrous
materials. The process is unique in that lithium salts
are incorporated in the bath composition. Cyanide is
held at very low levels: 0.1 to 0.5 percent. Sulfur
species present in the bath at concentrations of 2 to
10 ppm cause sulfidation to occur simultaneously with
niuiding.
Another low-cyanide alternative is using organic
polymers for bath regeneration. When water quench-
ing is employed, the low level of cyanide permits
easier detoxification. Alternatively, quenching into a
caustic-nitrate salt bath at 260 to 424°C may be used
for cyanide/cyanate destruction.
Clean All Work Placed in the Bath
To protect the bath from external contamination
and to obtain satisfactory case hardening, all work
placed in the bath should be thoroughly cleaned and
free of scale, oxide, entrapped sand, core material,
metal particles, and oil and grease. Acid pickling,
abrasive cleaning with aluminum oxide grit, light
phosphate coating, or simple vapor degreasing can be
used to clean workpieces.
Use Graphite Cover on a Cyanide Bath
To help maintain bath composition and to prolong
its lifetime, a graphite cover should be employed on
the surface of a cyanide bath. Uncovered baths are
exposed to carbonate, which adversely iiiffects bath life
and pot life (enhanced corrosion). Artificial graphite
covers, free of impurities and sulfur, are best. The
higher ash content of natural graphite introduces
impurities into the bath. Furthermore, natural graphite
that contains sulfur causes corrosion of parts.
Dry Work Completely Prior to
Liquid Case Hardening
Loss of bath by spattering during contact with
workpieces is avoided if the workpiece is completely
dry. Even the slight amount of moistuire that may be
deposited on parts and fixtures as a result of atmo-
spheric humidity will cause spatter sit contact with
molten salt.
Remove Impurities
Periodic cleaning increases the longevity of molten
baths. Carbonates, the main oxidation products, are
readily removed by cooling the bath to 454°C and
allowing the precipitated salt to settle to the bottom of
the salt pot. Perforated ladles can be used to spoon
sludge from the bottom.
Minimize Drag-Out
Drag-out refers to the excess bath media that
adheres to the workpiece surface and is carried out of
the media upon withdrawal of the workpiece from the
bath. Drag-out can be minimized by implementing
the following techniques:
Substituting racks for trays. Tray-type fixtures
carry more bath media upon withdrawal from
the bath than a rack, and drainage of the drag-
out is more difficult.
Reducing the speed of withdrawal of workpieces
from the bath and allowing ample drain time.
The faster the workpiece is removed from the
bath, the higher the drag-out will be; the
26
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workpiece should be removed as slowly and as
smoothly as possible; ample time should be
allowed for draining the media back to the tank.
Proper positioning of the workpiece on the plat-
ing rack. The optimal position to minimize
drag-out is best determined experimentally, al-
though the following guidelines are effective:
Orient the surface as close to vertical as pos-
sible
Position the rack so that the longer dimen-
sion of the workpiece is horizontal
Position the rack so that the lower edge is
tilted from the horizontal, ensuring that the
runoff is from a corner rather man an entire
edge.
Replace Pot Lining
Submerged-electrode furnaces will give many years
of service in both cyanide and noncyanide operation
when ceramic pots are replaced by a modified basic
brick.
Alternate Technologies
A number of alternate technologies can be utilized
to minimize or totally eliminate hazardous waste in
the heat treating industry. These include ion (plasma)
nitriding, ion carburizing, and induction heat treatment.
Ion Nitriding and Carburizing. The ion nitriding
process uses an electrically charged gas of ions to
alloy metal surfaces with nitrogen. The process
requires a vacuum vessel in which the workpiece
becomes the cathode in a dc circuit The vessel wall
becomes the anode. The vessel is evacuated to
remove oxygen and other contaminants, and backfilled
with a reactive gas such as an atmosphere containing
nitrogen. When the electric power is turned on, the
gas becomes ionized. Positive ions strike the work-
piece surface and electrons are emitted to the anode
producing a glow discharge around the workpiece.
In steel, this process forms a solid solution of
nitrogen in the surface or develops a compound layer
containing either a gamma prime (Fe4N) or an epsilon
(Fe^N) crystal structure. The hardness, thickness,
and composition of the cases formed can be controlled
by varying the temperature, time, gas composition,
pressure, voltage, and current.
Frequently the vessel is initially filled with an inert
gas. When power is applied, sputtering occurs and
the workpiece is cleaned. Since pads can be sputter
cleaned in the ion nitriding vessel itself, the need for
separate cleaning equipment is eliminated.
Ion nitriding offers numerous advantages over con-
ventional nitriding and carburizing processes.
Increased Control and Improved Properties. In
a conventional nitriding process the furnace is
set at 524°C and the operator controls the length
of time the workpiece is in the furnace. Disso-
ciation rates for white layer control may also be
adjusted by modifying the gas flow rate or by
using an external dissociator. The compound
layer formed often contains a mixture of the
gamma prime and epsilon crystals. It is brittle
and tends to spall or chip off during service.
By contrast, in ion nitriding other parameters
such as temperature, time, gas composition,
pressure, voltage, and current can be controlled.
The process can be used to create a diffusion
zone of nitrogen dissolved in the surface layers
of the workpiece. The result is surface tough-
ness. By varying the parameters, a diffusion
zone and a compound layer of either gamma
prime or epsilon crystal structures can be
achieved resulting in a surface that is both tough
and resistant to wear.
More Uniform Cases. The glow discharge sur-
rounds the part, forming a more uniform case
and making the process ideal for complex parts
such as gears, splines, and shafts.
Negligible Thermal Shock and Distortion. Parts
are heated to the desired temperature at a preset
rate, thus avoiding the thermal shock and distor-
tion prevalent in a salt bath process. Since ion
nitrided parts do not require quench hardening
as in carburizing, another source of distortion
and cracking is eliminated, as is the waste asso-
ciated with the quenching operation.
27
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Broader Treatment Range. The treatment range
is 371 to 649°C. The workpiece is heated to
the desired temperature using the glow
discharge and, in some cases, auxiliary electric-
resistance heating elements. Lower tempera-
tures help maintain workpiece dimensions
during heat treatment Keeping the temperatures
24°C or more below the tempering temperature
of the steel maintains the core hardness of the
parts and eliminates the need for any final heat
treatment.
Faster Cycle Times. Heat treatment cycle times
can be 20 to 50 percent shorter and can favorr
ably affect productivity..
Lower Energy Consumption. Lower tempera-
tures and faster cycle times reduce energy
consumption.
Easier Masking. Mechanical masks are used to
leave chosen areas untreated. This avoids
masking by electroplating and subsequent strip-
ping procedures.
Increased Safety. Safety problems associated
with the toxic, flammable, or explosive salts or
gases used in conventional processes are
eliminated.
Ion carburizing is a process similar to ion nitriding
in which the surface layers of a part are alloyed with
carbon by treating the part in a reaction vessel con-
taining an atmosphere with a high carbon potential.
Unlike ion nitriding, which is an accepted commercial
process, ion carburizing is still in the development
stage.
Induction Hardening. Induction hardening is an
attractive and economic alternative to "neutral" hard-
ening in electric or gas furnaces as well as surface
hardening operations such as gas, pack, or salt bath
carburizing and nitriding. Because no additional
carbon (or nitrogen) is introduced during induction
hardening, steels used in the process must be selected
to have sufficiently high carbon to achieve the desired
hardness levels.
Induction heating relies on electrical currents that
are induced internally in the workpiece material.
.These so-called eddy currents dissipate energy and
bring about heating. The basic components of an
induction heating system are an inditction coil, an
alternating current (ac) power supply, and the work-
piece itself. The coil, which may take different
shapes depending on the required heating pattern, is
connected to the power supply. The flow of ac cur-
rent through the coil generates an alternating magnetic
field, which cuts through the workpiece. This alter-
nating magnetic field induces eddy currents and heats
the workpiece. Moreover, because the magnitude of
the eddy currents decreases with distance from the
workpiece surface, surface heating and heat treating
are possible. In contrast, by allowing sufficient time
for heat conduction, relatively uniform heating pat-
terns can be obtained for through heat treating and
heating prior to metalworking. Careful attention to
coil design and selection of the power supply fre-
quency and rating ensure close control of the heating
rate and pattern.
There are several differences between induction
and traditional heating techniques. The most signifi-
cant difference is that induction heat is generated
within the workpiece. In furnaces, on the other hand,
heat produced by a burning fuel is transported through
the furnace atmosphere via convection and radiation.
Because heat is generated internally, induction pro-
cesses do not require a furnace enclosure or a large
working area.
By judicious choice of coil design, induction heat-
ing can be used to selectively surface harden steel
parts, thereby avoiding masking altogether, as well as
to carry out uniform surface hardening or through
hardening. In addition, dual-frequency induction sur-
face hardening processes have been developed to
effect so-called contour hardening foir parts such as
gears. This type of hardness pattern replicates the
uniform case depth pattern obtained from carburizing,
nitriding, etc. By contrast, the case depths obtained
by this and other induction hardening processes are
substantially greater 0= 0.05 to 0.25 in.) compared to
those obtained by carburizing and nitriding (= 0.002 to
0.020 in.).
SOURCE REDUCTION OPTIONS
FOR QUENCHANT WASTES
Quenching media used in heat treating processes
become hazardous waste when exposed to metal
28
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workpieces contaminated with hazardous residues.
Cyanide-containing heat treating bath contents are
introduced to the quenching media in the form of
drag-out residue left on a workpiece after nitriding,
carburizing, or cyaniding. Sodium or potassium cya-
nide salts form insoluble residue while in contact with
a mineral oil quenchant or dissolve in an aqueous base
quenchant.
Minimize Drag-Out of Molten Salts
Liquid carburizing, liquid cyaniding, and liquid
nitriding salts do not dissolve in, or combine with,
mineral quenching oils. Salt sludge must be removed
periodically either by mechanical means or by filtering
through screens.
Salt quench baths also require desludging of con-
taminants. Carryover of molten salts into brine
quench tanks needs to be controlled so that it does not
exceed 10 percent of salt concentration.
Minimize Drag-Out of Quenchant
The same waste reduction measures identified for
molten salt drag-out apply to the reduction of quench-
ant drag-out. When quenching oil is used, mechanical
removal of surface oil from the workpiece by applying
forced air is efficient.
Control Temperature of Oil Quenchant System
As quenching proceeds, heat is removed from the
workpieces and the temperature of the quenching oil
rises. At high uncontrolled temperatures, oil degrada-
tion or oxidation occurs. Carbonaceous deposits on
quenched parts (sludging) are symptoms of oil break-
down. This effect might change the cooling rate of
the media, causing rejection of treated workpieces. In
addition, carbonaceous deposits are difficult and costly
to remove. A cooling system should be installed as
protection from undesired oil transformations caused
by high temperatures.
Use Modified Materials
To minimize degradation of oil quenchant at high
temperatures (up to 177°C), mineral oil is fortified
with nonsaponifiable additives that increase its
quenching effectiveness and lengthen its useful life.
RECYCLING OPTIONS FOR
QUENCHANT WASTES
Desludge Quenchant Oil
The lifetime of quenching oil can be prolonged by
filtering the oil and recycling it to the original process.
The following contaminants should be removed
frequently:
Carbonaceous materials that may be products of
oil oxidation or carbon fallout encountered in
protective-atmosphere installation
Scale (metal oxides) ,
Sand and other insoluble solids
Precipitated salts from case hardening baths.
The solids can be best removed by appropriate
bypass filters. The most commonly used filtering
media are mineral wool and cellulose, which must be
replaced and disposed of as hazardous waste once
their filtering ability has been exhausted.
Clay filtering media are more expensive, but can
be reused after exhaustion by suitable regeneration.
The regeneration will not remove scale or sand. Clay
media should be carefully selected when fast quench-
ing oils are to be filtered because it is possible to
remove the additives along with the undesirable car-
bonaceous materials. Sintered metal filters that can be
cleaned (backwashed) and reused also can be reused.
Magnetic filters or traps and strainers are useful in
removing scale and other foreign materials. These
types of filters can be easily cleaned and returned to
service. They are especially helpful for preventing
premature filter clogging and for protecting pumps.
In continuous oil quenching, oil is recycled in a
system consisting of the following components:
Quenchant storage-supply tanks and pumps
Coolers and heaters to maintain the desired
temperature of the quenchant
Filters to minimize free carbon and other for-
eign elements
29
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Agitation equipment to obtain uniform quench-
ing and minimize distortion. Oil is usually
agitated by propellers or impeller-type pumps;
compressed air is never used for agitation
because it creates oil foaming problems.
When molten salts precipitate in the oil bath, peri-
odic desludging is necessary. Screens are usually
placed in front of the lines leading to pumps to pre-
vent entry of sludge. The buildup of chlorides carried
over from cyanide containing baths into nitrate-nitrite
quenchants is undesirable. When chloride is allowed
to settle to the bottom of the quench area provided for
gravity separation, the chlorides can be collected in
sludge pans. Periodically, either the pans are removed
or the bottoms of the pans are manually desludged.
Some designs employ continuous filtration of chlo-
rides as the suspended crystals pass through filter
baskets. The operator removes the baskets periodi-
cally to dump the collected chlorides and then returns
them to the furnace. Another technique involves con-
tinuous filtering of higher-melting-point salts by
pumping the contaminated quench salt through a filter
maintained at a lower temperature. The contaminants
are deposited on a wire-mesh basket, and the usable
salts are returned to the quench tank.
De\vater Quenching Oil
Water in quenching oils results in nonuniform or
insufficient hardness of the workpieces. It also cre-
ates heavy foaming and increases the fire hazard.
Water can be removed from an oil bath by:
Raising the temperature above the boiling point
of water (evaporation)
Allowing the water to settle and draining it off
Passing the bath through a centrifuge.
Used quenching oils sometimes emulsify the water
content Such water-containing oils cannot be treated
by draining.
Ultrafilter Water-Polymer Quenchants
Water is commonly used for carbon steel quench-
ing. A water soluble polymer is sometimes used to
modify the quenching rate of a water quench. If
water quenchant is used with a liquid carburizing line,
ultrafiltration can be used for continuous salt removal
(ASM 1981). The polymers may be precipitated by
salt carried into the quench if ultrafiltration is not
used.
Economics
The savings associated with many waste reduction
measures are strong incentives for their implementa-
tion. Less waste means
Decreased waste management costs. This
includes on-site and off-site treatment, storage,
disposal, and recycling facility (TSDR) fees;
state fees and taxes on generators; transportation
costs; and permitting, reporting, and recordkeep-
ing costs.
Raw material cost savings. Minimizing waste
translates into fewer raw materials required per
unit of product.
Insurance and liability savings. This includes
reduced liability for eventual remedial cleanup
of TSDR facilities. There is also less liability
when work place safety is improved.
Operating cost savings from product quality
control. This results from the reduced cost of
scrap, rework, rejects, and quality control
inspections.
Utilities and overhead costs also can be reduced
through waste reduction, although at times, implemen-
tation of waste minimization measures can increase
costs. Converting from a cyanide to a noncyanide
bath in liquid carburizing, for instance, eliminates the
cost of cyanide treatment including chemicals, labor,
and utilities. Installing a magnetic separation system
on the shotblast system to recycle metal dust, how-
ever, can increase the cost of electricity.
Many waste reduction measures involve little or no
capital cost. Improved operating practices can result
in reduced waste management and reduced raw mate-
rials costs. While substantial economic benefits can
often be realized from waste reduction measures that
require no capital expenditures, many measures do
30
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Plant Waste Minimization Assessment Prepared by
Checked By
Date- Proj. No. Sheet of Page of
WORKSHEET WASTE SOURCES
2
Waste Source: Casting
Baghouse dust .
Slags
Spent sands
Combustion emissions
Waste Source: Heat Treating
Process baths
Spills and leaks
Quenching fluids
Emission control dust and vapor
Waste Source: Metal Parts Cleaning and Stripping
Solvents
Alkaline wastes
Acid wastes
Abrasives
Waste water
Air emissions
Other
Waste Source: Surface Treatment and Plating
Spent bath solutions
Filter waste
Rinse water
Spills and leaks
Solid waste
Air emissions
Other
Waste Source: Other Processes
Leftover raw materials
Other process wastes
Types
Pollution control residues
Waste management residues
Other
Significance
Low
'Medium
High
35
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Plant
Date
Waste Minimization Assessment
Proj. No..
Prepared by
Checked By _,
Sheet of Page
of
WORKSHEET
WASTE MINIMIZATION:
CASTING OPERATIONS
Complete for each furnace
Description of furnace and operation performed:.
Identification number:
Type of metals melted:
Additives used:
Feed batch or continuous:
Size or rate of feed:
Method of feed:
Method of slag removal:
Type of refractory:
Replacement frequency of refractory:
Type of emission controls:
Complete for each type of sand used
Type and amount of sand used per year:
Type and amount of binder used per yean
Number of castings per year:
Of the sand used, what percent is recycled?:
What percent ends up as dust?:
What type of emission control devices are employed?:
For heat-cured or reactive binders, are emissions other than dust produced?
36
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Plant wacto Mjnjm
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Page of
WORKSHEET OPTION GENERATION:
4 CASTING OPERATIONS
Meeting format (e.g., brainstorming, nominal group technique)
Meeting Coordinator
Meeting Participants
Suggested Waste Minimization Options
A. Source Reduction Techniques
Alter Raw Material
Convert to Induction Furnace
Use Alternate Desulfurization Agent
Alter Product Specification
Improve Process Control
Keep Waste Segregated
B. Recycling Techniques
Charge Dust to Furnace
Employ Pyrometallurgical Recovery
Employ Rotary Kiln Technology
Employ Electrothermic Shaft Process
Enrich Zinc Oxide
Sell Dust to Cement Plant
Screen Metal from Sand
Reclaim Metal and Sand
Employ Wet Washing/Scrubbing
Employ Dry Scrubbing/Attrition
Employ Thermal Reclamation
Reuse Treated Sand
Sell Sand as Fill Material
Currently
Done Y/N?
Rationale/Remarks on Option
37
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by _
Checked By _
Sheet of
.Page.
of
WORKSHEET
WASTE MINIMIZATION:
HEAT TREATING
OPERATIONS
For each heat treatment system provide
Type of system:
Size of system:
Amount of waste material present: _
Replacement frequency of material:
Type of hazardous material used: _
Emission controls employed:
Method of waste disposal:
Type of quenching fluid/method:
Replacement frequency of quench bath:
How disposed/handled:
38
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by
Checked By
Sheet of Page
of
WORKSHEET
OPTION GENERATION:
HEAT TREATING OPERATIONS
Meeting format (e.g., brainstorming, nominal group technique)
Meeting Coordinator
Meeting Participants
Suggested Waste Minimization Options
Currently
Done Y/N?
Rationale/Remarks on Option
A. Source Reduction Techniques
Alter Raw Materials
Clean Parts Before Treatment
Use Graphite Covers on Cyanide Bath
Dry Work Before Case Hardening
Periodically Clean Baths
Minimize Drag-Out
Replace Pot Linings
Control Temperature of Quench Baths
B. Recycling Techniques
Desludge Quenchant Oil Baths
Dewater Quenchant Oil Baths
Ultrafilter Water Polymer Baths
39
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by _
Checked By _
Sheet of
.Page.
of
WORKSHEET
7A
WASTE MINIMIZATION:
METAL PARJTS CLEANING
AND STRIPPING
Solvent Cleaning
Are solvents used for cleaning purposes?
If so, which of the following are employed?
D Vapor Degreaser
D Spray Chamber
D Covered Solvent Cold Cleaning Tank
D Rag Wipedown
D Brush Scrubbing
D Other
D Uncovered Solvent Cold Cleaning Tank
Spent Chemical Technique (include number & size)
Annual Usage
How are spent solvents managed?
D Biodegradable; disposed of in sewer
D Recycled On Site
Q Recycled Off Site
D Treated or Incinerated On Site
D Treated or Incinerated Off Site
D Other
Annual Costs:
For on-site recycling, is residue hazardous?
How are used rags disposed of?
Annual Costs:
Aqueous Chemical Cleaning
Are cleaners, strippers, surfactants, and detergents used in the plant?
Types of aqueous cleaners used: ;
Chemical Description Active Ingredient
T - "' ~""-- - - - - .. |
Q Alkaline Surfactant Cleaner
D Alkaline Detergent Cleaner
D Alkaline Stripper
D Acid Cleanser .
D Acid Stripper
40
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by _
Checked By _
Sheet of
.Page.
of
WORKSHEET
7B
WASTE MINIMIZATION:
METAL PARTS CLEANING
AND STRIPPING
Process Techniques:
Spray Chamber
Air-sparged Bath
Agitated Bath
Type of Aqueous Cleaner
Sink
Rag Wiping
Brush
Technique (include number & size)
How are spent cleaners managed?
Biodegradable; disposed of in sewer
Transported Off Site
Transported On Site
Annual Costs:
Abrasive Cleaning and Stripping
Annual Costs:
Annual Usage
Describe abrasive cleaning and stripping techniques used (e.g., blasting boxes, buffing machines, etc.):
How are wastes from abrasives techniques managed (e.g., dust, worm discs, etc.):
Annual Costs:
Water Cleaning
Annual Costs:
41
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by _
Checked By _
Sheet of
.Page.
of
WORKSHEET
7C
WASTE MINIMIZATION:
METAL PARTS CLEANING
AND STRIPPING
Size of
Rinse Bath
Application
Continuous
or Still Rinse
Are spray rinse techniques used within the plant?
Temperature
Annual Usage
Describe spray operations:
Is the spray rinsing done in combination with or instead of immersion rinsing?_
Are spent still rinses used as makeups for the process baths?
Is counter-current rinsing employed at the plant?
Describe how it is used. (Give the number of tanks in each counter-current series, the flow rates and the process
chemicals rinsed from the workpieces.): '_ ,,
Water use rate for entire plant rinsing operations: ;
Is deionized water or reverse-osmosis filtered water used for rinsing/cleaning? Where?
Is air sparging or mechanical agitation used in the rinse baths?
List which technique is used in which bath:
Is the spent water recycled or reclaimed?
Q Settled
D Filtered
D Chemically Classified
Is the spent water treated on site?
Is the recycling or treatment residue hazardous?
If yes, how is it managed?
Waste minimization opportunities in metal parts cleaning and stripping:
Potential waste minimization savings of process materials and waste management costs:
Comments:
42
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Plant
Date
WORKSHEET
8
Waste Minimization t
Proj. No.
\ssessment Prei
Che
She
jare'd by
eked By
et of Page of
OPTION GENERATION:
METAL PARTS CLEANING
AND STRIPPING
Meeting format (e.g., brainstorming,
Meeting Coordinator
nominal group technique)
Meeting Participants
Suggested Waste Minimization Options
A. Source Reduction Techniques
General Operating Procedures
Improve Process Controls
Provide Operator Training
Improve Drainage Techniques
Implement Better Storage and Distribution Measures
Other
Solvents
Use Vapor Degreasers
Cover Immersion Tanks
Install Drainboards
Employ Material Substitution
Other
Aqueous Cleaners
Remove Sludge
Use Tank Lids
Other
Abrasives
Use Water-Based Binders
Use Liquid Spray Abrasives
Preclean Workpieces
Other
B. Recycling Techniques
Solvents
Filter Solvents
Distill Solvents
Abrasives
Reuse Blasting Media
Other
Currently
Done Y/N?
Rationale/Remarks on Option
43
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Plant
Date
Waste Minimization Assessment
Proj. No..
Prepared by _
Checked By _
Sheet of
.Page.
of
WORKSHEET
WASTE MINIMIZATION:
METAL SURFACE
TREATING AND PLATING
Complete a worksheet for each process tank
Description of tank function:
Identification number:
Size:
Composition of process solution:
Temperature:
Work volume (square feet of workpiece surface per week):
Quantity of make-up chemicals added per week: ^____
What chemicals are added?:
How much of the make-up volume is due to replenishing drag-out?:
Replenishing evaporative losses?: ,
Is deionized or reverse-osmosis filtered water used in the process baths?:
Are drag-out reduction techniques employed? ._
Which ones? ^__
What is the dump schedule for the process tank? i
Is the process line manual or automatic?
Is rack or barrel plating employed in the tank? ;
What is the production rate of the tank (workpiece surface area per week)?
Are baths air sparged or mechanically agitated?
Are personnel trained to thoroughly drain workpieces above baths before moving them to another baEh?
Are they periodically retrained? , .
Are there spaces between process baths and their rinse tanks that allow chemicals to drip on the floor?
Are process baths filtered to remove particulates?
44
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Plant wacto Minjm
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Page of
WORKSHEET OPTION GENERATION:
1 0 METAL SURFACE TREATING
AND PLATING
Meeting format (e.g., brainstorming, nominal group technique)
Meeting Coordinator
Meeting Participants
Suggested Waste Minimization Options
A. Source Reduction Techniques
Bath Solution Waste Reduction
Reduce Drag-Out, Spills, and Leaks
Provide Efficient Drainage
Control Viscosity and Surface Tension
Filter Bath Solutions
Monitor and Control Bath Solution
Other
Rinse System Design
Incorporate Still Rinse Design
Employ Counter-Current Rinsing
Assure Efficient Drainage
Use No-Rinse Coating
Other
Product Substitution
Substitute Cadmium Plating Alternatives
Substitute Chromium Plating Alternatives
Substitute Cyanide Bath Alternatives
Use Immiscible Rinse
Other
B. Recycling Techniques
Recycle Process Baths
Recycle Rinsewater
Other
Currently
Done Y/N?
Rationale/Remarks on Option
45
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Plant
Date
Waste Minimization Assessment
Proj. No.
Prepared by
Checked By
Sheet of Page.
of
WORKSHEET
11
WASTE MINIMIZATION:
OTHER PROCESSES
Are any metal oxide wastes generated in welding or soldering operations in your plant?
Are any hazardous fluxes used in welding or soldering operations?
How are the above wastes managed?
ADDITIONAL PROCESSES THAT GENERATE WASTE
_Note: If so, they must be managed as hazardous waste.
Process
Type of Waste
Annual Amount
Potential source reduction and recycling opportunities:
Management
Method
Annual Cost of
Management
46
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Plant WastA Minim
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Paqe of
WORKSHEET OPTION GENERATION:
12 OTHER PROCESSES
Meeting format (e.g., brainstorming, nominal group technique)
Meeting Coordinator
Meeting Participants
Suggested Waste Minimization Options
A. Source Reduction Techniques
B. Recycling Techniques
Currently
Done Y/N?
Rationale/Remarks on Option
47
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Appendix A
METAL CASTING AND HEAT TREATING FACILITY ASSESSMENTS:
CASE STUDIES OF PLANTS
In 1990, the California Department of Health Ser-
vices commissioned a waste minimization study,
Waste Audit Study: Thermal Metal Working Industry,
that included assessments of a nonferrous foundry, a
heat treating plant, and a ferrous metal foundry. The
objectives of die study were to:
* Investigate current waste reduction methods
Identify further opportunities to reduce waste.
Results of these waste reduction assessments pro-
vide valuable information about the potential for
incorporating waste reduction technologies into metal
casting and heat treating operations. This appendix
presents summaries of the results of the assessments
performed by California DHS at three such operations.
The summaries presented are largely unedited and
should not be taken as recommendations of the
USEPA; they are provided as examples only. In
addition, the California focus included more than
waste reduction alternatives; it also addressed treat-
ment alternatives that would lead to sludge and waste
water volume reduction. These recommendations are
also included in the following summaries.
The original assessments may be obtained from:
Mr. Benjamin Fries
California Department of Toxic Substances Control
714/744 P Street .
Sacramento, CA 94234-7320
(916) 324-1807.
48
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PLANT A WASTE MINIMIZATION ASSESSMENT
Plant A is a brass foundry (SIC 3432) that manu-
factures cast brass plumbing fixtures. The foundry
was built in 1971. Input copper, lead, tin, and zinc
for brass manufacturing operations come mainly from
recycled automobile radiators.
Process Description
The foundry manufactures 10 to 12 million pounds
per year of brass plumbing fixtures. A "semi-red
leaded brass" alloy is used, consisting of 79 percent
copper, 12 percent zinc, 7 percent lead, and 2 percent
tin. Eighty percent of the new feed materials comes
from used radiators; the remainder is from Mexican-
made ingots. The ingots are frequently out of spec,
but are bought in order to keep a second source of
materials available.
Channel-type induction furnaces are used in the
foundry. Each furnace is heated to 1149°C. There
are two furnace lines, only one of which is in use at
present. Each line consists of three 450 kW,
10,000 Ib capacity melting furnaces arranged in paral-
lel, which feed into a 450 kW, 30,000 Ib holding
furnace. The holding furnace's function, besides
storing the melted metal until it is ready to be poured,
is to help homogenize the melt. Output from the
holding furnace goes into a 17,000 Ib pouring furnace,
which is equipped with 50 kW and 200 kW inductors.
The pouring furnace is a sealed vessel with a positive
air pressure that is used to propel molten metal from
furnace to mold. Molten metal is poured into silica
sand molds on a moving mold car conveyor. The
pour ranges from 15 to 25 Ib, depending on the type
of castings made. Cooling time is 18 minutes.
The molds use fine (#130) silica sands. The sands
are shipped from quarries in Nevada by railroad. The
sand is initially white, but develops a black color due
to high temperature operations. Clay, cornflour, and
wood flour are added during mold making.
Coarse (#55 and #100) sands are used for the mold
core. Coarse sand is required to allow gas to escape.
Linseed oil is added as a binder, kerosene is added to
prevent the core from sticking to the metal, and corn-
flour is added to give the core strength before it is
baked.
Foundry Waste Streams
Hazardous waste streams from foundry operations
include:
Raw slag
Foundry sand
Waste casting metal
Floor sweepings
Furnace fumes
Nonfurnace baghouse wastes
Airborne dust from molding operations
Current Waste Reduction Practices
Most present waste reduction efforts center around
reclaiming metal and sand. While many foundries do
this to some extent, Plant A's multistage efforts far
surpass those of the norm. Plant A is a high-
production foundry that must generate as little metal
waste as possible to remain profitable. Because of the
land ban, and the waste management costs that result
from it, Plant A has also been making increased
efforts in recent years to reduce the size of its waste
streams. Its practices in this regard are documented
below.
RAW SLAG
Raw slag from the furnaces is hazardous because
of the metals it contains. It is sent to a ball mill after
solidifying, which uses cascading steel balls to crush
the chunks of slag. It is then sent through an 8 mesh
(8 wires per inch) screen. Oversized metal grains
caught by the screen are returned to the furnaces for
remelting. The undersized stream, consisting of metal
and slag, goes to a 20 mesh screen. Again, the over-
sized metal caught is remelted, while the undersized
stream is routed to a 40 mesh screen. Oversized
metal caught by this screen is not easily remelted.
Fine metal particles with oxide layers on their surfaces
49
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tend to float on the molten slag in the furnace and not
melt Because of this, the 40 mesh metal stream is
sent to an off-site metal reclaimer. |
The undersized stream that passed through the
40 mesh screen is termed "slag dust," and is sent to
an off-site smelter. Metal extracted during smelting is
made into ingots, which are bought back by the
foundry.
FOUNDRY SAND
Foundry sands are subjected to a series of separa-
tion operations for reclaiming both sand and metal. A
series of screens passes only the fine sands that are
suitable for recycling to molding operations. The
oversized stream is termed "raw core butt," and con-
sists of chunks and grains of coarse core sand, as well
as metal. This stream is sent through vibrating
screens. The oversized stream goes to a ball mill
which crushes the core sand chunks, and then through
an 8 mesh screen. The oversized "ball mill metal"
stream is then sent to a magnetic separator. Any
ferrous metals present are removed and sent to an off-
site reclaimer. The nonferrous stream is remelted in
the furnace.
The undersized stream that passes through the
8 mesh screen goes to a 20 mesh screen. Oversized
ball mill metal is remelted. Undersized "dust," until
recently, was categorized as hazardous or nonhazard-
ous according to its metal content Because of the
new land disposal restrictions, all of the dust is treated
as hazardous. It is presently sent to a TSD facility for
stabilization and landfilling. This service costs $300
per ton of waste. Plant A generates 3,000 tons per
year of foundry sand dust.
WASTE CASTING METAL
Over half the metal poured into a mold is not a
useful part of the casting and needs to be separated
from the casting and remelted. For instance, the
channel made in the sand that allows metal to pour
into the mold fills up with metal that is not in itself a
part of the casting. The top of this filled channel is
conical and is called a sprue head. Underneath is a
filled cylindrical channel called a riser. Underneath
the riser are more extraneous pieces of metal, called
runners and gates. The term "gates" is also used gen-
erically to refer to all of the nonuseiful parts of the
casting.
Most of the gate material breaks off from the cast-
ing during shakeout, is separated on (he "sorting and
breakoff conveyor" by plant personnel, and is sent.
back to the furnace. Castings are senl to the wheela-
brator, which is a blasting cabinet using steel shot to
clean the casting surface. After this, the castings are
inspected. Rejects not meeting plant standards are
sent for a secondary inspection to determine the rea-
son for substandard casting. This data is communi-
cated to the line foremen, so that methods can be
found to reduce rejects in the future. This second
level of inspection is not typical of most plants and is
an important part of Plant A's waste minimization
program. Although most of the metal in a reject cast-
ing can be recycled, some metal and sand finds its
way into the waste stream.
Good castings are sent to the cutoff and grinding
room, where superfluous metal is removed and sent to
the furnace. Next the castings go through a wheela-
brator and then to the polishing shop for additional
cleaning. Operators inspect the castings as they are
working on them. Rejects that were missed in the
previous inspections are sent to the furnace. The ma-
chine shop operators also examine castings and send
rejects, plus borings and fines, to the furnace. Cast-
ings that pass these inspections go to the plating shop
for a surface coating. The castings receive another
inspection by the operators handling them. Castings
rejected because of bad plating are stripped and replat-
ed. If the defect is in the casting itself, it is sent to
the furnace. Finally, the castings are sent to the as-
sembly department Even at this stage, some rejects
are identified and sent back to the .furnace or plating
department
FLOOR SWEEPINGS
Metallic floor sweepings from the furnace area are
sent back to the furnaces for remelting. The metal
reclamation methods described above significantly
reduce the plant's waste and its operating costs. The
financial benefit of internal metal recycling has been
shown to be roughly three times that of sending metal
to an off-site reclaimer.
50
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FURNACE FUMES
Fumes rich in zinc oxide from the metal melted in
the furnaces are collected by baghouses. The foundry
has two 63,000 CFM baghouses (one for each furnace
line), although only one has been in use in recent
years. While sales volume has gone up, the amount
of metal feed to the furnaces has been reduced as a
result of greater process efficiency. Each baghouse
contains 6 sections of bags, which are periodically
shaken. The baghouse dust is collected in fiberglass
sacks and sold to a fertilizer manufacturer. This com-
pany reacts the zinc fraction in the dust with sulfuric
acid to produce zinc sulfate. The zinc sulfate is used
as an additive for almond tree fertilizer.
NONFURNACE BAGHOUSE WASTES
Plant A has several other baghouse waste streams
besides furnace fumes. Airborne dust from the wheel-
abrator blast cleaning machines is trapped in a
20,000 CFM baghouse and then sent to the TSD to be
disposed of as a hazardous waste. Dust from cutoff
and grinding operations is very high in metal content
and is remelted. As was noted earlier, small particles
do not remelt easily if their surfaces are oxidized.
The dust from the cutoff and grinding department is
not oxidized, however, and thus can be sent to the
furnaces.
Airborne dust from coremaking is collected in a
3,500 CFM baghouse, while dust from the sand stor-
age silos is trapped in a small 600 CFM baghouse.
These dusts, which were originally clean sand, are
sent to sanitary landfills to be disposed of as nonhaz-
ardous waste.
AIRBORNE DUST FROM
MOLDING OPERATIONS
The airborne dust from sand molding operations is
potentially hazardous because of its metal content and
because of total suspended participate (TSP) regula-
tions under the Clean Air Act. Airborne dust from
the sand molds is collected by another air emission
control systema "hydrofilter," that includes a wet
scrubber and cyclone separators. Dust laden air is
passed through venturi rods and into the scrubber.
Clean air is vented, after going through de-mist vanes.
Liquids are fed into a settling tank, and "mud" settles
out (with the aid of polyelectrolytes) onto a conveyer
system called a "sludge drag" at the bottom of the
tank. The sludge drag conveyer transports mud up an
incline and out of the tank, then dumps the mud in a
hopper. The mud is reused for making molds. Clean
water from the settling tank goes back to the scrubber.
FEED MATERIALS CONTROL
Stringent measures are taken to prevent aluminum
from getting into the process streams. Soda cans for
instance, are prohibited in the foundry area. This is
because a 0.001 percent aluminum content will "poi-
son" the brass and cause leaks in the fixtures manu-
factured from it.
Future Waste Reduction
Alternatives
Plant A has been paying high waste management
costs for its spent sands, especially since hazardous
waste land disposal restrictions (land ban) have taken
effect. Plant A generates 3,000 tons per year of sand
wastes. Until the land ban took effect, 1,000 tons
were considered hazardous and disposed of at the
TSD at a cost of $200 per ton, or $200,000 per year.
The remainder was disposed of in a sanitary landfill at
a cost of $50 per ton, or $100,000. These costs cover
transportation, disposal, and taxes.
Since the land ban has taken effect, the entire
3,000 ton annual waste stream is treated as hazardous
and sent to the TSD. Fixation of the metal content is
required before landfilling, bringing the total cost of
waste management to $300 per ton, or $900,000
annually.
To reduce these costs, Plant A is examining sand
reclamation and detoxifying options that it hopes to
implement within one year. The options are described
below.
THERMAL SAND RECLAMATION
Plant A is planning to install a 927°C thermo-
calcining reclaimer furnace, to which all waste sands
generated in the plant will be added. The furnace will
burn off the organic contaminants on the sands over a
two-hour cycle. The sand will then be transferred to a
pneumatic scrubber that uses a high velocity air
stream to smash the sand against a plate. This
51
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operation helps to separate the fines that cannot be
recycled from the reusable portion of the Sana's. The
separation process will be completed in a cyclone
scrubber. Eighty percent of the sand wastes are
expected to be reclaimed and reused for mold and
coremaking. The fines, made up of shattered pieces
of sand and clay, as well as a metal fraction, will
comprise the other 20 percent of the stream.
The cost of this option is $600,000. Plant A has
already applied for an operating permit.
DETOXIFICATION OF FINES
Plant A is examining two systems as candidates for
detoxifying fines. The first is a thermal process
developed by Ceramic Bonding, Inc., of Mountain
View, California. It involves mixing the fines with an
alumina-silicate clay material and firing the mixture at
approximately 1093°C. A ceramic material is pro-
duced in which the hazardous metals are physically
and chemically bonded to the alumina-silicate matrix.
The material' has shown excellent resistance to acid
leaching, even under extreme pH conditions. The
ceramic material can either be disposed of as nonhaz-
ardous in a sanitary landfill, or can possibly be mar-
keted as a light-weight construction aggregate. The
suitability of this material for constntiction should be
properly researched. As fill, it may be resistant to
leaching, according to the tests mentioned. However,
as aggregate for concrete, the abrasion during ready-
mix preparation may rupture the ceramic particle
surface that hinders leaching. There may be other
unknowns.
Plant A is also examining an ambient temperature
fixation process that employs a cement and silicates
mixture. This process also has performed well in acid
leaching resistance tests. Both systems are excep-
tional in that they appear to reliably fixate copper in
the sands, which many other methods are not able to
do. The payback period for the combination thermal
sand reclamation system and detoxification system
appears to be approximately one year,
52
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PLANT B WASTE MINIMIZATION ASSESSMENT
Plant B is a commercial heat treating plant
(SIC 3398) designed for handling ferrous and non-
ferrous metal workpieces. The plant employs 140
workers and was established in 1940. Stainless steel,
carbon steel, aluminum, and titanium alloys are heat
treated at the plant. Machined parts ranging in weight
from a few pounds up to 20 tons are delivered for
heat treating from numerous suppliers.
This waste minimization assessment focuses on fer-
rous metal heat treating, which comprises the major
share of the plant's business. Heat treating ferrous
metals includes the following operations:
Austenitizing
Quenching
Tempering
Sandblasting
Aqueous parts cleaning '
Electroplating
Stripping
Testing
Air cooling
Waste minimization measures are included in the
following descriptions of these processes.
Austenitizing
Austenitizing is performed hi vertical gas-fired
gantry type furnaces in a batch mode. The largest
parts (missile parts) weigh up to 20 tons and are
treated in a special furnace. The furnace has a
walking-beam construction consisting of two sets of
support rails: one stationary and the other movable.
The austenitizing process is performed by heating the
part to 885°C for approximately 2.5 hours and subse-
quently holding the part at this temperature for
another 2.5 hours. The temperature is controlled with
a thermocouple sensor. The temperature and holding
time are the most critical parameters in the austenitiz-
ing process. Excessively high austenitizing tempera-
tures or abnormally long holding times, may result in
distortion, abnormal grain growth, loss of ductility,
and low strength. Underheating may result in low
hardness and low wear resistance. Gas-fired radiant-
tube-heating is used in this process. This methpd of
heating protects the work chamber from the products
of natural gas combustion.
Gas-fired furnaces generate a flue gas that is
emitted directly to the atmosphere. City water is used
to cool the pit that gives access to the walking-beam
construction furnace. Because a workpiece is pro-
cessed without direct contact with the furnace refrac-
tory material, no metal oxides or other contaminants
are transferred to the water mat evaporates from the
pit. Thus, the water does not become hazardous
waste. The refractory linings of the furnaces were
changed once hi the past 40 years from asbestos to a
fiberglass type of material. No hazardous waste is
generated on a continuous basis from this process.
Substitution of a nonhazardous lining hi furnaces was
the only waste minimization measure employed so far
hi this process. Smaller workpieces are treated in
stationary gas-fired Gantry type furnaces that generate
the same type of nonhazardous wastes described
above.
Quenching
Workpieces can be quenched in one of three sepa-
rate sumps filled with oil, water, or molten salt media.
The largest metal workpieces from walking-beam fur-
naces are quenched hi a sump filled with molten salts
of potassium and sodium nitrates. Metal parts are
transferred to the sump with an overhead crane. After
quenching is completed, the workpieces with their salt
residues are returned to the furnace for tempering.
Most carbon steel workpieces are quenched in oil
at temperatures from 24 to 60°C. Some stainless steel
parts are quenched in the water at ambient tempera-
ture. If the same operation was performed with a car-
bon steel part, it would break as a result of the very
drastic quenching environment. Other ferrous alloys
are quenched in a molten salt bath at approximately
204°C. All parts quenched in oil are transported by
crane to a hot water wash station located hi the
53
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INPUT MATERIALS AND WASTE STREAMS
The molten salt quenchant consists of potassium
nitrate and sodium nitrate mixed in the proportion of
1:1. Make-up salts are periodically added to the bath
to maintain the required volume of quenching media.
Since 1971, the molten salt media has not been
changed or disposed of. There has been no need to
remove solids that have settled since then.
Mineral oil is used as another quenchant. The
waste oil is collected in an underground clarifier at a
water wash station and removed periodically by a con-
tractor for off-site recycling. An average trucklbad
contains approximately 5 percent oil and 95 percent
wastewater. Plant B generates about 4300 gallons of
waste oil every 6 to 7 months.
Water is used as the quenchant where drastic
quenching does not result in excessive distortion or
cracking of the workpiece. The water quenching
sump is very rarely used, and no need for cleaning
this sump has been experienced in the last sevpral
years.
WASTE REDUCTION ALTERNATIVES
Source reduction measures for quenchant waste
could include:
Substitution of conventional quenching oil for
less viscous "fast" quenching oil (a mineral oil
blend containing proprietary additives), resulting
in decreased drag-out of oil on workpieces and,
consequently, lowering oil consumption
Addition of antioxidants to retard oxidation of
the quench oil
Use of an air blower for mechanical removal of
quenchant from the surface of a workpiece
Increasing drain time of workpieces
Recycling quench oil baths could also minimize
waste oil generation and could be achieved by
'mechanical or thermal conditioning to remove the
following contaminants:
Scale
Carbonaceous sludges that are products of oil
oxidation
Other insoluble solids, such as sand
Water
Soluble compounds, such as carbon dioxide
removed in thermal conditioning
Contaminants can be removed by filtering, evapo-
rating, or draining. Solids can besf, be removed by
appropriate bypass filters. The choice of filtering
medium for removing solids is important The most
commonly used filtering media are mineral wool and
cellulose, which must be replaced after their filtering
ability has been exhausted. Clay filtering media are
more expensive than the above types, but can be
regenerated and reused after exhaustion. However,
regeneration will not remove scale or sand. Clay
media should be carefully selected when fast quench-
ing oils are to be filtered, because it is possible to
remove necessary additives in the oil along with unde-
sirable carbonaceous materials. Sintered metal filters;
also can be used; these filters can be cleaned and
reused.
Magnetic filters, traps, and strainers are useful in
removing scale and other foreign materials. These
types of filters can be easily cleaned and returned to
service. They are especially helpful for preventing
premature filter clogging and for protecting pumps.
Water can be removed by filtering or centrifuging,
but these methods are expensive and are rarely used.
Usually, bulk water is removed by draining and sus-
pended water is removed by heating. Carbon dioxide
is also removed by heating.
The waste oil collected in underground clarifiers is
sent for off-site recycling. On-site recycling such as
gravity oil/water separation and subsequent
mechanical/thermal conditioning might be considered
for future quench oil recovery.
54
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Tempering
Steel is tempered by reheating the workpiece after
quenching to obtain specific values of mechanical
properties (e.g., ductility and toughness) and to relieve
quenching stresses and ensure dimensional stability.
Metal parts, after being quenched, undergo tempering
in gas-fired furnaces with forced air atmospheres and
temperatures from 371 to 704°C. The flue gas is
vented to the atmosphere. No hazardous waste is gen-
erated in this process.
Sandblasting
Sandblasting at Plant B is performed indoors in
four sandblasting booths. One baghouse collects parr
ticulates from all these systems. Twenty-five tons a
month of sand is supplied to the location. Spent sand
is disposed of off site by the sand supplier.
Future measures for reducing the quantity of spent
sand might include:
Recycling silica-based dust
Detoxifying hazardous sand with sodium silicate
and calcium oxide technology by means of
stabilization
Reducing the use of raw sand by optimizing
feed control system
Plating and Stripping
Plating is employed for some parts that must be
protected by a coating that is impervious to the car-
burizing atmosphere in the furnace. Copper plating is
widely used for this purpose because it is relatively
easy to apply, machinable, noncontaminating to fur-
nace atmospheres, and amenable to stripping by
immersing a part in a stripping solution. Most, if not
all, of the copper plate may be removed in the course
of subsequent machining operations.
Copper electrostriking operations are performed on
some steel and other ferrous alloy workpieces to opti-
mize the copper electroplating process, which is per-
formed prior to austenitizing. After this, a metal part
typically undergoes austenitizing, molten salt quench-
ing, tempering, air cooling, stripping, sandblasting,
and testing.
The following unit operations are performed in
sequence at the electroplating/stripping site:
.Alkaline cleaning
Rinsing with tap water
Acid cleaning
Rinsing with tap water
Striking
Electroplating
Stripping
INPUT MATERIALS AND WASTE STREAMS
Input materials include alkaline cleaner, weak acid
solution, copper cyanide baths for striking and plating,
and copper stripping solution. Alkaline cleaner is
employed to remove soil from metal parts, and acidic
cleaner is used to remove dust and scale.
All except acidic wastes are collected for batch
treatment in a 6,500 gallon tank. One strip tank
(1,200 gallons) is emptied every 1 to 1.5 months. The
total quantity of hazardous waste generated at this site
is equal to approximately 6,500 gallons every three
months.
WASTE REDUCTION ALTERNATIVES
On a volume basis, contaminated rinsewater
accounts for the majority of plating process waste.
Rinsewater is used to wash off the drag-put from a
workpiece after it is removed from a bath. By mini-
mizing the amount of drag-out carried from a plating
or cleaning bath to a rinsing bath, a smaller amount of
water is needed to rinse off the workpiece. As a
result, less of the plating solution constituents leave
the process, which ultimately produces savings in raw
materials and treatment/disposal costs.
Drag-out minimization techniques that can be
employed include:
Reducing the speed of withdrawal of the work-
piece from solution and allowing ample drainage
time. Usually, 30 seconds allows most of the
drag-out to drain back to the tank.
55
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Using wetting agents to lower the surface ten-
sion of plating solutions. Applied in only small
amounts, wetting agents can lower solution Sur-
face tension enough to reduce drag-out by up to
50 percent Only nonionic wetting agents,
which will not be degraded by electrolysis in the
plating bath, should be employed.
Proper positioning of the workpiece on a plating
rack facilitates dripping of drag-out into the
bath. The position of any object that will mini-
mize carryover of drag-out is best determined
experimentally, although the following guide-
lines are found to be effective:
Orient the surface as close to vertical as
possible
Position the rack so that the longer dimen-
sion of the workpiece is horizontal
Position the rack so that the lower edge is
tilted from the horizontal to assure that
runoff is from a corner rather than an entire
edge
For regularly shaped parts that do not contain
oddly shaped objects, fog or spray nozzles can be
employed to rinse contaminants from the surface. A
fog nozzle uses water and air pressure to produce a
fine mist. Less water is used than with a conventional
spray nozzle.. It is possible to use a fog nozzle
directly over a heated plating bath to rinse the work-
piece. This permits simultaneous rinsing and replen-
ishment of the evaporated losses from the tank.
Spent cleaning solutions might be disposable as
nonhazardous wastes if they are kept segregated from
plating wastes and neutralized. Another promising
waste minimization measure is replacing cyanide
plating solutions with cyanide-free pyrophosphate
copper plating solutions.
WASTEWATER TREATMENT
Sodium hypochlorite solution is used for batch
treatment of wastewater to oxidize the cyanides at
alkaline conditions. Treated water is sampled and
analyzed for cyanide concentration. Wastewater with
a high copper content is then pH-adjusted for opti-
mum Cu(OH)2 precipitation, and pumped to a plate
and frame type filter press. Filtrate is discharged to
the sewer system. Six to seven drums (500 Ibs each)
of sludge are disposed of off site as hazardous waste
every 2 to 3 months.
Plant B is currently investigating the possibility of
off-site copper recovery from the sludge. One option
would be to contract these sludges with copper recy-
clers. Some recyclers specify minimum metal con-
tents in the sludge cake and a minimum tonnage per
year for the waste to be accepted for reclamation.
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PLANT C WASTE MINIMIZATION ASSESSMENT
Plant C is an iron foundry (SIC 3321) established
in 1946. It manufactures gray, ductile, and alloy iron
castings from scrap iron including scrap engines.
Plant C typically employs 155 workers, although this
number can fluctuate tip to 320 employees. Daily
consumption of scrap metal is estimated at approxi-
mately 100 tons per day. Eight hundred tons of waste
are generated a month for off-site disposal, including
approximately 400 tons of foundry sand and at least
300 tons of refractory material that are disposed of as
nonhazardous waste. The balance consists of hazard-
ous waste generated in form of dust and sludge from
air emission control systems.
The iron casting process at Plant C consists of the
following operations:
Scrap metal melting
Core making
Molding and core setting
Pouring molten metal
Shakeout
Surface cleaning
Some ductile iron castings undergo annealing, a
heat treating operation. The foundry produces cast-
ings by pouring molten metal into molds consisting of
molding sand and core sand. Once the casting has
cooled and hardened, it is separated from the mold
and core materials in the shakeout process. The cast-
ings are cleaned, inspected, and shipped for delivery.
Melting
The foundry employs two types of furnaces for
melting scrap metal: five induction furnaces and one
cupola furnace.
System No. 1 consists of two "Ni-resist" electric
induction furnaces for production of heat resistant
alloy. In these, low carbon steel charge is carburized
to increase its carbon content; and nickel, molybde-
num, and chromium are added. The product castings
from these furnaces are classified as heat-resistant
iron-based alloys. Total charge to the system'is equal
to 100 tons per year.
System No. 2 consists of three large induction fur-
naces with holding capacities of 9, 3.5, and 3.5 tons
for production of ductile iron. The feed to this system
consists of scrap steel, pig iron returns, granular car-
bon, silica, and magnesium alloy. The charge is
heated electrically to 1593°C.
The cupola furnace at Plant C is used to melt
motor blocks. The furnace operates 3 to 4 days a
week, 9 hours a day, and has been in operation since
1947 (one of the oldest pieces of equipment at the
foundry). It is used for production of gray iron
castings. Materials used in the melting operation
include scrap metal (such as engine blocks), fluxes,
coke, and refractory material.
Fluxes include limestone, fluorspar and soda ash.
These are used as conditioners for slag formed in the
melted charge to facilitate its removal from the
furnace.
The coke is used as a source of fuel for the cupola.
Refractory material that can withstand high tempera-
tures is used to line the furnace. The refractory mate-
rial is subject to deterioration during the foundry
process and therefore must be replaced periodically.
WASTE STREAMS
The off gases from the induction furnaces in Sys-
tem No. 2 (ductile iron production) are vented to the
atmosphere. Furnace refractory material is disposed
of off site as nonhazardous waste. Furnace slag is
also disposed of as nonhazardous material.
The off gases from two Ni-resist induction furnaces
in System No. 1 (heat resistant alloy production) are
vented to the atmosphere. The slag generated in the
melting process hi these furnaces is classified as haz-
ardous waste because of its heavy metal toxicity char-
acteristics (high nickel and chromium concentrations).
An estimated 1 to 2 tons of hazardous slag waste are
generated annually. Furnace refractory material from
57
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the Ni-resist furnaces is disposed of as nonhazardous
waste.
Wastes generated in cupola melting operations
include:
Dust and sludge from emissions control system
Slag
Bottom drop and sweepings
Spent refractories
The major waste stream from the melting operation
is refractory lining. Quantities of more than 300 tons
a month are generated. All the waste except refrac-
tory linings generated in this process are classified as
hazardous.
Emission control residuals are generated at the rate
of 1,000 to 1,500 Ibs per week. They exceed toxicity
characteristics for lead and zinc primarily. Gray kon
is melted at approximately 1482°C. The melting
points for toxic metals in the furnace is much lower.
Lead, for example, melts at 327°C. As the metal feed
is melted, the lead, zinc, and cadmium tend to volati-
lize and are collected by the emission control system.
Emissions from cupola furnaces are controlled by a
cyclone scrubber, which removes large particulates,
and the baghouse, which separates fines.
WASTE REDUCTION ALTERNATIVES
Plant C has implemented two successful waste
minimization measures that include:
On-site recycling of slag from two Ni-resist
induction furnaces
Detoxification of residuals in the cupola furnace
emission control system
As of July 1988, Plant C has been recycling the
slag from two Ni-resist electric induction furnaces by
charging the slag to the cupola furnace.
This slag from Ni-resist furnaces plays the role of
scavenger of trace metal elements from the cupola
furnace charge. The cupola slag has become a non-
hazardous waste since most toxic metals are scav-
enged from the slag. Forty cubic yards (3-4 tons) of
slag a month are sent for application at equestrian
trails.
Full-scale experiments on detoxification of resid-
uals from the cyclone scrubber ;are in progress.
Silicate treatment technology is being employed to
immobilize heavy metals (Pb, Zn, Cd, and other ele-
ments) carried over with flue gases and particulates
from the stack of the cupola furnace. A 12.5 percent
sodium silicate solution is injected at the rate of
1.5 GPM into the treatment spray nozzle section of
the quench zone in the stack, where the temperature
exceeds 704°C. Hydrated lime is iriso added. The
chemical costs for this process are estimated at $200 a
day.
The total concentration ranges of heavy metals in
the wet scrubber residuals before treatment are:
Zn: 500- 1,595 mg/kg
Pb: 605- 6,085 mg/kg
Cd: 0.8- 7.5 mg/kg
Waste extraction test (WET) results after 48 hours of
extraction varied as follows on silicate treated
materials:
Zn: 0.3 - 44 mg/1
.Pb: 20.1 - 230 mg/1
Cd: < 0.1 mgA
Soluble threshold limit concentrations for metals
are as follows: . i
Zn:
Pb:
Cd:
250 mg/1
5 mg/1
1.0 mg/1
Stack temperature is a critical parameter in the
silicate treatment process. Efficiency of treatment
increases when temperatures are above 704°C. The
cupola furnace stack temperature is unfortunately not
stable throughout the process. This results in variance
in the efficiency of particulate treatment. The plant is
currently attempting to improve this system.
Other possible waste reduction measures under
consideration for potential implementation are as
follows:
Off-site recycling to a smelter of lead-containing
wastes. The smelter would pick up the material
for the cost of $250 per ton.
58
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Internal recycling by a combination of furnace
dust with sand for reuse in the mold making
process. Detoxification of sand with sodium
silicate and calcium oxide technology followed
by formation of a mold with detoxified sand as
backing and new sand facing of the mold-metal
interface.
Core Making
Core making involves coating a refractory material
(silica sand) with binder, compacting the coated sand
into the desired shape, and then curing (hardening) the
compacted mass so that it can be handled.
Cores are used to produce internal cavities within a
casting. The cores are composed of silica sands with
small percentages of organic binders. Oil binders and
synthetic resin types are used at Plant C. Oil binders
are vegetable oils. Resin binders include phenolics
and phenol-formaldehydes. Cores must possess the
characteristics of strength, hardness, and collapsibility.
Often the cores are removed within a casting through
a small orifice and, therefore, sand must collapse after
the casting solidifies.
The following processes of core making are
employed at Plant C:
Shell core process (heat cured process)
SO2 core process (cold box process)
Core oil process (oven bake heat-cured process)
In the shell core process, precoated shell sand is
used. The precoated binder is a synthetic phenol-
formaldehyde type of resin. A gas-fired shell core
machine is used to form cores at 232°C. This process
requires the core box to be heated (177 to 288°C)
prior to introduction of the prepared sand.
In the SO2 core process, the sand is mixed with
binder and catalyst The SO2 gas activates the cata-
lyst to bind the sand. This cold-cured process utilizes
sulfur dioxide gas that is forced through the com-
pacted sand mixture to cure the core.
In the oven bake core process, the sand is mixed
with vegetable oil and ferrous oxide. The core box is
filled normally with the material, and cores are baked
in an oven at 232°C.
WASTE STREAMS
The excess of sulfur dioxide used in the SO2 core-
making process is controlled by the caustic soda
scrubber. Fifty percent makeup solution of NaOH is
used to replenish the scrubber. Approximately
155 gallons of scrubber waste are generated daily and
are discharged to the sanitary sewer system at con-
trolled pH range.
Additional waste streams are handled as follows:
Shell core machine off gases are vented to the
atmosphere
The core oven gases are combusted in an
afterburner
Solid core wastes are blended with foundry sand
and disposed of off site as nonhazardous waste
Mold Making
Molding sand is compacted around a pattern of the
casting that is to be produced. Green sand is used at
Plant C to form molds.
Green sand is prepared from:
Green sand mixture (85-95%) - inert silica
Bentonite clay (4-10%)
Carbonaceous material (2-10%)
Water (2-5%)
Sand, clay, water, and carbonaceous materials are
charged into the mixing device. These devices are
called either mullers or mixers. Three mullers at
Plant C prepare the feed for mold making and core
setting equipment. Coping/dragging, squeezing, and
automatic mold making are used to make molds.
WASTE STREAMS
Waste streams generated in the molding process are
in the form of dusts and sludges that have been col-
lected in the air pollution control system. Large sand
clumps are also formed that are screened out of the
molding sand recycle systems or that are cleaned from
the castings.
59
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WASTE REDUCTION ALTERNATIVES
No hazardous waste is generated in the mold mak-
ing operation. Foundry spent sand is disposed of off
site as nonhazardous waste.
Pouring
The molten metal is transported to the pouring area
in a transfer ladle, where it is poured into the pouring
ladle and into the molds. The poured molds are
allowed to cool and the solidified castings are
removed from the mold, rough cleaned of mold mate-
rial, and allowed to cool until the cast metal is cold
enough to handle. The smoke emitted is exhausted to
the atmosphere. The "sweepings" generated hi the
pouring process are mixed with foundry sand and
disposed off site as nonhazardous waste.
Shakeout
The shakeout process is performed to separate sand
from the casting. Sand that has had its binder fully
degraded in the pouring process is mixed with mold-
ing sand for recycling. The core butts (partially
decomposed core sands) are crushed and recycled
back into the molding sand process or they are taken
directly to the landfill for disposal along with broken
or off-spec cores and core recovery sweepings. The
molding and core sand wastes account for about
50 percent of the total waste generated by the foun-
dry. The company pays $100,000 a year for sand dis-
posal. The air emission control system consists of
four baghouses to collect the foundry sand. The
majority of foundry sand is classified and disposed of
off site as nonhazardous waste. The sand from Sys-
tem No. 2, with three large induction furnaces, is
clas'sified as a hazardous material due to high zinc
concentrations. Two hundred pounds per week of
hazardous foundry sand are generated in System No. 2
paniculate collection equipment.
WASTE REDUCTION ALTERNATIVES
Since 1988, the hazardous sand from System No. 2
has been segregated from other foundry spent sand
and recycled as a feed component to the cupola fur-
nace in the quantity of 1,500 Ibs per week. This sand
becomes a component of the cupola furnace slag and
is sold for filling equestrian trails. The company
would need to spend $250 per toni for hauling this
sand to a smelter if the waste minimization measure
was not employed.
Surface Cleaning
Polishing wheels are used to clean castings. The
baghouse dust wastes are mixed with foundry sand
and disposed of off site as nonhazardous wastes.
Heat Treating
Some ductile iron workpieces undergo an annealing
process. Annealing is a heat treating operation.
Workpieces are heated to 843°C for six hours and
held at this temperature followed by cooling at an
appropriate rate, primarily to soften metallic materials.
The entire annealing cycle takes from 18 to 24 hours.
Three direct-fired (natural gas fired) box type fur-
naces operate in batch mode. No hazardous waste is
generated in this process. Refractory furnace lining is
the only waste generated periodically at this location
and is disposed of as nonhazardous waste.
60
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Appendix B
WHERE TO GET HELP:
FURTHER INFORMATION ON POLLUTION PREVENTION
Additional information on source reduction, reuse
and recycling approaches to pollution prevention is
available in EPA reports listed in this section, and
through state programs and regional EPA offices
(listed below) that offer technical and/or financial
assistance in the areas of pollution prevention and
treatment.
Waste exchanges have been established in some
areas of the U.S. to put waste generators in contact
with potential users of the waste. Twenty-four
exchanges operating in the U.S. and Canada are listed.
Finally, relevant industry associations are listed.
U.S. EPA Reports on
Waste Minimization
Facility Pollution Prevention Guide.
92/088.*
EPA/600/R-
Waste Minimization Opportunity Assessment Manual.
EPA/625/7-88/003.*
Waste Minimization Audit Report: Case Studies of
Corrosive and Heavy Metal Waste Minimization Audit
at a Specialty Steel Manufacturing Complex. Execu-
tive Summary. EPA No. PB88-107180.**
Waste Minimization Audit Report: Case Studies of
Minimization of Solvent Waste for Parts Cleaning and
from Electronic Capacitor Manufacturing Operation^
Executive Summary. EPA NO. PB87-227013.**
* Available from EPA CERI Publications Unit (513) 569-7562,
' 26 West Martin Luther King Drive, Cincinnati, OH, 45268.
** Executive Summary available from EPA, CERI Publications
Unit, (513) 569-7562, 26 West Martin Luther King Drive, Cin-
cinnati, OH, 45268; full report available from the National
Technical Information Service (NTIS), U.S. Department of
Commerce, Springfield, VA, 22161.
Waste Minimization Audit Report: Case Studies of
Minimization of Cyanide Wastes from Electroplating
Operations. Executive Summary. EPA No. PB87-
229662.**
Report to Congress: Waste Minimization, Vols. I and
II. EPA/530-SW-86-033 and -034 (Washington, D.C.:
U.S. EPA, 1986).***
Waste MinimizationIssues and Options, Vols. I-III.
EPA/530-SW-86-041 through -043. (Washington,
D.C.: U.S. EPA, 1986.)***
The Guides to Pollution Prevention manuals*
describe waste minimization options for specific
industries. This is a continuing series Which currently
includes the following titles:
Guides to Pollution Prevention:
Industry. EPA/625/7-90/005.
Paint Manufacturing
Guides to Pollution Prevention: The Pesticide For-
mulating Industry. EPA/625/7-90/004.
Guides to Pollution Prevention: The Commercial
Printing Industry. EPA/625/7-90/008.
Guides to Pollution Prevention: The Fabricated
Metal Industry. EPA/625/7-90/006.
Guides to Pollution Prevention for Selected Hospital
Waste.Streams. EPA/625/7-90/009.
Guides to Pollution Prevention: Research and Educa-
tional Institutions. EPA/625/7-90/010.
Guides to Pollution Prevention: The Printed Circuit
Board Manufacturing Industry. EPA/625/7-90/007.
*** Available from the National Technical Information Service as
a five-volume set, NTIS No. PB-87-114-328.
61
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Guides to Pollution Prevention:
Industry. EPA/625/7-91/017.
Guides to Pollution Prevention:
Industry. EPA/625/7-91/012.
The Pharmaceutical
The Photoprocessing
Guides to Pollution Prevention: The Fiberglass Rein-
forced and Composite Plastic Industry.
EPA/625/7-91/014.
Guides to Pollution Prevention: The Automotive
Repair Industry. EPA/625/7-91/013.
Guides to Pollution Prevention: The Automotive
Refinishing Industry. EPA/625/7-91/016.
Guides to Pollution Prevention: The Marine Mainte-
nance and Repair Industry. EPA/625/7-91/015.
Guides to Pollution Prevention:
ment Repair Shops.
Guides to Pollution Prevention:
Industry.
Mechanical Equip-
The Metal Finishing
U.S. EPA Pollution Prevention Information Clearing
House (PPIQ: Electronic Information Exchange Sys-
tem (EIES)User Guide, Version 1.1. EPA/600/9-
89/086.
Waste Reduction Technical/
Financial Assistance Programs
The EPA Pollution Prevention Information Clear-
inghouse (PPIC) was established to encourage waste
reduction through technology transfer, education, and
public awareness. PPIC collects and disseminates
technical and other information about pollution pre-
vention through a telephone hotline and an electronic
information exchange network. Indexed bibliographi-
es and abstracts of reports, publications, and case
studies about pollution prevention are available. PPIC
also lists a calendar of pertinent conferences and semi-
nars, information about activities abroad, and a direc-
tory of waste exchanges. Its Pollution Prevention
Information Exchange System (PIES) can be accessed
electronically 24 hours a day without fees.
For more information contact:
PIES Technical Assistance
Science Applications International Corp.
8400 Westpark Drive
McLean, VA 22102
(703) 821-4800
or
U.S. Environmental Protection Agency
401 M Street S.W.
Washington, D.C. 20460
Myles E. Morse '
Office of Environmental Engineering and
Technology Demonstration
(202) 475-7161
Priscilla Flattery
Pollution Prevention Office
(202) 245-3557
The EPA's Office of Solid Waste and Emergency
Response has a telephone call-in wervice -to answer
questions regarding RCRA and Superfund (CERCLA).
The telephone numbers are:
(800) 242-9346 (outside the District of Columbia)
(202) 382-3000 (hi the District of Columbia)
The following programs offer technical and/or
financial assistance for waste minimization and
treatment.
Alabama
Hazardous Material Management and Resource
Recovery Program
University of Alabama
P.O. Box6373
Tuscaloosa, AL 35487-6373
(205) 348-8401
Department of Environmental Management
1751 Federal Drive
Montgomery, AL 36130
(205)271-7914
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Alaska
Alaska Health Project
Waste Reduction Assistance Program
431 West Seventh Avenue, Suite 101
Anchorage, AK 99501
(907) 276-2864
Arizona
Arizona Department of Economic Planning and
Development
1645 West Jefferson Street
Phoenix, AZ 85007
(602)255-5705
Arkansas
Arkansas Industrial Development Commission
One State Capitol Mall
Little Rock, AR 72201
(501) 371-1370
California
Alternative Technology Section
Toxic Substances Control Division
California State Department of Health Services
714/744 P Street
Sacramento, CA 94234-7320
(916) 324-1807
Pollution Prevention Program
San Diego County Department of Health Services
Hazardous Materials Management Division
P.O. Box 85261
San Diego, CA 92186-5261
(619) 338-2215
Colorado
Division of Commerce and Development Commission
500 State Centennial Building
Denver, CO 80203
(303) 866-2205
Connecticut
Connecticut Hazardous Waste Management Service
Suite 360
900 Asylum Avenue
Hartford, CT 06105
(203) 244-2007
Connecticut Department of Economic Development
210 Washington Street
Hartford, CT 06106
(203)566-7196
Delaware
Delaware Department of Community Affairs &
Economic Development
630 State College Road
Dover, DE 19901
(302) 736-4201
District of Columbia
U.S. Department of Energy
Conservation and Renewable Energy
Office of Industrial Technologies
Office of Waste Reduction, Waste Material
Management Division
Bruce Cranford CE-222
Washington, DC 20585
(202) 586-9496
Pollution Control Financing Staff
Small Business Administration
1441 "L" Street, N.W., Room 808
Washington, DC 20416
(202) 653-2548
Florida
Waste Reduction Assistance Program
Florida Department of Environmental Regulation
2600 Blair Stone Road
Tallahassee, FL 32399-2400
(904) 488-0300
Georgia
Hazardous Waste Technical Assistance Program
Georgia Institute of Technology
Georgia Technical Research Institute
Environmental Health and Safety Division "
O'Keefe Building, Room 027
Atlanta, GA 30332
(404) 894-3806
Environmental Protection Division
Georgia Department of Natural Resources
205 Buder Street, S.E., Suite 1154
Atlanta, GA 30334
(404) 656-2833
63
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Guam
Solid and Hazardous Waste Management Program
Guam Environmental Protection Agency
U&E Harmon Plaza, Complex Unit D-107
130 Rojas Street
Harmon, Guam 96911
(671) 646-8863-5
Hawaii ;
Department of Planning & Economic Development
Financial Management and Assistance Branch
P.O. Box 2359
Honolulu, HI 96813
(808) 548-4617
Idaho
IDHW-DEQ
Hazardous Materials Bureau
450 West State Street, 3rd Floor
Boise, ID 83720
(208) 334-5879
Illinois
Hazardous Waste Research and Information Center
Illinois Department of Energy and Natural Resources
One East Hazelwood Drive
Champaign, IL 61820
(217) 333-8940
Illinois Waste Elimination Research Center
Pritzker Department of Environmental Engineering
Alumni Memorial Hall, Room 103
Illinois Institute of Technology
3201 South Dearborn
Chicago, IL 60616
(312) 567-3535
Indiana
Environmental Management and Education Program
School of Civil Engineering
Purdue University
2129 Civil Engineering Building
West Lafayette, IN 47907
(317) 494-5036
Indiana Department of Environmental Management
Office of Technical Assistance
P.O. Box 6015
105 South Meridian Street
Indianapolis, IN 46206-6015
(317) 232-8172
Iowa
Center for Industrial Research and Service
Iowa State University
Suite 500, Building 1
2501 North Loop Drive
Ames, IA 50010-8286
(515) 294-3420
Iowa Department of Natural Resources
Air Quality and Solid Waste Protection Bureau
Wallace State Office Building
900 East Grand Avenue
Des Moines, IA 50319-0034
(515) 281-8690
Waste Management Authority
Iowa Department of Natural Resources
Henry A. Wallace Building
900 East Grand
Des Moines, IA 50319
(515) 281-8489
Iowa Waste Reduction Center
University of Northern Iowa
75 Biology Research Complex
Cedar Falls, IA 50614
(319) 273-2079
Kansas
Bureau of Waste Management
Department of Health and Environment
Forbes Field, Building 730
Topeka, KS 66620
(913) 269-1607
Kentucky
Division of Waste Management
Natural Resources and Environmental Protection
Cabinet
18 Reilly Road
Frankfort, KY 40601
(502) 564-6716
Kentucky Partners
Room 312 Ernst Hall
University of Louisville
Speed Scientific School
Louisville, KY 40292
(502) 588-7260
64
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Louisiana
Department of Environmental Quality
Office of Solid and Hazardous Waste
P.O. Box 44307
Baton Rouge, LA 70804
(504) 342-1354
Maine
State Planning Office
184 State Street
Augusta, ME 04333
(207)289-3261
Maryland
Maryland Hazardous Waste Facilities Siting Board
60 West Street, Suite 200 A
Annapolis, MD 21401
(301) 974-3432
Massachusetts
Office of Technical Assistance
Executive Office of Environmental Affairs
100 Cambridge Street, Room 1904
Boston, MA 02202
(617) 727-3260
Source Reduction Program
Massachusetts Department of Environmental
Quality Engineering
1 Winter Street
Boston, MA 02108
(617)292-5982
Michigan
Resource Recovery Section
Department of Natural Resources
P.O. Box 30028
Lansing, MI 48909
(517)373-0540
Minnesota .
Minnesota Pollution Control Agency
Solid and Hazardous Waste Division
520 Lafayette Road
St. Paul, MN 55155
(612)296-6300
Minnesota Technical Assistance Program
1313 5th Street, S.E., Suite 2Q7
Minneapolis, MN 55414
(612) 627-4646
(800) 247-0015 (in Minnesota)
Mississippi
Waste Reduction & Minimization Program
Bureau of Pollution Control
Department of Environmental Quality
P.O. Box 10385
Jackson, MS 39289-0385
(601)961-5190
Missouri
State Environmental Improvement and Energy
Resources Agency
P.O. Box 744
Jefferson City, MO 65102
(314) 751-4919
Waste Management Program
Missouri Department of Natural Resources
Jefferson Building, 13th Floor
P.O. Box 176
Jefferson City, MO 65102
(314)751-3176
Nebraska
Land Quality Division
Nebraska Department of Environmental Control
Box 98922
State House Station
Lincoln, NE 68509-8922
(402)471-2186
Hazardous Waste Section
Nebraska Department of Environmental Control
P.O. Box 98922
Lincoln, NE 68509-8922
(402) 471-2186
New Jersey
New Jersey Hazardous Waste Facilities Siting
Commission <:.;.
Room 514
28 West State Street
Trenton, NJ 08625
(609) 292-1459 ;
(609) 292-1026
65
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Hazardous Waste Advisement Program
Bureau of Regulation and Classification
New Jersey Department of Environmental Protection
401 East State Street
Trenton, NJ 08625
(609) 292-8341
Risk Reduction Unit
Office of Science and Research
New Jersey Department of Environmental Protection
401 East State Street
Trenton, NJ 08625
(609)292-8341
New Mexico , ,
Economic Development Department
Bataan Memorial Building
State Capitol Complex
Santa Fe, NM 87503
(505) 827-6207
New York
New York Environmental Facilities Corporation
50 Wolf Road
Albany, NY 12205
(518) 457-4222
North Carolina
Pollution Prevention Pays Program
Department of Natural Resources and Community
Development
P.O. Box 27687
512 North Salisbury Street
Raleigh, NC 27611-7687
(919) 733-7015
Governor's Waste Management Board
P.O. Box 27687
325 North Salisbury Street
Raleigh, NC 27611-7687
(919) 733-9020
Technical Assistance Unit
Solid and Hazardous Waste Management Branch
North Carolina Department of Human Resources
P.O. Box 2091
306 North Wilmington Street
Raleigh, NC 27602
(919) 733-2178
North Dakota
North Dakota Economic Development Commission
Liberty Memorial Building
State Capitol Grounds
Bismarck, ND 58505
(701) 224-2810
Ohio
Division of Hazardous Waste Management
Division of Solid and Infectious Wjiiste Management
Ohio Environmental Protection Agency
P.O. Box 0149
1800 Watermark Drive
Columbus, OH 43266-0149
(614) 644-2917
Oklahoma
Industrial Waste Elimination Program
Oklahoma State Department of Health
P.O. Box 53551
Oklahoma City, OK 73152
(405)271-7353
- I ..
Oregon
Oregon Hazardous Waste Reduction Program
Department of Environmental Quality
811 Southwest Sixth Avenue
Portland, OR 97204, ,
(503) 229-5913
(800) 452-4011 (in Oregon)
Pennsylvania
Pennsylvania Technical Assistance Program
501 F. Orvis Keller Building
University Park, PA 16802 r
(814) 865-0427
Center of Hazardous Material Research
Subsidiary of the University of Pittsburgh Trust
320 William Pitt Way
Pittsburgh, PA 15238
(412) 826-5320
(800)334-2467 -
Puerto Rico
Government of Puerto Rico
Economic Development Administration
Box 2350
San Juan, PR 00936
(809) 758-4747
66
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Rhode Island
Hazardous Waste Reduction Section
Office of Environmental Management
83 Park Street
Providence, RI 02903
(401) 277-3434
(800) 253-2674 (in Rhode Island)
South Carolina
Center for Waste Minimization
Department of Health and Environmental Control
2600 Bull Street
Columbia, SC 29201
(803) 734-4715
South Dakota
Department of State Development
P.O. Box 6000
Pierre, SD 57501
(800) 843-8000
Tennessee
Center for Industrial Services
University of Tennessee
Building #401
226 Capitol Boulevard
Nashville, TN 37219-1804
(615)242-2456
Bureau of Environment
Tennessee Department of Health and Environment
150 9th Avenue North
Nashville, TN 37219-5404
(615) 741-3657
Tennessee Hazardous Waste Minimization Program
Tennessee Department of Economic and Community
Development
Division of Existing Industry Services
7th Floor, 320 6th Avenue, North
Nashville, TN 37219
(615) 741-1888
Texas
Texas Economic Development Authority
410 East Fifth Street
Austin, TX 78701
(512) 472-5059
Utah
Utah Division of Economic Development
6150 State Office Building
Salt Lake City, UT 84114
(801) 533-5325
Vermont
Economic Development Department
Pavilion Office Building
Montpelier, VT 05602
(802) 828-3221
Virginia
Office of Policy and Planning
Virginia Department of Waste Management
llth Floor, Monroe Building
101 North 14th Street
Richmond, VA 23219
(804) 225-2667
Washington
Hazardous Waste Section
Mail Stop PV-11
Washington Department of Ecology
Olympia,WA 98504-8711
(206)459-6322
West Virginia
Governor's Office of Economics and Community
Development
Building G, Room B-517
Capitol Complex
Charleston, WV 25305
(304) 348-2234
Wisconsin
Bureau of Solid Waste Management
Wisconsin Department of Natural Resources
P.O. Box 7921
101 South Webster Street
Madison, WI 53707
(608) 267-3763
Wyoming
Solid Waste Management Program
Wyoming Department of Environmental Quality
Herschler Building, 4th Floor, West Wing
122 West 25th Street
Cheyenne, WY 82002
(307) 777-7752
67
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Waste Exchanges
Alberta Waste Materials Exchange
Mr. William C. Kay
Alberta Research Council
P.O. Box 8330
Postal Station F
Edmonton, Alberta
CANADA T6H5X2
(403) 450-5408
British Columbia Waste Exchange
Ms. Judy Toth
2150 Maple Street
Vancouver, B.C.
CANADA V6J3T3
(604) 731-7222
California Waste Exchange
Mr. Robert McCormick
Department of Health Services
Toxic Substances Control Program
Alternative Technology Division
P.O. Box 942732
Sacramento, CA 94234-7320
(916) 324-1807
Canadian Chemical Exchange*
Mr. Philippe LaRoche
P.O. Box 1135
Ste-Adele, Quebec
CANADA JOR1LO
(514) 229-6511
Canadian Waste Materials Exchange
ORTECH International
Dr. Robert Laughlin
2395 Speakman Drive
Mississauga, Ontario
CANADA L5K1B3
(416) 822-41 ll(ExL 265)
FAX: (416)823-1446
Enstar Corporation*
Mr. J. T. Engster
P.O. Box 189
Latham, NY 12110
(518) 785-0470
Great Lakes Regional Waste Exchange
400 Ann Street, N.W., Suite 204
Grand Rapids, MI 49504
(616) 363-3262
Indiana Waste Exchange
Dr. Lynn A. Corson
Purdue University
School of Civil Engineering
Civil Engineering Building
West Lafayette, IN 47907
(317) 494-5036
Industrial Materials Exchange
Mr. Jerry Henderson
172 20th Avenue
Seattle, WA 98122
(206) 296-4633
FAX: (206)296-0188
Industrial Materials Exchange Service
Ms. Diane Shockey
P.O. Box 19276
Springfield, IL 62794-9276
(217) 782-0450
FAX: (217)524-4193
Industrial Waste Information Exchange
Mr. William E. Payne
New Jersey Chamber of Commerce
5 Commerce Street |
Newark, NJ 07102
(201) 623-7070
Manitoba Waste Exchange
Mr. James Ferguson
c/o Biomass Energy Institute, Inc.
1329 Niakwa Road i
Winnipeg, Manitoba
CANADA R2J3T4
(204) 257-3891
*For-Profit Waste Information Exchange
68
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Montana Industrial Waste Exchange
Mr. Don Ingles
Montana Chamber of Commerce
P.O. Box 1730
Helena, MT 59624
(406) 442-2405
New Hampshire Waste Exchange
Mr. Gary J. Olson
c/o NHRRA
P.O. Box 721
Concord, NH 03301
(603)224-6996
Northeast Industrial Waste Exchange, Inc.
Mr. Lewis Cutler
90 Presidential Plaza, Suite 122
Syracuse, NY 13202
(315) 422-6572
FAX: (315)422-9051
Ontario Waste Exchange
ORTECH International
Ms. Linda Varangu
2395 Speakman Drive
Mississauga, Ontario
CANADA L5K1B3
(416) 822-4111 (Ext 512)
FAX: (416) 823-1446
Pacific Materials Exchange
Mr. Bob Smee
South 3707 Godfrey Boulevard
Spokane, WA 99204
(509)623-4244
Peel Regional Waste Exchange
Mr. Glen Milbury
Regional Municipality of Peel
10 Peel Center Drive
Brampton, Ontario
CANADA L6T4B9
(416) 791-9400
RENEW
Ms. Hope Castillo
Texas Water Commission
P.O. Box 13087
Austin, TX 78711-3087
(512) 463-7773
FAX: (512)463-8317
San Francisco Waste Exchange
Ms. Portia Sinnott
2524 Benvenue #35
Berkeley, CA 94704
(415) 548-6659
Southeast Waste Exchange
Ms. Maxie L. May
Urban Institute
UNCC Station
Charlotte, NC 28223
(704) 547-2307
Southern Waste Information Exchange
Mr. Eugene B. Jones
P.O. Box 960
Tallahassee, FL 32302
(800) 441-SWJX (7949)
(904) 644-5516
FAX: (904)574-6704
Tennessee Waste Exchange
Ms. Patti Christian
226 Capital Boulevard, Suite 800
Nashville, TN 37202
(615) 256-5141
FAX: (615)256-6726
Wastelink, Division of Tencon, Inc.
Ms. Mary E. Malotke
140 Wooster Pike
Milford, OH 45150
(513) 248-0012
FAX: (513)248-1094.
U.S. EPA Regional Offices
Region 1 (VT, NH, ME, MA, CT, RI)
John F. Kennedy Federal Building
Boston, MA 02203
(617) 565-3715
Region 2 (NY, NJ, PR, VI)
26 Federal Plaza
New York, NY 10278
(212) 264-2525
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Region 3 (PA, DE, MD, WV, VA, DC)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-9800
Region 4 (KY, TN, NC, SC, GA, FL, AL, MS)
345 Courfland Street, N.E.
Atlanta, GA 30365
(404) 347-4727
Region 5 (WI, MN, MI, IL, IN, OH)
230 South Dearborn Street
Chicago, IL 60604
(312) 353-2000
Region 6 (NM, OK, AR, LA, TX)
1445 Ross Avenue
Dallas, TX 75202
(214) 655-6444
Region 7 ONE, KS, MO, IA)
756 Minnesota Avenue
Kansas City, KS 66101
(913) 236-2800
Region 8 (MT, ND, SD, WY, UT, CO)
999 18th Street
Denver, CO 80202-2405
(303)293-1603
Region 9 (CA, NV, AZ, HI, GU)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1305
Region 10 (AK, WA, OR, ID)
1200 Sixth Avenue
Seattle, WA 98101
(206)442-5810
Industry & Trade Associations
American Foundreymaen's Society (AFS)
505 State Street
Des Plaines, IL 60016-8399
(708) 824-0181
ASM International
Materials Park, OH 44073
(216) 338-5151
Ductile Iron Society
28938 Lorain Road
North Olmstead, OH 44070
(216) 734-8040
Investment Casting Institute
8350 North Central Expressway
Suite M-1110
Dallas, TX 75206-1602
(214) 368-8896
Metal Treating Institute
300 North Second Street, Suite 1
Jacksonville Beach, FL 32250
(904) 249-0448
Nonferrous Founder's Society
455 State Street, Suite 100
Des Plaines, IL 60016
(708)299-0950
North American Die Casting Association
2000 North Fifth Avenue
River Grove, EL 60171-1992
(708) 452-0700
Steel Founder's Society of America
Cast Metals Federation Building
455 State Street ''
Des Plaines, IL 60016
(708) 299-9160
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