United States
           Environmental Protection
             Office of Research and
             Washington DC 20460
September 1992
Guides to Pollution

Metal Casting and
Heat Treating Industry


                                            September 1992
       Guides to Pollution Prevention

The Metal Casting and Heat Treating Industry
        Risk Reduction Engineering Laboratory
     Center for Environmental Research Information
         Office of Research and Development
        U.S. Envirpnmental Protection Agency
                Cincinnati, OH 45268
                                          Printed on Recycled Paper

    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.           '

    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

    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

    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.                        \
    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.





1.   Introduction  	

     Overview of Waste Minimization  	
     Waste Minimization Opportunity Assessment	

2.   Metal Casting and Heat Treating Industry Profiles	

     Industry Description	
     Metal Casting Industry	
     Heat Treating Industry	

3.   Waste Minimization Options for Metal Casting, and Heat Treating Facilities

     Metal Casting Industry	
     Heat Treating Industry	

4.   Guidelines for Using the Waste Minimization Assessment Worksheets ....

     Metal Casting and Heat Treating Facility Assessments:
     Case Studies of Plants	

     Where to Get Help: Further Information on Pollution Prevention	










   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

   •   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

   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

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

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.


   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.


   '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

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;

     The Recognized Need to Minimize Waste

     • Get management commitment
     • Set overall assessment program goals
     ' Organize assessment program task force
           Assessment Organization &
             Commitment to Proceed

     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

        • Technical evaluation
        • Economic evaluation
        • Select options for implementation
             Final Report, Including
            Recommended Options


        • Justify projects and obtain funding
        p Installation (equipment)
        • Implementation (procedure)
        1 Evaluate performance
Repeat the
           Successfully Implemented
           Waste Minimization Projects
Figure 1.  The Waste Minimization Assessment Procedure

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.         ;


   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


   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.


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.,

USEPA.  1988.  Waste Minimization Opportunity As-
   sessment Manual.  U.S.  Environmental Protection
   Agency, Hazardous Waste Engineering  Research
   Laboratory, Cincinnati, EPA/625/7-88/003.

                                          SECTION 2
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.


   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
 Molding and Coremaking  Spent system sand
                        Sweepings, core butts
                        Dust and sludge
Dust and fumes
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)




Riser Cutoff
                                                      Initial Heat
                                                      Cleaning &
                   Final Heat
                                                              Inspection &
           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
   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.

   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,

   • 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

   • 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

   • 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

   •  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."


   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

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.


   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.


   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.

    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

    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

    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.


   Castings are  coated using plating solutions, molten
metal baths, alloys, powdered metals, volatilized metal
or metal salt, phosphate coatings, porcelain enamels,
and organic coatings.


   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

   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

   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

New Sand
& Binder

Raw Metal
                                                               & Finishing
 Note 1
   Mixing &
Molding &
                                            & Milling
                                             Note 2
 Waste Sand
                                         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

   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

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.


   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
 Heat Treating

 Case Hardening


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

   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

   •  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
   NaCN + CO2 <-> NaNCO + CO

             Table 3.  Operating Composition of Liquid Carburizing Baths
                                                                 Composition of Bath, %
    Light Case,
 Low Temperature
845 to 900°C (1550
    to 1650°F)
   Deep Case,
 High Temperature
    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
20 to 40
30 max
Oto 5
1.0 max
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

                                                        (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
                     Table 4.  Compositions and Properties of Sodium
                               Cyanide Mixtures for Cyaniding Baths

oonsmuent or
Composition, %
Sodium cyanide
Sodium carbonate
Sodium chloride
Melting point, °C (°F)

Specific gravity
At 25°C (75°F)
At 860°C (1580°F)








                     (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.

Reactions that  influence cyanate content proceed as

   NaNCO + C -> NaCN + CO                   (4)

and either

   4 NaNCO + 2 O2 -> 2 Na2CO3 + 2 CO + 4 N  (5)


   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 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

   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

remove either salt or oil that remains after the quench-
ing process.                                  '     ,


   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.


   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.


   Cyanide salts on the part  contaminate the quench-
ing bath, rendering the bath  a hazardous waste when

   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

   •  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

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-

   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).


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.

                                         SECTION 3

   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.


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.


   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

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.

   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


   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

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.


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

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.


   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

   •  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

   •  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


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

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

   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.

                                             Reagents ——
                           Metal Product
                         Weight = 0.5-1.0%
EP Toxicity
Feed Sand
Weight = 100%

• •
1 1
EP Toxicity
< 0.1 0-30 ppmPb
Clean Sand
Weight = 98-99%
    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

   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

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).
   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

   •   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

   •   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

   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.
   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


   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

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

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

   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

      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-

      — 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

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

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.

  •  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

  •  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

  •  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

  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

  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.).


    Quenching media used in  heat  treating processes
 become  hazardous  waste  when  exposed  to  metal

 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

 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.

 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

   •  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

   •  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


   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

   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

Plant 	 Waste Minimization Assessment Prepared by
Checked By
Date- Proj. No. Sheet of Page of


Waste Source: Casting
Baghouse dust .
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
Alkaline wastes
Acid wastes
Waste water
Air emissions
Waste Source: Surface Treatment and Plating
Spent bath solutions
Filter waste
Rinse water
Spills and leaks
Solid waste
Air emissions
Waste Source: Other Processes
Leftover raw materials
Other process wastes
Pollution control residues
Waste management residues




 Waste Minimization Assessment
Proj. No..
Prepared by	
Checked By	_,
Sheet	of	Page
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?

Plant wacto Mjnjm
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Page of


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
Done Y/N?

Rationale/Remarks on Option


Waste Minimization Assessment
Proj. No.
Prepared by _
Checked By _
Sheet	of
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: 	

                                   Waste Minimization Assessment
Proj. No.
Prepared by	
Checked By	
Sheet	of	Page
                                   OPTION GENERATION:
                              HEAT TREATING OPERATIONS
 Meeting format (e.g., brainstorming, nominal group technique)
 Meeting Coordinator	
 Meeting Participants	
      Suggested Waste Minimization Options
               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

  Waste Minimization Assessment
 Proj. No.
Prepared by _
Checked By _
Sheet	of
    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	

                                 Waste Minimization Assessment
  Proj. No.
Prepared by _
Checked By _
Sheet	of
    Process Techniques:
        Spray Chamber
        Air-sparged Bath
        Agitated Bath
       Type of Aqueous Cleaner
                       Rag Wiping
     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:

         Waste Minimization Assessment
        Proj. No.
                     Prepared by _

                     Checked By _

                     Sheet	of
             AND STRIPPING
         Size of
        Rinse Bath
or Still Rinse
Are spray rinse techniques used within the plant?
                                                          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:


Waste Minimization t
Proj. No.
\ssessment Prei
jare'd by
eked By
et of Page of


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
Use Vapor Degreasers
Cover Immersion Tanks
Install Drainboards
Employ Material Substitution
Aqueous Cleaners
Remove Sludge
Use Tank Lids
Use Water-Based Binders
Use Liquid Spray Abrasives
Preclean Workpieces

B. Recycling Techniques
Filter Solvents
Distill Solvents
Reuse Blasting Media
Done Y/N?

Rationale/Remarks on Option


  Waste Minimization Assessment
 Proj. No..
Prepared by _
Checked By _
Sheet	of
Complete a worksheet for each process tank
Description of tank function: 	
Identification  number:	
Composition of process solution:
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?

Plant wacto Minjm
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Page of

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
Rinse System Design
Incorporate Still Rinse Design
Employ Counter-Current Rinsing
Assure Efficient Drainage
Use No-Rinse Coating
Product Substitution
Substitute Cadmium Plating Alternatives
Substitute Chromium Plating Alternatives
Substitute Cyanide Bath Alternatives
Use Immiscible Rinse

B. Recycling Techniques
Recycle Process Baths
Recycle Rinsewater
Done Y/N?

Rationale/Remarks on Option


          Waste Minimization Assessment
         Proj. No.
                    Prepared by	

                    Checked By	

                    Sheet	of	Page.
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?

                                              _Note:  If so, they must be managed as hazardous waste.
Type of Waste
Annual Amount
Potential source reduction and recycling opportunities:
Annual Cost of

Plant WastA Minim
Date Proj. No.
ization Assessmen
t Prepared by
Checked By
Sheet of Paqe of


Meeting format (e.g., brainstorming, nominal group technique)
Meeting Coordinator

Meeting Participants

Suggested Waste Minimization Options
A. Source Reduction Techniques

B. Recycling Techniques

Done Y/N?

Rationale/Remarks on Option


                                        Appendix A
                            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.

   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

 Foundry Waste Streams

   Hazardous waste streams from foundry  operations

   •  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


   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

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 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.


    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

   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


    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.


   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.


   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

   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.


   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  system—a "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.


   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

   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

   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


   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

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.


   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

   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,

   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  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


   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


   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


   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

   •  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

    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.


   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 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

   •  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 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


   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.

   •  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

     —  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

   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.


   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.

   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.


   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

   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.


   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

the Ni-resist furnaces is disposed of as  nonhazardous

   Wastes  generated in  cupola melting  operations
   •  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

   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.


   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

   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

   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
   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
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
   •  Off-site recycling to a smelter of lead-containing
      wastes. The smelter would pick up the material
      for the cost of $250 per ton.

   •  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

 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.

   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

   •  The  core  oven  gases  are  combusted  in  an

   •  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 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.


  No hazardous waste  is generated in the mold mak-
ing  operation.  Foundry spent sand is disposed of off
site as nonhazardous waste.


  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.


  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.


   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.

                                            Appendix B
                                 WHERE TO GET HELP:
   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

   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.
 Waste Minimization Opportunity Assessment Manual.

 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-

              Report to Congress:  Waste Minimization, Vols. I and
              II.  EPA/530-SW-86-033 and -034 (Washington, D.C.:
              U.S. EPA, 1986).***

              Waste Minimization—Issues 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.

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.

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:
 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-

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
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

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

Alaska Health Project
Waste Reduction Assistance Program
431 West Seventh Avenue, Suite 101
Anchorage, AK 99501
(907) 276-2864

Arizona Department of Economic Planning and
1645 West Jefferson Street
Phoenix, AZ 85007

Arkansas Industrial Development Commission
One State  Capitol  Mall
Little Rock, AR 72201
(501) 371-1370

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

Division of Commerce and Development Commission
500 State  Centennial Building
Denver, CO 80203
(303) 866-2205

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

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

Waste Reduction Assistance Program
Florida Department of Environmental Regulation
2600 Blair Stone Road
Tallahassee, FL  32399-2400
(904) 488-0300

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

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

Hazardous Materials Bureau
450 West State Street, 3rd Floor
Boise, ID  83720
(208) 334-5879

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

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
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

Bureau of Waste Management
Department of Health and Environment
Forbes Field, Building 730
Topeka, KS  66620
(913) 269-1607

Division of Waste Management
Natural Resources and Environmental Protection
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

Department of Environmental Quality
Office of Solid and Hazardous Waste
P.O. Box 44307
Baton Rouge, LA  70804
(504) 342-1354

State Planning Office
184 State Street
Augusta, ME 04333

Maryland Hazardous Waste Facilities Siting Board
60 West Street, Suite 200 A
Annapolis, MD  21401
(301) 974-3432

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

Resource Recovery Section
Department of Natural Resources
P.O. Box 30028
Lansing, MI 48909

Minnesota                    .
Minnesota Pollution Control Agency
Solid and Hazardous Waste Division
520 Lafayette Road
St. Paul, MN 55155
Minnesota Technical Assistance Program
1313 5th Street, S.E., Suite 2Q7
Minneapolis, MN  55414
(612) 627-4646
(800) 247-0015 (in Minnesota)

Waste Reduction & Minimization Program
Bureau of Pollution Control
Department of Environmental Quality
P.O. Box 10385
Jackson, MS  39289-0385

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

Land Quality Division
Nebraska Department of Environmental Control
Box 98922
State House Station
Lincoln, NE 68509-8922

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

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

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
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

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

Industrial Waste Elimination Program
Oklahoma State Department of Health
P.O. Box 53551
Oklahoma City, OK  73152
                             - I        ..
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 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

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

Center for Industrial Services
University of Tennessee
Building #401
226 Capitol Boulevard
Nashville, TN 37219-1804

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
Division of Existing Industry Services
7th Floor, 320 6th Avenue, North
Nashville, TN 37219
(615) 741-1888

Texas Economic Development Authority
410 East Fifth Street
Austin, TX  78701
(512) 472-5059
Utah Division of Economic Development
6150 State Office Building
Salt Lake City, UT  84114
(801) 533-5325

Economic Development Department
Pavilion Office Building
Montpelier, VT  05602
(802) 828-3221

Office of Policy and Planning
Virginia Department of Waste Management
llth Floor, Monroe Building
101 North 14th Street
Richmond, VA  23219
(804) 225-2667

Hazardous Waste Section
Mail Stop PV-11
Washington Department of Ecology
Olympia,WA  98504-8711

West Virginia
Governor's Office of Economics and Community
Building G, Room B-517
Capitol Complex
Charleston, WV 25305
(304) 348-2234

Bureau of Solid Waste Management
Wisconsin Department of Natural Resources
P.O. Box 7921
101 South Webster Street
Madison, WI  53707
(608) 267-3763

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

Waste Exchanges

Alberta Waste Materials Exchange
Mr. William C. Kay
Alberta Research Council
P.O. Box 8330
Postal Station F
Edmonton, Alberta
(403) 450-5408

British Columbia Waste Exchange
Ms. Judy Toth
2150 Maple Street
Vancouver, B.C.
(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
(514) 229-6511

Canadian Waste Materials Exchange
ORTECH International
Dr. Robert Laughlin
2395 Speakman Drive
Mississauga, Ontario
(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
(204) 257-3891
 *For-Profit Waste Information Exchange

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
P.O. Box 721
Concord, NH 03301

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
(416) 822-4111 (Ext 512)
FAX:  (416) 823-1446

Pacific Materials Exchange
Mr. Bob Smee
South 3707 Godfrey Boulevard
Spokane, WA 99204

Peel Regional Waste Exchange
Mr. Glen Milbury
Regional Municipality of Peel
10 Peel Center Drive
Brampton, Ontario
(416) 791-9400

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

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

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
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

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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