'I LINGUAL MANUAL
SOLUTION PREVENTION
                        Waste
                        Minimization
                        for the Metal
                        Developed by
                        U.S^ EPA/SEDESOL
                        Pollution Prevention
                        Workgroup


                        May 1993

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                      SECTION I
                      Introduction
    Sfc^

Jf'Kfe"". a

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CASE STUDIES FOR THE METAL      ,

FINISHING INDUSTRY

    This appendix provides four case studies of waste minimization efforts in the metal
    finishing industry. The case studies provide examples that coyer the range of
    pollution prevention options existing in this industry. Recognizing that waste
    disposal costs differ between Mexico and the United States (from where these
    case studies originate), the case studies provide examples of potential savings.
    Moreover, health and other benefits often result when a pollution prevention
    .program is implemented.          .     '      "  . ,

    The four case studies in this, appendix were derived from diverse spurces, thus the
    material contained in each case study may differ slightly from the other three
    studies presented in this appendix. Numerous case studies, other than those
    presented in this appendix, have been written in the United States. The reference
    list in the back of this manual lists sources for additional case studies.


  CASE STUDY NO. 1:
  MANUFACTURER OF COMPONENTS FOR AUTOMOBILE
  AIR CONDITIONERS1

    INTRODUCTION

    Case Study No. 1 presents waste minimization efforts at a plant that manufactures
    three distinct product components for automobile air conditioners: (1) charged air
    coolers, (2) round tube plate fin (RTPF) condensers, and (3) air conditioning tubes.

    WASTE GENERATION ACTIVITIES

    Charged Air Coolers

    When manufacturing charged air coolers, sand^cast aluminum tanks are cleaned
    in an aqueous alkaline bath at 160 degrees Fahrenheit (°F), rinsed in successive
    stages, air dried, and inspected. Air and turbulator fins! headers, and side sheets
    are fabricated, hand-assembled into air "coolers, brazed, and painted. The wastes
    generated by these processes include:     .       ,

       • Lubricating oil, generated (1) wheh.coil stock is made into air fins, turbulator
         fins, headers, and side sheets and (2) when extruded aluminum tubes are
         cut to length and debarred       '-N:

  ••••'"  • Scrap metal, generated when headers and side sheets are made from-
        ; aluminum coil stock                             -    ;        '

       • Spent solvent (trichloroethane, perchldrethytene), generated during
         degreasing operations    -                .     ..•••;','.

       • Paint booth waste containing sblvent^and paint, generated during paint gun
         cleaning; water, generated when water rjuns off the paint booth's water
         curtain; waste paint solids; and overspray\
1 Taken from, "Pollution Prevention Case Stuates.Compendium,' U.S. Environmental Protection Agency, Office of
 Research and Development, Washington, D.C. 20460, EPA/600/R-046, April 1992   •


CASE STUDIES.        '   •               .      .   .

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RTPF Condensers

When manufacturing RTPF condensers, steel headers, aluminum hairpins, and
aluminum'coil stock (for fins) are fashioned into parts, degreased using,
perchlorethylene, dried, assembled into the condenser body, brazed, flushed with
hot water, leak tested, oven dried, and dip painted. These manufacturing
operations generate wastes similar to those generated when charged air coolers
are manufactured.

Air Conditioning Tubes

When manufacturing air conditioning tubes, aluminum coil tubing is cut to length,
formed, and straightened. About 39 percent of the product is degreased using
trichloroethane. The other 61 percent is welded, pierced, and welded again before
being degreased, dried, and leak tested. Cutting oils and solvent wastes are
generated by these processes.

WASTE MANAGEMENT ACTIVITIES

This plant generates several different types of waste annually. Approximately 40
barrels of spent oil are disposed of off site. Twenty-five barrels of still bottoms (one
third of which is trichtoroethene. the remainder of which is perchlorethene) are
disposed of off site. Approximately 1.4 million gallons of process wastewater is     ,
treated at the facility and emptied into the sewer. Approximately 250,000 pounds
of aluminum and steel scrap is sold as refuse. Twenty barrels of paint sludge are
disposed of as hazardous waste.

The plant presently has a solvent distillation unit used to recover spent.solventand
a secondary still used to recover solvent from the bottom of the first still. The plant
has virtually eliminated sludge from its wastewater treatment system. The plant
sells scrap aluminum  and steel generated on site for $146,500 per year.

WA STE MINIMIZATION OPPORTUNITIES

 By replacing the chlorinated hydrocarbon solvents wtth'degreasers that can be_
 directly discharged to sewers, waste disposal costs would be reduced by $6,007
 per year and raw material cost savings would amount to $62,640 per year. The
 payback period for the $20.700 implementation costs would be about 4 months
 Note that of the 11,000 plus gallons of solvent used each year, 92 to 98 percent is
 lost to evaporation.
 By not feeding water to idle rinse tanks arid by converting thesetanks to a     _  _
 cbunterftow rinse system, $33,235 would be saved each year. The payback penod
 £*»$a*a^Sptementattoncost would be about 1 month. By converting present
  painting operations to electrostatic powder coating, waste solvents and other
 •wasteS irSuding water, paint solids, used plastic liners, and spray tmtti coabng.
  would bVreduced or eliminated. Each year, waste d.sposal costss wouldI be
  reduced $5 869 and raw material cost savings would amount to $22,885. Tne
  paybackperiod forthe $100,640 implementation cost would be 3.5 years.

  By fabricating lightweight plastic tops and using them to cove r the ^greasing units
  when not in use, solvent evaporation would reduce raw material costs by' $26^75
  per year. The payback period for the $3,600 implementation cost would be about 1
   month.                                               ,
                                 WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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  CASE STUDY NO. 2:
  METAL RECOVERY DRAGOUT REDUCTION2

    Case Study No. 2 presents waste minimization efforts at an electroplating facility;
    These efforts were undertaken as part of the Minnesota Waste Management
    Board's MnTAP program, which is supported by a grant to the School of Public
    Health, Division of Environmental and Occupational Health, at the University of
    Minnesota.!

    INTRODUCTION

    New Dimension Plating is an electroplating facility that employs about 40 people in
    Hutchinson, Minnesota. While the plant plates a variety of metals, including gold
    and brass, most of the plating activities at the plant involve applying chromium to
  ,  objects that have been previously coated with copper and nickel. Hazardous
    waste is generated by plating tank dragout. This waste contained a significant
    amount of chromium and smaller quantities of nickel, chlorine, and copper.

    WASTE GENERATION ACTIVITIES

    The plant's original electroplating system used a stagnant rinse tank and three
    countercurrent rinses to remove excess chromium solution from newly plated
    parts. The initial stagnant rinse tank received a large portion of the chromium. The
    contents of this rinse water were then gradually returned to the plating tank to
    replace evaporated solution. Wastewater frorri the first, most cpncentrated, rinse in
    the countercurrent rinse series drained to the plant's pretreatment system where
    chromium was removed during sludge production (see Rgurel).

    WASTE MTNTMT7ATION OPPORTUNITIES

    New Dimension Plating redesigned its electroplating system and hazardous waste
    pretreatment system to meet the following goals:

      •  Maintain high quality plating

      •  Reduce the amount of chromium dragged out of the plating bath

      •  Reuse chromiumlin the plating bath -;                         ^

      •  Reduce sludge'production

      •  Reduce the  use of treatment chemicals

    To reduce the amount of chromium dragout, New Dimension Plating decided to
    install a drip bar in a spray rinse tank. New Dimension built the spray rinse tank
   . and drip bars in the original system's stagnant rinse tank. The new system allows
    the company to reduce dragout by providing longer drip time, thus avoiding the
    possibility of staining. By adjusting the size of the nozzles and the length of
    spraying time, the amount of rinse water solution can also be controlled. By
    increasing evaporation in the chromium tank, all of this solution can be returned to
    the plating tank on a  daily basis, thereby reducing the amount of dragout that
    continues through the rinse system (see Figure 2).
2 Taken Irom, 'MnTAP,' Minnesota Technical Assistance Program, date unknown


CASE STUDIES  •''•..'             ', ; '"-•

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                                Figure 1 - Original System
Processing and
 Undercoating
 Plating Bath
     Wastewater
      from rinse
 Chromium
Plating Bath
Co
untercurrent
Rinses
^ 	
                   i   Return to
                   i  plating bath
                   ;   to replace
                   :  evaporation
                                                           Wastewater from most
                                                             concentrated rinse
                                          I
                                                              Treatment with
                                                              metabisulphate
                                                                   i
                               Original Pretreatment Plant
                        (Sodium Hydroxide + Fitter Press + Sludge Drier)
 New Dimension Plating was meeting current regulations for wastewater discharge, but the
 operation of the system was very expensive. The company wanted to reduce chromium waste and
 cut treatment chemical costs, but maintain a high level of plating quality.
                   The approximate cost of the new equipment is as follows:
                        Evaporators
                        Pumps
                        Spray nozzles, racks
                        PPS2 Purifier
                        Installation
                        Total Cost
                           $1,000
                           $1,000

                              $50
                             $350

                             $500
                           $2,900
                   The operating cost of the new system is minimal, with no added costs for utilities
                   or supplies. Additional labor consists of approximately 1 hour every 2 weeks.

                   The first of the three original countercurrent rinse tanks was converted to a
                   stagnant rinse tank, and the last two were combined into one large continuous
                   'rinsetank.

                   New Dimension built evaporators to reduce the volume of water in the plaiting tank.
                   The stagnant rinse tank was built to allow all of the spray rinse solution and some
                   of the stagnant rinse water to be returned to the tank each day.

                    An electropurification module was installed directly into the plating bath to remove
                    contaminants from the returned dragout solution without interrupting the plating
                    process. New Dimension Plating chose the Model PPS2 porous pot chrome
                    solution purifier, manufactured by Hard Chrome Plating Consultants of Cleveland,
                    Ohio. The company is completely satisfied with how this  unit functions and felt that
                    other manufacturers could obtain similar results with this type of unit.
                                                    WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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Figure 2 - New System
• . . r . •. --''-'''-.'" . ' ' •
--''•• ' • " : ••' - ' ' '••-"•.

/* N
Processing and
Undercoating
Plating Bath
V J
Wastewatei
from rinses
r*
V
r \
1 Evaporator I
1 J
r \
^ Chromium i
.^" Plating Bath ~
> '<•
r Electro- A
L purification I
^ Module , J

• , - -'. ' ' •
Spray c. * '
fc, Rinse ^ Stagnant . chromium
w Tank with ~"^ Tank ^ Plating Bath
Qa/*l^e ^^ ' ' •
• . i . - . .
_._ _. — , , . _ i
Return to \ • Partial return to ...
plating bath :' i plating bath to
toreplaca j [ replace Wastewater from most
avaporaaoh i' evaporation concentrated rinse
Treatment with
metabisulphate
Original Pretraatment Plant '
(Soctum Hydroxide + FiK9rPi9a3 + Sludg9Driot)
•: "' ': " • . ' J
As a result of the new system, the amount of chromium dragout fed into the stagnant rinse tank
was reduced from 7 pounds to 1 pound per day.
  RESULTS AND DISCUSSION

  Change:

  installation of the spray rinse and drip
  bar in the existing stagnant rinse tank.
  Conversation of counter-current rinses
  into one stagnant rinse and one large
  continuous rinses'^    '
  Installation of the electro-purification unit
  (the Mode IPPS porous potchrome
  solution purifier) In the chromium plating
  tank.
Results;

This initial rinse following the
chromium plating reduces dragout in
the system because all of the rinse
water is returned to the plating tank.

The new rinse system reduces water
flow from 1.2 gallons per minute (gpm)
to 1.0 gpm. The large rinse tank
makes rinsing of the large parts more
efficient.

The unit allows reuse of the dragged
out chromium by removing
contaminants from the rinse water
retume
CASE STUDIES

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  By using a spray rinse system with a drip bar following the chromium plating .bath,
  New Dimension Plating has reduced dragout from 7 pounds to 1 pound daily.
  When combined with in-tank electropurification of metal contaminants, this
  reduction reduced sludge production and saved an estimated $7,000 associated
  with the purchase of chromium and treatment chemicals. New Dimension has
  been quite satisfied with the results of the new system.


CASE STUDY NO. 3: WASTE MINIMIZATION ASSESSMENT
FOR A MANUFACTURER OF SHEET METAL CABINETS AND
PRECISION METAL FARTS3

  INTRODUCTION
  Case Study No 3 presents waste minimization efforts at a plant that manufactures
  sheet metal cabinets and precision metal parts. Approximately 1.15 million parts
 . are produced annually by 140 employees who operate the plant 2,210 hours per
  year  To make the cabinets, sheet metal is cut to size, bent, welded, and polished.
  The surface of the metal parts is then treated and painted. The machined parts are
  produced from bar stock that is cut, drilled, milled, and ground as needed. Most of
  the waste at the facility is generated by the chromate conversion and iron
  phosphate coating processes. These processes are used to prepare the parts for
  painting.                                                  .

  WASTE GENFtt ATTON ACTIVITIES

  When making the metal cabinets, sheets of aluminum and steel are cut to the
   proper size and shape, and holes are punched into the metal. The metal is then
   bent and welded together as needed. Rough edges and surfaces are polished
   using power senders and buffers. Scrap metal is shipped to a scrap metal dealer
   for recycling. Spent cutting fluid and waste hydraulic oil are combined and shipped
   off site for recycling or incineration.

   Before painting, the surface of the metal parts is treated to improve paint bonding
   and provide corrosion protection. Aluminum parts receive a chromate conversion
   coating, and steel parts receive an iron phosphate coating.

   During treatment, aluminum  parts are dipped in a caustic cleaning solution and
   rinsed in a continuous-flow tap-water rinse. The parts-are then dipped in a third
   tank containing a desmut solution and rinsed again in another continuous-flow tap-
   water rinse. Next, the parts are placed in a chromic acid-based chromate
   conversion solution, rinsed in another continuous-flow tap-water rinse, and finally
   placed in a tank containing a heated dead-rinse of tap water. The caustic cleaner,
   desmut, and first rinse tanks are dumped monthly; the chromic acid tank is
   dumped every 3 to 4 years;  and the remaining solutions are dumped every 5
    months. In addition, sludge accumulates in the caustic cleaner tank, which is
    cleaned monthly.
    When coating steel parts with iron phosphate, the parts are dipped in ^caustic
    cleaning tank and then rinsed with a continuous-flow tap-water nnse. The parts; are
    then dipped in a tank that contains an iron phosphating solution and subjected to
 .   another continuous-flow tap-water rinse. The parts are finally dipped in a
    deoxidizing solution. All of these baths are dumped and replenished on a monthly
  '  basis. Combined wastewaters from the iron phosphate and chromate conversion

> Taken Iron, -Znvinnmentol Research Brief.' U.S. Environmental Protection Agency. Research and Developrrsnt. RisK
 ReducttonEngineering Laboratocy. Cincinnati. OH 45268. EPA/600/S-92/019. May 1992
     .                               WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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   lines drain to an overflow tank. These wastewaters are then drained to the sewer
   as industrial wastewater. Typically, the wastewaters are not pretreated prior to
   discharge because the wastewater meets discharge limits set by the publicly
   owned treatment works (POTW). Sludge accumulates in the caustic cleaner and
   iron phosphate tanks and is disposed of monthly.

   Solvent-based paint is applied to metal parts in dry paint booths. Waste paint,
   generated when the paint mixture becomes too thick, is shipped to a hazardous
   waste treatment, storage, or disposal facility (TSDF). Spent paint thinner is also
   shipped off site. Painted parts are dried and cured in ovens. The plant uses
   powder-based paint coatings  on a few parts. The type of paint used is dictated by
   the customer's requirements..

   When producing machined parts, bar stock is cut, drilled, milled, and ground as
   needed. Finished parts are assembled (if required) and shipped to customers.
   Mejal scrap is shipped to a scrap metal dealer for recycling. Spent cutting fluid and
   waste hydraulic oil are combined with similar wastes and shipped off site for
   recycling or incineration.

   WASTE MANAGEMENT ACTIVITIES

   This plant takes the following  steps to manage its wastes:
                                          -,/           /               - •   _
      • Scrap metal is segregated on site and sold to a recycler .

      • To contain spills, all reagent tanks in the phosphating and chromating lines
        are located in a large pit with a central drain.                           -

      • Drain boards are used between surface treatment tanks to reduce dragout.

      • Reagent solutions in the surface treatment lines are agitated with air to
        increase their effectiveness."                 .    -  ,
      • Dry paint booths are used to paint metal parts, thus avoiding the aqueous
        paint-laden wastes that are generated by wet paint booths.

      • A small powder coating unit is used to paint some products, thus avoiding
        the use of solvent-based paints.

      • Tank dumps are coordinated to achieve neutralization so  that the effluents
         discharged to the POTW  meet wastewater requirements.

    WASTE \nNIMIZATTONOProRTUNITIES

    Table 1 shows the opportunities for waste minimization at the facHity. The present
    practices, recommended actions, and waste reductions and their associated
    savings are aiso given in Table 1. The quantities of hazardous waste currently
    generated by the plant and possible waste reduction depend on the plant's
    production level. Allvalues should be considered in this context.

    It should be noted that, in most cases, the economic savings associated with
    waste minimization opportunities result from the need for less raw material and
    from reduced present and future costs associated with the treatment and disposal
    of hazardous waste. Other savings that are not^quantifiable include future costs
    related to changing emissions standards as well as costs associated with liability
    and employee health. It should also be  noted that the savings  given for each
    opportunity reflect the savings achievable when independently implementing each
    waste minimization opportunity; they do not reflect the duplicate savings that
    would result when the opportunities are implemented as a package.
CASE STUDIES

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                      In addition to the opportunities recommended and analyzed in Table 1, several
                      additional measures are presented below. These measures were not analyzed
                      completely because of insufficient data, implementation difficulty, or a projected
                      lengthy, payback. Since one or more of these approaches to waste reduction may
                      become more attractive over time, they were brought to the plant's attention for
                      future consideration.

                        • Install filtration units for the iron phosphating and caustic cleaner solutions to
                          increase solution life.

                        • Use deionized water to make-up and maintain the caustic cleaner and iron
                         , phosphating solutions, thereby reducing sludge formation.

                        • Substitute nonchromate conversion coating for conversion coating currently
                          used on aluminum parts.

                        • Increase drainage times over the tanks in the iron phosphating and chromate
                          conversion lines in order to reduce dragout.

                        • Segregate and recycle waste oil from the spent cutting fluid.

                        • Implement a preventive maintenance program in the machine shop to reduce
                          the quantities of spent cutting fluid and waste oil.
                   CASE STUDY NO. 4: WASTE MINIMIZATION ASSESSMENT
                   FOR A MANUFACTURER OF METAL-PLATED DISPLAY
                   RACKS4

                     INTRODUCTION

                     Case Study No. 4 discusses a plant that manufactures metal-plated display racks.
                     The plant's 200 employees process approximately 10 million pounds of metal
                     annually and operate the plant 4,160 hours per year. During this process, steel
                     wire, tubing, and sheets undergo machining operations, and the resulting parts are
                     nickel and brass-plated, nickel-plated, zinc-plated, nickel and chrome-plated, or
                     painted. The various finished parts are then assembled into display racks. The
                     majority of waste at the facility is generated by the plating lines.

                     WASTE GENERATION ACTIVITIES

                     The raw materials used to make the display racks include steel wire, tubing; and
                     sheets; nickel, zinc, and brass plating anodes; cleaning agents and plating solution
                     chemicals; and powder and liquid paints. Approximately 40 percent of the finished
                     products are nickel and brass-plated, 26 percent are nickel-plated, 24 percent are
                     zinc-plated, and 10 percent are nickel and chrome-plated.

                     The steel wire, tubing, and sheets undergo stamping, bending, forming, shaping,
                     welding, and riveting. The partsto be plated are then sent through one of the three
                     following plating lines. Other parts are sent to the paint line, which is also
                     descrfced below.         -~v
                                            '"  \
                 4Taken from. 'EnvtmnmrntalRosMKh B/teC U.S. Environmental Protection Agertey, Office of Research and
                  Development. RWc Reduction Engineering Ltboratoiy, Cincinnati. OH, EPA/600/S-92/021. May 1991


8                                               .     WASTE MINIMIZATION IN THE METAL FINISHING,INDUSTRY

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                                   /       Table!              A-
                        Waste Minimization Recommendations
Solvent-based paints are used to
coat the majority of this plant's
products. Waste paint, paint
sludge, and spent thinner are
disposed of offsite.
 A solvent recovery unit in the
 plant currently is not operational
 because of oil and water leaks.
 Cutting fluid is used until it
 becomes malodorous or until its
 viscosity and lubricity are
 unacceptable. Average fluid
 lifetime is about 3 months.
 Replace solvent-based painting
'with powder-based painting for a
 portion of the plants products.
 Cost savings will result from
 reduced disposal costs and
 reduced raw material costs.
 Installation of a batch spray booth
 for powder coating will be
 required.
                                 Replace solvent-based painting
                                 with water-based painting for a '
                                 portion of the plant's products (a
                                 separate portion from previous \
                                 WMO).  Cost savings will result
                                 from reduced disposal costs and
                                 reduced raw materials costs. This
                                 change requires the purchase of
                                 new paint application equipment
                                 and may require increased curing
                                 times.
Waste reduction = 72 gallons per
year (gal/yr) (waste paint and
paint sludge) + 66 gal/yr (spent
thinner); Waste management
cost savings = $740 per year;
Net raw material cost savings =
$14,230 per year; Total cost
savings = $14,970 per year;
implementation  cost = $20,600;
Simple payback = 1.4 years
                                 Waste reduction = 72 gal/yr
                                 (waste paint and paint sludge) +
                                 66 gal/yr (spent thinner); Waste
                                 management cost savings =
                                 $740 per year; Net raw material
                                 cost savings = $10,930 per year;
                                 Total cost savings « $11,670 per
                                 year; Implementation cost =
                                 $2,500; Simple payback = 0.2
                                 year
Overhaul the solvent recovery unit
to permit reuse of spent paint
thinner. Cost savings will result
from reduced disposal costs and
reduced purchases of thinner.
 Institute a program to recycle the
 cutting fluid onsite. Fluid should
 be filtered periodically to remove
 metal chips and particulate matter,
 thereby extending the life of the
 cutting fluid. In addition, the spent
 cutting fluid can be treated wffli
 acid to reduce (he volume of
 wastes that must be shipped
 offsite. The addition of acid will
 cause a phase separation;: the
 aqueous phase can be neutralized
 arid sewered and the organic
 phase should be disposed of
 offsite.
 Rinse water rates set by operators  Install a flow reducer and flow
 exceed flow rates required by the   meter In the.water supply line
 rinses in the chromata conversion
 and phosphating lines, £   '
 upstream of the rinses in the
 cnromato conversion and iron
 phosphating lines, thus reducing
 the quantity of water purchased
 and sewered
Waste reduction - 660 gal/yr;
Waste managementoost-
savings « $3,890 per year;
Net raw material cost sayings »
$1,780 per year; Operating cost
of recovery unit = $430 per year;
Net cost savings = $5,240 per
yean Implementation cost =
$2,500; Simple payback = 2.1
years

Waste reduction = 425 gal/yr;
Waste management cost
savings » $2,920 per year;
Net raw material cost savings =
$570 per year; Operating cost'of
filtration unit = $370
per year; Total cost savings =
$3,120 per year;  Implementation
cost * $7,050; Simple payback a
2.3 years
Waste reduction - 331',500 gal/
yn Waste management cost
savings'« $1,000 per year; Net
raw material cost savings - $510
per year; Total cost savings »
$610 per year;  Implementation
cost - $100; Simple payback *
0.2 year   '         .     '

CASE STUDIES

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BARREL PLATING LINE                                     *

Small fabricated parts are cleaned prior to plating to remove residual oils and
qrease by using either a vibrating cleaning unit or a rotating abrasive tub. The
vibrating tub cleans parts by vibrating them in a chemical solution. Spent cleaning
solution and rinse water are sent to the plant's wastewater treatment facility. In the
rotating abrasive tub, the parts and abrasive pellets are placed in small rotating
tubes. Spent abrasive pellets are disposed of in a landfill.

The cleaned parts are placed in hollow barrels that are attached to an overhead
conveyor system. The barrels, which have holes along the length of their surfaces,  -
are then slowly rotated while submerged for a specified amount of time in the
plating line's various tanks.

 Each batch of parts to be plated undergoes specific steps in the line. All of the
pieces pass through 'most of the same preparatory stages, while later stages in the
 line are reserved for one type of plated part only. Plated parts are then sent to
other areas of the plant for assembly. Spent solutions in all the tanks, except the
 plating baths, are dumped to the plant's wastewater treatment facility.

 ZINC PLATING LINE

 Larqer-size metal pieces are manually hung on racks attached to an overhead
 conveyor system that is used to dip parts in the 22 tanks that make up this line.
 Plated parts are transferred to the assembly areas of the plant. AH spent tank
 solutions are piped to the plant's wastewater treatment facility.

 FRAME PLATING LINE

 The frame plating line is used to plate nickel, nickel and chrome, and nickel and
 brass onto large display rack frames. Parts are hung on racks as in the zinc-
 plating line. Some of the tanks in this line are bypassed, depending on which type
 of plating is required. Finished parts are transferred to the assembly areas of the
 plant. Spent tank solutions are sent to the plant's wastewater treatment facility.

 PAINTLINE
  Miscellaneous metal pieces that do not require plating are sent to the three-stage
  washer and paint areas. The parts are hung on a small conveyer system that
  transports the parts through an enclosed washer line containing three different
  solution-filled tanks. Spent solutions are dumped directly to the municipal sewer,

  After cleaning and drying, parts are painted using electrostatic powder coating or
  liquid dip painting. Overspray powder is collected and reused. Dragout from the
  dip painting process is collected on cardboard or plastic sheets that are disposed
.  of in a landfill. After drying, the painted parts are transferred to the assembly areas
  of the plant.

  WASTE MANAGEMENT ACTIVITIES
 " ' • The plant operates an electrostatic powder paint system to reduce the
        amount of paint wastes it generates.

     •  The plant uses water-based, nonhazardous liquid paints.

     • Filtering systems recover zinc and nickel from spent plating solutions.
                               ...y7 }WAST£.MttffMEAtrON IN THE METAL FINISHING INDUSTRY
                               "1C"     "••

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       •  Cyanide-laden brass plating water is stored in a holding tank and used as
          rinse water by several of the plating line stages, ,
                                    -     "     "'" '      "    "?'-'   "     '   '      ....""
       •  All wastewater is treated on site before release to the municipal sewer.

       •  A natural gas-fired dryer is used to reduce the volume of sludge resulting
          from the filter press operation.           ,,                   :


    WASTE MINIMIZATION OPPORTUNITIES

    Table 2 shows the opportunities for waste minimization at the plant. The type of
    waste, the minimization opportunity, the possible waste reduction, and its
    associated savings and implementation cost, including its payback time, are
    presented,^ the table. The quantities of waste currently generated by the plant
    and possible waste reduction depend on the plant's production level. All values
    should be considered in this context.

    It should be noted that the economic savings associated with each waste
    minimization opportunity, in most cases, results from the need for less raw
    material and from the reduced present and future costs associated with treatment
    and disposal. Other savings that are not quantifiable include a wide variety of _ *
    possible future costs related to changing emissions standards as well as the costs
    associated with liability and employee health. It should also be noted that the
    savings given for each opportunity reflect the savings achievable when
    independantly implementing each waste minimization opportunity; they do not   .
    reflect duplication of savings that would result when the opportunities are
    implemented as a package.         '
                                       Table2
                       Waste Minimization Recommendations
                                    (Sheetlof2)
 Present Practice
 Contaminated plating, wash, and
 rinse water from the barrel, zinc,
 and frame plating lines and
 contaminated wash and rinse
 water from the paint line are
 treated on site and sewered.
 As the nickel plating baths In the
 barrel and frame plating lines
 becoms contaminated, they are
 emptied'into dedicated filtering- ,
 units used to recover a larger
 portion of the particulata nickel in
 the solutions. The filtering units
 are periodically backflushed with
 a weak acid solution., The acid
 solution, which contains
 contaminants, is sent to the
 plant's wastewater treatment
 facility. Currently, a significant
 amount of nickel is discharged in
 the'wastewater sludge which,  as
 a result, is classified as a
 hazardous waste.
Proposed Action
Install a piping system to recycle
treated wastewater within the
•plant to reduce purchases of
water. If necessary, improve the
current methods of wastewatar
filtering to provide sufficiently
clean water.
Modify the ptating lines in
question to incorporate the
utilization of a zero discharge
recovery (ZDR) system. It is
recommended that the system
use reverse osmosis technology
to recover plating bath solutions
at plant-specific concentration
levels. The system will operate in
a closed-loop manner. There-
fore, the amount of nickel
discharged to the wastewater
treatment facility will  be reduced.
A portion of the chemicals\
required by the baths and by the
water treatment facility will no
longer be needed. Approximately
the same amount of  sludge will .
be generated, but it will be'--,
classified as nonhaz:
Waste Reduction and
Associated Savings

Estimated waste reduction =
3,114,290 gallons per year (gal/
yr); Net raw material cost savings
= $11,120 per year; Operation
cost = $3,840 per year; Total cost
savings = $7,280 per year;
Implementation cost = $56,380
per yean Simple payback '» 7:8
years

Estimated, waste reduction =
none; Waste disposal cost
savings ~ $24,460 per year; Net
raw material cost savings »
$6,250 per year; Operating cost =
$8,000 per yean Total cost
savings = $22,710 per year;
Implementation cost = $70,000;
Simple payback = 3.1 years
CASESTUD/ES
                                                                                                        11
                                                                                            ~-T

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                                                                Table 2
                                              Waste Minimization Recommendations
                                                             (Sheet 2 of 2)
                      Present Practice
                      Add wash tanks, which are used
                      in each of the plating lines (or
                      cleaning of metal parts, are sent
                      to the wastewater treatment
                      facility as they become contami-
                      nated.
                      Rinsing in the plating lines is
                      accomplished by dipping parts in
                      rinse tanks. As a result, consider-
                      able dragout and contamination
                      occur. Spent water from the
                      rinsing tanks is dumped to the
                      onsite wastewater treatment
                      facility, treated, and released to
                      the municipal sewer.

                      Dragout in the three plating lines-
                      current accounts for an estimated
                      10 percent loss in chemical
                      solutions.
                      Various tanks in the plating and -
                      paint lines are steam heated.
                      Condensate is not returned to the
                      boiler because of concerns about
                      possible contamination. It is sent
                      to the waste treatment facility.
Proposed Action
Recover and reuse the spent salt/
acid solution from the contami-
nated wash tanks. It is estimated
that 70 percent of the acid salt
can be recovered using  an
evaporator and reused. Implemen-
tation of this recommendation will
lead to a reduction in the amount
of acid and salt purchases.

Wherever possible, modify the  .
zinc and frame plating lines to use
spray rinsing techniques instead
of dipping objects in tanks.
Install rinse devices above each
plating and wash tank in the zinc
and frame plating lines to spray
water on parts as they are  '
removed from tanks. As a result,
plating solutions will be  returned
to their tanks before dragout
occurs.

Install individual heat exchangers
to serve each heated wash tank
and plating bath. The proposed
units should transfer heat from
the main steam line to smaller
lines feeding each tank. There-
fore, the steam will not come in
contact with any process fluids
and can be returned to the  boiler.
Waste Reduction and
Associated Savings

Estimated waste reduction = 42
gal/yr (waste solids) + 30,860
gal/yr water; Waste mansigement
cost savings = $390 per year;
Net raw material cost savings =
$7,700 per year; Total cost
savings = $8,090 per year;
Implementation cost = $29,440;
Simple payback = 3.6 years

Estimated waste reduction =
617,760 gal/yr; Net raw material
cost savings = $2,200 per year;
Implementation cost = $16,900;
Simple payback » 7.7 years
Estimate waste reduction =
none; Net raw material cost
savings = $2,800 per year;
Implementation cost = $17,940;
Simple payback = 6.4 years
Estimated waste reduction =
262,000 gal/yr; Net raw material
cost savings » $940 per year;
Energy cost savings - $870 per
year; Boiler feedwater chemical
cost savings = $3,500 per year;
Total cost savings » $5,310 per
year; Implementation  cost =
$33,700; Simple payback = 6.a
years  •

12
                            |jONy» THE^ETVU. FRESHING INDUSTRY

                            •*.   ***&    "^

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ATTACHMENT A
Information on
Accessing Pollution
Prevention Information
Clearinghouses

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ATTACHMENT B
Survey


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                     MAILING-LIST FOR FUTURE PUBLICATIONS
Name:  '•  • 	•    	-  -    •  '. - .  X3raani"zation;

Positipn:  .	 .' ' "	;	  Address:  	

.Phone:      • .       	•_i	;	•     ' ...- ;~    :	

Fax:      •	•    	;	1      -    ' ._	
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    »                    Please help us by answering the following questions:


A.-.1.  PROFILE OF YOUR ORGANIZATION

     Trade association-        ''     '  /  /  Business                 7 /  Governmental-office
/ /  Other      .  '   •    '   -•   ''•.-'    '•   '•  -' -.- -: •  -'   '   '    ••'-''/.•.
         /      - -               .        ,       •  -       .        -  - -       '        ,

What product or  service does your business/organization provide?       "	  '  •'  	    •
 How old is your business/organization?  	1_ years
                              - . •   . ' . •  - .-•    ',••''  ^ -
 How many employees.work in your business/organization?
 B.- ': TRAINING                         .         _    .   .  ^   .     .

 'J.S. EPA and SEDESOL plan to add sections to this manual to  support other industries in the border-
 area.  Which industries  should be addressed next?    .         .                    .
 7  /  Agricultural'.Chemical-s      / /  Wood Finishing     •/../' Other    • •       	'.	
 '             '     '      "                        '                    '      '   '
 *?hat type of training would you attend?        V                 ,
                                         r     "    •   ,  ,     -   '  . , '
 /  /  Technical workshops    / /  deneral training    / /  None .'./"/  Other
      EPA and SEDESOL are  considering holding training sessions on "pollution prevention.
      information would be ••-useful to you in                         '
                                        - .

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                                            - 2 -
C.    USEFULNESS OF MANUAL
Did you find the  format of this manual useful? '   / / Yas      / /Ho.
Did you find its  content useful?   / / Yes      / / No
How would you improve it?  	_	—	•	
What other information should be included?
Who else should receive  this manual?
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Address:    __	_	
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                                                                                  Here
                                            HILARY  LAUER
                                            .POLLUTION  PREVENTION COORDINATOR
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                                            SAN  FRANCISCO CA 94105-3901
                                           (Place tape here)

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-FOLLUTIQN PREVENTION
          "*" •»?• f VV
                            APPENDIX A
                            Referenqing Additional
                            Information

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N. .

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 APPENDIX A: ADDITIONAL INFORMATION

     The following are additional documents on pollution prevention that you may find
     useful. Unfortunately, at this time they are only available in English. Copies of
     documents with EPA document numbers may be obtained from EPA Center for
  x   Environmental Research Information (CERI) or the Pollution Prevention Information
     Clearinghouse (PPIC). Copies of documents with Pollution Prevention Information
     Exchange System (PIES) numbers may be obtained through PPIC/PIES.

     •EPA CERI Publications Unit       PPIC'                   PIES        .
     •26 West Martin Luther King Drive   401 M Street"            Technical Support Office
     Cincinnati, OH 45268             Mailcode PM221A         SAIC   .   •'
     (513)569-7562          ;       Washington, D.C. 20460    7600-A Leesburg Pike   '.
                                   (202)260-1023           Falls Church, VA 22043  .
                                                 -   '".'  :  (703)821-4800
   GENERAL INFORMATION:
     1.  Guides to Pollution Prevention: The Metal Finishing Industry
         U.S. EPA Office of Research and Development
         EPA/625/R-92/011
     .    October1992      .                             ,
     2.  Waste.Minimization in Metal Parts Cleaning                                .    .
         U.S. EPA Office of Solid Waste and Emergency Response
  :       EPA/530-SW-89-049                 .        •-'•.'.
.         1989      •  •  .          ;,.-.'     ,   '   "       .'-.'.  '.;
     3.  Waste Audit Study—Metal Finishing Industry
 '"•..     California Alternative Technology Section and U.S. EPA
       :  PIES#005-073-A                    .                   ,      , .      .
      *  1988       .          •    ' :  : ••.:".'   •''•"•'       ,        ,   .
     4.  Waste Audit Study—Printed Circuit Board Manufacturers          ,          '    ,
         California Alternative Technology Section and U.S..EPA                  ;
        ' PIES#005-006       ,        ,_'   '•  '
        • 1987   . '•   ..                       .     -•.'•-
      5.  Source Reduction of Chlorinated-Solvents—Electronic Products Manufacture and
         Solvent Cleaning     •-..-.      '            ,                        . .-  .
         Metropolitan Water District of Southern California & The Environmental Defense Fund
         PIES'#609-008-A and PIES #609-005-A
         1990               "      .'.•'.--..    '        ',".'.      '   .-.

 -    6.  Facility Pollution Prevention Guide
         U.S. EPA Off ice of Research and Developnnent               -       .
         EPA/600/R-92/088     ,          .    -,"•-.            •     ,     ;   ,
         May 1992--;'-"-••'       ;  ,'-  -..•-     '   -  .        ;    •


    MACHINING
      7: J. T. Johnson, Cincinnati Milacron Products Division. "A Comprehensive Strategy for an
         Overall Program of Metal Working Fluid Management". Cincinnati, OH,1985.


    SURFACE PREPARATION               X
      8.  R. Schecter and G. Hunt, North Carolina Pollution! Prevention Pays Program. "Case
          Summaries of Waste Reduction by Industries in the Southeast". Raleigh, NC. 1989.   .
      ,    Page 40. (PIES #112-003-A)
  APPENDIX A

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SOLVENTUSAGE

   9.  L. Traverse, Massachusetts Office of Safe Waste Management. "Creative Source
      Reduction Techniques". Third Annual Massachusetts Hazardous Waste Source
      Reduction Conference Proceedings. Boston, MA. October 23,1986. (PIES #022-012)

   10. R. Schecter and G. Hunt, North Carolina Pollution Prevention Pays Program. "Case
      Summaries of Waste Reduction by Industries in the Southeast". Raleigh, NC. 1989.
      Page 39. (PIES #112-003-A)        .-...''

   11. C. H. Fromm, S. Budaraju and S. A. Cordery, Jacobs Engineering Group. "Minimization
      of Process Cleaning Waste". Solvent Waste Reduction Alternatives Seminar, Speaker
      Papers. Washington, DC. March 1988. (PIES #005-012-A-OOO)

   12 E A Rodzewich. "Source Reduction—Parts Cleaning". Solvent Waste Reduction
      Alternatives Seminar, Speaker Papers. March 1988. (PIES #005-012-A-OOO)

   13. Jacobs Engineering Group, Inc.-for (U.S. EPA), Hazardous Waste Engineering
      Research Laboratory, Office of Research and Development. Waste Minimization Audit
      Report: Case Studies of Solvent Wastes from Parts Cleaning and from Electronic
      Capacitor Manufacturing Operations. Cincinnati, OH. (PIES #010-003-A)

   14. Institute for Local Self-Reliance. "Engine and Plumbing Parts Manufacture, Case Study
      60", Proven Prof its from Pollution Prevention: Case Studies in Resource Conservation
      and Waste Reduction, Volume II. Washington,  D.C. 1989. (PIES #306-001 -A)

   15. North Carolina Department of Environment, Health, and Natural Resources: Pollution
      Prevention Program. Managing and Recycling Solvents in the Furniture Industry.
      Raleigh, NC. May 1986. (PIE'S #034-018-A) '

   16. Hackney, Pollution Prevention Challenge Grant Program, North Carolina Department -
      of Natural Resources. "Pilot Study of Solvent Recovery for Use in Paint Equipment
      Cleanup". December 1986. (PIES #034-050-A-000)

   17. N. H. Frick and G. W, Gruber, PPG Industries,  Inc. Solvent Waste Minimization by the
      Coatings Industry. Pittsburgh, PA. March 1988. (PI ES #800-01)

   18. California Department of Health Services, Alternative Technology Section, Toxic
      Substances Control Division, Wasfe Audit Study: Automotive Paint Shops. January
      1987. (PIES #005-005)

   19. M. Drabkin and P. Sylvestri, U.S. EPA Hazardous Waste Engineering Research
      Laboratory, Office of Research and Development. Waste Minimization Audit Report:
      Case Studies of Minimization of Solvent and Electroplating Wastes at a DQD
      Installation. Cincinnati, OH. 1989. (PI ES #101 -036-B)

  . AQUEOUS CLEANERS

   20. K. B. Patterson and D. E. Hunt, U.S. Air Force, AGMC/MAQSE, Newark Air Force
   •  Base, OH. 'The Cyl-Sonic Gleaner: Aqueous Ultrafiltratiori Cleaning Using
      Biodegradable Detergents". Process Technology '88: The Key to Hazardous Waste
      Minimization, Air Force Logistics Command. Sacramento, CA. August 15-18,1988.
      (PIES #100-100-0)

   21. T. Smietana, Office of Safe Waste Management Trichloroethylene Elimination Case
      Study: Electric Furnace #2 Bright Anneal Line Industrial Metals Department of Texas
      Instruments, Inc.," Third Annual Massachusetts Hazardous Waste Source Reduction .
      Conference Proceedirigs^October 23,1986. (PIES #022-012)
                .             x ,           ,  '   ,    i                     '
    WASTEWATERS

    22. Massachusetts Departmentof Environmental Management, Office of Safe Waste
       Management. Preliminary Report: Phase I Source Reduction Activities, Southeast
       Platers Project. Case'Study B. July, 1988. Page 3. (PIES #022 003-A)

                                     WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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   23. North Carolina Department of Naturalflesources and Community Development.   .
       "Water Conservation for Electroplaters: Counter-Current: Rinsing". Raleigh, NC. 1985.
       (PIES #034-024A)   -     '"',-'           •-•'.•-.•.           '    :

   24. North Carolina Department of Natural Resources and Community Development "Water
       Conservation for Electroplaters: Rinse Tank Design". Raleigh, NC. 1985. (PIES #034-
  , ,    026A),   .  •' '     .-•-..    .      "--..''•';•'"               •'-..'"
   25. Office of Safe Waste Management, Massachusetts Department of Environmental
       Management. 'The"Bobbins Company: Wastewater Treatment and Recovery System,
       A Case Study." Raleigh, NC. 1985. (PIES #034-0266)          ,          .

   DECREASING
                                          1  '                   ''                *
   26: G. Hunt, North Carolina Department of Natural Resources and Community
       Development. "Accomplishments of North Carolina Industries—Case Summaries".
       Raleigh, NC. January 1986, p. 22. (PIES #034-010)

   27. Hazardous Waste Reduction Program of the Oregon^ Department of Environmental
       Quality. 'The Tektonix Payoff". Salem, OR. June 1988. (038^303-A-OOO)

 " 28. United Nations, Economic and Social Council,"Economic Commission for Europe.
       "Compendium on Low- and Non-Waste Technology: Elimination of Chlorine by the Use
       of Fumeless In-line Degreasing in the Aluminum Industry". Geneva, Switzerland. 1983.
       (PIES #400-103)          -

    29. New Jersey Hazardous Waste Facilities Siting Commission, Hazardous Waste Source
       Reduction and Recycling Task Force". A Study of Hazardous Waste Source Reduction
       and. Recycling in Four Industry Groups in New Jersey. Newark, NJ. April 1 987. Case -
     .. studyD4.1,p.30.-(PIES#031-001-A)''   .             ,      '                .  .

    30. S. P. Evanoff, et. al. "Alternatives to Chlorinated Solvent Degreasing—Testing,
       Evaluation, and Process Design" Process Technology '88. Sacramento, CA. August
       15-18,  1988. (PIES #10.0-100-D)


  SURFACE TREATMENT AND PLATING

    ELECTROPLATING                          .          ...     "

    31. G. Hunt, et al., North Carolina Department of Natural Resources and Community
       Development. "Accomplishments of North Carolina Industries—Case Summaries".
       Raleigh, NC. January 1986, p. 22. (PIES #034-010)     ;

    32. United Nations, Economic and Social Council, Economic Commission for Europe
       "Compendium on Low- and Non-Waste Technology: A Low-Waste Electroplating
       Process". Geneva, Switzerland. 1985. (PIES #400-125)

    33. D. HuisinghvL. Martin,H. Hilger, N. Seldmars The Institute for Self-Reliance. "Proven
        Profit from Pollution Prevention". Washington, D.C. 1985, Case Study 26, Page 103.
        (PIES#3Q6r001-A)    ,'-"''."

    34. G. F. McBae. "In-Process Waste Reduction: fart 1 —Enviroscope," Plating and Surface
        Finishing, June 1988.             ..    ,  :
    35. David Wigglesworth, et.al., Alaska Heatth Project. "Waste Reduction Assistance
        Program (WRAP)pn-Srte Consultation Audit Beport: Electroplating Shop". Anchorage,
        Alaska. April 7,1987, pp. 17.-(PIES #002-016-A-001)

     36. Edward Saltzberg, Ph.D., Science Applications International Corporation. "Methods to
        Minimize Wastes From Electroplating Facilities", Process Technology '89: The Key to'
       ^Hazardous Waste Minimization, Air Force Logistics"Command. Sacramento, CA.  /
        August 15-18,1988. (PIES #100-100-D)
APPENDIX A

-------
 37. Hubbard Enterprises, San Diego County, Department of Health Services. "Minimizing
    Waste from an Electroplating Operation", Pollution Prevention, A Resource Book for
    Industry. San Diego, CA. 1990. (PIES #005-079-A-000)

 38. Jerome Kohl, et. al., North Carolina State University,'School pf Engineering. "Reducing
    Hazardous Waste Generation with Examples from the Electroplating Industry*. Raleigh,
    NC. 1986.

 39. Office of Safe Waste Management, Massachusetts Department of Environmental
    Management. "Source Reduction Recommendations for Precious Metal Platers."
    Boston, MA. 'April 1988. (PIES #002-012)                         -  .,

 ELECTROPLATING—CHROMIUM

 40. D. Achman, Minnesota Technical Assistance Program. "Reducing Chromium Losses
    from a Chromium Plating Bath", Minnesota Technical Assistance Program Summer
    Intern Report. Summer 1987. (PIES #709-030)                         ;

 41'. United Nations Economic and Social Counsel. "Use of an Evaporator in Chromium
    Electroplating", Compendium on Low- and Non-Waste Technology. Monograph ENV/
    Wp.2/5/Add.47. Geneva, Switzerland. 1988. (PIES #400-125)

 ELECTROPLATING—-CYANIDE-CONTAINTNG WASTES

 42. L. E. Vaaler. Office of Safe Waste Management. "Prospects for Developing Substitutes
    for Cyanide-Containing Electroplating Baths", Third Annual Massachusetts Hazardous
    Waste Source Reduction Conference Proceedings. Boston, MA. October 23,1986.
    (PIES #022-012)

 43. U.S. EPA Research and Development, Risk Reduction Engineering Laboratory.
    "Waste Minimization Audit Report: Case Studies of Minimization of Cyanide Waste
    from Electroplating Operations", Project Summary. Cincinnati, OH. January 1988.  .
    (PIES #101-023-6)
   ,i                            '                            -'   '

 ELECTROPLATING—NICKEL

 44. Minnesota Technical Assistance Program. Metal Recovery: Metal Finishing Shop.
    Minneapolis, MN. September 1988. (PIES #709-017)

 45. P. Pajunen, Eco-Tech Ltd., and E. Schneider, Hewlett Packard, American
    Electroplaters and Surface Finishing Society and U.S. EPA. "Copper and Nickel
    Removal in Printed Circuit Board  Processing by Ion Exchange and Electroforming",
    Ninth AESF/EPA Conference on Environmental Control for the Metal Finishing
    Industry. January 25-29,1988.

 46. T. Nadeau, et. al. "Copper, Nickel and Chrome Recovery in a Jobshop to Eliminate
    Waste Treatment and Sludge Disposal", Third Annual Massachusetts Hazardous
    Waste Source Reduction Conference Proceedings, Office of Safe Waste Management.
    Boston, MA. October 23,1986. (PIES #022-012)

, 47. Minnesota Technical Assistance Program. Metal Recovery: Ion Exchange.
    Minneapolis, MN. September 1988. (PIES #709-019)

 48. T. V. Trah, et al. "Recovery of Nickel Salts by Electrodiafysis Reversal Process,"
    Presented at 73rd Annual AESFTechnical Conference and Exhibit of Surface
    Finishing. The American Electroplaters and Surface Finishers Society Bulletin: TP 334-
    ST. June 23,1986. (PIES #222-001-A-001)
                     '    X           '      '          '              •
 ELECTROPLATING—GALlMIUM

 49. North Carolina Pollution Prevention Program. "Potential Recovery and Reuse of
    Cadmium from an Electroplating Bath". Pollution Prevention  Challenge Grant Program.
    Raleigh, NC. December 1987. (PI ES #034-050-A-000)
                                   „•             i.

                                  WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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    FT FCTROPLATING—ZINC           ,     .

    :50 Hazardous Waste Reduction Program, Oregon Department of Environmental Quality.
       Guidelines for Waste Reduction and Recycling: Metal Finishing. Electroplating. Printed
       Circuit Board Manufacturing. Eugene, OR. Jyly 1989. (PIES #038-010)        -
    ;             •                               -*           .           -
    51: Tom Nadeau, et.-a'l. "Copper, Nickel and Chrome Recovery in a Jobshop to Eliminate
       Waste   -                .              ;,   .             '        ,.       ,

    52. Treatment and Sludge Disposal", Third Annual Massachusetts Hazardous Waste
       Source Reduction Conference Proceedings, Office of Safe Waste Management.
      ..Boston, MA. October 23, 1986. (PIES #022-012)             ,

    CONTINUQUS HARDENING                                    '

    53. United Nations, Economic and Social Council, Economic Commission for Europe.
       "Compendium on Low- and Non-Waste Technology: Continuous Hardening and Zmc-
       Goating"."Geneva, Switzerland, 1981. (PIES #400-103)    •

    ZINC COATING

    54. United Nations, Economic and Social Council, Economic Commission for Europe
       "Compendium on Low-and Non-Waste Technology: Continuous Hardening and Zinc-
       Coating". Geneva, Switzerland, 1981. (PIES #400:103)     •   '       '            '

    BRITE DIP BATHS

    55. institute for Local Self-Reliance. "Engine and Plumbing Parts Manufacture, Case  •
       Study 60", Proven Profits from Pollution Prevention: Case Studies in Resource
    ,  : Conservation and Waste Reductionf Volume II. Washington, DC. 1989. (PIES #306-
       ,001-A)       '                        '              .               .

    ETCHING

    56. Minnesota Technical Assistance Program, University of Minnesota. "Metal Recovery:
      ' Etchant Substitution". Minneapolis, MN. 1989/(PIES #709-014-A-OOO)

    57. A. Boyce, Tekronix, Inc. and D.-Ji Kavanaugh, CH2M Hill Industrial Design
       Corporation. "Electrolytic Regeneration of Chromic/Sulfuric Acid Etchant," Ninth AESF/;
       EPA Conference Environmental Control for the Metal Finishing Industry. Americaa
       Electroplaters and Surf ace .Finishing Society and U.S. EPA, Washington, DC. January
       25-29,1988.    /      •         '           '              '  ;

    58. V. R. Sellers. "Waste Management Alternatives forElectroplatirig and Printed Circuit-
       Board Manufacturing Operations'", Third Annual Massachusetts Hazardous Waste
       Source Reduction Conference Proceedings, Office of Safe Waste Management.
       Boston, MA,pctober 23, 1986.-(PIES #022-012)

    69. Thaddeus Srnietana. 'Tnchlofoethylene Elimination Case Study: Electric Furnace #2
        Bright Anneal Line Industrial Metals Department of Texas lnstruments,.lnc.", Third
        Annual Massachusetts Hazardous Waste Source Reduction Conference Proceedings,
        Office of Safe Waste Management. Boston, MA. October 23,1986. (PIES #022-012)

     CHROME CONVERSION

     60. New. Jersey^Hazardous Waste Facilities Siting Commission, Hazardous Waste,.
        Source Reductiori and Recycling Task ForceN'A Study of Hazardous Waste Source
        Reduction and Recycling in'Four Industry Group's in New Jersey", Case Study 06.1,
        p.33. Newark, NJ. April 1987. (PIES #031 ^001-A)                ,
APPENDIX A

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61. K. Weigel. "Developments in Powder Coating Technology", Metal Finishing. April
   1989. pp. 41-44.                                        "       ,
62. D. S. Tyler, -Volstatic, Inc. "Electrostatic Powder Coating: Finishing for the Future",
   Metal Finishing, January 1985, pp.. 23-26.               ,
63. Hans Sutler, Umweltbundesamt. "Low-Waste Technologies in the Federal Republic of
   Germany", The Environmental Professional, Volume II, pp.  190-198. Berlin, Germany.
   1989. (PIES #458-006-A-001)

64. North Carolina Department of Environment, Health, and Natural Resources: Pollution
   Prevention Program.' Managing and Recycling Solvents in the Furniture Industry, May
   1986. (PIES #034-018-A)                                       ,
65. Hazardous Waste Reduction  Program of the Oregon Department of Environmental
   Quality. 'The Tektonix Payoff. Salem, OR. June 1988. (PIES #038-003-A-000)

66. Mark Manzione, Brown and Caldwell Consulting Engineers. "Waste Minimization for
   Electroplating and Aircraft Paint-Stripping Wastewater Treatment", Process
   Technology '88: The Key to Hazardous Waste Minimization, Air Force Logistics
   Command. Sacramento, CA.  August 15-18, 1988. (PIES #100-100-0)

67. Hackney. Pollution Prevention Challenge Grant Program, North Carolina Department
   of Natural Resources. "Pilot Study of Solvent Recovery for Use in Paint Equipment
   Cleanup". Raleigh, NC. December 1986. (PIES #034-050-A-000)'

68. California Department of Health Services, Alternative Technology Section, Toxic
   Substances Control Division. Waste Audit Study: Aiitomotive Paint Shops.
   Sacramento, CA. January 1987. (PIES #005-005)                             -

69. United States Environmental Protection Agency, Hazardous Waste Engineering
   Research Laboratory, Office of Research and Development Waste Minimization. Audit
   Report: Case Studies of Minimization of Solvent Waste from Parts Cleaning and from
   Electronic Capacitor Manufacturing Operations. Cincinnati, OH. November 1987. (PIES
   S101-008-A).
                                   WASTE -MINIMIZATION IN THE METAL flNISHING INDUSTRY

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;:-


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;.v^--yvv',.V-?:.; SC .-.;
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INTRODUCTION

     The production of economically competitive products is the?driving force behind
     any successful business. Quite often the manufacturing process requires the use
     of various chemicals. The purchase and storage of these chemicals, their use in
     the process, and the ultimate disposal of the waste created by the manufacturing
     process can present many problems. These problems include financial concerns,.
    : as well as issues associated with environmental management and worker health
     and safety. Pollution prevention occurs when action is taken to reduce the waste
     created by manufacturing processes. It  includes practices that reduce the use of
     hazardous and nonhazardous materials, energy, water, and other resources, as
   :  well as those practices that protect natural resources through conservation or
     -more.efficient use.

     Because of the enormous potential for pollution prevention along the United States
     and Mexican border, the U!s. Environmental Protection Agency and SEDESOL
     established a Pollution Prevention Workgroup in February 1990 to promote and
     coordinate the reduction of. pollution through a broad range of approaches:
 ! *  technical assistance, training, public and private sector pollution prevention
     awareness programs, assessment of pollution prevention opportunities, policy
     development and institutional support, and technology development and
     investment activities.                       -

     The purpose of this first manual is to provide pollution prevention information for
   •  the metal finishing industry. The manual will be expanded in the future  to include
     other industries that are typical in the border area, such as the chemical
   -  manufacturing and wood finishing industries. The manual contains the following
     sections.                                   ,

        Section I      The Goals and Benefits of Pollution Prevention

        In this general introduction/the term "pollution prevention" is clarified. This
        section also includes an overview of the benefits of applying pollution preven-
        tion techniques.

         Section  II      Waste Minimization in the Metal Finishing
            ,             Industry

         This technical section contains descriptions of various processes associated
         with the metal finishing industry and pollution prevention options for that indus-
         try: This section may be of particular interest to process engineers.

         Sectional    CaseStudies

         This section includes specific examples of companies that have used pollution
         prevention techniques. These case studies describe the benefits, particularly
         cost savings, these companies have achieved.                .           .
                                                -
  INTRODUCTION

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    Attachment A Information on Accessing Pollution
                   Prevention Information Clearinghouses

    This section describes how to access the International Cleaner Production
    Information Clearinghouse (ICPIC) database, which is an international cleanng-
    house for pollution prevention information.

    Attachment B Survey

    PLEASE COMPLETE THE SURVEY INCLUDED IN THIS SECTION. Your
    response provides valuable information for evaluating the usefulness of this
    manual. Additionally, by mailing in the survey, your name will be placed on a
    mailing list for updates to the manual and other documents as they become
    available.

    Appendix A   Referencing Additional Information

    This section lists additional technical documents pertaining to pollution preven-
    tion opportunities for the metal finishing industry, and other information. Cur-
    rently these documents are available in English only.


SECTION 1: THE GOALS AND BENEFITS OF POLLUTION

PREVENTION
  The goal of a pollution prevention program is to minimize all waste P^1^    .
  PoHuUon prevention includes any action a company takes to reduce the amount of
  waste created by a manufacturing process prior to recycling, treatment, or disposal
  of the waste. To effectively accomplish this, the program must be an ongoing,
  comprehensive assessment of the operations at a facility.

  pFMFFITS OF A POLLUTION PREVENTION PROGRAM
  Both businesses and governments have strong incentives to reduce the toxicity'  _
  andI aheervahma of the waste they generate. The cost of Pi^lucngefdmrt w,ll
  decrease as pollution prevention measures tower operating costs. Therefore,
  companies with an effective, ongoing pollution prevention plan will have a
  significant competitive edge.
  The overal benefits of a polluttori prevention program, discussed in more detail
   betow, include the following:
     •  protecting human health and environmental quality

     •  Reducing operating costs                                  -     \

     m  Improving employee morale and participation

     •  Enhancing your company's image in the community

     • Reducing the potential for penalties and fines
                                 WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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   PROTECTING HUMAN HEALTH AND ENVIRONMENTAL
   QUALITY
   Reducing the waste released to air, land, and water will help the environment and
   protect human health. Typical harmful, pollutants that can be reduced significantly
   by pollution prevention techniques include the following:

     •  Air emissions — solvent fumes, fine.particulates, 'and carbon monoxide

     •  Land disposal —heavy metarsludge, waste solvents, and debris

     •  Water disposal —wastewater contaminated with heavy metals, cyanide, and
        other toxic materials                             ;'  "  ''  '.

   The health and safety of employees can be affected by poor ventilation,          ,
   mishandling of chemicals, and a lack of proper safety equipment. An informative
   employee training program is an important way to reduce accidents. Reducing the
   amount of chemical materials and wastes at a facility is also beneficial because it
   reduces the 'amount of space required for storage as well as the potential for
   accidental spills. Furthermore, there may be a reduction in hazardous waste
   transportation requirements if the volume of pollution is minimized.

   REDUCING OPERATING COSTS

   An effective pollution prevention program can yield cost savings that will more than
   offset program development and implementation costs. Cost reductions may be
   immediate savings that appear directly on the balance sheet or anticipated savings
   based on avoiding potential future costs. Cost savings are particularly noticeable
   when the costs resulting from the treatment, storage, or disposal of wastes are
   allocated to the production unit, product, or service that produces the waste.

   Materials costs, or the costs to purchase materials,1 can be reduced by adopting
   production and packaging procedures that consume fewer resources. This
   approach uses resources more efficiently and creates less waste. As wastes are
   reduced, the percentage of raw materials converted to finished products
   increases, this leads to a proportional decrease in materials costs.

   Waste management and disposal costs may be reduced when less waste is
   produced. Required procedures for proper handling of the waste at the facility, as
   well as specific treatment, disposal and transportation methods ^re typically labor
    intensive and very costly. These requirements and the associated costs are
    expected to increase.

    Production costs can be reduced through a pollution prevention assessment.
    When people examine production processes from a fresh perspective, they find
    opportunities for increasing efficiency that might not otherwise have been noticed.
    Production scheduling material handling, inventory control, and equipment
    maintenance are all areas where facilities can work to reduce the production of
    waste of all types, arrf thus control the cx>sts of production.

    Energy costs will decrease as the facility implements pollution prevention
    measures in various production lines. In addition, companies can reduce the
    energy used to operate the overall facility by doing a,thorough assessment of how
    operations interact.               -         "x
INTRODUCTION

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  IMPROVING EMPLOYEE MORALE AND PARTICIPATION

  Employees are likely to feel better about their company when they believe that.
  management is committed to providing a safe work environment and is acting as a
  responsible member of the community. By participating in pollution prevention
  activities, employees have an opportunity to be part of a "team," and interact
  positively with co-workers and management. Helping to implement and maintain a
  pollution prevention program  should increase each employee's sense'of
  commitment to company goals..This positive atmosphere helps to retain a
  competitive work force and to attract high-quality new employees.        '.

  ENHANCING THE COMPANY'S IMAGE IN THE COMMUNITY

  The quality of the environment has become an issue of greater importance to
  society. Your company's policy and practices for controlling waste increasingly
  influence the attitudes of the community at large.

  Community attitudes are more positive toward companies that operate and
  publicize a thorough pollution prevention program. If a company creates
  environmentally compatible products and avoids excessive use of material and
  energy resources, the company's image will be enhanced in both the community
  and with potential customers and consumers.

  REDUCING THE POTENTIAL FOR PENALTIES AND FINES

  Mexico's environmental laws include administrative penalties that entitle
  government inspectors to require temporary or permanent closure of businesses
  that are out of environmental compliance. A clearly written pollution prevention
  plan that includes standard operating procedures that comply With environmental
  laws and regulations is very helpful. By following the plan, a company is less  likely
  to incur any violations and associated penalties.


WHAT IS POLLUTION PREVENTION?

  , Pollution prevention (also known as "source reduction" and."waste minimization")
  is any action that reduces the production of wastes (at their source) that may be
  otherwise released to the air, land, or water. There are two general methods to
  achieve pollution prevention: (1) process changes and (2) product changes.
  Various source reduction changes are summarized in Figure 1.

  Process changes allow resources to be more efficiently used during the '
  manufacturing process. These changes include the following:

     •  Prudent purchasing, where the most  appropriately sized container of new
        material is bought, rather than buying too  much and having to dispose of the
        unused portion

     •  Operational changes, such as reuse  of input materials during production and
        reduction of water consumption in the process lines

     •  Technology changes, such as using  a safer process material

     •  Increase in energy efficiency
                                  WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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                    Figure 1 - Source Reduction Methods
                               Sourc« Reduction
                                    _L
          Product Change*
    Design for less environmental impact
    Increase product life
          _L
   Input Material Changes
   • Material purification
   • Substitution of less
    toxic materials
                      Process Changes
 Improving Operating
     Practices
i Layout changes
i Increased automation
i Improved operating
 condrtions
i Improved equipment
i New technology  •
 Technology Changes
• Operating and
  maintenance
 ' procedures
• Management practices
• Stream segregation
• Material handling
  improvements
• Production scheduling
• Inventory control  :  ;
• Training
• Waste segregation
    Rgure 2 provides morespecific examples of process changes.

    Product changes reduce the volume of pollution when the finished product has
    less of an impact on the environment during the manufacturing phase, as well as
    the uhimate use and disposal of the product. Product changes can indude the
    following:

       •  Development of a toss chemical-intensive product

       •  Development of a higher-quality product that lasts longer

       •  Incorporation of a life-cycle analysis, which includes the use and disposal
         options for the product


  OTHER ENVIRONMENTAL MANAGEMENT STRATEGIES

    There are a number of. pollution control measures that are applied only after
    wastes are generated. They are, therefore, not correctly categorized as pollution
    prevention! Figure 3 provides some examples of procedures that are waste
    management measures;

    It should be emphasized that transferring hazardous wastes to another
    environmental medium is not pollution prevention. Many waste management
    practices to date have simply collected pollutants and moved them from one
    environmental medium to another. For examplte^solvents can be removed from
    wastewater by means of activated carbon adsorbers. However, regenerating the
INTRODUCTION

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                 Figure 2 - Process Change Methods
The following process changes are pollution prevention measures because
they reduce the amount of waste created during production.
The following are examples of input material changes:
   • Stop using heavy metal pigment.
   • Use a less hazardous or toxic solvent for cleaning or as coating.
   • Purchase raw materials that are free of trace quantities of hazardous or
     toxic impurities.              '
The following are examples of technology changes:
   • Redesign equipment and piping to reduce the volume of material con-
     tained, cutting losses during batch or color changes or when equipment is
     drained for maintenance or cleaning.
   • Change to mechanical stripping/cleaning devices to avoid solvent use.
   • Change to a powder-coating system.
   • Install a hard-piped vapor recovery system to capture and return vapor-
     ous emissions.
   • Use more efficient motors.
   • Install speed control on pump motors to reduce energy consumption.
 The following are examples of improved operating practices:
  . • Tram operators.
   • Cover solvent tanks when not in use.
   • Segregate waste streams to avoid cross-contaminating hazardous and
     nonhazardous materials.
   • Improve control of operating conditions (e.g., How rate, temperature,
      pressure, residence time, stofchtometry).
    • Improve maintenance scheduling, record keeping, or procedures to
      increase efficiency.
    • Optimize purchasing and inventory maintenance methods fot input
      materials. Purchasing in quantity can reduce costs and packaging mate-
      rial if care is taken to ensure that materials do not exceed their shelf We.
      Reevaluate shelf life characteristics to avoid unnecessary disposal of
      stable items.
    • Stop leaks, drips, and spills.
    • Turn off electrical equipment such as lights and copiers when not in use.
    •  Place equipment soaato minimize spills and losses during transport of
       parts or materials.
    •  Use drip pans and splash guards.
                                 WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY'

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                  Figure 3 - Other Environmental Strategies

   The following are other environmental management strategies:

   Off-site recycling:                      -
      • Off-site recycling (for example, solvent recovery at a central distillation
        facility) is an excellent waste management option. However, it does create
        pollution during transport and during the recycling procedure.

   Waste treatment:                                               ,

      • Waste treatment involves changing the form or composition of a waste
        stream through controlled reactions to reduce or eliminate the amount of
        pollutant. Examples include detoxification, incineration, decomposition,
        stabilization, and solidification or encapsulation.

   Concentrating hazardous or toxic constituents to reduce volume:

      • Volume reduction operations,  such as dewatering, are useful treatment
        approaches, but they do not prevent the creation of pollutants. For ex-
        ample, pressure filtration and drying of a heavy metal waste sludge prior to
        disposal decreases the sludge water content and wastevolume, but it
        does not decrease the number of heavy metal molecules in the sludge.

   Diluting constituents to reduce hazard or toxicity:

      • Dilution is applied to a waste stream after generation and does not reduce
        the absolute amount of hazardous constituents entering the environment.

   Transferring hazardous or toxic constituents from one environmental
    medium to another:

      • Many waste management, treatment, and control practices used to date
        have simply collected pollutants and moved them from one environmental
        medium (air, water, or land) to another. An example is scrubbing to
        remove sulfur compounds from" combustion process off-gas.
    carbon requires the use of another solvent or heating, transfering the waste to the
    air. In some cases, transfer is a valid treatment option. However, too often.the
    purpose has been to shift a pollutant to a less-tightly regulated medium, In either
    case, media.transfers are-not pollution prevention.

    Off-site recycling is vastly preferable to other forms of waste handling because it
    helps preserve raw materials and reduce the amount of. material that will require
    disposal. However, compared with closed-bop recycling (or reuse), performed at
    the production site, off-site recycling is likely to have more residual waste that
    requires disposal associated with it. .Furthermore, waste transportation and the
    recycling process carry the risk of worker exposure and release to the
    environment.                ,        ' N._ -

    Waste treatment prior to disposal reduces the toxicity and/or disposal-site space
    requirements but does not eliminate all pollutant materials. This includes such
    processes as volume reduction,  dilution, detoxification, incineration, stabilization,
    and other measures.                .  •-•&,    ,                 .   ,
INTRQDUCnON

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                     The pollution prevention hierarchy, represented on Rgure 4, prioritizes waste
                     management options from those that are most environmentally beneficial to those
                     that are least environmentally beneficial. More specific technical information on
                     pollution prevention options for the metal finishing industry is found in Section II of
                     this manual.
                                    Figure 4 - Pollution Prevention Hierarchy
                                       Pollution Prevention Source Reduction
                                               Recycling and Reuse
                                                   Treatment
                                                \
8
                                                      WASTE MINIMIZATION IN THE METAL FINISHING INDlfSTRY

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SECTION II
Waste
Minimization
for the Metal
Industry


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\

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        •,.--.•'-'•-:•  -  :         '•  •'      (((lf{ffl((ff((fffffffffff

       WASTE MINIMIZATION
   ASSESSMENT  PROCEDURES

               MODULEIII
          WASTE MINIMIZATION IN THE METAL
                FINISHING INDUSTRY
                  A JOINT PROJECT OF

               UNIVERSITY EXTENSION
        UNIVERSITY OF CALIFORNIA, RIVERSIDE

         ALTERNATIVE TECHNOLOGY DIVISION
CALIFOFtNIA DEPARTMENT OF TOXIC SUBSTANCES CONTROL

           ,'       UNITED .STATES-'..
        ENVIRONMENTAL PROTECTION AGENCY
                     ,  AUTHORS:
             JON W. KINDSCHY, M.B.A.,CHWS
           UMVERSITY OFCAUFORMA EXTENSIOH, UNtVERSTY OF CAUFORMA, MVERS106


                DAVID RINGWALD, B.S.
                     PROJECT DIRECTOR:
               MOLLY CARPENTER, M.A.T.

                  COMTtNUtNG EDUCATION SPEOAUST     „ 	
           UMVERSITV OFCAUFORNU EXTENSION, UNIVERSITY OF CAUFORMA. »VERSID£
                 MAY  19 91

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\

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ACKNOWLEDGMENTS


   SPECIAL THANKS TO:
       Reviewi

       Kathryn Barwick, California Environmental Protectfon Agency, Department of
       Toxic Substances Control, Office of External Affairs, Office of Pollution
       Prevention and Technology, Development, Sacramento

       Dave Hartley, California Environmental Protection Agency Department of Toxic
       Substances Control, Office of External Affairs, Office of Pollution Prevention
       and Technology Development, Sacramento

       Robert Ludwigs, California Environmental Protection Agency, Department of
       Toxic Substances Control, Office of External Affairs, Office of Pollution
       Prevention and Technology Development, Sacramento

       Andora Sprecher, Comtox Corp., Big Bear City, California

       Kim Wilhelm, California Environmental Protection Agency, Department of Toxic
       Substances Control, Office of External Affairs, Office of Pollution Prevention
       and Technology Development, Sacramento

       Par Formatting and Graphics;

      . Shelley Hall, Publications Department, UCR Extension

       Jack Van Hise, Publications Department, UCR Extension


        PROJECT ADVISORY COMMITTEE MEMBERS                        ;

        John Aubert, General Dynamics, Pomona Division.

        Al Crane, General Dynamics, Pomona Division                i
        Cathy Godfrey, Bourns Incorporated, Riverside

        Jon Kindschy, University of California Extension, Riverside

        Marilyn Kraft, County of San Bernardino, Department of Environmental Health
        Services                                            .
        Robert Ludwig, California Environmental Protection Agency, Department of
        Toxic Substarvces Control, Office of External Affairs, Office of Pollution
        Prevention and Technology Development, Sacramento

        Michael Mettzer, Lawrence Livermore Lab, University of California, Berkeley

        Steve Mercer, formerly with Rohr Industries, Riverside
        JudyOrttung; County of San Bernardino, Department of Environmental Health
        Services .
        Mike  Shetleri Riverside County Health Department, Hazardous Materials
        •Branch          ."'.'•'.    ;..-'.'         --',".,
         Donna Toy-Chen, Board of Public Works, Hazardous arid Toxic Materials
         Project, Los Angeles                 v                  '
               '     •  • - -   - '   '  ',    -  "' .  ' • ^"v,"    "   " •         -"        •
         Linda Verhoeven, Rohr Industries, Riverside V

         Janet M. Weder, Seven W Enterprises and Highland Supply Corp., Redlands
  ACKNOWLEDGMENTS

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            DISCLAIMER

            The statements and conclusions of this report are those of the Regents of
            the University of California and not necessarily those of the State of
            California or the U.S. Environmental Protection Agency. The mention of ,
            commercial products, their sources, or their use in connection with
            material reported herein is not to be construed as either an actual or
            implied endorsement of such products.
                                                                      DISCLAIMER
n                                                             -  '         •    .

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—	—^———    '                   	—  (MMIMMW
CONTENTS               :.  .         \V                 ;     .         .           '  ••-.'.

   INTRODUCTION AND PURPOSE	........*.....		1

   CHAPTER!. DESCRIPTION OF METAL FINISHING
   SYSTEMS
        Metal Cleaning and Stripping	,.„.....	.3        •
           Organic Solvent Cleaning .......:	••• 5 .
           Aqueous Based Cleaning	•	6
           Abrasive and Thermal Methods ..........	-	—	•	— 6
       .'Surface Treatment and Plating	•	 8
           Chemical and Electrochemical Conversion	9
           Electroplating and Related Processes	.....10
           Metallic Coatings.........	:....;.........	,..,.....;.....•	...10
           Case Hardening	....,	„.....:...-....;•:..•<: 10
        Printed Circuit Board Manufacturing	11

   CHAFTERZ WASTE MIMMIZAHON OPTIONS FOR THE
   METAL FINISHING INDUSTRY                 \
        Source Reduction in Cleaning and,Stripping.	..	 13
           Preventing the Need for Cleaning	•	-13
           Solvent Source Reduction	..—-	-••	•	14-
           Aqueous-based Wastes	.	—	.-.-..»...'.	14-
           Abrasives Source Reduction..,..	............/....I............... 15
        Source Reduction in surface Plating and Related Processes..............	15
        ProcessSubstitution...........;.........;.	....;....'.....:...-	 16
        Material Purchase, Storage and Handling .........i...	•.	:......,........:..:. 16
        Avoiding Material Degradation.	..»•	 16
           ManagingjSamples	,..^.....	:..;.............	.;............ 16
       .    Spills ....•S»............	....:	...:....:	.............<;. 18
           Residue^ and Empty Containers.	 18
           Inspections	.......„......;%.-..	 18
         ProcessBaths	;:.'...„.............:!....;'.'...•:.•	18
            Material Substitution	.....:....	.,........;..	^..	..:.... 18
            Extending Solution Life	;	19               •
            Drag-Out Reduction ...........,...:...................\....	20
      "  Rinse Systems-;	.•;...'	';..	........4.,...;:.	..;........„....	22
         Improved Housekeeping	...:.................,..	 22
                                    • -                 *        -     »  "      '     ,.-       f        ' •  • • •
 -CONTENTS      ''      '  .   '        .;:      '   •   •'•"'     .'-'•   ,••'.••-                 .     *"

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Source Reduction in Printed Circuit Board Manufacturing	, 22,
   Product Substitution	r	'•	24
   Cleaning and Surface Preparation	24
 1  Electroplating and Electroless Plating	24
   Pattern Printing and Masking	24
     Etching	••••••	.....24
Recycling and Resource Recovery in Cleaning and Stripping	25
   Solvent Recycling	'.	•	: 25
   Aqueous-based Cleaner Recycling	-	•• 25
Recycling & Resource Recovery in Surface Plating & Related Processes . 26
   Material Recovery and Reuse	26
     Evaporation	•	••	26
    ' Reverse Osmosis	-	•	26
     Ion Exchange	-	-.....,...	•	27
     Electrolytic Recovery	-	•	28
     Electrodialysis	28
   Rinse Water. Reuse	28
Recycling and Resource Recovery in Printed Circuit Board Manufacturing 28
Review Questions	,.	•	••	••	-	31.
References	•	•'•	•	»— 33
Glossary	—•	•	•	35
                               WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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INTRODUCTION AND PURPOSE

     This booklet is part of a project to develop training materials for
     waste generator inspectors. The three training modules address -
     aspects of waste minimization.

  ,   This module outlines the processes involved in metal cleaning, metal
     finishing, and printed circuit board manufacturing and the potential for waste
     minimization within each of these activities. However, the applicability of
    • waste minimization strategies to a particular shop will vary significantly    . •
     depending on such variables as floor space for new equipment, utility service
 .    capacity contractual specifications, or restrictions on wastewater discharge.
     Thus a realistic evaluation of waste reduction potential must include
   .  qualitative information as well as a quantitative evaluation of the costs and
     benefits of proposed changes.               .                   .       _
     This module  is intended to provide the key concepts necessary to familiarize
     the inspector with the scope of the metal finishing industry arid the search for
     viable waste  minimization options:  It will describe the two major categories
     of metal finishing operations, metal cleaning and stripping, and surface
     treatment and plating. An allied industry, printed circuit board manufacturing,
     will also be discussed. Strategies for reducing waste will include examples
      of source reduction, recycling and reuse.. Economic factors which act as
      both a driving force for and a barrier against waste minimization will also be
      discussed. The glossary provides definitions of terms related to the subject
      beyond those used in this module.                ••_,•.

      Accompanying this Module is a Department of Health Services publication  '
                       : Waste Reduction Chprklist & Ass^f?™""* Manual for the
      entitled:
           i Finishinn Industry. It is available in quantity for distribution to metal
      finishers as inspections are completed. Section 1 of the booklet provides a
      checklist of waste minimization opportunities which parallels the discussion
      in this workbook.  Section 2 of the booklet provides a series of tables for
      evaluating the potential applicability of the options discussed in this manual.

      The inspector should be thoroughly familiar with the Department ofHealth
      Services booklet as well as Modules I and ll.of this training senes. Thus, the
      inspector will be prepared to assist the operators of the .facilities inspected in
      their waste minimization opportunity assessments.

       Module III is intended to augment the information in the .Department of
       Health Services booklet and to provide you, as an inspector, with the
       technical background to understand the related processes to maximize your
       effectiveness in enforcing regulations and in contributing to the goals of the
       State in reducing the volume and tox.icity of our industrial waste stream.
Reduce
Volume
Reduce
toxicfty
                                                .\
   INTRODUCTION AND PURPOSE

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WASTE MINIMIZATION IN THE MEWL FINISHING INDUSTRY

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This chapter will:
         Review the metal finishing processes of cleaning and stripping1 and the
         processes of treatment and plating                           •

         Review the printed* circuit manufacturing process
Chapter 1

DESCRIPTION OF METAL

FINISHING SYSTEMS
     There are approximately13,000 metal finishing and printed circuit shops in
     the United States. The U.S. Environmental Protection Agency (EPA)
     estimates that in i986 the metal finishing industry generated 129,000,000
     gallons of metal-bearing waste. The industry includes a vast array of
     .manufacturing facilities. The size of operations ranges from small "mom and
     pop" shops, which only use a few processes and typically do contract work
     for larger companies, to very large operations, which have many finishing
   '  lines using dozens of processes and have hundreds of employees. Almost
     all of these companies have installed wastewater treatment systems to
     comply with the Clean Water Act.  As a result, these companies generate ,
     toxic metal sludges that are regulated pursuant to Resource Conservation
     and Recovery Act. Compliance with these two federal laws, in addition to
     other state, county and local regulations, can require industry to spend 10 to
     15 percent of their sales dollar on compliance. Compliance with the landfill
     ban has caused disposal costs to increase by 25 to 150 percent. These
     facts of life for the metal finishing industry make waste minimization a high
     priority.
Large and
small shops
contribute to
waste streams
   METAL CLEANING AND STRIPPING
      The objective of metal cleaning and stripping is simply to clean both metallic
      and non-metallic surfaces in preparation for subsequent processes. This   •
      generally involves removing contaminants such as rust, paint, old plating
      and a wide variety of "soils".  Removal of soils can be achieved by means of
      using detergents, solvents, chemical reactions, or mechanical action.  In
      surface treatment and plating operations processes are used to impart
      particular characteristics to a material, such as reducing surface reactivity;
      increasing corrosion resistance, strength or conductance; or producing
      desired textures-or colors. Both chemical and mechanical processes are
      used to accomplish these objectives and both produce waste materials
      containing metals and other chemicals, which must be disposed of properly.

      Metal finishing often involves many steps, and there can be cohsiderable
      periods of time between the steps. To protect the metal workpieces over
      these intervals, they are often coated with oils or paints to prevent oxidation
      from occurring while in  storage or in transit. Prior to continuing with the next
      step, these protective coatings must be removed. Also, workpieces that
      must be handled pick up traces of body oils arxfother soils that can interfere
   DESCRIPTION OF METAL F/N/SR/NC SYSTEMS

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  MMl.llimii
  The cleaning
        process
       selected
 depends upon
    the form of
contamination
 with subsequent processing steps. Traditionally, organic solvents have been
 used to remove these materials. These solvents do not add to the metal-
 bearing waste load from metal finishing, but they are considered to have
 significant human health.and environmental risks. This stems not only from
 their toxicrty, but also from their ftammability and resistance to biodegradation.

 Industrial cleaning costs in the metal finishing industry are considerable, but the
 costs of improper or incomplete cleaning of surfaces prior to plating can be even
 higher. For example, early failure of moving engine parts has been traced to
 inadequate surface cleaning, which resulted in excessive wear. The. primary
 cause of the failure of paint and plating to properly adhere is that they were
 applied to a soiled surface.

 The cleaning methods vary considerably depending on the type and quantity of
 the soil, the nature of the base metal and the coating material, as well as the
 shape of the workpiece and its end use.  A cleaning process that proves
 adequate for subsequent anodizing of steel would be totally unsuitable if the
 same workpiece were to be nickel plated.

 In the cleaning process, four forms of contamination must be considered. They
 are grease soil, loosely adherent soil, adherent soil and moisture.  A typical
 workpiece may have a combination of these soils.
    Grease soil - Includes normal lubricating oils, oils used during machining,
    grease used for protection of components during storage and natural oils in
    fingerprint contamination.
    Loose soil - Includes, dust and fine turning and grinding debris from
    machining. These are often found in conjunction with machining oil. This
    form of contamination can be compared to chalk on a chalkboard in that the
    particles adhere loosely to the surface.
    Adherent soil - Commonly includes scale or rust, but might also include
    bumed-on oil or paint that has served its purpose and needs to  be removed.

    Moisture - Normally present in the atmosphere, it may appear as
    condensation on .workpieces or come from machining with water-soluble oils.
    This ubiquitous contaminant can also be blamed for some of the adherent
    soils described above.                                      .

  Each of these types of contaminants and the methods for removing them will be
  discussed in subsequent sections. It should, however, be reemphasized that a
  single form of contamination will seldom be found in practice. A series ,of
  cleaning operations is generally required to fully prepare a metal surface for  its
  final treatment. The order in which the workpieces move through the cleaning
  processes depends on the types of soils present.

  In these processes soils are removed using four different means:  1) solvent
'  action, 2) detergent action, 3) chemical reaction, and 4) mechanical action.
  Some of these may be employed in combination to increase the effectiveness of
  others. For example, ultrasonic vibration, a mechanical action, is  commonly
  used in conjunction with both solvent-based and aqueous-based baths to
  increase their cleaning efficiency.,
                                                 \
                                                             WASTE MINIMIZATION IN THE METAL FINISHING INDUSTTKf

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     ORGANIC SOLVENT ACTION Describes the ability of one material
     (solvent) to easily make a mixture with another material (solute). For the
     purposes of this discussion the solvent and solute are both non-aqueous-
     based.        '             :                : .
     DETERGENT ACTION Describes a substance or mixture of substances
     that removes a soil from a surface and maintains it in aqueous solution.
     Detergents are generally composed of surfactants or alkaline salts and
     caustics, individually or in combination. Surfactants are surface-active
     agents that promote the removal of contaminants from a surface.
     Emulsion cleaners combine surfactants and solvents.

     CHEMICAL REACTION Changes the target soil chemically (e.g.,
     oxidation, reduction) by using chemical or electrochemical processes
     such that the soil is removed from the metal surface and retained in
     solution.                           ,                 .
     MECHANICAL ACTION  Direct contact with a solid material under force;
     or, in the case of ultrasonic vibration, high frequency sound waves  .
     through a liquid medium, to remove the target soil. This includes wiping,
     polishing and blasting.

   There are three primary cleaning processes used for metals: 1) organic
   solvent cleaning, 2) aqueous-based cleaning, and 3) abrasive and thermal
   methods.
   ORGANIC SOLVENT CLEANING
   Solvent cleaning describes the use of solvent to remove oil and grease from
   surfaces. This can be accomplished in a number of ways, including the
   simplest, wipe cleaning, where a cloth is moistened in a solvent and rubbed
   across a surface.  Although still in practice for some heavily soiled
   workpjeces, its effect can be to spread soils to areas that are not.
   contaminated. The same can be said for immersion cleaning where a rack
   of workpieces is immersed in a bath of solvent. The bath quickly becomes
   contaminated with the soil so when the rack is withdrawn and the solvent
   evaporates, a film of soil evenly coats the surface.

   The classical method for the removal of oil and grease from a surface is
   vapor degreasing. It usually consists of boiling a solvent cleaner, generally
   one of the chlorinated hydrocarbons, resulting in the heated vapor phase,
    into .which the contaminated workpieces are inserted. The vapor phase then
    condenses on the cold components to produce a clean hot solvent, which
    dissolves the oil and grease.  As further solvent condenses, h removes the
    dissolved soils.,,                 .                        .

    Historically, the industry has used carbon tetrachloride and other solvents  .
    such as benzene for solvent cleaning. These have now been shown to
    constitute significant health risks and have been removed from the
    workplace. The most commonly used solvents now in use are 1,1,1 -
    trichloroethane (TCA), trichloroethylene (TCE), perchloroethylene (PERC),
    and methylene chloride (METH).  The last three solvents named are rapidly
    disappearing from use for several reasons, including ozone depletion. In
    particular,  trichloroethylene, a carcinogen, has been increasingly replaced
    with substitutes such as methanol and acetone."          ,
Metal
cleaning
methods
DESCRIPTION OF METAL FINISHING SYSTEMS

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AQUEOUS-BASED CLEANING
Aqueous cleaning comprises a wide range of water-based cleaning methods
that use detergents, acids, and alkaline compounds to displace soil rather than
dissolving it in an organic solvent.  Aqueous cleaning has been found to be a
viable substitute for many metal finishing operations currently using solvents.
Alkaline and acidic cleaners are applied using soak cleaning, spraying,
ultrasonic cleaning, electrocleaning, and steam cleaning.  The principal
advantages of aqueous-based cleaning are the ease of treating spent solutions
by pH adjustment and generally good biodegradability of organic detergents
used in alkaline baths.  Its principal disadvantage is that the workpieces are wet
after cleaning and ferrous parts easily rust under these conditions unless they
are dried rapidly. A common technique to accomplish this is hot water rinsing,
but this is a more costly alternative. Another disadvantage associated with
aqueous-based cleaning is an increase in the chemical oxygen demand (COD)
of the wastewater and wastewater treatment costs.  Mild steels are difficult to
clean effectively in an aqueous process.

About half of the approximately 100 million tons of steel produced in  the U.S.'
every year is treated in acid pickling baths. In this process sulfuric acid
     (H2SO4) or hydrochloric acid (HCI) is used to  remove scale from the
     surface of the raw ingot, sheet, or rod.  Acidic cleaning solutions may
      contain other mineral acids such as nitric or phosphoric; organic acids
      such as acetic, citric, oxalic, or sulfamic; detergents; chelating  agents; and
    possibly small amounts of solvents. This process removes up to 1.5
      percent of the metal and dissolves it in a pickling liquor (the acid with the
      dissolved scale). As the iron content of the bath increases, the pickling
      efficiency of the bath decreases to the point where new acid must be
    added or the dissolved iron must be removed.  When the steel is rinsed,   .
residual acid and dissolved metal are "dragged out" into the rinse water, creating
another waste stream. Three waste streams are created by the pickling
process:  spent pickling liquor, rinse water and metal sludge from acid recovery.

Alkaline cleaning solutions (usually run hot) are comprised of builders and
surfactants.  Builders usually consist of sodium salts of phosphate (PO4),
carbonate (CO3), silicate (SiO4) and hydroxide (OH ). Their function is to
promote chemical reactions which will remove the  metal oxides from the surface
of the workpiece.  Surfactants are detergents and soaps that tie up the metal
 oxide, and cause it to remain in the solution and not recombine with the metal
 surface.  Other additives are often used in conjunction with builders  and
 surfactants to act as anti-oxidants and stabilizers.  Some shops use an
 electrolytic cleaning method. All methods require a final  rinse step after
 cleaning.

 ABRASIVE AND THERMAL METHODS
 Mechanical means of cleaning can be an effective alternative to aqueous
 cleaning. Abrasives can be used in tumbling barrels or applied to buffing wheels.
 Abrasive blast cleaning methods use plastic, ceramic, or sand blast media to
 clean and strip parts.  The blast media can be recycled, thereby reducing
 disposal costs. Acid oc alkaline cleaners are sometimes added to form abrasive
 slurries in order to improve cleaning action. These slurries are discharged after
  a set period of use, but require controls for total dissolved solids (TDS) in the
 wastewater. .     .        '
                                    WASTE MIN1MIZAT10N IN THE METAL FINISHING INDUSTRY.

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   Heat or flame cleaning/stripping ovens offer another method of removing
   paint and other organic soils fronf workpieces by burning them off. The
   disadvantages of heat cleaning are high energy requirements, and the
   production of combustion emissions, which require control devices. Refer to
   Table 1 for a summary of primary cleaning processes.
            Table 1 - PRIMARY METAL CLEANING PROCESSES
PROCESS ,
Solvent cleaning .
'Aqueous-based
cleaning -
\s - ' ••
Abrasive- . ' '
Thermal cleaning

MATERIALS
1.1.1- •'
Trichloroethane
methanol, &
acetone
Detergents; caustic
& acidic
compounds
(NaOH, H2SO4)
Grit, sand, ceramic
and plastic media;
Heat

HOW USED
Vapor degreasing,
immersion, wiping
Heated tanks,
spraying, steam
cleaning, &
ultrasonic cleaning
Grinding, tumbling,
blast cabinets;
Burn*off ovens
"/x
DISADVANTAGES
High material
costs; worker
exposures & ,
flammability
High COD &TDS
in wastewater;
creates metal
sludges '
High capital costs,
APC equipment
required
High energy costs,
APG equipment
required ,
" • "•-
DESCRIPTION OF METAL F/N/SH/NC SYSTEMS

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Illllillllllllllillll!!!!
   Modifying
   the metal's
    •   surface
                  SURFACE TREATMENT AND PLATING
Surface treatment and plating operations are typically batch processes in which
metal workpieces are dipped into and then removed from baths containing
various reagents. The reagents are specially formulated to achieve the required
surface condition. The workpieces can be carried on racks or in barrels that
rotate in the plating bath.

Most surface treating and plating processes consist of three steps. The first is
cleaning or preparation of the surface, which has already been described. The
second step is the actual modification of surface itself, which  involves some
change in the properties of the surface. The final step is the rinsing of the
workpiece.  Metal-bearing waste is generated from alt three of these processes.
Four surface modification processes are listed below in Table 2.
                                 Table 2 - PRIMARY SURFACE TREATMENTS
                    PROCESS
                                             DESCRIPTION
                                                                     CHEMICALS USED
                    Chemical &
                    electrochemical
                    conversion
                         Deposition of a metal
                         oxide coating, for
                         corrosion resistance
                         and primarily to form an
                         absorptive base for the
                         adhesion of paints, etc.
Phosphates, chromates,
nitric acid, hydrochloric
acid, and metal coloring
                    Electroplating &
                    related processes
                    Metallic coatings
                         Workpiece acts as an
                         anode or a cathode in a
                         galvanic cell. Metal
                         ions are either attracted
                         to the part and plate
                         out, or are removed for
                         a high shine.
                         Dipping the core piece
                         into molten metal;
                         through vapor
                         deposition and vacuum'
                         coating
Brass, bronze,
cadmium, chromium,
copper, iron, nickel, tin,
zinc and precious
metals
                                                                     Aluminum, tin and zinc
                     Case hardening
                          Produces a hard
                          surface over a soft core
                          metal by chemical
                          diffusion or rapid heat
                          application
 Carbon (carburizing),
 nitrogen (nitriding),
 (using a salt bath of
 sodium and potassium
 cyanide)
  8
                                                       WASTE MINIMIZATION IN THE MfTAL FIN/SHINC INDUSTRY

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 rHFMICALAMD FT.ECTROCHEMICAI  CONVERSION
 Chemical and electrochemical conversion treatments include phosphating,
 chromating, anodizing, passivation, and metal coloring.  These treatments
 deposit a metal oxide coating on the metal surface, which is primarily
 intended to form an absorptive base for the adhesion of paints, lacquers,
 and oils applied in subsequent processes, the cpatings also impart some
 corrosion resistance to the surface. See Figures 1 and 2 for illustrations of
 chromating of aluminum and steel passivation.
                         PART
                                      ALKALINE CLEANER
                                      HEATED 120-laO-F
                                      WATER RINSE
                                      UNHEATED
                                      ACIOOESMUTTEH
                                      UNHEATEO
                                    •  WATER RINSE
                                      UNHEATEO
                                      IRFSOITE P90CESS
                                      UNHEATEO
                                      RINSE WATER
                                      HEATED 12O-180-F
                      ALUMIN01* SURFACE PHEP/UUTON-DIP TANK ONE


                                  nCUREl
                      A

                   WATER
.  .   -   B ' '

NITRIC ACID/WATER
'   C

 WATER:
                  STAINLESS STEEL SURFACE PREPARATION (PASSIVATION)
                  DIP TANK LINE
                                   Figure 2   x
DESCRIPTION OF METAL FINISHING SYSTEMS,

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            EKevolyt*
ELECTROPLATING AND RELATED PROCESSES
in electroplating, a workpiece is the equivalent of a cathode in a galvanic cell.  It
is placed in a solution of the dissolved metal to be plated.  The electric potential
applied across the cell is sufficient to attract the metal ions to the cathodic
workpiece where they are reduced on the surface. Metals which are commonly
electroplated onto workpieces are brass, bronze, cadmium, chromium, copper,
iron, nickel, tin, zinc and precious metals such as gold, platinum and silver.

In electropolishing, the workpiece acts as the  anode.  Surface metal is then
oxidized and dissolved in the bath solution. High points on the metal surface
dissolve faster than recessed areas. The result is a brightly polished surface.

METALLIC COATINGS

There are several nonelectrical techniques for applying a metal to a core of
another metal. Frequently, aluminum, tin, or zinc is applied by dipping the core
piece into a molten bath of the coating material. The high heat condition results
in coating adherence through a lattice interdiffusion of the two metals.  Cladding
techniques bond the coated metal through high pressure,  welding, or casting.
Other techniques include vapor deposition and vacuum coating.  See Figure 3
for a graphic showing vapor deposition of aluminum.

CASE HARDENING
This process produces a hard surface over a relatively soft metal core.  The
processes harden the surface through diffusion of carbon  (carburizing). nitrogen
(nitriding), or carbon and nitrogen (carbonitriding) into the  steel surface.
Nitriding involves the use of ammonia or a salt bath comprised largely of sodium
cyanide and potassium cyanide. Alternatively, nonchemical processes achieve
case hardening through very rapid heat application, which acts on the carbon
already present within the workpiece.
              Substrate
                 Holder
               Cathode
                                                                            Evaporator
                                                                            Power
                                                                            Supply
                           High Voltage
                           Power Supply
                         Aluminum
                         Evaporators


                        "\
                                                              Vacuum
                                                              Chamber
                                  A Vapor Deposition of Aluminum
                                                Figure 3
 10
                                WASTr, MfNlM17.ATKW IN THE METAl: F/N/SH/NC INDUSTRY

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a
an
                                         a
 PRINTED CIRCUIT BOARD MANUFACTURING
   Many aspects of printed circuit board manufacturing are very similar to
   processes used in electroplating.  The circuit board consists of a   x
   nonoonductive material laminated with copper foil.  Holes are then drilled
   and deburred to allow for wiring and electrical component connection. The
   board is then plated with electroless copper to approximately seventy
   millionths (0.000070) of an inch thickness. This serves as the base for
   electrolytic copper which is plated to an approximate thickness of one
   thousandth (0.001) of an inch, or one mil. Then gold, lead, nickel or tin is
   •electroplated, followed by the etching of the circuit pattern onto the board.

    Chemicals used in the manufacture of printed circuit boards include chromic
 •   acid  cupric chloride, and ferrous chloride for etching; stannpus tin
    compounds and palladium chloride for catalysts; copper sulfate for
    electroless plating; copper pyrophosphate, acid-copper sulfate. ac'dcopper
    fluoroborate, tin-lead, gold and nickel solutions for electroplating; and suKunc
    dichromate for resist stripping. Refer to Table 3 for a list of materials and
    their components.      -
Table 3'- CHEMICALS USED IN THE MANUFACTURE OF PRINTED CIRCUIT BOARDS
      Product/Process                         Raw Material
an
                                                  aai
gL
a  aaa
  .Board materials
   Cleaners
   Etchants
   Catalysts
   Electroless copper bath
   Screen v
   Screen Ink

   Resists
    Sensitlzers
    Resist solvents
    Electroplating
     Resist stripping
glass-epoxy. ceramics, plastic, phenolic paper,
copper foil
sulfuric acid, fluoroacetic acid, hydrofluoric acid,
sodium  hydroxide, potassium-hydroxide,
trichloroethylene, 1.1.1-trichloroethane.
perchldroethylene, methylene chloride
sulfuric and chromic acid, ammonium persulfate,
hydrogen peroxide, cupric chloride, ferric
chloride, alkaline ammonia
                                   stannous chloride, palladium chloride
 copper sulfate, sodium carbonate, sodium
 gluconate; Rochelle salts, sodium hydroxide,
 formaldehyde           '    • :    '
 silk polyester, stainless steel composed of oil,
 cellulose, asphalt, vinyl or other resins
 polyvinyl cinnamate, ally! ester, resins,
 isoprenoid resins, methacrylate derivatives.
 polyolefin sulfones
 thiazolirie compounds, azido compounds, mtro
 compounds, nitro aniline derivatives, anthones.
 quinones, diphenyts, azides. xanthone. benzil
 ortho-xylene, meta-xylene, para-xylene,     _
 toluene, benzene, chlorobenzene, cellosolve and
 cellosolve acetate, butyl acetate, 1,1.1.-
 trichloroethane. acetone, methyl ethyl ketone,
 methyl isobutyl ketone.

 copper pyrophosophate solution, acid-copper
 sulfate-solution, acid-copper fluorobate solution,
 tin-lead, go^ld. and nickel plating solutions
  suituric-drchromate, ammoniacal hydrogen
  peroxide, solutions methachlorpperbenzpic.acid,
  methylene chloride, methyl alcohol, furfural,
  phenol, ketones. chlorinated hydrocarbons, non-
  chlorinated organic solvents, sodium hydroxide
   DESCRIPTION OF METAL F/N/SH/NG SYSTEMS
                                                                                            11

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•JJ2                                                          WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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 This chapter will:
         Outline source reduction techniques used in:
           metal cleaning and stripping
           surface plating and related processes
           printed circuit board manufacturing

         Outline recycling and recovery processes used in:
           metal cleaning and stripping
           surface plating and related processes
           printed circuit board manufacturing
Chapter 2                                               ,
WASTE MINIMIZATION OPTIONS  FOR
THE METAL FINISHING INDUSTRY
                                                                       Least Desirable
  SOURCE REDUCTION IN CLEANING
       AND STRIPPING
     If workpieces must be cleaned, the least hazardous material
   .  should be considered first. Ideally, the cleaning method of choice
     would involve the fewest number of steps, employ the the least
     toxic medium, and generate the least waste. The most desirable
     cleaning media are air and water/ If these are not effective,
     abrasive media with air or water as carriers are the next most
     desirable. These may be applied by either hand wiping or with a
     blast-type device that uses pressure.                 -

     If chemicals are required to achieve the necessary finish, they should be
     tried in the following order: aqueous detergent solutions, alkaline solutions,
     acids, and solvents.  This hierarchy is based on the hazardous properties of
     the options and treatment costs. Many aqueous .detergents can be
     discharged directly to a POTW without treatment.  Effluent containing
     aqueous detergents will often meet POTW discharge requirements without
     additional treatment unless metal contamination is excessive. When
     treatment is required, it is usually for total dissolved solids (TDS) or chemical
     oxygen demand (COD).  Alkaline solutions typically require only pH
     adjustment before discharge,. Acid solutions can have considerable metal
     content and must therefore be treated more extensively. Solvents present'a
      number of problems, including their flammability hazard and health risks to
     workers. Before a shop changes from one cleaning  process to another it
      should fully evaluate the effects of the new cleaner, such as the effect of g
      substitute cleaner's surface residue or drag-out, on downstream processes.
      The shop should also check with its local air district to make sure that this
      use of the splvent is permissible. -      .

      PREVENTING THE NEED FOR CLEXNING
      The first step in implementing this very desirable option is to identify the type
      of surface soil. A wide variety of materials is used in order to facilitate the
      cutting, grinding, and drawing  of metal parts. These include mineral oils,
   Solvent
    Acid
   Alkaline
  Detergents
  Abrasives
  Air & Water
Most Desirable
  WASTE MINIMIZATION OPTIONS FOR THE METAL FINISHING INDUSTRY
                                                                                       13

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iliillillllillilillilllll
      Substitute
 non-hazardous
        coatings
       Substitute
         alkaline
         cleaners
    Extending the
      useful life of
      the cleaning
    solution bath
talc, graphite, chlorinated synthetic oils, and metallic soaps. Workpieces may
also be coated with water scale, heavy metal salts, or simply covered with
rust. Metal finishers should be encouraged to explore other fess hazardous
materials to facilitate these operations.

Metal finishers should be encouraged, to establish a "just' in time" approach to
manufacturing, where parts are cleaned in batches ho larger than can be
immediately fed into subsequent processes.  This eliminates the need to
warehouse parts between operations, during which they may contact new
contaminants and need to be cleaned again.  If cleaned parts must be stored,
dry nitrogen bagging is a proven way to keep parts clean and free of oxidation
as they are stored for subsequent coating.

Some coatings are applied by vendors supplying the workpieces to the metal
finisher  These coatings are intended to protect the material, bufthey simply
add another waste stream when they  have to be removed. The metal finisher
should work with the vendor to  replace the coating with a nonhazardous peel
coating or shrink wrapping with polymeric sheeting.

 It should be emphasized, however, that although the avoidance option should
 be examined first, unwarranted relaxation of cleaning requirements may have
 an opposite effect of increasing waste generated due to rework of rejects
 caused by poor coating.

 SOLVENT SOURCE REDUCTION
 Halogenated compounds are the. solvents typically used in cleaning
 operations' These compounds are known to pose significant environmental
 health hazards and should be used' only when an alternative aqueous-based
 emulsion, or mechanical cleaning method is not feasible.  If non-solvent
 cleaning is not possible, the use of alternative, less hazardous solvents such
 as terpenes, N-methyl-2-pyrrolidone, or dibasic acid esters should be
 considered.

 The use of hot alkaline cleaners can  prove a viable substitute for solvent
 degreasing. The purchase price for alkaline cleaners can be as little as half
 that of solvents.  Treatment and disposal costs are also generally lower for
 alkaline cleaners: Some need only pH adjustment before discharging to a
 publically-owned treatment works (POTW). Others may require treatment for
  excessive TDS or COD. Other alternatives to solvent cleaning are discussed
  below, with the emphasis on minimizing their waste output.

              -RASra WASTES
  While aqueous-based cleaning methods are superior to solvents,
  consideration should first be given to the use of water, steam, or abrasives as
  substitutes for acid or alkaline cleaners.  If their use is not feasible, then work
  with the shop operator to evaluate each aqueous-based cleaner with an eye
  toward selecting the cleaner that is least hazardous to workers and the •
  environment.        .     •
  Regardless of the aqueous-based cleaning method selected, a key to
  achieving waste minimization goals is to. extend the useful lifetime of the
  cleaning solution bath. It & critical to ensure that workpieces entenng the
  cleaning solution are as free of oils, solvents, or other cleaners as possible  A
  hot water bath for precteaning may be desirable.  The bath should be supplied
   14
                                                        WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

-------
  with demineralized water, possibly from the last rinse bath of the cleaning
 .operation.      .  ,            ;   '            '  :  ,-,   ,-/

  The accumulation of metal fines and paint chips is detrimental to aqueous-
  based cleaning solutions. Continuous filtering or regular sludge removal
  should be used to prolong the useful life of the solution. Tanks should have
  plastic liners or be coated with protective finishing to eliminate the entrance
  of impurities from the tank itself into the cleaning solution. The racks and
  barrels used to hold the workpieces should be corrosion-free so that rust is
  not added to the cleaning solution and excess drag-ouHrom solution
  adherence to roughened surfaces can be avoided.              '

  Float valves, while important to maintaining the proper level in the tank,
  should be closely monitored to ensure that leaks are not diluting the bath.

 . The  effectiveness of alkaline cleaner baths is reduced by introduction of
  materials that reduce the alkalinity, including the target soil. Bath life can be
  enhanced by avoiding unnecessary loading with .hard water or carbon
  dioxide in the air used for agitating the tank. Mechanical agitation and the
  use  of softened or deionized water are solutions to these problems. The
  operator should also consider keeping the tank heated continuously to
  minimize the absorption of carbon dioxide, with occasional cooling to allow
  for oil removal.               .                 „  .-

   ABRASIVES SOURCE REDUCTION
   Oil-based binders can burn due to the heat of friction generated during
   buffing  This results in the need for additional cleaning to remove the
   burned-on  oil. As an alternative, greaseless compounds, if used properly,
   will  result in parts which are clean and dry after buffing.  These greaseless,
   buffing compounds also prolong wheel life by adhering to the surface of the;
   wheel.

   The technique used for applying liquid spray abrasives to the buffing wheel
   can make  a significant difference in waste generation.  Too little will result in
   excessive  wheel wear, while over-application will produce waste compound
   and create the need for further cleaning of the workpiece. The use of a
   spray gun  for applying liquid abrasive spray has proven to be the most
   effective technique-in controlling the application rate.

    Maintaining the proper water level in mass cleaning operations is critical to
    source reduction.  If not enough water is used, parts will leave the solution
    dirty. Excessive water flow will increase the attrition rate of the abrasive and
    increase replacement frequency.     ,              ;
Using
greaseless
buffing
compounds
  SOURCE REDUCTION IN SURFACE PLATING AND
  RELATED PROCESSES
    There are significant opportunities for waste reduction by metal finishers.
    When changes are first suggested the inspector may encounter resistance to
    change by some metal finishers. "If it's not Brpken, why fix it", can be a
    common response from them when aiternative'chemistries or operating
    procedures are suggested. Witlvwaste disposal costs skyrocketing it may
WASTE MINIMIZATION OPTIONS FOR THE METAL FINISHING INDUSTRY
                                                                                          15

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  Change to
         less
  hazardous
   processes
be just such an attitude that results in going broke. The primary goal is to
challenge the metal finisher to initiate a review of his operation.  Success stories
of others can be extremely helpful. The bibliography contains references for
numerous case studies.

PROCESS SUBSTITUTION
Plating operations are inherently more dangerous to the environment than many
other metal coating techniques.  It is not likely that the inspector will get involved
in rethinking the entire process used by a finishing shop, but one should
generally be aware of potential process substitutions such as buffing, cladding,
and electroless coating, some of which were introduced in the previous section
titled "metallic coatings". Also, some accepted material substitutions to reduce
or eliminate the toxicity of the waste are referred to in Table 4.

MATERIAL PURCHASE. STORAGE- AND HANDLING
Proper control over the chemicals used in the finishing process is an important
way to reduce waste generation. This can be accomplished by establishing
material purchase and control procedures.  As one of the first steps in an
inspection,  the inspector should determine the extent to which the metal finisher
has established procedures relating to the purchase of chemicals. For instance,
it is important that all material  purchases be reviewed" by a key individual or
group within the operation prior to purchase. The approval process should
determine if the materials being evaluated contain hazardous constituents. If
so. the cost of treating and disposing of the waste generated s.hould be
determined and added to the cost of purchase.  This will help the facility to
evaluate the total costs of purchasing a chemical before the purchase is made.
Many substitute materials may have a higher purchase price than presently
used materials, but disposal and treatment costs may be lower.  The inspector
should encourage the metal finishing facility to use a "cradle to grave"
philosophy when evaluating the purchase of all materials.

Avoiding Material Degradation
Hazardous materials that have deteriorated due to prolonged storage or
materials held beyond their shelf life must be managed as hazardous wastes.
You should encourage metal finishers to review their inventory and material
usage policies of the finisher.  Suggestions may include strict tracking of
inventories, minimizing the volume of materials  in inventory, and adopting a first-
in first-out  material usage policy.                       ,-           .

 Limiting employee access to raw materials is likely to reduce careless waste.
The assignment of responsibility for mixing Chemicals for process baths to a
 limited number of employees will ensure batch consistency, thereby reducing
 waste.

 Managing Samples
 The metal finisher should ask chemicalsuppliers for small samples of less
 hazardous replacement chemicals. The metal finisher should also arrange.in
 advance with the chemical supplier to return the unused portion of the sample,
 since it must be managechas a hazardous waste. A bench scale test of the
 sample may be run to determine the quality of the final finish before any large
  scale tests are run. Many-alternative products  may need to be tested before an
  adequate replacement  is found. Bench scale tests make the screening process
16
                                   WASTE M/N/M/Z/mO.V IN THE METAL FJN/SH/NC INDUSTRY

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                Table 4 - CHEMICAL SUBSTITUTES









POLLUTING
Fire Dip (NaCN)
Heavy Copper Cyanide
Plating Bath
Chromic Acid PickleSi
Deoxidizers, & Bright
Dips
"Chrome-Based
Anti-Tarnish
"Cyanide Cleaner
Tin Cyanide
Plating with Chromic
Acid
Hydrofluoric Acid in . ;
Pickling and Stripping
SMBSTITUTE
Muriatic Acid with
additives
Copper Sulfate
.- S '
/ ,
Sulfuric Acid and
Hydrogen Peroxide
Benzotriazole (0.1-i.0%
olution in methanol) or
water-based proprietaries
Trisodium-Phosphate or
Ammonia
Acid Tin Chloride
Plating with trivalent
chromium, or bright nicke
Proprietary Fluoride Salts
COMMlNTS
Slower acting than +^2^2
traditional fire dip.
Excellent throwing power
with a bright, smooth,
rapid finish. A copper
cyanide strike may still be
necessary for steel, zinc,
or tin-lead base metals.
Requires good pre-plate
cleaning. Noncyanide
process eliminates
carbonate buildup in
tanks.
Nonchrpme substitute,
Nonfumjng.
Nonchrome substitute.
Extremely reactive,
requires ventilation.
Noncyanide cleaner.
Gooti degreasing when
not and in an ultrasonic
bath. Highly basic. May
complex with soluble
metals if used as an
intermediate rinse
between plating baths
where metal ion may be
dragged into the cleaner
and cause waste water
treatment problems.
Works faster and better
that the polluting
chemical.
Reduces worker
exposures to more
hazardous hexavalent .
chromium.
Reduces worker, hazards









WASTE MINIMIZATION OPTIONS FOR THE MEWL FINISHING INDUSTRY
                                                                                       17

-------
                   much easier and less expensive.  Plus, valuable production time is not lost and
                   large numbers of workpieces can be reworked if the candidate chemistry does
                   not produce acceptable results.

                   Spills
                   The best way to reduce spill-generated wastes is for the shop to have a training
                   program for personnel in proper handling of materials and appropriate
                   procedures for handling spills. Simple techniques such as the use of spouts,
                   funnels, and drip pans during material transfer can have a significant cumulative
                   impact,  Shops can place "collars" or drainboards that direct drainage back into
                   the process bath to eliminate spills to the floor. Providing adequate freeboard,
                   the distance between the top of the tank and the liquid level in the  tank, can
                   reduce overflows in process tanks. Liquid spills may be best cleaned up
                   through use of a mop and wringer rather than being soaked up with an
                   absorbent, which must then be transferred off site for treatment or disposal.
                   However, spills must be compatible with the mop, and mop and  other clean-up
                   tools must be kept segregated. Spill containment berms should also be
                   suggested for areas of high spill probability.

                   Spills resulting from equipment failure can be prevented through strict
                   adherence to preventive maintenance programs.

                   Residues and Empty Containers
                   Controlling  access to  raw materials and instituting a check-in procedure for
                   empty containers will  result in the complete use of one container of a chemical
                   prior to the opening of another. In this manner residues will be minimized and
                   container rinsing, if appropriate, will be ensured. Otherwise, empty containers
                   can be readily gathered for return to the manufacturer, avoiding  their accidental,
                   and possibly illegal, deposit into the solid waste receptacle. Unfortunately, many
                   suppliers will not take containers back.  Try to get a commitment from suppliers
                   to take empty containers back before purchasing.-

                   Inspections
                   Successful implementation of the suggestions in this section depends upon,
                   close monitoring by the shop manager. A key element in this monitoring is a
                   regularly scheduled inspection.program. The-inspection should  include
                   examination of all equipment, piping, chemical storage areas, chemical
                   containers and labels, training records, and chemical inventory records.

                   PROCESS BATHS

                   Material  Substitution
                   Chemical chelators are used in many processes to increase the solubility of
                   metals in the bath. Included in this class of compounds are organic acids such
                   as citric acid, maleic acid and oxalic acids and amines, such as  EDTA.  In
                   alkaline solutions these chemicals have a strong affinity for metal  ions  and they
                   are able to support higher concentrations of metals in solution.  The problem
                   with these chemistries is the large volume of sludge produced when they are
                   treated. The first step in the treatment of chelated process chemistries is to
                   adjust the pH to between 3 and 5. This inactivates the chelators so the metal
                   ions may be precipitated.  This is generally done by adding ferric sulfate in a
18
WASTE MINIMIZATION IN THE METALflNISHINC INDUSTRY

-------
 ratio of up to eight to one by weight to the contaminating metal. The volume
 of sludge generated is thus increased eight-fold over that of the contaminant
 •alone.                            -    "   '.                   •.  . .
 Non^helated chemistries are an alternative you might suggest to the metal ,
 finisher  The cost of these non-chelated materials is slightly higher than' the
 cheiated alternative, but the sludge volume generated is significantly lower
 The non-chelated chemistry usually requires continuous filtration, which will
 cost between $400 to $1000 per tank, plus filter replacements and
  maintenance costs. For this modest investment the metal finisher will
  reduce waste and lower treatment costs, and the treated effluent is  more   ;
  likely to meet POTW discharge requirements-.

  The health risks of hexavalent chromium are well documented. Its treatment
  as a waste requires the addition of sodium metabisulfite to reduce it to the
  trivalent state.  Cost savings have been demonstrated through the direct
  plating of trivalent chromium. This process has proven especially viable for
  decorative chrome plating. The most significant drawback to this system is
  that the plated pieces tend to have a darker and less shiny appearance than
  hexavalent plated pieces.  On balance, though, the disadvantages of this
  substitution are outweighed by the advantages which include decreased
  liability, lower disposal costs and increased worker safety.

  One of the most hazardous materials used by the metal finishing industry is
  cyanide. Inspectors finding this material in general use should suggest that
 - alternative chemistries be sought by the facility. When disposal of the
  cyanide-bearing baths is necessary, they are usually treated by alkaline
  chlorination using hypochlorite salts or chlorine gas. If complex cyanides are
  being treated, ferric sulfide must be used for precipitation with the previously
  mentioned large volume of sludge being generated. Refer to Table 4 for
  alternatives to hexavalent chromium and cyanides.    >

   Successfurnon-cyanide plating of zinc and copper has been demonstrated.
   Research is focusing on the development of a practical non-cyanide
   cadmium plating process. Economic incentives can make the change to
  ' non-cyanide chemistries extremely attractive to a metal finisher.  A two
   gallon per minute rinse water flow containing cyanide can require as much
   as $12,000 in treatment equipment and $3.00 per.pound in treatment
  • chemicals.      .     '     „   ,  •          ,

   Extending Solution Life           ..'       ,
   Metal finishers should also consider methods of extending the life  of process
   baths as a waste reduction strategy.  The longer a bath can be used, the
    lower annual treatment and disposal costs will be, Deionized make.-up water
    should always be. used in process tanks and rinse systems.  The carbonate
    and phosphate present in tap water reduce the efficiency of rinsing
    operations and reduce the life of process baths.  The solids in tap water also
    increase the amount of hazardous sludge created. Deionizatton systems
    consist of a series of steel tanks containing a mixed bed of resins. These
    resins have active sites on their surfaces,'which have affinities for either
    negatively charged anions or positively charged cations. As the tap water is
    passed through the resins, ionic compounds  are adsorbed by the resins,
    thereby purifying the supply water. The cost for installation and rent of a
Using
de-ionized
make-up
water
WASTE MINIMIZATION OPTIONS FOR.THE METAL FINISHING INDUSTRY
                                                                                           19

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tiiiiiiiiiiiiiiiiiiiiiiii
    Replenish
  baths rather
          than
      dumping
         "them
       Remove
 contaminants
    from baths
 deionization system will generally be offset by reduced costs resulting from
 longer rinse bath lives.
 One problem commonly found in alkaline baths is the build-up of carbonate
 salts  These come from the dissolution of atmospheric carbon dioxide in the
 baths Accumulated salts, as well as other cleaning and etchant compounds,
 can interfere with the efficiency of the process bath and reduce-rts useful life
 Removal of these precipitates using continuous filtration can extend the useful
 life of the bath and thereby reduce the waste produced annually from that
 process.
 Process baths are depleted in a number of ways. Chemicals essential to the
 process are removed as drag-out coating workpieces; water evaporates from
' the bath and contaminating chemicals are introduced when workpieces are not
 completely rinsed.. Replenishing the bath is one option the metal finisher should
 consider before dumping the  bath.  This requires some simple monitoring
 practices such as routine measurement of pH and metals concentration.  When
 the effectiveness of the bath falls off, part of the bath can be dumped and fresh
 water and chemicals can be added to  replace what has been lost.

 The introduction of contaminants cannot be controlled by simply adding more
 water and chemicals.  Eventually, the  levels of contaminants will increase to the
 point where process efficiency will begin to be affected.  It is at this point that the
 finisher should be encouraged to seek out a treatment process that can extend
 the life of the bath.  For example, copper can contaminate zinc and nickel
 plating baths. When this happens some platers will use a treatment process
 called electrolytic dummying. This process relies on the fact that the
 contaminant copper, has a lower electrolytic potential than the zinc or nickel in
 the process bath. 'An electrolytic plate is placed in the bath and a very low
 current is applied to it. Since the copper requires less electric potential to be
  reduced it plates out preferentially on the panel. It can take several days to
  reduce the copper contaminant to-acceptable levels, but the trade-off is the
  extension of the bath's life and reduction in waste generation.
          1 ',",''.             ,     '     ,        .       '      '
  in another example, the "plater may take advantage of the extreme insolubility of
  lead and cadmium sulfide salts. By simply adding ferric sulfide to the process
  bath and tittering the resultant precipitate from the bath, the bath life can be
  extended  In all cases, the inspector should encourage metal finishers.to use
  their special knowledge of their own processes to find new ways to extend the
  useful life of their process baths. Periodic laboratory-analysis of process tank
  contents will enhance understanding of the unique chemistries involved  and
  how to increase process solution life.
                                                     i       ,             •  •
  D,rag-Out Reduction
  Reduction of drag-out from  process baths is a key to reducing waste in the -
  metal finishing industry.  Drag-out occurs when process solutions adhere to
  workpieces and are carried into subsequent rinse tanks. The drag-out creates a
  waste stream that  must then be treated. Reducing drag-out can save in both   .
   reduced process chemical costs and waste disposal costs.

   The volume of drag-out is influenced by the size and shape of workpieces, the
 • viscosity of the process batr\and the concentration of the bath.

 .  Some workpieces have concave surfaces, which can trap considerable volumes
   20
                                                        4HSTE MljiHMK/TON IN THE MEWL HNEH/NG INDUSTRY-

-------
  of solution when they are withdrawn from a bath. The inspector should
  observe the procedures the operators are using when the racks containing
  the workpieces are removed from baths. Try:to determine if by simply
  turning, twisting or shaking the racks, additional drainage of process
  solution can be achieved. Also make certain that the time the racks
  are allowed to drain over the tank is sufficient. Some metal
  finishers have installed a rail over their process baths where
  operators can hang racks to increase the drainage time.  Also,
  observe the rate at which the racks are withdrawn.  The slower
  the rate of withdrawal, the thinner the film of drag-out on the
  . workpieces.                    •  '

  The higher the viscosity of the bath,.the thicker the film
  coating the workpieces will be.  There are several ways the
  metal finisher can reduce the viscosity and resultant drag-
  out. Reducing the chemical concentration in the bath will not
  only reduce viscosity, but also will reduce the costs of       -
  chemicals and of treatment when the bath is dumped.  The inspector should
  encourage the finisher to test tower chemical concentrations when process
  baths are formulated to determine if this option is viable. If product quality is
  reduced, the chemicals can be added in increments until the desired quality
  is achieved.  This may not be adoption if contractual specifications require a
  minimum bath concentration. ,          .      •'             :

  Another way to reduce the viscosity of  process solutions'^ to increase the  .
  temperature. While temperatures can  increase the effectiveness of some
   cleaning, it can also pose a greater risk to workers through higher emissions
   of toxic air contaminants, such as chromium and cyanide, and it will increase
   energy costs.

   When high temperature baths are used in conjunction with drag-out tanks,
   the benefits can be doubled. A drag-out tank is a tank placed next to a
   process bath and filled with deionized water. When the workpieces are
   .withdrawn from the process bath and drained, they are placed in the drag-
   out tank. The contents of the drag-out tank can eventually be used as make
   up for the process tank either after an  evaporation step is used to
   concentrate the drag out tank solution, or directly.  Drag-out tanks can
    reduce rinse water volumes and chemical costs by as much as 50%.

    Fog sprays and air knives are very useful in reducing dragrout. A spray of
    deionized water or air can return as much as 75% of the drag-out back to the
    process tank.  Fog sprays are typically located just above, the surface of the
    bath and work best where the rate of spray jnatches the rate of evaporation,
    from the tank. Air knives, also located just above the tank, reduce the drag-
    out by mechanically scouring the liquid adhering to the workpiece. However.
  •  when using compressor-supplied air, it is important to properly filter the air to
    prevent the contamination of the bath or .the part with oil;  Further, in some
    cases it may not be desirable for the workpiece to dry between process
    steps. Both of these very effective drag-out reduction techniques can be
    installed for about $500 per tank.

    The use of wetting agents can reduce drag-out by up to 50%.  The metal
    finisher should ask his chemical supplier if wetting agents are used in the
    chemistries being supplied and, if not, whether wetting agents can be added.
Allow longer
drainage

Use less
viscous baths
 Other methods
 for reducing
 drag-out
WASTE MINIMIZATION OPTIONS FOR THE METAL FINISHING INDUSTRY
                                                                                           21

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            Use
countercurrent
 rinse systems
 In some plating baths wetting agents'have been found to improve the quality of
 the finish as well as reduce drag-out.

 The manufacturers of the process chemicals may recommend concentrations
 greater than are necessary to do a quality job. Maintaining baths at the lowest
 acceptable concentrations will reduce the amount of drag-out. Fresh baths will
 function at lower concentrations which can then be increased during
 replenishment.
 The inspector should try to impress upon the metal finisher that these drag-out
 reduction measures, alone or in combination, are essential to an effective waste
 minimization program and may in fact result in significant reductions in water-
 usage and treatment costs.

                KTNSF SYSTEMS
                The focus of rinse system design and review is on the
                conservation of wastewater. If the shop has sufficient floor  .
                space, the installation of a multi-stage counter-current rinse.
                system can reduce water consumption up to 99%.  This system
                utilizes multiple rinse tanks, through which the workpiece is
                dipped in succession.  Fresh rinse water flows into the last of
                the tanks. Overflow from each rinse tank flows into the tank up
                the line, in the opposite direction of the movement of the
                workpiece. Effluent from the uppermost rinse tank is used as
       wat"     make-up water for the process tank or captured for recycling,
                resource recovery,  or treatment.,

  Whether or not multistage rinsing is used, spray rinsing prior to djp rinsing will
  significantly reduce drag-out, thereby allowing a reduction in the rinse tank(s)
  flow rate.                                  •
  Agitation of rinse tank water or of the racks holding the workpieces also
  increases the efficiency of the rinsing process.

  Pre-set block valves or valves with restrictive orifices can bq used to control
  water flow.

  IMPROVED HOI ISF.KEEPING
  Elimination of space between tanks or installation of drainboards to direct drag-
  out back into the tanks when moving workpieces from one tank to another will
  prevent drainage onto the floor, which would otherwise enter the floor drains
  during hose down operations.      .


SOURCE REDUCTION  IN  PRINTED CIRCUIT BOARD

MANUFACTURING
  Due to-the similarities of many of the processes used in surface plating and
  those used in printed circuit (PC) board manufacturing, this section focuses on
  those aspects of source reduction unique to PC board manufacturing. For
  additional information on^source reduction in cleaning and surface preparation,
v  electroplating and electroless-Rlating. and  rinse systems, refer to these sections
  in the prior discussion of surface plating and related processes.  Fable 5 lists
  chemicals and subsequent wastestreams  generated in the manufacture of PC
   boards.
   22
                                                        WASTt: MINIMI7AT10N IN'Tlir. MftAL fW/SWNC INDUSTRY

-------
                                  TableS
WASTE SOURCE
WASTE STREAM
DESCRIPTION
WASTE STREAM
COMPOSITION
Cleaning/Surface
preparation
1. Airborne
  particulates -
2. Acid fumes/organic
  vapors
3. Spent acid/alkaline
  solution
4. Spent halogenated
  solvents
5. Waste rinse water._
Board materials, sanding
materials, metals,
fluoride, acids,
halogenated solvents,
alkali.
 Catalyst application /
 Electroless plating
 1. Spent electfoless
   copper bath  ,
 2. Spent catalyst
   solution
 3. Spent acid solution
 4. Waste rinse water
Acids, stannic oxide;
palladium, complexed
metals, chelating agents.
 Pattern
 printing/masking
 1 .Spent developing
   solution
 2. Spent resist removal
 .  solution
 Vinyl polymers,
 chlorinated hydrocarbons,
 organic solvents, alkali.
,
Electroplating '
Etching
3. Spent acid solution
4. Waste rinse water
1 , Spent plating bath
2. Waste rinse water
1. Spent etchant
2. Waste rinse water
- -•
Copper, nickel, tin,
tin/lead, gold, fluoride,
cyanide, sulfate.
;
Ammonia, chromium,
copper, iron, acids.
 WASTE MINIMIZATION OPTIONS FOR THE METAL FINISHING INDUSTRY
                                                                                             23

-------
New products
         being
    developed
   Use aqueous
     resist and
 screen printer
PRODUCT SUBSTITUTION
The conventional method for attaching components to a circuit board requires
that there be holes in the board.  New developments in surface mount
technology allow for closer contact area of connected leads, thereby allowing a
reduction in board size to as little as thirty-five percent of the .conventional .
design.  As board sizes are decreased, waste generation is decreased
commensurately, with the exception of degreasing agents such as CFC-113
which are required in significantly greater quantities to adequately clean the
boards for surface mounting. When an appropriate substitute for the ozone-
depleting CFC-113 is identified, the relative environmental impacts of this
technology should be less than those of the traditional technology.

Battelle has developed a technique which couples injection molding of the board
with a fast-rate electrodeposition technique that is used to produce a complex
circuit board without the need for etchants, thereby reducing waste generation.

CLEANING AND SURFACE PREPARATION
While it is possible to use chelators in printed circuit board manufacturing
process solutions to increase the solubility of metal ions, this practice has been
curtailed due to tighter controls on wastewater. When used, this practice results
in the need for additional reducing agents, such as ferrous sulfate, which cause
the generation of significantly more sludge.  The use of non-chelate process
solutions or a mild chelator such as ethylenediaminetetraacetic acid (EDTA)
may be feasible. For etching, non-chelate etchants such as sodium
permanganate and hydrogen perdxide/sulfuric acid may be feasible, but their
use requires rigid controls. However, non-chelate process baths require
continuous filtration to control buildup of solids, a cost item the operator must
evaluate in comparison to waste management costs.

PATTERN PRINTING AND MASKING
The desired pattern on a circuit board is created by the application of a material
which resists plating. Such a material is called resist.  Conventionally used
 resist must be'processed and developed with organic solvents.  Aqueous
 processable resist is available which results in decreased waste generation.

 Screen-printing of circuit patterns instead of photolithography is recommended
 to eliminate the need for developers. New high-resolution screen-printing
 techniques have increased the potential applicability of this alternative
 approach.

 Etching
 The potential tor using thinner copper foil should be explored. This alternative
 reduces the copper load produced during the etching process.

 Explore the use of non-chelated etchants.  Sodium persulf ate and hydrogen
 peroxide/sulfuric acid are non-chelate mild etchants which can be used to .
 replace the chelate etchant, ammonium persutfate.

 The use of non-chromium etchants such as ferric chloride or ammonium
  oersultate will result in a less toxic waste.
                                              '•        •      •
   24
                                   WASTE MINIMIZATION IN THE MCTAL FINISHING INDUSTRY

-------
  Many manufacturers have switched to pattern instead of panel plating. This
  change reduces the amount of copper which must be etched away, thereby
  reducing waste volume and toxicity. This change is not possible in all
  instances, but should be encouraged wherever possible.

  Additive plating of boards, instead of the conventional subtractive method,
  eliminates the need for etchants. However, current additive techniques
  necessitate the use of solvent processable resists and the spent baths
  contain heavily complexed copper which may Complicate wastewater
  treatment.   •••.-.'             ;
RECYCLING AND RESOURCE RECOVERY IN

CLEANING AND STRIPPING
  Notwithstanding a significant effort in source reduction, most metal finishers
  will continue to generate waste. Many options exist for recovering valuable
  metals from these wastes. Any type of treatment process beyond simple
  neutralization or pH adjustment requires a treatment, storage or disposal
  (TSD) permit either under RCRA or California law. treatment activities not
  requiring a RCRA permit may be eligible for inclusion in California's permit
  by rule program which might be.exempt from permitting requirements.
  However  a permit by rule still involves agency and public-notifications and
-  financial assurance. The generator must check the recycling laws to ensure
  compliance before considering onsite or offsite recycling. The requirements
   for such an exemption are very specific and the determination is made on a
   case by case basis.

   SOLVENT RECYCLING

   If solvent use is unavoidable, the best waste management strategy to
   suggest is recycling with onsite distillation equipment.  This equipment can
   handle volumes as low as five'.gallons. If the plant operator does not want to
   purchase or lease onsite equipment, then offsite recycling should be the
   option of  the last resort. Care must be taken to avoid cross contamination of
   solvents.  Mixed solvents are difficult and, at times, impossible to recycle,   .
   and must be incinerated.                             -   '

   AQUEOUS-BASED CLEANFR RECYCLING
-  The prospect of recycling aqueous-based cleaners is enhanced through the
   use of non-emulsifying cleaners, which limit the separation of oil.

    Closed-loop systems have been demonstrated for acid pickle wastes.  Spent
    pickle liquor has recently been processed through a bipolar membrane,
    which results in a regenerated pickle liquor and a filtrate containing the
   • precipitated metals.  '                            .  - '            ,
Check the
regulation
  Still Bottom*
WASTE MINIMIZATION OPTIONS rOR THE METAL FINISHING INbUSTRY
                                                                                         25

-------
liiillillilllllllliiilill
                 RECYCLING AND RESOURCE RECOVERY IN
                 SURFACE PLATING AND RELATED PROCESSES

                   MATERIAL RECOVERY AND REUSE
                   As regulatory requirements for plating wastes have increased, previously
                   uneconomical recovery methods have become feasible, particularly for larger
                   facilities. While smaller facilities may not be able to implement these  ,
                   technologies onsite, they should be informed of their relative merits so thai: they
                   may make appropriate decisions regarding offsite treatment.

                   The technologies available are:  1) evaporation, 2) reverse osmosis, 3) ion
                   exchange, 4) electrolytic recovery, and 5) electrodialysis.

                   Evaporation
                   Evaporation is used to reduce the volume of a wastestream for subsequent
                   treatment or to concentrate a contaminant sufficiently for use as a feedstock.
                   Atmospheric evaporation systems cannot recover the vaporized water like
                   vacuum evaporation systems do, but are considerably less expensive- The
                   energy demand of evaporation systems  is their biggest drawback. See
                   Figure 4.

                   Reverse Osmosis
                   Reverse osmosis (RO) technology has long been used to recover plating
                   chemicals from rinsewater as well as to purify mixed wastewater for reuse.  It is
                   used most commonly to purify rinse water from acid nickel process baths.  The
                   water is returned to the rinse tank while the nickel salts are used to replenish the
                   plating tank. The method involves forcing metal laden water through a
                   semipermeable membrane under pressures of 200-to 1200 psi.  The membrane
                         Surface
                        Evaporation
                   .  ra
                              Drag-Out
                         Plating
                          Bath



i


f

m m

*
"T""-"*-N
' 1
t -
'

f m
<



1
••-•""•— ']
k

3-Stag« Countereuirent Riming
Used Rin«« Wat«r
                                         Concentrate
                    -Makeup
                     Water
                                                                   Condenaate
                                  EVAPORATION SYSTEM

                                          "*'**
                                      Figure*"^
 26
WASTr. MINIMIZATION IN THE METAL FINISHING INDUSTRY

-------
                                     3-Stag* Counwrcunvnt Rinsing
                                                         Slowdown lo
                                                        Wast* Treatment
                          REVERSE OSMOSIS SYSTEM  '

                                    " Figure 5
is impermeable to most dissolved solids. The operator must carefully
evaluate the type of membrane and module design to ensure that the unit
will perform adequately and will fit into the allotted space.  This method is not
suitable for compounds having a high oxidation potential (e.g., chromic acid)
and must be augmented with activated carbon treatment if non-ionized
organics are present. The. energy costs can be high because of the high
pressures required: See Figure 5.
Ion exchange
Ion exchange is also effective for recovery of drag-
out from rinse waters. The process exchanges ions
of harmless substances contained within the
exchange resin for the ionized metals in the rinse
water. The solid ion exchange particles in the resins
are either naturally occurring inorganic zeolites or.
the more commonly used synthetically produced
organic resins. This system is suitable for chromic
 acid rinses and is being usedto recover several
 metals (e.g. Ni, Cu, Ag) as. concentrated solutions to
 be returned to the process. However, rinse waters
 must be segregated to do this. This method is
 generally less delicate than reverse osmosis.  It can
 also be effective in removing/recovering aluminum,
 arsenic, cadmium, copper, and cyanide. On the
 other hand, ion exchange units require close-.
 monitoring and may add to the wastewater   x   ,
 treatment load due to large volumes of regenerant
 and wash solutions.                        "
 See Figure 6.
                                                           Influent Water. B+ Ions
                       Ion Exchange
                       Active Zone
           • '  Treated Water, A+ Ions
 Legend:   -
 B = B+ Ions
<3S>:= Resin Containing B+ ions
©= Resin Containing A+ Ions
 A = A+ Ions  .     '
                                                                                   , Figure 6
                                                                                         27

-------
                 Electrolytic Recovery

                 Electrolytic recovery captures metals in solution by plating them out on a thin
                 starter sheet made of the metal to be recovered or a stainless steel blank, which
                 serves as a cathode in the tank. The product of this process is a solid metallic
                 slab, which can be reclaimed or used as an anode in an electroplating tank.
                 The technology, also called electrowinning, is applicable to rinse water and
                 spent process baths. This technique requires rinse water segregation to
                 prevent contamination of the anode with mixed metals.

                 Electrodialysis
                 Electrodialysis uses selective membranes to separate anions and cations from
                 rinse waters. Each component can then be cycled back into the appropriate
                 tank. See Figure 7.

                 KTMSF WATER REUSE
                 Consider the potential of using rinse water following acid cleaning as makeup
                 water for rinse tanks following alkaline cleaning.  The method should prolong .the
                 life of the rinse water and will enhance rinsing of the alkaline-cleaned workpiece
                 by reducing the viscosity of the drag-out film. Workpiece quality specifications
                 will determine  whether this method of recycling will work since it results in salt
                 deposition (ie. spotting) on the part.

                  Final or critical rinse water may be clean enough for use as makeup water in
                  rinses requiring lesser effici&ncy.  {See discussion of rinse systems in source
                  reduction section.)
                RECYCLING AND RESOURCE RECOVERY IN
                PRINTED CIRCUIT BOARD MANUFACTURING
                  There are several opportunities for recovering metals from solutions involved   v
                  with printed circuit board manufacturing in addition to the methods previously
                  described for electroplating.                      ,

                  Copper from etching baths may be recovered and purified and used as makeup
                  for the electroplating baths.

                 . Cupric chloride etchant, reduced to cuprous chloride by the etched copper, may
                  be regenerated through direct chtorination. This is a new idea and the
                  equipment arid technology are not currently available.

                  Recovery of metallic forms of copper, lead, and tin has been demonstrated by
                  passing wastes through an exchange reactor containing aluminum, which
                  displaces the metals due to the higher oxidation potential of aluminum.
28
                                                    WASTF. MINIMI7AT10N IN THE METAL FINISHING INDUSTRY

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 Purified Stream
 (to rinse tanks)
                                                                 Concentrated
                                                                 Steam
                                                                 (to plating bath)
                                                                        Anode
                                                             Contaminated
                                                             Rinse Water
                 Legend:

                 M+ = Cations
                 X- = Anions
                 IXXXX1  Cation-selective membrane
                 K\\\j  Anion-selective membrane

                                 ELECTRODIALYSIS

                                      Figure 7
WASTE MINIMIZATION OPTIONS FOR THE METAL FINISHING INDUSTRY

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30
WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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Review Questions
     The Metal Finishing Industry
      1.   Is there such a thing as a "typical" metal-finishing shop? Briefly
          discuss the range of metal-finishing shops.     .

      2.   Why is it important .for the metal-finishing industry to reduce its
          waste streams?              •       .
     Physical and Chemical Processes
      3.  What are the primary metal cleaning processes? What are the
          advantages and disadvantages for each process?

      4.  Describe the following chemical and electrochemical processes:   ,
         ' Phosphating, chromating, anodizing, passivation and metal coloring.

      5.  What occurs during electroplating and electropolishing? How do they
          differ?          .    .        •     '                 '  . ••   '

      6..  How are metallic coatings placed on workpieces?

      7.  Describe case hardening^

      8.  List the steps in printed circuit board manufacturing.
     SourceReduction         •
      9.  What is the hierarchy in cleaning and stripping? What is the basis for
          this hierarchy?                                    -.-/'.

     10.  What alternatives can be implemented to reduce the need for cleaning?

     11.  Discuss substitutes for the following-

          Solvent cleaners                   ',-.'.                 : ,
          Alkaline/acid cleaners       ;  .
          Detergents                                           .''.".'.

     12.  Name the substitutes for both chromic acid brightener and cyanide,
          cleaner  ;                                     /-   ~ '

     13.  How can material purchasing, handling and.storage contribute to
          .source reduction?      ',         .             \ ;

     14.  What are some of the best ways to avoid or reduce spills?
                v            ;   ."•'"'•••.._    . .   •   •      i    .,  .
      15.  Discuss how frequent and regular inspections by facility personnel can
          minimize waste.
 REVIEW QUESTIONS
                                                                                          31

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                  16.   Review the following techniques for process bath source reduction:

                       material substitution
                       extending solution life
                       drag-out reduction
                       modified rinse systems
                       improved housekeeping

                  17.   Name three source reduction techniques for the printed circuit board
                       manufacturer.                            .
                  Recycling and Resource Recovery
                  18.  Discuss solvent and aqueous-based cleaner recycling.

                  19.  Describe how the following technologies are utilized for material recovery
                       and reuse:                      :

                       evaporation
                       reverse osmosis '                                      '
                       ion exchange
                       electrolytic  recovery
                       electrodialysis
                       rinse water reuse
32                   '                               WASTC MINIMIZATION IN THE METAL WISHING INDUSTRY

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REFERENCES

     Campbell, Monica E. and William M. Glenn. Profit from Pollution Prevention:
       A Guide to Industrial Waste Reduction & Recycling. Toronto, Ontario,
       Canada:  Pollution Probe Foundation.

     Guides to Pollution Prevention:  The Printed Circuit Board Manufacturing
       Industry.  U. S. Environmental Protection Agency (EPA/625/7-90/007),
       June,, 1990.

     Guidelines for Waste Reduction and Recycling: Metal Finishing.
       Electroplating, and Printed Circuit Board Manufacturing.  Oregon
       Department of Environmental Quality, hazardous Waste  Reduction
       Program, March, 1989.

     Hazardous Waste Fact Sheet for Minnesota Generators: Metal
       Manufacturing and Finishing. Minnesota Pollution Control Agency and
       Hennepin County Department of Environment and Energy, undated.

     Hazardous Waste Minimization Manual for Small Quantity Generators.
       University of Pittsburgh, Center for Hazardous Materials Research, 1989,

     Hazardous Waste Reduction Checklist & Assessment Manual for the Metal
       Finishing Industry. California Department of Health Services, TSCP/ATD,
       undated.

  .   Hunt, Gary E. "Waste Reduction in the Metal Finishing Industry". JAPCA. 38:
       672-680,1988,                                \

     Mehta, Suresh and Thomas Besore. Alternatives to Organic Solvents in
       Metal-Cleaning Operations. Illinois Hazardous Waste Research &
       Information'Center, July, 1989.                     '

     Metal Plating Industry Waste Reduction  Audits.  HMS' Environmental Inc. for
       Washington State Department of Ecology, Office of Waste Reduction,
     .  June,  1989.        ,..'    '            .  ' / '   ,    :

     Nunno, Thomas, Stephen Palmer, Mark Arienti, and Marc Breton. Waste
       Minimization in the Printed Circuit Board Industry—^ Case Studies.  U. S.
       Environmental Protection Agency (EPA/600/S2-88/008), March, 1988.

     Pollution Prevention Tips: Drag-Out Management for Electroplaters. North
       Carolina Department of Natural Resources & Community Development,
    •   1985.        . ,  :    ••;''-"•"'"•   ,/        •

     Pollution PrevehtionTips: Counter-Current Rinsing. North  Carolina
       Department of Natural Resources & Community  Development^ 1985.

     Pollution Prevention Tibs: Rinse Tank Design.  North Carolina Department
       of Natural Resources & Community Development, 1985.

     Pollution Prevention Tips: Rinse Water fleuse. North Carolina Department
       of Natural Resources & Community Development,  1985.

     Reducing California's Metal-Bearing Waste Streams.  Jacobs Engineering
       Qroup for California Department of Health Services; TSCD/ATS, August,
       1989.     .                .    .  '  "x.     '       .,
 REFERENCES                       ...      /  ..,   *             ,      .   .            .  .. ..   33

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                 .-               .   •   .            :	:	•   ,.
                 Reducing Hazardous Waste Generation with Examples from the Electroplating.
                   industry. North Carolina State University, School of Engineering, Industrial
                   Extension Service,  1985.

                 Rpdnrinn WaW Pollution ffrntml Costs in the Electroplating Industry.  U.S.
                   EnvironrnentalI Protection Agency (EPA/625/5-85/016), September. 1985.

                 Thibautt James "The Costs and Benefits of Source Reduction in Metal
                   pniehiAg- in Moptinn Ha7ardous Waste Requirements for MftTal Finishers
                   (Seminar Publication). U. S. Environmental Protection Agency (EPA/625/4r
                   87/018), September, 1987;

                 wast* Anriit Studv Metal Finishing Industry.  PRC Environmental _
                   Management, Inc. for California Department of Health Services, TSCD/ATS
                   and U. S. Environmental Protection  Agency, May, 1988.

                 waste Audit Study p"nted Cirrilit  Roard Manufacturers.  Planning Research
                   Corporation for California Department of Health Services, TSCD/ATS, June,
                    1987.
                 waste Minimization in M^i Parts Cleaning .  U. S. Environmental Protection
                   Agency (EPA/530-SW-89-049), 1989.

                          nirnirflti"" Audit Rsport: Ca*G Studies of Minimization of Cyanide
                          frnm HentnP18*'"" Operations. U. S. Environmental Protection
                    Agency (EPA/600/S2-87/056), January, 1988.

34
                                                    W/4STE MMIM17.ATION IN THE METAL F/N/SH/NG INDUSTRY

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 GLOSSARY

     Abrasive Blasting
        A method used to remove brittle material such as millscale oxide, remains
        of paint, etc.  More generally referred to as grit blasting.   ••'.'.

     Acid Descaling                                         >
   „     An alternative name for "pickling," a process using acid to dissolve oxide
        and. scale.          .   \

     Activation
        Process of removing last trace of oxide on a metal surface and a thin
        layer of the metalitself to ensure that the metal surface to be plated is
        eiectrochemically active, (see^etching")

     Alkaline Descaling .
        A chemical process for removing scale.  A typical descaling solution uses
        caustic soda with additives such as detergents and chelating agents.

     Alloying                 .
        The addition of one metal to. another metal or non-,metal or combinations
        of. metals.  For instance, steej is an alloy of iron and carbon.  Other metals
        are added to steels to impart specific Characteristics like strength or
        corrosion resistance.    .

   "Alochrom"                                 ."".",
        A proprietary process applied to aluminum and its alloys to improve
        corrosion resistance or to prepare surfaces for painting. Treatment
        produces an adherent aluminum oxide with some.absorfaed chromate.

     Amalgamating
        Process in which alloys are formed with mercury such as gold, silver, iron,
        copper and aluminum.  Due to the toxicity of mercury, use of the
        technique is declining.

     Annealing
        A heat treatment process which may be applied to all metals to soften
       them.   :.-...-•.

     Anodic Etching
        A form  of electrolytic etching where the workpiece being etched is anodic
        in the electrolytic circuit (in electroplating, the workpiece is the cathode).

     Anodizing
        A process generally applied to aluminum and its alloys to produce an
        adherent oxide film to impart corrosion resistance or surface hardness.
GLOSSARY   '             .           .  '           •.':"•'•.      '      '   - '   "        .,  •    35

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Aquablast
  A surface cleaning process which can be applied to any material where an              ^
  abrasive material is suspended in water.  The resulting slurry is pressurized             t   ;
  and ejected through a nozzle. Since higher pressures can be used in this
  process than in other types of blasting, surface metal can be quickly removed
  and leaving a good surface finish.

Blasting
  See' listing by specific medium (e.g. Abrasive, Dry, Grit, Shot, Aqua).

Borax Treatment
  A method of  coating steel with a thin film of dry lubricant. .After surface
  cleaning or acid pickling,' the material is placed in a hot borax solution,
   allowed to come to solution temperature and removed and dried. The
   resulting alkaline coating imparts lubrication for subsequent drawing
   operations and provides minor corrosion protection.

Boriding
   A high temperature process used for surface hardening of mild low carbon
   steels.        .                                          ••"-.

Bright Chrome Plating
   Decorative chromium plate deposited directly on a nickel plate substrate.

 Bronzing
   A chemical process generally applied to steel to impart the appearance of
   bronze (antimony chloride in hydrochloric acid followed by ammonium
   chloride in dilute acetic acid). The resulting "bronze" film does not have the
   corrosion resistance of a true bronze.

 Buffing                          .       :
    A specific type of mechanical polishing using a high speed disc made from
    layers of cloth, leather or plastic impregnated with an abrasive. The
    workpiece to buffed is pressed against the disc.

 Burnishing        .                     .
    A form of metal finishing where the surface is treated mechanically so that no
    appreciable metal is removed but the surface is smoothed.

  Carbonitriding
    A surface hardening technique for steel in which a hydrocarbon (e.g.
    propane butane) and ammonia are are injected into a furnace (750 -800 o)
    containing  the workpiece.  The resulting atomic carbon and nitrogen react
    with the surface-iron to form iron carbides and iron nitrides.

  Carburizing                                                                      .
     A process  used for certain types of ductile steel which increases surface
     hardness from two to six-limes. It generally is conducted in a heat resistant
     box containing an atmosphere of carbon monoxide, carbon dioxide,water
     vapor methane, hydrogen, and butane in correct ratios and heated to 900  C.
                                    w/isrr MINIMIZATION ;NTHCMCT*LF/N/SH/NC INDUSTRY.

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     Case Hardening
        A family of surface hardening processes generally applied only to steels.
        (See specific listings for carbonitriding, carburizing, chromium plating,
        cyanide hardening, electroless nickel plating, nitriding.)

     Casting                                                         .  '
        A general term covering a production technique where any metal is
        heated  until it is molten and then poured into 'a mold, allowed to cool and
        solidify..  .    •         ,       ,  .                         "  .   „

     Cathodic Etching
        A technique applied to steel workpieces where the workpiece is made the
        cathode in an.electrolytic cell with sulfuric acid as the electrolyte. The
        anode will generally be lead or stainless steel.  When a current is applied,
        hydrogen will be evolved at the cathode and the surface metal oxide will
        be reduced. The technique  is usually applied immediately prior to    -
        electroplating.                            ,                     •

     Cathodic Protection
        A technique applied to steel where metals anodic to iron (eig. zinc,
        aluminum, magnesium) are applied to the surface on the steel workpiece
        to provide a corrosion resistant surface. The process relies on the fact
        that where a cell exists between two metals with an electrolyte, one of the
        metals will corrode and in the process of corroding protect the other
        metal.         • ,                       ;

     Chemical Polishing
        A process carried out on mild- and low-alloy,steel,,stainless steel,
        aluminum. Special solutions are used to attack  the surfaces of these
        metals in such a manner that the peaks or corners are affected in
        preference to the concave surfaces.  The result is a general smoothing of
        the surface.

     Chrqmate Coating (Chromating)
        A corrosion protection technique which has  many variations and can be
        applied  to steel, aluminum, magnesium, and zinc.  It results in the
        formation of metal oxides  on the surface of the  workpiece which reacts to
        form metallic chromates.  Chromating of aluminum and magnesium
        improves corrosion'resistance considerably. With steel it is much less
        permanent.-        .                        ,    ,            ,

     Chromium Plating                                  •
        This electrodeposition of chromium is generally applied to steel in all its
        forms.  It is usually done for decorative purposes (bright  chromium) or to
        provide a hard surface for engineering purposes (hard chromium).
        Chromium plate is nearly always deposited  on top of a nickel deposit.'
        The  nickel deposit supplies the necessary eorrosion resistance. '.  •  - •
                • \  '   ,   '         : '       .    "'\. '       •       •      - ' '
        Chromium plating solutions contain chromic acid (500 gm/l) and sulfuric
        acid(5gm/l). Proprietary additives are sometimes used to improve
        throwing power, regulate the solution and to help the distribution of
        current.  •        •               •               .
.GLOSSARY* •     .'        •       .   '".-'.-•     -''-..'          '              .    , ,   -•"•'  37

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miiiilliiillllllilillii               •  ,   • •    •   •  •    .    •  /  •  	,.   •    ••       .  •   •   ,
                    Chromizing
                      A treatment applied to mild- and low-alloy steel only.  It is a surface diffusion
                      process in which chromium is alloyed with iron to give a chromium-rich
                      surface layer.
                      Thoroughly cleaned workpieces are'placed in a heat resistant box with a
                      proprietary powder of an unstable chromium compound. When the box is
                      heated to over 1000° C, the chromium decomposes into an active state which
                      reacts with the iron to produce an alloy. The longer the workpiece is retained
                      in the heated box the deeper the penetration the chromium alloy.

                    Cold Galvanizing
                      A term sometimes used to differentiate between electroplating zinc on steel
                      from the hot dipping of steel in molten zinc. It can also refer to a form of
                      painting with specialized paints which result in a film of up to 90% powdered
                      zinc.  The purpose of all these processes is to provide corrosion resistance.

                    Color Anodizing
                      A process used only on aluminum and its alloys using dyes to color the
                      anodic film.  The anodic process produces  a porous film which when fresh
                      will absorb dyes.  The anodizing is carried out using the sulfuric acid process.
                      After completion of the anodizing the workpieces are rinsed in cold water and
                      placed in a dye solution. After dyeing, the workpieces are again rinsed in
                      cold water followed by immersion in nearly boiling water. The heat seals the
                      anodic film and the surface remains permanently colored.

                    Contact Tin Plating
                      A form of electroless plating commonly used in thfe printed circuit board and
                      general electronics industries to improve solderability of workpieces. The
                      workpieces are immersed in a hot chemical solution containing unstable tin  -
                      compounds. The tin reduces on the surface of the workpieces.

                    Copper Plating
                       Copper is electrodeposited for conductivity in the printed circuit and electrical
                       industries, and for decorative purposes.  There are four basic types of copper
                       plating solutions; copper sulfate, copper cyanide, copper pyrophosphate, and
                       copper fluoborate.
                       The oldest technique uses copper sulfate (200 gm/l), sulfuric acid (30 gm/l)
                       and potassium (12 gm/l).  Modern solutions use proprietary additives which
                       make it possible to plate at higher temperatures and with a high "leveling"
                       action.                               .
                       Copper cyanide solutions are often used when steel is to be plated.  It
                  -    produces a thick, dense,, non-porous film.  A typical copper cyanide solution
                       consists of copper (8 gm/l), and free sodium cyanide (5 gm/l).
                        Like cyanide, copper pyrophosphate solutions can be used for plating on
                        steel provided an initial "strike" is made  before plating. The "strike" solution
                       will usually contain copper (5 gm/l), pyrophosphate (60 gm/l), oxalate (5 gm/l)
                        and chloride (10 gm/l). "It-may be heated up to 50° C.  After the "strike" the
                        workpieces are placed in tn& standard pyrophosphate plating solution which
                        contains copper (20 gm/l), pyrophosphate (160 gm/l), oxalate (17 gm/l) and
                        ammonia (6 gm/l). The pH ofthe bath must be maintained at 8.4. Additives
                        are generally present to give good "leveling". Pyrophosphate solutions
 38                    '                               WASTE MINIMIZATION fN THE MFML FINISHING INDUSTRY

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       require careful control and are more expensive than some alternatives,
       but give a bright, dense deposft with good throwing power.

       Copper fluoborate solutions are used when a rapid build up of thick
       deposits is necessary.  Tight laboratory control is generally required for
       optimum plating efficiency. A typical solution contains copper (120 gm/l),
       fluoboric acid (30 gm/l), and is operated at 45° C.

    Corrosion
       Corrosion occurs in all  metals at some time and can be divided into four
       basic forms.  Room temperature oxidation, by far the most common form,
       is most obvious in mild and Ipw-ailoy steels.  The process is accelerated
       dramatically by comparatively small amounts of contaminants like
       chloride, sulfate, and fluoride.                                     ,

       When exposed to high  temperatures, metals will almost invariably result in
       oxidation of metal surfaces. Chemical corrosion is the result of attack by
       acids or alkaline compounds which dissolve the metal surface.
       Electrolytic corrosion occurs when two metals in contact with  each other
       have different' electrode potentials.  It 'is a major contributor to most of the
       corrosion found in steels.

    Cromodizing
       A name given to the chromating of steel where a film of iron chrpmate is
       formed on the surface. 'The corrosion protection provided by this
       treatment is of a very low order. "Phosphating" and oiling will probably
       provide superior corrosion resistance without the use of chromium.

    Cyanide Hardening
       A surface hardening technique which uses molten cyanide salts to give
     ,  workpieces a case containing carbon and nitrogen. Temperatures of
       650° C to 80° C must be maintained for 20-30 minutes to 6e effective.
       The high toxicity of the  cyanide used makes it expensive because of
       treatment requirements.        '    ,
                                   ' •  ' "       -       •
    Degreasing
       A form of cleaning which generally uses chlorinated solvents. In the most
       common form, a liquid solvent is heated in an open topped container. As it
       boils a hot vapor rises above the .liquid.  The vapor js held within the
       container by means of a cooling coil which runs around the inside, of the
       container a short distance below the rim. This cold zone causes the
      . vapor to condense and be returned to the  sumpfor rebelling.  It is
       therefore a form of continuous distillation.
       When any cold component is placed in the container, the vapor
       immediately condenses on the surface.  The solvent dissolves any grease
       on the surface arid as further solvent condenses it runs off the workpiece
       carrying the soluble soils into,the sump.

     Descaling                 .             X
       This term describes a process that can be applied to all materials to
       remove scale.' Scale is generally produced during manufacture or storage
GLOSSARY                    '                  .              '  "   ,      -                     39

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  and it may be obvious such as rust or millscale or it may be very unobtrusive.

  The various methods of descaling include blasting, pickling, acid or alkaline
  sodium hydride treatment, and polishing.

Die-casting                              •
  A method of casting in which molten metal is poured, sometimes under
  pressure, into a mold or die. The die is made of metal and immediately after
 " solidification of the casting the die opens and the casting is ejected.

Dry Blasting
  A general name given to any form of blasting where the abrasive agent is not
  carried in water.

Dry-form Lubrication
  A form of painting applied to steel surfaces of workpieces subject to light
  wear or abrasion. It generally uses colloidal graphite or molybdenum
  disulfide carried in a phenolic resin.

Electrocleaning                                            >  '
  An electrochemical cleaning process by which a workpiece is first made the
   cathode in an electrolytic cell. When current is applied, the generation of
   hydrogen gas from the electrolysis of water at the surface of the workpiece
   results in a highly efficient scrubbing action. Following initial treatment as a
   cathode the circuit is reversed so that the workpiece is the anode. Oxygen
   gas, which is generated at the surface produces a final cleaning action.

 Electroforming
   A specific form of electroplating used where intricate shapes and relatively
   thin metal deposits are required. .Molds of plastic, wax. or sometimes metals
   are made conductive by application of carbon or metallic powder and are
   plated by conventional methods.  Nickel, copper or precious metals are
   generally selected for plating. The mold is generally removed at the
   completion of the plating process by one of a number of methods depending
   on the material from which the mold is constructed.

 Electrogalvanizing
    See "Zinc Plating"

 Electroless Plating
    When a metal is immersed in a solution of another metal with a higher
    electrode potential, that dissolved metal will displace the lower potential metal
    on the surface of a workpiece. The best known electroless plating process
    occurs when steel is placed in a copper sulfate solution.  Copper is plated
    without the application an external electric current.
    In another common  electroless process, aluminum, which rapidly forms
    aluminum oxide in conventional electrolysis, is plated with zinc. The zinc
    deposit can then be subsequently electroplated using conventional
    techniques.
                                                              '
                                    WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY  .

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     Electroless Nickel Plating
        In this process an alloy of nickel and phosphorous can be applied to
        almost any metal, and to many plastic materials including- glass.  Prior to
        nickel deposition, the workpieces must be cleaned to a very high standard
        and then "etched" or "sensitized" before they are immersed in the
        electroless nickel plating solution. The solutions must be heated above
        80 C for good adhesion to be achieved^         ,

        Electroless nickel plating has found considerable" use in two major
        applications. First it is employed where good corrosion resistance is
        required on intricate shapes, crevices, blind holes and deep cavities
        where conventional electroplating is not possible. Electroless nickel
        deposits occur in homogeneous, uniform manner on all surfaces as
        opposed to in electrolytic plating where there will always be areas of high
        current density, such as edges and points where deposits are thicker, and
        areas of low current density, such as recesses, where deposits are
        thinner.           .                .
              '"'."!'   -    '           -~ •     .         "   -  '    -  '
        The second major area of use is where, after electroless plating, heat
        treatment is employed to obtain a high surface hardness.

     Electrolytic Etch
        A technique generally applied to steels which attacks the surface to
        produce a clean, oxide free material. It is often used prior to
        electroplating, especially chromium plating.  Since it preferentially attacks
        edges it  will open up minute cracks in the metal surface allowing
        Electrolytic etching to be used as an inspection technique.      ,

     Electrolytic Polishing
        An electrochemical process usually applied to steels and aluminum and
        its alloys which produces a bright surface with a highly reflective finish. In
        most instances this is used for decorative purposes and it often
        associated with some other form of metat finishing such as anodizing,
        plating, or lacquering.

        In electropolishing the workpiece is made the anode in an electrolytic cell.
        When current is applied metal is removed from the anode surface.
        Corners  and peaks are preferentially dissolved because of the higher
        current density surrounding them. The result is the surface of the
        workpiece is smoothed.

        The electrolytes employed generally are sulfuric acid, phosphoric acid or
        chromic  acid.  Alternatives methods of polishing include "barreling" or
        other forms of mechanical polishing, and vapor blasting..

     Electro-osmosis
     •   See "Reverse Osmosis"

     Electrostatic Painting
       , A form of spray painting using specially.formulated paints with pigment
        particles which will accept a static electric charge and be carried in a non-
        polar solvent.  Paint guns eject the paint at a slight velocity. The particles
                           .    .    •  I         -  '      :       •      '  ..."    /   /             41

. GLOSSARY                             '    ;              '•         •.--'•'''    ;  ' . '   .      ,...,'

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                     leaving the gun are given an electrostatic charge of anything up to 30,000'
                     votts. Very small currents are employed so the safety hazard is negligible.
                     The workpiece to be painted is at earth ground and thus ther6 is considerable
                     attraction between the paint and the workpiece. As the paint particles arrive
                     at the workpiece, they are attracted and adhere to the surface. This results in
                     the neutralization of the static charge, and added attraction of the paint
                     particles to areas which have not been painted.

                   Emulsion Cleaning
                     A cleaning technique which acts by emulsifying contaminants.  Emulsions are
                     mixtures of two liquids, with one liquid holding the other one in a suspension
                     similar to a colloidal suspension.  The liquids will typically have different
                     polarities and will dissolve different types of materials. One of the liquids is
                     usually water and the other will have non-polar properties.  They can
                     therefore be used to dissolve non-polar contaminants like oil and grease from'
                     metal surfaces.
                     With proper use emulsion cleaners can have a long useful life and produce
                     very clean surfaces. They may have to be formulated specifically to clean
                     certain soils.

                   Etching
                     Etching may be used as a surface preparation technique prior to
                     electroplating (see "Activation") or for removal of metal such as in the printed
                     circuit industry where material not required on  the finished product on the
                     final printed circuit is removed by a chemical solution.
                     It can also be used as an inspection technique due to its ability to accentuate
                     surface cracks and defects.  Even minute surface defects will be highlighted
                     since the edges are preferentially dissolved..

                   Evaporation Process
                     See "Vacuum Deposition"

                   "Ferrostan" Process
                    ' A method of continuous electrolytic tin plating of steel strip in which cold
                     reduced strip is continuously fed through the cleaning, etching, plating and
                     rinsing processes. The solution is generally an acid sulfate which produces a
                     matt finish.

                   Fire Gilt Process
                     A process confined to the jewelry trade in which gold dissolved in mercury
                      (gold amalgam) is wiped on surfaces to be plated.  When the article is heated
                     the mercury is  driven off leaving a gold film. The process represents a
                      considerable health hazard due to the emission of the mercury vapor.

                   Fluxing
                      A process used in the heating of metals which may be intended to reduce or
                      eliminate oxidation, confine the products of oxidation, reduce their melting
                      point, and improve fluidityof surface metal layers. Fluxing is generally used
                      in casting, welding and soldering.
42                                                   WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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     Frosting
       A type of metal finishing where a fine matt finish is produced by using
       techniques such as acid-etching, blasting, scratch brushing or barreling. .

     Galvanic Protection
       A general term used in the corrosion protection of steel. Technically, it
      , refers to a metal used to protect a metal higher than itself in electrode
       potential. In practice, it refers to the use of zinc to protect steel.
          i •          •         •            >           ' .     .          .
     Galvanizing
       A corrosion  protection technique applied only to mild steel,  cast iron, and
       steel alloys in which workplaces are immersed in liquid zinc at 500° C.  A
       zinc/iron alloy is formed at the surface of the workpiece giving it an
       adherent coating of zinc.           .

       Prior to galvanizing, the metal surface must be in a moderate state of
       cleanliness. This is generally accomplished by light acid pickling or
       blasting. -                           .  .

       Galvanized coatings are generally about 0.005 inches thick and can give
       a protection for 10 to 20 years.   .       .         »_.

     Gilding
       A process in which gold is coated on the surface of another base metal.
       Gold leaf, a  layer beaten or, rolled so thin it is porous to light, is glued or
       beaten onto the article to be gilded. A similar method applies a fine gold
       powder mixed with a flammable liquid solvent applied to the article like a
       paint. The solvent is allowed to evaporate or in some cases may be
       ignited.

     Gold Electroplating                                               '
     .  Gold has two specific properties which make it valuable in industrial and
       commercial  uses, it resists oxidation and corrosion to a very high degree
       and it retains its attractive color.                         ,

       In industry, gold is now finding considerable use in the electronics field.
       While gold has a conductivity of only 60% that of copper, it has the
       advantage that it.will retain that conductivity over a wide variety of
       conditions.  .                     •                            '  '

       Traditionally, gold has been plated from high concentration cyanide
       solutions which are often produced by immersing the gold in the cyanide
       dissolving the metal as gold cyanide.  The solution may then be used as
       the electrolyte with an inert anode.          .."'-.

       The main advantage of gold plating over other methods of applying gold
       to surfaces,  is that electroplated coatings do not have pores as gilded
       coatings do. this provides significantly greater life and corrosion
       resistance.

     Grit Blasting
       A technique of abrasive cleaning or surface preparation using sharp
       particles (e.g. cast iron shot, aluminum oxide). It covers such processes
  '."    •-'••••'     '    •    •-            "  ,  •.  :   '.'•':.    '••   '•••'••-.'"  -43>
GLOSSARY                              ,           .                '-••'•.

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•IIIIIIIIHIIlllllIllllli                           .                                    M^rffni,,
                      as removal of scale, corrosion, paint and other surface, films.  Use or,tree
                      silica presents a health threat and should be avoided.

                    Hard Chrome Plating
                      See "Chromium Plating"

                    Hard Facing
                      A term referring to processes used to harden metal surfaces and impart wear
                      resistance by a variety of heat treatments. Also see "Metal Spraying"

                    Hot-dip Coating
                      See "Galvanizing"

                    Hydrogen Embrittlement
                      A defect which occurs during the electroplating process. Atomic hydrogen is
                      produced at the cathode of the workpiece being plated. This atomic
                      hydrogen" is extremely  reactive arid has the capability of entering the
                      interstices of the metal. Being unstable in the atomic state, the hydrogen will
                      combine as rapidly as possible with other atoms to form molecular hydrogen.
                      This molecular hydrogen, having a higher unit volume than atomic hydrogen,
                       results in internal pressure in the plated metal.

                    Immersion Plating
                       A plating technique similar to electroless plating where a more electropositive
                       metal dissolved in an electrolyte is plated onto the surface of a less
                       electronegative metal workpiece.  The term immersion  plating is used where
                       a deposit is obtained and the plating process then stops.  This is
                       distinguished from electroless plating where the deposition of the metal being
                       plated continues to be deposited as long as the workpiece remains in the
                       solution.

                     Inchrom Process
                       See "Chromizing"

                     Indium Plating                                      ....
                        Indium is a metal not unlike lead but with friction, and corrosion resistant
                        properties  which are unique. In fact, the sole purpose of indium plating is
                        improving the friction characteristics of very high-rated bearing.

                     "Kanigen Plating"
                        Rrst proprietary process for electroless nickel plating.  For more information
                        see "Electroless Nickel Plating"

                     Lacquering                                        .
                        A term which refers to applying a clear non-porous varnish, to protect an
                        existing finish. Most lacquers are cellulose-based nhatenals in which
                        cellulose is dissolved in a solvent. They are generally applied by 'spray or
                        brush. The solvent is allowed to evaporate leaving a thin film of cellulose
                        remains on the metal surface.
     .                                                  WAST£ MINIMIZATION IN THE METAL WISHING INDUSTRY

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     Lead Plating
        Lead plating does not have many common uses except in the production
        of electrodes for lead acid batteries. Steel, which has been plated with
        lead is much stronger mechanically and lighter than the same thickness of
        pure lead. It is also used as a base layer for indium plating. Lead plating
        solutions contain approximately 100 gm/i lead and 40 gm/l fluoboric acid.

     Leveling                      \
        EIe<:trodeposited metals tend to be concentrated at sharp corners, peaks
        and ridges, due to the fact that current distributed on a surface will tend to
        concentrate at these irregularities much more than in concave surfaces
        such as recesses. Therefore, when a workplace with a rough surface is
        electroplated, the rate of deposition will be faster on these the convex
        irregularities. The result will be accentuation of the item's original       '' <
        roughness.

        To counteract this effect, additives are added to the electrolyte solution
        which produce a polarization effect which is concentrated at the peaks
        and ridges. This polarization effect lowers the current density at me
        peaks and thereby reduces the rate of deposition.  The net result is to
        smooth or "level" the metal surface.

     Metal Coloring
        Dyes applied after anodizing or plating to color-code (ie. identify) parts.

     Metal Spraying
        The general term is applied to the spraying of one of several metals onto ,
        a metal substrate. In general, ft is intended to produce three effects.  The
        first, cprrosion protection, usually involves spraying zinc or aluminum on
        structural steel components. It is also used on high tensile workplaces
        such as those used in aircraft, which cannot be electroplated due to
        hydrogen embrittlement.                           ......
        The second purpose for metal spraying is "hard facing". Materials used in
        hard facing are tungsten bearing or tungsten carbide materials, cobalt and
        nickel with  small amounts of chromium, and high manganese chrome
        materials.  These materials provide significant resistance to wear.

        The third application for metal spraying is for salvage purposes.  When
        engineering components are found to exhibit wear while in service,
        technical and economic considerations may make metal spraying to
        replace the wear a better alternative to replacement.
        The most common method of metal spraying is "flame impingement". The
        technique uses powdered metal continuously fed into a high velocity
        flame. The flame atomizes the metal powder into a molten state and the
        particles are then projected by the energy of the flame onto a prepared
        metal surface.

        Plasma coating is a similar method which employees radio frequency-
        induced plasmas at temperatures up to 30V000° C. This method is limited
        to high integrity components where excellent adhesion or sophisticated
        materials are required.
GLOSSABX

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MIIIIHIIIIIIIIillllli         •	,	••    -	
                    "Micro-Chem''
                      A proprietary electrocleaning process used for "brightening" and "passivating"
                      stainless steel. It is a form of electropolishing  which gives a considerably
                      smoother and shinier finish.

                    Nickel Plating                                        .
                      A very common form of electrolytic deposition which is generally used as an
                    ,  undercoating for subsequent deposits. There are three common solutions
                      used in nickel electroplating; Watt's solution, sulfamic acid, and electroless
                      plating. For a complete discussion of the latter, see "Electroless Nickel
                      Plating".
                      Watt's solution typically contains nickel sulfate (300 gm/l), nickel chloride
                      (50 gm/l) and boric' acid (35 gm/l). The mixture of constituents is necessary -
                      to properly balance the solution. Nickel chloride is required to counteract
                      nickel sulfate's low conductivity. Without boric acid to act as a buffer, the
                      plating process would make the solution increasingly more acidic. Baths are
                      usually maintained at 40d C or above to achieve the best results.

                      Nickel sulfamate plating is a more recent development.  It uses a solution
                      containing nickel sulfamate (500 gm/l), boric acid (30 gm/l) and nickel
                      chloride (5 gm/l).
                      Nickel plating is most often used to prior to deposition of bright chromium
                      deposits for decorative purposes or where a very hard surface is required.   ,
                      For this reason nickel plating is usually applied in a "bright" condition.
                      Because of the high cost of nickel it is often applied over a bright copper
                      deposit. The bright copper deposit does the initial leveling of the surface of
                      the workpiece so only  a relatively thin layer of nickel is required.
                          it                   i.                                          '
                    Nitriding
                       A surface hardening process which is applied only to certain types of steel
                       which results in the hardest surface attainable by heat treatment.  The
                       process consists of maintaining workpieces in a 500° C ammonia atmosphere
                       for up to 100 hours. Under these conditions atomic nitrogen combines with
                       surface, iron to form iron nitride. The nitrogen slowly diffuses away from the
                       surface as long as the proper temperature is maintained. The resulting case
                       thickness is therefore  dependent on length of the heat treatment.

                     Passivation
                       The cleaning of stainless steel with nitric acid to remove carbon and other
                       impurities.

                     Phosphatihg
                       A process by which the surface of a steel .workpiece is  converted to iron
                       phosphate usually as preparation for painting.  Before phosphating, surface
                       must be free from rust and scale. This is usually accomplished.by  acid
                       pickling or mechanically by wire brushing or blasting.

                        Phosphating takes a  relatively short time, usually five to twenty minutes.
                        Solutions are usually maintained between 60° C and 90° C. Workpieces are
                        generally either painted drchromated within 24 hours after treatment since
                        the corrosion resistance imparted by phosphating is poor.
  *C                                   •   .'•            WASTE MINIMIZATION IN THE METAL FINISHING INDUSTRY

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    Pickling
       A chemical treatment which removes oxide of scale from the surface of. a
       metal.  It most often refers to the use of sulfuric or hydrochloric acid to
       remove scale formed on mild and low-alloy steel during hot forming
       operations. Treatment of stainless steel or high nickel alloys; is done with
       hydrofluoric acid, a particularly hazardous material which must be handled
       with extreme care.

    Reflowing
       A technique used in the printed circuit board industry in which a
       component is heated in order to melt solder deposits and cause them
       flow. It produces a bright attractive looking material, but its main purpose
       is for quality control. With reflowing,  any defect on the substrate will not
       wet, clearly indicating areas\where solder is missing.

    Rustproof ing
       A general term which refers to processes applied to steel. It may include
       painting or galvanizing, but most often refers to phosphating and similar
       low duty rust preventatives.                                         ,

    Sacrificial Protection               -            ,
       A corrosion protection technique which uses a metal of lower electrode
       potential to protect a metal of higher  electrode potential. This is possible
       because in the'presence of an electrolyte an electrochemical cell is    ,'
       established in which the lower potential metal acts as a anode and the
       metal to be protected acts as a cathode. The anode corrodes and
       deposits on the surface of the cathode. In practice, zinc and aluminum
       are the two metals most commonly for sacrificial protection
               - -                 *"'„•'-    " '    .•'•'•'         '"    '
    Sealing           ,
       A term commonly applied to any metal process having a subsequent
       treatment capable of affecting this previous process in order to give
       increased corrosion protection (i.e. anodizing^ phosphating).'

    Sensitizing
       A relatively non-specific term used to cover a range of metal finishing
       processes which improve the treatability of a metal surface for a •
       subsequent process. It often refers specifically to a part of the electroless
       plating procedure on plastics or non-metal surfaces. After the surface has
       been etched it is reacted with solution which deposits a very thin film of a
       metal or metallic compound. The surface is then referred to as sensitized.

    Silver Plating;                   '"
       Silver, the easiest metal (for use in plating), is deposited for decorative
    .   purposes on household and jewelry items.  It is sometimes used by the
       electrical industry where it is plated over copper to improve corrosion.
       resistance.        .                                      ,
       A typical silver plating solution contains silver cyanide (19 gm/l),
       potassium cyanide (15 gm/l) and potassium carbonate (25 gm/l).
                                           '  "
GLOSSAKf

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ililllllllllllllllllilll!      !  •         ' "        .  '  .  ' '          .  ' ,             ,  .  •   .      """
                    Solder Plating
                      The term covers the deposition of an alloy of 60% tin and 40% lead which is
                      widely used in the electrical and electronics industries. It provides two
                      valuable features, corrosion resistance and "solderability".

                      A typical plating solution contains tin (stannous chloride, 55 gm/l), lead
                      (25 gm/l) and free fiuoboric acid (40-100 gm/l). Organic additives like glue
                      are often added to the solution to reduce the amount of granular deposits.

                    Solvent Cleaning
                      Solvent cleaning normally uses chlorinated hydrocarbons, methylated spirits,
                      or methyl alcohol. Cleaning with carbon tetrachloride, benzene, toluene,
                      xylene and ether should not be permitted because of health hazards posed
                      by these substances.
                      Workpieces are either wiped with a solvent soaked cloth or dipped in liquid
                      solvent to remove soluble soils. The soil becomes  dissolved evenly
                      throughout the solvent and on the surface of the workpiece when it is
                      removed and evaporated.                                  .

                    Solvent Degreasing
                      See "Vapor Degreasing"

                    Stop-off
                       Method of protecting portions of workpiece surface from chemical processes.
                    1   Waxes, lacquers or special tapes are applied to areas to prevent chemical
                       attack or deposition.

                    Surface Hardening
                       A general term referring to methods for making the surface of steel
                       workpieces mechanically harder than their inner portions. .Also see:
                       "Nitriding", "Garburizing", "Cyanide Hardening", "Carbpnitriding".

                    Ultrasonic Cleaning
                       A sophisticated method of cleaning in which adherent soils are removed by
                       ultrasonic energy applied through liquid. The energy takes the form of cycles
                       of positive and negative pressure in the surface of  the workpiece. With a
                       liquid acting as a working fluid, the high frequency  (up to 10 KHz) pushing
                       and pulling loosens even tightly adherent soils. It is particularly effective on
                       surfaces placed directly in the tine beam of energy. It has limited application
                       Where intricate shapes with many recesses require cleaning.

                     Vacuum Deposition
                       A process in which certain pure metals are deposited on a substrate.  The
                       technique relies on the fact that, in a vacuum, pure metals can be vaporized
                       at a tow temperature in a closed container. The metal vapor will condense
                       evenly on all surfaces to give a metallic coating. Aluminum is the most
                       successfully deposited material, producing a highly reflective finish.

                                            c  '••>.       '         :. •           •              v
                                    -   '     :  , -X  '   '    :  '    •    -
  43                                                  WASTE MINIMIZATION IN THE MZTAL FINISHING INDUSTRY

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     Vapor Degreasing
       A form of cleaning which generally uses chlorinated solvents, which have'
       excellent decreasing properties in their own right but also produce vapors
       , which are heavier than air. In a typical vapor degreaser, a solvent is
       heated in an openrtopped container and as it boils it produces a hot vapor
       which rises above the boiling liquid. The vapor is held within the container
       by means of cooling coil which  runs around the inside of the container a
       short distance below the rim.              ,     ..  •

       When a cold workpiece is placed in the vapor zone, the vapor
       immediately condenses on the  surface, producing a hot clean solvent.
       The solvent dissolves any grease on the surface and as more vapor
       condenses and runs off, carrying the grease with it into the sump at the
       bottom of the sump for re-boiling.

     Wetting Agents                                    ;
       Chemicals which reduce the surface tension of water, allowing it to flow
       from work pieces without beading up.

     Zinc Coating
       See "Galvanizing"

     Zinc Phosphating
       A process applied to.freshly zinc plated workpieces which are immersed
       in a zinc phosphate solution acidified with phosphoric acid. The zinc
       surface deposit  is converted to zinc phosphate. The workpieces are then
       immersed in a dilute chromic acid solution to seal the zinc phosphate
       deposits and prevent formation  of unsightly zinc oxide.

     Zinc Plating
       this very cbmmon form of plating is used to provide corrosion resistance
       for steels. There are three widely used types of plating solutions, two of
       which employ cyanide. In the first, a high cyanide solution, typically
       contains zinc (30 gm/l), sodium  cyanide (85 gm/1) and caustic soda
       (25 gm/l).           .

       The second solution is a low cyanide solution. It typically contains zinc
       (8 gm/l), sodium cyanide (8 gm/l), and caustic soda (65 gm/l).  The third
       is an acid zinc solution which typically  contains zinc (30 gm/l), sodium
     .  chloride (25'gm/l), and boric acid (15 gm/l).

     Zincate Treatment
       A pretreatment necessary for aluminum and its alloys before
       electroplating. After cleaning, etching  in chromic or phosphoric acid to
       remove oxide and dipping in nitric acid to activate the surface, workpieces
       are immersed in a sodium zincate solution. Metallic zinc is deposited on
       the surface of the workpiece.  It is then rinsed and immedfately brought to
       the final plating  operation.                          ,
                                            N. '
                                              X
GLOSSAKT

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SECTION III
Studies

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