INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

CASE STUDY # 168

1.   Headline:  Reduction of Loss of Precious Metals Through
     Ion Exchange, Electrolysis, and other In-Process Measures
     in an Electro technical Company

2.   Background:  See below.

3.   Cleaner production Principle:  process modification,
     internal recycling

4.   Description of Cleaner Production Application:

     Technology Principle:  This technology involves
     electrolytic        recovery, ion exchange, and wastewater
     treatment to reduce        metal loss from nickel, copper,
     and silver plating processes.

     Case Study Summary

     Process and Waste Information:  The company operates
     copper, nickel, and silver plating lines.  Processes
     within the lines include degreasing baths without
     cyanides, acid staining baths, and pre-silver plating
     baths, baths for plating and unplating silver and copper,
     and nickel baths.

     The in-process measures undertaken include blowing off
     process liquors, electrolytical recovery of silver and
     wastewater treatment.  Rinsewater from the silver line is
     first treated in a cartridge ion exchanger.  Nickel
     containing rinsewater is first treated in a cation
     exchanger at a rate of 15 m3/hr.  Cyanide-containing
     rinsewaters, degreasing waters, and acid stain bath waters
     are treated in a DND installation.  Cyanide- containing
     concentrates are conveyed to third parties, except for the
     silver bath which is reclaimed electrolytically.

     The wastestream of 30,000 m3/yr (1977) of untreated,
     heavily contaminated water has been changed to a stream of
     70,000 m3/yr (1986) of slightly contaminated water.  New
     wastes produced are about 10,000 kg/yr of sludge.

     Scale of Operation:  The plant capacity is about 300,000
     m2/yr, employing 25 people in the galvanizing department.

     Stage of Development:  The changes have been fully
     implemented.

     Level of Commercialization:  All equipment is commercially
     widely available.

     Material/Energy Balances and Substitutions:

Material Category           Quantity Before
Quantity After     Waste Generation(kg/yr):

Sludge                             N/A
10,000     Metals lost in
  wastewater
       Copper                      1000
20-30           Nickel                      1000
30-50           Silver                       350
15-20
  Feedstock Use
  (metric tons/yr):
       HCl                           0
15            NaOH                          0
150            NaClO                         0
150

Water Use (m3/yr):                 30,000
70,000 Energy Use (Dfl/yr):
For blowing off                      0
135,000
For water treatment                  0
35,000
5.   Economics

     Investment Costs:  Investment costs were as follows:

              1977                 210,000 Dfl
              1981                 276,000
              1984                 350,000
                                 15,000

(includes measurements,
                                   etc.)
              Total                986,000

Capital costs are estimated at 100,000 Dfl/yr.  No costs are
associated with sludge removal since the sludge is treated for
metal recovery by a third party in the U.S.

     Operational & Maintenance Costs:  Costs were as follows:

Labor                              190,000 Dfl
Energy                              35,000
Chemicals                          200,000
Removal of strikes                  90,000
Removal of silver baths             90,000

     Payback Time:  As annual costs are estimated at Dfl
     705,000 and savings on wastewater release and purchase
     from copper and nickel salts are 64,500 Dfl/yr and 15,000
     Dfl/yr, respectively, the equipment will not pay for
     itself.

6.   Advantages:  The measures were undertaken to meet water
     regulation demands.  The by-law limits have been met.  The
     limits are 0.5 mg/l of nickel in a substream, 0.25 mg/l of
     nickel in the mainstream, 1 mg/l of copper, and 1 mg/l of
     silver.  The proposed freight demands of 2 kg/yr per metal
     are not met.

7.   Constraints:  No information was provided.

8.   Contacts and Citation

     Citation:

     Wastewater problems in the metal industry: results of
     interviews in 48 companies.  Dr. Ir W.H. Rulkens, TNO,
     Maatschappelijke Technologie, postbus 342, 7300 AH
     Apeldoorn, Netherlands.  Tel: 31-55-773344.


     Industry/Program Contact and Address:

              H. W. du Mortier
              VOM
              Jan van Eycklaan 2
              Postbus 120
              3720 AC Bilthoven
              Netherlands
              TEL: 31-30-287111
              FAX: 31-30-287674

9.   Keywords:  the Netherlands, metal, precious metal,
     electroplating, process modification, recycling, ion
     exchange, electrolysis, nickel, copper, silver, stain,
     rinsing.

10.  Reviewer's Comments:  This case study was originally
     compiled by the UNEP IE Working Group on Metal Finishing.
     It underwent a UNEP IE funded technical review in 1994 for
     quality and completeness.  It was edited for the ICPIC
     diskette in July 1995.


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