CASE STUDY # 153
1. Headline: General Motors uses climbing-film vacuum
evaporator and oxidation system for chromium recovery and
recovers capital cost in less than two months.
2. Background: See below.
3. Cleaner Production Principle: process modification
4. Description of Cleaner Production Application: A
climbing-film vacuum evaporator, consisting of an etch
tank followed by four rinse tanks, was purchased by GM to
recover chromium from electroplating baths. Three
evaporators were installed on the plastic-preplate line,
and a substantial reduction was noted in the amount of
waste chromium being treated. Two electrolytic oxidation
systems were used to recover chromium that remained in
solution.
Material/Energy Balance and Substitution
FEEDSTOCKS: Chromium electroplating baths
WASTES: Spent bath chemicals, chromium
MEDIUM: Liquid
5. Economics
CAPITAL COST: $170,000 for three evaporators and two
oxidation systems.
OPERATION/MAINTENANCE: Not reported
MONTHS TO RECOVER: Less than 2
DISPOSAL & FEEDSTOCK: $1.44 million in the first year
6. Advantages
FEEDSTOCK REDUCTION: 1.05 million lbs of chromic acid
were recovered in the first year, with an additional
230,000 lbs recovered by oxidation.
WASTE PRODUCTION: The amount of waste chromium being
treated after evaporation was substantially reduced
IMPACTS: Spent chromium electroplating baths requiring
disposal are being evaporated with chromium recovered as
chromic acid for reuse. A reduction in waste volume is
realized along with overall savings.
7. Constraints: No information provided.
8. Contact and Citation: "Catalogue of Successful Hazardous
Waste Reduction/Recycling Projects", Energy Pathways Inc.
and Pollution Probe Foundation, prepared for Industrial
Programs Branch, Conservation & Protection Environment
Canada, March, 1987, page 95.
9. Keywords: United States, USA, automobile, electroplating,
process modification, chrome, vacuum evaporator, chromic
acid, electrolysis, ISIC 3200, automobile
10. Reviewer's Comments: This case study was originally
abstracted for the US EPA's Pollution Prevention
Information Clearinghouse from the Canadian publication
"Catalogue of Successful Hazardous Waste
Reduction/Recycling Projects." It underwent a UNEP IE
funded technical review in 1994 for quality and
completeness. It was edited for the ICPIC diskette in
July 1995.
( Docno unep05: 450-003-A-380 )