INTERNATIONAL CLEANER PRODUCTION INFORMATION CLEARINGHOUSE

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 )