Brushing
Case Studies
A 3M electronics products plant was using ammonium persulfate, phosphoric acid, and sulfuric acid to clean
copper sheeting. This cleaning method generated 40,000 lb/yr of hazardous liquid waste. The plant switched to a
rotating brush cleaning system that scrubbed the copper sheeting with pumice. The abrasive cleaning method
generates a nonhazardous waste sludge that can be disposed of in a conventional landfill. The new cleaning system
cost $59,000. The initial cost was recovered in the third year of operation.
3M Company. Waste Stopper: Pumice on Copper. Environmental Engineering and Pollution Control Dept.,
Saint Paul, MN.
Cenex, in Inver Grove Heights, MN, recycles approximately 110,000 30- and 55-gallon drums as part of their
lubricant distribution business. Drums are typically reused (and repainted) 5 or 6 times. Cenex switched from a hot
caustic paint removal system to a mechanical paint removal system utilizing metal and nylon brushes. Cenex
eliminated 164,000 lb/yr of caustic waste generation. The brushing unit generates approximately 12,000 lb/yr of
nonhazardous paint chip waste. The brushing unit cost $110,000 initially and replacement brushes cost $25,000
annually. Waste disposal costs have been reduced from $55,000/yr to $900/yr. Maintenance downtime is now 4
days/yr instead of 16 days/yr. Cenex also saves $6,000/yr on the cost of sodium hydroxide. NET SAVINGS:
$35,000/YR + 12 DAYS/YR DOWNTIME.
Pagel, Paul. 1993. Brushing Replaces Sodium Hydroxide for Paint Removal. MnTAP SOURCE, 8(2):1,
Minnesota technical Assistance Program.
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