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ZINC SLUDGE RECYCLING AFTER KASTONE TREATMENT OF CYANIDE-BEARING RINSE WATER
Citation:
Moser, J. ZINC SLUDGE RECYCLING AFTER KASTONE TREATMENT OF CYANIDE-BEARING RINSE WATER. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-77/038.
Description:
The purpose of this project was to demonstrate the feasibility of reclaiming sludge. The sludge was produced by the destruction of cyanide by Kastone in zinc-cyanide dragout rinse water. The clear supernatant was discharged to the municipal sewer and the sludge eventually recycled to the plating tank. The general approach was to transfer cyanide-bearing rinse water to the treatment tank, treat, settle, decant clear supernatant, transfer sludge for further concentration and return dissolved sludge to the plating tanks. The possibilities of contaminant accumulation were present. Breakdown products, ferrocyanide, copper and other possible metallics would be returned to the plating tank. The operation at Metal Plating Corporation has two plating tanks. This allowed a control and experimental tank for evaluation. The major difficulty encountered was a precipitate mostly of calcium and magnesium hydroxides that was formed in the treatment process and does not redissolve as does the zinc oxide sludge. The presence of calcium and magnesium is known to be present in the water used. The hydroxide sludge presented mechanical problems in handling in the recycling process.