Use of an Evaporator in Chromium Electroplating. Compendium on Low- and Non-Waste Technology

摘要

Chromium electroplating, followed by rinsing, and ion exchanger and evaporator unit processing of the rinsewaters to recover solutions for reuse in the plating bath. The chromium electroplating process is the same as the standard technique, except that rinse water reduction techniques are used. The reduced volume of rinse water, containing the dragged-out plating solution, is pumped into a cation exchanger to prevent the buildup of metallic impurities. The rinse water then enters an evaporator unit where sufficient water is boiled off and the concentrate is returned to the plating bath. In the standard bath, the rinse water is chemically treated in order to break down cyanide, reduce hexavalent chromium to trivalent chromium, and preciptate the trivalent chromium and other pollutants. The resultant sludge is then disposed of as a solid (hazardous) waste.