Recovery of Metals and Other Materials from Chromium Etching and Electrochemical Machining Wastes.
Proc 4th Miner Waste Utilization Symp Chicago Illinois, 1974 May; :346-353
Bench-scale research on the development of practical processes for the recovery of metals and other values from a wide variety of industrial wastes is described. New treatment methods were successfully applied to two types of waste. Spent chromium solutions that were used to etch and brighten brass parts were treated by simple processes to recover separate chromium oxide, copper, and zinc products. Other materials investigated were electrochemical machining wastes, which normally are exceptionally slow in filtering. This characteristic was ameliorated by evaporating the wastes to dryness and diluting back to the original volume with hot water, which increased the filtration rate by factors ranging from 20 to 121. Filtration produced electrolyte solutions for recycling and mixtures of metal hydroxides. A typical hydroxide mixture was reduced with hydrogen to produce an alloy containing more than 60 pct nickel.
Proc. 4th Miner. Waste Utilization Symp., Chicago, Illinois, May 7-8, 1974, PP. 346-353