Abstract
The Bureau of Mines investigations described in this report were undertaken to devise a process to economically recover precious metals and copper from low-grade, complex electonic scrap generated in large quantities by military and civilian electronic operations. Leaching with various media is applicable to certain selected items of electronic scrap but cannot be practically applied to complex mixtures of scrap. A process comprising incineration, caustic leaching to remove aluminum, smelting with a siliceaous slag, and electrolysis recovered 99.9-percent-pure 7,000 ounces per ton of combined precious metals. Silver, gold, and copper recoveries were 93, 95, 87 percent, respectively. Cost analysis indicated that an alternative process using direct smelting of the scrap to make assayable products for sale to a custom smelter would provide better overall financial returns.
