Recovery of gold from computer circuit board scrap using aqua regia.
Computer circuit board scrap was first treated with one part concentrated nitric acid and two parts water at 70 degrees C for 1 h. This step dissolved the base metals, thereby liberating the chips from the boards. After solid-liquid separation, the chips, intermixed with some metallic flakes and tin oxide precipitate, were mechanically crushed to liberate the base and precious metals contained within the protective plastic or ceramic chip cases. The base metals in this crushed product were dissolved by leaching again with the same type of nitric acid-water solution. The remaining solid constituents, crushed chips and resin, plus solid particles of gold, were leached with aqua regia at various times and temperatures. Gold was precipitated from the leachate with ferrous sulphate.
Sheng
Peter P
PP
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada.
Etsell
Thomas H
TH
D011232:Chemical Precipitation; D003201:Computers; D003247:Conservation of Natural Resources / Q000379:methods*; D005296:Ferrous Compounds; D006046:Gold / Q000302:isolation & purification*; D006851:Hydrochloric Acid; D017942:Nitric Acid; D012996:Solutions
D005296:Ferrous Compounds; D012996:Solutions; C020748:ferrous sulfate; D017942:Nitric Acid; D006046:Gold; D006851:Hydrochloric Acid; C022102:aqua regia