Gold recovery from electronic waste by pressure oxidation

Abstract

In this study, a pressure oxidative system with ammonium persulfate (NH4)2S2O8 was developed in order to recover non-leaching gold from electronic waste. The effects of (NH4)2S2O8 concentration (0.66-1.31 M), pressure (0-103 kPa) and liquid/solid ratio (15-25 mL/g) on the recovery of gold were studied in two different levels through a full factorial 23 experimental design. The optimum conditions for gold recovery were established in 0.66 M, 103 kPa and 25 mL/g for a reaction time of 5 minutes. With these conditions the metallic substrate (Cu, Fe, and Ni) was oxidized and gold was recovered as a fine coating in a 99.36%. The resulting solution was treated with a precipitation process to produced non-pollutants by-products (CuSO4:5H2O(C); FeSO4:7H2O(C); NiSO4:7H2O(C)).