Electrolysis of Gold from Filtration Waste by Means of Mechanical Activation

The intensification of the gold thiourea leaching from a filtration waste (Košice, Slovakia) using mechanical activation as the pretreatment step has been studied. The leaching of “as-received“ sample in an acid thiourea solution resulted in 65 % Au dissolution. However, after mechanical activation in a planetary mill 99 % of the gold was leached. The optimum redox potential for electrolysis is in the range 500-523 mV for the gold extraction 99.79 % from the mechanically activated sample. The mechanical activation resulted in an increase of the specific surface area of the waste from 0.7 mg to a maximum value of 13.5 mg. The physicochemical changes in the filtration waste as a consequence of mechanical activation had a pronounced influence on the subsequent gold extraction.