Leaching of gold and silver from Miller Process dross through non-cyanide leachants

Leaching of gold and silver from the Miller Process dross was investigated using non-cyanide leachants. The dross was found to be very refractory to direct leaching with thiourea as well as thiosulphate. Thiourea leaching of the calcined dross resulted in about 84% extraction of gold, but the leaching of silver was very poor. Salt roasting of the dross enhanced the leaching of both gold and silver. In a two-stage leaching of the salt-roasted dross with thiosulphate followed by thiourea was possible to extract nearly 98.5% of gold and 96.8% of silver