Comprehensive recoveries of selenium, copper, gold, silver and lead from a copper anode slime with a clean and economical hydrometallurgical process

A clean hydrometallurgical process has been developed to efficiently and economically recover selenium, copper, gold, silver and lead from a copper anode slime. The mixture of H2SO4 and H2O2 was demonstrated to be effective for selenium leaching based on their synergistic effects, and the potential synergy mechanism was proposed. Na2SO3 reduction and iron powder precipitation were successively adopted to recover selenium and copper from the leaching solution. NaClO3-H2SO4-NaCl solution was chosen to selectively leach gold, and the dissolved gold was recovered by H2C2O4 reduction. Na2SO3 was used to leach silver with a sealed reactor, and the leached silver was recovered through Na2S2O4 reduction. A lead concentrate with lead grade of 57.2% was eventually obtained after extracting selenium and copper, gold and silver. The recoveries of selenium, copper, gold, silver and lead separately achieved 92.9%, 95.8%, 99.1%, 99.4% and 99.8% under optimal conditions, and the purities of obtained products of simple substance selenium, sponge copper, metallic gold and metallic silver were 94.2%, 85.3%, 98.7% and 96.5%, respectively. The element distribution analysis indicated that the most of these valuable elements entered their products while hazardous element arsenic displayed a relatively scattered distribution. The cost-benefit analysis revealed that a revenue of 702217.8 CNY could be gained for treating one ton of anode slime using the proposed process. This process is eco-friendly and possesses high economic benefit, and thus shows good potential of industrial application.