中国有色冶金

When copper or lead anode slime are treated by pyrometallurgical process, oxide slag, namely bismuth slag, will be produced in the oxidation refining process of silver separation furnace. Bismuth slag is rich in gold, silver, copper and bismuth. When bismuth slag is treated by pyrometallurgy process, the copper removal process adopts the vulcanization method or the melting copper removal method, which has the problems of high production cost and high energy consumption, and gold and silver will entrain the copper slag, resulting in gold and silver dispersion. The existing hydrometallurgy processes for bismuth slag produce a large amount of chlorine-containing wastewater, which increases the cost of wastewater treatment. In this paper, cuprous oxide and copper in bismuth slag is oxidized by concentrated sulfuric acid, and then copper and bismuth are separated under the condition of dilute sulfuric acid. The black copper powder is obtained from the leaching solution by electrowinning, and the crude bismuth can be obtained from the leaching slag by converter reduction smelting. Conditional test results show that under the condition of material-acid ratio of 1∶0.65, liquid-solid ratio of 5∶1, reaction temperature of 75℃, reaction time of 1.5h and stirring rate of 250r/min, the content of copper in bismuth slag leaching residue can be reduced to less than 0.1%, and bismuth can be enriched to more than 46%. This method realizes the open circuit of copper in bismuth slag without producing chlorine-containing wastewater, and has good economic and environmental benefits.