China Nonferrous Metallurgy

A large amount of SO2-bearing off-gas dust is generated during copper smelting process, which turns into acid mud after being sprayed. The acid mud mainly contains lead compounds, and a certain amounts of valuable metals, such as selenium and copper, and some scattered precious metals. An experimental study was carried out with the acid mud produced by a copper smelter as raw material by adopting the process of pressure oxidative leaching-LIX984 extraction for Cu removal-iron powder reduction for Se precipitation-purification of crude selenium, to extract Se, Cu and other valuable elements from the acid mud. The results show that under proper POX leaching conditions, the leaching rate of Se is more than 91% and that of Cu is more than 95%; in the section of LIX984 extraction for Cu removal, the Cu extraction rate is more than 92% and the Cu stripping rate is more than 95%; selenium powder product with 99.26% Se grade can be obtained after the crude selenium resulting from the iron powder reduction is subject to further purification. The process is environment-friendly due to low reagent consumption and zero discharge of wastewater. The research has realized comprehensive utilization of Cu and Se from the acid mud.