Sulfuric Acid Leaching of High-Arsenic Dust from Copper Smelting

In connection with the deterioration in the quality of the concentrates that are now being produced and the use of recycled raw materials, lead, zinc, and arsenic are circulating in the semifinished products obtained during copper production and usually accumulate in the system in the form of dust. This article discusses results obtained from the sulfuric acid leaching of dust that is left from reduction smelting at the Middle Ural Copper Smelter. In addition to copper and zinc, the dust contains substantial amounts of lead and arsenic (up to 30%). The computer program Statgraphics was used to plan experiments and analyze the results. The effect of temperature and acid concentration on the indices of the leaching operation was studied and it was determined that for the given process parameters arsenic and copper extraction are most affected by the initial acidity of the solution and zinc extraction is most affected by the temperature of the process. The optimum parameters for leaching the dust were determined: temperature – 60°C; initial acid concentration – 25 g/dm³. Performing the leaching operation with these parameters maximizes the yields of arsenic, copper, and zinc (98% As, 39% Cu, 82% Zn), but raising the temperature and initial acid concentration further has almost no effect on these yields.