RECOVERING METHOD FOR VALUABLE METAL FROM ZINC-LEACHED SLAG BY ROASTING UNDER ADDITION OF SULFURIC ACID

摘要

PURPOSE:To recover Zn, Cu, Cd efficiently by adding a specific amt. of sulfuric acid to Zn-leached slag contg. Zn, Cu, Cd, sulfating Zn, Cu, Cd by roasting the slag in a specified temp. range and decomposing the formed iron sulfate by heating to oxides. CONSTITUTION:Zn-leached slab contg. Zn, Cu, Cd which are hard to dissolve in dilute sulfuric acid is mixed with 1-1.1 times equiv. sulfuric acid based on the total weight of Zn, Cu, Cd, and the mixture is roasted in an air atmosphere at a 600-650 deg.C range by using, for example, a resistance heating furnace. The Zn, Cu, Cd are sulfated but the Fe2(SO4)2 formed by the heating is decomposed because its decomposing temp. is low. Thus the Zn, Cd in the Zn-leached slag is recovered at =95% and the Cu is recovered at =80%.