Efficient recovery of antimony from waste alkali leached lead anode slimes using an activity regulation method with...

The waste alkali leached lead anode slime is a by-product of electrorefining process of lead, which is composed of high contents of antimony, lead, bismuth, gold and silver and well worthy to be recycled. However, some antimony existed in the form of Na₃SbO₄, which was difficult to be deeply reduced, increased the smelting slag viscosity and decreased the antimony yield. Considering the stronger binding affinity of sodium with sulfur than that of sodium with antimonate in a reducing system, an innovative smelting reduction using PbS as additive was proposed to increase antimony recovery in this study. PbS deconstructed Na₃SbO₄ by converting sodium component to Na₂S, ascribed to which the activity for its reduction and then its yield was increased. Moreover, the Na₃AsO₄ reduction was also accelerated, causing the network structure of the molten smelting slag formed by Na₃SbO₄ and Na₃AsO₄ to be restricted and its viscosity to be decreased. It improved the separation of the reduced metal from smelting slag, ascribed to which the bismuth, antimony and lead yields were increased. Higher recoveries of lead, antimony and bismuth increased the recovery of gold and silver due to a capture effect among them. Under the optimized conditions, the yields of antimony, lead and bismuth obtained 95.2 %, 98.3 % and 98.1 %, respectively. This study supplied a creative process for the efficient utilization of waste alkali leached lead anode slimes, which has a great significance to insure the supply of antimony of the world.