Pb Recycling Through Leaching, Precipitation, and Cementation from Zinc Plant Residue

This paper presents the hydrometallurgical methods used for the recovery of concentrate and metallic lead from zinc plant residue (ZPR). The ZPR mainly consisting of 9.5% Pb and 7.5% Zn was initially leached by sulfuric acid under the following conditions: leaching temperature 90 degrees C, leaching time 90 min., sulfuric acid concentration 200 g/l, and solid/liquid ratio 1/5. The zinc recovery obtained was 92.8%, which was finally directed to solvent extraction circuit to produce zinc cathode. Then acidic residue was subjected to alkaline leaching, using sodium hydroxide (NaOH). The lead recovery obtained was 92.58%. For precipitation method by using NaClO, the effects of three important factors including (NaClO/solution) ratio, temperature, and precipitation time were studied and reported. As a result, lead was precipitated in the form of PbO2 with concentrated grade of 72.03% and recovery of 92.31%. Furthermore, aluminum was used for cementation process to produce metallic Pb with grade of 96.11% and total recovery of 87.17%.