Recycling lead from copper plant residue (CPR) using brine leaching - Precipitation - Calcination process

Copper plant residue (CPR) is a hazardous industrial by-product possessing both high toxicity and valuable metal content, necessitating its high value-added utilization. Traditional practices in smelters involve stockpiling and landfilling of CPR, leading to substantial land occupation and water contamination. This study focused on the preparation of PbO and Pb₃O₄ using the HCl-NaCl leaching-conversion-thermal decomposition process, employing CPR as the primary raw material. The effect of various leaching process conditions on the metal leaching rate was explored. A maximum lead leaching rate of 87.65% was achieved under optimal conditions including leaching temperature, liquid-solid ratio, leaching time, HCl molar concentration, NaCl mass concentration, and particle size. The lead content in the leachate was 15.85 g/L. Experimental data indicated that ash diffusion control served as the rate-limiting step in the HCl-NaCl leaching process. The apparent activation energy was determined to be 18.374 kJ mol^-1, with a reaction order of 0.8986 concerning the HCl concentration and an L/S ratio of 0.8124. Additionally, response surface methodology enabled the determination of technological parameters for refining PbCl₂ into PbCO₃ precursors, yielding a conversion rate exceeding 96.50%. Moreover, the technical indicators of PbO and Pb₃O₄ obtained through low-temperature thermal decomposition of PbCO₃ were investigated. The fabricated PbO and Pb₃O₄ exhibited purities of 99.65% and 99.26%, respectively, effectively transforming CPR from hazardous waste residue into valuable products. The process ensures the efficient recovery of lead to its maximum extent and promotes residue recycling.