China Nonferrous Metallurgy

The zinc content in a certain type of chemical fiber sludge reaches 5.98%, indicating a high potential for comprehensive recovery. In this paper, a sulfuric acid leaching method was employed to recover zinc from the sludge. The effects of key factors, including sulfuric acid concentration, leaching time, temperature, and liquid-to-solid ratio, on the zinc leaching efficiency were systematically investigated. Based on the single-factor experimental data, a PSO-BP model was constructed to globally optimize the process parameters, and the optimization results were subsequently validated. The main conclusions are as follows. The optimal process parameters determined by single-factor experiments were: sulfuric acid concentration of 2 mol·L^-1, leaching time of 60 min, temperature of 30°C, and liquid-to-solid ratio of 4:1 mL·g^-1, under which the average zinc leaching efficiency was 97.91%. The optimal parameters obtained from the PSO-BP model were: sulfuric acid concentration of 2.16 mol·L^-1, leaching time of 64.1 min, temperature of 33.58°C, and liquid-to-solid ratio of 4.18:1 mL·g^-1. Under these conditions, the model-predicted zinc leaching efficiency was 98.96%, and the average experimental zinc leaching efficiency was 98.91%, with a relative error of 0.05%, fully validating the accuracy of the optimization model and the reliability of the obtained process parameters. Compared with the single-factor results, the optimal zinc leaching efficiency after model optimization was improved by one percentage point, yielding significant economic and environmental benefits. This study not only provides process parameters and decision support for the recovery of zinc from chemical fiber sludge but also offers a new approach for the intelligent and precise development of solid waste resource utilization processes.