A clean process of lead recovery from spent lead paste based on hydrothermal reduction
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Henan Yuguang Gold and Lead Group Co., Ltd., Jiyuan 459000, China)
2. Henan Yuguang Gold and Lead Group Co., Ltd., Jiyuan 459000, China)
Abstract: An innovative process was proposed for recovering lead from spent lead paste, and it produced less pollution and used less energy than the traditional process. First, lead dioxide in lead paste was reduced by glucose under hydrothermal conditions. The effects of the reaction time, glucose excess coefficient, temperature and pH on the hydrothermal reduction were systematically investigated. Under the optimized reduction conditions (i.e., temperature of 175 °C, time of 120 min, glucose excess coefficient of 3.0 and pH of 5.5), 99.9% reduction ratio of lead dioxide is achieved, and only the PbO·PbSO4 and PbSO4 phases are observed in the reducing residue. Subsequently, the reducing residue is desulfurized in a NaOH solution, and approximately 99.40% of the sulfur is removed. The main lead phase in the desulfurization residue is 3PbO·H2O.
Key words: spent lead paste; hydrothermal reduction; glucose; desulfurization