Preparation of metallic lead from lead sulfide by bagged cathode solid-phase electroreduction in a low-temperature and weakly alkaline solution

Abstract

Developing a method to recovering metallic lead from lead sulfide at lower temperatures without emitting lead dust and SOx gas holds significant importance in terms of environmental sustainability and economy efficiency. In this study, we employ a bagged cathode to directly produce metallic lead from lead sulfide in a low-cost weakly alkaline electrolyte (200 g/L Na2SO4 + 0.1 mol/L NaOH) at a temperature as low as 40 °C. The use of bagged cathode effectively immobilizes reactants and reduces cathodic polarization, thereby enabling the electro-reduction of lead sulfide under mild conditions. During the electroreduction process, the granular lead sulfide powders gradually undergo transformation into rod- or sheet-like metallic lead, achieving lead recovery ratio and desulfurization rate reaching 96.4 % and 97.9 %, respectively. Cyclic voltammetry analysis confirms that the oxidation reaction of S2− released from cathode is irreversible, thereby not interfering the cathodic electroreduction of lead sulfide. This bagged cathode direct electroreduction method utilizing a low-temperature, weakly alkaline aqueous solution exhibits the potential for application to other sulfides or oxides.