Electrochemical Reduction of Solid Lead and Antimony Sulfides in Strong Alkaline Solutions

Abstract

Extraction of lead and antimony from their sulfides without SO2 emission is of great significance to tackle the air pollution caused by the conventional metallurgical routes. In the paper, solid PbS and Sb2S3 are respectively electrochemically reduced to Pb and Sb in a 50 wt% NaOH solution. Thermodynamic analysis is conducted to illustrate the feasibility of extracting metals from their sulfides in the alkaline solution. Moreover, a home-made graphite cavity working electrode was employed to study the electrochemical reduction behaviors of PbS and Sb2S3, and their reduction processes were in situ recorded by a camera in a transparent cell. The results show that the strong alkaline solution is able to electrochemically convert PbS and Sb2S3 into Pb and Sb with a current efficiency higher than 90%.