Comparison of Reductive and Oxidative Bioleaching of Jarosite for Valuable Metals Recovery

Abstract

Jarosite is a typical stream of zinc refineries, with high production rates and possible release of metal-contaminated seepage waters during long-term storage in respective disposal sites. Jarosite contains remarkable concentrations of valuable metals, like several weight percentages of zinc and lead, in addition to lower concentrations of copper, silver, germanium, gallium and indium. In this study, jarosite was treated with reductive and oxidative bioleaching for valuable metals recovery. The reductive bioleaching was seen to enhance iron liberation, by transforming the dissolved Fe(III) to Fe(II), while in the oxidative bioleaching iron liberation was lower. Zinc, copper, indium, gallium and germanium dissolution rates were rather identical with both methods. In reactor experiments, the zinc and copper yields were higher than in flask experiments resulting at best in the leaching yield of 35% and 38% for zinc and copper, respectively. Indium and gallium yields were between 5-8%, but approximately 40% of germanium was leached.