The U.S. Bureau of Mines investigated a hydrothermal sulfidation procedure to recover lead and silver from plumbojarosite. The plumbojarosite, generated during pressure-oxidative leaching of zinc concentrate in a commercial operation, contained, in percent, 25.4 PB, 18.8 Fe, 1.4 Zn, 29.5 So42-, 3.2S deg, and 13.4 Total sulfur, plus 7.4 Oz/ton ag. The sulfidation was conducted in an autoclave and converted the plumbojarosite to amorphous iron oxide and liberated the lead and silver as sulfides. The best operating conditions were using 50 g of plumbojarosite and 7 pct s deg (2.04 G s deg added) in 500 ml of 2.0 Mol/l nh3, 150 deg c, and 1 h. The sulfidation product contained, in percent, 37 pb, 28 fe, 6 s2-, 2 so42-, and 11.2 Oz/st ag. Ferric chloride leaching extracted 98 pct pb and 97 pct ag from the sulfidation product.
Epd Congress 90, TMS Annual Mtg. in Anaheim, California, 2/19-22/90, PP. 13- 20