Hydrometallurgical Processing of the Wastes of Polymetallic Ore Dressing

The possibility of hydrometallurgical treatment of old flotation tailings to extract base and noble metals was investigated. Two samples of old flotation tailings samples containing 0.26% and 0.36% of copper, and 0.22% and 0.23% of zinc were the subjects of this study. Agitation and percolator leaching was performed with distilled water and sulfuric acid solutions (of 0.5 to 10% H2SO4). It was shown that under certain conditions (sulfuric acid concentration) it was possible to achieve selective leaching of non-ferrous metals and obtain solutions with relatively low concentrations of iron ions, which is necessary for further effective extraction of non-ferrous metal ions from the solution. The effect of acid leaching on further gold recovery from the first sample containing 0.7 g/t of gold by cyanidation was investigated. The sample of the tailings after leaching with a 1% sulfuric acid solution was leached with 10% sulfuric acid. After that, the tailings sample and the acid leach residues were subjected to sorption cyanidation. Two-stage acid leaching with 1 and 10% sulfuric acid provided the higher gold recovery than one-stage (49 and 65%, respectively). Also it was shown that pregnant solution obtained during leaching of the second sample with 10% sulfuric acid may be used for oxidative leaching of substandard copper-zinc concentrate that allowed to 13 and 48% of copper and zinc from the concentrate during the leaching at 80∘C. Keywords: flotation tailings, leaching, substandard sulfide concentrates