Studies on zinc recovery from technogenic waste

Abstract

Results from laboratory experiments are presented on extraction of zinc available in waste from lead-zinc metallurgy, mixed with lead-zinc flotation tailings and some waste rock, by leaching it under atmospheric conditions with sulfuric acid (H2SO4) solutions (5 and 10 wt. %) and 30 % hydrogen peroxide in the temperature range of 25 - 80 °C, at leaching time 30 - 120 min. Material leaching with 10 % H2SO4 solution at 70 °C for one hour brings into pregnant leach solution (PLS) around 80 % of zinc available. Imposing an electrochemical impact during the leaching process increases the quantity of leached zinc by around 5 %. Direct electrowinning from the PLS obtains zinc metal of grade 75-76 %. The suggested treatment removes metals-pollutants from accumulated mixed technogenic waste therefore rendering it more environmentally friendly. Experiments showed that old mixed waste from mining, mineral processing and metallurgy activities merits further studies as secondary source of metals.