China Nonferrous Metallurgy

There is a large stockpile of sulfur flotation tailings in a refinery in Qinghai, which contain 2%~3% of Zn, more than 10% of Pb and about 30% of Fe. To address this issue, this plant has adopted, as supporting measure, the pyrometallurgical + hydrometallurgical process to harmlessly treat the tailings. The tailings and hot filtration residue are mixed, pelletized, and smelted in an oxygen-enriched side-blowing furnace, the smelting slag is then fed into a fuming furnace to be volatilized, and the Zn hypoxide is enriched to enter off-gas dust; the produced Zn hypoxide is subject to two stages of leaching plus extraction process to recover Zn and other valuable metals. In this process, the recovery of zinc in off-gas dust is about 80%, that of indium about 75%; the off-gas dust from side-blowing furnace can be recovered and treated; the smelting slag from the fuming furnace can be used to make cement or eco-friendly bricks; the leaching liquid from hydrometallurgical process is returned to the hydrometallurgical system for zinc; the enriched metals and leaching residue can be sold,in this way, the objective of green metallurgy can be realized.