Extraction of Non-ferrous Metals from Underspoil Waters


he focus of the study was the acidic underspoil waters of Safyanovskaya copper JSC containing 0.17 g/l of copper and 1.8 g/l of zinc (pH 2.8–2.9). The purpose of the work was research and development of water purification technology from impurities (copper, zinc, aluminum, iron, manganese), suggesting the possibility of copper and zinc extraction in the form of commercial products. The process of copper extraction by cementation with metallic iron was studied. It was shown that this method could allow to extract 94–95 % copper into a concentrate. The zinc extraction from solution after copper removal was studied by precipitation with NaHS, Na2CO3, NaOH and CaO. For economic reasons it is recommended to make zinc precipitation in two stages with CaO in order to produce cake containing 15–21 % Zn with extraction 80–87 %. This cake can be utilized at zinc processing plant. A process flowsheet for acidic underspoil waters, including copper cementation and the precipitation of zinc cake, has been developed. According to this scheme, mother liquor from zinc precipitation should be treated with lime until pH reaches 10–10.5, followed by pulp settling. As a result, purified water of the following composition is obtained, mg/l: zinc – 0.05, copper – 0.01, aluminum – 0.02, iron – 0.02, manganese – 0.05.

Keywords: underspoil water, copper, zinc, iron, cementation, calcium oxide, concentrate, precipitation

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