China Nonferrous Metallurgy

Through the statistics of thallium content in zinc-bearing slag, off-gas washing acid and intermediate products of a zinc hydrometallurgy plant, the flow distribution of thallium in the technical process of zinc hydrometallurgy is analyzed and studied to find out the main existing forms of thallium enrichment and bring forward major measures for effectively preventing thallium loss and pollution. Meanwhile, the emphasis is laid on the analysis of the three-stage combined treatment method for thallium-containing wastewater in the zinc hydrometallurgy industry, namely oxidative neutralization and sulfidization, treatment with biological agents, and ion exchange. Compared with ordinary treatment technologies, using this combined treatment method can save 100 kg/d of sodium sulfide and reduce 1.56 kWh/t of energy consumption of wastewater while lessening 2.23 yuan/t of direct cost for wastewater treatment. Moreover, the thallium content in the treated water can fully meet the requirements of the modification list in Emission Standard of Pollutants for Lead and Zinc Industry (GB 25466—2010) to be implemented in 2022.