Study on Electrode-Deposition of Zinc by Hydrometallurgy with Pyrolytic Zinc-Containing Paint Slag
Zinc-containing paint slag is the harmful waste residue from zinc-rich anticorrosive coating,which can be used as the raw material of zinc hydrometallurgy after the organic components are removed by pyrolysis.The pyrolytic zinc-containing paint slag was adopted to neutral leaching with waste electrode-deposition solution,purified and electrode-deposited to produce zinc plate,the purified solution composition and powder consumption of which were compared with that adopting crude zinc oxide and zinc powder as the raw material.The result showed that the pyrolytic paint slag with-50 μm size reached the highest ZnO content of 81.88％but the lowest Zn content of 12.95 wt.％,which was suitable for alkaline washing and neutral leaching.The pyrolytic paint slag with 50-125 μm size contained higher metal Zn and was suitable for Cu removal and for two-step removal of Ni,Co and Cd.The pyrolytic paint slag with+125 μm size had the highest metal Zn and Fe contents of 76.01％and 68.79％,respectively,which was suitable for the second stage of Cd removal with 50-125 μm size paint slag.Adopting the above purification process,the solution composition was closed to that purified with the Zn powder,and the sponge Cd products with 20.48 wt.％and 19.68 wt.％content were obtained.Finally,the purified solution was electrode-deposited to produce plate Zn,the current efficiency and power consumption were closed to Zn powder under the same condition,indicating the pyrolytic zinc-containing paint slag was suitable for electrode-deposited Zn production.This research also provided the new direction for the resource utilization of Zn-containg paint slag.
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