Recovery and Preparation of High-Purity Zinc Oxide From Industrial Zinc Residue
Aiming at the problem that it is difficult to recover valuable zinc from industrial solid wastes such as zinc oxide tailings and waste water sludge,this paper prepares high-purity zinc oxide micro powder via using carbothermal reduction and oxidation method with local industrial zinc-containing solid wastes as raw materials.The thermodynamic process of the reaction between zinc silicate and carbon reduction in the zinc-containing residue was analyzed by a combination of thermodynamic calculations and experimental studies through HSC Chemistry software.The effects of carbon allocation,roasting temperature,roasting time and CaF2 on zinc yield during zinc silicate reduction were discussed,and the results showed that the catalytic effect was most significant at 1 000～1 100 ℃ when CaF2 was used as a catalyst.The optimum process conditions were obtained:the zinc yield reached 97.44％at a temperature of 1 100 ℃,a holding time of 40 min,a carbon content of 20 wt％and a CaF2 addition of 5 wt％.Structural and compositional analyses of the volatilized product showed that the physical phase was hexagonal zinc oxide crystals with a particle size of 2～4 μm and a purity of 99.47％.
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