Abstract:  Scales in the hydrometallurgical process of zinc from several zinc hydrometallurgical plants in China were analyzed by X-ray diffraction，showing that crystalline structure of basic zinc sulfate existed in the form of ZnSO₄·3Zn（OH）₂· 5H₂O，so as to deny traditional view of ZnSO₄·3Zn（OH）₂.Results indicated that the solubility of the basic zinc sulfate had re-lation to the water activity.The target crystallization of basic zinc sulfate was prepared by adding zinc oxide powder into high temperature zinc sulfate solution with crystal structure consistent with scales.At same concentration of zinc sulfate and pH，solubilities of ZnSO₄·3Zn（OH）₂·5H₂O increased with temperature increasing.Research results showed the precipitation temperature of basic zinc sulfate in neutral leaching solution of zinc hydrometallurgy, with zinc mass concentration of 168 g/L and pH= 5.2，was 60.6 ℃±0.4 ℃，and precipitates quantity in the process of decreasing temperature from 80 ℃ to 40 ℃ was 4.4 g/L.

Key words: zinc hydrometallurgy, basic zinc sulfate, crystal form, precipitation temperature