A novel approach of preparing ZnO from ammoniacal leaching solution with high chlorine levels based on thermodynamic analysis

作者：Cao, Huazhen; Zhang, Zefeng; Wu, Liankui; Zheng, Guoqu^*

来源：Hydrometallurgy, 2017, 171: 306-311.

DOI：10.1016/j.hydromet.2017.06.005

• Zinc ammonia complexes
• Thermodynamic analysis
• Precipitation
• Hydrolysis
• ZnO

Thermodynamic calculations for Zn(II)-NH3-Cl- -H2O system have been presented based on free energy minimization algorithms and simultaneous equilibrium principle. Independent predominance diagrams was constructed as a function of Zn(II), NH3, Cl- concentrations versus pH, which indicates that Zn(NH3)(2)Cl-2(s) is the most likely solid phase in near-neutral zinc solutions with high ammonia and chlorine levels. The precipitation trend of Zn(NH3)(2)Cl-2(s) derived from experiments were consistent with the prediction by theoretical calculation. Pure ZnO(s) was successfully synthesized by a two-step hydrolysis approach, in which Zn(OH)(1.6)Cl-0.4(s) was firstly produced from the hydrolytic deamination of Zn(NH3)(2)Cl-2(s) and ZnO(s) was then obtained by the further hydrolytic dechlorination of Zn(OH)(1).Cl-6(0.4(s)).Both temperature and water amount played an important role on the hydrolysis procedure. Zn(NH3)(2)Cl-2(s) can be transformed to Zn(OH)(1.6)Cl-0.4(s) completely at room temperature with liquid-solid ratio higher than 9:1, and Zn(OH)(1.6)Cl-0.4(s) can be thoroughly converted to ZnO(s) at 80 degrees C with liquid-solid ratio of 5:1.

• 出版日期2017-8
• 单位浙江工业大学