Preparation of 6N,7N High-Purity Gallium by Crystallization: Process Optimization

Jianfeng Hou; Kefeng Pan; Xihan Tan

doi:10.3390/ma12162549

Preparation of 6N,7N High-Purity Gallium by Crystallization: Process Optimization

Materials (Basel). 2019 Aug 10;12(16):2549. doi: 10.3390/ma12162549.

Authors

Jianfeng Hou^{1

2}, Kefeng Pan³, Xihan Tan²

Affiliations

¹ Department of Chemistry and Chemical Engineering, Lvliang University, Lvliang 033001, China.
² School of Metallurgy, Northeastern University, Shenyang 110819, China.
³ School of Metallurgy, Northeastern University, Shenyang 110819, China. 1310198@stu.neu.edu.cn.

Abstract

In this study, radial crystallization purification method under induction was proposed for preparing 6N,7N ultra-high purity gallium crystal seed. The effect of cooling temperature on the morphology of the crystal seed, as well as the cooling water temperature, flow rate, and the addition amount of crystal seed on the crystallization process was explored, and the best purification process parameters were obtained as follows: temperature of the crystal seed preparation, 278 K; temperature and flow rate of the cooling water, 293 K and 40 L·h^-1, respectively; and number of added crystal seed, six. The effects of temperature and flow rate of the cooling water on the crystallization rate were investigated. The crystallization rate decreased linearly with increasing cooling water temperature, but increased exponentially with increasing cooling water flow. The governing equation of the crystallization rate was experimentally determined, and three purification schemes were proposed. When 4N crude gallium was purified by Scheme I, 6N high-purity gallium was obtained, and 7N high-purity gallium was obtained by Schemes II and III. The purity of high-purity gallium prepared by the three Schemes I, II, and III was 99.999987%, 99.9999958%, and 99.9999958%, respectively.

Keywords: crystallization; gallium; high-purity; process optimization.