冶金法制备太阳能硅过程的湿法提纯研究

Study of Hydrometallurgical Purification Unit for Preparing Solar-Grade Silicon with Metallurgical Route

湿法提纯作为冶金法路线制备太阳能级硅的前处理工序,可以去除大部分金属杂质,提高最终产品收率。考察了硅粉粒径、浸出剂浓度、温度、时间、搅拌等因素的影响,采用ICP、SEM等对产品进行了表征。当工艺条件为:硅粉平均粒径44μm、w(HCl)=5%、温度80℃、时间6h,处理后产品中杂质w(Fe)=2.4×10-5,去除率为99.2%,杂质w(Al)=6.4×10-5,去除率为80%。描述了酸浸过程在前后不同阶段分别为受反应速度和内扩散控制历程。为太阳能级硅制备工业化开发,大幅度降低成本提供了参考。

As a pre-treatment unit for preparing solar-grade silicon （SG -Si）, hydrometallurgical route could remove most metallic impurities in metallurgical-grade silicon （MG - Si ） and raise the final product yield. Factors such as the particle size of silicon, the mass fraction of leaching agent, temperature, time, and stirring were investigated, and the samples were characterized by ICP, SEM, etc. When MG -Si powder had been leached at appropriate conditions： the average size of silicon powder particle 44 μm,the mass fraction of hydrochloric acid 5% ,reaction temperature 80℃ ,reaction time 6 h. It was found that 99.2% of Fe impurity and 80% of Al impurity in MG - Si powder were removed. The final Fe and Al impurities mass fraction could be reduced to 2. 4 × 10^-5 and 6. 4 × 10^-5 respectively. The leaching process was controlled by reaction rates and internal diffusions at different stages. The experimental results provided the reference to reduce the cost of industrialized development for preparing SG -Si.