Production and Purification of Silicon by Magnesiothermic Reduction of Silica Fume

• Main Author: Sadique, Sarder
• Other Authors: Barati, Mansoor
• Language: en_ca
• Published: 2010
• Subjects: Solar Grade Silicon; Materials Science; 0794
• Online Access: http://hdl.handle.net/1807/25788

A new approach is discussed for the generation of high purity silicon from silica fume (SF), which is a waste by-product from the manufacture of metallurgical grade silicon. Process steps were developed and optimized including purification of SF, reduction by magnesium, and post-reduction leaching. Reduction was carried out successfully with initial HCl leached SF in a sealed chamber with varying Mg/SF ratios, temperature and time. These variables affected the production of silicon from SF. Suitable reduction conditions were found to be within the temperature range 750-850C and at approximately 2:1 ratio of Mg/SF. Reduction products were treated using a three-stage acid leaching. XRD, QXRD and ICP analyses of the final silicon powder product indicated that silicon with low impurity levels (low boron content) can be produced. Therefore, silicon produced by magnesiothermic reduction can be an attractive source for the production of solar grade silicon.