Control of silicon solidification and the impurities from an Al–Si melt

• Based on the available thermodynamic parameters and experimental data, metallic impurities are studied in the solidification process.
• The principle for the silicon growth in the Al–Si melts is investigated.
• We propose electro refining as an effective way to recover pure Si and Al.
• We propose an optimized technical process for SOG-Si production.

The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al–Si melt under the temperature gradient as an intensified separation way was carried out. Based on the available thermodynamic parameters and experimental data, the thermodynamic behavior and chemical composition of metallic impurities was studied in the solidification process. The principle for the silicon growth in the Al–Si melts was investigated. The results indicated that the refined silicon grains were successfully enriched at the top of the Al–Si alloy. Then the top part refined silicon was collected by aqua regia leaching. Electrorefining of the bottom part (Al–22%Si) was investigated effectively in view of recovering pure Si and Al. Additionally, according to previous investigation, the optimized technical process for SOG-Si production was proposed.