Separation of Refined Silicon from Al-Si Alloys by Air Pressure Filtration

The separation of refined silicon from Al-Si alloys through a solvent refining process was studied. Purified silicon particles were separated by air pressure filtration using stainless steel sieves as the filtration media. After the efficient removal of impurities in the refining process, the effects of the mesh number (N), separation temperature (T), silicon content in the alloy (ω_(a)), and pressure differential (p) on the separation efficiency were evaluated. At N = 80, T = 873 K (600 °C), ω_(a) = 45 wt pct and p = 0.25 MPa, the recovery rate of refined silicon was 98.2 pct, and the residual aluminum in the separated silicon was less than 8 wt pct. The separation process was efficient when N = 60 to 150. It was advisable for the separation temperature to approach the eutectic temperature. Efficient filtration could be achieved when ω_(a) = 35 to 55 wt pct. The filtration efficiency was improved with a higher pressure differential, and the separation was efficient at p ≥ 0.10 MPa. The results show that air pressure filtration is a promising method to separate refined silicon.