Recycling of Al–Si die casting scraps for solar Si feedstock

Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al–30wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells. •Al die-casting scraps represent a source for high-purity Si.•High-purity Si could be extracted by combined centrifugation and solvent refining.•The purity of Si is determined by the impurity level and the rotation start temperature.•The purity of Si extracted from scrap was comparable to that of Si extracted from commercial alloy.