Leaching behavior of impurities in metallurgical grade silicon subjected to electromagnetic strengthening

Abstract The distributions and morphologies of precipitates in metallurgical grade silicon (MG-Si) were investigated and effects to control solidification rate and electromagnetic strengthening were tested. Decreasing the solidification rate caused the inclusions to become larger, and electromagnetic strengthening enriched precipitates in the center of the melt. Additionally, acid etching of different samples using an HCl–HF mixed leaching agent revealed the evolution of the microstructure of inclusions in silicon. Corrosion results indicate that the HCl–HF mixture is an effective leaching agent that can be used to dissolve impurities in MG-Si. Using this reagent, the total impurity content of the source silicon was reduced from 6320 ppmw to 171.8 ppmw, and the impurity content after controlling the solidification rate or electromagnetic strengthening was reduced to 158.1 ppmw and 99 ppmw, respectively.