In order to find the most effective hydrometallurgical method of removing iron, aluminum and calcium from MG-Si, a variety of acid leaching methods were presented. The research results show that the order of capacity of metallic impurity removal is HF, HCl, HNO3 and H2SO4. The most effective hydrometallurgical method is the leaching by mixed acid with hydrofluoric acid and sulfuric acid. Removal efficiency of hydrochloric acid pressure leaching can improved as the pressure increases. Sulfuric acid and nitric acid even using high pressure leaching cannot obtain high impurity removal rate. The leaching by hydrofluoric acid or mixed acid containing hydrofluoric acid and sulfuric acid is very effective on removal of iron and aluminum, but less effective on calcium.

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