| Summary: | A new purification method of removing boron from metallurgical grade silicon
(MG-Si) using a high baisicity slag was developed in this paper. The typical
impurities Al, Ca, Ti, B, P etc in MG-Si can be removed by the binary calcium
sillicate slag and it is especially efficient for removing impurity Boron. It
was found that the maximal distribution coefficient of boron between calcium
sillicate slag and silicon reaches to 1.57 when the mass ratio of CaO/SiO2
was 1.5 and the composition was 60%CaO-40%SiO2. It showed that the
oxidizability of calcium sillicate slag was affected and restricted by the
basicity and the mass ratio of acid oxide SiO slag according to the
thermodynamic relationship. The boron concentration in MG-Si can be reduced
from 18x10-6 to 4.5x10-6 and 1.4x10-6, respectively, when using the ternary
slags 40.5%CaO-49.5%SiO2-10%Li2O and 32CaO-38%SiO2-30%Li2O.
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