The Beneficiation of Thal Silica Sand and the Production of High grade Silicon

Silica sand from Bita site of Thal desert, situated in Punjab province of Pakistan was processed to produce nanoparticles using a ball mill. The produced nanoparticles of silica sand were verified using Zetasizer nanoparticles analyzer. It was observed that the ball milling process not only reduced the particle size but also librated the silica particles from the impurities resulting in increased purity of silica in Thal silica sand from 86.60 wt. % to 95.52 wt. % as major impurities consisting of  Al2O3 and CaO, were liberated during grinding and separated during sieve analysis process. The leaching of silica sand nanoparticles with a mixture of HCl and CH3COOH further improved the wt.% purity of silica in Thal silica sand up to 96.60 wt.%.   The beneficiated Thal silica sand nanoparticles were then reduced with Magnesium to produce silicon particles at 900oC with and without the presence of argon atmosphere. The production of silicon particles during reduction was verified with XRD analysis and FESEM with EDX analysis. It was observed that the presence of argon atmosphere during reduction of silica sand nanoparticles increased the wt. % of reduced silicon in processed sample. The leaching of reduced samples with a mixture of HF and CH3COOH futher improved its purity