7631-86-9 NEW METHODS TO PREPARE HIGH-PURITY SILICA.

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Two methods are described to prepare high-purity silica to be employed as a low-cost starting material for solar-grade silicon production. In the first process, abundantly available quartz sand is purified by fusing it with glass forming oxides to form a melt from which the glass fibers are drawn. Subsequent treatment of the fibers with hot HCl leads to an exchange whereby all non-siliceous oxides are removed from the glass network leaving an insoluble matrix of high-purity silica. The second method employs sodium hexafluosilicate (Na//2SiF//6 ), prepared from fluosilic acid, a by-product of the fertilizer industry. The Na//2SiF//6 is thermally decomposed to yield gaseous SiF//4 which is subsequently hydrolyzed in an ammonia solution. With both methods silica having a purity of greater than 99. 99% was obtained. https://www.lookchem.com/CASDataBase_7631-86-9.htm

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