Partial Purification of Metallurgical Silicon by Acid Extraction

Publisher Website
Google Scholar
Abstract
Metallurgical grade silicon may be purified by the acid extraction technique because of the segregation of impurities at grain boundaries during the solidification of the melt in the manufacturing process. The partial purification of pulverized metallurgical silicon by refluxing with acids has been investigated in detail using aqua regia, hydrochloric acid, and an equivolume mixture of sulfuric acid and nitric acid. Aqua regia is most effective, and the extent of removal of metallic impurities under atmospheric pressure has been determined as a function of the duration of refluxing. Although more than 80% of metallic impurities can be removed, the dissolution of impurities is a slow process. The rate of dissolution may be increased many folds by carrying out the aqua regia extraction in a closed system at high temperatures under pressure.

This publication has 0 references indexed in Scilit: