Calcium-silicate based slag for treatment of molten silicon

摘要

A method for making solar grade silicon from metallurgical grade silicon is accomplished by treating a calcium silicate based slag with ferrosilicon in the first vessel so as to obtain a purification of the calcium silicate based slag. In a second vessel, the purified calcium based silicate slag is used to treat metallurgical grade silicon in order to obtain a solar grade silicon. The purification of calcium silicate based slag in the first vessel is accomplished to reduce phosphorous to a level of less than 3 ppmw.