Effects of Slag Treatment Conditions on Boron Removal from Metallurgical Silicon by United Gas-Slag Refining Technology

Abstract

Impurities in industrial silicon strongly affect the performance and use value of silicon products, so that raw industrial silicon must be re ned to reduce the impurity content and improve its quality. In this work, the effect of the conditions of the re ning process on the removal of impurities was studied. The slag agent and industrial silicon powder are uniformly mixed, and a mixed gas of Ar-H 2 O-O 2 is blown into the melt for re ning experiments when the set re ning temperature is reached. 3% mass fraction highpurity boron powder is pre-melted into industrial silicon raw materials to prepare Si-3%B alloy raw materials, and then the Si-3%B alloy raw materials are re ned and pickled with CaO-SiO 2 -CaCl 2 . The composition of the slag agent, the slag-agent-to-silicon mass ratio, the re ning time, and the re ning temperature conditions were explored, and the best e ciency of boron removal was found to be 96.77%, with the boron content in silicon decreased from 22 ppmw to the lowest value of 0.6 ppmw. The boron content in re ned silicon shows a clear decrease, demonstrating that slag-making gas blowing re ning is effective for the removal of impurities in industrial silicon.