Low-temperature enhancement in the extraction of phosphorus from metallurgical-grade silicon by simultaneously re-constructing phosphorus-rich phases of Ca₃P₂ and CaAl₂Si₂-P

Abstract

A novel method of combined Si-Al solvent refining with CaCl2-CaF2-CaO molten salt treatment for phosphorus removal from metallurgical-grade silicon was investigated. With the mass ratio of salt (45 wt.%CaCl2–45 wt.%CaF2–10 wt.%CaO) to the alloy (phosphorus-doped Al-Si) being 1:1, phosphorus-rich phases of Ca3P2 and CaAl2Si2-P were successfully reconstructed at 1250 °C for 1 h. After acid leaching, phosphorus content decreased from 3 wt.% to 0.24 wt.%, corresponding to a phosphorus removal rate of 91.95%.