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

A novel method of combined Si-Al solvent refining with CaCl 2 -CaF 2 -CaO molten salt treatment for phosphorus removal from metallurgical-grade silicon was investigated. With the mass ratio of salt (45 wt.%CaCl 2 –45 wt.%CaF 2 –10 wt.%CaO) to the alloy (phosphorus-doped Al-Si) being 1:1, phosphorus-rich phases of Ca 3 P 2 and CaAl 2 Si 2 -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%.