Dephosphorization of Metallurgical-Grade Silicon by Electromagnetic Levitation

In this work, a dynamic model was established for the dephosphorization of metallurgical grade silicon by levitation refining. Particular emphasis was placed on the transport behavior of phosphorus in the liquid boundary layer, then at the melt surface and finally within the gas phase surrounding the levitated droplet. Within the melt boundary layer, and at the droplet surface, temperature was the controlling factor affecting phosphorus behavior. Within the gas phase, the controlling factors were temperature and gas velocity with temperature showing a more pronounced effect on the phosphorus mass transfer coefficient than gas velocity. The dynamic model shows that the dephosphorization of MG-Si was controlled by phosphorus diffusion within the gas phase. The values calculated from the model for the mass transfer coefficient were in good agreement with dephosphorization data obtained from levitation experiments conducted with metallurgical grade silicon. This work can provide a good foundation for application of electromagnetic levitation technology to the refining of metallurgical grade silicon.