Thermodynamic evaluation of phosphorus removal within Metallurgical Grade Silicon by fractional melting process

摘要

In the current study,a new method for the purification of metallurgical grade silicon (MG-Si),fractional melting process,was proposed and discussed.The proposed method combines the phosphorus segregation behavior between solid silicon and Al-Si melt to removal phosphorus.The segregation coefficient of phosphorus between solid silicon and Al-Si melt decreases with the drop of temperature,which demonstrate the thermodynamic feasibility of silicon purification within Al-Si system.By alloying MG-Si with Al,phosphorus could segregate into the Al-Si eutectics from MG-Si,and form a specific Al-Si-Ca-P impurity phase.Content of phosphorus in the impurity phase was relatively stable.After three times refining,the content of phosphorus is reduced to 0.68×10-6 with the removal fraction of 94.89％.The recovery of refined silicon is increased with the Si proportion increased.