Research On The Influence Of Electromagnetic Suspension Strength On The Removal Of Phosphorus From Metallurgical Grade Silicon And Ferrosilicon

Solar grade silicon(SoG-Si)is a kind of photoelectric conversion material,in which the high content of silicon element affects the photoelectric conversion efficiency,and it is found that the removal of phosphorus is difficult in the preparation process.Electromagnetic levitation(EML)refining technology is a flawless,non-contact,non-contaminating technology for melts.It plays an important role in refining metals and is a good means for the study of the mechanism of dephosphorization of ferrosilicon and metallurgical grade silicon(MG-Si).Therefore,the research aims to provide new ideas for the removal of phosphorus impurities in SoG-Si production processes.Meanwhile,promoting it lays the foundation for the theory of EML.The paper combines theoretical study,numerical simulation study and experimental study to research the effect of electromagnetic levitation intensity on the removal of phosphorus from MG-Si and ferrosilicon.The main results are as follows.(1)Theoretical study on dephosphorization of MG-Si and ferrosilicon under electromagnetic levitation conditions is carried out.It is found that the structure of the spiral induction coil,the nature of the sample and the current intensity are the main factors affecting the stable levitation of the sample.The dephosphorization kinetics is analyzed.The phosphorus element in the sample is removed by direct volatilization.When the refining temperature rises,the liquid phase mass transfer coefficient and the apparent rate constant of the phosphorus element in the sample increase.(2)The EML intensity simulation study is carried out.The finite element method is used to establish the droplet inductance model,which mainly simulates the influence of the spiral induction coil structure,current intensity and droplet quality on the droplet levitation intensity.The simulation results show: The related parameters parameters of the droplet magnetic field strength and electromagnetic force increase with the increase of current intensity and droplet quality,but the distribution of the two is not affected by the current intensity and droplet quality change.And the related parameters of the droplet magnetic field strength and electromagnetic force arepositively correlated with the turn number of the spiral induction coil,and negatively correlated with the cone angle and diameter.The direction of the electromagnetic force received by the droplet is always directed to the center of the sphere and is not affected by changes in the spiral induction coil,current intensity and droplet quality.Predicting the best spiral induction coil design,the specific parameters are: coil diameter is 6mm,cone angle is 0°,turn number of levitation coil is 3,turn number of stable coil is 2.(3)The dephosphorization experimental research of ferrosilicon and MG-Si is carried out.The best spiral induction coil predicted by the simulation results was verified through experimental research.The best sample quality is determined to be0.6g.Under the optimal levitation parameters,the relationship between the current intensity and the dephosphorization rate of ferrosilicon and MG-Si is tested.The results show that: 1)The current intensity is proportional to the refining temperature.Properly increasing the refining temperature and prolonging the refining time contribute to dephosphorization of ferrosilicon and MG-Si;2)Considering factors such as droplet levitation stability,dephosphorization rate and cost,the optimal refining temperature and time parameters of ferrosilicon dephosphorization are determined to be 1750? and 45 min,and the dephosphorization rate is 70.6%;the optimal refining temperature and time parameters of MG-Si dephosphorization are determined to be 1750? and 35 min,and the dephosphorization rate is 70%.