Boron removal from metallurgical-grade silicon(MG-Si) using CaO–SiO2 slag was studied by employing a medium-frequency electromagnetic induction furnace.The relationship between the optical basicity(K)of the CaO–SiO2...Boron removal from metallurgical-grade silicon(MG-Si) using CaO–SiO2 slag was studied by employing a medium-frequency electromagnetic induction furnace.The relationship between the optical basicity(K)of the CaO–SiO2 slag and the distribution coefficient of boron(LB) was investigated.Consequently, the local minimum and maximum LBvalues of 0.72 and 1.58 are obtained when K = 0.56 and K = 0.71, respectively.The boron content in MG-Si decreases gradually with refinement time increasing, down to a minimum value of4.73 9 10-6.The controlling step in the removal of boron from MG-Si is not the chemical reaction at the interface of the slag and silicon.Instead, the controlling step is a diffusion mass transfer, in which boron impurities diffuse from molten silicon to the interface of the slag and silicon,or B2O3 formed by the chemical reaction diffuses from the slag–silicon interface to molten slag.展开更多
The removal of boron impurity from metallurgical-grade silicon for solar cell application in slag system of CaO-SiO_2 is investigated.The experiments are conducted in an electromagnetic induction furnace which is used...The removal of boron impurity from metallurgical-grade silicon for solar cell application in slag system of CaO-SiO_2 is investigated.The experiments are conducted in an electromagnetic induction furnace which is used to heat. The distribution coefficient of boron(L_B)between slag and silicon phase is particularly examined in terms of the optical basicity of slag.With the increase of optical basicity,L_B increases to a local maximum value of 1.58 when the optical basicity is 0.71 after getting to the minimum value of 0.72 when the optical basicity is 0.56.In that above optical basicity of 0.71,L_B decrease sharply which indicates that increasing the basicity of slag is not always effective in boron removal from silicon.展开更多
The temperature and velocity distribution of melting pool fields is very important effect to the silicon purification in vacuum induction furnace.A numerical model for the electromagnetic-thermal-hydrodynamic coupling...The temperature and velocity distribution of melting pool fields is very important effect to the silicon purification in vacuum induction furnace.A numerical model for the electromagnetic-thermal-hydrodynamic coupling fields have been developed by using the finite element method(FEM)and a 2D numerical simulation for electromagnetic、 temperature and velocity fields of metallurgical-grade silicon melting in vacuum induction furnace were performed with a software Multi-physics Comsol 3.5a in this paper.The results showed that the temperature field was dependent observably on input power of coils and induction heating times and the maximum temperature gradient in melting pool was 215K in holding time.With the silicon molted gradually a clockwise vortex was come into being for electromagnetic stirring in the smelting poor.The variation of velocity field in melting silicon is mainly influenced with the change of the current intensity and power frequency.The numerical predications of temperature distribution are in good agreement with experiments.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51461027 and 51104080)
文摘Boron removal from metallurgical-grade silicon(MG-Si) using CaO–SiO2 slag was studied by employing a medium-frequency electromagnetic induction furnace.The relationship between the optical basicity(K)of the CaO–SiO2 slag and the distribution coefficient of boron(LB) was investigated.Consequently, the local minimum and maximum LBvalues of 0.72 and 1.58 are obtained when K = 0.56 and K = 0.71, respectively.The boron content in MG-Si decreases gradually with refinement time increasing, down to a minimum value of4.73 9 10-6.The controlling step in the removal of boron from MG-Si is not the chemical reaction at the interface of the slag and silicon.Instead, the controlling step is a diffusion mass transfer, in which boron impurities diffuse from molten silicon to the interface of the slag and silicon,or B2O3 formed by the chemical reaction diffuses from the slag–silicon interface to molten slag.
基金Item Sponsored by the National Natural Science Foundation of China[u1137601,51104080]
文摘The removal of boron impurity from metallurgical-grade silicon for solar cell application in slag system of CaO-SiO_2 is investigated.The experiments are conducted in an electromagnetic induction furnace which is used to heat. The distribution coefficient of boron(L_B)between slag and silicon phase is particularly examined in terms of the optical basicity of slag.With the increase of optical basicity,L_B increases to a local maximum value of 1.58 when the optical basicity is 0.71 after getting to the minimum value of 0.72 when the optical basicity is 0.56.In that above optical basicity of 0.71,L_B decrease sharply which indicates that increasing the basicity of slag is not always effective in boron removal from silicon.
基金Item Sponsored by the NSFC project (51066003u1137601) +1 种基金National science & technology support plan project (2011BAE03B01) Scientific Research Foundation Project (2010Y408) of Yunnan Province Education Department
文摘The temperature and velocity distribution of melting pool fields is very important effect to the silicon purification in vacuum induction furnace.A numerical model for the electromagnetic-thermal-hydrodynamic coupling fields have been developed by using the finite element method(FEM)and a 2D numerical simulation for electromagnetic、 temperature and velocity fields of metallurgical-grade silicon melting in vacuum induction furnace were performed with a software Multi-physics Comsol 3.5a in this paper.The results showed that the temperature field was dependent observably on input power of coils and induction heating times and the maximum temperature gradient in melting pool was 215K in holding time.With the silicon molted gradually a clockwise vortex was come into being for electromagnetic stirring in the smelting poor.The variation of velocity field in melting silicon is mainly influenced with the change of the current intensity and power frequency.The numerical predications of temperature distribution are in good agreement with experiments.
