A novel technique was developed to remove impurities from crude lead by vacuum distillation.The thermodynamics on vacuum distillation refining process of crude lead was studied by means of saturated vapor pressure of ...A novel technique was developed to remove impurities from crude lead by vacuum distillation.The thermodynamics on vacuum distillation refining process of crude lead was studied by means of saturated vapor pressure of main components of crude lead,separation coefficients and vapor-liquid equilibrium composition of Pb-i(i stands for an impurity) system at different temperatures.The behaviors of impurities in the vacuum distillation refining process were investigated.The results show that the vacuum distillation should be taken to obtain lead from crude lead,in which Zn,As and partial Sb are volatilized at lower temperature of 923-1023 K.Lead is distilled from the residue containing Cu,Sn,Ag and Bi at higher temperature of 1323-1423 K,but the impurity Bi is also volatilized along with lead and cannot be separated from lead.展开更多
The removal of impurity phosphorus from metallurgical grade silicon is one of the major problems on purification of metallurgical grade silicon for solar grade silicon preparation. The thermodynamics on vacuum refinin...The removal of impurity phosphorus from metallurgical grade silicon is one of the major problems on purification of metallurgical grade silicon for solar grade silicon preparation. The thermodynamics on vacuum refining process of the metallurgical grade silicon was studied via separation coefficient of impurity phosphorus in the metallurgical grade silicon and vapor-liquid equilibrium composition diagram of Si-P binary alloy at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined. The results show that the vacuum distillation should be taken to obtain silicon with less than 10-7 P,and the impurity phosphorus is volatilized easily by vacuum distillation in thermodynamics. Phosphorus is distilled from the molten silicon and concentrated in vapor phase.展开更多
The kinetics on vacuum refining process of metallurgical grade silicon was studied using maximum evaporation rate,critical pressure and mean free path of phosphorus in the metallurgical grade silicon at different temp...The kinetics on vacuum refining process of metallurgical grade silicon was studied using maximum evaporation rate,critical pressure and mean free path of phosphorus in the metallurgical grade silicon at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined in detail. The results show that the fractional vacuum distillation should be taken to obtain silicon with high purity. Impurity phosphorus volatilize with the maximum evaporation rate of 1.150×105- 1.585×106 g/(cm2·min) in the temperature range of 1 073-2 173 K and the pressure below 2.1 Pa. Because the value of ωmax,P is at least 108 times of ωmax,Si,Si hardly evaporates and remains in the residual,which indicates that phosphorus can be removed from metallurgical grade silicon(MG-Si) completely.展开更多
基金Project (2012CB722803) supported by the National Basic Research Program of ChinaProject (U1202271) supported by the National Natural Science Foundation of China
文摘A novel technique was developed to remove impurities from crude lead by vacuum distillation.The thermodynamics on vacuum distillation refining process of crude lead was studied by means of saturated vapor pressure of main components of crude lead,separation coefficients and vapor-liquid equilibrium composition of Pb-i(i stands for an impurity) system at different temperatures.The behaviors of impurities in the vacuum distillation refining process were investigated.The results show that the vacuum distillation should be taken to obtain lead from crude lead,in which Zn,As and partial Sb are volatilized at lower temperature of 923-1023 K.Lead is distilled from the residue containing Cu,Sn,Ag and Bi at higher temperature of 1323-1423 K,but the impurity Bi is also volatilized along with lead and cannot be separated from lead.
基金Project(50674050) supported by the National Natural Science Foundation of ChinaProject(2006BAE01B08) supported by Sustentation Project of Science and Technology of ChinaProject(20060674004) supported by the Doctorial Programs Foundation of Ministry of Education of China.
文摘The removal of impurity phosphorus from metallurgical grade silicon is one of the major problems on purification of metallurgical grade silicon for solar grade silicon preparation. The thermodynamics on vacuum refining process of the metallurgical grade silicon was studied via separation coefficient of impurity phosphorus in the metallurgical grade silicon and vapor-liquid equilibrium composition diagram of Si-P binary alloy at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined. The results show that the vacuum distillation should be taken to obtain silicon with less than 10-7 P,and the impurity phosphorus is volatilized easily by vacuum distillation in thermodynamics. Phosphorus is distilled from the molten silicon and concentrated in vapor phase.
基金Project(50674050) supported by the National Natural Science Foundation of ChinaProject(2006BAE01B08) supported by the Sustentation Project of Science and Technology of ChinaProject(20060674004) supported by Doctorial Programs Foundation of Ministry of Education of China.
文摘The kinetics on vacuum refining process of metallurgical grade silicon was studied using maximum evaporation rate,critical pressure and mean free path of phosphorus in the metallurgical grade silicon at different temperatures. The behaviors of impurity phosphorus in the vacuum distillation process were examined in detail. The results show that the fractional vacuum distillation should be taken to obtain silicon with high purity. Impurity phosphorus volatilize with the maximum evaporation rate of 1.150×105- 1.585×106 g/(cm2·min) in the temperature range of 1 073-2 173 K and the pressure below 2.1 Pa. Because the value of ωmax,P is at least 108 times of ωmax,Si,Si hardly evaporates and remains in the residual,which indicates that phosphorus can be removed from metallurgical grade silicon(MG-Si) completely.