Extraction of phosphorus from metallurgical grade silicon using a combined process of Si-Al-Ca solvent refining and CaO-CaF2 slag treatment

Zhang, Chentong; Lai, Huixian; Zhang, Yaohao; Sheng, Zhilin; Li, Jintang; Xing, Pengfei; Luo, Xuetao

doi:10.1016/j.seppur.2019.115954

Cited by 17 publications

(4 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Equations [1] and [2] show the relationship between the effective separation coefficient of impurities and the rotation rate of mold. The diffusion coefficient D is greatly affected by temperature and changes constantly during the whole crystallization process.…”

Section: Separation Behavior Of Impurities In Silicon During Rotation...mentioning

confidence: 99%

“…Metallurgical refining and purification technology has been widely developed due to its advantages of simplified process, low investment cost, and less energy consumption. [1][2][3][4][5][6][7][8][9][10][11][12][13] Based on the oxidation/reduction properties, [2,3] the separation coefficient of impurities, [4][5][6][7][8][9][10] and saturated vapor pressure [11][12][13] and other separation properties, the present metallurgical purification process generally adopts a variety of sequentially combined operations to separate impurities step by step. With the global trend of carbon neutrality, the rapid development of solar photovoltaic industry has raised new challenges to the preparation technology and equipment of solar grade polysilicon (SoG-Si).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Simulation of Flow Field Optimizing the Rotating Segregation Purification of Silicon for SoG-Si

Shang

Qian

Wang

et al. 2022

Metall Mater Trans B

Self Cite

View full text Add to dashboard Cite

In order to improve the preparation efficiency of high-purity silicon, a new method of rotary segregation purification has been developed to prepare polysilicon. Numerical simulation based on ANSYS19.0 software and water model experiments were used to study the distribution of flow field and optimize the impurity removal process. A numerical simulation model suitable for rotating interface is established. The simulation result is in good agreement with the water model experiment. A vortex flow is found in the middle of the mold when the mold insertion depth is 90 mm. The vortex is conducive to the thinning of the impurity enrichment layer at the solid-liquid interface. With the mold insertion depth increases from 90 to 170 mm, two vortex flows appear in the middle and bottom of the mold, respectively. Moreover, setting the mold rotation rate at 100 rpm can contribute to a more stable flow field and a higher melt flow velocity. When the diffusion layer thickness is less than 0.1 mm, the impurity segregation coefficient can approach close to its equilibrium segregation coefficient, indicating that impurity segregation be effectively enhanced by increasing the rotation rate of mold, strengthening the effect of solidification rate and increasing the rotational speed. Industrial tests were carried out at the 100 kg level. The result shows that the rotary segregation method and equipment can achieve the removal of very low impurity in silicon (99.999 pct), and SoG-Si (99.9999 pct) was obtained. This method provides a new way for silicon purification, and it is believed that better results can be obtained through continuous improvement.

show abstract

Section: Separation Behavior Of Impurities In Silicon During Rotation...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Flow Field Optimizing the Rotating Segregation Purification of Silicon for SoG-Si

Shang

Qian

Wang

et al. 2022

Metall Mater Trans B

Self Cite

View full text Add to dashboard Cite

show abstract

“…[19] Nowadays, up to 0.2 ppmw of phosphorus in Si is accepted as the limit for SoG-Si production, which could be reduced in the future if higher efficiencies are required. [20] Many research works have been carried out in the recent years on removal of P from Si, [8,9,[21][22][23][24][25][26][27][28] and many of them were focused on vacuum refining. [1,4,5,12,[29][30][31][32][33][34][35][36][37] According to literature and our previous works, vacuum refining of Si is one of the most efficient and clean methods for the complete removal of phosphorus from Si.…”

Section: Introductionmentioning

confidence: 99%

On the Phosphorus Evaporation from Liquid Silicon by Knudsen Effusion Mass Spectrometry

Hoseinpur

Sergeev

Müller

et al. 2022

Metall Mater Trans B

View full text Add to dashboard Cite

Silicon refining for solar applications is intensively on demand, and removal of phosphorus from Si is one of the most challenging steps. Evaporation of P from liquid Si in a vacuum refining process is the most efficient method for P removal from Si, and this research deals with the insight mechanisms of P evaporation from liquid Si. In this research, the gaseous species evaporating from the dilute liquid solutions of phosphorus in silicon were studied experimentally, and it was shown that phosphorus evaporates in the form of P, P2, P4, P3, SiP, Si2P, Si3P, and SiP2 at elevated temperatures. Except P and P2, the other molecules were detected experimentally for the first time, and Si3P was detected as a new compound in the gas phase. Knudsen effusion mass spectrometry technique was applied to characterize the evaporation of phosphorus from liquid Si samples containing 100, 1250, and 3000 ppmw phosphorus. The evaporation of phosphorus from liquid Si was studied by isothermal and polythermal experiments, up to 1840 °C. The vapor pressures of various P-containing molecules (P, P2, P4, SiP, Si2P) at 1442 °C were measured as a function of phosphorus fraction in liquid silicon. Results indicated that a major part of the phosphorus evaporates in the form of silicon phosphides and P4, especially when the sample temperature exceeds 1750 °C. When initial phosphorus was 100 ppmw, about 71 pct of phosphorus evaporation was by means of silicon phosphides and P4. The mechanisms of phosphorus evaporation from liquid Si are proposed, which depend on the melt composition and temperature. It occurs through phosphorus species evaporation independently or via the decomposition of transient silicon phosphides at the surface or through the direct evaporation of silicon phosphides at the melt surface.

show abstract

“…In the secondary re ning of industrial silicon, slag system is the key to determine the removal e ciency [13][14][15] . Common slag systems include Na 2 O-SiO 2 [16] , Si-Al-Ca [17] , CaO-SiO 2 [13] , SiO 2 -Al 2 O 3 [18] etc.…”

Section: Introductionmentioning

confidence: 99%

Study on the Composition and Interface of Waste Silicon Slag After Secondary Refining

Qiao

Liang

Zhao

et al. 2021

Silicon

View full text Add to dashboard Cite

Silicon slag is a secondary re ning byproduct from industrial silicon. The content of industrial silicon in silicon slag is about 20% , which has extremely high economic value. To better achieve the recovery and reuse of industrial silicon slag, the morphology of industrial silicon slag, the occurrence state of elements and especially the interfacial structure between silicon and slag were deeply studied in this paper. The macro and micro morphology and surface composition distribution of the silicon slag were observed by microscope, SEM-EDS and Raman spectroscopy. The phase and composition of the silicon slag were analyzed by XRF and XRD. The results showed that the purity of silicon particles in silicon slag is high up to 99% . The size and shape of silicon in silicon slag were quite different. The interface between silicon and slag is clear and there is no obvious two-phase transition zone, which is conducive to the recycling of silicon. The crushing behavior of silicon slag under different pressure was investigated. These results provide a theoretical basis for further crushing silicon slag and recovering silicon particles. When silicon slag was crushed under certain pressure, the fracture surface of large-size silicon was mostly siliconsilicon interface. Therefore, in order to realize the complete dissociation of slag and silicon, the size of the crushing particle needs to be small enough. In this paper, the physical and chemical properties of industrial silicon slag were studied, which provides a theoretical basis for the e cient separation and recovery of silicon in the slag.

show abstract

Extraction of phosphorus from metallurgical grade silicon using a combined process of Si-Al-Ca solvent refining and CaO-CaF2 slag treatment

Cited by 17 publications

References 40 publications

Numerical Simulation of Flow Field Optimizing the Rotating Segregation Purification of Silicon for SoG-Si

Numerical Simulation of Flow Field Optimizing the Rotating Segregation Purification of Silicon for SoG-Si

On the Phosphorus Evaporation from Liquid Silicon by Knudsen Effusion Mass Spectrometry

Study on the Composition and Interface of Waste Silicon Slag After Secondary Refining

Contact Info

Product

Resources

About