Diffusion and mass transfer of boron in molten silicon during slag refining process of metallurgical grade silicon

Wu, Jijun; Wang, Fanmao; Chen, Zhengjie; Ma, Wenhui; Li, Yanlong; Yang, Bin; Dai, Yongnian

doi:10.1016/j.fluid.2015.06.040

Cited by 12 publications

(4 citation statements)

References 20 publications

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“…According to the boundary layer theory of convective mass transfer, the convection mass perpendicular to the phase interface was 0 at x = 0, where the mass transfer feature is steady-state molecular diffusion, so the following relation is obtained …”

Section: Resultsmentioning

confidence: 99%

“…As the alloy droplet falls in the slag, the change of B content in droplet with time is related to the surface area of droplet and the mass transfer coefficient in the dynamic process ( k d ), as shown in . is the integral form of …”

Section: Resultsmentioning

confidence: 99%

“…28-2 is the integral form of 28-1. 38 w[B] 0 and w[B] t are the mass fraction of B in the droplet at the starting point and the ending point of its fall, respectively.…”

Section: Calculation and Analysis Of Droplet Motormentioning

confidence: 99%

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Novel Application of Electroslag Remelting Refining in the Removal of Boron and Phosphorus from Silicon Alloy for Silicon Recovery

Qian

Sun

Wang

et al. 2021

ACS Sustainable Chem. Eng.

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With the shortage of high-grade silicon (Si) feedstock due to the rapid development of photovoltaic, electronic information, and organic Si industries, there is an increasing demand to recycle Si waste economically and efficiently. However, the deep removal of B and P from Si has always been a significant challenge for Si waste recycling. A novel application of electroslag remelting (ESR) refining has been developed to remove B and P for the purification and recovery of Si. In addition, industrial tests were performed to recover the diamond wire saw Si powder. The design principle is put forward for the Si alloy electroslag system. A new 35% CaO−30% CaF 2 −17.5% Al 2 O 3 −17.5% SiO 2 electroslag applicable for Si alloy ESR is designed to meet both physical and impurity removal requirements. Furthermore, the conductivity (2.67 Ω −1 •cm −1 ), density (2.97 g/cm 3 ), and viscosity (0.05 Pa•s) meet the requirements of ESR. The dynamic refining process of Si alloy passing through the slag layer in the droplet form is the core of ESR refining, and it is found that more than 80% of B and P removal is achieved in the dynamic refining process of the droplet penetration slag. In order to understand the dynamic refining process, the mathematical model of droplet movement and impurity removal model are proposed to study the droplet movement behavior in slag and the competitive influence mechanism of multiple parameters on B removal efficiency during the dynamic refining process. Mathematical models and experimental results show that there is an ultimate velocity of droplet entry into the slag, which increases linearly with the growth of droplet size under the same slag condition. In addition, the specific surface area of the droplet plays a dominant role in the removal of B. The successful industrial experiments of Si alloy ESR prove that the design principle of the Si alloy electroslag system and the size control mechanism of Si alloy are feasible in this work. The removal efficiency of B and P reached 80 and 65%, respectively, within 30 min. It is also believed that ESR will have an application in purification and recovery of Si waste.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Novel Application of Electroslag Remelting Refining in the Removal of Boron and Phosphorus from Silicon Alloy for Silicon Recovery

Qian

Sun

Wang

et al. 2021

ACS Sustainable Chem. Eng.

Self Cite

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“…Polycrystalline silicon is one of the best materials for application in photovoltaic energy conversion . Several processes exist for the production of high-purity silicon, such as the Siemens process (Ramos et al, 2013;Bye and Ceccaroli, 2014;Belstito et al, 2016), metallurgical processing (Wu et al, 2015;Khader and Sweilam, 2016;Liu et al, 2016), fluidized bed processing (Ramos et al, 2015;Ren et al, 2015), zinc reduction Nie et al, 2015), and carbothermal reduction of silicon dioxide (Meyer et al, 2014;Ni et al, 2014). The Siemens process is the primary technology for polycrystalline production (Moon et al, 2014;Ekstrom et al, 2016;Ko et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Equilibrium Concentrations of SiHCl3 and SiCl4 in SiCl4–H2 System for Hydrogenation of SiCl4 to SiHCl3

Zhou¹,

Fand²,

Li³

et al. 2017

J. Chem. Eng. Japan / JCEJ

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The equilibrium concentrations of SiHCl 3 and SiCl 4 in the SiCl 4 -H 2 system are investigated on the basis of thermodynamic data for the corresponding pure compositions under speci ed thermodynamic parameters. Eight independent reactions in the SiCl 4 -H 2 system for hydrogenation of SiCl 4 to SiHCl 3 are obtained. Furthermore, the factors (such as temperature, pressure, and feed mole ratio) in uencing the equilibrium concentrations of SiCl 4 and SiHCl 3 are studied. Diagrams of the equilibrium concentrations of SiCl 4 and SiHCl 3 as a function of temperature, pressure, and feed mole ratio are presented. Finally, the optimal thermodynamic conditions in the SiCl 4 -H 2 system for hydrogenation of SiCl 4 to SiHCl 3 are determined to be 1,100°C, 0.3 MPa, and a feed molar ratio of 4. Under these conditions, the conversion ratio of SiCl 4 to SiHCl 4 is about 25%, compared to a value of less than 20% in actual production.

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An Innovative Method to Calculate the Boundary Layer Thickness of the Gas–Slag Interface

Wang

2022

Metall Mater Trans B

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Diffusion and mass transfer of boron in molten silicon during slag refining process of metallurgical grade silicon

Cited by 12 publications

References 20 publications

Novel Application of Electroslag Remelting Refining in the Removal of Boron and Phosphorus from Silicon Alloy for Silicon Recovery

Novel Application of Electroslag Remelting Refining in the Removal of Boron and Phosphorus from Silicon Alloy for Silicon Recovery

Equilibrium Concentrations of SiHCl<sub>3</sub> and SiCl<sub>4</sub> in SiCl<sub>4</sub>–H<sub>2</sub> System for Hydrogenation of SiCl<sub>4</sub> to SiHCl<sub>3</sub>

An Innovative Method to Calculate the Boundary Layer Thickness of the Gas–Slag Interface

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