Slag Treatment Followed by Acid Leaching as a Route to Solar-Grade Silicon

Meteleva-Fischer, Yulia V.; Yang, Yongxiang; Boom, R.; Kraaijveld, B.; Kuntzel, H.

doi:10.1007/s11837-012-0383-4

Cited by 37 publications

(17 citation statements)

References 18 publications

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“…This is a very positive refining effect, because the impurity phase accumulates phosphorus. The affinity of phosphorus to the FeSiaTi phase was also observed in the study of a slag treatment of MG-Si(Meteleva-Fischer et al, 2012c). According to the ratio of A'P/A'TÍ~0-45(Table 1), not all the phosphorus is present in that phase.…”

mentioning

confidence: 71%

Microstructure of metallurgical grade silicon and its acid leaching behaviour by alloying with calcium

Meteleva-Fischer

Yang

Boom

et al. 2013

Mineral Processing and Extractive Metallurgy

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The efficiency of acid leaching as a low-cost refining method of metallurgical grade silicon (MG-Si) is determined by the microstructure of silicon. In the present work the influence of microstructure of MG-Si on its leaching behaviour was studied in order to explore the potential of this method in achieving solar grade purity of silicon. The microstructure of silicon was modified by alloying with 3-10 wt-% of calcium, and the influence of the concentration of alloying elements and the solidification conditions on the leaching efficiency was evaluated. It was shown that the major impurity and its location determine the preferred leaching agent. A mechanism of removal of metallic and non-metallic impurities was proposed. Control of the alloying process resulted in enhanced removal of the major part of the impurities, including phosphorus.

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confidence: 71%

Microstructure of metallurgical grade silicon and its acid leaching behaviour by alloying with calcium

Meteleva-Fischer

Yang

Boom

et al. 2013

Mineral Processing and Extractive Metallurgy

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“…For instance, by using slag refining technology in the same manner as is used in steel production, some impurities can be removed directly from molten Si into the slag phase ( Figure 3 a). [45][46][47][48][49] The impurities in MG-Si can also be removed to the vapor phase under oxidizing conditions by electron beam (EB) or plasma irradiation (Figure 3 b). [46,[50][51][52][53][54] Effective directional solidification refining using Si-Al melts and other Si-metal alloys as extraction solvents in the liquid .…”

Section: Refining Of Metallurgical-grade Simentioning

confidence: 99%

“…Schematic illustration of the processes for upgrading Si under development:[45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] a) slag process, b) plasma and EB process, and c) solidification refining from the Si-Al melt.…”

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confidence: 99%

Processes for Production of Solar‐Grade Silicon Using Hydrogen Reduction and/or Thermal Decomposition

2014

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High‐purity Si used for photovoltaic applications, namely, solar‐grade Si (SOG‐Si), is commercially manufactured using the Siemens process. Although the present levels of supply satisfy the demand, there can potentially be a shortage of SOG‐Si in the long term. To overcome the low productivity of the Siemens process, various types of SOG‐Si production/purification processes have been developed as post‐Siemens processes. Some processes are under development as new commercial processes. These processes can be classified into the following three categories: (1) hydrogen reduction and/or thermal decomposition of silane‐based gases in improved Siemens‐based processes, (2) metallothermic reduction of silicon halides by Zn or Al, and (3) upgrading metallurgical‐grade Si by employing metallurgical purification methods. This paper presents a review of various types of SOG‐Si production processes, particularly those based on the hydrogen reduction and/or thermal decomposition of halides and silane‐based gases. These processes are classified on the basis of Si compounds used and the reaction types; further, the features of these processes are also analyzed. Future prospects for the development of new high‐purity Si production process are also presented.

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“…The aim of this process is to cost-effectively refine metallurgical-grade Si by slag treatment, acid leaching, and directional solidification. [11][12][13] However, UMG has a relatively small market share at present because of problems with purity control. [8,14] Various attempts have been made to optimize the present technologies to improve energy efficiency and productivity and to reduce cost.…”

Section: Introductionmentioning

confidence: 99%

The Role of Granule Size on the Kinetics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

Yang

Yasuda

Hagiwara

et al. 2015

Metall Mater Trans B

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As a fundamental study to develop a new process for producing solar-grade silicon, the effect of granule size on the kinetics of the electrochemical reduction of SiO 2 granules in molten CaCl 2 was investigated. SiO 2 granules with different size ranges were electrolyzed in molten CaCl 2 at 1123 K (850 °C). The reduction kinetics was evaluated on the basis of the growth rate of the reduced Si layer and the behavior of the current during electrolysis. The results indicated that finer SiO 2 granules are more favorable for a high reduction rate because the contact resistance between the bottom Si plate and the reduced Si particles is small and the diffusion of O 2ions in CaCl 2 inside the porous Si shell is easy. Electrolysis using SiO 2 granules less than 0.1 mm in size maintained a current density of no less than 0.4 A cm-2 within 20 min, indicating that the electrochemical reduction of fine SiO 2 granules in molten CaCl 2 has the potential of becoming a high-yield production process for solargrade silicon.

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Slag Treatment Followed by Acid Leaching as a Route to Solar-Grade Silicon

Cited by 37 publications

References 18 publications

Microstructure of metallurgical grade silicon and its acid leaching behaviour by alloying with calcium

Microstructure of metallurgical grade silicon and its acid leaching behaviour by alloying with calcium

Processes for Production of Solar‐Grade Silicon Using Hydrogen Reduction and/or Thermal Decomposition

The Role of Granule Size on the Kinetics of Electrochemical Reduction of SiO2 Granules in Molten CaCl2

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