Purification of metallurgical silicon using iron as impurity getter, part II: Extent of silicon purification

Esfahani, Shaghayegh; Barati, Mansoor

doi:10.1007/s12540-011-6020-x

Cited by 69 publications

(16 citation statements)

References 12 publications

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“…For instance, Ni, which was used for the electrode shown in Figure 2 g, is such a candidate: 30 000 ppm of Ni is acceptable in primary Si ( Table 1). Considering that Al, Cu, Sn, and Fe have previously been investigated as solidifying solvents for refining metallurgical-grade Si, [44][45][46][47][48][49][50] combining our method with solidification could be an effective solution.…”

Section: Feasibility For Sog-si Productionmentioning

confidence: 99%

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon

et al. 2013

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The direct electrolytic reduction of solid SiO2 is investigated in molten CaCl2 at 1123 K to produce solar‐grade silicon. The target concentrations of impurities for the primary Si are calculated from the acceptable concentrations of impurities in solar‐grade silicon (SOG‐Si) and the segregation coefficients for the impurity elements. The concentrations of most metal impurities are significantly decreased below their target concentrations by using a quartz vessel and new types of SiO2‐contacting electrodes. The electrolytic reduction rate is increased by improving an electron pathway from the lead material to the SiO2, which demonstrates that the characteristics of the electric contact are important factors affecting the reduction rate. Pellet‐ and basket‐type electrodes are tested to improve the process volume for powdery and granular SiO2. Based on the purity of the Si product after melting, refining, and solidifying, the potential of the technology is discussed.

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Section: Feasibility For Sog-si Productionmentioning

confidence: 99%

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon

et al. 2013

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“…Most impurities, including those with high segregation coefficients in Si such as P and B, can be more effectively removed by this process compared with ordinary directional solidification. In addition to the Si-Al solvent, other Si-based solvents such as Si-Cu [17], Si-Ni [18], Si-Na [19], Si-Fe [20,21], Si-Al (-Sn) [22][23][24], and Si-Al-Zn [25] solvents have been investigated for the removal of impurities; however, a more effective enhanced solid/liquid segregation tendency of impurities has not been achieved. The separation of primary Si (refined Si) from a Si-based solvent is another essential issue for the production of SOG-Si.…”

Section: Introductionmentioning

confidence: 99%

Effect of solidification conditions on the silicon growth and refining using Si–Sn melt

Lei

Yoshikawa

et al. 2015

Journal of Crystal Growth

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Effect of solidification conditions on the silicon growth and refining using si-Sn melt, Journal of Crystal Growth, http://dx.doi.org/10.1016/j. jcrysgro. 2015.08.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Institute of Industrial Science, The University of Tokyo, Tokyo, Japan. AbstractThe solidification refining of Si using a Si-Sn solvent was investigated under various cooling conditions: (1) slow cooling, (2) slow cooling with electromagnetic stirring, and (3) directional solidification with the aim of developing a novel low-cost route for solar-grade Si production. The separation efficiency of refined Si achieved by combining slow cooling and electromagnetic stirring was much higher than that achieved using directional solidification; in addition, the purification efficiency of the refined Si in both methods was similar. The separation mechanism of refined Si from a Si-Sn melt is also discussed. Purification testing of the refined Si revealed that more than 96% of the metallic impurities, approximately 60% B, and over 70% P were removed.

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“…Solvent refining is a purification process that relies on preferential segregation of impurities to a liquid, which high purity solid silicon crystals are grown from. Some elements, such as aluminum [5,9], tin [10], iron [11], copper [12], sodium [13], gallium [14] etc., were selected as the solvent, and the experimental results all indicated that impurities, especially for B and P, could be reduced to some extent. The metal-solvent was selected taking into account the required properties of low melting point, good dissolving ability of silicon, chemical inertness, and low segregation coefficients of the impurities, thus providing a high efficiency of crystallization purification.…”

Section: Introductionmentioning

confidence: 99%

Removal of Impurities from Metallurgical Grade Silicon During Ga-Si Solvent Refining

Ban

et al. 2015

Silicon

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Purification of metallurgical grade silicon (MGSi), using gallium as the impurity getter has been investigated. The technique involves growing Si dendrites from an alloy of MG-Si with Ga, followed by their separation by acid leaching. The morphologies of impurity phases in the MG-Si and the Ga-Si alloy were investigated during the solvent refining process. Effective segregation ratios of B and P in the Ga-Si system were calculated. Most metallic impurities formed silicides, such as Si-Fe-Ga-Mn or Si-Fe-Ga impurity phases, which segregated to the grain boundaries of Si or into the Ga phase during the Ga-Si solvent refining process. After purification, the refined Si is plate-like with <111> crystallographic orientation, and the removal fraction of B and P was 83.28 % and 14.84 % respectively when the Si proportion was 25 % in the Ga-Si alloy. The segregation ratios of B and P were determined to be 0.15 and 0.83 when the solid fraction of Si was 0.25. The effective removal of B and P by a solidification refining process with a Ga-Si melt is clarified.

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Purification of metallurgical silicon using iron as impurity getter, part II: Extent of silicon purification

Cited by 69 publications

References 12 publications

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon

Effect of solidification conditions on the silicon growth and refining using Si–Sn melt

Removal of Impurities from Metallurgical Grade Silicon During Ga-Si Solvent Refining

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Purification of metallurgical silicon using iron as impurity getter, part II: Extent of silicon purification

Cited by 69 publications

References 12 publications

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO2 in Molten CaCl2 for the Production of Solar‐Grade Silicon

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO2 in Molten CaCl2 for the Production of Solar‐Grade Silicon

Effect of solidification conditions on the silicon growth and refining using Si–Sn melt

Removal of Impurities from Metallurgical Grade Silicon During Ga-Si Solvent Refining

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Product

Resources

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Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon

Improving Purity and Process Volume During Direct Electrolytic Reduction of Solid SiO₂ in Molten CaCl₂ for the Production of Solar‐Grade Silicon