Impurity phases and their removal in Si purification with Al–Si alloy using transition metals as additives

Lei, Yun; Ma, Wenhui; Wu, Jijun; Wei, Kuixian; Li, Shaoyuan; Morita, Kazuki

doi:10.1016/j.jallcom.2017.10.292

Cited by 31 publications

(5 citation statements)

References 42 publications

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“…The added Zr could be eliminated together with other impurities (removal fraction of 99.998%) because of its extremely small segregation coefficient (1.6 × 10 –8 at 1687 K). Therefore, the added Zr did not contaminate the purified Si in the process of Si purification . Additionally, the formation of ZrB 2 in the Al–Si alloy can improve the properties of the Al–Si alloy significantly, and the removal of Zr from the Al melt can be enhanced with B treatment .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the added Zr did not contaminate the purified Si in the process of Si purification. 24 Additionally, the formation of ZrB 2 in the Al−Si alloy can improve the properties of the Al−Si alloy significantly, 25 and the removal of Zr from the Al melt can be enhanced with B treatment. 26 However, the mechanism of ZrB 2 formation in the Al−Si alloy has not been discovered, which is significantly important for controlling the B removal using Zr theoretically and practically.…”

Section: ■ Introductionmentioning

confidence: 99%

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Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Lei

Qiu

Chen

et al. 2019

ACS Sustainable Chem. Eng.

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The formation of ZrB2 particles in Al–Si alloys not only improves the properties of the Al–Si alloy but also helps remove B from Si for the preparation of solar-grade Si. A thermodynamic study was performed to identify the mechanism of ZrB2 formation in Al–Si alloys. The precipitated B-bearing particles, i.e., ZrB x , were determined to be ZrB2 via electron probe microanalysis. The composition of the Al–Si alloy, which could form stable ZrB2 particles, was determined by measuring and calculating the equilibrium concentrations of Zr and B and the solubility products of ZrB2 in a Si-saturated Al–Si alloy at different temperatures. Thereafter, the segregation coefficients of B between solid Si crystals and the Si-saturated Al–Si melt with and without Zr addition were estimated thermodynamically. The mechanism whereby the B removal from Si was enhanced with Zr addition was as follows: the Zr not only reduced the concentration of B in the molten Al–Si but also significantly reduced the segregation coefficient of B between the solid Si and Si-saturated Al–Si melt.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Lei

Qiu

Chen

et al. 2019

ACS Sustainable Chem. Eng.

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“…The Si crystals first solidified at the beginning of the solidification process of Si alloys, and Nd and other elements formed low-melting phases (liquid phases) that finally solidified and agglomerated along the Si grain boundary. The segregation coefficients of Fe, Ti, V, Mn, Al, and Ca between solid to liquid Si were previously reported to be 6.4 × 10 –6 , 2.0 × 10 –6 , 4.0 × 10 –6 , 1.3 × 10 –5 , 8.0 × 10 –2 , and 8.0 × 10 –3 , respectively. , Although the segregation coefficient of Nd has not yet been reported, Nd likely agglomerated along the Si grain boundary, given that no Nd was detected in the Si grains.…”

Section: Results and Discussionmentioning

confidence: 93%

Novel Approach for the Simultaneous Recovery of Nd from Nd₂O₃-Containing Slag and the Preparation of High-Purity Si

Lei

et al. 2021

ACS Sustainable Chem. Eng.

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The extraction of rare earth elements (REEs) from rare earth oxide slag is a major challenge of recycling REEs from REE-containing wastes using pyrometallurgical approaches, especially the recycling of Nd from spent NdFeB permanent magnets. In this study, a novel and effective approach is proposed for extracting Nd from Nd 2 O 3 -containing slag. First, low-purity Si (99.2%) was used as a reductant to extract Nd from Nd 2 O 3containing slag to prepare a bulk Si−Nd alloy. The bulk Si−Nd alloy represents one of the final products and achieves the purpose of Nd recycling because of its wide applications; alternatively, the bulk Si−Nd alloy can be further separated into Si powder and Ndcontaining HCl solution by HCl acid leaching. Thereafter, three methods can be used to recover Nd from the Nd-containing HCl solution: (1) NH 3 •H 2 O can be used to precipitate Nd 3+ as NdOCl hydrate sediment, which is roasted to obtain high-purity NdOCl (99.0%); (2) HF can be used to precipitate Nd 3+ as NdF 3 (97.0%); or (3) NdCl 3 •6H 2 O (98.1%) can be obtained after completely distilling the Nd-containing HCl solution. This new technology not only permits the recovery of Nd from the Nd 2 O 3 -containing slag but also increases the purity of Si from 99.2 to 99.997%.

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“…Metallurgical-grade silicon (MG-Si) is a basic raw material for producing semiconductor materials, solar cells, organosilicon, and high-purity silicon alloys [1][2][3]. It is widely used in aerospace, defense, new energy, electronic and electrical, and other important basic industries [4][5][6][7]..The MG-Si re ned slag (MGSRS) is the solid waste produced during the MG-Si re ning production process, which contains more than 15% silicon [8]. In 2022, the global yield of MG-Si is approximately 4.5 million tons, nearly 700,000 tons of MGSRS were produced.…”

Section: Introductionmentioning

confidence: 99%

Effect of Grinding Liberation on Recovery of Silicon from MG-Si Waste Slag by Flotation

Tan,

Han,

Wei

et al. 2024

Silicon

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Metallurgical-grade silicon-re ned waste slag (MGSRS) was produced during the MG-Si re ning production process, which occupies huge amounts of land resources, caused the loss of nearly 110,000 tons of MG-Si every year. Though, it is of great signi cance to recover the elemental silicon in MGSRS.However, because silicon is tightly wrapped by slag and di cult to separate, resulting in the di culty of silicon recovery. In this study, silicon recovery powders were obtained through the process of grinding liberation and otation separation. The effect of grinding time on the liberation of MGSRS and the otation recovery of silicon was studied. The liberation mechanism of MGSRS was further discussed. The results showed that the liberation degree of silicon particles was 79.45% (grinding for 15 min), which was 7.94% higher than that of silicon particles after 5 min grinding time, and 77.15% of the silicon particles were fully liberated. The otation recovery of silicon can increase from 10.5-78.7% with the appropriate collector. Mechanism study shows that during the grinding process, silicon was separated along the (111) surface, and Ca 2 Al 2 SiO 7 had the largest amount of liberation along the (211) plane. More unsaturated sites of aluminum and calcium ions were observed on the silicate surface, which were favorable for adsorption with the reagent and bene cial to the silicon recovery. These results indicated that the silicon and slag of MGSRS can be su ciently separated through grinding and otation, and the purity of recovered silicon is about 70%. The silicon resources in MGSRS were recovered economically and could be used as the raw materials for the preparation of silicon alloy and high purity silicon.

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Impurity phases and their removal in Si purification with Al–Si alloy using transition metals as additives

Cited by 31 publications

References 42 publications

Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Novel Approach for the Simultaneous Recovery of Nd from Nd₂O₃-Containing Slag and the Preparation of High-Purity Si

Effect of Grinding Liberation on Recovery of Silicon from MG-Si Waste Slag by Flotation

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Impurity phases and their removal in Si purification with Al–Si alloy using transition metals as additives

Cited by 31 publications

References 42 publications

Mechanism of ZrB2 Formation in Al–Si Alloy and Application in Si Purification

Mechanism of ZrB2 Formation in Al–Si Alloy and Application in Si Purification

Novel Approach for the Simultaneous Recovery of Nd from Nd2O3-Containing Slag and the Preparation of High-Purity Si

Effect of Grinding Liberation on Recovery of Silicon from MG-Si Waste Slag by Flotation

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Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Mechanism of ZrB₂ Formation in Al–Si Alloy and Application in Si Purification

Novel Approach for the Simultaneous Recovery of Nd from Nd₂O₃-Containing Slag and the Preparation of High-Purity Si