Mechanism of Carbon Removal from Crude Metallurgical Grade Silicon during Oxidation Refining

Silicon ◽  
2021 ◽  
Author(s):  
Jianhua Wen ◽  
Xiaocong Deng ◽  
Kuixian Wei ◽  
Wenhui Ma
Keyword(s):  
Metallurgical Grade Silicon ◽  
Carbon Removal ◽  
Grade Silicon ◽  
Oxidation Refining

scholarly journals Nucleation of SiO$$_{2}$$-CaO-Al$$_{2}$$O$$_{3}$$ Slag in Oxidative Ladle Refining of Metallurgical Grade Silicon

2021 ◽  
Author(s):  
Erlend L. Bjørnstad ◽  
Gabriella Tranell
Keyword(s):  
Liquid Alloy ◽  
Molten Slag ◽  
Liquid Structure ◽  
Theoretical Description ◽  
Metallurgical Grade Silicon ◽  
Ladle Refining ◽  
Active Nature ◽  
Process Behavior ◽  
Surface Active ◽  
Grade Silicon

AbstractOxidative ladle refining (OLR) is the most used refining method in industrial production of metallurgical grade silicon. OLR is performed by purging the liquid alloy with oxygen-enhanced air at 1823 K to 1873 K, reacting with silicon and the primary slag forming impurities to a SiO$$_{2}$$ 2 -CaO-Al$$_{2}$$ 2 O$$_{3}$$ 3 slag. To further increase our capability to control this process, it is paramount to understand how the slag nucleates and forms, and represent it such that it is useful for predicting and controlling the process behavior. This work aims to formulate a comprehensive theoretical description of slag nucleation and formation at nano/microscale using classical macroscale thermodynamics, bridging these spatial regimes. To achieve this, the work argues that silica’s liquid structure allows its nuclei to exhibit “well defined” surfaces. Furthermore, silica is predicted to be highly surface active, so if its concentration is high while the slag nucleus is small, the SiO$$_{2}$$ 2 -CaO-Al$$_{2}$$ 2 O$$_{3}$$ 3 slag should retain silica’s surface properties. An experiment confirmed the surface active nature of silica in the SiO$$_{2}$$ 2 -CaO-Al$$_{2}$$ 2 O$$_{3}$$ 3 system. It was also shown that increasing the slag’s calcia concentration has a greater effect on the interfacial tension between the molten slag and liquid alloy than alumina, confirming industrial observations of the coupling between refining rate and relative alloy/slag composition.

Removal of aluminum from metallurgical grade silicon using electron beam melting

Vacuum ◽  
2011 ◽  
Vol 86 (4) ◽  
pp. 471-475 ◽  
Author(s):  
Xu Peng ◽  
Wei Dong ◽  
Yi Tan ◽  
Dachuan Jiang
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon

Study of the Removal of Boron from Metallurgical Grade Silicon by Oxidation Slagging Method

2010 ◽  
Vol 156-157 ◽  
pp. 882-885 ◽  
Author(s):  
Yu Yan Hu ◽  
Dong Liang Lu ◽  
Tao Lin ◽  
Yu Liu ◽  
Bo Wang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Orthogonal Experiment ◽  
Slag System ◽  
Refining Process ◽  
Impact Factors ◽  
Metallurgical Grade Silicon ◽  
Optimum Parameters ◽  
Grade Silicon ◽  
Refining Time ◽  
The Impact

Refining of solar grade silicon by metallurgical method is the research hotspot of polycrystalline field. Slagging method is benefit to the removal of the impurities especially to boron exsisted in the raw silicon. In this study, the influence of the density, the viscosity and liquidus temperature of the slag components on the refining process were discussed, and then the slag system SiO2-Na2CO3 was choosed as the slagging agents. And then the impact factors on the removal efficiency of boron such as the composition of SiO2 and Na2CO3, the ratio of slag to silicon and the refining time were investigated by the orthogonal experiment. The results showed that the optimum parameters of the oxidation refining for removing boron were as follows: the main composition of the oxidant is “SiO2 : Na2CO3 = 60% : 40%”; the slag/silicon ratio is 0.5; time for refining is 60min at 1550 . The results indicated that the removal efficiency of boron was 88.28%, and the content of boron in MG-Si can be reduced to 7ppmw under the best refining process¬.

Comparison between slag refining processes for B removal with metallurgical grade silicon and Si–Sn alloy

2018 ◽  
Vol 115 (3) ◽  
pp. 312 ◽  
Author(s):  
Rowaid Al-khazraji ◽  
Yaqiong Li ◽  
Lifeng Zhang
Keyword(s):  
Removal Efficiency ◽  
Acid Leaching ◽  
Experimental Results ◽  
Mass Ratio ◽  
Metallurgical Grade Silicon ◽  
Clear Effect ◽  
Slag Refining ◽  
Before And After ◽  
Grade Silicon ◽  
Refining Processes

Boron (B) removal by slag refining using CaO–SiO2–CaCl2 was investigated in metallurgical-grade silicon (MG-Si) and 75 wt% Si–Sn alloy. Experiments were conducted at 1500 °C for 15 min. The microstructure was characterized before and after refining. The effects of acid leaching, basicity, and slag/Si mass ratio on B removal were investigated. Experimental results showed that acid leaching had no effect on B removal from MG-Si but had a clear effect on the refined Si–Sn alloy after slag refining. The final B concentration was highly affected by the CaO/SiO2 mass ratio with minimum value, where the content of B was reduced from 18.36 ppmw to 5.5 ppmw at the CaO/SiO2 = 1.2 for MG-Si slag refining and from 18.36 ppmw to 3.7 ppmw at CaO/SiO2 = 1.5 for 75 wt% Si–Sn alloy. Increasing the slag mass ratio by 2:1 mass ratio also increased B removal efficiency by approximately 15–20% more than an increase by 1:1.

Purification of Metallurgical-Grade Silicon by Acid Leaching

Silicon ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 1979-1987 ◽  
Author(s):  
Farzad Ebrahimfar ◽  
Mahdi Ahmadian
Keyword(s):  
Acid Leaching ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon

Boron removal in purifying metallurgical grade silicon by CaO–SiO2 slag refining

2014 ◽  
Vol 24 (4) ◽  
pp. 1231-1236 ◽  
Author(s):  
Ji-jun WU ◽  
Yan-long LI ◽  
Wen-hui MA ◽  
Kui-xian WEI ◽  
Bin YANG ◽  
...  
Keyword(s):  
Boron Removal ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Grade Silicon

Boron removal from metallurgical-grade silicon using lithium containing slag

2012 ◽  
Vol 358 (18-19) ◽  
pp. 2708-2712 ◽  
Author(s):  
Zhao Ding ◽  
Wenhui Ma ◽  
Kuixian Wei ◽  
Jijun Wu ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Boron Removal ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon

Production of solar-grade silicon by refining of liquid metallurgical-grade silicon

1999 ◽  
Author(s):  
Chandra P. Khattak ◽  
Frederick Schmid ◽  
David B. Joyce ◽  
Eugene A. Smelik ◽  
Mark A. Wilkinson
Keyword(s):  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon
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