Purification of metallurgical-grade silicon powder via chemical attack by hydrofluoric and nitric acids followed by thermal treatment

2013 ◽  
Vol 16 (6) ◽  
pp. 1742-1746 ◽  
Author(s):  
Marouan Khalifa ◽  
Malek Atyaoui ◽  
Messaoud Hajji ◽  
Rachid Ouertani ◽  
Hatem Ezzaouia
Keyword(s):  
Thermal Treatment ◽  
Silicon Powder ◽  
Metallurgical Grade Silicon ◽  
Chemical Attack ◽  
Grade Silicon

Electrolysis Process for Preparation of Solar Grade Silicon

2011 ◽  
Vol 391-392 ◽  
pp. 697-702 ◽  
Author(s):  
Xiang Yu Zou ◽  
Hong Wei Xie ◽  
Yu Chun Zhai ◽  
Xiao Chuan Lang ◽  
Jun Zhang
Keyword(s):  
Electrochemical Method ◽  
Silicon Powder ◽  
Argon Atmosphere ◽  
Impurity Level ◽  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Pure Silicon ◽  
Cell Components ◽  
Nickel Crucible ◽  
Grade Silicon

Studied on electrorefining metallurgical grade silicon to prepare solar grade silicon(SOG-Si) with electrochemical method in molten KCl and NaF mixture salt. Molten KCl and NaF mixture salt as electrolyte, the metallurgical grade silicon as anode and little metal nickel crucible for collecting silicon powder as cathode, electrorefining experiments were performed at 800 and 2.0V for 14h under dry argon atmosphere. The results showed that the metallurgical grade silicon could be dissolved and deposited on the cathode through molten potassium chloride (KCl) and sodium fluoride (NaF) mixture salt electrolyte. The nickel crucible was full of deposit, which was pure silicon by XRD and EDS. Purity of refined silicon was close to 99.99%, most of impurities like B and P were reduced significantly. Impurity level of silicon was reduced to the desired range for SOG-Si by advancement of the materials for the cell components.

Transition-Metal Impurities Removal from Metallurgical Grade Silicon by Electron Beam Injection

2011 ◽  
Vol 675-677 ◽  
pp. 105-108
Author(s):  
Rui Xun Zou ◽  
Da Chuan Jiang ◽  
Wei Dong ◽  
Zheng Gu ◽  
Yi Tan
Keyword(s):  
Electron Beam ◽  
Transition Metal ◽  
Removal Rate ◽  
Silicon Powder ◽  
Sio2 Film ◽  
Metallurgical Grade Silicon ◽  
Beam Injection ◽  
Metal Impurities ◽  
Transition Metal Impurities ◽  
Grade Silicon

The electron beam injection (EBI) process involves offering electrons around silicon powder, whose surface was oxidized, and subsequently the powder is washed by HF acid so as to remove the SiO2 film. The new electron beam injection process, in which micro electric filed formed between Si and SiO2 film will accelerate impurities diffusion from Si to SiO2 film, was developed and applied to eliminate the transition-metal impurities of MG-Si. It is proved to be effective to remove transition-metal impurities from metallurgical grade silicon (MG-Si). By applying the electron beam injection method, the removal rate of 10% to 59% was achieved during the refining process. The efficiency of impurity removal originates from two aspects: the impurity concentration gradient on both sides of Si/SiO2 interface; the micro electric field formed from Si to SiO2 film. A further increase in the removal rate can be realized by controlling the processing parameters.

Multi-scale chemical characterization of a ground metallurgical-grade silicon powder

2015 ◽  
Vol 270 ◽  
pp. 98-103 ◽  
Author(s):  
Eloi Kewes ◽  
Franck Dahlem ◽  
Sandrine Bec ◽  
Nicolas Estime ◽  
Khalid Hoummada ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Silicon Powder ◽  
Metallurgical Grade Silicon ◽  
Multi Scale ◽  
Grade Silicon

Metal Impurities Removal from Metallurgical Grade Silicon by Hydrochloric Acid Leaching

2013 ◽  
Vol 813 ◽  
pp. 7-10 ◽  
Author(s):  
Xiao Ming Li ◽  
Yan Mei Dang ◽  
Wen Feng Li ◽  
Jun Xue Zhao ◽  
Ya Ru Cui
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Mass Fraction ◽  
Acid Leaching ◽  
Silicon Powder ◽  
Metallurgical Grade Silicon ◽  
Mechanical Stirring ◽  
Grade Silicon ◽  
Impurities Removal ◽  
Hydrometallurgical Method

As a pre-treatment process for producing solar-grade silicon, hydrometallurgical method could remove the most of metallic impurities of metallurgical-grade silicon, which is a hopeful technology to provide solar energy material independence of the Siemens skill. Factors such as the hydrochloric mass fraction, temperature, reaction time, and particle size of silicon powders were investigated in the impurities removal experiments under the condition of mechanical stirring. The leached samples were analyzed by ICP and SEM. The optimum parameters, hydrochloric mass fraction 5%, temperature 80°C, reaction time 9h, particle size 75μm, were determined by single factor experiments and orthogonal experiments. The 86.1% of Fe, 68.1% of Al, 85.9% of Ca and 25.9% of B impurity was removed from metallurgical-grade silicon powder.

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.

The Method for Enhancing Nitrogen Doping in 6H-SiC Single Crystals Grown by Sublimation Process: The Effect of Si Addition in SiC Powder Source

2006 ◽  
Vol 527-529 ◽  
pp. 55-58 ◽  
Author(s):  
Kwan Mo Kim ◽  
Soo Hyung Seo ◽  
Jae Woo Kim ◽  
Joon Suk Song ◽  
Myung Hwan Oh ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Single Crystals ◽  
Nitrogen Doping ◽  
Doping Concentration ◽  
Silicon Powder ◽  
Mixed Powder ◽  
Nitrogen Doped ◽  
Sublimation Method ◽  
Si Content ◽  
Si Addition

The variation of nitrogen doping concentration was systematically investigated with respect to the amount of silicon powder added to the SiC powder for growing n-type 6H-SiC single crystal by the sublimation method. To change intentionally the Si content in the SiC powder, 0wt% to 2wt% of a silicon powder was added to first-thermal treated SiC powder and the mixed powder was treated again at 1800oC for 3 hours to eliminate excess free-metallic silicon. Nitrogen doped 6H-SiC single crystals were grown by using 2nd-thermal treatment SiC powder at fixed N2/(Ar + N2) (3%). The nitrogen doping concentration of 6H-SiC crystals increased with increasing Si content in the SiC powder. In this work, we could identify that the additional silicon powder in SiC powder plays a role in the enhancement of nitrogen doping in 6H-SiC crystals grown by the sublimation method.

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