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.

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

Removal of Boron from Metallurgical Grade Silicon by Chloride Molten Salt

2013 ◽  
Vol 634-638 ◽  
pp. 3084-3087
Author(s):  
Bin Jie Jia ◽  
Ji Jun Wu ◽  
Wen Hui Ma ◽  
Yan Long Li
Keyword(s):  
Molten Salt ◽  
Thermodynamic Analysis ◽  
Boron Content ◽  
Induction Furnace ◽  
Solar Grade Silicon ◽  
Medium Frequency ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon ◽  
Refining Time ◽  
Boron Chloride

Removal of boron is one of the greatest barriers in the process of upgrading metallurgical grade silicon (MG-Si) to solar grade silicon (SoG-Si). In this work, a chloride molten salt was used as a new refining reagent for removal of boron from MG-Si. The theoretical supporting for chloride molten salt refining was studied by the thermodynamic analysis at first, which testified that boron could be volatilized and removed from MG-Si melt by generating the gaseous boron chloride species. Then the experiments for the removal of boron were carried out using the chloride molten salt with the different conditions of refining time and the ratio of chloride molten salt to MG-Si. The results showed that the boron content in refined silicon was successfully reduced from 22.0×10-6 to 3.0×10-6 in a medium frequency induction furnace at 1695 K for 2h.

Ca-Si Alloy Addition Followed by Acid Leaching as a Route to Solar-Grade Silicon

2014 ◽  
Vol 881-883 ◽  
pp. 1562-1567
Author(s):  
Peng Zou ◽  
Kui Xian Wei ◽  
Wen Hui Ma ◽  
Ke Qiang Xie ◽  
Ji Jun Wu ◽  
...  
Keyword(s):  
Phosphorus Content ◽  
Low Cost ◽  
Acid Leaching ◽  
Impurity Phase ◽  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Before And After ◽  
Alloy Addition ◽  
Grade Silicon ◽  
Leaching Condition

In present, refining of metallurgical grade silicon is one of the promising routes to low-cost solar grade silicon for solar cells. Alloying with Ca has shown a great potential as efficient refining method of MG-Si in combination with acid leaching. Compared with Ca metal, Ca-Si alloy is cheaper and more secure. Great removal of impurity depends on microstructure of MG-Si after alloyed with Ca-Si alloy. In the work, the change of impurity phase which was performed by the change of the microstructure of MG-Si before and after alloyed with Ca-Si alloy has been analyzed. It was determined that CaSi2phase contained significant phosphorus content after alloying with Ca-Si alloy, It also investigated the optimal acid leaching condition after leaching, which confirmed that metallurgical grade silicon with Ca-Si alloy addition followed by acid leaching could be a potential route to remove phosphorus from MG-Si.

Purification of Refined Metallurgical-grade Silicon up to Solar Grade Silicon by Extraction

2009 ◽  
Vol 1170 ◽  
Author(s):  
Sergey M Karabanov ◽  
Dmitriy V Suvorov ◽  
Boris N Sazhin
Keyword(s):  
Particle Size ◽  
Impurity Concentration ◽  
Solid Phase ◽  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Time Dynamics ◽  
Axial Profile ◽  
Grade Silicon ◽  
Silicon Purification ◽  
Method Of Extraction

AbstractThe paper studies the theoretical analysis of silicon purification process using the method of extraction from solid phase in fine-dyspersated condition. Axial profile impurity concentration in silicon particles, time dynamics of average impurity concentration at various purification conditions (temperature, particle size, impurity concentration in extractant) are obtained by numerical simulation. The requirements to a particle size and temperature condition when practically important purification efficiency is reached, are determined. The design of an industrial-scale plant is shown schematically.

Low-cost solar grade silicon powder through iterative gettering of thermally treated porous silicon

2016 ◽  
Vol 83 ◽  
pp. 324-328 ◽  
Author(s):  
Marouan Khalifa ◽  
Malek Atyaoui ◽  
Rachid Ouertani ◽  
Messaoud Hajji ◽  
Hatem Ezzaouia
Keyword(s):  
Porous Silicon ◽  
Low Cost ◽  
Silicon Powder ◽  
Solar Grade Silicon ◽  
Grade Silicon ◽  
Thermally Treated

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.

Effect of Sodium-Based Slag Treatment on the Distribution of Impurities in Metallurgical Grade Silicon

2013 ◽  
Vol 690-693 ◽  
pp. 949-953
Author(s):  
Ming Fang ◽  
Cheng Hao Lu ◽  
Hui Xian Lai ◽  
Liu Qing Huang ◽  
Juan Chen ◽  
...  
Keyword(s):  
Slag Phase ◽  
Homogeneous Distribution ◽  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Metal Impurities ◽  
Precipitated Phase ◽  
Slag Treatment ◽  
Before And After ◽  
Grade Silicon ◽  
Metallic Impurities

The distribution of impurities in metallurgical grade silicon before and after slag treatment was investigated for the purpose of upgrading metallurgical grade to solar grade silicon. It was found that metal impurities co-deposited with silicon and formed different intermetallics in the precipitated phase, and these intermetallics such as Si-Fe, Si-Ni, Si-Ti-V and Si-Ca-Al-Fe were substituted by Si-Fe-Ti-V after treatment of Na2CO3-SiO2 slag. Non-metallic impurities B and P were nearly homogeneous distribution in metallurgical grade silicon before and after slag treatment. Moreover, a particular analysis of the microstructure of slag has been carried out, it was determined that metal impurities Al and Ca could easily migrate from silicon to slag phase in the refining process.

Purification of Silicon Using the Liquid Phase Migration Technique under Temperature Gradient

2013 ◽  
Vol 750 ◽  
pp. 240-243
Author(s):  
Kunitoshi Matsunaga ◽  
Takeshi Yoshikawa ◽  
Kazuki Morita
Keyword(s):  
Liquid Phase ◽  
Temperature Gradient ◽  
Grain Boundary ◽  
Eutectic Temperature ◽  
Solar Grade Silicon ◽  
Metallurgical Grade Silicon ◽  
Silicon Matrix ◽  
Grade Silicon ◽  
Impurity Elements ◽  
Migration Technique

A new conceptual technique for solar grade silicon (SOG-Si) purification was proposed in the present work. Most impurity elements in metallurgical grade silicon (MG-Si) exist in the grain boundary phases and their contents inside of silicon grains are extremely small, which is resulted from significant segregation during the solidification. Thus, the excellent purification was expected by selective ejection of grain boundary phases from silicon matrix. Such phases can be melted above the eutectic temperature of the system to form impurity-enriched liquid phase. In order to achieve the selective ejection of the liquid phase, its migration in the silicon matrix was investigated by conducting the heat treatment of silicon under the temperature gradient in this paper.

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