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.

Effects of Slag Refining and Vacuum Treatment on De-Phosphorus from MG-Si Using CaO-SiO2-CaCl2 Slag

2013 ◽  
Vol 815 ◽  
pp. 773-777
Author(s):  
Liu Qing Huang ◽  
Hui Xian Lai ◽  
Ming Fang ◽  
Cheng Hao Lu ◽  
Juan Chen ◽  
...  
Keyword(s):  
Detailed Analysis ◽  
Removal Efficiency ◽  
Vacuum Treatment ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Precipitated Phase ◽  
Obvious Change ◽  
Grade Silicon ◽  
P Distribution ◽  
P Removal

This paper presents a detailed analysis of the effect of slag refining and vacuum treatment on P removal from metallurgical-grade silicon using CaO-SiO2-CaCl2 slag. It demonstrates that both of CaO: SiO2 ratio and CaCl2 content have significant effects on the P removal. Increasing CaO: SiO2 ratio was found to decrease the P removal efficiency after slag refining and vacuum treatment, and the distribution of P shows a tendency to concentrate in the precipitated phase after slag refining. It is also determined that the highest removal efficiency of P was attained when CaCl2 content was 5wt%( CaO:SiO2=1:1), but no obvious change was observed on P distribution after slag refining of varying CaCl2 content.

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.

Distribution of Representative Impurities in Metallurgical-Grade Silicon Using CaO-SiO2-CaF2 and CaO-SiO2-CaCl2 Slags

2013 ◽  
Vol 813 ◽  
pp. 11-15
Author(s):  
Liu Qing Huang ◽  
Hui Xian Lai ◽  
Cheng Hao Lu ◽  
Ming Fang ◽  
Juan Chen ◽  
...  
Keyword(s):  
Detailed Analysis ◽  
Intermetallic Compounds ◽  
Removal Efficiency ◽  
Precipitate Phase ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Grade Silicon ◽  
Impurities Removal ◽  
Metallic Impurities

This paper presents a detailed analysis of impurities distribution in metallurgical-grade silicon after CaO-SiO2-CaF2 and CaO-SiO2-CaCl2 slags refining. It demonstrates that the impurities removal efficiency generally increase in metallurgical-grade silicon after CaO-SiO2-CaCl2 slag refining compared to that after CaO-SiO2-CaF2 slag refining. It is also determined that metallic impurities like Fe, Al and Ca tend to co-deposit with Si to form Si-Ca based intermetallic compounds in the precipitate phase after slag refining.

Impact of Impurities in Metallurgical Grade Silicon on Removal Efficiency of Vacuum Evaporation

2011 ◽  
Vol 287-290 ◽  
pp. 1521-1525
Author(s):  
Kui Xian Wei ◽  
Wen Hui Ma ◽  
Yang Zhou ◽  
Ke Qiang Xie ◽  
Bin Yang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Raw Materials ◽  
Vacuum Evaporation ◽  
Raw Material ◽  
Vacuum Furnace ◽  
Metallurgical Grade Silicon ◽  
Quality Product ◽  
Grade Silicon ◽  
And Performance ◽  
Volatile Impurities

Vacuum evaporation is usually utilized to remove volatile impurities in metallurgical grade silicon to prepare solar grade silicon by metallurgical routes. Especially phosphorus needs to be removed by vacuum evaporation. And the removal efficiency of impurities strongly influenced the quality and performance of products. In this paper, the removal efficiency of impurities is studied by using different raw material. The results indicated that the content of impurities in raw material had deep effect on the removal efficiency of vacuum evaporation. The high quality product can be obtained by vacuum evaporation only once from raw materials with the lower content of impurities whereas it is not for high content of impurities in raw material. This is due to the vapor-liquid equilibrium in the vacuum furnace. The impurities can be removed effectively by vacuum evaporation many times.

Removal of Iron from Metallurgical Grade Silicon with Pressure Leaching

2011 ◽  
Vol 675-677 ◽  
pp. 873-876 ◽  
Author(s):  
Ke Qiang Xie ◽  
Zhan Liang Yu ◽  
Wen Hui Ma ◽  
Yang Zhou ◽  
Yong Nian Dai
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Removal Efficiency ◽  
Acid Concentration ◽  
Operating Conditions ◽  
Raw Material ◽  
Optimum Operating ◽  
Pressure Leaching ◽  
Metallurgical Grade Silicon ◽  
Grade Silicon

In this paper, removal of iron from metallurgical grade silicon with pressure leaching is carried out. We investigated the factors such as the concentration of hydrochloric, particle size of raw material ground, temperature, pressure and reaction time, which influenced on the removal of iron. The results show that the optimum operating conditions for pressure leaching in hydrochloride are: acid concentration 4 mol/L, diameter for raw material less than 50 μm, leaching temperature 160 0C，leaching pressure 2.0 MPa, leaching time 2.0 h. The content of iron residual in MG-Si powder was reduced to about 200 ppmw. The removal efficiency of iron is up to 90.90 %.

Diffusion and mass transfer of boron in molten silicon during slag refining process of metallurgical grade silicon

2015 ◽  
Vol 404 ◽  
pp. 70-74 ◽  
Author(s):  
Jijun Wu ◽  
Fanmao Wang ◽  
Zhengjie Chen ◽  
Wenhui Ma ◽  
Yanlong Li ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Refining Process ◽  
Molten Silicon ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Grade Silicon

The Influence of Cooling Water Flow to Purify the Metallurgical Grade Silicon by Directional Solidification

2013 ◽  
Vol 712-715 ◽  
pp. 784-787
Author(s):  
Tao Lin ◽  
Da Jun Zhang ◽  
Chun Yan Duan ◽  
Dong Liang Lu
Keyword(s):  
Directional Solidification ◽  
Water Flow ◽  
Removal Efficiency ◽  
Cooling Water ◽  
Experimental Results ◽  
Metallurgical Grade Silicon ◽  
Density Of Dislocations ◽  
Silicon Ingot ◽  
Metal Impurities ◽  
Grade Silicon

Directional solidification is one of the most important processes to purify the impurities in the metallurgical grade silicon. A lot of factors could influence the result of directional solidification. In this paper, we researched cooling water flow which could influence the result of directional solidification. We have studied three data of cooling water flow which influenced the results of the removal efficiency of the impurities. Experimental results showed that cooling water flow can influence the density of dislocations and twins in the ingot. The metal impurities of Al, Fe and Ca were concentrated in the middle of the silicon ingot mostly. It was inferred that the bigger cooling water flow was better to the efficiency of the purification in the experiment.

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