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.

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.

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.

scholarly journals Removing boron from metallurgical grade silicon by a high basic slag refining technique

2014 ◽  
Vol 50 (1) ◽  
pp. 83-86 ◽  
Author(s):  
J.J. Wu ◽  
M. Xu ◽  
K.B. Liu ◽  
W.H. Ma ◽  
B. Yang ◽  
...  
Keyword(s):  
Distribution Coefficient ◽  
Boron Concentration ◽  
Basic Slag ◽  
Mass Ratio ◽  
Purification Method ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Thermodynamic Relationship ◽  
Grade Silicon ◽  
Maximal Distribution

A new purification method of removing boron from metallurgical grade silicon (MG-Si) using a high baisicity slag was developed in this paper. The typical impurities Al, Ca, Ti, B, P etc in MG-Si can be removed by the binary calcium sillicate slag and it is especially efficient for removing impurity Boron. It was found that the maximal distribution coefficient of boron between calcium sillicate slag and silicon reaches to 1.57 when the mass ratio of CaO/SiO2 was 1.5 and the composition was 60%CaO-40%SiO2. It showed that the oxidizability of calcium sillicate slag was affected and restricted by the basicity and the mass ratio of acid oxide SiO slag according to the thermodynamic relationship. The boron concentration in MG-Si can be reduced from 18x10-6 to 4.5x10-6 and 1.4x10-6, respectively, when using the ternary slags 40.5%CaO-49.5%SiO2-10%Li2O and 32CaO-38%SiO2-30%Li2O.

Enhancement of boron removal from metallurgical-grade silicon by titanium addition during slag refining

2021 ◽  
Vol 118 (6) ◽  
pp. 612
Author(s):  
Yaqiong Li ◽  
Lifeng Zhang ◽  
Ligang Liu
Keyword(s):  
Acid Leaching ◽  
Boron Removal ◽  
Titanium Addition ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Grade Silicon ◽  
Ti Addition

The effects of titanium addition (0 wt.%, 0.2 wt.%, and 0.5 wt.%) on the boron removal from metallurgical-grade silicon during slag refining have been studied. According to the findings, the addition of Ti improved the removal of 92.5 wt.% B with 0.5 wt.% Ti addition compared to 79.4 wt.% B removal without Ti addition. Furthermore, acid leaching reduced excess Ti to 27 ppmw.

Removal of boron from metallurgical grade silicon by CaO-SiO2 based slags

2019 ◽  
Vol 116 (4) ◽  
pp. 413
Author(s):  
Yong Hou ◽  
Yue-dong Wu ◽  
Guo-Hua Zhang ◽  
Kuo-Chih Chou
Keyword(s):  
Rare Earth ◽  
Partition Coefficient ◽  
Rare Earth Oxides ◽  
Molar Ratio ◽  
Mass Ratio ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Maximum Value ◽  
Grade Silicon ◽  
The Rare Earth

Slag refining is one of the most effective methods to remove boron from metallurgical grade silicon (MG-Si). In this paper, the removal of boron from metallurgical grade silicon was proposed by adding CaF2, BaO or rare earth oxides (La2O3 and CeO2) to CaO-SiO2 based slags. The effects of the BaO content, the CaF2 content, the rare earth oxides content, the molar ratio of CaO to SiO2 and the mass ratio of slag to silicon on the partition coefficient of boron (LB) between slag and silicon are investigated. The results show that LB has a maximum value of 5.17 in 45% CaO-45% SiO2-10% BaO slags at 1550 °C after reacting for 6 h with a slag to silicon mass ratio of 2. Besides, it is found that the addition of La2O3 or CeO2 shows better de-boronization ability compared with the addition of BaO.

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.

scholarly journals Boron removal from metallurgical grade silicon using a FeCl2 molten salt refining technique

2013 ◽  
Vol 49 (3) ◽  
pp. 257-261 ◽  
Author(s):  
B.J. Jia ◽  
J.J. Wu ◽  
W.H. Ma ◽  
B. Yang ◽  
D.C. Liu ◽  
...  
Keyword(s):  
Molten Salt ◽  
Boron Concentration ◽  
Metallurgical Process ◽  
Mass Ratio ◽  
Solar Grade Silicon ◽  
Boron Removal ◽  
Metallurgical Grade Silicon ◽  
Slag Refining ◽  
Grade Silicon ◽  
Refining Time

The slag refining for boron removal from metallurgical grade silicon is a promising metallurgical process for producing solar grade silicon. In this paper, FeCl2 molten salt has been used as a new refining agent to remove boron from MG-Si. The effects of refining time and mass ratio of MG-Si to FeCl2 molten salt on boron removal have been investigated in detail. The results showed that boron can be efficiently removed in form of BCl3 and boron concentration in MG-Si was successfully reduced from 22?10-6 to 4?10-6 at 1823K for 2 h with the mass ratio of FeCl2 molten salt to MG-Si for 1.0. The rate equation of boron removal using FeCl2 molten salt was proposed and established in kinetic, which showed a large difference in removal limitation of boron compared with thermodynamics.

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¬.

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
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