Papers by Keyword: Boron Removal

Abstract: This work investigates the removal of B in Si by the addition of Zr in the electromagnetic solidification refinement of silicon-aluminum melts. As Zr has a strong affinity for B and can form the thermodynamically stable compound of ZrB₂, the B content of lower-grade Si is expected to be effectively removed by adding a small amount of Zr to the Si-55 at% Al melt. The results show that Zr is strongly responsible for the decrease in B content of refined Si. The removal fraction of B significantly increased from 60.2% to 97.3% by adding a small amount of Zr (0 to 3500 ppmw). In addition, the removal fraction of Zr from Si was found to be as high as 98.6%; however, its residual content in the refined Si was significantly larger than its solid solubility in Si, possibly due to the non-equilibrium solidification occurring during the refining process.

Abstract: The kinetic behavior of a new adsorbent prepared by radiation induced grafting of vinyl benzyl chloride (VBC) onto nylon-6 fibers followed by functionalization with N-methyl-D-glucamine was investigated using pseudo second-order kinetic model. The linear method and non-linear regression methods were compared to determine the best fitting for the kinetic model describing the adsorption of boron by the new adsorbent. Four pseudo second-order kinetic linear equations were presented. A type-1 pseudo second-order linear method was found to fit best the experimental data. Non-linear regression method was found to be more appropriate to describe the boron adsorption by the fibrous adsorbent which has also shown fast kinetics.

Abstract: The effect of slag treatment with Copper addition in silicon purification by metallurgical methods was examined in this paper. The microstructures and contents of Si-Cu alloy after slag refining were investigated by XRD and ICP, respectively. The majority phases in the Si-Cu alloy were Cu₃Si and Si. The partition ratio of boron (L_B) between slag and silicon was studied with and without Cu addition. Experimental results show that slag treatment with Cu addition can improve the L_B in CaO-SiO₂-CaF₂ slag system, where a maximum boron removal ratio of 85% could be achieved.

Abstract: An innovating slag system, Fe (OH)₃-SiO₂-CaF₂ system, was introduced in the metallurgical methods to purify silicon for photovoltaic application. The partition ratio of boron (L_B) between slag and silicon was studied under different mass ratio of slag to silicon and varying mass ratio of Fe (OH)₃ to SiO₂ under argon condition at 1873K. The distribution of impurity elements in silicon after slag refining was detected by scanning electron scope and electron probe micro analysis. Experimental results illustrated that the Fe-Si binary system could promote the L_B. Silicon was surrounded by amorphous slag. Impurity elements are concentrated in slag.

Abstract: A new slag system, Y2O3-SiO2-CaF2 system, was adopted in purification of Si for photovoltaic application. The partition ratio of boron (LB) between slag and silicon was studied under different mass ratio of slag to silicon and varying basicity at 1873K. Scanning electron scope and electron probe micro analysis were used to detect the distribution of impurity elements in silicon after slag refining. The experimental results show that the mass ratio of slag to silicon did not affect the trend of slag basicity with LB, and high mass ratio of slag to silicon would decrease LB. Silicon was surrounded by amorphous slag. Impurity elements are concentrated in slag. Yttrium oxide’s role in slag and kinetic analysis of boron removal are also discussed.

Abstract: The presence of boron compounds in waters increases in a continuous and parellel way to industrial development. Therefore, their harmful effects an living organisms also increases, especially on plants, since this element manifests an important micronutrient-toxic boron duality. Boron is widely distributed in the environment, mainly in the form of boric asid or borate salts. Generally speaking, this element is an important micronutrient for living organisms, but the range between deficiency and excess is narrow. For this reason, the World Health Organization (WHO) recommendsin ist Guidelines for Drinking-Water Quality, a maximum boron concentration of 0.3 mgL-1. The same norms are recommended when seawater is used as a source of water. The aim of this study to investigate the influence of different operation variables within the precipitation process of boron with magnesium hydroxide when boron stock solution is being treated. Operation variables are precipitant amount, stirring speed, contact duration, pH, temperature.

Abstract: The distribution of boron between solid silicon and melt Si-Al alloy (K_B) and the interaction coefficients between aluminum and boron in solid silicon were investigated by establishing the equilibrium between Si–B alloy and aluminum at 1623 K ~ 1723 K for 4 h and then quenching them to obtain the content of boron and aluminum in silicon and Si-Al melt. The results shown that the distribution coefficients of boron KB are 0.139~0.325 (1623K), 0.332~0.587 (1673K), 0.684~0.956 (1723K), and the interaction coefficients are 32.8±2.34 (1623K), 16.3±1.17 (1673K) and 8.2±0.6 (1723K).

Abstract: Alkalizer or coagulation and alkalizer technology were adopted to pretreat seawater in the study. Turbidity removal was investigated with different pH, mixing time,and mixing speed. The A was the best by contrasting alkalizer A, B and C. Turbidity removal was 99.4%. The effect of boron removal in the seawater was also studied. The results showed that the pH value has a great impact on the boron removal. The highest boron removal was 89% by alkalizer A under pH 11.The best reaction condition for turbidity removal : pH value 10.8,stirring rate 200r/min,reaction time 10 minutes and dosage of PAM 0.5 mg/L.