Precipitation Phase and Impurities Distribution of Metallurgical Grade Silicon by Vacuum Refining Followed Slag Treatment

Precipitation phase and impurities distribution of MG-silicon were investigated by vacuum refining followed by slag treatment, and the CaO-SiO2-CaF2 system was adopted for slag treatment. Contrasting the microstructure of precipitated phase in slag treatment with and without vacuum refining pretreated, it could be concluded that the composition of precipitated phases, obtained in MG-Si after vacuum refining followed slag treatment, only consisted of Ca-rich intermetallic silicide phases such as Si-Ca-Ni, Si-Ca-Fe and main impurity phase Si-Ca. And the vacuum refining could make an increase in concentration of the impurity Ti due to its low saturated vapor pressure and silicon loss, which was in favor of the interaction with the impurity B, resulting in the formation of TiB2 that could stay at the slag. Consequently, the vacuum refining could be regarded as an effective method for facilitating the removal of B from MG-Si with slag treatment.

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Effect of Na2O-SiO2 Slag Treatment on Hydrometallurgical Purification of Metallurgical Grade Silicon

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.420.139 ◽

2013 ◽

Vol 420 ◽

pp. 139-143 ◽

Cited By ~ 1

Author(s):

M. Fang ◽

C.H. Lu ◽

H.X. Lai ◽

L.Q. Huang ◽

J. Chen ◽

...

Keyword(s):

Comparative Analysis ◽

Acid Corrosion ◽

Intermetallic Phases ◽

Leaching Behavior ◽

Metallurgical Grade Silicon ◽

Metal Impurities ◽

Precipitated Phase ◽

Slag Treatment ◽

Corrosion Experiment ◽

Grade Silicon

The effects of Na2O-SiO2slag treatment on purification of metallurgical grade silicon by leaching with hydrogen fluoride have been investigated. A comparative analysis of microstructure evolution was carried out to examine the leaching behavior of impurities from metallurgical grade silicon. It was found that the distribution of metal impurities Al, Ca, Ti and Na, which co-deposited with Si and formed different intermetallic phases at grain boundaries, had manifest distinction between precipitated phase and silicon. Moreover, acid corrosion experiment results revealed that slag treatment improved the dissolution rate of metal impurities from metallurgical grade silicon as contrasted to that without slag treatment.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.949 ◽

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.

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Microstructural Characterization in Metallurgical Grade Silicon after Treatment by CaO-SiO2 and Na2O-SiO2 Slags

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.815.404 ◽

2013 ◽

Vol 815 ◽

pp. 404-408

Author(s):

Ming Fang ◽

Cheng Hao Lu ◽

Liu Qing Huang ◽

Hui Xian Lai ◽

Juan Chen ◽

...

Keyword(s):

Grain Boundaries ◽

Microstructural Characterization ◽

Metallurgical Grade Silicon ◽

Low Level ◽

Precipitated Phase ◽

Slag Treatment ◽

Grade Silicon

The microstructure and impurities distribution in metallurgical grade silicon with treated by CaO-SiO2 and Na2O-SiO2 slags were investigated. An exhaustive analysis of the transformation of precipitated phase at grain boundaries has been carried out. Prior to slag treatment, Si-Fe system intermetallic was the primary precipitated phase in metalllurgical grade silicon. After treated by CaO-SiO2 slag, Si-Ca system intermetallic became the main precipitated phase, such as Si-Ca, Si-Ca-Ti, Si-Ca-Al and Si-Fe-Ca. But Na2O-SiO2 slag had another result on refining metallurgical grade silicon; only Si-Fe-Ti phase was generated in precipitated phase and the low level of sodium in treated silicon was obtained.

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Study on a Quaternary Working Pair of CaCl2-LiNO3-KNO3/H2O for an Absorption Refrigeration Cycle

Entropy ◽

10.3390/e21060546 ◽

2019 ◽

Vol 21 (6) ◽

pp. 546 ◽

Cited By ~ 2

Author(s):

Yiqun Li ◽

Na Li ◽

Chunhuan Luo ◽

Qingquan Su

Keyword(s):

Heat Capacity ◽

Crystallization Temperature ◽

Saturated Vapor Pressure ◽

Saturated Vapor ◽

Specific Enthalpy ◽

Refrigeration Cycle ◽

Absorption Refrigeration ◽

Evaporation Temperature ◽

Corrosion Rates ◽

Specific Entropy

When compared with LiBr/H2O, an absorption refrigeration cycle using CaCl2/H2O as the working pair needs a lower driving heat source temperature, that is, CaCl2/H2O has a better refrigeration characteristic. However, the crystallization temperature of CaCl2/H2O solution is too high and its absorption ability is not high enough to achieve an evaporation temperature of 5 °C or lower. CaCl2-LiNO3-KNO3(15.5:5:1)/H2O was proposed and its crystallization temperature, saturated vapor pressure, density, viscosity, specific heat capacity, specific entropy, and specific enthalpy were measured to retain the refrigeration characteristic of CaCl2/H2O and solve its problems. Under the same conditions, the generation temperature for an absorption refrigeration cycle with CaCl2-LiNO3-KNO3(15.5:5:1)/H2O was 7.0 °C lower than that with LiBr/H2O. Moreover, the cycle’s COP and exergy efficiency with CaCl2-LiNO3-KNO3(15.5:5:1)/H2O were approximately 0.04 and 0.06 higher than those with LiBr/H2O, respectively. The corrosion rates of carbon steel and copper for the proposed working pair were 14.31 μm∙y−1 and 2.04 μm∙y−1 at 80 °C and pH 9.7, respectively, which were low enough for engineering applications.

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Effects of nanoparticles on hydraulic cavitation

MATEC Web of Conferences ◽

10.1051/matecconf/201824003004 ◽

2018 ◽

Vol 240 ◽

pp. 03004

Author(s):

Min-rui Chen ◽

Jin-yuan Qian ◽

Zan Wu ◽

Chen Yang ◽

Zhi-jiang Jin ◽

...

Keyword(s):

Vapor Pressure ◽

Saturated Vapor Pressure ◽

Saturated Vapor ◽

Geometric Model ◽

Pressure Ratio ◽

Perforated Plate ◽

Significant Parameter ◽

Operation Conditions ◽

Small Bubbles ◽

Crucial Condition

When liquids flowing through a throttling element, such as a perforated plate, the velocity increases and the pressure decreases. If the pressure is below the saturated vapor pressure, the liquid will vaporize into small bubbles, which is called hydraulic cavitation. In fact, vaporization nucleus is another crucial condition for vaporizing. The nanoparticles contained in the nanofluids play a significant role in vaporization of liquids. In this paper, the effects of the nanoparticles on hydraulic cavitation are investigated. Firstly, a geometric model of a pipe channel equipped with a perforated plate is established. Then with different nanoparticle volume fractions and diameters, the nanofluids flowing through the channel is numerically simulated based on a validated numerical method. The operation conditions, such as the temperature and the pressure ratio of inlet to outlet, are the considered variables. As a significant parameter, cavitation numbers under different operation conditions are achieved to investigate the effects of nanoparticles on hydraulic cavitation. Meanwhile, the contours are extracted to research the distribution of bubbles for further investigation. This study is of interests for researchers working on hydraulic cavitation or nanofluids.

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Density Determination of Cryogenic Liquids as a Function of Saturated Vapor Pressure

Advances in Cryogenic Engineering ◽

10.1007/978-1-4757-0528-7_30 ◽

1963 ◽

pp. 251-255 ◽

Cited By ~ 1

Author(s):

T. C. Shupert

Keyword(s):

Vapor Pressure ◽

Saturated Vapor Pressure ◽

Saturated Vapor ◽

Density Determination ◽

Cryogenic Liquids

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Porous Hydroxyapatite with Tailored Crystal Surface Prepared by Hydrothermal Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.284-286.353 ◽

2005 ◽

Vol 284-286 ◽

pp. 353-356 ◽

Cited By ~ 1

Author(s):

Koji Ioku ◽

Giichiro Kawachi ◽

Nakamichi Yamasaki ◽

Hirotaka Fujimori ◽

Seishi Goto

Keyword(s):

Aspect Ratio ◽

Vapor Pressure ◽

Hydrothermal Method ◽

Saturated Vapor Pressure ◽

Crystal Surface ◽

Saturated Vapor ◽

Pure Water ◽

Porous Hydroxyapatite ◽

Exposure Method ◽

The Mean

Porous plates of hydroxyapatite (Ca10(PO4)6(OH)2; HA) with about 0.5 to 5 mm in thickness and porous HA granules of about 40 µm to 1 mm in size with tailored crystal surface were prepared by the hydrothermal vapor exposure method at the temperatures above 105 °C under saturated vapor pressure of pure water. Porous HA plates with about 75 % porosity prepared at 120 °C were composed of rod-shaped crystals of about 20 µm in length. Porous HA granules prepared at 160 °C were also composed of rod-shaped crystals of about 20 µm in length with the mean aspect ratio of 30. These crystals were elongated along the c-axis. Rod-shaped HA crystals were locked together to make micro-pores of about 0.1 to 0.5 µm in size. Both of materials were nonstoichiometric HA with calcium deficient composition. These materials must have the advantage of adsorptive activity, because they had large specific crystal surface and much micro-pores.

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