| Project/Area Number |
60850124
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
金属精錬・金属化学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SANO Nobuo Professor, The University of Tokyo, Faculty of Engineering, 工学部, 教授 (50010749)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Kichiya Research Associate, The University of Tokyo, Faculty of Engineering, 工学部, 助手 (00092247)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1985: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | Slag / Basicity / Carbonate capacity / CO_2 solubility / CaO-CaF_2-SiO_2 flux / Na_2O addition / Silicon refining / 強塩基性フラックス / 高精錬能スラグ |
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| Research Abstract |
The CO_2 solubilities were measured for the various kinds of slag systems such as CaO-Al_2O_3, CaO-CaF_2, BaO-BaF_2, CaO-SiO_2-CaF_2 and CaO-SiO_2-CaF_2-Na_2O etc. and carbonate capacities of these slags were calculated. It is found that the CO_2 solubilities can be a good measure of slag basicity in the limited range of slag composition. The good relationships between carbonate capacities and phosphate or sulfide capacities, which are the measure of dephosphorization or desulfurization capability of slag, were observed. Using the carbonate capacity as a index of refining capability for various fluxes, new fluxes whith refining capacities are very high were developed. As a result, a addition of a small amount of Na_2O to CaO-CaF_2-SiO_2 fluxes increases the refining capacity significantly. Experiments for the removal of various impurities from hot metal were conducted by using this flux. Vanadium, niobium and titanium as well as phosphorus and sulfur were removed from hot metel to flux with a addition of a small amount of Na_2O, retaining the manganese in the hot metal. Since the refining capacities for the BaO-BaF_2 system are estimated to be vary large from the carbonate capacities, the effect of a BaO addition to CaO-CaF_2-SiO_2 fluxes on the phosphorus partition was investigated. The phosphorus partitions. namely phosphate capacities, increase with increasing BaO content in flux. Since the removal of boron from molten silicon is difficult according to the conventional method, experiments were conducted in order to investigate whether the highly basic fluxes are effective for removing boron in molten silicon or not. The treatments with MgO-CaO-SiO_2 and BaO-CaO-SiO_2 fluxes decrease the boron content in silicon. It is found that there is a possibility to develop a new refining process which provide cheaper silicon for solar cell from crude metallic silicon than that refined by the conventional process.
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