1986 Fiscal Year Final Research Report Summary
Distribution Equilibria of Phosphorus and Sulfur between Liquid Iron and <Na_2> O Base Slags.
| Project/Area Number |
60550479
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | IRON AND STEEL TECHNICAL COLLEGE |
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Principal Investigator |
IWAI Hikoya Iron and Steel Technical College Department of Iron and Steel Engineering, Professor, その他, 教授 (60082377)
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| Co-Investigator(Kenkyū-buntansha) |
KUNISADA Kyoji Iron and Steel Technical College Department of Iron and Steel Technical College,, 鉄鋼工学科, 講師 (20105034)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Dephosphorization of Moten Steel / Desulfurization of Molten Steel / Phosphorus Distribution Ratio / Sulfur Distribution Ratio / Sの分配比 / 溶鋼の取鍋精錬 |
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| Research Abstract |
1. Introduction
In order to extend a market for steel materials, it is necessary to make steels high grade. Especially, the very low-phosphorus-steel and very low-sulfur-steel are strongly in demands. Desulfurization proceeds efficiently in the process of hot metal pretreatment, which has been fixed in every steel making plant, whereas dephosphorization is carried out in converter or ladle refining furnace. The ladle refining, in the stage of final steel making processes, is considered to be an advantageous process to obtain P+S<50ppm. In the present work, the possibility of the simultaneous dephosphorization-desulfurization by the <Na_2> O-based fluxes was investigated.
2. Experiment
The experiments were carried out in a Tammann furnace (static bath, Fe-P-S alloy/ <Na_2> O-CaO- <SiO_2> flux ratio = 30g/300g) and a high frequency induction furnace (stirring bath, ratio = 100g/1200g) in an atmosphere of Ar at 1600゜C. The obtained results were discussed from the thermodynamic point of view. The relationships among slag compositions ( <Na_2> O/ <SiO_2> , <Na_2> O/CaO ratios), oxygen potential of molten steels, degrees of dephosphorization and desulfurization, <C_P> and <C_S> were made clear. The stirring effect of molten steel was also discussed.
3. Results
(1) The <Na_2> O/ <SiO_2> ratio of final slags varied from 0.4 to 1.1. The degrees of dephosphorization and desulfurization increased with increasing in this ratio. (2) The <Na_2> O/CaO ratio of initial fluxes was set from 4 to 2. The degree of desulfurization decreased markedly, whereas that of dephosphorization was constant at a high lebel, with decreasing in this ratio. The ability of CaO to desulfurize molten steels was lower than that of <Na_2O> . The <Na_2O> -equivalence of CaO was determined to be 0.8 for dephosphorization and 0.3 for desulfurization. (3) By the stirring of molten steel, both of dephosphorization and desulfurization improved markedly.
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