1999 Fiscal Year Final Research Report Summary
The mechanism of smelting reduction of chromite ore
| Project/Area Number |
10650733
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MORI Katsumi Kyushu university, Division of Eng., Professor, 工学研究科, 教授 (80037754)
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| Co-Investigator(Kenkyū-buntansha) |
森 克巳 九州大学, 工学研究科, 教授 (80037754)
SUN Haiping Kyushu university, Division of Eng., Asso. Researcher (20226616)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Chromium / Stainless steel-making / Chromium oxide / Molten iron / Reduction rate / Carbothermic reduction / Molten slag |
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| Research Abstract |
The reduction of CrィイD22ィエD2OィイD23ィエD2 is a basic reaction for ferro-chromium production from chromite ore and for chromium recovery from the slag formed during the decarburaization period of stainless steel-making. In order to increase the reduction efficiency of chromite ore, it was strongly desired to clarify its reduction mechanism from the practical and the theoretical points of view. So, the effects of morphology of chromium oxide, kinds of reductant and fluxes and temperature on the reduction rate were examined.
The results obtained as follows. The reduction of chromite ore by carbon in iron melt was very slow in a powder state but when silicon was added to iron melt, it was preferentially used for the reduction to form silica, which reacted with ore to promote the dissolution of ore into liquid slag. As a result, the reduction was remarkably promoted. The addition of fluxes such as silica, sodium borate and CaO-SiOィイD22ィエD2 slag to chromite ore favored for the formation liquid slag and then the reduction rate of CrィイD22ィエD2OィイD23ィエD2 was significantly promoted. Apparent activation energies of 200-300 kJ molィイD1-1ィエD1 were obtained for the reduction of CrィイD22ィエD2OィイD23ィエD2 in molten slag and chromite ore by carbon or silicon.
It was found from these results that the rate-determing step for CrィイD22ィエD2OィイD23ィエD2 reduction was the diffusion of Cr ion in chromite ore and the dissolution reaction.
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