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The mechanism of smelting reduction of chromite ore

铬铁矿矿石熔融还原机理

基本信息

批准号：
10650733
负责人：
MORI Katsumi
金额：
$ 0.7万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

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.

铬ィイD22ィエD2OィイD23ィエD2还原是铬铁矿生产铬铁的基本反应，也是从不锈钢冶炼脱碳过程中形成的渣中回收铬的基本反应。为了提高铬铁矿的还原效率，迫切需要从实践和理论上阐明其还原机理。因此，考察了氧化铬的形貌、还原剂种类、助熔剂种类和温度对还原速率的影响。在铁水中碳还原铬铁矿的反应在粉状状态下非常缓慢，但当在铁液中加入硅时，它优先用于还原生成二氧化硅，二氧化硅与矿石发生反应，促进矿石溶解成液态渣。结果，减排得到了显著的促进。在铬铁矿中加入二氧化硅、硼酸钠、CaO-SiOィイD22ィエD2渣等助熔剂，有利于形成液态渣，从而显著提高了铬ィイD22ィエD2OィイD23ィエD2的还原速度。用碳粉或硅粉还原熔渣和铬铁矿中的铬ィイD22ィエD2OィイD23ィエD2的表观活化能为200~300kJィイD_1~(-1)ィイD_2。结果表明，铬离子在铬铁矿中的扩散和溶解反应是铬还原的控制步骤，即铬离子在铬铁矿中的扩散和溶解反应。