碱金属盐对赤铁矿球团渗碳效率的影响

Effect of alkali salt on carburizing efficiency of hematite pellets

赤铁矿是一种制备碳化铁的优质含铁原料,但是目前存在渗碳效率低下的问题。为了提高赤铁矿的渗碳效率,在赤铁矿中加入碱金属盐,并借助X射线衍射(XRD)、高频红外碳硫分析仪和扫描电子显微镜等揭示碱金属盐在赤铁矿球团渗碳过程中的作用机理。结果表明,碱金属盐(Na_(2)CO_(3))能够促使致密的赤铁矿颗粒转变为疏松多孔的铁矿物颗粒,强化铁矿物的晶格畸变,提高CO在金属铁和碳化铁表面的吸附和分解能力,从而改善赤铁矿球团还原和渗碳效率;此外,预热处理是一种十分有效的强化Na_(2)CO_(3)添加剂作用的方法,不仅可以强化铁矿物的晶格畸变,还可以增强Na+离子的强化作用,显著提高赤铁矿球团的渗碳效率。当赤铁矿球团添加了质量分数为3%的Na_(2)CO_(3)并在1000℃预热15 min后,球团的渗碳指数从13.23升高到28.99。研究结果可为提高赤铁矿的渗碳效率提供参考。

Hematite is a kind of high-quality iron bearing material for the preparation of iron carbide,but there is a problem of low carburizing efficiency.In order to improve the carburizing efficiency of hematite,alkali salt were added to hematite.The mechanism of alkali salts in the carburizing process of hematite pellets was investigated using X-ray diffraction(XRD),high-frequency infrared carbon-sulfur analyzer and scanning electron microscope.The results show that the alkali salt(Na_(2)CO_(3))can promote the transformation of dense iron ore particles into loose porous iron ore particles,strengthen the lattice distortion of iron ore,improve the adsorption and decomposition ability of CO on the surface of iron and iron carbide,so as to improve the reduction and carburization efficiency of hematite pellets.In addition,preheating treatment is very effective method to enhance the effect of Na_(2)CO_(3)additive.Preheating treatment can not only strengthen the lattice distortion of iron ore,but also enhance the strengthening effect of Na+,which significantly improves the carburizing efficiency of hematite pellets.After preheating at 1000℃for 15 min,the carburization index of carburized pellets made from hematite containing 3%Na_(2)CO_(3)increased from 13.23 to 28.99.The research results can provide reference for improving the carburizing efficiency of hematite.