生物质用于转底炉直接还原工艺研究

为了探讨生物质还原剂用于生产金属化铁的可行性,针对转底炉直接还原工艺,从金属化率、抗压强度和体积收缩率三方面入手,分析了竹炭、木炭、秸秆纤维等3种生物质还原剂以及传统还原剂煤粉对含碳球团还原效果的影响。试验结果表明,生物质能够替代传统还原剂用于转底炉直接还原工艺。与传统还原剂相比,生物质还原剂在含碳球团金属化率方面的影响较小,但不同生物质对含碳球团强度和体积收缩率等方面的影响较大。秸秆纤维含碳球团的强度相对较高,但竹炭和木炭含碳球团的强度较低,需在较高温度下(1 300℃)焙烧才能达到后续生产要求;使用竹炭作还原剂的球团前期膨胀较其他还原剂更为严重,直接导致其高温区体积收缩率较小,从而影响含碳球团的强度和热量传递,需与其他还原剂搭配使用。

Application of biomass to the RHF direct reduction process

By considering the rotary hearth furnaces direct reduction process,using bamboo charcoal, charcoal,straw fiber and coal as reductants,the experimental study on the influence of reduction has been conducted from metallization rate,compressive strength and volumetric shrinkage.The results show that biomass reductants can replace traditional reductants used in the RHF direct reduction process.Compared with traditional reductants,biomass reductants have less affect on metallization rate,but different biomass reductants have large influence on strength and volumetric shrinkage of pellets.The compressive strength of pellet with straw fiber is relatively higher,and the compressive strength of pellets with charcoal or bamboo charcoal is low,but it can be improved at higher temperature (1 300 ℃)for reaching the production requirement.Using bamboo charcoal as reductant will lead to the swelling of pellets in the beginning stage,and this situation will make the volumetric shrinkage at high temperature lower,which will affect the strength of pellets and the heat-transfer between different material layers.Thus it would be better that bamboo charcoal should be used with other reductants.