还原时间对高料层碳热还原金属化率的影响

为了探讨PSH(paired straight hearth,对行直底炉)直接还原工艺的操作参数,进行了还原时间对高料层碳热还原金属化率影响的研究.试验结果表明:还原时间为50和60 min时,球团的金属化率较高,整个料层总的金属化率分别为57.31%和80.23%.但炉内还原60 min时,存在上层球团再氧化、热效率低、生产效率低等问题.采用热坩埚装料可以明显提高球团金属化率,尤其是底层球团.炉内还原50 min,采用热坩埚装料时,整个料层总金属化率可由冷坩埚装料的57.31%提高至85.24%.因此,以提高碳热还原金属化率为目的,建议采用热坩埚装料,炉内还原50 min.本试验的研究结果可为PSH工艺的开发提供理论依据.

Effects of Reducing Time on Metallization Degree of Carbothermic Reduction of Tall Pellets Bed

To explore the operation parameters of the direct reduction processing using the paired straight hearth furnace (PSH)， the effects of reducing time on metallization degree of carbothermic reduction of tall pellets bed are investigated in this work. The experimental results show that， when the reducing time is set to 50 and 60min， the metallization degree (MD) of the total pellets bed is 57.31% and 80.23%， respectively. However， there are some disadvantages in the case of 60min， such as re-oxidation of the pellets in the top bed， low heat efficiency， and low productivity. Charging with hot crucible can increase the MD of the pellets， especially for the pellets in the bottom bed. In the case of 50min， the MD of the total pellets bed increases from 57.31% charging with cold crucible to 85.24% charging with hot crucible. Therefore， the hot crucible charge and the 50min of reducing time are suggested for increasing the MD of carbothermic reduction of tall pellets bed， which could provide a guideline for developing the effective reduction process in PSH.