摘要:
采用失重法,从动力学角度分析了几种不同粒径印尼海砂球团氢气还原的规律。研究表明:在试验条件下,不同粒径球团在同一温度下的反应机理基本一致;还原温度低于900℃,整个反应由两个不同的限制性环节组成,反应开始阶段由化学反应控制,之后的反应由化学反应和内扩散共同作限制性环节;还原温度在900℃及以上,反应由三个不同的限制性环节组成,反应开始阶段由化学反应控制,中间阶段由化学反应和内扩散共同作限制性环节,反应后期由内扩散作为反应的限制性环节。不论在哪一种还原温度下,粒度小的球团矿在化学反应控速阶段反应最快,在内扩散控速阶段,内扩散阻力最小。
Abstract:
In this paper,the kinetic mechanism of reducing different sizes of Indonesia ironsand oxidized pellets by hydrogen was studied by means of gravimetrie method. The research mainly focuses on the kinetics. The results showed that the different reduction mechanism presents at different temperature. The restrictive step was composed of two different stages when reduction temperature was below 900 ℃,that is,the reduction begun with chemical reaction,and then was controlled by chemical reaction and intraparticle diffusion. When the temperature exceeds 900 ℃,The reduction mechanism was composed of three stages,that is,beginning with chemical reaction,followed by mixed-control of chemical reaction and intraparticle diffusion,and finally ended by intraparticle diffusion. At any reduction temperature,small oxidized pellets show a faster reaction speed at chemical reaction restrictive step,and have a smaller reaction resistance at intraparticle diffusion restrictive step.
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