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在氩气氛下,以石墨作还原剂,当温度为1100—1350℃时,用热重分析法(TGA),x-射线衍射分析法(XRD),光学显微镜检查,Scnning型电子显微镜(SEM),x-射线能耗分析法(EDAX)研究了南非马马特旺锰矿还原的动力学。显而易见,还原速率和还原程度随温度的升高,颗粒粒度的减小而提高。在还原初期,当还原时间高达4min时(相当于约30％的还原率),分别观察到铁锰高价氧化物(Mn_2O_3和Fe_2O_3)还原成MnO和FeO。这一阶段很可能受到固相之间界面层扩散过程的控制。对于这一扩散过程而言,其表现活化能为61.03kJ。金属化首先以铁无规则核化开始,随即绕颗粒内的MnO粒子而碳化。此外,在还原率约30％以后,还观察到硅酸盐相的形成。在温度为1350℃情况下,当还原率高达70％时,还原率可能受到氧化物相和气相之间化学反应的控制,为此计算出了活化能为153.32kJ。还原过程的后一阶段是进行MnO的还原,该MnO被碳化物或者硅酸盐相覆盖,与溶解于碳化物相(Mn,Fe)_5C_2的碳反应。就这一步骤而言,氧化物相中Mn~(2+)离子的扩散很可能为速率决定级,对此求出的表现活化能为310.4kJ.
Graphite was used as a reducing agent under argon atmosphere and the thermal gravimetric analysis (TGA), x-ray diffraction (XRD), optical microscopy and Scnning electron microscopy (SEM) , x-ray energy analysis (EDAX) study of South Africa Mamatite manganese reduction kinetics. Obviously, the reduction rate and the degree of reduction with increasing temperature, the particle size decreases. In the initial stage of reduction, the reduction of Fe2O3 to MnO2 and Fe2O3 were observed respectively when the reduction time was up to 4 min (equivalent to about 30% reduction rate). This phase is likely to be controlled by the diffusion of interfacial layers between the solid phases. For this diffusion process, its performance activation energy is 61.03kJ. Metallization first starts with random nucleation of iron and then carbonizes around the MnO particles in the particles. In addition, formation of a silicate phase was also observed after a reduction rate of about 30%. At a reduction temperature of 70%, the reduction rate may be controlled by the chemical reaction between the oxide phase and the gas phase at a temperature of 1350 ° C, for which an activation energy of 153.32 kJ was calculated. The next stage of the reduction process is the reduction of MnO, which is covered by the carbide or silicate phase and reacts with the carbon dissolved in the carbide phase (Mn, Fe) _5C_2. In this step, the diffusion of Mn 2+ ions in the oxide phase is likely to be a rate-determining step, and the expression activation energy determined for this is 310.4 kJ.