Development of Reaction Model for Sinter by Examining Reduction Process of its Mineral Components

(1)用电子探针定量分析了还原前工业烧结矿中赤铁矿、铁酸钙、磁铁矿和炉渣的含量。在还原前和还原到磁铁矿阶段在1133 K的烧结矿的EPMA表面分析之间的比较表明，CF打破成磁铁矿和炉渣。用X射线内标法定量分析还原成磁铁矿过程中的烧结矿，结果表明，随着还原程度的增加，赤铁矿、CF和磁铁矿的含量发生了变化，CF在1033和1133 K还原，但在933和983 K几乎不还原。还原到磁铁矿阶段的样品的显微结构表明，CF在1033 K下被还原，但在983 K下不被还原。(2)在升温至1173 K的条件下，测量了赤铁矿-磁铁矿阶段的最终还原分数F_f，在此基础上测量了恒温下的最终还原分数F_f，两者的气体比CO/（CO+CO_2）= 0.20 ; CF在1003 K以上还原为磁铁矿，但在1003 K以下几乎不还原，在1003 K以下的温度范围F_f= 0.7时，在这个阶段的还原氧被假定为来自赤铁矿和CF。并给出了F_f/F_f'与还原温度的关系。e.其中T是获得F_f（K）的绝对温度。在773和873 K下，从0.20到磁铁矿稳定区上限的不同气体比率下，证实了CF在较低温度下的非还原性。(3)单颗粒逐步减少在753至1333 K的温度范围内，并考虑到上述事实的速率参数值进行了评估，化学反应速率常数和有效扩散系数的温度依赖性。

(1) Quantitative analysis of commercial sinter before reduction by EPMA gave the contents of hematite, calcium ferrite (CF), magnetite and slag. Comparison between EPMA surface analyses of sinter before reduction and reduced to magnetite stage at 1133 K suggests that CF breaks up into magnetite and slag. Quantitative analysis of sinter during reduction to magnetite by the X-ray internal standard method using the foregoing contents reveald variations in the amount of hematite, CF and magnetite with fractional reduction ; CF was reduced at 1033 and 1133 K but was hardly at 933 nor 983 K. Microstructures of samples reduced up to magnetite stage show that CF is reduced at 1033 K but not at 983K.(2) Final fractional reduction in the hematite to magnetite stage under rising temperature conditions up to 1173 K, F_f', was measured after measuring the one at a constant temperature, F_f, both as the gas ratio CO/(CO+CO_2) = 0.20 ; CF was reduced to magnetite at 1003 K or more but was hardly below 1003 K and in the latter temperature range F_f=0.7 when the oxygen reducible in this stage was assumed to be come from hematite and CF. And the ratio F_f/F_f' is given as a function of reduction temperature, i. e. where T is the absolute temperature to obtain F_f (K). Such non-reducibility of CF at lower temperatures was confirmed at different gas rations from 0.20 to the upper limit of the magnetite stable region at 773 and 873 K.(3) Single particles were reduced stepwise in a temperature range from 753 to 1333 K and rate parameter values were evaluated in consideration of the above facts ; temperature dependencies of chemical reaction rate constant and effective diffusivity are presented.