微波加热褐铁矿的脱水反应动力学

研究了微波加热褐铁矿的脱水过程，利用SEM和XRD分析了褐铁矿脱除结晶水前后矿相的转变. 根据升温和失重变化曲线，采用微分法和积分法计算褐铁矿结晶水热分解过程的动力学参数，确定了褐铁矿在微波加热条件下脱水的反应机制. 结果表明，该矿的化学式为2Fe2O3·3H2O；在脱去结晶水后转变为赤铁矿，Fe2O3和SiO2含量增加，晶粒尺寸减小，矿相相对变纯. 褐铁矿在470~650 K内脱水反应的表观活化能为17.39~19.33 kJ/mol，低于常规加热脱水反应的活化能，说明微波加热能降低反应的活化能；且其脱水反应机理符合Maple单行法则，属于随机成核和随后生长的化学反应控制.

Dehydration Reaction Kinetics of Limonite under Microwave Heating

The dehydration process of limonite under microwave heating was studied, and the change of mineral phases in limonite analyzed by SEM and XRD before and after removal of crystalliferous water. Then, according to the temperature-rising and weight loss curves, the kinetic parameters of thermal decomposition of crystalliferous water in limonite were calculated by differential method and integral method, the dehydration reaction mechanism of limonite by microwave heating was determined. The results showed that the chemical formula of limonite was 2Fe2O3·3H2O, limonite became hematite after removal of crystalliferous water, and the content of Fe2O3 and SiO2 increased, the grain size of iron ore decreased, mineral phase became relatively pure. The apparent activation energy of dehydration reaction was 17.39~19.33 kJ/mol in 470~650 K, lower than that by conventional heating, which indicated that microwave heating was favorable for lowering the reaction activation energy; and the reaction mechanism accorded with Maple single rule, belonging to the chemical reaction control of random nucleation and then growth.