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采用微波失重在线检测装置和XRD分别分析了褐铁矿与生物炭升温至923 K的失重变化及微波焙烧前后的矿相变化;同时基于褐铁矿微波还原焙烧升温失重曲线,采用Achar–Brindley–Sharp–Wendworth微分法和Coats–Redfern积分法,计算了褐铁矿在不同温度段的反应动力学参数.结果表明,褐铁矿与生物炭在923 K的还原温度下转变为磁铁矿,同时生成少量的硅酸亚铁(Fe2Si O4);其微波还原焙烧过程分为3个阶段进行,在366~470 K,反应的表观活化能(E1)分别为30.7和26.3 k J/mol,反应机理符合反应级数函数,属于化学反应控制;在470~650 K,表观活化能(E2)分别为40.3和33.1 k J/mol,反应机理符合Avrami–Erofeer函数,是随机成核和随后生长的化学反应控制;在650~825 K,表观活化能(E3)分别为52.4和52.9 k J/mol,反应机理符合Zhuralev–Lesokin–Tempelman函数,属于三维扩散控制.
The changes of weight loss of limonite and biochar when heated to 923 K and the changes of mineralogical phase before and after microwave roasting were analyzed by on-line microwave weight loss testing equipment and XRD respectively. Meanwhile, based on the Achar-Brindley- Sharp-Wendworth differential method and Coats-Redfern integral method were used to calculate the reaction kinetics parameters of limonite at different temperatures.The results showed that limonite and biochar were transformed into magnetite at 923 K reduction temperature, A small amount of ferrous silicate (Fe2SiO4) was formed. The microwave roasting process was divided into three stages. The apparent activation energy (E1) of the reaction ranged from 366 to 470 K were 30.7 and 26.3 kJ / mol respectively. The reaction The mechanism is in line with the reaction order function, which belongs to the chemical reaction control. The apparent activation energy (E2) is 40.3 and 33.1 kJ / mol at 470-650 K respectively. The reaction mechanism is in accord with the Avrami-Erofeer function and is random nucleation and subsequent growth The apparent activation energy (E3) was 52.4 and 52.9 kJ / mol at 650-825 K, respectively. The reaction mechanism was in accordance with the Zhuralev-Lesokin-Tempelman function and was controlled by three-dimensional diffusion.