摘要
利用热重分析法探索了碳酸钠、硼砂和氟化钙3种添加剂对褐铁矿煤基直接还原行为的影响。结果表明,3种添加剂都能使褐铁矿球团在还原过程中失重率增加;3种添加剂都可以降低褐铁矿球团达到最大反应速率时的温度,最低温度依次为984℃、964℃和986℃;硼砂使得褐铁矿球团最大反应速率提高显著,提高幅度为0.29%/min,碳酸钠和氟化钙为0.1%/min和0.06%/min,硼砂的还原效果最优。3种添加剂的强化还原机理为:碳酸钠可以增强碳的气化反应以及产生碱金属效应;硼砂有助于还原过程中原子的传输;氟化钙改善还原动力学条件,促进离子间的相互扩散。
Effects of 3 additives sodium carbonate,borax,calcium fluoride,on the coal-based direct reduction behaviors of limonite were explored with a thermogravimetric analysis(TG). The analysis of the TG and DTG curves showed that three additives can bring in an increased mass loss ratio for limonite pellets during the reduction,and result in limonite reaching the maximum reaction rate at a lower temperature,respectively,of 984 ℃,964 ℃ and 986 ℃. It is shown that an addition of borax resulted in the maximum reaction rate for the limonite pellets during reduction process increased by 0. 29%/min,while an addition of sodium carbonate and calcium fluoride only increased it by 0. 1%/min and 0. 06%/min,respectively,indicating borax with an optimal reduction effect. The mechanism for the reduction of limonite intensified by three additives includes that an addition of sodium carbonate can enhance the gasification reaction of C,resulting in an alkali metal effect; an addition of borax can benefit the atom transmission during the reduction process; and an addition of calcium fluoride can improve the kinetic conditions for reduction reaction,thus promoting the diffusion among ions.
引文
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