真空镧热还原Sm_2O_(3)过程床层传热对钐提取率的影响

Effects of Heat Transfer of Pellets Bed on Samarium Extraction Rate by Vacuum Thermal Reduction of Sm_(2)O_(3) with Lanthanum

Sm是生产钐钴永磁材料的重要原料,其采用真空镧热还原Sm_(2)O_(3)制备。Sm的生产过程周期长、生产效率低。采用数值方法研究了真空镧热还原Sm_(2)O_(3)过程团块床层传热对Sm提取率的影响。结果表明提高加热温度能够有效提高Sm的提取率;床层存在较大的温度梯度,越靠近中心区域温度越低,还原反应速度越慢,物料的还原率越低。辐射传热对床层温度影响较大,改变团块堆装方式有助于强化辐射传热。采用立方堆积的床层能够有效提高还原率,比斜方紧密堆积的床层还原率提高10%。立方堆积的床层装料量少、原料利用率高,单位体积床层产生Sm的质量与斜方紧密堆积的床层相当。

Samarium is one of raw materials for producing samarium-cobalt permanent magnet,which is prepared by vacuum thermal reduction of Sm_(2)O_(3) with La.Samarium has a long production cycle and a low production efficiency.In the paper,the effects of heat transfer of pellets bed on Sm extraction rate by vacuum thermal reduction of Sm_(2)O_(3) with La were studied by numerical methods.The results show that the reduction rate of Sm is improved effectively by increasing temperature.As a result of a large temperature gradient in the pellets bed,the closer to the central area,the lower the temperature is,the slower the reaction rate is,and the lower the reduction ratio is.Radiation heat transfer has a great influence on the bed temperature,which is enhanced by changing the ways of pellets packing.The reduction ratio is increased effectively in the cubic packed bed,which is 10%higher than that in the rhombic packed bed.Although the cubic packed bed has less charge,the utilization rate of raw materials is higher and yields of Sm in the bed per volume are almost equal as that in the rhombic packed bed.