制粒准颗粒堆积行为的数值模拟

Numerical simulation on packing behavior of iron ore granules

制粒准颗粒的粒度组成是影响烧结生料层透气性的主要因素之一。通过配料操作、制粒工艺优化等措施能够在一定程度上调节制粒后准颗粒的粒度分布。为探讨准颗粒级配模式对烧结生料层床层结构的影响规律,对制粒准颗粒在烧结杯内的堆积行为进行了数值仿真。首先,在实验室条件下对1种烧结混合料进行了变含水量的常规制粒实验,实验结果表明:调节制粒含水量可以显著地改变准颗粒群的粒度组成,生料层透气性也随之得到调整。随后,基于刚性球体颗粒模型,运用离散单元法对准颗粒群的堆积行为进行了数值仿真。研究发现:准颗粒的级配模式对烧结杯堆积床层的模拟空隙率有显著的影响,在颗粒不发生显著塑性变形时,仿真所得的稳态空隙率与实验所得的生料层透气性指数有很好的线性正相关关系。

Particle size distribution of granules is one of the main factors influencing the permeability of the green packed bed.To some extent,by ore-blending operation and granulation optimization method,the particle sizes of the granules can be modified.In order to reveal the effect of size grading of the granules on the packed bed structure in sinter pot,conventional granulation on a sinter mixture with moisture content varied was carried out under laboratory conditions.From the experiments,the results show that optimal moisture content can remarkably improve the particle size distribution of the sinter mixture in granulation,as a consequence,the permeability of the green packed bed can be modified.Based on rigid sphere model for particles,the packing process of the granules into sinter pot was investigated by discrete element method（DEM）.Simulation results confirm that the size grading of the granules would significantly influence on the steady packed porosity.When the particles do not undergo significant plastic deformation,there is a good linear correlation between the simulated steady porosity and the green bed permeability.