鲕状赤铁矿深度还原过程中铁颗粒粒度和形貌特征分析

摘要

为研究鲕状赤铁矿和煤粉的混合球团矿经深度还原后铁颗粒的粒度和形貌特征,通过压块的方式模拟球团矿在高温下进行深度还原反应,并采用扫描电子显微镜(SEM)和工艺矿物学参数自动测试系统(BPMA)考察不同温度和时间下煤基球团矿经深度还原后金属铁颗粒的平均粒径、粒度分布和镜下形貌等特征变化.研究结果表明:随着还原温度升高或还原时间延长,铁颗粒粒径不断增大,且还原温度对铁颗粒长大的影响更显著;在不同还原条件下,粒度区间前20%中的铁颗粒数量占总体数量的60%~85%;铁颗粒的长大过程主要包括单个球形铁颗粒的析出与粗化,颗粒之间链接形成堆积铁颗粒集团并逐渐熔合均一化,最终生成稳定的大颗粒.%To study the characteristics of particle size and microtopography of oolitic hematite and pulverized coal in coal-based reduction, the process of coal-based reduction was simulated by squeezing block of oolitic hematite and coal. Average grain size, particle size distribution and microtopography of produced iron particles reduced at various temperatures and time were investigated via scanning electron microscope(SEM) and BGRIMM Process Mineralogy Analyzer (BPMA). The results show that grain size of metallic iron obviously increases with the increase of the reduction temperature and time, and reduction temperature has greater impact on iron grain growth. The number of iron particles in the first 20% particle size range accounts for 60%?85% in the total number of iron particles under different conditions. The growing process of iron particle is mainly as follows. Firstly, single spherical iron grain is separated out and coarsened; secondly, accumulational iron particles groups are formed by linking particles and then these groups are gradually fused and homogenized; stable and large iron particles are generated in the end.