高钛球团焙烧行为及其强化技术

Roasting behavior and enhancing technology of high-titanium pellets

研究了高钛球团的焙烧特征和固结行为.随着TiO_2含量的增加,球团焙烧难度增大,当TiO_2质量分数由10%增加至21%时,高钛球团所需预热时间由12 min延长至26 min以上,焙烧球强度由每个2486 N降低至每个1728 N.高钛球团由于FeTiO_3含量高,导致氧化速度慢、预热球氧化程度低,不利于焙烧固结时钛赤铁矿固溶体晶粒的长大,使得球团固结强度差.通过添加NaOH结合润磨工艺增大颗粒表面能和反应活性,促进了固相扩散,并生成少量低熔点化合物,有利于再结晶过程的扩散迁移,使Ti富集在Fe_2TiO_5中并促进钛赤铁矿晶粒长大,强化了高钛球团焙烧固结,可使预热时间缩短至16 min,球团强度提高至每个2141 N.

The roasting properties and solidification behaviors of high-titanium pellets were studied systematically in this paper.The results show that increasing the content of TiO2 in pellets can lead to a greater difficulty in their roasting process. When the content of TiO2 increases from 10% to 21%,the proper preheating time prolongs from 12 min to more than 26 min,while the strength of roasted pellets still decrease from 2486 N to 1728 N per pellet. The reason is that high-titanium pellets contain high content of FeTiO3,which leads to a lower oxidization velocity of magnetite and a lower pre-oxidization degree. This phenonmenon is further adverse to the growth and connection of haplotypite crystals,which finally worsen the consolidation strength of pellets. By simultaneously adding Na OH and applying the wet-grinding process,the surface energy and surface activity of ore particles increase,which contribute to improving the diffusion of solid phases and generating a small amount of low-melting-point compounds. These improvements are conducive to the diffusion of recrystallization and then facilitate the growth of titanium hematite grains and the enrichment of Ti in Fe2TiO5. As a consequence,the proper preheating time shortens to 16 min and the pellet strength increases to 2141 N per pellet for pellets containling21% of TiO2.