铁精粉原料特性及其对熔剂性球团冶金性能的影响

CHARACTERISTICS OF IRON CONCENTRATE POWDER RAW MATERIALS AND THEIR INFLUENCE ON THE METALLURGICAL PROPERTIES OF FLUX PELLETS

优质熔剂性球团的生产对铁精粉原料条件要求较为严格,国内外各种球团铁精粉资源在化学成分、粒度组成、微观形貌和成球性能等方面差异较大,为生产出合格的熔剂性球团,针对不同铁精粉原料特性,设计了5种配矿方案,依托624 m~2球团带式焙烧机进行试验,摸索铁精粉种类对熔剂性球团冶金性能的影响。结果表明,不同配矿方案下熔剂性球团抗压强度较高,均在2 600 N以上,还原膨胀指数较低,均在12.5%以下;高SiO_(2)含量铁精粉使用比例升高会使球团软熔温度降低,区间变宽;大部分赤铁矿精粉焙烧过程中再结晶困难,尺寸偏小,且与液相粘结在一起,加剧了球团内部晶体结构的不均匀程度;粗颗粒铁矿粉会导致造球过程中混合料成球性能变差,且产生偏析,影响球团矿相结构的均匀性,导致低温还原粉化性能变差。球团结构不均匀主要表现在赤铁矿晶粒尺寸大小不均匀,气孔尺寸差异较大,液相分布不均匀。铁矿粉细磨后,偏析现象明显减少,内部结构更加均匀,熔剂性球团冶金性能明显改善。

The production of high-quality flux pellets has strict requirements for iron concentrate powder raw materials,and various pellet iron concentrate resources at home and abroad vary greatly in terms of chemical composition,particle size composition,microscopic morphology and spherical properties,in order to produce qualified flux pellets,five ore blending schemes are designed for different characteristics of iron concentrate raw materials,relying on 624 m 2 pellet belt roaster to test and explore the influence of iron concentrate powder types on the metallurgical properties of flux pellets.The results showed that the compressive strength of flux pellets was higher under different blending schemes,all above 2600 N,and the reduction expansion index was low,all below 12.5%.The increase of the proportion of iron concentrate powder with high SiO 2 content will reduce the soft melting temperature of the pellets and widen the interval.Most of the hematite concentrate is difficult to recrystallize during the roasting process,the size is small,and it is bonded with the liquid phase,which aggravates the unevenness of the crystal structure inside the pellet.Coarse iron ore powder will lead to poor spherical performance of the mixture during the pelletizing process,and cause segregation,which will affect the uniformity of the pellet phase structure and lead to poor low-temperature reduction pulverization performance.The uneven structure of the pellets is mainly manifested in the uneven grain size of hematite,the large difference in stomatal size,and the uneven distribution of liquid phase.After fine grinding of iron ore powder,the segregation phenomenon is significantly reduced,the internal structure is more uniform,and the metallurgical performance of flux pellets is significantly improved.