Effects of Specific Surface Area on Granulation Behavior of Vanadium Titano-magnetite Concentrate
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摘要: 研究了比表面积对钒钛磁铁精粉烧结制粒行为的影响。结果表明:钒钛磁铁精粉均以不规则形状为主, 部分为片状和球状结构, 且其比表面积与平均粒径呈负相关关系, 但不同种类的钒钛磁铁矿其颗粒表面的粗糙程度差异较大。在钒钛磁铁精粉粒度较细的情况下, 比表面积对钒钛磁铁精粉制粒后小球的均匀性影响较小, 且矿粉的颗粒形貌对制粒效率、制粒后小球的抗机械冲击能力和抗热粉化能力的影响远大于矿粉比表面积对上述三项指标的影响, 此时, 钒钛磁铁精粉制粒的限制性环节为其颗粒致密的结构和光滑的表面形貌。主要原因是钒钛磁铁精粉制粒中颗粒间黏附力弱, 且制粒后的小球在受机械冲击和热气流作用时, 其表层的黏附层容易脱落, 从而使得准颗粒小球结构破坏。因此, 钒钛磁铁矿制粒中增加一些颗粒形貌相对粗糙且亲水性能好的矿种, 或是通过掺入添加剂和对钒钛磁铁精粉预制粒, 然后再与其它烧结原燃料混合制粒, 增强其在制粒过程中的黏附能力, 从而提高制粒小球强度和热稳定性, 进而改善烧结料层的透气性。Abstract: Effects of specific surface area on the granulation behavior of the vanadium titano-magnetite concentrate(VTM) were investigated using micro-drum granulation equipment. The results show that the particle morphology of the VTM mainly present irregular shape,part of them are lamellar and globular structure.Their specific surface area and average particle size have a negative correlation,but there exist great difference in the particle surface roughness of different kinds of VTM. When the particle size of the VTM is small,there is no evident relationship between the specific surface area and uniformity index(UI),and the effects of the particle morphology on granulation index (GI),resistance index of the thermal disintegration(KI) and damage index(DI) are greater than the specific surface area.At this moment,the restrictive link for the VTM granulation are the compact structure and smooth morphology of the iron ore particles.The main reason is that the adhesion among VTM granules is relatively week,when the quasi-particles are subjected to the mechanical shock and hot air flow,the adhering layer of the quasi-particles is easy to fall off,leading to the destruction of the quasi-particle structure.In order to increase the adhesive capacity of iron particles,and improve the strength and thermal stability of the quasi-particles,the iron-bearing materials with relatively rough and good hydrophilicity or some kinds of additives should be added in the VTM granulation process.
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