【作者】 王强；

【导师】 范晓慧；

【作者基本信息】 中南大学 ， 钢铁冶金， 2012， 硕士

【摘要】 我国钒钛磁铁矿较为丰富,开采量居全国铁矿的第三位,主要分布在攀枝花—西昌等地。攀钢以钒钛磁铁精矿作为主要烧结原料,为充分利用自有资源,降低炼铁的成本并提高钒制品的经济效益,将加大钒钛磁铁精矿烧结的配入量。但钒钛磁铁精矿配比的提高将对烧结造成不利影响,因此有必要系统研究钒钛磁铁精矿的烧结性能,揭示钒钛磁铁精矿比例提高影响烧结指标的原因,并在此基础上开发强化烧结的技术措施。钒钛磁铁精矿比例提高对烧结适宜工艺参数及产量、质量指标的影响表明：随着钒钛磁铁精矿比例从0%增加到55%,烧结适宜的焦粉配比从5.0%降低到4.0%,适宜水分从8.50%降低到8.25%；烧结速度从23.05mm/min降低到18.21mm/min,利用系数从1.55t/(m2.h)降低到1.21t/(m2·h),成品率从73.18%降至69.04%,转鼓强度从62.93%降低到56.80%；烧结矿还原度有降低的趋势,而软熔和滴落区间有变宽的趋势,渣铁分离难度增大。表明提高钒钛磁铁精矿比例恶化了烧结产质量指标和冶金性能。通过研究钒钛磁铁精矿对混合料制粒和烧结成矿的影响,揭示了钒钛磁铁精矿影响烧结的机理：钒钛磁铁精矿制粒性能表明,由于钒钛磁铁精矿粒度较粗,其颗粒表面平整光滑,多呈扁平状,因而其制粒性能差；随着钒钛磁铁精矿比例的增加,制粒后混合料的平均粒度从4.89mm降低到2.60mmm,-1mm粒级含量从0.05%增加到6.00%,制粒小球形状系数减小,使得烧结料层透气性从1.43J.P.U降低到1.22J.P.U,因而降低了烧结垂直速度。钒钛磁铁精矿成矿性能表明,钒钛磁铁精矿在1300℃时铁酸钙生成量达到最大,温度继续提高,则钙钛矿大量生成,而铁酸钙含量减少,因此钒钛磁铁精矿适宜的烧结温度范围窄,以1300℃左右为宜；钒钛磁铁精矿中的TiO2、Al2O3和MgO都可提高烧结物料的熔点,使得随着钒钛磁铁精矿比例的提高,混合料液相开始生成温度提高,液相生成量减少,因而钒钛磁铁精矿烧结液相生成难度大。对钒钛烧结矿矿物组成和显微结构的研究表明,随着钒钛磁铁精矿比例的提高,烧结矿中钙钛矿含量增加,铁酸钙含量减少。且骸晶与散骨结构的赤铁矿含量增加,铁酸钙的形态逐渐由针状向柱状、粒状转变；由于液相生成难度增大,性脆的钙钛矿含量增加,以及强度好的针状铁酸钙含量减少,使得烧结矿的成品率和转鼓强度随着钒钛磁铁精矿比例的提高而降低。钒钛磁铁精矿烧结强化技术的研究表明：采用润磨和高压辊磨预处理钒钛磁铁精矿,减小了颗粒粒度、增大了表面活性,其制粒后混合料平均粒度增大、制粒小球形状系数提高,使得混合料透气性得到改善,当采用高压辊磨预处理钒钛磁铁精矿2次,与未处理相比,透气性从1.22J.P.U提高到1.47J.P.U,烧结速度从18.22mm/min提高到21.15mm/min；提高生石灰的配比或使用CaO含量高的生石灰,制粒后混合料中-3mmm含量依次减少,平均粒度呈增大的趋势,而透气性得到提高。与生石灰-1#相比,采用生石灰-4#,透气性从1.22J.P.U提高到1.40J.P.U,烧结速度从18.22mm/min提高到21.44mm/min。添加复合粘结剂制粒后混合料中-3mm含量减少,平均粒度提高,使得透气性得到改善,添加0.2%复合A,与未添加粘结剂相比,透气性从1.22J.P.U提高到1.41J.P.U,烧结速度从18.21mm/min提高到20.94mm/min。预制粒保证普通矿中能生成铁酸钙,得到了有利于烧结矿强度的微观结构,当钒钛磁铁精矿部分R为2.03,与未预制粒相比,转鼓强度从56.80%提高到59.54%。采用熔点较低的褐铁矿替代混合料中配比较大、熔点较高的澳矿可降低混合料熔点,促进液相生成,当采用FMG矿完全替代澳矿,与未替代相比,转鼓强度从更多还原

【Abstract】 The resources of vanadium-titanium magnetite concentrates(VTC) in China are rich which rank third in exploitation of national iron ore, and mainly located in Pan-Xi region. Pan Steel mainly used VTC as sintering raw material. In order to make fully use of its own iron resources, lower production costs and improve economic benefits of Vanadium products, Pan Steel intends to improve VTC amount in sintering material. However, increase of VTC proportion is disadvantage for sinter. Therefore, it’s necessary to study the properties of VTC sintering, find out the effect of VTC proportion on sinter performance, and obtain strengthening methods of VTC sintering on that basis.Study on VTC suitable parameters and sintering properties shows that, with the increase of VTC from0%to55%, the suitable granulation moistures increase from8.50%to8.25%and coke proportions reduce from5.0%to4.0%, the sintering velocity reduce from23.05mm/min to18.21mm/min, specific productivity decrease from1.55t/(m2·h) to1.21t/(m2·h), yield reduce from73.18%to69.04%, tumbler index lessen from62.93%to56.80%. Reduction degree of sinter decrease, melting and dripting zone widen lead that slag and iron is hard to separate. In a word, sinter qualities and metallurgical properties become worse.The VTC granulation and mineralization properties are studied which proclaimsthe mechanisms of VTC affecting sintering:The results of VTC granulation properties show that, VTC has coarse particles, smooth surface and flat shape, which results in its bad granulation properties. With increasing VTC proportion, average particles of mixture decrease from4.89mm to2.60mm, thin size-fraction below lmm increase from0.05%to6.00%, roughness of granulation ball increase, and form factor of particles become smaller, permeability decrease from1.43J.P.U to1.22J.P.U, which lead sintering velocity lower.The results of VTC mineralization show that, calcium ferrite generate maximum at1300℃in VTC sintering, with temp. rising, perovskite increase and calcium ferrite lessen. So VTC sinter suitable temp. range is fairly narrow, and the optimal temperature is about1300℃. TiO2, MgO and Al2O3in VTC can improve melting point, lead that liquid phase formations of mixture become harder with the increase of VTC.The results of mineral composition and microstructure show that, with the increase of VTC, the content of perovskite gradually increase, calcium ferrite decrease, the amount of dendrites and scattered bone structure of hematite increase, and the shape of calcium ferrite from the needle-like gradually develop into the column-like and granulous-like. Liquid phase is hard to form, fragile perovskite increase, and needle-like calcium ferrite which has highly intensity lessen, these lead that tumbler index and yield reduce with the increase of VTC.The results of strengthening methods for VTC sintering show that, wet grinding and high-pressure roll press precondition VTC can reduce particle size, increase surface activity. The average particle and form factor of particles are improved which leads to a better permeability. Compare with untreated material, permeability increase from1.22J.P.U to1.47J.P.U, sintering velocity improve from18.22mm/min to21.15mm/min when used twice of high-pressure roll press precondition. Rise burntlime amount or use higher content of CaO can gradually reduce content of below3mm particle, improve average particle and permeability. Compare with burntlime No.1, permeability increase from1.22J.P.U to1.40J.P.U, sintering velocity improve from18.22mm/min to21.44mm/min with use of burntlime NO.4. Addition complex binder can reduce content of below3mm particle, improve average particle and permeability. Compare with no binder, permeability increase from1.22J.P.U to1.41J.P.U, sintering velocity improve from18.22mm/min to20.94mm/min. pregranulation can insure normal iron ore generating fairly calcium ferrite, get suitable microstrure. Compare with untreated material, tumbler index improve from56.80%to59.54%when basicity of VTC pregranulation part was2.03. Substitute limonite with lower melting point for Australia ore with higher melting point can facilitate the generation of liquid phase. Tumbler index improve from56.80%to59.51%when Australia ore was totally replaced by FMG ore.更多还原