提升宣钢球团矿还原性的研究与实践

球团矿良好的冶金性能对高炉节能减排具有十分积极的促进作用。通过对宣钢球团矿微观结构进行研究,发现其还原性偏低的主要原因为内核区域氧化不完全,FeO质量分数偏高。采取细化精粉成分管控、优化球团生产工艺参数等措施,有效缓解了球团矿表层再结晶的过分发展,促进内核区域磁铁矿的充分氧化,并显著降低FeO质量分数,有效消除液相夹芯,可实现球团矿还原性的明显提升。     

改善高炉球团矿还原性技术措施

球团矿作为高炉炼铁的主要原料,其冶金性能的好坏对高炉炼铁影响较大,并且对高炉提产降耗发挥着重要作用。一般高炉要求球团矿还原度60%,而河钢宣钢球团矿还原度在55%～58%,与先进企业相比存在一定差距。从原料、设备、工艺参数等方面进行梳理,针对系统存在的问题制定了整改措施,并逐项落实。2018年球团矿还原度明显改善,为高炉指标优化提供了良好的原料条件。     

冷固结球团矿的生产试验

为了开发一种工艺简单.投资少,能耗低,环境污染小的新型造块工艺,宣钢、钢研总院、合肥炮院合作进行了冷固结球团矿的生产试验,在试验室完成复合粘结剂的开发、压球工艺条件试验的基础上,设计并建成了一条年产3万吨冷结球团矿的生产线。首批生产了700吨冷结球团矿,在宣钢一炼300m~3的2~#高炉上进行配用试验,炉况顺     

宣钢球团矿质量攻关

2015年1月~6月,球团矿质量出现阶段性波动,FeO含量升高,还原性降低,球团矿整体质量变差。为改善球团矿质量,宣钢从原料结构优化、工艺操作、设备检修和维护等方面采取改进措施,取得了明显效果,球团矿质量大幅度改善,为后续球团生产提供了参考。     

宣钢高炉含铁炉料熔滴性能

对宣钢高炉炉料结构进行了熔滴性能试验研究。单矿的熔滴试验结果表明:宣钢常用的2种烧结矿软化性能较好,但滴落性能较差,1 520℃仍未滴落;3种球团矿中自产球总体熔滴指标最好但软化区间最长(313℃);2种块矿中PB矿开始软化温度最低软熔区间最长,试验中未能滴落。蒙古矿软熔性能较好,但滴落温度高达1 518℃。通过对15种配矿方案进行的熔滴试验,结果表明:降低烧结矿配比,提高PB矿比例可改善炉料的熔滴性能。在试验条件下,配矿方案为"烧结矿68%+球团矿16%+PB矿16%"的炉料结构熔滴性能最佳。     

新型有机粘结剂在球团生产中的应用

针对球团生产使用传统有机粘结剂存在的问题,开发了一种新型无土有机粘结剂及其造球专用立式混匀设备,并申请了专利.该技术在宣钢20万t/a回转窑球团生产线上应用后,结果表明:新型粘结剂完全可以取代膨润土,有效提高球团矿铁品位;同时预热球强度满足回转窑生产要求,球团矿冶金性能也能满足一般高炉要求.     

冷固结球团矿的研究和应用

宣钢等单位合作开发了铁精粉冷固结矿球团生产工艺。工业试验表明，冷结球团矿具有抗压强度高、冶金性能好等特点。在高炉上应用效果良好。研究还发现了冷球加碳，可使还原性大为改善，为高炉节焦增铁提供了新途径。     

宣钢炼铁厂球团矿配加有机黏结剂生产实践

介绍了宣钢炼铁厂在链篦机-回转窑球团矿生产过程中配加有机黏结剂的试验过程，并总结了不同配加量对球团工艺操作及产质量指标的影响，且达到最佳配量时能够提高球团矿品位，降低SiO2含量。     

链篦机—回转窑工艺配加含铁有机粘结剂试验

介绍了宣钢炼铁厂链箅机—回转窑球团矿生产线配加含铁有机粘结剂代替膨润土生产球团矿的试验方案。基准试验方案为膨润土配比1.8%;部分代替方案为膨润土0.5%+粘结剂0.6%、膨润土0.8%+粘结剂0.6%;全部代替方案为粘结剂配加0.9%~1.2%。综合球团矿的各项技术指标,认为膨润土0.5%+粘结剂0.6%的配料方案效果最好。     

宣钢1260m~3高炉炉料结构的优化

宣钢8号高炉炉料结构经过了三个阶段的变化,目前高炉使用的高碱度烧结矿配加竖炉球团矿和澳矿的炉料结构是较合理的炉料结构。     

宣钢烧结生产的技术进步

介绍了近几年宣钢第二炼铁厂依靠科技管理,强化原料综合利用和加快工艺技术创新的情况,使烧结、球团技术经济指标得到提高,为宣钢实现可持续发展打下了坚实基础。     

烧结球团配加镁质添加剂的试验

烧结球团配加镁质添加剂后,提高了球团矿中的MgO含量,酸性球团矿的软化性能得到改善,使高炉内软熔带变窄,炉内压差降低,有利于高炉顺行,吨铁综合成本降低14.42元.     

Mill scale as a potential additive to improve the quality of hematite ore pellet

Hematite pellet is required to be indurated at very high temperature to achieve its good strength as there is no exothermic heat of oxidation unlike magnetite. As mill scale contains mainly FeO and Fe₃O₄, any minor amount of its addition in pellet can provide in situ heat and enhance diffusion bonding and sintering. In this study, the mill scale generated in steel plant is added as magnetite input in hematite pellet both in acidic and in basic condition. It has been found that in fluxed pellet, mill scale can improve the properties of pellet. In acidic pellet, the induration temperature has been reduced to a great extent (1250–1275°C) and all properties have been found to be improved due to the addition of 15% mill scale. Mill scale shows enough potential to eliminate the flux addition in producing blast furnace quality pellet from hematite ore. Thus, the flux free acidic pellet has been developed even at very low temperature (1275°C) of induration.     

降低10m~2竖炉膨润土用量的生产实践

在铁矿资源日趋短缺的条件下,提高球团矿品位可在一定程度上降低炼铁成本,降低膨润土消耗是提高竖炉球团矿品位的途径之一。分析了河北敬业集团10 m2竖炉膨润土消耗偏高的原因,通过严格原料管理、工艺控制、加强对原料水分的控制、选用适合所用球团矿原料特点的膨润土等措施,吨矿膨润土用量由23 kg降低到16 kg,球团矿的品位达到了63.5%,高炉综合入炉品位提高0.255%。     

Effect of Iron Ore Pellet Size on its Properties and Microstructure

The properties of the pellets and their microstructure mainly depend on the raw material mix proportion, raw material chemical composition and the physicochemical conditions like the temperature and oxygen partial pressure within the induration machine. The pelletising plant products are in the size range of 8 to 16 mm. With increasing pellet size, the sintering intensity, thermo‐chemical conditions and formation of different phases vary across its cross section. The time required for varies reactions within the pellet is directly proportional to the pellet size. Because of differences in pellet size, the reduction and oxidation process takes place under different conditions resulting in different phases and microstructures. In this work, detailed studies were carried out on pellets of different size (8 to 16 mm) produced from a 4.2 Mtpa pellet plant for their physical, metallurgical and microstructural properties. It was observed that the pellets in the size range of +8 to ‐12 mm showed good strength and lower RDI. It was observed that the amount of hematite, magnetite, porosity, pore density, pore size and slag phase play a significant role on pellet strength and RDI.     

竖炉球团配加巴西精粉的试验研究

为提高球团矿品位，改善冶金性能，进行了竖炉球团配加巴西精粉的试验研究。通过成球及焙烧试验，提出了适宜的巴西精粉配比和合理的焙烧制度，并对成品球团矿冶金性能进行了检测，同时对试验结果进行了分析和阐释。     

球团矿化学成分控制现状及展望

 综述了近年来国内外高炉球团矿使用比例的现状,分析了球团矿化学成分控制以及不同化学成分对球团矿冶金性能的影响。分析表明,多数国内钢铁企业球团矿TFe的质量分数较低,SiO₂质量分数较高且差异较大。不同企业球团矿Al₂O₃和FeO的质量分数不同。应控制球团矿中SiO₂、Al₂O₃和FeO的质量分数。随着CaO和MgO质量分数的提高,球团矿抗压强度均降低。适宜质量分数的CaO有利于改善球团矿的还原膨胀性能。随着MgO质量分数的提高,球团矿的还原膨胀性和软熔滴落性能均变好。高炉炉料结构采用低MgO烧结矿、酸性球团矿和镁质球团相结合,可以充分发挥球团矿的冶炼优势,实现球团矿入炉比例的提高。MgO和CaO在球团矿焙烧过程中的作用机理,以及如何控制镁质球团中的液相含量以提高球团矿的抗压强度等需要进一步深入研究。     

Investigation of factors affecting pellet strength in straight grate induration machine

Abstract

During induration in a straight grate machine, the green pellets pass through four different thermal treatments, namely drying, preheating, heating and cooling. The pellet bed is fired with downdraught firing leading to thermal gradients through the bed. Corex sludge, which is used as fuel in the pellet mix, supplies the necessary energy for uniform heating of the pellet. The physicochemical conditions, e.g. the temperature and oxygen partial pressure mainly depend on the amount of fuel incorporated in the pellet mix. As a result the percentage and the distribution of various phases in the pellets vary, leading to deviation in quality. To study the distribution of phases and their impact on cold crushing strength at different carbon levels (1·20 and 1·35%), pellets from different layers of the induration bed in an industrial straight grate were characterised. It was observed that the strength of the pellets varied from 142 to 268 kg/pellet and 128 to 245 kg/pellet across bed, with carbon 1·20 and 1·35% respectively. It was found that middle layer pellets had higher strength compared to top and bottom layers. It was observed that amount of hematite, magnetite, porosity and the pore size plays a significant role on the pellet strength. Pellets with 1·20% carbon showed better physical and microstructural properties across the pellet bed compared to pellets with 1·35% carbon.     

邯钢烧结厂的技术进步

在实验室和工业试验的基础上，小球烧结技术成功地应用于生产。通过停开小烧结机，建设400m^2烧结机实现烧结装备的大型化。烧结生产率以及烧结矿的品位和冶金性能都得到了很大的提高。     

济钢球团配加炼钢污泥工业试验

为减少环境污染,合理利用炼钢污泥降低球团生产成本,在济钢10m^2球团竖炉上进行了球团配加炼钢污泥工业试验。结果表明,球团配加炼钢污泥,可以改善生球性能,提高球团矿的质量,降低球团矿的生产成本。