【作者】 张贺雷；

【导师】 邱冠周； 姜涛；

【作者基本信息】 中南大学 ， 冶金工程， 2014， 博士

【摘要】 摘要：随着钢铁工业的迅速发展,我国铁矿石自给能力严重不足,进口铁矿石价格不断攀升,国内钢铁企业的炼铁成本也随之上涨。高效、大配比使用价格相对较低的非传统铁矿资源(如镜铁矿)及二次资源(如含铁尘等)作为炼铁原料,对于降低炼铁成本和企业节能减排都具有重要的现实意义,但由于上述原料大多存在难成球、难焙烧等原因,使得现有造块工艺中无法大量使用。铁矿粉复合造块工艺是近期发展起来的一种新的造块技术,在难处理复杂矿、细粒铁矿及含铁二次资源等方面具有显著优势。随着宝钢新建高炉投产及原有高炉大修扩容,烧结产能已远远不能满足炼铁生产要求。在宝钢当前炼铁原料结构和烧结技术条件下,研究采用复合造块新工艺来提高烧结矿生产能力,解决宝钢炼铁原料短缺的问题、改善烧结矿产质量、实现烧结节能降耗、降低炼铁成本具有重要的意义。本文以镜铁矿和宝钢自产含铁粉尘为研究对象,在研究镜铁矿与含铁粉尘的成球性能、焙烧固结性能,以及配加镜铁矿粉和(或)含铁粉尘对宝钢生产现场用匀矿烧结性能影响的基础上,考查了采用复合造块工艺实现高配比镜铁矿和含铁粉尘造块的可行性及工艺条件,并通过料层透气性试验及料层气体力学分析,研究球团料及基体料对复合造块料层透气性的影响规律,揭示了复合造块工艺可显著提高产量的机理；考查了镜铁矿球团在复合造块过程中的固结和成矿行为,揭示复合造块工艺改善产品质量的机理。本研究的创新点和获得的主要结论如下(1)研究镜铁矿与含铁粉尘的造块性能,查明了镜铁矿粉和含铁粉尘的难造块的原因。镜铁矿粉表面光滑、结构致密、成球性能较差,所需焙烧温度较高(需要达到1280℃以上)。用于球团生产时,需要经过60min-90min湿式球磨和3次高压辊磨预处理后所制备的生球质量指标方能满足要求。配入烧结混合料时,与单一匀矿烧结结果相比,在配加19.6%的镜铁矿粉后进行烧结垂直烧结速度降低了5.27mm/min,成品率减小了8.84%,利用系数降低了0.454t·m-2·h-1;同样,在匀矿中直接配加10%含铁粉尘进行烧结,与采用单一匀矿烧结获得的试验指标相比,垂直烧结速度下降了222mm/min,转鼓强度降低了1.79%。(2)研究复合造块工艺料层气体运动规律及料层透气性变化规律,探明了复合造块工艺显著提高造块产量的机理。复合造块料层中由于在基体料中加入球团,在两者粒度匹配的条件下,可提高料层透气性透气性,在烧结料细粒含量少于50%的情况下,加入30%～40%的球团,料层透气性可以提高20%～30%。(3)研究了镜铁矿球团在复合造块过程中的固结和成矿行为,揭示了复合造块工艺改善造块产品质量的机制。复合造块产品具有比常规烧结矿更好的显微结构强度,该产品由酸性球团矿与高碱度烧结矿紧密镶嵌构成,高温冶金性能研究表明,制备的成品复合烧结矿可作为一种优质的炼铁炉料。对于匀矿基体料,由于其具有超高碱度,针状铁酸钙(SFCA)可大量生成,结晶互连后具有优良的强度；对于镜铁矿球团料,在高温制度下诱导原生Fe2O3发生物相转变,分解、再氧化后生成次生Fe2O3,次生Fe2O3由于具备更高活性,进而可促进球团料的固结。造块产品中的酸性球团料镶嵌在高碱度基体料中,两者依靠烧结过程中高碱度基体料产生的液相紧密相连,形成复合造块产品的整体强度,其主要矿物有铁酸钙,还含有部分赤铁矿和少量橄榄石等。(4)开发了高配比镜铁矿和含铁粉尘的复合造块工艺。与常规烧结工艺相比,采用复合造块工艺时镜铁矿的配加量可由10%提高到40%以上,粉尘配比可提高到10%以上,同时料层高度可由常规的700mm提高到820mm以上,有效地实现了烧结生产的增产、节能,目前,该工艺已在宝钢完成工业化可行性研究,证实了该工艺的工业化实施是可行的。更多还原

【Abstract】 Abstract:With the rapid development of the steel industry of China as well as the increasing price of imported iron ore, the iron-making cost of domestic steel companies has also increased due to a serious shortage of self-sufficiency of domestic iron ore. Efficient utilization of a large proportion of iron ore with relatively low price, such as non-traditional resources (e.g. Specularite ore) and secondary sources (e.g. iron-bearing dust), is of great significance for the reduction of iron-making cost as well as energy conservation and emission reduction. However, the existing processes are not capable of utilizing specularite ore and iron-bearing dust in a large scale, due to their properties of low ballability and refractory performance. Composite Agglomeration Process (CAP) is a brand-new process with significant advantages for the agglomeration of iron-bearing materials in terms of refractory iron ore, fine-grained iron ore and secondary resources currently.The sintering capacity of Baosteel has not already met the requirement of feedstock for blast furnace with the expansion of existing BF together with the construction of new BF. Thus, under the current conditions of raw materials source and sintering technology, the research on the application of Composite Agglomeration Process (CAP) to increase the production capacity and improve the quality of sinter is of great significance, for the aims of energy conservation and cost reduction.In this paper, specularite ore and iron-bearing dust derived from Baosteel were used as the main raw material, and the properties in terms of ballability, roasting consolidation performance, and their effects on the sintering performance of ordinary iron ore were investigated. Feasibility and optimal process parameters of CAP for the utilization of high-ratio of specularite ore and iron-bearing dust were examined. Subsequently, effects of pellet and matrix material on the permeability of sintering bed were investigated to interpret its function of increasing productivity, via gas mechanics analysis of sinter bed. Moreover, consolidation and mineralization behaviors of specularite ore were studied, in order to reveal the mechanism of sinter quality improvement by using CAP. The innovations of this study and the main conclusions obtained are as follows:(1) Agglomeration performances of specularite ore and iron-bearing dust were examined and reasons for difficulty in agglomeration were explained. Specularite ore is with smooth surface, compact structure and poor ballability, as well as a higher roasting temperature requirement (more than1280℃). As for the pellet production, specularite ore needs pretreatment of60～90min wet ball grinding and three times high-pressure roller grinding, so that the quality indicators of green balls can only meet the basic requirements. The sintering indexes of ordinary iron ore was deteriorated with addition of19.6%specularite ore, and the vertical sintering velocity decreased by5.27mm/min, yield decreased by8.84%, and productivity decreased by0.454t·m-2·h-1. Likewise, with addition of10%iron-bearing dust, vertical sintering velocity dropped by2.22mm/min, and the drum strength decreased by1.79%.(2) The permeability changes of sintering bed were investigated and the mechanism of yield improvement of CAP was proposed. The permeability of the sinter bed increased by20%-30%when the matrix material was mixed with30%～40%pellet material.(3) Consolidation and mineralization behaviors of specularite ore during CAP were studied and the enhancement mechanism of sinter quality revealed. The CAP product possesses better microstructure strength than conventional sinter, which is composed of acidic pellets and high basicity sinter. High-temperature metallurgical properties of the CAP product show that it can be used as a qualified feed for iron-making. Regarding with the matrix material of ordinary iron ore, needle-like calcium ferrite (SFCA) can generate a lot after crystallization resulting in an excellent strength because of its ultra-high alkalinity; as for the pellet material of specularite ore, the consolidation of pellet was promoted due to the formation of secondary Fe2O3with high activity sourced from the decomposition and re-oxidation of the original Fe2O3. In the CAP product, acidic pellets are embedded in the high alkalinity matrix material, both of them are bonded by the liquid phase generated from the high alkalinity matrix material during sintering, and it is mainly constituted of calcium ferrite and hematite, and also a small amount of olivine.(4) CAP for utilization of a high ratio specularite ore and iron-bearing dust was developed. Compared with conventional sintering process, the dosage of specularite ore can be increased from10%to40%, and the iron-bearing dust ratio can be increased to over10%, meanwhile the height of sinter bed could be increased to from700mm to820mm or above. CAP has advantages of increasing production yield and reducing energy consumption, and a feasibility study of this process has been performed in Baosteel and proves that the implement of this process for industrialization is practicable.更多还原