褐煤热解提质菱铁矿直接还原的耦合效应与多联产应用基础研究

It is significant for sustainable development of friendly environment, resource conservation and efficient energy use that the research of synchronous utilization of siderite direct reduction and lignite pyrolysis. In view of easily hot chalking of siderite, easy to form ring of coal based direct reduction in rotary kiln and difficult to use lignite resource, the coupling effects between lignite pyrolysis and siderite ore direct reduction are researched in order to improve the reaction efficiency, and the polygeneration technology for direct reduction of siderite - lignite is developing. The main contents are as following: 1)to research movement rule of siderite / lignite particle group, reveal a mechanism of protecting particle strength under hierarchical motion mode, and describe the mechanism of prevent ring formation in direct reduction kiln. 2) to study the coupling effect of the direct reduction of siderite with lignite pyrolysis and control mechanism, analyze the pyrolysis behavior of lignite under internal heating by DRI - Char solid heat carrier ,establish the coupling reaction system of direct reduction with siderite and lignite , develope the prototypes of polygeneration technology for direct reduction of siderite- lignite to produce direct reduction iron - char - gas; 3) to characterize the physical and chemical properties of semi-coke, study sintering behavior of semi-coke to partially replace metallurgical coke.Through a deep understanding of interaction mechanism between pyrolysis upgrade of lignite and direct reduction of siderite to achieve efficient use of refractory siderite and low rank coal in one step process, it has important scientific significance for utilization of low quality iron / coal resources.

研究菱铁矿直接还原与褐煤热解提质的同步利用，对环境友好、资源节约和能源高效利用的可持续发展意义重大。针对菱铁矿受热易粉化，煤基回转窑直接还原易结圈及褐煤资源难利用的问题，研究褐煤热解与菱铁矿石直接还原的耦合效应，提高反应效率，开发褐煤热解提质菱铁矿直接还原一步法多联产技术。主要研究内容有：1）研究菱铁矿/褐煤颗粒群运动规律，揭示分层运动模式下颗粒强度保护机制，阐述预防回转窑直接还原结圈机理；2）研究菱铁矿直接还原与褐煤热解的耦合效应及控制机理，解析还原铁-半焦固体载热体内热式褐煤热解行为，建立菱铁矿-褐煤直接还原的耦合反应体系，开发菱铁矿-褐煤直接还原多联产还原铁-半焦-煤气的技术原型；3）表征半焦的理化性能，研究半焦部分取代冶金焦用于烧结的行为。通过深刻认识褐煤热解提质与菱铁矿直接还原的相互影响机制，同步实现难处理菱铁矿和低阶煤的高效利用,对低品质铁/煤资源的综合利用具有重要的科学意义。

清洁高效利用复杂难选铁矿石及低阶煤受到国内外冶金界和能源界的高度重视。本研究以典型难选的低品位菱铁矿和难利用的低阶煤为研究对象，开展了褐煤热解提质菱铁矿直接还原的耦合效应与多联产应用基础研究，揭示了低阶煤热解提质过程中菱铁矿的直接还原机理及菱铁矿分解还原对低阶煤热解气化的影响机制，阐明了菱铁矿还原与低阶煤提质的相互耦合机制，发现菱铁矿的分解和低阶煤的热解相互制约，而煤焦气化产生的CO参与铁氧化物的还原反应，铁氧化物对煤焦气化起促进作用；菱铁矿分解产生的CO2气体一定程度上参与煤焦的气化反应，提高煤焦气化的碳转化率，增加CO煤气产量，有利于铁、焦、气（电）一体化工艺的多联产。开发了菱铁矿煤基回转窑直接还原-低阶煤提质一体化多联产工艺，并与传统选矿工艺技术结合，同时制备优质直接还原铁粉和半焦产品，并且半焦成功应用于铁矿粉烧结。在回转窑还原温度1050℃，还原时间120min，C/Fe质量比2.50，脱硫剂用量6%，菱铁矿粒度5~25mm，神府煤粒度5~25mm，干式磁选0.15T，一段磨矿细度-0.074mm在50%左右，湿式磁选磁场强度0.08T，二段磨矿细度-0.074mm在90%左右，磁选场强0.043T的优化工艺条件下可获得铁品位91.04%的还原铁粉，铁总回收率81.33%；所得半焦产率73.67%，固定碳含量76.11%，当半焦粒度-5mm占100%，-3mm占60%时，可100%替代焦粉用于铁矿粉烧结，不仅可提高烧结矿产量和强度，改善烧结矿还原性，而且使烧结过程SOx和NOx的排放量分别减少了66%和25%。该工艺符合目前短流程炼钢的发展趋势，拓宽了菱铁矿资源的利用途径，增加我国直接还原铁的产量，并同时产出高附加值的半焦产品，展现出了良好的应用前景。共发表学术论文15篇，授权发明专利4项,研究成果对高效清洁利用低品位铁矿资源和低阶煤资源具有重大意义。