复杂难选铁矿石悬浮磁化焙烧预处理与高效分选基础研究

Suspended magnetization roasting pretreatment is one of the most promising preprocessing technology of refractory iron ore, proven reserves of which is more than 20 billion tons in China. Therefore, it is extremely essential for investigating their basic scientific issues on the process in theory and fact. An innovative idea of “Preoxidation–autothermal reduction–Reoxidation” (PARR) in suspended magnetization Roasting was proposed to pretreat the refractory iron ores. During the PARR process, the main Fe-bearing minerals, e.g. hematite, siderite, limonite, etc., in the iron ore as heat carrier, are oxidized into hematite by heating , which are afterwards reduced magnetite(Fe3O4) using the stored heat of the ore particles in a suspended state, and then the reduced magnetite is reoxidized to ferromagnetic γ-Fe2O3 in the controllable cooling process to recovery waste heat. by means of investigating the mineralogical properties of samples from different roasting stage, analyzing the thermodynamics and dynamics of the roasting process, simulating the gas-particle two-phase flow and its heat transfer, and optimizing the separation technology for roasting product, the multistage reaction mechanism and characteristics of particle flow and heat transfer for inhomogeneous ore particles under the multi-factor influence will be studied, and phase transformation will be controlled accurately, and efficient separation for roasting product will be conducted controllably. The theoretical system of suspended magnetization roasting pretreatment and efficient separation for refractory iron ore will be improved to solve basic theoretical problem which could restrict process control and industrialization of suspended magnetization roasting pretreatment and efficient separation for roasting product, which provides theoretical support for efficient utilization of refractory iron ore.

我国复杂难选铁矿资源丰富，探明储量超200亿吨，采用悬浮磁化焙烧预处理技术可实现高效利用，研究该过程中的基础性科学问题具有重要的理论与实际意义。本项目首次提出“预氧化-蓄热还原-再氧化”悬浮磁化焙烧新理念，即以铁矿石本身作为热载体，在加热过程中使多种铁矿物氧化为赤铁矿，再利用矿石本身蓄热在悬浮态下还原为磁铁矿，控制冷却过程使磁铁矿部分再氧化为强磁性γ-Fe2O3以回收潜热。通过研究悬浮磁化焙烧预处理过程中工艺矿物学特性差异、多段反应热力学计算及动力学分析、气固两相流动及传热数值模拟、焙烧产品分选过程优化，揭示悬浮磁化焙烧预处理过程的多段反应机理、多因素耦合影响下非均质矿石颗粒流动和传热规律，实现物相转化精准控制，获得焙烧产品高效分选调控机制，建立悬浮磁化焙烧与高效分选理论体系，解决制约悬浮磁化焙烧过程控制、工程放大和焙烧产品高效分选的基础性科学问题，为复杂难选铁矿石的高效利用奠定理论基础。

我国铁矿资源储量丰富，但以低品位矿石为主，常规选矿方法难以获得较好的技术经济指标。本项目以微细粒赤铁矿、菱铁矿为研究对象，提出了“预氧化-蓄热还原-再氧化”悬浮磁化焙烧新技术，围绕悬浮磁化焙烧过程中矿相转化、气固两相流动及传热特性、焙烧产品高效分选等关键科学问题开展了系统的基础研究工作，并取得了重大突破。.发现了赤铁矿、菱铁矿、褐铁矿化学反应特性差异是常规磁化焙烧效果差的本质原因，创建了“铁物相分段精准调控”新理论，开发了以铁矿石颗粒为热载体，加热与还原异步分腔、冷却过程再氧化多段悬浮磁化焙烧新技术；揭示了人工磁铁矿冷却过程向磁赤铁矿转化机制，创造性提出适时风冷物相调控强化分选同步回收潜热新方法；探明了非均质矿石颗粒及气体的流动特性差异，创造性研发了兼具还原和密封双重功能的U型还原反应器，突破了铁矿石细粒全粒级流态化高效还原的技术壁垒，解决了加热与还原同步关联的“卡脖子”技术难题，开发了悬浮磁化焙烧成套技术装备，并在赞比亚建成了60万吨/年示范工程，预计盘活复杂难选铁矿资源200亿吨以上。.项目建立了物相精准调控强化分选的难选铁矿石悬浮磁化焙烧理论体系，阐明了流态化作用下气固两相流动行为及传热特性，破解了国际公认的微细粒赤铁矿、菱铁矿等典型难选铁矿石开发利用难题。研究成果获辽宁省技术发明一等奖1项，出版国家出版基金资助专著1部，发表学术论文64篇，其中SCI、EI收录50篇；授权国际发明专利1项、中国发明专利24项，累计实施科技成果转化270万元；培养国家级青年人才3人、中国科协青年人才1人、省级青年人才4人，培养研究生18人，参加国内外学术会议60余人次。