中文摘要：

针对某种低品位复杂难选铁矿石,研究原矿压块—直接还原—磨矿磁选工艺的影响因素和机理。将矿石破碎到粒径小于4 mm后,加入一定量黏结剂C和内配煤压块,通过对压块、直接还原焙烧和磨矿磁选条件进行试验确定最佳工艺条件,采用X线衍射（XRD）和扫描电子显微镜（SEM）对原矿在不同内配煤用量下压块后直接还原反应机理进行研究。研究结果表明：在原矿直接还原反应中,不仅包括铁氧化物向金属铁的还原,而且存在低价铁氧化物与原矿中脉石之间的反应,生成了铁橄榄石和铁尖晶石。提高内配煤用量,有利于铁氧化物和铁橄榄石等的还原。内配煤用量较高时焙烧块中生成的金属铁晶粒出现明显地连接和长大,与脉石矿物边缘界限明显,从而其回收率较用量低时有明显升高。得到铁品位为90.05%,回收率91.26%的直接还原铁产品。

英文摘要：

The mechanism and factors affecting the direct reduction roasting of refractory iron ore briquettes were investigated. Raw ore crashed to less than 4 mm was mixed with certain dosage of binder C and reductant coal for briquetting. A series of tests were carried out and the optimum condition was determined. The briquettes with different coal dosages after reduction reaction were studied by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results show that there is not only the reduction of ferric iron to ferrous or metallic iron, but also the reaction of wustite with gangue in the ore which formed fayalite and spinel. Therefore, increasing the coal dosage in the briquettes improves the reduction of iron oxide and fayalite to metallic iron. The obvious connection and growth of metallic iron crystals appear in the briquettes with more coal dosage, the boundary between metallic iron crystals and grey slag is clear in the briquettes, thus, the iron recovery rate of direct reduction iron is higher than that obtained with less coal dosage. The direct reduction iron （DRI） with 90.05% iron grade and 91.26% recovery rate was obtained.