高铁煤泥作还原剂直接还原褐铁矿研究

摘要

The effects of dosage of reducing agent, reduction temperature and time on direct reduction of limonite with iron-rich coal slime were studied by comparison with anthracite. The phase and morphologies of limonite ore and its coal slime pellets at different reducing temperature were investigated by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that the metallized pellets with metallization ratio at 86.4% was obtained after 20 min direct-reduction at 1200 ℃ by adding coal slime at the amount of 25%. It is found that in the direct reduction process, the ferric iron was reduced to ferrous or metallic iron, and the intermediate products reacted with gangue, forming fayalite and spinel, which were reduced to metallic iron again. And the metallic iron in the product exists predominately in a granular form, and clear phase boundaries can be observed between slag and metallic iron. No iron oxide was detected in the slag phase under optimal conditions and iron oxides in the coal slime were reduced to metallic iron during the reaction, which had increased the metallization rate of pellet to some extent.%以高铁煤泥为新型还原剂,直接还原褐铁矿.通过与无烟煤对比,探索了还原剂用量、还原温度和还原时间对褐铁矿直接还原的影响.采用X射线衍射(XRD)和扫描电镜(SEM)等手段,研究了褐铁矿原矿及其煤泥球团在不同温度下的物相和形貌.结果表明:煤泥用量25%,经1200℃ 直接还原20 min后,可得到金属化率86.4%的金属化球团.在直接还原反应中,不仅包括铁氧化物向金属铁的还原,而且存在中间产物与脉石反应生成铁橄榄石和铁尖晶石再还原生成金属铁,金属铁在产物中主要以金属铁颗粒的形式存在,渣铁相界面分明,最佳状况下渣相中检测不到铁氧化物,煤泥中的铁氧化物随反应的进行被还原为金属铁,一定程度上提高了球团金属化率.