铁矿石碳热还原过程中铅锌脱除及含铁物相的演变规律

针对含铅0.39%、含锌0.30%的铁矿，采用碳热还原脱除铅锌杂质，利用X射线衍射、扫描电子显微镜及能谱分析等检测手段考察了铁矿还原焙烧过程的反应行为及物相演变规律。结果表明，该铁矿中铅主要以氧化铅和铅铁矾形式存在，锌主要以氧化锌形式存在; 升高焙烧温度及延长焙烧时间均有利于铅锌脱除; 在1 200 ℃下焙烧60 min时，铁矿中铅和锌脱除率均在90%以上。含铅锌铁矿在碳热还原焙烧过程中会生成中间产物铁橄榄石，并最终转变为金属铁和游离的氧化硅固溶体。还原焙烧产物经磁场强度80 kA/m弱磁选可获得铁品位91.91%和铁回收率84.78%的铁精矿，且铁精矿中铅和锌含量分别为0.01%和0.03%，可作为电炉炼钢原料使用。

Removal of Lead and Zinc Impurities and Phase Evolution Laws of Ferriferous Minerals Amidst Iron Ore Carbothermal Reduction

By adopting the carbothermal reduction approach, the lead and zinc impurities in an iron ore containing 0.39% Pb and 0.30% Zn were removed, and the reaction behavior and phase evolution of iron ore during reduction roasting were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results show that lead oxide and plumbojarosite are the dominant lead minerals in the iron ore, while zinc exists in the form of zinc oxide. Both raising roasting temperature and prolonging roasting time can improve the removal rates of the Pb and Zn, showing the removal rates all over 90% after 60 min-roasting at 1 200 ℃. During the reduction roasting of iron ores, an intermediate product of fayalite can be derived and ultimately converted into metallic iron and free cristobalite solid solution. After reduction roasting process, the product is subjected to a low intensity magnetic separation at a magnetic field strength of 80 kA/m, yielding 84.78% recovery into a concentrate grade of 91.91% Fe, with the content of Pb and Zn in the concentrate reduced respectively to 0.01% and 0.03%, which can be used for electric furnace steelmaking.