细粒铁物料闪速磁化焙烧前后的性质表征

对-0.30 mm酒钢富含镜铁矿、褐铁矿和镁(锰)菱铁矿的难选铁粉料进行了闪速磁化焙烧研究, 在弱还原气氛和740～800 ℃下, 通过闪速磁化焙烧处理, 获得了铁品位为55.67%～55.21%、铁作业回收率为81.66%～86.57%的弱磁选铁精矿。闪速焙烧前后物料的X射线衍射、磁性能测定和穆斯堡尔谱分析表明: 弱磁性细粒铁矿物的相均转变为龟裂较为发育的人造磁铁矿, 化学成分为Fe₃O₄, 其比饱和磁矩较焙烧前增加33～42倍不等, 计算表明闪速磁化焙烧的速度较常规的磁化焙烧时间快几十至数百倍; 在闪速磁化焙烧过程中, 菱铁矿的磁化转变过程主要由化学反应速度控制, 而镜铁矿的磁化转变过程受扩散控制影响, 部分未转化完全。

Characterization and Properties of Fine Iron Minerals before and after Flash Magnetic Roasting

Flash magnetic roasting(FMR) technique was introduced to treat a -0.30 mm refractory iron powder containing specularite, limonite and Mg-Mn siderite from JISCO. After a FMR process at 740~800 ℃ in a slightly reducing atmosphere, an iron concentrate with a Fe grade and recovery of 55.67%～55.21% and 81.66%～86.57%, respectively, can be obtained after a further low intensity magnetic separation. Characterization of the powder before and after FMR with X-ray diffraction, magnetic detection and Mssbauer spectra indicate that, the specific saturation magnetic moment can be increased by 33～42 times amid FMR, and the weakly magnetic iron minerals can be converted into artificial magnetite with main chemical component of  Fe₃O₄ with well-developed cracking. According to the calculation, the roasting speed with FMR is about dozens to several hundred times faster than that with ordinary magnetic roasting. In the process of FMR, magnetization transformation of Mg-Mn siderite is mainly controlled by chemical reaction, while that of specularite is determined mainly by diffusion, part of which has not been magnetized.