Abstract: Magnetic reduction roasting and low intensity magnetic separation accompanied at different temperatures were carried out for the beneficiation of an oolitic iron ore from in the west of Hubei Province. The effects of magnetic roasting time on magnetic separation, phase transformation of iron minerals and composition of oolitic iron ore were investigated with microscopic observation and statistic data of roasted particles, combined with XRD analysis. The results indicate that the mineral particles containing iron are mainly composed of different oolitic concentric shells from 1 to 2 mm and closely enwrapped tiny particles at about 10 mm. An iron ore concentrate with total iron content of 56.34% at the recovery rate of 88.05% can be obtained by magnetic tube separation under the roasting conditions of 800℃ for 60 min and slight reduction atmosphere for separation. The effect of roasting time on magnetization roasting is obvious. The magnetic roasting of oolitic iron ore can be accomplished in iron phase transformation, but the configuration of oolitic particles has not changed. Magnetization transformation is mainly controlled by solid-state diffusion from surface to interior. The reduction degree increases with roasting time. The phase transformation of wustite FeO hardly appears in less than 30 min, and a little FeO exists after then. Fe2SiO4 is seldom confirmed experimentally. The minerals containing P and Si have changed to some extent in phase transformation in different periods of roasting time.

Key words: oolitic iron ore, magnetic roasting, roasting time, phase transformation, separation

摘要： 以鄂西某鲕状赤铁矿为研究对象，考察了焙烧时间对其磁化焙烧与磁选过程、相态转化及焙烧变化规律的影响. 结果表明，含铁鲕粒多数由赤铁矿内核与致密同心外壳及其中间夹带的脉石矿物构成；含铁(TFe) 49.02%的鲕状赤铁矿在800℃下磁化焙烧60 min后再用磁选管分选，获得含铁56.34%、铁回收率为88.05%的较好结果，焙烧时间对磁化焙烧影响显著. 磁化焙烧过程仅改变铁相，而鲕粒结构未变；磁化还原由表及里受扩散作用控制，还原程度随焙烧时间延长逐步增加. 800℃下焙烧时间小于30 min时，极少过还原生成FeO，之后则有少量FeO生成，较少形成Fe2SiO4；含磷与含硅矿物均有相变，但转变时间不同.

关键词: 鲕状赤铁矿, 磁化焙烧, 焙烧时间, 相变, 分离