Abstract: Magnetic roasting via a fluidized bed reactor was carried out for the beneficiation of a Yunnan oolitic iron ore. The magnetic roasting was performed at 550~800℃ for 2~20 min under mixed CO and N2 atmosphere. The results show that direct magnetic roasting followed by magnetic separation can only upgrade the concentrate to the total iron content of about 55% with a Fe recovery rate less than 70%, while with a pre-calcination process at 800℃ for 60 min to remove the crystalline water of iron ore prior to the magnetic roasting, a iron ore concentrate with total iron content of 60.18% at a recovery rate of 85.91% can be successfully obtained. The pretreated ore formed lots of pores by the pre-calcination process. These pores provided gas-diffusion channels to facilitate the reduction within the particles, which accelerated the growth of Fe3O4. Therefore, the Fe grade and recovery rate of iron ore concentrate could be improved.

Key words: fluidized bed, oolitic hematite and limonite ore, magnetic roasting

摘要： 采用流化床反应器作为磁化焙烧装置，以高纯N2和CO混合气体作为还原气体，考察了550~800℃下，云南某地区的鲕状赤褐铁矿磁化焙烧-磁选的影响因素. 结果表明，未经过预处理的矿粉采用磁化焙烧-磁选分离，精矿中铁品位可提高至约55%，铁回收率<70%；经过预处理的矿粉，精矿中铁品位可提高至60.18%，铁回收率达85.91%. 预处理矿粉形成了多孔疏松结构，使还原气体易进入铁矿颗粒内部，有利于Fe3O4生成，提高了磁选指标.

关键词: 流化床, 鲕状赤褐铁矿, 磁化焙烧