ABSTRACT

Oolitic hematite, as a complex and refractory iron ore resource, can be efficiently utilized by magnetic roasting. In this study, to ascertain the mechanism of microwave fluidization roasting technology (MFR) for the utilization of oolitic hematite, the influence of MFR on mineral magnetism, ore microstructure, mineral phase and kinetics was further explored and clarified. The results show that under the optimized conditions of the roasting temperature 650°C for 5 min, CO concentration 30%, and ore fineness with −74 μm accounting for 90%, the saturation magnetization and saturation susceptibility of the roasted product reached the maximum respectively. Microstructure analysis shows that microcracks were generated between iron minerals and gangue minerals and gradually extended to the core of the oolitic structure with a prolongation in pretreatment time, which was particularly propitious to upgrade the iron minerals in the subsequent grinding and magnetic separation process. The isothermal kinetics shows that the apparent activation energy and pre-exponential factor of kinetic parameters in MFR process decreased gradually with a decrease in ore particle size, and the mechanism function for ore with the particle of −0.15 mm was in accordance with the one-dimensional diffusion model k = 3.805exp(−24075/RT).

摘要

鲕粒赤铁矿作为一种复杂难选的铁矿石资源，可通过磁焙烧得到有效利用。本研究为明确微波流化焙烧技术（MFR）利用鲕状赤铁矿的机理，进一步探讨和阐明了MFR对矿物磁性、矿石微观结构、矿物相和动力学的影响。结果表明，在焙烧温度650℃、焙烧5 min、CO浓度30%、矿石细度-74 μm占90%的优化条件下，焙烧产品的饱和磁化强度和饱和磁化率分别达到最大值。 . 显微组织分析表明，随着预处理时间的延长，铁矿物与脉石矿物之间产生微裂纹，并逐渐延伸至鲕粒结构核心，特别有利于铁矿物在后续的研磨和磁选过程中进行升级改造。等温动力学表明，MFR过程中的表观活化能和动力学参数的指前因子随着矿石粒度的减小而逐渐减小，-0.15 mm粒度矿石的机理函数符合一-维度扩散模型k = 3.805exp(-24075/ RT )。