Abstract: Low-temperature magnetization roasting can not only improve the magnetic separation performance of bauxite but also improve the dissolution performance of bauxite. It provides a solution for the industrial utilization of high-iron bauxite. In order to realize the efficient recovery of aluminum and iron elements in high-iron bauxite, the method of "low-temperature magnetic roasting-Bayer digestion-red mud magnetic separation" is adopted to treat high-iron bauxite. The effects of roasting temperature, H2 concentration, and H2 input time on the dissolution and magnetic separation performance of high-iron bauxite were investigated. The effect of roasting on the phase transformation and microstructure of bauxite was analyzed via XRD, SEM, and BET. The results showed that diaspore dehydrated and transformed into transition Al2O3 during roasting. Thermal cracking occured in minerals, the specific surface area increased, and the leaching activity of alumina increased. The relative dissolution rate of alumina could reach 97.65% when the calcination temperature was 530℃, the concentration of H2 was 20vol%, and the time of H2 was 5 min. Magnetization roasting transformed hematite into magnetite with strong magnetism. After the magnetic separation of roasted ore, the grade of iron concentrate was 33.51wt%, and the iron recovery rate was 60.32%. The dissolution process could remove the embedding relationship between aluminum and iron elements. After the magnetic separation of red mud from roasted ore, the grade of iron concentrate reached 62.05%, and the iron recovery rate was 86.36%. The magnetic separation performance of red mud was far better than that of calcined ore. "Low-temperature magnetic roasting-Bayer digestion-red mud magnetic separation" realized the efficient separation of iron and aluminum from diaspore-type high-iron bauxite. The technical goal of removing iron and extracting aluminum had been achieved. It provided the theoretical basis and technical support for the subsequent development and utilization of high-iron bauxite.

Key words: high-iron bauxite, diaspore, magnetizing roasting, dissolution performance, red mud, magnetic separation

摘要： 为实现高铁铝土矿铝铁元素的高效利用，采用“低温磁化焙烧-拜耳溶出-赤泥磁选”的方式处理高铁铝土矿，考察了焙烧温度、H2浓度及通入时间对高铁铝土矿溶出及磁选性能的影响。结果表明，焙烧过程中一水硬铝石脱水转变为过渡态Al2O3，矿物发生热破裂现象，比表面积增大，氧化铝溶出活性增加，在焙烧条件为焙烧温度530℃、H2浓度20vol%、H2通入时间5 min时，氧化铝相对溶出率可达97.65%。磁化焙烧过程中，针铁矿转变为赤铁矿，再由赤铁矿转变为磁铁矿，通过溶出解除了铝铁元素之间的嵌布关系，对焙烧矿的赤泥进行磁选，其铁精矿品位达62.05wt%，铁回收率为86.36%。

关键词: 高铁铝土矿, 一水硬铝石, 磁化焙烧, 溶出性能, 赤泥, 磁选