Red mud is a type of solid waste derived from the alumina extraction process. It can be considered as a secondary resource for recovering iron values because of its high content of ferric oxide. In this study, an innovative technology called suspension magnetization roasting (SMR) was applied to treat red mud to recycle iron. Based on the lab-scale experimental basis, we adopted the single factor method to perform the semi-industrial scale experiments. Under the optimum conditions, the recovery and grade of iron in the iron concentrate were 95.22 % and 55.54 %, respectively. Chemical phase analysis, vibrating sample magnetometer, and XRD combined with Mössbauer spectroscopy were employed to assess the characteristics of red mud and roasted products. Occupancy of Fe content in magnetite was raised to 89.91 % in SMR products from 0.75 % in the red mud; saturation magnetization was enhanced from 0.40 A·m2/kg to 32.44 A·m2/kg; and the hematite and goethite phase were transformed into Fe3O4 (A), Fe3O4 (B) and γ-Fe2O3 phase. In addition, transmission electron microscopy analysis revealed that both magnetite and maghemite were found in the roasted product. This study demonstrates that SMR is a promising technology for the recovery of iron from red mud.

中文翻译：

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悬浮磁化焙烧技术从赤泥中分离铁矿物的半工业实验。

赤泥是一种来自氧化铝提取过程的固体废物。由于其高含量的三氧化二铁，可以认为是回收铁价的辅助资源。在这项研究中，一种称为悬浮磁化焙烧（SMR）的创新技术被用于处理赤泥以回收铁。在实验室规模的实验基础上，我们采用单因素方法进行了半工业规模的实验。在最佳条件下，铁精矿中铁的回收率和品位分别为95.22％和55.54％。化学相分析，振动样品磁力计和XRD与Mössbauer光谱法结合使用来评估赤泥和焙烤产品的特性。SMR产品中磁铁矿中Fe的含量从0提高到89.91％。75％的赤泥；饱和磁化强度从0.40 A·m2 / kg提高到32.44 A·m2 / kg；赤铁矿和针铁矿相转变成Fe3O4（A），Fe3O4（B）和γ-Fe2O3相。另外，透射电子显微镜分析表明在焙烤产品中发现了磁铁矿和磁铁矿。这项研究表明，SMR是从赤泥中回收铁的有前途的技术。