Separate recycling of iron and aluminum from iron-rich red mud by coal gangue reduction to realize solid waste utilization

Abstract

Iron-rich red mud is a typical solid waste in the aluminum industry. And coal gangue is generated during the coal selection process. The efficient treatment of these two kinds of large reserves of solid waste has important resource value and environmental value. In this study, the co-roasting of iron-rich red mud with coal gangue for iron and aluminum recycling was explored. The optimum conditions were 850 °C, 30 min, 30 % coal gangue, −37 μm accounts for 85.88 %, and magnetic intensity of 132 × 10³A/m. Then the iron recovery, TFe grade, iron yield, Al₂O₃ content of iron concentrate were 70.14 %, 59.77 %, 49.14 %, and 8.26 %, separately. the Al₂O₃ content and recovery rate in Al-containing products were 16.90 %, and 64.35 %, separately. Based on the analysis of materials, hematite was transformed to magnetite, and diaspore was transformed into Al₂O₃ through co-roasting. Its saturation magnetization strength increased from nearly 0 A·m²·kg⁻¹ to 7.23 A·m²·kg⁻¹. Meanwhile, the sample changed from compact to porous honeycomb structure, and the newly formed small magnetite particles were densely distributed on the surface. Therefore, the co-roasting achieved tailings-free resource utilization of two types of solid waste, as well as co-roasting to effectively separate iron and aluminum from red mud and coal gangue.