Gradient-based separation of iron and aluminum from bauxite residue through a two-step phase reconstruction process

Recycling of iron and aluminum from iron-rich bauxite residue (IRBR) offers a promising way for its high-value utilization, which is challenging due to its complex mineral composition. In this work, a two-step phase reconstruction process was proposed to sequentially extract aluminum and iron from IRBR. The process involves alkaline roasting and low-temperature reductive roasting-magnetic separation. Under the optimized alkali roasting condition, aluminum minerals in IRBR were transformed to sodium aluminate, and 64.27 % of the alumina could be efficiently leached and separated into the liquid phase , and iron content was enriched to 45.12 % in the residue. Following low-temperature reductive roasting, hematite in the residue could be selectively converted into magnetite. The transformed product after magnetic separation achieved iron grade and recovery rate of 60.6 % and 96.8 %, respectively, which could be utilized as a premium-grade industrial magnetite concentrate. This work may offer a new route for comprehensive recovery of Al and Fe from IRBR.