Fe-Si Alloy Preparation and Alumina Extraction from Red Mud and Silica Fume via Vacuum Carbothermal Reduction

With the increasing awareness of environmental protection, the disposal of solid waste such as red mud (RM) and silica fume (SF) has attracted widespread attention. In this study, a novel method by recycling RM and SF simultaneously was proposed for preparing Fe-Si alloy and extracting alumina. The process is mainly composed of vacuum carbothermal reduction and magnetic separation. The results show that Fe-Si alloy was successfully synthesized during the vacuum carbothermal reduction and it was effectively separated during the magnetic separation. Additionally, after the magnetic separation, the non-magnetic portion mainly contains alumina and it can be a potential raw material to produce alumina by the Bayer process. This process could recycle RM and SF simultaneously, and almost no waste residue was generated. Therefore, it provided a clean and sustainable route for synergistic recycling of RM and SF.