Efficient extraction and recovery techniques of valuable metals and alumina with high added value from red mud: A comprehensive review

• The physical properties, chemical composition of red mud and its harm to the environment were systematically analyzed. • A systematic comparison and analysis were conducted on different iron extraction processes from red mud and their impacts on the environment. • The process of titanium extraction from red mud was summarized, and its mechanism was discussed. • Summarized the influencing factors of the alumina recovery process from red mud and compared its impact on the environment. Red mud (RM) is a byproduct of alumina refining and has a high content of alumina and valuable metals. However, the accumulation and idling of red mud resources have caused serious waste of resources, environmental pollution and public safety hazards. Therefore, there is an urgent need to develop green comprehensive utilization technologies for red mud resources in order to achieve harmless and high-value treatment. In this work, the extraction and separation process of valuable metals in red mud is systematically introduced and summarized, and the recovery mechanism and development status of valuable metals Fe, Ti and high value-added Al 2 O 3 are emphasized. In addition, based on the recovery capacity, energy consumption and environmental pollution of valuable metal and alumina recycling processes, the advantages, disadvantages and environmental implication of various recycling processes are also summarized and compared in detail, aiming to provide theoretical guidance for the harmless and high-value utilization of red mud.