Techniques and Mineral Chemistry of High Silica Bauxite for the Bayer Process

  • A/Professor Haipeng Wang, WASM, Curtin University of Technology, Australia
  • A/Professor Don Ibana, WASM, Curtin University of Technology, Australia
  • Mr Jian Zhang, WASM, Curtin University of Technology, Australia
  • Mr Marc Steffens, WASM, Curtin University of Technology, Australia

    • In this review paper, the mineral chemistry involved in various techniques in processing high silica bauxite for alumina production is discussed. Currently high silica bauxites cannot be economically processed by the Bayer process due to high caustic losses from the "desilication" reactions. Caustic losses occur in processing high silica bauxite account for more than 20% of the alumina production costs. Minimising caustic losses and maximising alumna yield were attempted to reduce the cost for processing low-grade bauxite (high in reactive silica). This review paper summarizes the techniques developed for high silica bauxite treatment in Bayer process. These techniques can be categorized to (i) preventing silica content from entering the process, (ii) modifying the desilication process in order to reduce soda losses (iii) recovering caustic from Bayer residue.