LEACHING OF URANIUM AND THORIUM FROM RED MUD USING SEQUENTIAL EXTRACTION METHODS

Red mud can be generated during production of alumina from bauxite using Bayer process or sintering alumina process. The specific chemical and mineral composition of different red mud is highly dependent on the nature of the parent bauxite ore and the processing parameters. The disposal of red mud poses an issue of great importance with significant environmental concerns. As major natural radioactive elements, uranium and thorium restrict the use of red mud as building materials or additives, and threat the environment because of their radio-toxicity and chemical toxicity. In view of the toxic nature of uranium and thorium the disposal of red mud needs prior evaluation. The concentrations and distributions of U and Th in Bayer red mud (BRM) and red mud from sintering alumina process (RMS) from Guizhou, China, were studied using sequential extraction methods. The total leachability of U in BRM and RMS was about 80% and 50%, respectively, while the leachability of Th during sequential extraction in BRM (about 15%) and RMS (about 22%) was much lower.