High Iron Diasporic Bauxite Processing Study

A new approach was applied to processing high iron diasporic bauxite which involves firstly pre-processing at low temperature with high αK liquor and then digesting at high temperature with recycled mother liquor. The pre-processing and digestion conditions which affect A/S and N/S of the red mud generated were explored. The bauxite was pre-processed at conditions of 150 °C, NK = 260 g/L and 9% lime addition, before being digested at 260 °C for 60 minutes, resulting in an A/S in the red mud produced of 0.74, with an N/S of 0.12. The pre-processed bauxite and the red mud were analyzed by XRF, XRD and SEM-EDS. The main Silica mineral of both the pre-processed bauxite and the red mud was a hydrogarnet where Al was substituted by Fe and Ti. It was concluded that this hydrogarnet is formed in pre-processing, that it is stable through digestion, resulted in improved diaspore digestion, and is the reason why A/S and N/S in the red mud generated is greatly reduced under the conditions of pre-processing and digestion.