Application of Tricalcium Aluminate Instead of Lime for the Recovery of Aluminum in Middle-Low Grade Bauxite in Calcification-Carbonization Process

In the process of calcification-carbonization, the alkali and aluminum in the mid-low grade bauxite and red mud can be recovered. Aluminum is obtained in the form of low-concentration sodium aluminate solution which is comparatively difficult to reuse. In this paper, the low-concentration sodium aluminate solution was reused to prepare tricalcium aluminate and went back to the Calcification-Carbonization process instead of lime. When processing gibbsite and diasporic bauxite with Calcification-Carbonization method, the effect of calcium aluminate on dealkalization and dealumination was investigated. The results show that the alumina-silica ratio of these two ores can be both reduced to 0.70, and the sodium alkali content can be reduce to less than 0.50%. It indicates that it's feasible to use calcium aluminate replacing lime. The proposal well solved the problem that aluminum is difficult to recycle at low concentrations and enhances the effectiveness and cleanness of Calcification-Carbonization process which has an extensive prospect.