Research On The Reaction Behavior Of Titanium During The Process Of Dissolving High Titanium Bauxite Through High Pressure Hydration

The development and utilization of high titanium bauxite can greatly alleviate the trend of China's bauxite ore supply crisis and sharply depleted ore grade,while the conventional dissolving out of high titanium bauxite through Bayer has high titanium content,which caused alumina dissolution rate decreased and hard to be used in large-scale.Therefore,the exploration of new leaching technology of high titanium bauxite has great the significance for the sustainable development of alumina industry in China.High pressure hydrothermal method is a new method for the treatment of the loss of Al₂O₃ and Na₂O in high silicon bauxite through Bayer method,its main principle is that dissolving out bauxite under the condition of high temperature,high alkali and high ratio.High titanium bauxite are dissolved out through high pressure hydrothermal method in this paper,conditions that affect the alumina dissolution rate and the reaction behavior of titanium through high pressure hydrothermal method were explored,which provide a reference for the development and utilization of high titanium bauxite.The mineralogical properties of high titanium bauxite showed that the selected ore belongs to diaspore type high titanium bauxite,the content of Al₂O₃ is 51.31%,the aluminum silicon ratio is 8.21,the content of TiO₂ is up to 7.21%.Minerals containing Ti in the ore mainly in the form of anatase,then there is a certain amount anatase and a small amount of brookite,anatase in the form of regular or irregular clumps or inclusions disseminated in the ore matrix.The test results show that alumina dissolution increased significantly with the increase of temperature,caustic concentration and mother liquor ratio.The optimum digestion conditions according to the high pressure hydrothermal method as follows:the dissolution temperature is 290?,the caustic alkali concentration is 360g/L,solidcontent is 275g/L,lime dosage is 8%,leaching time is 60 min,the molecular ratio?MR?is 30,the actual dissolution rate of Al₂O₃ reached 87.29%,relative dissolution rate of Al₂O₃ can reach 99.34%,the residual rate of TiO₂ is 2.74%;comparing with that the dissolution temperature is 270 ?,caustic concentration is 260g/L,molecular ratio?MR Bayer?is 3.4,the actual alumina dissolution rate of Al₂O₃ is only 77.74%.which indicate that high pressure hydrothermal method help alleviate titanium minerals hindering the alumina dissolution,which can further improve the dissolution rate of Al₂O₃,and reduce the residual rate of TiO₂ in solution.The mechanism analysis of high titanium bauxite through high pressure hydrothermal method showed that the method is beneficial for transfering the minerals containing Ti into perovskite,and alleviate the retarding effect of TiO₂ on bauxite dissolution,promote the hydration of garnet,increase the saturation index of Si in garnet,thus reducing the loss of Al₂O₃ and Na₂O in the process of high pressure hydrothermal,improve the dissolution rate of Al₂O₃.