Separation and disposal of sandy fraction in processing bauxite involves removing aqueous sodium hydroxide solution from hot mixture in hydrocyclone and separating sand, red mud and residual solution on screen

摘要

Separation and disposal of the sandy fraction of red mud from processing bauxite with hot aqueous sodium hydroxide solution involves separating the hot mixture in a hydrocyclone to give (a) aqueous NaOH saturated with (I) at the top and (b) sand and red mud at the bottom. (b) is passed to a screen to separate residual NaOH solution, sand and dewatered red mud as filter cake. A process concerns separation and disposal of the sandy fraction of the red mud obtained in processing bauxite with hot aqueous sodium hydroxide (NaOH) solution, using a hydrocyclone. The hot mixture of aluminum hydroxide (I) dissolved in NaOH solution, sand and fine-grained red mud from a collecting tank etc. is separated in the hydrocyclone to give aqueous NaOH saturated with (I) at the top and sand and red mud at the bottom. The bottom fraction is passed to a screen, so that residual NaOH solution is returned to the tank, the sand is sifted out and the dewatered red mud is removed as filter cake. The deposits on the screen are removed by cleaning, when necessary, with preferably hot, unsaturated aqueous NaOH solution. An Independent claim is also included for the equipment used for separation.