There have been a number of attempts to combine Bayer and Sinter technologies in an effort to find an economic means of processing low grade bauxite. To date none of these has really proved that successful and all bar some plants in China and one in Kazakhstan have closed.
The one combination variant that does stand a chance of success, in a low cost country such as China, is the Red Mud Sinter (RMS). In this variant the mud from the Bayer plant is sintered allowing the reclamation of most of the caustic soda and alumina that would otherwise be lost to the red mud. To be successful the cost of energy and interest on capital for the extra plant required must be less than the cost of lost alumina and caustic that would otherwise occur.