ADJUSTMENT OF THE BAYER PROCESS TO OBTAIN GIBBSITE FROM MEXICAN ALUNITE

The cycle of the Bayer Process to obtain gibbsite from Mexican alunite , previously conditioned by thermal treatment at 650-680 degrees C, de sulphated and hydrolyzed in an ammonia medium, has been established. M ole ratios of Na2O:Al2O3 from 1.75 to 2.00 and temperature leaching di lution at 80 degrees C, hydrothermal elimination of the soluble silica at 150 degrees C and controlled hydrolysis of the solutions at 60 deg rees C, allowed the benefication of the alunitic alumina without letti ng the silica interfere significantly in the quality and quantity of t he gibbsite obtained.