Abstract

The paper presents the results of the research into the influence of the sizes of grain (-10 - +7; -5 - +2,5; -2,5 - +1,25; -0,074 mm ) of the Bauxite Laterite in South Viet Nam on the dissolving Gibbsite in the caustic aluminate solution ( 0 = 3,915; c = 1,6; Na2O = 190,1 gr/l ; t = 140 ±5°C ; t = 2 h ). The speeds of the dissolving Gibbsite of all the sizes of grain have satisfid the requirements of the Bayer process moreover the characteristics of the Red Mud had been improved rather better when we used the sizes of grain bigger than 2,5 mm.