Separation of diaspore from bauxite by selective flocculation using hydrolyzed polyacrylamide

Selective flocculation is a new method to solve the problem of China’s bauxite de-silication besides flotation and reverse flotation. The method of selective flocculation of bauxite using hydrolyzed polyacrylamide as flocculant was experimented and evaluated. The results of diaspore and kaolinite single mineral settling tests show that the difference between settlement yield of kaolinite (settling 15 min) and diaspore (settling 3 min) increases from 16% to 60% by adding flocculant at pH=7. Results of selective flocculation experiment of bauxite show that the higher concentrate grade (65.75) and Al-Si ratio (7.34) could be obtained with sodium carbonate as dispersant compared with sodium hexametaphosphate; under the action of flocculating agent, the concentrate grade and Al-Si ratio increase to 67.99 and 9.01. These results could meet the requirements of Bayer production, and the simpler process was expected to cost far less than traditional flotation method and a promising de-silication method of bauxite.