Flotation separation of diaspore from aluminosilicates using commercial oleic acids of different iodine values

Abstract

A systematic study of diasporic bauxite flotation using commercial oleic acids with different iodine values as collector was conducted in this paper. Bench scale flotation tests for diasporic bauxite ore and micro-flotation tests for relevant pure minerals (including diaspore, pyrophyllite and kaolinite) were carried out at different conditions using commercial oleic acids with iodine values of 65, 121 and 131. The results suggest that an increase in the iodine value of oleic acid would lead to improved flotation separation of diaspore from aluminosilicates. Use of the commercial oleic acid with iodine value of 131 in closed-circuit flotation tests allowed us to obtain a concentrate with alumina-to-silica (A/S) ratio of 5.33 and alumina recovery of 85.56% from the feed ore (A/S ratio = 3.39). Chemical analyses of these commercial oleic acids found that an increase in the iodine value was associated with increased proportion of linoleic acid in the commercial oleic acids. To fundamentally understand the correlation between the iodine value of commercial oleic acids and the efficiency of flotation separation of diaspore from aluminosilicates, the computational studies of frontier molecular orbital energy of oleic and linoleic acid were done, and the results suggest that linoleic acid has higher chemical activity than oleic acid and its chemical adsorption on diaspore is more stable than that of oleic acid.