Effect of oleic acid on gibbsite precipitation from seeded sodium aluminate liquors

Effect of oleic acid on precipitation ratio, agglomeration and morphology of gibbsite was investigated at selected conditions. The results of titrimetric analysis suggest that oleic acid inhibit gibbsite precipitation from seeded sodium aluminate liquors, and the inhibitory effect is stronger at 65 °C than that at 75 °C. The variations of particle size distribution (PSD) indicate that the agglomeration of gibbsite is significantly enhanced when the concentrations of oleic acid are in a low range (0.01 g/L–0.05 g/L). However, relatively higher concentrations of oleic acid (> 0.1 g/L) suppress agglomeration. The morphology of gibbsite was examined with scanning electron microscope (SEM). It shows that low concentrations of oleic acid in the sodium aluminate liquors lead to the formation of compact gibbsite particles, while high concentrations of oleic acid favor the growth of smooth texture of gibbsite surfaces, that is, the growth habit of gibbsite crystal changes under the influence of oleic acid.