Sedimentation analysis and the aggregation stability of aqueous alumina suspensions

The results of sedimentation analysis of the ground G-0 grade alumina powder, representing a mixture of alpha and gamma aluminum oxides (according to the results of X-ray analysis) are presented. It was established that particles in aqueous suspensions may be disaggregated due to an increase in the hydration time, followed by ultrasonic treatment, as well as by adding sodium tripolyphosphate to the dispersion medium. This additive ensures both the reversal of charge and an increase in the absolute value of the particle electrokinetic potential. To process the sedimentation curves, an analytic method proposed by Tsuryupa was applied. It was shown that the powder investigated is essentially a bimodal system, which may be separated by sedimentation into two main fractions as carefully as possible.