Optimisation of performance of dispersants in aqueous plasma dissociated zircon suspension

Abstract

Plasma dissociated zircon (PDZ) is a unique product obtained during in-flight dissociation of zircon sand in a plasma reactor. In PDZ, submicron zirconia crystallites are intimately mixed with glassy silica. This paper describes the selection and optimisation of dispersants in controlling stability of an aqueous suspension of PDZ. It has been observed that inorganic dispersants and organic additives give clearly distinct behaviour. In both cases, optimum dispersant dosages can be obtained from the streaming potential characteristics. It is shown that there is a critical concentration of each dispersants, which gives the highest streaming-potential/surface charge and hence optimum performance. Studies showed that the isoelectric point of PDZ particulate is at pH 2.8. Additions of dispersant increase the charge in magnitude and modified the surface to have more negative charge in the pH range 2.8-9.4. An assessment of particle/additive interactions, overall stability, and optimised chemical additive required to obtain homogeneous, well-stabilized suspension can be derived from the streaming potential characteristics. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.