Investigation Of Zeta Potential And Rheological Behaviour Of Suspensions Related To Bauxite Based Al₂O₃-SiO₂ Castables

Flowability of castables is correlative with the fluidity of the suspensions of raw materials and their matrix. It is important to investigate effects of raw materials, solid content and dispersant additions on rheological properties of raw material and matrix suspensions for the sake of improvement of workability, properties and service performance of the castables. Zeta potential values of raw material including bauxite, ultra-fineα-Al2O3, ultra-fine SiO2, aluminate cement used in the bauxite based castables, and the effects of concentrations and additions of dispersants including sodium tripolyphosphate (STP), sodium hexametaphosphate (SHP), cyanuramide(SM), calcium lignosulfonate(FDN) on Zeta potential of the suspensions were investigated by means of ZetaProbe Zeta potential tester by Colloidal Dynamics for concentrated colloids. Meanwhile, rheological properties of the suspensions of raw material, matrix and with additions of dispersants were determined by means of SST viscometer by Brookfield. The results show that: (1) Among the four dispersants tested, STP shows the best dispersing effect both for raw materials suspensions and matrix suspensions, while SHP takes second place, SM and FDN show almost same and a little less effects. (2) Zeta potential values and rheological properties of the suspensions investigated indicate good corresponding relation other. With higher absolute values of Zeta potential of the suspensions, lower viscosity and better stability of the suspensions are obtained. Otherwise, when absolute values of Zeta potential are lower, the suspensions are viscous and unstable.