STUDY RHEOLOGICAL BEHAVIOR OF A INDUSTRIAL LATERITE SUSPENSION

Abstract

The rheological properties of an industrial aqueous suspension from the acid leaching processing, in Moa, have been studied. The physical –chemical analyses indicated that the sample was mainly composed by goethite, as the major mineralogical phase, and gibbsite and serpentine, as secondary phases. The sample showed a wide range of particle size distribution, with a large amount of fine particles. A three parameter non linear relationship was used for describing the cumulative size distribution. The rheology of the studied suspension was determined as a function of solid concentration and pH. Flow curves for 25 and 47.5 % by weight of solid fit into the Bulkley-Herschel model, and flow curve for 10 % by weight of solid showed a pseudoplastic flow which can best be described by the Ostwald de Waele model. The apparent viscosity of the suspension is strongly dependent from pH, reaching the maximum at pH value around the point of zero charge  (p.z.c=5,7). At pH values which are far from the p.z.c, low viscosities are obtained. In this work it was applied a statistical design of experiments 2K to examine the effects over
suspension apparent viscosity of three factors and their interactions: solid concentration, pH difference (p.z.c-pH), and temperature. Results showed that all factors and their interactions were statistically important, being the most important of them: solid concentration, pH difference and
the interaction between these two factors.