Effect of cationic surfactant addition on the electrokinetics and stability of silica/kaolinite suspensions in copper hydrometallurgy conditions

Abstract The presence of small particles at operating conditions of the hydrometallurgy process forming the crud is a complicated issue. These particles, most often silica and clays, remain in the suspension or float to the top. A potential solution for their elimination could be to promote the sedimentation of the solids by the addition of surfactant. However, such a procedure in these complex systems, with different kinds and sizes of particles, requires the evaluation of the composition and optimal dose of surfactant. In this work, we explore the use of dynamic electrophoretic mobility for indirectly evaluating the adsorption of CTAB on silica/kaolinite mixtures at low pH, high ionic strength, and particle concentration above 3%. The electroacoustic technique (ESA) shows to be suitable to predict the effect of surfactant addition on the individual particles of silica and kaolinite and mixtures of them. The conclusions were in agreement with sizes and sedimentation rate determinations. Moreover, scanning electron microscope (SEM) images confirm the evolution of aggregates and the formation of structures between particles by the addition of CTAB. Since the final aim is the identification of the optimal doses of surfactant in which the described suspensions flocculate and separate from the continuous phase, this investigation can potentially contribute to solve operational problems associated to the generation of crud in the hydrometallurgy process.