Rheology, the study of the flow and deformation of substances, is of particular importance for wet mineral processing. Especially for fine particle suspensions, in which the presence of solid particles complicates the rheological properties. Meanwhile, surfactants are widely used in the process of wet coal beneficiation, affecting the particle characteristics and rheological properties of coal suspensions. In this study, the quantity density, chord length distribution, Zeta potential and viscosity of coal suspensions with three types of surfactants were investigated, and the effects of surfactants on the rheological properties and particle characteristics of low concentration coal suspensions were discussed. The results show that the anionic surfactant (sodium dodecyl sulfate) can reduce the viscosity of low concentration coal suspension. The cationic surfactant (cetyl trimethyl ammonium bromide) and nonionic surfactant (Triton X-100) have the thickening effect on coal suspension. The anionic surfactants increase the surface potential of coal particles, resulting in the increase of electrostatic repulsion between coal particles and the decrease of viscosity of coal suspension. According to the DLVO theory calculations, the cationic surfactants can reduce the surface potential of coal particles, thus weakening the electrostatic repulsion between coal particles and enhancing the viscosity of the suspension. The nonionic surfactant has less effect on the surface potential of coal particles, but there is a single layer of hydrogen bond adsorption on the surface of coal particles, resulting in an increase in the viscosity of suspension. When the nonionic surfactant is adsorbed completely on the coal surface, the suspension viscosity will be reduced, but it will be higher than that without surfactant.

rheological properties,particle characteristics,surfactant,DLVO theory,coal suspensions