The effect of particle size distribution of tailings on rheological characterization of paste

Abstract

The rheological behavior of paste, particularly regarding pumpability and in-situ dispersion, is critical for the safe and efficient disposal of mine tailings using paste technology. Therefore, when designing paste mixtures, both rheological and physical mechanical properties must be well defined. The flow behavior of paste is mainly governed by the physical and chemical characteristics of the tailings, among which the particle size distribution (PSD) plays a decisive role. In this study, process tailings from six different mines, iron, boron, silica, gold, marble, and copper were characterized, and the rheological behavior of pastes prepared with each tailings type was examined. The results revealed a clear relationship between the curvature coefficient (Cc), which reflects PSD, and the rheological parameters of the paste. Mixtures containing tailings with Cc values between 1 and 3 (classified as well-graded) exhibited superior rheological performance and pumpability despite having higher solid contents. In contrast, tailings with Cc < 1 or Cc > 3 showed reduced flowability and higher viscosity. For example, the packing density of gold tailings with Cc < 1 was approximately 25%, whereas that of iron tailings with Cc ≈ 1.9 reached nearly 55%. These findings confirm that variations in PSD, as represented by the curvature coefficient, have a significant impact on the pumpability and flow behavior of paste mixtures, offering practical insights for sustainable tailings disposal design.