Numerical investigation on solids settling in a non-Newtonian slurry inside a horizontal flume

TL;DR

This study uses numerical modeling to analyze how multisize solid particles settle in a non-Newtonian slurry within a horizontal flume, considering factors like particle size distribution, inclination, and bubbles, providing insights for industrial slurry management.

Contribution

It introduces a validated 3D Eulerian-Eulerian model with Hershel-Bulkley rheology to simulate multisize particle settling in non-Newtonian slurry in a flume, including effects of bubbles and inclination.

Findings

Particle size distribution significantly affects settling behavior.

Flume inclination enhances settling of fine and coarse particles.

Bubbles influence the settling velocity and behavior of solids.

Abstract

Slurry transportation is always crucial for many industrial processes. This study numerically investigates the settling behavior of multisize solid particles in a non-newtonian slurry inside a semicircular open channel (flume). The non-newtonian slurry is modelled using a three-dimensional (3D) unsteady Eulerian-Eulerian (E-E) model coupled with the Hershel-Bulkley (HB) rheological model. A detailed sensitivity analysis of drag models is performed to establish the solid-fluid interaction in the slurry flow. The numerical model is validated with the experimental data from the literature and shows a fair agreement. The validated model is used to simulate the settling behavior of the slurry in the flume. The mean particle diameter of the solid particles in the slurry is in the range of 75-296 $\mu$m with a median diameter of 188 $\mu$m. The effect of particle size distributions (PSDs), flume inclination, bubble size and bubble volume fraction on the particle settling inside the flume is investigated in the parametric study. The analysis of our results revealed that the settling of solids is significantly affected by PSDs in the open channel system. In particular, the increase in flume inclination progresses the settling and dissipation of fine and coarse particles, respectively. Additional simulations showed that the inception of bubbles influences the settling velocity of solids, which changes the settling behavior of multisize solids inside the flume. The presented study can be used as a valuable guideline for the optimisation of intermediate exclusion of water from thickened slurry in order to ensure the stability of tailing storage facility.