Maybe the post is old but it could serve other people.
You can use newtonian or no newtonian model for CFD model (is not necesary use particles or DPM)
Tails are considered to have a Newtonian behavior up to approximately 68% solids concentration by weight, above this value their behavior is non-Newtonian, generally modeling as Bingham plastic. This can be seen in the green background graph (for copper tailings and for gold tailings in the white background chart) where for Cp values lower than 68%, the measured properties show negligible
to determine the properties of density and viscosity you can use the book Solid-Liquid Flow Slurry Pipeline Transportation by Edward J. Wasp, p. 46-47.