Using two-way coupled DEM-SPH to model an industrial scale Stirred Media Detritor

摘要

The Stirred Media Detritor (SMD), is one of the milling devices used in concentrators for fine and ultra-fine grinding applications. The SMD has a vertically orientated octagonal shell which supports a vertical shaft that has protruding impeller arms to agitate the charge. Understanding of the motion and physical structure of the charge during operation in these devices has not yet matured. This paper will explore the flow and interaction of media and slurry in a commercially available SMD 1100E, which has a motor with a power rating of 1100 kW. A two-way transient coupled Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics (SPH) model is used to achieve this. The DEM component represents the ceramic grinding media which is fully resolved while the SPH model represents the slurry (water and fine material). Discharge from and feed into the mill is omitted and the focus is steady state operation. The media size used has a mean diameter of 8 mm with a small variation of ±10% from the mean. A representative fine particle solids loading for the slurry of 40% is used, giving a viscosity of 2.2 mPa s. Newtonian rheology is assumed since the slurry solids loading is less than 50%. The mill is charged with 12 t of media and 4.44 m3 of slurry. The paper also explores, through the use of the model, energy utilization, mixing and transport efficiency in the SMD 1100E.