Prediction of particle flows and blockage problems in realistic 3D transfer chutes

Chutes are commonly used to re-direct the flow of bulk solids at interchange points in a conveyor assembly. Requirements for the efficient handling of material at high tonnage rates place constraints on chute design. Poor design can result in chute blockages, both static and dynamic plugging, spillage, and reductions in chute conveyor belt life due to uncontrolled wear. Particle attrition often occurs, leading to unwanted dust generation and degradation of material. Numerical modelling of material flow in a transfer chute can help prevent costly mistakes by identifying poor flow properties in the design or implementation of the chute prior to it being put into operation. The entire system is rarely studied as a whole. Often different models are used separately for the different stages of the flow such as discharge, sliding, impact and free-fall. An alternative is Discrete Element Modelling (DEM) which tracks the motion and interactions of all the individual particles in the bulk material and provides a powerful tool for studying such complex granular flows. This paper discusses the use of DEM to aid in the design of bulk materials handling transfer chutes and reports on 3D DEM simulation of material flow in a series of real conveyor assemblies using realistic non-spherical particle shapes. The DEM method is shown to be a useful tool allowing extraction of many selective parameters that are difficult to isolate using a continuum based approach. DEM is also a valuable visualisation tool to better understand the flows in chutes.