Dr Timothy Donohue

Dust emission is one of the main problems in the operation of transfer chutes. The design of the transfer chute heavily influences any potential dust generation. Although this influence is well known, much more attention is given to active dust suppression via water spray systems, the exhaustion of the dust polluted air or the use of electrostatic filters rather than the design optimization of the transfer chute.

This article presents the outcomes from a series of physical experiments to measure the air entrainment rates encountered within a stream of freefalling particles. The experimental work presented spans a range of particle parameters and hopper geometries. From these results a new theory for the prediction of air entrainment is developed and presented. This new method was developed specifically to facilitate a better understanding in the area of fugitive dust control associated with material handling systems, which are driven by the air entrainment during freefalling. From the work presented in this article, a better prediction capability of freefalling bulk materials in either constrained, or unconstrained systems, will allow for the optimization of either passive or active dust control strategies. This article presents several distinct sections that detail the experimental work used to determine the freefall stream parameters that were conducted to allow the development of the entrainment equations. © 2013 Taylor & Francis Group, LLC.

A co-operation among Universities of Newcastle, Australia, and Magdeburg, and Germany, is established to develop and apply the new analysis methods such as Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), for prediction of diffuse dust emission from dust exhaustion plants. The combined analysis of DEM and CFD includes two CFD simulations, the air flow in the bulk material stream and the air flow around the bulk material stream. The boundary conditions for the calculation of the air flow in the enclosure are set. The results of CFD simulations show that the exhausted air does not come from the impact zone of the material stream on the receiving belt conveyor, but from the opening above the incoming conveyor belt. It is also found that the air with the highest dust content can be found on top of the receiving conveyor.

Open front inclined apron feeders are used widely in the mining industry to transfer run-of-mine ore into primary crushers. In the design of these apron feeders it is necessary to understand the mechanics of the feeding action at the hopper/feeder interface to allow for accurate determination of the power requirements of the drive unit. The focus of this particular study is to present current theory that can be used for the prediction of the shear force at the feeder belt interface and the corresponding power required for the feeder. A continuum theory approach is presented in conjunction with Discrete Element Modelling (DEM), with both of these results then compared to experimental results from the laboratory.

A technique to simulate airflow around transfer chutes that involves linking Discrete Element Method (DEM) commercial package Rocky and Computational Fluid Dynamics (CFD) commercial package ANSYS Fluent is proposed. The flow of particles is first calculated in the DEM domain; after that continuum parameters of this flow (porosity, mean particle size and cell-averaged particles velocities) are calculated and used as input into ANSYS Fluent CFD package for the solution of the airflow. This solution is carried out using a single-phase moving porosity approach with User Defined Functions (UDF) for porosity and particle-based momentum terms in Fluent based on phenomenological interaction laws. The comparison against experimental results for a laboratory-scale transfer chute demonstrates a good match between experimental and computational data. Several turbulence models and particle-gas interaction laws have been tested and it was concluded that for this problem the choice of interaction laws and turbulence models does not affect the results of the simulation to any significant degree.