Draglines are commonly used to remove the blasted overburden from open cut coal mines. The overburden may be up to 50 m in depth and consists of rock fragments of varying size. Its removal exposes the coal deposits beneath for mining. A dragline is a crane-like structure from which hangs a huge bucket of up to 100 m ³ in volume. This is dragged up the side of the pit and filled with rock. They are an expensive and essential part of these open cut coal operations and even small improvements in performance represent very large economic value. Their performance is affected by many factors, including how the dragline is operated, where the material is taken from and where it is deposited, the design of the bucket, the way it is rigged and the properties of the rock. DEM modelling allows us to study the flow into the bucket, predict comparative fill times and spoil volumes as well as bucket wear, dynamic stresses on the bucket and the performance of the rigging cable configuration. Previously 2D DEM modelling has been used to compare the performance of different buckets (Cleary, 1998c) and the effect of particle shape on fill times and volumes (Cleary, 2000).

Here, we demonstrate DEM modelling of a dragline filling in 3D. The bucket is dragged up to a representative slope of 22 with standard drag speed of 1.75 m/s. The calculations were performed, and the pictures shown, in a reference frame that moves with...