Discrete-Event Simulation of Continuous Mining Systems in Multi-layer Lignite Deposits

Continuous surface mining systems, employing bucket wheel excavators, belt conveyors, and stackers, are used in the exploitation of most of the large lignite mines in northern Greece. One particular characteristic of these mines is that the deposits consist of a series of lignite layers of thickness varying from just a few centimeters up to several meters, with interbedded layers of sandy and clayey waste material. This multi-layer geology dictates frequent changes of the material excavated on each bench, which adds to the complexity of the inherently stochastic mining system and makes material flow a critical performance parameter.

In this paper an animated discrete-event simulation of such an operating continuous mining system is presented. An extensive statistical analysis of recorded operational data for a period spanning a full calendar year, as well as of the deposit’s spatial variability, provides the empirical distributions used to model input variables. The distribution of material flow at the belt conveyor hub, production estimates, equipment availability and utilization are model outputs. The simulation model is evaluated in terms of its suitability for decision making under risk during mine planning and design.