ABSTRACT: Highwall mining is being introduced into central Queensland open cut mines so that coal can be mined from existing high walls, where the overburden depth is too great for conventional surface methods to operate economically. With this mining method, remote controlled continuous miners extract coal from a series of parallel unsupported roadways driven from the base of the highwall, perpendicular to the highwall face, for a distance of up to 300m. The optimal design of the width of the pillars left between the roadways is one of the factors that is crucial to achieving maximal recovery whilst maintaining the integrity of workings
This paper describes a three-dimensional elasto-plastic model of a highwall and the driving of roads into a dipping seam. The model is used to estimate a factor of safety for a particular combination of pillar and roadway widths, and depth of mining. This analysis method was applied to formulate a preliminary pillar design for a central Queensland coal mine.