Analysing the effectiveness of the 1750 tonne shields at Moranbah North Mine

Moranbah North Mine has a challenging geotechnical environment that historically resulted in cavity formation on the longwall face with its an associated reduction in productivity. Due to the complex geology at the mine, the increased depths of cover in future panels and the aging of the previous 980 t shields, longwall face stability became a concern. In order to ensure effective strata control in future panels, a new set of 1750 t powered supports were installed into the longwall 108 panel in 2009. These shields were, and still remain, the highest rated capacity shields in the world. This paper presents the results of an investigation into the effectiveness and necessity of the new powered supports. The investigation was undertaken in the form of a comparative analysis to determine the relative effectiveness of the two sets of different capacity shields by analysing the performance of the shields in panels that were directly adjacent and, subsequently, subject to similar conditions. Anglo American has plans to commence two additional longwall mining operations in the same region and the outcome of the investigation will allow the suitability of the larger capacity shields to be determined for the future operations