Document Type

Conference Paper

Publication Date


Publication Details

This conference paper was originally published as Trueman, R, Lyman, G and Cocker, A, Managing Roof Control Problems on a Longwall Face, in Aziz, N (ed), Coal 2008: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2008, 10-21.


A proven way of interpreting the shield leg pressure sensor data within each shield load cycle has been developed by the authors and this has been encapsulated into real time and non real time software. A load cycle is the change in support pressure with time from setting the support against the roof to the next release and movement of the support. It is now possible to automatically identify when a shield has too low a set pressure, and when a shield is faulty and/or has an inadequate capacity for the conditions. It has been found that once set conditions deteriorate and shields are set manually it is very common for set pressures to be too low for the conditions, resulting in roof control problems. The software can automatically identify set pressures that are too low which will enable auditing of shield operation and corrections to be made. Up to 10% of shield legs have faults on a typical Australian longwall and these periodically result in localised roof control problems. Faulty support components are automatically identified, enabling timely repairs to be made. On some longwalls the shields become overloaded at the peak of the periodic weighting cycle and the software can identify the difference between a heavily loaded support and one that is overloaded. By minimising the cycle time and making sure that set pressures are adequate in cycles following the overloading event, it is quite possible to successfully mine through an overloading event if the event is correctly identified. The use of this software has the potential to significantly reduce or even eliminate roof control problems on a longwall face with significant benefits to both productivity and safety. By automatically identifying potential causes of roof control problems and offering solutions, the software has the potential to aid longwall automation. A Beta test version of the real time software has been successfully working at BMA’s Broadmeadow Mine for some time and several mines have benefited from expert off-line analyses using the software. The software can also be used to isolate the many interconnected factors affecting roof control on a longwall face, which will enable their quantification and is therefore a powerful research tool.