Queensland mine takes the pressure off

MONITORING and analysing longwall pressures are about to get a whole lot easier for one central Queensland coal mine, which in June will install the just-released interpretive software tool, Longwall Visual Analysis (LVA).

Angie Tomlinson

Published in June 2006 Australian Longwall Magazine

The software, specifically designed for geotechnicians and longwall engineers, gives a graphical analysis of longwall pressures in real-time and historical viewing options.

The status of the longwall can be viewed in 2D and 3D, along with analysis of cycles, trending and face scans, and overlaying longwall data onto mine maps.

The longwall monitoring program is the brain child of Sydney-based Encore Consulting’s Dr David Hoyer and Yeppoon-based Data Manipulation Services’ Alister Waller, and was developed in partnership with the central Queensland mine.

“Together we wanted to develop a package that would work in real-time to give immediate feedback on how the longwall is performing and interacting with the roof. This meant a multi-level approach to manage the large amounts of incoming data, store it safely in databases, analyse it on the fly, and provide instant and efficient visual feedback to the operators,” Hoyer said.

“By monitoring the pressures of your longwall and comparing these against other cycles and data you can help avoid costly downtime and a possible threat to safety.”

LVA analyses cycles and trends, time-weighted average pressures, maximum pressures and set pressures, which can give immediate feedback on whether set pressures are appropriate for strata conditions, and in many cases, the type of supports and legs that may need maintenance attention to correct leaks or data signal errors.

Hoyer and Waller have decided to licence LVA on a per longwall basis, which means operations can use it on as many machines as they like to view and replay historical data, with one machine used as the live data capture/viewing machine.

Waller said as LVA is designed and coded locally, the modules can be custom-made to suit specific mine requirements.

“The analysis of pressures and cycles can easily be customised to any mine’s particular requirements. For example, we are working with a mine that would like to analyse the shape of the pressure trend curves within each cycle, for automatic indication of whether set pressures are correct for the prevailing conditions. The algorithms used for analysing the data can be configured for each mine to suit their conditions, they can also be changed in order to re-analyse historical data so you can tweak certain circumstances.

“LVA is also about making your reporting easier with the automation of some reports and we can also custom build reports to suit your requirements.”

Some of the features include near-real time shield monitoring, analysis, and alarms and multiple panels can be monitored per mine. The program automatically analyses the data and saves the results for TWAP, cycle times, yield/set statistics and periodic weighting.

The 2D/3D design means the 2D views show individual pressures and support cycles in much greater detail than the 3D “big picture”, which in many cases will quickly indicate whether set pressures are too low or too high, and whether some supports may be faulty or need attention by the operators.

One of the key features is the historical pressure readings, which according to Hoyer can be used to review previous longwall events such as periodic weighting events, or inadequate set pressures, and compare with current data.

“There are various algorithms within LVA that analyse cycles, trending and weighting events, and alarm levels; and the user can experiment with these algorithms on historical data before implementing them on the current live data,” he said.

The longwall data can be overlayed onto mine maps that allows the mine management to quickly and easily see an overview of the whole longwall and relate pressures to known areas of weak roof or faults.

“This would be invaluable in hazard and risk analysis, predicting longwall behaviour, or as a training tool,” Waller said.

He said when developing the product, they focused on ensuring that data analysis was the top priority and that the interface was highly intuitive and configurable, without compromising on the visual aspects of the data displays.

“This gives us a competitive edge over other products that may focus more on being a pretty front end, or a relatively simple data collection tool.”

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