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| CSIRO | SOLVE | Issue 11 | MAY 07 | |
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ARTICLE
By Olivia Hill-Douglas
A marriage of communications technologies and raw mechanical power is removing people from danger and lifting coal mine production.Deep underground in an Australian black-coal mine, 15-metre-long machines drive rotating cutting heads, extracting ore seams up to five metres thick. It is noisy, dusty and potentially explosive. This is the world of longwall, machine-based mining. Such mechanised mining accounts for about 90 per cent of Australian underground black-coal production – some 70 million tonnes a year, or almost a quarter of the country’s overall production. Making longwall coal mining safer and more productive has been the subject of a long-running CSIRO project funded by the Australian Coal Association Research Program, which has also come up with new technology designed to locate and guide coal-cutting equipment in longwall mines.
CSIRO has produced commercial-standard automatic face-alignment systems, which ensure the cutting drums follow the coal seam accurately. Pre-commercial prototypes are now being used at Xstrata’s Beltana and BMA’s Broadmeadow longwall mines. CSIRO has also created prototypes for automatic horizon control and longwall information management systems, which are ready for commercial production. “The project goal was to provide automated systems that would allow people to move away from the hazardous environment,” says Dr David Reid, principal research engineer with CSIRO Exploration and Mining. That means having people close enough to the face to handle exceptions, but far enough away that they are protected from immediate danger. “If you can move people even 50 metres away from the workface you can improve safety, because they are away from the mechanical and hydraulic energy and dust,” he says. In longwall mining, parallel tunnels up to 400 metres apart are driven (sometimes for several kilometres) horizontally through a coal seam. They are then connected by a cross tunnel that exposes the coalface. A massive shearing machine is driven back and forth along this face, taking off slices of coal – much like a deli slicer cleaving ham. The cut coal falls on to a conveyor, while hydraulically powered roof supports attached to the conveyor progressively advance as the shearer cuts into the face. The empty space behind – the goaf – collapses. In an automated system there needs to be reliable communication between the components. So the research group first developed a high-capacity underground communications system, at the same time creating an industry standard for data communication. They then tackled the automation of the machinery itself. This required a twofold solution: a patented positioning and guidance system to ensure the shearer maintains its alignment to the face, and a second system – horizon control – to make sure the cutting drums are at the right level vertically to cut across the heart of the face. However, the overriding concern of the research team was improving mine safety. “It really is a hostile environment down there,” Dr Reid says. “The focus, therefore, is to make it safer and consistent with more normal industrial standards.” Xstrata’s Beltana longwall mine uses the new technology, and engineering coordinator Peter Henderson says it has been a boon.
“Letting machines do the repetitive work, and allowing humans to monitor and correct the automated process, has made this form of mining much more productive,” he says. “And not only has the mine become more productive, but the safety of our people has been improved by reducing their exposure to dust and fly rock from the shearer.” In 2006, for the third year in a row, Beltana was the highest producing longwall mine in Australia, at 6.8 million tonnes, and managed to top its nearest rival by almost 2 million tonnes. It is a safe bet that other longwall mines will be queuing up to take advantage of the new technology as well. For further information contact: |
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