Published in September 2005 Australian Longwall Magazine
In-situ tests of thermal infrared cameras to help detect the coal mine roof have generated some promising early results. Potentially, the approach could be used for real-time horizon control on both a longwall and continuous miner sections.
CSIRO researchers tested thermal infrared detection, similar to coal interface detection (CID) technology, using a new compact infrared camera set up on a shearer to monitor the drum and newly cut roof in an operating mine. Tests were also undertaken during roadway development to evaluate the use of thermal imaging.
The tests have shown the thermal records clearly indicated when harder roof material was being cut, which means it would be possible to automatically perform CID at the roof, using image processing techniques.
"In addition, in a previously unreported discovery, thermal signatures were discovered in the face due to the action of the drum on particular bands within the coal seam itself," CSIRO reported.
"This information holds great promise as a reference for real-time horizon control." The method would allow thermal traces to be obtained in a similar way to the optical marker band detection process to establish roof and floor horizons.
Thermal imaging has advantages over the optical method in that the thermal signatures can be detected from a shearer-mounted sensor that can perform better than visible light cameras.
CSIRO, which has patented this approach for horizon control, said shearer manufacturers would need to provide a secure mounting location for the IR camera.
Funded largely by the Australian Coal Association Research Program with CSIRO as principal research group, the longwall automation project has been ongoing since 2001.
Australia's top research project in underground coal mining automation is attracting much interest in the US coal mining operations.
The project aims to develop a longwall automation system that will cut and load coal, maintain face geometry and manipulate roof supports without human intervention.
On a recent trip to attend Longwall USA, mining manager CSIRO exploration and mining, Mick Kelly, found growing interest from companies in automation technology.
The heart of the system is the military grade inertial navigation unit (INU). Extensive trials in Australian mines has shown that the INU has solved the problem of tracking the position of the shearer in three dimensional space and is the basis of the first product, the Shearer Position Measurement System (SPMS). Key to longwall automation, this information will be used to keep the face straight, provide the basis for controlling chock movement and improving horizon control.
The SPMS is on the verge of being market-ready and already mines are lining up to buy one. Semi-commercial versions are being put into service at the Beltana and Broadmeadow mines in Australia and fully commercial versions are expected by early next year.
"What surprised us is the level of interest in the SPMS product only," Kelly said. "It only delivers information and won't solve the horizon control problems on its own. It is however, the heart of the entire system onto which other products can be attached."
And what an array of products and gadgets there are to choose from.
The first phase of the product release will deliver shearer position measurement, automatic face alignment, automatic creep management and a horizon control system based on the INU.
