Published in June 2007 Australian Longwall Magazine

The technologies are the new wave of research under the Landmark banner, now coined LASC (Landmark Automation Steering Committee). The technologies will soon be deployed at Anglo Coal’s Grasstree mine after initial experiments two years ago at Xstrata’s Beltana mine.

“Traditionally sensing systems have been able to tell us where the coal is to within 1–5m of accuracy so we know roughly where we are going. The sensing we are developing shows you in real time where you need to be cutting to an accuracy of 50mm, and is going to let us take our hands off the steering wheel,” CSIRO Exploration and Mining (CEM) automation group leader David Hainsworth said.

The first technology under development is thermal infra-red cameras. This technology has been around for some time – even finding use in cricket where the camera shows viewers when the ball hits a bat, glove or pad. However, its use in an automation context is new.

The infra-red cameras can sense when the shearer is starting to cut into surrounding strata rather than the coal. The cameras see the hot spots and can alert operators to change the shearer’s direction to stay within the seam.

CEM senior research engineer Jonathon Ralston said the team plans to mount the cameras, housed in small flameproof enclosures with a window transparent to thermal infra-red radiation, on the roof supports.

Combining images from each camera could then provide a full panoramic view of the face. Ralston said the decision to mount the cameras on the shields was prompted by survivability – previous trials at Beltana where cameras were mounted on the shearer struggled to cope with the rough conditions.

Since the original trials the cameras have reduced significantly in size and complexity. With this development, the CSIRO team are confident to once again deploy cameras on the shearer to enhance the information gathered by those on the shields.

Besides picking up rock outside the seam, researchers are also excited about the promise the technology holds for picking up heat differences within the exposed coal face. Past trials showed the cameras picked up heated areas within the seam that were not visible but strongly related to the layered structure of the coal (or piles).

“Interfaces between coal layers within a seam are often subtle and difficult to detect visually but give valuable information about the structure of the seam and are used by experienced operators to give a reference against which they offset the roof and floor cutting horizons to give good seam following,” Hainsworth said.

Working with something more visible, the team also plan to use an array of video cameras mounted on roof supports, combined to show a live panorama of the longwall face. The real-time information derived from the vision sensors will interface with existing mine monitoring and control systems to provide dynamic sensing capabilities essential for efficiently mining the longwall face, accurately locating mining equipment and identifying geotechnical anomalies. The automation technology can also be used to provide horizon sensing capabilities as part of a horizon control strategy.

Ralston added once the technology has been developed the operator will be able to set horizon targets, such as a leaving 1m of coal for strata stability purposes. CSIRO said the two technologies are expected to be commercialised within six months.