Much of Coaltech’s research has focussed on re-assessing reserves including abandoned and defunct collieries that may have some areas of unmined coal.

Researchers are also looking at returning to hand-got bord and pillar mines which generally have roof and floor coal in situ as well as the pillars, which could be extracted using modern equipment.

“To this end we have a group of rock engineers who have specialised in coal mining rock mechanics and have done a great deal of research into the stability of pillars, especially the effect of time,” said research mining engineer Andy Johnson.

One project currently being carried out is examining the formulae used to calculate the safety factor of pillars and to establish a seam specific formula based on the varying strengths of the coal in the various coal seams.

Another area of research has been into different mining methods, including types of rib pillar extraction and other high extraction methods.

Future projects on the CSIR Coaltech agenda include coal and stone cutting techniques in seams with stone inclusions, the clearance of coal behind the cutting machine in thin seams and the rock mechanics implications of undermining surface features such as streams and other water features.

South Africa still has considerable reserves in seams with a thickness of below 1.4 metres. Coaltech projects have actively looked into the best ways to economically mine these.

“The most likely method to succeed is longwall mining, however the capital costs are prohibitive, in fact only 4 installations are operating currently in South Africa and only one in sub 2.4 metre seams,” Johnson said.

Projects completed under the Coaltech banner include research into an activated suppression system. This system comes into play if a cutting machine ignites methane. The sensors on the machine activate a suppression unit fitted to the machine to prevent the flame travelling outbye of the cutting drum.

Trials were carried out at the CSIR’s Kloppersbos facility, using simulated ignitions and high speed video photography to prove the efficacy of the system. There are currently three installations in use in mining areas known to be susceptible to methane release.