Blasting Technique Pays Off
- Thiess’ cBLAST software for through seam blasting allows for a visual interpretation of the different waste and coal stratum
- An Aquila Rock Recognition system is used to gather the strata information at the drill hole which allows for accurate explosive column placement
- Outputs from cBLAST are used to reconcile geological models and improve the timing and volume accuracy of the short term-coal mining plan
- Blast design ensures that not only is blast efficiency maximised, but additional benefits include control of and reductions in dust, fume generation, vibration and overpressure on a per blast basis
The Mt Owen Coal Mine in the Hunter Valley is taking mining to another level by making an existing technique more intelligent. In tackling the complex challenges of Mt Owen, Thiess has established itself as the industry leader in ‘through seam blasting’.
Through seam blasting’ uses blast holes that extend through the coal seam down to a nominated drill depth. The technique allows for simultaneous fragmentation of the overburden and inter-burden material which minimises disturbance to the coal seams. It requires inert stemming material to be placed in sequence with the explosive in each hole. Detailed design of each blast is necessary as the sequence and amount of explosives varies both between blasts and between holes within the same blast.
Successive Thiess technical and blasting teams have honed these skills, which are delivering higher reserve recovery and therefore greater value to our client, Xstrata Coal. In December 2010, Thiess was awarded a $1.1 billion extension to our mining contract to operate the mine. This success was helped by our mining team’s capacity to manage the deposit’s technical difficulties.
Mt Owen Project General Manager Jeroen Hendriks said the deposit was complex and differed from traditional strip mines because of its multiple coal seams that dip at angles between two and 45 degrees. The seams vary in thickness between 0.4 and 12 metres. Thiess is currently mining at a depth of 270 metres.
“The deposit presents greater operational challenges than a typical strip mine, which has required us to develop specialised terrace mining and ‘through seam blasting’ techniques for which we are now recognised as an industry leader,” Mr Hendriks said.
“Our people are some of the best in Australia. We have developed this technique in-house using computer modelling and perfected it during the past 16 years.”
