Burton mine lies in the Bowen Basin, about 150 kilometres south-west of Mackay in Queensland. The Burton mine was one of the first mining operations to use the terrace mining method for extracting steep seams. With the approval of the Burton widening project, Peabody planned to modify the terrace-mining concept to a depth approaching 230 metres at the high wall, which would be an Australian first.
In order to minimise the impact on the exceptionally high highwall at Burton all blasts are designed to minimise the impact on the highwall in terms of blast vibrations. The extended life for the highwall in combination with wedge failures in the highwall prompted the need to try and minimise fatigue on the highwall.
Trial set up
By determining the resonant frequencies of the highwall we were able to alter the timing design using electronic detonators to create an artificial frequency within the frequency spectra with a high dampening effect. This created “false frequency” with minimal resonance has the potential to reduce vibration levels at the highwall as well as reduce the duration of the energy which in turn has the potential to reduce fatigue.
The new method was developed using the Transfer Function the total frequency spectra between 2 monitoring points to determine the resonant frequency between the points. The new method showed an extra ordinary accuracy in determining the fundamental frequency and all its harmonics
Highwall Fundamental Frequency and its Harmonics
