This report outlines the study conducted on evaluating the excavator dig methods at the Tarong Coal mine site with the support of Rio Tinto Coal Australia. This study investigates the comparison between the single flitch method and the double flitch method in regards to the efficiency, productivity, reliability, and overall effectiveness achieved.
There has been conjecture between the company and the equipment supplier, as to whether the double flitch method with the excavators is in fact favourable over the long term, or not. The use of the double flitch method is believed to yield higher productivity, however there has been no formal study or investigation into the true benefits and/or long term effects it may have on the equipment.
The double flitch method is the digging technique where the excavator is positioned on top of a bench which it is extracting and simultaneously removes a second bench, located next to the excavator and above the bench it is operating from. The haul truck being loaded is positioned on the pit floor., in front of the bench, The dig cycle begins with the overhand dig method as the bucket moves through the upper bench face dragging the rock downwards into a pre prepared trench in front of the machine. The bucket then completes the dig cycle with a standard underhand dig method as it loads the bucket.
As a result of the thesis study, it has been shown that the dig methods employed do have a direct relationship with the overall performance achieved by the excavators and that there are a number of variables that have a significant effect on this performance recognised. It was found that the variable which has the greatest influence on the overall performance of the double flitch dig method is the digability of the material, particularly in the upper section of the face.
The results indicated that the overall performance of the double flitch dig method is much higher than that of the single flitch method when compared using consistent conditions. It was also evident that the double flitch method is capable of sustaining higher levels of performance, considering different operating conditions.