Minerva Mine experiences unique geological conditions among Bowen Basin coal mines. In particular, the steeply dipping, multiple thin seams mean typical drill and blast techniques may not be the most effective. Blast design parameters and predicted fragmentation based on a Kuzram fragmentation model adapted by Lilly (1986) were recorded over a nine month period from November, 2005 to July, 2006. These variables were then compared to the productivity achieved while excavating the individual blasts to determine if relationships existed, which could be used to design future blasts for increased productivity.
The results of this analysis showed that none of the parameters studied showed any correlation with productivity, and therefore no recommendations for future blasts could be made. The results did show that some of the blast design parameters, in particular the bench stiffness ratio, were outside the normal ranges and should have indicated poor blasting
results. In reality, this was not the case, possibly indicating the bench stiffness ratio has limited use on thin benches.