During a period of twelve months between FY18-19, a series of trials were conducted to compare production drilling accuracy using two different methodologies, and the subsequent impact this had on stope performance (dilution and recovery).
Testing was conducted at a series of underground mines in Australia. The drill rig’s existing alignment processes were compared to a new technology system, with the following observations:
• The new technology was proven to limit rig alignment error, thereby reducing average blasthole deviation, resulting in an increase in the number of holes drilled within tolerance by up to 160%.
• The increased accuracy reduced stope dilution significantly by reducing over-break of subgrade ore, whilst also increasing drilled meters (faster stope-cycle time), reducing the bridged tonnes ratio, and facilitating the capture of previously uneconomical stopes.
A cost-benefit analysis extrapolated from each of the trials showed the extent to which the new technology, when applied to production data, reduced average dilution, increased ore recovery as well as general drill and blast productivity.
In one such trial, the new technology was proven to have reduced average dilution by net 45.4%, which if applied to a full year’s production data, would result in AUD8.2M additional ore recovered, with AUD4.5M less spent on wasted cost of haulage and processing of diluted ore. As a result, return per tonne would increase 22%, from AUD87 to AUD106. This improvement was maintained over the following 12 months – reducing average dilution from 22% in FY17 to 12.1% in FY19.