Drill monitors for rotary blasthole drills have been available to
the mining industry since the 1970s. The early monitors were
pen strip chart recorders that were developed for the oil drilling
industry and adapted to mining. They recorded drilling
parameters such as depth, pull-down pressure, torque, RPM, and
hailing air pressure. While these recorders could generate a large
volume of paper, the amount of useful data was minimal. The
data was not summarised and required an engineer to interpret the
chart traces. Being a mechanical recorder, the devices were also
susceptible to frequent failures. Modem electronics, and the development of the personal
computer and its associated software have radically changed the
type of instrumentation that is now available for blasthole drills.
Perhaps more important is what can be done with the data. The
PC allows the logged data to be analysed, summarised, and a
variety of reports to be generated. The reports can be customised
to meet the specific requirements of the mine and reduce the
amount of time that is required to interpret the data. There is also an increased awareness in the mining industry of
the importance of production drills. Blasthole drills have
typically been the piece of production equipment that received
the least amount of attention in a surface mine. Management
focussed on the trucks and shovels or draglines. This situation is
changing, and therefore the benefits that can be derived from
monitoring drill performance are being recognised. Potential
economic benefits of installing drill monitors have been
documented in previous papers (Peck and Vynne, 1992). Mines
are finding that pay-back periods of less than twelve months and
rates of return in excess of 30 per cent are not uncommon. These
benefits include the following: 1. Reduced overdrilling; 2. Increased rate of penetration;
3. Helping to locate coal seams; 4. Identification of weak and strong zones;
5. Reduce geophysical logging; 6. Optimising blasts; 7. Improved fragmentation and diggability;
8. Decreased coal dilution; 9. Increased bit life; 10. Reduced maintenance costs; 1 I . Improved accuracy of data and reports.