Operational Design Tips for the Drill and Blast Engineer

Does the design line up?

When it comes to drill and blast design, simple and consistent will often achieve the best productivity and blast outcomes. So, where you can, try to keep it simple – if you can’t keep it simple you had better put the effort in to communicate it! Remember: You can have the best design in the world, but if you can’t communicate it, no one will ever know.

Here are some things to look out for:

  • Hole naming – make it simple, logical and extendable
    • You should have a good idea of what you are planning to blast. So, try to design your naming convention around that – but have the contingency in place that if you needed to extend the pattern, you could. For example: if you start your pattern at “A1” you may have to extend your pattern in the direction where you would see “A0”. For this reason, I prefer to start my patterns at A100 or A200 – If things don’t go to plan, at least the naming convention will remain sequential if you have to extend your pattern. Similarly, if you may be able to add more rows, don’t start at A. See below:

Image 1 MEC

  • Hole alignment – Line your holes up!
    • A lot of designs I have seen have a slight offset between rows. When drilling angled holes, this is particularly annoying because the offset forces the driller to skew on the pattern to line up with the next hole. This ruins the pattern, is bad for the tracks of the drill and slows down production due to the additional manoeuvring.

Image 2 MEC

  • Keep your naming convention consistent along the echelon.
    • Naming your holes along the echelon will help with navigation on the pattern and will improve confidence in the quality assurance of the pattern and can negate the need to number every hole on the pattern – though preference is still to number every hole for quality assurance.

Image3 MEC

  • Make your plan legible.
    • This may seem like a no-brainer, but if the people executing the plan can’t read it, it probably won’t be executed the way it was intended. May sure the font size is big enough and there is clear numbering, depths and hole angles showing on the plan. Without making the plan too busy, be sure to include any additional environment lines (bunding, faults, highwalls) which may assist the drilling. If there is a complicated stratum, include cross-sections with your plans.
  • Maintain consistency in your hole angles.
    • Where possible, keep your drill pattern simple and avoid constantly changing hole angles in your design. Changing mast angle takes time and is not good for the drill. In terms of productivity, if every second hole is a different angle, most drillers will drill out the same angle until complete, then return to the start position and do the next set of angled holes. This introduces a lot of additional manoeuvring and deadheading. It can also be a safety hazard – when drilling near a free face if the driller forgets to change back to a shallower hole angle, deeper holes can end up having significantly reduced face burdens.
  • Keep the drills drilling!
    • The drill department’s job is to manage blast-able inventory in front of the blast crew. If drilling is a bottleneck, going off path or getting into a cycle of “sprinting” benches will not achieve production goals. Remember: If a drill is walking or floating to a new pattern or re-drill, it’s not drilling. Maximising the amount of time each drill spends on a pattern will help towards improving drilled inventory. That being said, manage it properly – you don’t want to spread your drills too far apart and not complete a pattern in time or have ineffective hot seating – nor do you don’t want them stumbling over each other.
    • Increase pattern sizes – increased pattern sizes means increased production utilisation.
  • Evaluate the cost of your re-drills and the effects on production.
    • Walking a drill for 6 hours to complete a single re-drill in the middle of a production blast may not be worth it – However, a cluster of holes at the back of a pattern may be. Evaluate every re-drill with cost benefit in mind.
    • If re-drills are consistently an issue, investigate why. It may be as simple as drilling an additional 1m sub-drill on every hole because the hole is naturally backfilling.
  • Stagger your drill moves
    • As you near the end of a pattern, start walking drills off one by one – this will reduce downtime if you are waiting on a float. It will also enable you to start drilling in the new area prior to additional drills arriving so you can validate the drill bit recommendations for the area.

Effective drill management is a key skill of the Drill and Blast Engineer and is the starting place for the drill and blast design process. So, work together with your team – through better understanding of the operational process, you will significantly impact production efficiency!