SURFACE BLASTHOLE DRILLING

HOW IT WORKS?

Blast drilling is carried out to give access to blasting materials  that can be used to fragment the rocks, this enabling the removable of there material either as waste or ax ore to go through the crushing plant.

Application Used to allow the blasting chemicals to be place for blasting the rock.
Quality Important to keep alignment a depth control
Drilling speed Slow rotation speed 15 to 30 RPM, capable of between 6 – 15 M/hr
Hole depth Usually governed by mining bench depth 6 – 30 Mt
Hole size Usually between 6” and  8” Dismeter
Flexibility On Gold mines the blast hole rigs can be used to carry out grade control, this allows the mine to have an ongoing accurate levels of the mineral ore.
Cost Cost varies depending on rock hardness and the ability and cost of running the equipment.
Time Usually these rigs have a high production rate, usually giving an average of 150 to 200 metres per shift.
Technique A drill rig should be a complete system on its own wheels or tracks, this is important as there can be many activities in the mining area.

The rig should be one man operated with a fully mechanical pipe handling system.

Challenges To get to the next generation where the drill rig is computer operated.
Products & Solutions

 

Drill Structure

Blast hole drilling is so called because it is used to drill holes for blasting, the system should be fully capable of recording the drilling parameters. The rig uses either a Down Hole Hammer or a Tricone bit (Rock Bit), this depending on the rig ability and the rock strength.

Using the Down Hole Hammer, this tool is always on the rotation unit, normally with a shorter drill pipe. To set up the drill rig requires instrumentation to give the angle (if required) and direction of the hole, once set up drilling commences with proper dust controls in place, or if sampling for grade quality, the system of retrieving the sample is operating correctly, again with dust controls in place.

As the hole progresses, drill pipe from the carrousel (or similar device) are added until hole depth is achieved.

There are two methods of drilling:

  1. Blast-hole drilling using compressed air with a Down Hole Hammer.
  2. Blast-hole drilling using compressed air with a trigone bit (rock bit)

Of the two methods a. is the most favoured method, however it depends on the running cost which can be dependant on the following:

Cost of personnel

Cost of the equipment over its life

Cost of fuel for the rig & compressor