RAB Drilling for Mining Explained

The mining industry being quite popular here in Australia, we wanted to give you guys a heads up on this industry by focusing on a popular sub niche of this market which is drilling.

Percussion Rotary Air Blast (RAB) Drill

RAB Mine Drilling which is different from air core drilling techniques.

Matching a drilling rig for a particular type of mining job is not a simple task. There are many factors to consider, such as the terrain, quality of samples required for analysis, depth, cost, time, fuel and attendant equipment.

miner drilling the groundThere are several factors when looking at drilling rigs in general:

* the type of power used – mechanical, electric, hydraulic, pneumatic, steam
* type of pipe used – cable, conventional, coil tubing
* by how many connected pipes they can stand in the derrick
* method or rotation or drilling method – no-rotation, rotary table, top drive, sonic, hammer
* position of derrick – conventional, slant

If you are looking for a simple drill for a simple job it is is not quite so difficult. If you are looking for an economical, fast, single-pass exploration drill, then an RAB drill is probably what you need.

Blast hole drilling should also be a simple requirement, and again, an RAB drill is the fastest, most economical machine for this type of task.

Mining Drilling Rigs

Mining drilling rigs are used for two primary purposes:

* Exploration drilling, which aims to identify the location and quality of a mineral; and
* Production drilling, used in the production cycle for mining.

Mineral exploration drilling is conducted as part of an advanced research program to obtain detailed information about the rocks and minerals below the ground surface. The drilling method and size of the drilling rig used depend on upon the type of rock, the depth required, and level of information sought.

The most common shallow depth mineral exploration drilling method is Percussion Rotary Air Blast (RAB) drilling. This type of operation is the quickest method, can be very mobile, can access steep terrain, and usually only requires one operator.

Mine production drilling, particularly open cut mining, includes blast hole drilling, and a conventional method is RAB drilling. A large RAB drilling machine can drill hundreds of holes a day, up to hundreds of metres deep. As a self-contained machine, operating on pre-prepared terrain, they run on crawling tracks for mobility, but they still managed by a single operator.

What is an RAB Drill?

60 inch concrete core drillA Percussion Rotary Air Blast (RAB) drill is a down-the-hole vertical drill which uses a pneumatic reciprocating piston-driven hammer action to energetically drive a heavy drill bit into the rock.

Drill bits are hollow, solid steel and have 20 mm thick tungsten rods protruding from the steel matrix as “buttons”. The tungsten buttons are the cutting face of the bit.

Compressed air is pumped through a hole in the rod and the drill bit, forcing the cuttings to the surface between the drill pipe and the wall of the hole.

RAB drilling can achieve depths of more than 50 metres but can be ineffective below the water table, where the annulus between the drill pipe and the surrounding formation can become clogged with debris, precluding removal of drill cuttings from the hole. This can be overcome by the use of stabilisers (also known as reamers), which are lengths of tubular steel attached to the drill string to ream or line the hole to prevent formation water and debris entering the hole. Stabilisers commonly have tungsten-buttons on the walls to break down the cuttings rising from the borehole.

Machine Size

RAB rigs range in size from a small truck or trailer mounted machines that can be used in hard-to-access areas, or for smaller operations. The larger models are an all-in-one and are mounted on caterpillar tracks for movement, but are restricted to specially prepared flat surfaces. Whatever the size, the method of operation is the same. It is simply a matter of scale.

Penetration Depth

Depending on its size and drill bit, RAB rigs can penetrate depths up to 100 metres. It penetrates quickly and easily through almost every type of rock. Because of its fast operation, this makes an RAB drill an excellent choice for blast hole drilling.

Operational Cost

Compared to RC and Diamond drilling, RAB drilling is quickest and more economical and only requires one operator.

Mineral Analysis

The cutting debris can be used for low-level mineral analysis. As a first-pass method in mineral exploration, this approach produces results faster, cheaper and easier.

Considering the array of mining tools required and available on the market, the Percussion Rotary Air Blast drill is one of the simplest, but that does not make it insubstantial.

So, Why an RAB Drill?

RAB rigs can be small – mounted on the back of a truck, making it very mobile and able to access steep terrain. They can also be enormous, require a crawler track to move around.

The depth of drill hole is a factor to consider when deciding on a drilling machine, but if you are looking at shallow depths (up to 100 metres), then an RAB drill is a good one to watch for economy and speed.

See these bad boys in action:

Ressources:

Australian Government

Wikipedia

Bostech Drilling