How Does It Work?
Reverse circulation drilling (RC) is a method of drilling mechanism is a pneumatic reciprocating piston known as a “hammer” driving a tungsten-steel drill bit. RC drilling utilises much larger rigs , compressors and boosters and depths of up to 500 metres. RC drilling ideally produces dry rock chips, as large air compressors dry the rock out ahead of the advancing drill bit. RC drilling is cheaper than diamond coring and is thus preferred for most mineral exploration work.
Reverse circulation is achieved by blowing air down the rods, the differential pressure creating air lift of the water and cuttings up the inner tube, which is inside each rod. It reaches the deflector box at the top of the rod string then moves through a sample hose which is attached to the top of the cyclone. The drill cuttings travel around the inside of the cyclone until they fall through an opening at the bottom and are collected in a sample bag. For any drill hole there will be a large number of sample bags, each one marked to record the location and drilling depth that the sample was obtained.