What is the RAB hole and RC hole in terms of mining?

Question

cheers, guys, looking for the best answer

Answer 1

RAB - rotary air blast

RC - reverse circulation

RAB drilling uses a rotary bit with the hammer on the drill chuck.  Compressed air is blown down the middle of the drill string, with cuttings blown up the outside of the drill string. The cuttings are subject to contamination from other rocks in the hole, so that your sample is not only from the cutting bit.  But its quick and cheap.

RC drilling uses double-walled drill pipe attached to a down-hole hammer.  Compressed air is blown down the outer pipe chamber, and the the cuttings are blown up the center of the drill pipe, so that the cuttings are not contaminated.  RC rigs have the additional advantage of being able to drill deeper than RAB - 100's of meters instead of 10's of meters.

http://www.midnightsundrilling.com/rever...