reverse circulation drilling

What is Reverse Circulation (RC) Drilling? [Inc. Video]

Reverse circulation (or RC as it’s more commonly known) drilling is an essential tool in the mining industry. In addition to other oil rigs and drill rigs, reverse circulation drills assist in the productivity and accuracy in mining jobs.

RC drilling is a drilling method involving a large rotary drill and air compressor that yields high quality mineral and rock samples, free from contamination and material interference.

It is the preferred method of mineral exploration, drilling and in-pit grade control because it is fast and cost-effective.

What is RC Drilling?

Much like air core drilling, RC drilling returns cutting to the surface through an inner tube inside the rod. This is achieved by blowing air down the rods at a rate up to 1500 Pascals. This creates a pressure differential that pushes cuttings and water up via air lift.

The drilling component is powered by a pneumatic reciprocating piston (also known as the hammer), which drives a steel drill bit.

The two most commonly used drilling bits in RC systems are the fixed cutter and roller cone, both of which are advantageous depending on the project and geographical location of the site.

RC drilling is primarily used on large machinery and drill rigs and often goes to depths of 500 metres. [Source]

High quality RC equipment also has the ability to dry out the rock with large air compressors before the drill hits, which provides dry rock chips and, in turn, better samples.

History of Reverse Circulation Drilling

Grade control rig

The innovation behind RC drilling is proudly Western Australian.  During the middle of the last century, drilling in soft iron ore and mineral sands using the traditional open hole techniques was proving to be difficult. Due to this need, Bruce Metzke and John Humphries of Kalgoorlie created the first RC drill rods in 1972 [source].

As the years pass, the need for cleaner samples increased, which led to the development of the RC hammer in 1990. Around the same time, high pressure boosters and auxiliary were added to penetrate faster and to create deeper holes.

The introduction of this technology made RC drilling the most cost effective and accurate method available, particularly in an era where mining costs were rising.


In Western Australia, reverse circulation drilling is the predominant technique based on a number of advantages.

  • A higher percentage of uncontaminated cuttings
  • Drilling rate similar to open hole drilling, but can often be faster and penetrate greater depths
  • One of the most accurate drilling methods
  • Quick retrieval of sample rates
  • Dry samples allow for easier analysis

Reverse circulation drilling has earned a reputation for good results in the mining industry because of its ability to attain high quality samples and its cost effectiveness.  If you are after RC drilling machinery for your next project, please contact us for further assistance.