One must take into account a variety of factors when selecting a drilling technique, particularly for exploration and grade control, including cost, time, environmental impact, drilling depth, and sample quality. Compared to other drilling techniques like diamond drilling or rotary air blast drilling, Reverse Circulation Drilling has many advantages. Reverse Circulation Drilling will be defined in this article along with its advantages, health and safety considerations, and reasons why it is the best method of grade control.
What is Reverse Circulation Drilling?
Reverse Circulation Drilling, or RC Drilling, is a drilling technique that makes use of dual wall drill rods, which are made up of an exterior drill rod and an inner tube. The drill cuttings may be brought back to the surface in a steady, uninterrupted flow thanks to these hollow inner tubes.
In contrast to diamond drilling, it collects sample rock cuttings rather than rock core. Most frequently, a pneumatic reciprocating piston known as a hammer serves as the drilling mechanism. It drives a drill bit made of tungsten steel that is designed to be able to crush hard rock.
Rock samples are removed with a hammer after being forced through the equipment by pressurized air. The Reverse Circulation that results from the pressure change that occurs when air is forced through the annulus of the rod's ring-shaped construction brings the cuttings up the inner tube. Cuttings are pushed through a hose connected to the top of the cyclone once they reach a deflector box at the top of the rig.
Drill cuttings will circle the cyclone before falling through the bottom hole and into a sample bag. These bags may be taken straight to the assay facility for examination and are tagged with the position and depth of the area where the sample was collected.
The advantages of Reverse Circulation Drilling
Reliable and uncontaminated samples:
Cross-contamination is avoided since the cutting does not enter other parts of the hole as it moves through the bit and into the inner tube into the cyclone. As a result, it becomes possible to produce plenty of trustworthy, high-quality samples.
Cuttings from samples are simpler to catalog and keep track of. Surveyors and other interested parties will be able to discover mineral resources more precisely since the samples gathered will contain the specific position and depth at which they were located.
High drilling penetration rates:
At larger depths, Reverse Circulation Drilling rates are frequently quicker and are equivalent to open drilling rates. The inner tube's sample velocity may reach rates of 250 m/sec, allowing the retrieval of drill cuttings a quick and safe process that requires fewer labor hours.
Production rates are higher than those of diamond drilling; at speeds more than 10 m/h, rates of 200–300 m/day are common. Consequently, RC drilling data may be disclosed to clients considerably more quickly since the drilling procedure is quicker.
Versatile in challenging environments:
Reverse Circulation Drilling is very simple and uses much less water than diamond drilling, making it excellent in countries like Australia where water may be expensive or limited. Reverse Circulation Drilling is also more economical than diamond drilling, with operational expenses down by up to 40%.
Cost savings are most obvious in geologically complex areas, where more traditional drilling techniques would result in even greater cost increases. Since Reverse Circulation Drilling is more durable in challenging situations, those expenditures will be kept to a minimum.
