posted by Rod McCoremick, Blog author, Fordia Powered by Epiroc
July 10, 2019
Most of our blogs focus on diamond drilling, but occasionally we will delve into topics related to geotechnical or other types of drilling. In this blog, we are going to look at reverse circulation drilling, known as RC drilling.
Fordia and Epiroc are now on the same team and our customer base has now broadened to include RC drilling customers. Let’s take a look at the two drilling methods and compare them.
RC drilling is faster
RC drilling is popular in certain parts of the world like Nevada, Australia, Latin America and Africa. When compared to diamond drilling, RC drilling will get you down to 300 meters much more quickly, saving you around two to three working days. You can then continue drilling in the harder ground underneath with a diamond drill rig.
RC drilling is cheaper
RC drilling works well in both overburden and soft, broken rock formations but its main strength is when it gets to hard composite rock. It is cost efficient due to the simplicity of the percussive drilling process and because the equipment needed is less complex. Usually, RC drilling is 25%-40 % less expensive than diamond drilling but only if the silica content in the rock is not too high.
RC drilling does not produce a core sample
The way a bore hole is drilled is completely different with RC drilling. In RC drilling, you are creating a hole in the ground as opposed to extracting a sample from the ground. At the face of the bit, everything is pulverized with RC drilling. This pulverized rock is sent up the inner tube by air pressure, exhausted to the surface in a cyclone and bagged by a helper. Not all rock cuttings are bagged. According to the geologist’s requirements, anywhere from 6% to25% of the cuttings will be used for mineralization analysis.
The pulverized rock dust or cuttings that are bagged can provide a limited amount of information about the ground. The presence of certain minerals can be detected and their location can be determined within 0.5 to1 meter of precision. Meanwhile, a core sample can show the actual veins of a mineral and their precise location in the ground which can be much more helpful to a geologist.
RC drilling information is reliable but not as accurate as core drilling
If accuracy is important, then RC drilling is not the ideal choice. It can be difficult to keep an RC drilling hole straight as they tend to corkscrew. If you need a straight pilot hole, it may be difficult to achieve using RC drilling methods.
As you can see, each type of drilling has its place depending on what you need to do. RC drilling is the way to go to if you need to drill a hole quickly and cost efficiently and if you don’t need a core sample. RC drilling is also used in a pit to do grade control for blasting purposes when selective mining is needed. It reduces the total cost of mining operations. We’ll be introducing you to new RC drilling products in upcoming blogs, so stay tuned and subscribe to our blog. If you need any additional information or guidance, you can always contact our technical support team. Their goal is to help improve your drilling performance.