Reverse-circulation drilling

Reverse circulation drilling is similar to air core drilling as the samples that are drilled up from the earth are not simply placed onto the surface surrounding the machine but the samples are instead shot up into the hollow pipe of the machine. This is one of the biggest benefits of the reverse circulation drilling procedure because it prevents the samples from being contaminated from other materials that it might come into contact with once it has been removed from the earth.

The reverse circulation drilling method has the capability of reaching depths of 500 metres. A pneumatic hammer-like device is used to hammer into the earth to remove rock samples which are then pushed up into the mining machine using compressed air. The samples are collected in a sample bag which is located within the machine. More than one sample bag can be collected which allows for more of a variety of samples to be analysed. Sample bags are usually marked to show the location from which the sample was taken as well as the depth from which the samples are extracted.

The drill bit used is created out of tungsten steel which means that it is able to crush hard rock. The reverse circulation drilling machine is larger than most of the exploratory machines in the industry and that adds to the cost of running such a machine. The costs of using this procedure can be higher than the other techniques but the benefits of accurate, non-contaminated samples and being able to get samples from greater depths than most of the other drilling machines are capable of reaching makes using reverse circulation drilling worth the costs.

What are the advantages and disadvantages of reverse circulation drilling?


  1. Although the process can be costly the overall drilling costs can actually be reduced by up to 40% when using reverse circulation drilling.
  2. Results from reverse circulation drilling can be revealed much faster as the completion of the drilling process is done quickly.
  3. The method is safe to use and requires fewer man hours.
  4. Reverse circulation drilling requires less water than other mining methods.
  5. Reverse circulation drilling is simple and easy.
  6. Samples can be easily arranged into boxes stating where the sample was collected and at what depth the sample was collected which will help those studying the samples to pinpoint exactly where the mineral deposit is located. This will help a mining company or a group of researchers to quickly and easily locate the exact area and depth from which the sample was discovered.


  1. The samples produced from reverse circulation drilling can have less geological relevance.
  2. The holes created from reverse circulation drilling are susceptible to movement if not properly stabilised especially as holes can reach depths of up to 500 metres.
  3. Other methods can be used to drill deeper however reverse circulation drilling has been known to reach depths of up to 800 metres.

Master Drilling offers reverse circulation drilling solutions worldwide with preference to the following countries: Peru, Chili, Brazil, Colombia, Ecuador, Argentina, Bolivia, Guatemala, United States of America, Canada, Mexico, Honduras, Nicaragua, China, India, Vietnam, Indonesia, Philippines, Russia, Kazakhstan, Australia, Papua New Guinea, Ghana, Zambia, Mozambique, Namibia, Botswana, Tanzania, DRC, Mali, Burkina Faso, Saudi Arabia, Zimbabwe, Kenia, Namibia , South Africa, Ireland, Poland, Finland,  Sweden, Norwegian, Portugal, Italy, Bulgaria, Turkey and Malta.