Reverse Circulation Drilling Rigs

About the FYRC reverse circulation rigs

The FYRC range is a crawler-mounted reverse circulation family. Instead of recovering a core, an RC rig returns the rock as a continuous stream of cuttings, which is what makes it the standard tool for grade control on a producing mine: the sample covers the whole hole, it arrives while drilling, and the rig spends almost no time tripping rods. These machines carry the torque and the rod-handling hardware that deep RC work demands. The automatic rod changer on the larger models was developed with Central South University, and the rotary sample splitter is integrated on the rig rather than bolted on afterwards.

Typical applications

• Mine grade control — Infill sampling on production benches to fix the ore and waste boundary before the blast pattern is loaded.
• Resource definition drilling — Stepping out from known mineralisation to establish continuity and grade between cored holes.
• Blasthole sampling — Recovering a sample from the blasthole itself, so the assay and the blast design come from the same hole.
• Reconnaissance and first-pass exploration — Fast, low-cost coverage of a new prospect before committing to a diamond core programme.
• Quarry and industrial mineral control — Checking limestone, aggregate and industrial mineral quality across a deposit as it is worked.

How it works

An RC rig drills with dual-wall rods. Compressed air travels down the annulus between the outer and the inner tube, crosses over at the bit, and carries the cuttings back up the centre of the inner tube. The sample never touches the borehole wall on its way out, which is why cross-contamination between successive metres stays low, and it arrives continuously instead of one core run per trip. At surface the return passes through a cyclone and a rotary splitter, which divides the stream into a reference sample and an assay sample at a fixed ratio.

• Air does the lifting, so the compressor is half the drilling system: pressure and free air delivery decide how deep the rig can keep the hole clean.
• The inner tube has to stay sealed from the annulus. A worn crossover sub or a damaged inner tube shows up first as a contaminated sample, not as a drop in penetration rate.
• Automatic rod handling is not a comfort feature on deep holes. It removes the manual handling behind most rod injuries and shortens every rod change.
• Sample quality depends on the splitter as much as on the rig. A splitter that is not cleaned between holes carries contamination forward.

How to specify the right model

RC selection starts with the sample, not the machine. Decide the hole diameter your assay programme needs, the depth at which you need reliable returns, and the sample volume the splitter has to deliver.

• Hole diameter in RC work is usually set by sample volume rather than by ground conditions, because a larger hole returns more sample per metre.
• Depth capability is limited by air pressure and by back-pressure in the rod string, so check the air package against the deepest hole on the programme, not the average.
• Confirm the rod diameter and thread series. RC rods are not interchangeable between systems, and the rig has to match the string you will actually buy.
• Where the rig has to climb benches or work on soft ground, check the crawler and the ground pressure before the headline specifications.
• Ask how the splitter is cleaned and how the reference sample is stored. That is what an audit of the assay programme will look at.