Heritage Minerals Smash Terrier Percussive Depth Record
A team, led by drilling manager Shane Charlton, have been achieving depths of 46m with high quality 86mm samples.
Heritage Minerals operate at the historied Mt. Morgan mine in Queensland, Australia. One of Australia’s oldest mines, Mt. Morgan was active from 1882 through to the 1980s. In the process tens of millions of tonnes of tailings were generated.
Today these tailings present both a problem and an opportunity. A problem because they were subject to old, polluting technologies for processing gold, but an opportunity because they still contain untold reserves of gold, copper and other minerals.
Heritage Minerals employ innovative processing technologies, developed by partner Green Gold Technology, to clean pollutants from the tailings and returning them to safe land. The same technology is also able to reprocess the material to retrieve the target metals efficiently.
Dando Terrier for Top Recovery in Difficult Formations
Heritage chose a Dando Terrier rig to sample the tailings for a number of reasons. Foremost, the unconsolidated geology of tailing fines is very hard to sample with conventional rotary equipment. The Terrier’s Duplex Sampling System, which is driven into the ground by a 64kg anvil and simultaneously cases-off and samples, provides excellent recovery in this type of unconsolidated
geology for metallurgical and in situ density measurements.
Charlton proved and refined the drilling method he uses in the mineral sands of Kalimantan, Indonesia, where he sampled alluvials to over 20m for lab analysis. An impressive feat for a rig that has a large userbase for geotechnical sampling, standard penetration testing and dynamic probe testing, most often at depths less than 15m.
More than doubling this to 45m was no easy task, explains Charlton: “At depth it took almost 10 minutes to trip the drive rods and retrieve the sample”, he says, “but the quality of the sample and the economies in terms of cost per metre offset the sometimes slow drilling.”
Heritage Minerals have recently purchased a second Terrier rig from a Dando customer in Australia and Charlton has made some modifications to the design to facilitate drilling beyond the original specs of the little rig: “We’ve fitted a permanent casing extractor to help pull sample tubes and casing if they get stuck”, he explains, “as well as modifications to assist with tripping rods more quickly.”
In order to achieve these depths, the team are using a reaming method whereby they sample using an 86mm windowless sampler tube, and then ream out using a larger 116mm tube before returning to the 86mm sampler to continue. This reduces frictional forces along the side of the borehole and abrasive tailing materials.
The percussive hammer system allows sampling without flush, minimising the need for cumbersome mud tanks or air compressors while preventing contamination of the sample or the environment.
Please visit the Heritage Minerals website website for more information about their operation and technologies such as ReCYN technology that they are employing to clean up the environment and reprocess the tailings at the site.