Sensor developments through the Deep Exploration Technologies Cooperative Research Centre are enabling fast onsite analysis of a range of elements and minerals, helping explorers more cost-effectively navigate greenfields exploration. TIM THWAITES reports
Lab-at-Rig advances increase analytical capabilities at the drill site
A new sensor that expands the range of elements and minerals that can be detected and assessed, as well as faster, automatic analysis software, are being added to the Lab-at-Rig technology.
By bringing the laboratory to the drill site, Lab-at-Rig allows companies to make multi-million dollar decisions in minutes rather than months.
The technology has been developed for mineral exploration by a CSIRO-led research team in the Deep Exploration Technologies Cooperative Research Centre (DET CRC).
The latest advances increase the technology’s capacity to provide practical information to geologists and drillers in real time. They also bring Lab-at-Rig closer to playing a significant role in both the DET CRC and CSIRO strategies for efficient, cost-effective exploration for mineral resources underneath surface cover – the blanket of deeply weathered rocks and transported sediments that covers about 80 per cent of Australia.
Drillhole data in real time
“The major advantage of Lab-at-Rig is that it obtains data on minerals in real time from a hole you are drilling,” DET CRC’s CEO, Richard Hillis, says.
“That might lead you to continue a hole you would otherwise terminate if there are encouraging results. It might also permit you to drill a follow-up hole without waiting for lab analysis and expensive demobilisation and remobilisation of the drill rig and crew.”
Lab-at-Rig was initially developed for diamond drilling by a research team led by CSIRO principal research scientist, Dr Yulia Uvarova. It is designed to analyse the chemistry and mineralogy of rock chips or cuttings brought directly up from bit to surface in the constant stream of drilling fluids. The exact location of the chips can be calculated from the depth of the bit and the speed of fluid flow.
The rock particles are then dewatered, dried, packed and analysed using x-ray sensors. The first two sensing technologies used for this purpose – in collaboration with imaging company Olympus and mining technology company Imdex – were x-ray fluorescence (XRF) spectrometry and x-ray diffraction (XRD).
Lab-at-Rig has been licensed by REFLEX, a subsidiary of Imdex, and has been involved in numerous extended trials, including in the USA. The sensors provide accurate concentrations, as well as mineral abundancies, of elements such as copper, iron, zinc and silver out in the field, a process that could otherwise take months in a laboratory and cost hundreds of dollars a sample.
“These x-ray sensors do not deliver accurate concentrations for gold and rare earths, and can’t be used to detect elements lighter than magnesium, such as sodium and carbon, which are important to geologists,” Dr Uvarova says.
Laser-induced breakdown spectroscopy sensor upgrade
To address this gap, Dr Uvarova’s team is working on a third sensor based on laser-induced breakdown spectroscopy (LIBS).
Until now, this technology had been more of a laboratory research tool for the analysis of pharmaceuticals, alloys and other non-geologic materials. However, there have already been encouraging results from prototypes developed for Lab-at-Rig with the help of technical and user advice from the CRC’s partners.
Dr Uvarova’s team is also working on what it calls a fluid management system – an ability to analyse the drilling fluids using ion-selective electrodes. This can provide information to drillers on pH, temperature and conductivity – for protecting equipment – and also on concentrations of ions such as calcium, chloride and sulfide that are used in geological interpretation.
Adopting techniques from petroleum exploration
All these facets of Lab-at-Rig are in the process of being recast to fit in with coiled-tubing (CT) drilling, a technology from the petroleum industry that the CRC has modified for mineral exploration. Instead of the standard, three-metre rods used in diamond drilling, a continuous coil of 500 metres of tubing is used. The tubing is carried on a light (15-tonne) mobile drilling rig mounted on caterpillar tracks that can easily be transported on a low loader. Drilling with a continuous coil removes the need to connect and disconnect drill rods, making it faster, cheaper and safer than conventional drilling.
The CT technology can drill about half a dozen holes for the same cost as one conventional diamond hole. With the mobility and relatively simple set-up of the new lightweight rig and using Lab-at-Rig’s real-time data, it will be possible to undertake an exploration program of drilling multiple holes that progressively vector towards mineral deposits.
The rapid speed of CT drilling makes the new software critical.
“SwiftMin, the new software for processing of XRD data, for instance, replaces time-consuming laboratory analysis,” Prof Hillis says.
“That’s critical because the new CT drilling should be covering about 50 centimetres a minute. Therefore if you want metre-by-metre analysis down the hole, you need an XRD reading and analysis every two minutes – and that’s a huge challenge. Such automated processing of XRD data is critical for Lab-at-Rig to keep up with the rapid, cheap drilling we’re doing.”
The CT drilling technology has just been offered to DET CRC’s supplier participants Boart Longyear and Imdex for commercialisation.