Laser-induced breakdown spectroscopy (LIBS) is a rapid chemical element analysis technique, developed since the invention of the laser in 1960.
A focused laser pulse strikes the sample surface and ablates an amount of material to generate a high-temperature plasma plume. Atoms and ions are excited to higher energy levels and while returning into their ground state, emit characteristic energy signatures for each element.
LIBS is used in a variety of applications including analysis of soil, effluents, scrap metal, alloy and molten metals. LIBS is the same technology on which the ChemCam on NASA's Mars Rover is based.
According to CRC ORE, the robustness of LIBS is well suited for real-time mineralogy analysis and at all stages of the mining production cycle. Commercially available laboratory-based Quantitative Mineral Analysers (QMA) such as QEMSCAN and MLA have historically been commonly used in the mining industry. However, these technologies are not suited for in-stream or on-belt applications due to their meticulous sample preparation and measurement protocols. Conversely, LIBS has the potential to provide on-line QMA in real time.
While the decades old LIBS technology remains at the forefront of fast chemical element analysis it is still limited to costly laboratory-based sampling. This requires the extraction of extensive samples and the transport of these to lab facilities, sometimes many hundreds of kilometres away from the mine site.
CRC ORE is working with NRC Canada to deliver real time onsite mineral analysis. Its planned applications include mineral characterisation across a conveyor belt; additionally, the use of LIBS is being examined as an industrialised elemental and mineralogical analyser for scanning coarse rock streams.
Dr Greg Wilkie, CRC ORE program coordinator, said that the two organisations are taking LIBS use in the mining industry to the next level by putting the technique to use in operating mine sites.
He commented: "By applying LIBS in a real time application such as across an operating conveyor belt, operators are empowered with high volumes of rapid analysis provided in real time. Analysis in real time speeds up the mineralogy process, providing operators with detail they may have previously had to wait days or weeks to obtain.
"We are proudly putting the mineralogy back into process mineralogy."
Dr Alain Blouin, senior research officer at NRC Canada, said that the council and CRC ORE are working on a long-term LIBS project which is nearing the end of an intensive two-year study.
He explained: "We are developing a novel application of a LIBS rapid on-line mineralogical characterisation instrument suitable for deployment on mine sites. LIBS can measure a large number of elements simultaneously with the ability to detect light elements beyond the capability of many other techniques."
Dr Wilkie noted that since LIBS can perform analysis several metres away from what it is measuring and still detect extremely low concentrations, it makes it well suited technology for the mining industry. He added: "Beyond cross-belt scanning, LIBS can work in a variety of settings from in-pit muck piles, underground draw points and on-line slurries."
It is anticipated that the real time LIBS solution be used in conjunction with CRC ORE's Grade Engineering, its approach to the early separation of ore from waste material. CRC ORE stated that Grade Engineering is minimising the impact of declining grades and productivity in the Australian and global minerals sector.
