A portable LIBS analyzer for in-situ measurement of low gold grade in ore

2019

Paul Bouchard, National Research Council Canada; Christian Padioleau, National Research Council Canada; Mohamad Sabsabi, National Research Council Canada; Alain Blouin, National Research Council Canada; Francis Boismenu, National Research Council Canada; André Beauchesne, National Research Council Canada

The assessment of gold grade in mineral ore at different stages of the mining value chain is a key element of the global gold mining exploitation process.  Mining operators would definitely benefit from a quick and accurate method that would allow the in-situ determination of gold concentration in several locations in the mine, such as on the surface of tunnel walls, or directly in ore samples, such as chips or muck piles. Laser-induced breakdown spectroscopy (LIBS) is presently emerging as a technique with great potential for performing elemental analyses in such harsh conditions. LIBS appears as a good candidate for the quantitative assessment of gold content in the ore. The technique provides a direct measurement of gold concentration at the part-per-million level instead of relying on gold tracers. However, the development of a functional LIBS-based portable device faces several challenges: it should feature a high spectral sensitivity and resolution, allow adequate sampling of the surface of the mineral samples and show a high level of robustness and stability, to name only a few. In this presentation, we introduce and describe a breakthrough functional portable LIBS gold analyzer designed for in-situ measurements, which has been developed in a multi-party agreement involving partners from the Canadian gold mining industry. In addition, its performance in terms of sensitivity and limits of detection is discussed.  Results of measurements performed on mineral samples are shown and a comparison with lab analysis measurements is discussed with focus on gold in mineral ore samples. The device has been tested underground in gold mines.

Keywords: Gold grade, Laser-Induced Breakdown Spectroscopy, mineral samples