Fast 2D Laser-Induced Fluorescence Spectroscopy Mapping of Rare Earth Elements in Rock Samples

Due to the rapidly increasing use of energy-efficient technologies, the need for complex materials containing rare earth elements (REEs) is steadily growing. The high demand for REEs requires the exploration of new mineral deposits of these valuable elements, as recovery by recycling is still very low. Easy-to-deploy sensor technologies featuring high sensitivity to REEs are required to overcome limitations by traditional techniques, such as X-ray fluorescence. We demonstrate the ability of laser-induced fluorescence (LIF) to detect REEs rapidly in relevant geological samples. We introduce two-dimensional LIF mapping to scan rock samples from two Namibian REE deposits and cross-validate the obtained results by employing mineral liberation analysis (MLA) and hyperspectral imaging (HSI). Technique-specific parameters, such as acquisition speed, spatial resolution, and detection limits, are discussed and compared to established analysis methods. We also focus on the attribution of REE occurrences to mineralogical features, which may be helpful for the further geological interpretation of a deposit. This study sets the basis for the development of a combined mapping sensor for HSI and 2D LIF measurements, which could be used for drill-core logging in REE exploration, as well as in recovery plants.

[1]  Jens Gutzmer,et al.  Advanced Identification and Quantification of In-Bearing Minerals by Scanning Electron Microscope-Based Image Analysis , 2017, Microscopy and Microanalysis.

[2]  J. R. Niklas,et al.  Structural point defects in “Iceland spar” calcite , 2001 .

[3]  J. Adams,et al.  THE VISIBLE REGION ABSORPTION SPECTRA OF RARE-EARTH MINERALS , 1965 .

[4]  Lawrence C. Rowan,et al.  Spectral reflectance of carbonatites and related alkalic igneous rocks; selected samples from four North American localities , 1986 .

[5]  Robert G. Eppinger,et al.  Laser-excited fluorescence of rare earth elements in fluorite: Initial observations with a laser Raman microprobe , 1992 .

[6]  Shan Qing,et al.  Development of an online X-ray fluorescence analysis system for heavy metals measurement in cement raw meal , 2016 .

[7]  David Turner,et al.  The Potential of Reflectance and Laser Induced Luminescence Spectroscopy for Near-Field Rare Earth Element Detection in Mineral Exploration , 2019, Remote. Sens..

[8]  H. Nagasawa,et al.  Rare earth concentrations in zircons and apatites and their host dacites and granites , 1970 .

[9]  Georges Boulon,et al.  Accommodation of rare-earths and manganese by apatite , 1997 .

[10]  Richard Gloaguen,et al.  Emission spectroscopy for the identification of rare earth elements using laser-induced photoluminescence , 2016, 2016 8th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS).

[11]  R. J. Elliott,et al.  CRYSTAL FIELD THEORY IN THE RARE EARTHS , 1953 .

[12]  G. S. Panayiotakis,et al.  Grains size and shape dependence of luminescence efficiency of Lu 2 O 3 :Eu thin screens , 2017 .

[13]  Jens Gutzmer,et al.  Major and trace element geochemistry of the European Kupferschiefer – an evaluation of analytical techniques , 2018, Geochemistry: Exploration, Environment, Analysis.

[14]  Georges Boulon,et al.  Laser-induced luminescence of rare-earth elements in natural fluor-apatites , 1996 .

[15]  Gus Gunn,et al.  Evidence for dissolution-reprecipitation of apatite and preferential LREE mobility in carbonatite-derived late-stage hydrothermal processes , 2016 .

[16]  B. Lüthi,et al.  Crystal field effects in rare earth systems , 1980 .

[17]  Tommi Kauppinen,et al.  Fast mineral identification using elemental LIBS technique , 2015 .

[18]  B. Pierson,et al.  The control of cathodoluminescence in dolomite by iron and manganese , 1981 .

[19]  Yadong Li,et al.  Preparation and luminescence properties of Eu3+-doped MSnO3 (M = Ca, Sr and Ba) perovskite materials , 2005 .

[20]  Teresa E. Jeffries,et al.  XENOTIME-(Y) FROM CARBONATITE DYKES AT LOFDAL, NAMIBIA: UNUSUALLY LOW LREE:HREE RATIO IN CARBONATITE, AND THE FIRST DATING OF XENOTIME OVERGROWTHS ON ZIRCON , 2008 .

[21]  A. Williams-Jones,et al.  Carbonate–silicate melt immiscibility, REE mineralising fluids, and the evolution of the Lofdal Intrusive Suite, Namibia , 2017 .

[22]  A. Williams-Jones,et al.  Hydrothermal fractionation of the rare earth elements and the genesis of the Lofdal REE deposit, Namibia , 2015 .

[23]  Nora K. Foley,et al.  Rare Earth Elements: The role of geology, exploration, and analytical geochemistry in ensuring diverse sources of supply and a globally sustainable resource , 2013 .

[24]  Bernard Jacquier,et al.  Spectroscopic properties of rare earths in optical materials , 2005 .

[25]  Gabriel M. Filippelli,et al.  The Effects of Manganese(II) And Iron(II) on the Cathodoluminescence Signal in Synthetic Apatite , 1993 .

[26]  Renata Reisfeld,et al.  Radiative and non-radiative transitions of rare-earth ions in glasses , 1975 .

[27]  Fred A. Kruse,et al.  HSI mineral mapping from airborne, outcrop, and drill-core perspectives , 2010, Defense + Commercial Sensing.

[28]  Benoit Rivard,et al.  Visible and short-wave infrared reflectance spectroscopy of REE fluorocarbonates , 2014 .

[29]  Ying Gu.  Automated Scanning Electron Microscope Based Mineral Liberation Analysis An Introduction to JKMRC/FEI Mineral Liberation Analyser , 2003 .

[30]  Rolf Fandrich,et al.  Modern SEM based mineral liberation analysis , 2007 .

[31]  R. Frietsch,et al.  Rare earth elements in apatite and magnetite in Kiruna-type iron ores and some other iron ore types , 1995 .

[32]  Renata Reisfeld,et al.  Modern Luminescence Spectroscopy of Minerals and Materials , 2005 .

[33]  Arnol'd Sergeevich Marfunin,et al.  Spectroscopy, Luminescence and Radiation Centers in Minerals , 1979 .

[34]  B. Rivard,et al.  Visible to shortwave infrared refl ectance spectroscopy of rare earth element minerals , 2015 .

[35]  Richard Gloaguen,et al.  3D Modeling of the Epembe (Namibia) Nb-Ta-P-(LREE) Carbonatite Deposit: New Insights into Geometry Related to Rare Metal Enrichment , 2018, Minerals.

[36]  Graham Ferrier,et al.  On the Feasibility of Imaging Carbonatite-Hosted Rare Earth Element Deposits Using Remote Sensing , 2016 .

[37]  Hermann Kaufmann,et al.  Hyperspectral REE (Rare Earth Element) Mapping of Outcrops - Applications for Neodymium Detection , 2015, Remote. Sens..

[38]  G. Villeneuve,et al.  Cathodoluminescence of synthetic and natural calcite: the effects of manganese and iron on orange emission , 2003 .

[39]  Lutz Nasdala,et al.  Laser-induced REE3 + photoluminescence of selected accessory minerals — An “advantageous artefact” in Raman spectroscopy , 2015 .

[40]  Richard Gloaguen,et al.  Remote Sensing Exploration of Nb-Ta-LREE-Enriched Carbonatite (Epembe/Namibia) , 2016, Remote. Sens..

[41]  M. Czaja,et al.  The luminescence properties of rare-earth ions in natural fluorite , 2012, Physics and chemistry of minerals.

[42]  Benoit Rivard,et al.  Rare earth element ore grade estimation of mineralized drill core from hyperspectral imaging spectroscopy , 2014, 2014 IEEE Geoscience and Remote Sensing Symposium.