No abstract

Geochemical and mineralogical characterization studies play an important role in the definition of mineral deposits. Each mineral system has a unique set of minerals with different chemical makeup and physical properties. Platinum-group elements (PGEs), for example, are scarce resources with many applications. The optimization of extraction process efficiency is therefore crucial to prevent resource shortage and increased bulk prices. To improve the mineral liberation process, high throughput sensors must be added alongside the production line as part of fast process analysis implementation. Current analytical methods are either ineffective to assess PGE content, or unusable in the conditions of the processing facilities. This article shows how Laser-induced breakdown spectroscopy (LIBS) technology, developed by ELEMISSION Inc, can circumvent these drawbacks by enabling automated, ultra-fast, and precise quantitative mineral analyses in any working environment. The drill core samples that were used in this study were collected at the Stillwater platinum group element mine in the United States. The data used for the mineralogical database was validated using the TESCAN Integrated Mineral Analyzer (TIMA) instrument.

Standard techniques for geochemical and mineralogical characterisation are time-consuming, they can involve significant sample preparation and they are prone to error. The aim of this work is to show how the emerging fast laser-induced breakdown spectroscopy (LIBS) technique can be valuable for mineral exploration. For this purpose, the well-established micro-X-ray fluorescence (µ-XRF) technique was used to validate the LIBS data. Two ore samples from the platinum-group elements (PGE) Lac desÎles mine (Ontario, Canada) were analysed both by LIBS and µ-XRF. The fast mineralogical and elemental mapping provided by LIBS allowed the identification of four major silicate phases (chlorite, bytownite, actinolite, hornblende) and four minor sulfide phases (Pd-bearing pentlandite, chalcopyrite, pyrrhotite, pyrite). Multi-element chemical mapping and mineral characterisation using µ-XRF corroborated the LIBS analyses for the composition, distribution and abundance of minerals in PGE ore samples. These findings demonstrate the ability of the LIBS technique to perform direct fast high-resolution mapping of the chemical and mineralogical composition of PGE ore samples. This work highlights the advantages of LIBS for this application of being much faster and more sensitive to trace elements (e.g., Pd), as well as to low atomic number elements.

This article reports on the quantification of lithium and mineralogical mapping in crushed lithium ore by laser-induced breakdown spectroscopy (LIBS) using two different calibration methods. Thirty crushed ore samples from a pegmatite lithium deposit were used in this study. Representative samples containing the abundant minerals were taken from these crushed ores and mixed with resin to make polished disks. These disks were first analyzed by TIMA (TESCAN Integrated Mineral Analyzer) and then by a LIBS ECORE analyzer to determine the minerals. Afterwards, each of the thirty crushed ore samples (<10 mm) were poured into rectangular containers and analyzed by the ECORE analyzer, then mineral mapping was produced on the scanned surfaces using the mineral library established on the polished sections. For the first method the lithium concentrations were inferred from the empirical mineral chemistry formula, whereas the second one consisted of building a conventional calibration curve with the crushed material to predict the lithium concentration in unknown crushed materials.

Scarce platinum group elements (PGE) are mainly concealed in massive sulfides, and finding economically viable ore bodies largely relies on their fast chemical mapping. Most core scanners provide incomplete mineralogical contents, but none also provide a complete chemical analysis including light elements. This study investigates the performance of a fully automated laser-induced breakdown spectroscopy (LIBS) core scanner, the ECORE, by comparing its reliability to a scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) mineral mapper and its speed to infrared diffuse reflectance hyperspectral imagers (IR-HSI). The LIBS elemental imaging has been put to the test in our previous work, as well as the high-resolution mineralogical mapping. This paper reports the scaling up analytical applicability of LIBS as a high performance and high-speed drill core scanner. The analysis of a full core tray in this study is the first and largest 7.62 megapixels image done by a LIBS core scanner to our knowledge. Both high-resolution and low-resolution data are put together to express both mineralogical and chemical content as a function of depth.