Abstract
Geochemical characterization including mineralogical measurements and kinetic testing was completed on samples from the Montviel carbonatite deposit, located in Quebec (Canada). Three main lithological units representing both waste and ore grades were sampled from drill core. A rare earth element (REE) concentrate was produced through a combination of gravity and magnetic separation. All samples were characterized using different mineralogical techniques (i.e., quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), X-ray diffraction (XRD), and scanning electron microscopy with X-ray microanalysis (SEM-EDS)) in order to quantify modal mineralogy, liberation, REE deportment and composition of REE-bearing phases. The REE concentrate was then submitted for kinetic testing (weathering cell) in order to investigate the REE leaching potential. The mineralogical results indicate that: (i) the main REE-bearing minerals in all samples are burbankite, kukharenkoite-Ce, monazite, and apatite; (ii) the samples are dominated by REE-free carbonates (i.e., calcite, ankerite, and siderite); and (iii) LREE is more abundant than HREE. Grades of REE minerals, sulfides and oxides are richer in the concentrate than in the host lithologies. The geochemical test results show that low concentrations of light REE are leached under kinetic testing conditions (8.8–139.6 µg/L total light REE). These results are explained by a low reactivity of the REE-bearing carbonates in the kinetic testing conditions, low amounts of REE in solids, and by precipitation of secondary REE minerals.
Highlights
These elements are often classified into two main categories: light (LREE, La to Gd) and heavy (HREE, Tb to Lu) rare earth elements
Fine grinding of the FeC-HG was required to ensure a high recovery of REE-bearing minerals to the REE concentrate
Three lithological units chosen from exploration dill core to represent the heterogeneity of the GéoMéga waste rocks and a REE concentrate were tested
Summary
Rare earth elements (REE), called lanthanides (La to Lu, Sc, and Y), have been considered strategic metals, as they are a key component in the manufacturing of modern technologies. Their economic importance has grown as a result of their use in a wide range of industries including the manufacturing of products aimed at environmental conservation and sustainability. These elements are often classified into two main categories: light (LREE, La to Gd) and heavy (HREE, Tb to Lu) rare earth elements. China produces 99% of HREE and 87% of LREE [1]
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