Abstract
The global demand for rare earth elements (REEs) is expected to increase significantly because of their importance in renewable energy and clean storage technologies, which are critical for drastic carbon dioxide emission reduction to achieve a carbon-neutral society. REE ore deposits around the world are scarce and those that have been identified but remain unexploited need to be developed to supply future demands. In this study, the Khalzan Buregtei deposit located in western Mongolia was studied with the aim of upgrading low-grade REE ore via magnetic separation techniques. The total REE content in this ore was ~6720 ppm (~3540 ppm light REE (LREE) + ~3180 ppm heavy REE (HREE)) with bastnaesite, pyrochlore, synchysite, and columbite-(Fe) identified as the main REE-bearing minerals. As the particle size fraction decreased from −4.0 + 2.0 mm to −0.5 + 0.1 mm, the recovery by dry high-intensity magnetic separation (DHIMS) increased from 20% to 70% of total rare earth oxide (TREO) while the enrichment ratio reached 2.8 from 1.3. Although effective, gangue minerals such as quartz and aluminosilicates were recovered (~22%) due most likely to insufficient liberation. Meanwhile, the wet high-intensity magnetic separation (WHIMS) could produce a magnetic concentrate with TREO recovery of ~80% and enrichment ratio of 5.5 under the following conditions: particle size fraction, −106 + 75 μm; feed flow rate, 3.2 L/min; magnetic induction, 0.8 T. These results indicate that combining DHIMS and WHIMS to upgrade the low-grade REE ore from the Khalzan Buregtei deposit is an effective approach.
Highlights
Climate change is one of the most important and urgent issues faced by humanity this century that needs a solution [1,2,3]
Among the materials for low-carbon technologies, rare earth elements (REEs)—a group of 17 elements consisting of lanthanides (lanthanum (La) to lutetium (Lu)) as well as scandium (Sc) and yttrium (Y)—are of great importance because significant quantities of REEs are utilized for manufacturing strong permanent magnet, a critical component used in generators for wind turbines and traction motors for electric vehicles (EVs) [8,10,11,12]
Between gravity and magnetic separation techniques, the former is less attractive for processing low-grade and fine-grained ores [16]; this study aimed to investigate the applicability of dry/wet magnetic separation techniques for upgrading low-grade rare earth ore from the Khalzan Buregtei deposit
Summary
Climate change is one of the most important and urgent issues faced by humanity this century that needs a solution [1,2,3]. The global mean temperature for 2020 was approximately 1.2 ± 0.1 ◦ C warmer than pre-industrial levels (i.e., the period 1850–1900). In 2015, the Paris Agreement was adopted by the 196 parties with the aim of limiting the global temperature rise to “well below 2 ◦ C”, preferably to. In accordance with the Paris Agreement, 193 governments adopted the 17 sustainable development goals (SDGs), Goal 13 of which is “Climate Action” aiming at reducing CO2 emission to combat climate change and achieve a carbon-neutral society by 2050 [6,7]. Low-carbon technologies are more intensive towards material, mineral and metal rather than conventional fossil-fuel-based technologies [7,8]. The stable supply of REEs for the 20–30 years is important in the success of transitioning into a carbon-neutral society
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