ADVANCED FLOTATION STRATEGIES TOWARDS ECO-EFFICIENT RARE EARTH ELEMENTS ORE BENEFICIATION M.C. Vila1, M.L. Dinis1, F. K.A. Frutuoso1, A.C. Silva1, A. Magane1, E. Levei2, I. Török2, N. Gajendra3, L. Ferrando-Climent3 1CERENA, Faculty of Engineering, University of Porto, Portugal *mvila@fe.up.pt 2National Institute of Research and Development for Optoelectronics, INOE 2000, Research Institute for Analytical Instrumentation Subsidiary, Cluj-Napoca, Romania 3Department of Tracer Technology Kjeller, Institute for Energy Technology, Environmental Technology Section, Norway ABSTRACT Rare earth elements (REEs) are critical raw materials with extensive industrial applications; however, their beneficiation remains challenging due to the complex metallogeny of REE-bearing ores. In this context, this study—conducted within the framework of the Horizon Europe project REESource—aimed to evaluate the performance of environmentally friendly depressants in the flotation of REEs from the Fen Deposit, Norway. Drill core samples, consisting of an iron–dolomite–carbonatite ore hosting bastnäsite, parisite, synchysite, and monazite, were subjected to laboratory-scale grinding and direct flotation following a two-stage conditioning route under heated pulp. Flotation tests were performed using quinic acid, phytic acid, sodium alginate, and citric acid as depressants, and flotation performance was assessed through pH, oxidation– reduction potential, and temperature monitoring. Feed and flotation products were characterized by X-ray fluorescence and inductively coupled plasma mass spectrometry. The results showed that the depressant dosages applied were insufficient to achieve effective gangue rejection. Sodium alginate exhibited the highest potential for depressing magnesium- and barium-bearing gangue phases, whereas quinic acid yielded the highest REE recoveries, albeit with limited selectivity. Overall, the findings emphasize the importance of depressant selection and dosage optimization to improve flotation selectivity and support the development of sustainable beneficiation routes for carbonatite-hosted REE ores. KEYWORDS Rare earth elements; Sustainable mineral processing; Flotation reagents; Fen deposit. 1. INTRODUTION Rare earth elements (REEs) are critical raw materials widely used in advanced technologies, including electronics, electric vehicles, renewable energy systems, aerospace applications, and high-performance magnets. In Europe, the transition toward a low-carbon energy system has significantly increased the demand for REEs, highlighting the need for secure and
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