Produção de concentrado de terras raras do rejeito da flotação de nióbio

Abstract

Rare earth elements (REEs) are essential for the global economy due to their applications in technological products, their role in the energy transition, and their contribution to a more sustainable energy matrix. Currently, China holds the largest reserves and production of these elements, but aiming to protect its resources and promote the growth of its industry, these elements have consolidated as critical and strategic inputs, stimulating other countries, including Brazil, to intensify the search for these resources. Brazil, on the other hand, has the world's third-largest REE reserve, with potential estimates exceeding known figures; however, in 2023, it contributed only 0.02% of global production, leaving it vulnerable to growing demand. The current research focused on the concentration of REE-bearing minerals present in the processing tailings of niobium ore from the CMOC company, originating from the Catalão I Alkaline-Carbonatite Complex. Physical-chemical characterizations of the sample and froth flotation tests were conducted using three collectors: an amine (Flotigam EDA) and two fatty acids (P and LB) with corn starch (Stargill) as a depressant. Tests were conducted under different reagent dosages and pH conditions to identify the most effective parameters for the concentration of rare earth oxides (REOs). The results indicated that the REEs present in the samples were mostly light, enriched with CeO2, La2O3, and Nd2O3. The characterization of the samples by X-ray fluorescence (XRF) and particle size analysis supported the selection of flotation as the most viable technique. In the flotation tests, the EDA collector yielded grades of 2.62%, with a mass recovery of 56.46% and a metallurgical recovery of 75.99%. The P collector yielded an average grade of 2.40%, with a mass recovery of 60.28% and a metallurgical recovery of 74.10%. Finally, the LB collector showed higher REO grades (2.78%), but with mass and metallurgical recoveries around 5%. The results confirmed that flotation, with adjustments in reagent dosages and pH, is a promising route for the recovery of REE-bearing minerals from tailings, providing a sustainable and economically viable solution for utilizing tailings that are currently discarded.