Multiscale Flotation Testing for the Recovery of REEs-Bearing Fluorapatite from a Finnish Carbonatite Complex Deposit Using Conventional Collectors and Lignin Nanoparticles

Apatite and rare earth elements (REEs) are vital to the European Union's economic growth and resource security, given their essential roles in fertilizers, green technologies, and high-tech applications. To meet rising demand and reduce reliance on imports, the ex-ploitation of domestic deposits has become increasingly important. This study investi-gates the beneficiation potential of ore from a carbonatite complex (Finland), focusing on the recovery of fluorapatite concentrate through froth flotation. The research addresses two key objectives: evaluating the potential for REE enrichment alongside fluorapatite concen-tration using conventional anionic and amine-based reagents, and assessing separation efficiency when partially substituting the most effective conventional collectors with bio-based organosolv lignin nanoparticles. Adequate recovery rates for apatite and REEs were achieved using common anionic col-lectors, such as hydroxamate and sarcosine, yielding P grades of 23.4% and 21.5%, and recoveries of 96.4% and 89.2%, respectively. Importantly, concentrate quality remained stable with up to 30% reduction of conventional collectors and addition of organosolv lig-nin. Bench-scale trials further validated the approach, demonstrating that lanthanum and cerium recoveries exceeded 71%, alongside satisfactory apatite recovery. The findings highlight lignin nanoparticles as an environmentally friendly alternative to conventional reagents in apatite flotation, offering potential to reduce the environmental footprint of the process without compromising flotation kinetics or concentrate quality.