Optimizing monazite enrichment from zircon for efficient rare earth element recovery using tetraethylammonium bis(2-ethylhexyl)-phosphate ([N2222][DEHP]) ionic liquid collector

Rare earth elements (REEs) are critical to a wide range of high-tech applications, including electronics, renewable energy technologies, and advanced defense systems. However, the sustainable and efficient extraction of REEs from low-grade ores remains a significant challenge. This study investigates the enrichment of monazite as a REEs-bearing mineral from zircon using mini-column flotation. A pre-treatment process of the zircon sample, containing 57.90% ZrO2 and 1.22% Rare earth oxides (REOs), was conducted using Carpco magnetic separator in order to recover monazite. Two pre-concentrates (A and B) were obtained, with REOs content of 12.50% and 16.54%, and high recoveries of 96.82% and 89.20%, respectively. The flotation process for both pre-concentrates was investigated using tetraethylammonium bis(2-ethylhexyl)-phosphate ([N2222][DEHP]) ionic liquid as a collector for monazite flotation. This approach demonstrated high performance, yielding monazite-rich concentrates with up to 40% REOs content. Box-Behnken design optimized flotation conditions with ([N2222][DEHP]) produced monazite concentrates (A and B) containing 39.88% and 43.37% REOs, with recoveries exceeding 80%. The separation efficiency was evaluated using many analytical techniques which evidenced the potential of ([N2222][DEHP]) as an alternative to conventional collectors and presents a promising pathway for enhancing the sustainable enrichment of REEs.