Brazil hosts the second-largest rare earth element (REE) resources worldwide, with important LREE (monazite) deposits, associated with heavy minerals as placer deposits or with alkaline-carbonatitic deposits. The latter represent a considerable technological challenge in exploiting REEs due to their frequently fine (<10 μm) grain size. Therefore, it is imperative to improve and create new techniques and procedures to assure the economic feasibility of these resources. Chemical analysis, X-ray diffraction, scanning electron microscopy and mineral liberation analysis were performed on two different samples with low and high LREE contents from Catalão (Goiás, Brazil). All the results presented herein are thus a necessary first step to develop concentration test protocols to improve monazite recovery during mineral processing. According to these mineralogical results, the monazite’s concentration might make recovery feasible despite its fine-grained size. MLA showed that barite is mainly concentrated in the coarser size fractions for both samples, whereas monazite is liberated below 75 μm for low-grade ore and below 150 μm for high-grade ore, suggesting that a sieving procedure could reduce it to nearly 30%–50% of the total mass of the samples, with barite and quartz reduction from 53% to 57% and 54%–65%, respectively.

This study investigates an iron removal process combining size classification and magnetic separation applied to nepheline syenite from the Rio Pardo Stock (Southern Alkaline Province, Bahia, Brazil) to evaluate its suitability for ceramic and glass applications. The rock consists predominantly of feldspars (microcline and albite), with subordinate nepheline, cancrinite and biotite. Following crushing, grinding and particle-size classification, the −0.85 to +0.053 mm fractions were treated by dry Rare Earth Roll Magnetic Separation (13,000 G), whereas the <0.053 mm fraction was processed separately by Wet High-Intensity Magnetic Separation (WHIMS) under the same magnetic field. The influence of particle size on iron removal was evaluated. The highest non-magnetic recoveries (81.5–84.4 wt.%) were achieved in the intermediate particle-size fractions (0.50–0.15 mm), whereas the lowest Fe ₂ O ₃ content (0.36 wt.%) was obtained in the −0.075 + 0.053 mm fraction. Although the <0.053 mm fraction yielded the highest non-magnetic mass yield (93.0 wt.%), its Fe ₂ O ₃ content increased to 0.50 wt.%. Considering only the material subjected to magnetic separation (4771.4 g), the non-magnetic product represented 80.18 wt.% of the magnetic separation feed. The results demonstrate the beneficiation potential of the Rio Pardo nepheline syenite deposit, producing concentrates with Fe ₂ O ₃ contents as low as 0.36 wt.% and high alkali recoveries suitable for ceramic and glass applications.