Effectiveness of sieving and grinding in measuring the concentration of rare earth elements from ion adsorption clay in Lumut, Perak

This study examines the effect of pre-treatment techniques of sieving and grinding on the concentration and extractable yield of rare earth elements (REEs) from ion adsorption clay (IAC) in Lumut, Perak. Three 3 kg samples were prepared: raw (untreated), sieved to <600 μm, and ground to <600 μm. The REE concentrations in the digested samples were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), while the mineralogical composition was determined using X-ray Diffraction (XRD). The results showed that sieving significantly enriched light REEs (LREEs), with La and Nd up 38.7% and 40.1%, respectively, compared to the raw sample. However, only 1.65 kg of sample was retained post-sieving, resulting in a lower total recovery of La (76.3%). In contrast, grinding retained 2.92 kg and yielded a higher La recovery (84.5%) despite a lower concentration. These findings demonstrate a trade-off between concentration and mass yield: sieving is effective for enriching REEs in fine fractions, whereas grinding maximizes total extractable REEs. This study emphasizes the importance of integrating both concentration and mass balance in evaluating REE processing methods. It supports sieving as a selective enrichment technique and grinding as a superior alternative for maximizing total recovery from IAC.