Publication: Rare earth oxalates production from pregnant leached solution by oxalic acid precipitation
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Date
2025-08
Authors
Muhammad Nasrul Amin bin Mohd Zamzuri
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Abstract
This study investigate on how rare earth elements (REEs) can be recovered from pregnant leached solution (PLS) from ion-adsorption clays (IACs) in Kelantan, Malaysia, when oxalic acid is added. A full factorial design of experiments is used to get the most significant factors of precipitation process, such as oxalate concentration, solution pH, and reaction temperature-so that maximum yield and higher purity are reached. Elemental characterization, elemental composition, phase identification and morphology analysis had been used to characterize the PLS and product after precipitation process (aliquot solution and rare earth oxalates precipitation). Data show that the overall precipitation efficiency (PE) is between 92.84 percent and 99.74 percent. Among the tested variables, oxalate concentration (80 g/l, 120 g/l and 160 g/l) has the biggest impact, while pH value (2.0, 2.25 and 2.5) and temperature (25.0 ºC, 31.25 ºC and 37.5 ºC) work together in a close second. Statistical models of PE, proving that oxalate concentration has the lowest P-Value (0.061) closed to significantly impact the precipitation efficiency compared to other factors and interactions the three factors with regression output, R², of 78.86%. The study successfully determined the REEs content in PLS and morphology feature of REEs Oxalates, besides get a reasonable result of statistical model based on three parameters being studied.