Authors: N.A. Zolotukhina, Ch.O. Belousova, Yu.A. Vinidiktova, D.A. Barantsev

Title of the article: Influence of pH on rare earth concentrate extraction from coal beneficiation waste of JC «TSOF BEREZOVSKAYA»

Year: 2025, Issue: 6, Pages: 37-49

Branch of knowledge: 2.6.8. Technology of rare, scattered and radioactive elements

Index UDK: 546.05:546.65, 661.1

DOI: 10.26730/1999-4125-2025-6-37-49

Abstract: Coal ash and untreated coal waste are currently being studied as promising sources for obtaining rare earth elements. Acid leaching often serves as the initial stage in the process of extracting REE from coal by-products. Organic acids are increasingly recognized as an environmentally friendly and effective selective leaching agent. The selectivity of rare earth elements to oxalic acid is explained by the high degree of interaction of trivalent rare earth element ions with oxalate ions, as well as the extremely low ability of rare earth metal oxalate compounds to dissolve in water. The presence of impurities in the leaching solution hinders the selective extraction of rare earth elements. The volume of oxalic acid required for lanthanum precipitation is determined by the concentration of both lanthanum itself and accompanying impurities, since oxalic acid exhibits the ability to form chelate complexes with various trivalent cations. In this regard, the total amount of oxalic acid for lanthanum precipitation was determined based on a three-fold stoichiometric excess of oxalic acid relative to REE, as well as taking into account the concentrations of other components in the multicomponent solution, such as aluminum, iron, and calcium. In this study, a parametric investigation was conducted to analyze the influence of oxalic acid dosage, precipitation pH, temperature, and iron and aluminum ion concentrations on the efficiency of rare earth-oxalate precipitation. Precipitation of rare earth element oxalates was tested on model solutions. Analysis of experimental results under various acid-base conditions demonstrates that the most effective lanthanum extraction while simultaneously reducing iron and aluminum concentrations is achieved at pH=2.0. A further increase in pH is undesirable as it leads to an increase in the amount of undesirable components in the resulting concentrate

Key words: coal waste extraction leaching oxalic acid

Receiving date: 19.06.2025

Approval date: 15.11.2025

Publication date: 22.12.2025

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