Leaching Process of Weathered Crust Elution-Deposited Rare Earth Ore by Alkaline Earth Metal Carboxylate

This study explores the use of alkaline earth metal carboxylates as sustainable alternatives to conventional ammonium-based lixiviants for the eco-friendly extraction of weathered crust elution-deposited rare earth ores. We investigated the impact of lixiviant concentration, pH, and leaching temperature on the extraction efficiency of rare earths and aluminum, utilizing magnesium acetate and calcium acetate alongside traditional ammonium salts. The results showed that a leaching rate exceeding 91% for rare earths was achieved, while aluminum leaching remained under 30% at 298 K, pH 6.5–7.0, and 0.20 mol/L concentration of carboxylates. Notably, magnesium acetate was particularly effective in extracting medium and heavy rare earths at lower concentrations. A double electric layer model was used to clarify the leaching mechanism, indicating that zeta potential and double electric layer thickness were significantly affected by the concentration and pH of the leaching agents. Overall, this method presents an efficient approach for low-impurity extraction, offering valuable insights for sustainable mineral resource development.