Influence of the Alkali-promoted phase transformation in monazite for selective recovery of rare-oxides using deep eutectic solvents

The physico-chemical changes occurring during the high-temperature phase transformation of monazite in presence Na2CO3 at 1000 °C for 2 h duration monazite: ratios between 1.0 and 5.0, were investigated. formation sodium lanthanide phosphates was prevalent above a monazite:alkali ratio 2, however, below this ratio, dephosphorization as Na3PO4 Ce1-xLnxO2-x/2 solid solutions occur offering unique selectivity rare-earth oxide separation from mineral matrix. Cyclic voltammetry pure CeO2, La2O3, Nd2O3, PrO2/Pr2O3 carried out deep eutectic solvent Ethaline (1:2 mixture choline chloride ethylene glycol) proving electrochemical activity these oxides. Electrodissolution oxides water-leached after reaction with 1:1 0.1 mol/L glucose solution showing preferential solubility 23.85% Nd2O3. In contrast, La2O3 found to be insoluble. We also observed that electrodissolution water leached not possible because inert behaviour solutions. Avoiding cerium oxidation process will lead method further processing using staged electro-chemical winning