Separation of Heavy Rare Earth Elements from Calcium and Light Rare Earth Elements Using Estonian Phosphorite Ore Raw Material

Separation of heavy rare earth elements from calcium and light rare earth elements extracted from Estonian phosphorite ore by acid leaching and subsequent liquid extraction has been conducted and analyzed. For initial leaching, nitric acid, hydrochloric acid, and orthophosphoric acid with different concentrations have been utilized. For the final separation of heavy rare earth elements, a liquid extraction with bis(2-ethylhexyl) phosphate (D2EHPA) or 2-ethylhexyl hydrogen-2-ethylhexyl phosphonate (P507) at different acidic concentrations has been applied. After leaching and extraction, all samples were characterized using the inductively coupled plasma mass spectrometry method (ICP-MS/MS). Optimal conditions for both extracting agents have been established. All rare earth elements + Y have been recovered in acid leaching, and heavy rare earth elements (elements Gd-Lu) have been selectively recovered by D2EHPA with 5 M nitric acid leaching and by P507 with 1 M nitric acid leaching. The presence of Sc has not been detected in Estonian phosphorite ore.