PHYSICO-CHEMICAL BASIS OF THE PROCESS ROF SEPARATION OF RARE EAFTH ELEMENTS

The paper presents the results of laboratory study into the processes for separation and enrichment of rare earth element (REE) concentrates in a natural ratio of lanthanum and cerium line light group. The separation process is based on difference in solubility of 3- and 4-valence cerium components in nitric acid. Oxidative drying of REE concentrates allows for a sufficiently complete cerium conversion to a 4-valence state. lanthanum, neodymium and praseodymium oxides are readily soluble in weak nitric acid with a 4 to 5 PH value, while cerium remains as СeO2 oxide in a solid phase. lanthanum content of liquid phase in the first REE concentrate has grown from 25% to 50%, while that of cerium has gone down from 55% to 25%. Cerium concentration in the second REE concentrate has grown from 55% to 85%. The production of lanthanum and cerium enriched concentrate has added to their more efficient application as catalysts in metallurgy.