Bastnaesite Calcination

Abstract

residues were analyzed. A quantitative xray fluorescence spectrographic technique was developed by which lanthanum, cerium, praseodyraium, and neodymium could be determined as major components. The method involved the dissolution of rare earth material in fused borax followed by the x-ray analysis of the borax glass discs. The dilution thus obtained satisfactorily minimized errors resulting from absorption and enhancement effects and heterogeneity variations. The analyses of four samples of widely varying composition showed a mean error of less than 5%. With these four elements, interference from other rare earth oxides is generally insignificant. A semiquantitative technique for the same elements based on the interpretation of qualitative x-ray spectrograms was developed. It was concluded that solid bastnaesite rare earth material reacted with a kerosene solution of alkylphosphoric acids to yield products soluble to varying degrees in kerosene, water, alkali, and acid. Rare earth carbonates, with some exceptions, were more reactive than the oxides. Rare earth carbonates were more reactive with Dowsol-12, whereas the rare earth oxides were more reactive with Dowsol-17. There was evidence that the rare earths in the natura1 materials were in a true solid solution or in mixed crystals, rather than existing as discrete compounds. Synthetic mixtures of the pure oxides and carbonates of the same elemental composition as the natural materials did not respond the same as these natural products to the reaction and extraction treatment. The cerium in bastnaesite ore was found to be, at least in part, in the cerous rather than the ceric state as evidenced by its acid solubility. Cerium and praseodymium were found to be very similar in many of their reactions and solubilities. No other combination studied was found to be so closely related. This similarity of reactivity may be the result of the formation of a tetravalent rare earth complex in the case of both elements. Lanthanum and neodymium maintained their tervalent status. A separation scheme with industrial potentialities may be feasible based on the reaction of Dowsol-12 and the bastnaesite carbonates. The digestion scheme was outlined. (Dissertation Abstr., 22: No. 7, 1962.)