Vapor phase extraction and separation of rare earths from bastnaesite concentrate mediated by vapor complexes

Vapor phase extraction and mutual separation characteristics of rare earths mediated by vapor complex in the LnCl3-KCl systems (Ln = rare earth) were investigated using chemical vapor transport along a temperature gradient. Bastnaesite concentrate (LnFCO3) and potassium carbonate were used as raw material and precursor of the complex former, KCl, respectively. The bastnaesite decomposes thoroughly to oxyfluoride (LnOF) on heating above 460 °C. Chlorination of the resulting oxyfluoride is complete within 2 h at 1000 °C in the presence of N2-Cl2 gas where N2/Cl2 = 6/1. Neodymium chloride is generally concentrated to 38% at the lower temperature fractions (650-770 °C), and lanthanum chloride to 37% at the higher temperature fractions (above 960 °C). The yield of rare earth after reaction for 82 h increases with increasing amount of complex former: 1/0.67<1/2 (= Ln/K). The yield was also optimized by the addition of an adequate amount of active carbon powder as deoxidant.