The effects of different annealing conditions on the phase formation with NaZn13 structure were investigated in La(Fe1–xCox)11.9Si1.1 (x=0.068) compounds. It was found that the 1:13 phase was not formed directly from the melt upon cooling but via a peritectic reaction between the pro-peritectic γ-Fe and the La-rich phase. Annealing temperature was very important for the formation of 1:13 phase. Ice water was confirmed to be a preferable quenching medium. La(Fe1–xCox)11.9Si1.1 (x=0.068) compounds with almost single 1:13 phase were obtained at 1473 K after 15 d.
During the last decade, China rare earth (RE) industry has made significant progress and become one of the most important producers in the world. In this paper, the recent developments in both fundamen-tal research and industrial application are briefly reviewed: (1) the development and application of Theory of Countercurrent Extraction, (2) the novel solvent extraction process and its application in industry for separat-ing heavy rare earth elements (Tm, Yb, Lu), yttrium (Y), and scandium (Sc), (3) the on-line analysis and automatic control of countercurrent extraction, (4) the eco-friendly process for RE/Th separation of bastna-site in Sichuan Province and electrochemical process for Eu/RE separation, and (5) the optimized flow-charts for typical rare earth minerals in China.
