Research On Preparation And Flowability Of Large Particle Rare Earth Oxide

This thesis describes the process to prepare large particle rare earth oxide. The large particles rare earth oxide are prepared by co-precipitation method using NH4HCO3 and H2C2O4 as precipitator respectively, for light rare earth-Cerium representative and the heavy rare earth-Yttrium representative. The powder is analyzed by XRD, specific surface area analyzer, laser particle size analyzer, polishing machine.Experiment are implemented to research their effects on the size of oxide particle and the bulk density, such as precipitation mode, stirring velocity, concentration of the reactant, reactionary temperature, precipitator drop-by-drop addition speed, aging time and temperature of calcine. The optimum parameters to prepare the rare earth oxide of large particle and high bulk density are gained. Meanwhile, the effect of calcine temperature on specific surface area of big particle rare earth oxide is researched.The flowability of large particle CeO₂ powder is studied by using power comprehensive measurement. Precipitation condition and calcinations condition had influent upon flowability index of big particle CeO₂ using NH4HCO3 and H₂C₂O₄ as precipitating agent respectively that was discussed.The thermal-decomposition behavior of the CeO₂ powders precursor of oxalate precipitation in the heating process was characterized by DSC/TG. The kinetic equation of thermal-decomposition and reaction mechanism is derived from TG curve that were obtained through compute.XRD analysis showed that CeO₂ powders prepared with NH₄HCO₃ and H₂C₂O₄ two methods were all a cubic fluorite structure. And their gain size and lattice parameter are calculated by computer.Polishing capacity test indicates that polishing capacity of CeO₂ powders prepared with H₂C₂O₄ method was larger than that of CeO₂ powders prepared with NH₄HCO₃.SEM studies indicated that the CeO₂ particles prepared with NH₄HCO₃ was dispersed cauliflowerlike, that prepared with H₂C₂O₄ was dispersed hexprismatic structure.