【摘 要】
：
The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The result
【机 构】
：
School of Materials and Metallurgy
论文部分内容阅读
The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2 were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps.The first step occurs in the temperature range of 425-540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF reacts with CaO to produce RE2O3 and CaF2, and Ce2O3 is oxidized to CeO2. During this step, CaCO3 is formed at about 500 ℃. The second step takes place in the temperature range of 610-700 ℃, and the reactions are monazite decomposition into RE2O3,Ca5F(PO4)3 and Ca3(PO4)2 by CaO and CaF2. In this process, the decomposition ability is improved because CaO from CaCO3decomposing has high chemical activity. In calcining process, the new formed Ca5F(PO4)3 restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.
其他文献
Fe-Al intermetallic/TiC-Al2O3 ceramic composites were successfully prepared by self-propagating high-temperature synthesis (SHS) from natural ilmenite, aluminiu
Chloride ion critical content was studied under soaking and cycle of dry and wet conditions,with three electrochemical nondestructive measuring techniques, i e,
Synthetic Aperture Radar (SAR) has become one of the important tools for shallow water bathymetry surveys. This has significant economic efficiency compared wit
ZnO nanopowders were prepared by oxidizing Zn vapor in the atmosphere of mixture gas of Ar and O2 at low pressure. Tetrapod nanowhiskers synthesized at a pressu
A preferable honeycomb ceramics of Al2TiO5-TiO2-SiO2 doped by CeO2 and Er2O3 with high performance was prepared by means of extrusion molding and the effects of
The cotyledons of cucumber were used to investigate the effects of Nd3+ and La3+ on physiological characters in respect of plant resistance. The cucumber cotyle
The detailed kinetic model of selective non-catalytic reduction (SNCR) of nitric oxide, including sodium species reactions, was developed on the basis of recent
The organic gel-thermal reduction process was successfully used for the preparation of magnetic metal Ni, Fe, Fe-Ni fine fibers from raw materials of citric aci
To get high purity caprolactam is a challenging task in the chemical fiber industry. To date, reports on the prediction of the distribution of caprolactam and i