摘要
In order to improve the recovery rate of rare earth,the effect of P_(2)O_(5) and cooling rate on the selective precipitation of CaO-SiO_(2)-TiO_(2)-P_(2)O_(5)-Nb_(2)O_(5)-CeO_(2)-CaF_(2) slag system was explored using X-ray powder diffraction,a scanning electron microscope,an electron probe micro-analyzer and a confocal laser scanning microscope.The apatite(Ca_(2.02)Ce_(7.98)Si_(6.00)O_(26.00))is tiny and difficult to be separated from the slag without P_(2)O_(5).When the addition of P_(2)O_(5) is 6 wt%-10 wt%,the cerium and phosphorus are found to be enriched in britholite(Ca_(5-x)Ce_(x)[(SiO_(4))_(x)(PO_(4))_(3-x)]F)phase while x is negatively correlated with P_(2)O_(5) content in the slag.The influence of P_(2)O_(5) and cooling rate on the non-isothermal crystallization kinetics was also investigated.For the cooling rate between 5 and 40℃/min,continuous cooling transformation diagram of britholite was constructed when the P205 content is between 6 wt%-10 wt%.The modified Avrami model was applied to determine the crystallization mode of slag with 10 wt%P_(2)O_(5).It is shown that the crystallization mode is diffusion-controlled with constant nucleation rate and one-dimensional growth.In consideration of quantity and volume of crystals,the reasonable cooling rate is between 10and 30℃/min.
基金
Project supported by the Major Projects of Inner Mongolia Natural Science Foundation (2018ZD07)
Inner Mongolia Natural Science Foundation (2020BS05016)
Open Project for Key Basic Research of the Inner Mongolia Autonomous Region (20140201)
Open Project for Major Basic Research of Inner Mongolia (0406091701)
Scientific Research Project of Inner Mongolia (ZDZX2018032)。
