| Cerium oxide due to its special electronic structure, in polishing materials, electronic ceramics, catalysts for purification of automobile exhaust gas, paint, gas sensors and other industries are widely used. In this paper, ion adsorption type rare earth concentrate by hydrochloric acid dissolution and extraction separation of rare earth cerium chloride solution as raw material, NH4HCO3 and CO(NH2)2 respectively as a precipitating agent, by direct precipitation method and homogeneous precipitation method for the preparation of a cerium oxide precursor, and then in the furnace for roasting ultrafine CeO2 powder. Study on the reactant concentrations, precipitant concentration, temperature of reaction system, aging time, calcination temperature, calcination time, ultrasonic and microwave intervention on CeO2 powder particle size and particle size distribution and so on. Through the experimental research, to find a better preparation conditions. The use of SEM, XRD, TG-DTG analysis by means of microwave, ultrasonic and microwave assisted preparation conditions for the detection of CeO2 powder, CeO2 powder particle size, particle size distribution, purity and composition of matter; and examines in a single microwave radiation heating, constant temperature water bath heating and microwave and ultrasonic with the three models, in the other experimental conditions are the same, on the preparation of CeO2 powder morphology, particle size, particle size distribution, dispersion effect.The results show that, with NH4HCO3 as precipitating agent, in a single microwave mode, cerium oxide precursor synthesis of better conditions for precipitation methods were:addition, CeCl3 concentration was 0.3 mol·L-1, NH4HCO3 and CeCl3 mass ratio were 2:1, microwave temperature of 60℃ and aging time was 60 min; precursor by TG-DTG thermal analysis, the precursor in the furnace roasting process,101 degrees from the crystallization of water, when the temperature rose to 514℃, the TG curve was a horizontal line, no change in weight, illustrate the precursor decomposition process was over. By 600℃ after roasting of the cerium oxide powder particle size are needle-shaped, mostly in the 0.3 to 0.4 μm range.The constant temperature water bath heating, single microwave radiation heating, microwave and ultrasonic wave on the three methods of preparation of ultrafine powder by CeO2 SEM analysis result shows:compared with the constant temperature water bath heating mode, single mode microwave and synergistic effect of preparation of CeO2 powder morphology rules, particle size, more uniform dispersion better, and in the microwave and ultrasonic wave under synergistic effects can be prepared from average particle size of from about 0.22 μm ultrafine CeO2 powder.In purity, and the constant temperature water bath heating compared to single microwave, ultrasonic and microwave synergistic effect especially prepared CeO2 powder with high purity, suggests a direct ion adsorbent rare earth ore extraction liquid as raw material, using microwave and ultrasonic synthesis of sub-micron high purity cerium oxide precursor.In CO(NH2)2 as a precipitating agent, in the microwave and ultrasonic wave coordination function, for the preparation of ultrafine dispersion quasi-spherical CeO2, better technology: reaction temperature 85 ℃ and reaction time was 2 hours, ultrasonic power was 1200 W and aging time was 3 hours, there is for small particles condense into a single, spherical cerium oxide polishing powder. |
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