Continuous Precipitation Process of Ce2（C2O4）3 Under Addition of Seed Crystals

Abstract

In the cup type precipitator, Ce2(C2O4)3 was used to simulate Pu(C2O4)2 for continuous precipitation experiments. Keeping other conditions unchanged, process conditions including temperature at 30.0-50.0 ℃, Ce(NO3)3 concentrations of 0.084 mol/L and 0.167 mol/L, crystal seed addition ratios in the range of 0-2.0×10-1 and seed feeding position were investigated respectively, to find out their effects on the particle size distribution and morphology of Ce2(C2O4)3 particles. When the concentration of Ce(NO3)3 is 0.167 mol/L at 50.0 ℃, the D50 maximum values(D50 is the value of the particle diameter at 50% in the cumulative distribution) of Ce2(C2O4)3 particles can increase by 62.2 μm compared with that without crystal seeds. When the concentration of Ce(NO3)3 is 0.167 mol/L and the crystal seeds are added in the peripheral vortex region and the central vortex region at 50.0 ℃, the corresponding D50 maximum values are 154.1 μm and 120.7 μm respectively. When the temperature changes from 30.0 ℃ to 50.0 ℃, the maximum value of precipitated particles D50 increases with temperature. Under various process conditions, and when D50 reaches the maximum, the shape of Ce2(C2O4)3 particles is dominated by regular flaky long strips, the proportion of fragmented and irregular flaky aggregates is small. The grain growth mode of Ce2(C2O4)3 belongs to the spiral growth mechanism, and the thickness of the single layer of grain is about 16 nm.

Keywords

• cup type precipitator
• continuous precipitation
• ce2(c2o4)3
• particle size distribution