The Study On Agglomeration Of Cerium Oxalate Prepared By Precipitation

In this paper, the precursor of CeO2 powders—Ce2(C2O4)3 was prepared by continuous precipitation method with cerium nitrate and oxalate as raw materials and precipitator respectively. The study includes mainly three parts: the first part is that the effect of operational conditions on correlation parameter of crystallization kinetics; the second part is that the effect of the different conditions of nucleation and growth process on the grain size, degree of agglomeration and particle size; the third mainly study on the preparation of large particle and mathematical model.In the study on correlation parameter of crystallization process, the influence of operational parameters such as feed position, micro-mixing efficiency, feeding speed and reactant concentration on nucleation velocity and growth rate was studied. Nucleation velocity and growth rate were respectively obtained by fitting experimental data according to empirical formula as follows: B = 3. 01×10⁸ΔC^1.65, R 2 =0.91; G = 5 .17×10^-6ΔC^1.82, R 2 =0.97。The process of precipitation was divided two processes: nucleation (nucleation take place mainly in this step, also partial growth) and growth process (there is mainly growth and agglomeration without nucleation). The effect of conditions of the precipitation on particles size of crystallizer and content of agglomeration was investigated in the nucleation process and optimum operational conditions of nucleation were obtained. The influence of different growth environment namely agitation speed, growth temperature, PH, electrolyte and dispersant (PEG1000) concentration on final agglomerates size was studied. The preparation of large particle Ce2(C2O4)3 was studied according to result of crystallization kinetics. In the study of agglomeration the relationship of particle size with specific power input and super saturation was obtained as follows: This relationship was generalized as follows:...