论文部分内容阅读
通过pH值在线检测和Co浓度离线分析方法,结合热力学数据建立的平衡模型,对草酸钴沉淀过程的溶液体系进行动态模拟。结果表明,随着沉淀反应的进行,体系pH值和过饱和度不断下降,沉淀率则逐渐升高,沉淀过程依次经历诱导期、成核期和生长期。在较高的反应物浓度下,沉淀反应速度更快,体系pH值和过饱和度下降速度随之增大,而沉淀率也有所增加。SEM和激光粒度分析结果表明,较高的反应物浓度下所得草酸钴粉体的一次晶粒粒径较小,易于团聚形成尺寸较大的刺球状团聚体。通过引入Davies活度系数,pH值在线分析模型和Co浓度离线分析模型吻合度高,模拟结果重现性好。
The solution system of precipitation process of cobalt oxalate was simulated dynamically by on-line pH value detection and off-line analysis of Co concentration combined with the equilibrium model established by thermodynamic data. The results showed that with the progress of precipitation reaction, the pH value and supersaturation of the system decreased continuously, and the precipitation rate increased gradually. The precipitation process followed the induction, nucleation and growth stages. At higher reactant concentrations, the precipitation reaction rate is faster, the system pH and supersaturation declining rate increases, and the precipitation rate also increases. The results of SEM and laser particle size analysis showed that the primary crystal grain size of cobalt oxalate powder obtained at the higher reactant concentration was smaller and easily aggregated to form the spherulitic aggregates with larger size. By introducing the Davies activity coefficient, the on-line analytical model of pH value is in good agreement with the off-line analytical model of Co concentration, and the simulation result has good reproducibility.