(1. 中南大学 化学化工学院，长沙 410083；2. 深圳市格林美高新技术股份有限公司，深圳 518104；
3. 中南大学 冶金科学与工程学院，长沙 410083；
4. Department of Chemical and Process Engineering, University of Sheffield, Mappin Street S1 3JD, UK)
摘 要: 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。
关键字: 草酸钴；沉淀；粉体；过饱和度；热力学
precipitation of cobalt oxalate
（1. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
2. Shenzhen GEM High-Tech Co., Ltd., Shenzhen 518116, China;
3. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;
4. Department of Chemical and Process Engineering, University of Sheffield, Mappin Street S1 3JD, UK）
Abstract:Based on online pH value testing and offline Co concentration analysis, a thermodynamic equilibrium model was established for dynamic simulation on precipitation of cobalt oxalate. The obtained results indicate that the precipitation process undergoes induction, nucleation and growth period successively along with decreased pH value and supersaturation, and increases the precipitation ratio. At higher reactant concentration the pH value and supersaturation fall down rapidly as a result of the faster reaction rate, and the precipitation ratio is slightly larger. SEM and laser particle size analysis demonstrate that at higher reactant concentration the primary particles generated with smaller size tend to assemble into spiky agglomerates with larger particle size. By introduction of Davies activity coefficient into the thermodynamic model, the higher consistency is achieved between the online pH based simulation and the offline Co concentration based simulation, and the high repeatability in the simulation is attained.
Key words: cobalt oxalate; precipitation; powder; supersaturation; thermodynamic
