(1. 中南大學(xué) 化學(xué)化工學(xué)院，長沙 410083；2. 深圳市格林美高新技術(shù)股份有限公司，深圳 518104；
3. 中南大學(xué) 冶金科學(xué)與工程學(xué)院，長沙 410083；
4. Department of Chemical and Process Engineering, University of Sheffield, Mappin Street S1 3JD, UK)
摘 要: 通過pH值在線檢測和Co濃度離線分析方法，結(jié)合熱力學(xué)數(shù)據(jù)建立的平衡模型，對草酸鈷沉淀過程的溶液體系進行動態(tài)模擬。結(jié)果表明，隨著沉淀反應(yīng)的進行，體系pH值和過飽和度不斷下降，沉淀率則逐漸升高，沉淀過程依次經(jīng)歷誘導(dǎo)期、成核期和生長期。在較高的反應(yīng)物濃度下，沉淀反應(yīng)速度更快，體系pH值和過飽和度下降速度隨之增大，而沉淀率也有所增加。SEM和激光粒度分析結(jié)果表明，較高的反應(yīng)物濃度下所得草酸鈷粉體的一次晶粒粒徑較小，易于團聚形成尺寸較大的刺球狀團聚體。通過引入Davies活度系數(shù)，pH值在線分析模型和Co濃度離線分析模型吻合度高，模擬結(jié)果重現(xiàn)性好。
關(guān)鍵字: 草酸鈷；沉淀；粉體；過飽和度；熱力學(xué)
precipitation of cobalt oxalate
DENG Wei2, ZHOU Ji-feng2, KUAI Qin2, M. HOUNSLOW4
（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
