Kinetics Influence of Operation Conditions on Crystal Growth of Calcium Nitrate Tetrahydrate in a Circulating Fluidized Bed

Document Type: Research Article


1 School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan, P.R. CHINA

2 School of Chemical Engineering, Sichuan University, Chengdu 610021, Sichuan, P.R. CHINA


In order to improve the traditional freezing crystallization process of calcium nitrate in nitric phosphate process, crystal growth experiments by adding Ca(NO3)2·4H2O seeds in supersaturated calcium nitrate solution in a Circulating Fluidized Bed (CFB) crystallizer were carried out on crystal growth kinetics. The results showed that the growth of Ca(NO3)2·4H2O crystals is a complicated mass transfer process. The mean mass crystal growth rate (RG) of Ca(NO3)2·4H2O increased linearly with the fluid circulated velocity at fixed relative supersaturation and enlarged with relative supersaturation increasing. The crystallization kinetics follows the first order equation. The overall activation energy and the order of the overall growth kinetics of Ca(NO3)2·4H2O crystals were calculated by the isothermal method. The RG of Ca(NO3)2·4H2O crystals remains basically stationary within the entire crystallization time in the CFB crystallizer. The results have a deep significance to exploit a new CFB crystallization process for the production of Ca(NO3)2·4H2O crystals instead of the traditional one.


Main Subjects

1] Cooper J., Lombardi R., Boardman D., Carliell-Marquet C., The Future Distribution and Production of Global Phosphate Rock Reserves, Resour. Conserv. Recy., 57: 78-86 (2011).

[2] Abdel-aal E. A. and Amer A. M., Evaluation of Sebaiya-west Phosphate Concentrate for Nitrophosphate Fertilizer Production, Miner. Eng., 8: 1221-1230 (1995).

[3]Dos Santos M.L., Riccardi C.S., Noronha A.L., Filho Edson de A., Olyveira Gabriel M., Guastaldi A.C., Influence of Aging Time of the Sol on the Synthesis of Hydroxyapatite Powders Using Ca(NO3)2·4H2O and H3PO4 as Precursors, Mater. Focus, 4: 189-192 (2015).

[4] Justnes H., Nygaard E.C., Technical Calcium Nitrate as Set Accelerator for Cement at Low Temperatures, Cement Concrete Res., 25: 1766-1774 (1995).

[5] Gadzuric S., Vranes M., Dozic S., Electrical Conductivity and Phase Transitions of Calcium Nitrate+Ammonium Nitrate+Water Mixtures, J. Chem. Eng. Data, 55: 1990-1993 (2010).

[6] Cheng G.H., Separation of Calcium Nitrate Crystals in Nitrophosphate Process, Phosphate and Compound Fertilizer, 16: 2-4 (2001).

[7] Wang S.Y., Yang X., Lu H.L., Yu L., Wang S., Ding Y.L., CFD Studies on Mass Transfer of Gas-to-particle Cluster in a Circulating Fluidized Bed, Comput. Chem. Eng., 33: 393-401 (2009).

[8] Wan L., Alvarez-Cuenca M., Upreti S.R., Lohi A., Development of a Three-phase Fuidized Bed Reactor with Enhanced Oxygen Transfer, Chem. Eng. Process., 49: 2-8 (2010).

[10] Mazumder J., Zhu J. X., Ray A.K., Optimal Design of Liquid–Solid Circulating Fluidized Bed for Continuous Protein Recovery, Powder Technol., 199: 32-47 (2010).

[12] Frazier A.W., Mullins R.C., Smith J.P., Fertilizer Materials, Crystallography of Hydrates of Calcium Nitrate, J. Agric. Food Chem., 12: 478-479 (1964).

[13] Sahin Ö., Özdemir M., Kendirci H.,d Bulutcu A.N., Determination of Growth and Dissolution Mass Rate of Boric Acid Crystals by a Simple Computer Program, J. Cryst. Growth, 219: 75-82 (2000).

[14] Taylor H.S., Hrndbre W.N., The Solubility Curves of Salt Hydrates: Calcium Nitrate, J. Am. Chem. Soc., 37: 1688-1694 (1915).

[15] Martins P.M., Rocha F.A., The Role of Diffusional Resistance on Crystal Growth: Interpretation of Dissolution and Growth Rate Data, Chem. Eng. Sci., 61: 5686-5695 (2006).

[17] Garside J., The Concept of Effectiveness Factors in Crystal Growth, Chem. Eng. Sci., 26: 1425–1431 (1971).

[18] Kumar K.V., Regression Analysis for the Two-Step Growth Kinetics of Crystals in Pure Solutions, Ind. Eng. Chem. Res., 48: 7852-7859 (2009).

[19] Martins P. M. and Rocha F. A., Kinetic Studies on the Influence of Temperature and Growth rate History on Crystal Growth, Cryst. Res. Technol., 43: 1258-1267 (2008).

[20] Clifford Y.T., Chen P.C., Tsao T.M., Growth Kinetics of CaF2 in a pH-Stat Fluidized-Bed Crystallizer, J. Cryst. Growth, 290: 576–584 (2006).