Non-Isothermal Calcination Kinetics of Phosphate Rock

Abstract

The kinetics of thermal decomposition of the phosphate rock was studied by means of thermal analysis techniques (TG/DTG) in inert nitrogen (N2) atmosphere at heating rates of 2, 5, 10, and 20 K min-1. TG and DTG measurements indicated that calcination of the phosphate rock has single-stage degradation in between 873-1173 K. Kissinger–Akahira–Sunose (KAS) and Flynn-Wall-Ozawa (FWO) isoconversional methods were applied to the data obtained from TG and DTG curves and the activation energies were found as 170 ve 187 kJmol-1, respectively. It was determined that the thermal decomposition mechanism of phosphate rock was occurred via nucleation and growth (-ln(1-α)2/3) mechanism. Pre-exponentional factor (lnA) was determined as 20.47.

Keywords

• Phosphate rock, Isoconversional methods, Activation energy, Non-isothermal kinetic analysis.

Fosfat Kayasının İzotermal Olmayan Bozunma Kinetiği

Öz

Mazıdağı fosfat kayasının inert ( N2) ortamda ısıl bozunma kinetiği 2, 5, 10 ve 20 K dak-1 ısıtma hızlarında termal analiz teknikleri (TG/DTG) ile incelendi. TG ve DTG ölçümlerinde 873-1173 K sıcaklık aralığında fosfat kayasının ısıl bozunmasının tek basamaklı bozunma olduğu görüldü. TG ve DTG eğrilerinden elde edilen verilere eş dönüşüm metotları Kissinger–Akahira–Sunose (KAS) ve Flynn-Wall-Ozawa (FWO)uygulanarak aktivasyon enerjileri sırasıyla 170 ve 187 kJmol-1 olarak bulundu. Fosfat kayasının ısıl bozunmasının çekirdeklenme ve büyüme (-ln(1-α)2/3) mekanizmasına göre meydana geldiği belirlendi. Ön üssel faktör (ln A) ise 20.47 olarak tespit edildi.

Anahtar Kelimeler

• Fosfat kayası, Eş dönüşüm metotları, Aktivasyon enerjisi, İzotermal olmayan kinetik analiz.

Kaynakça

1. Maden Tetkik ve Arama. “Mazıdağı ve Fosfat Gerçeği Raporu”. Maden Tetkik ve Arama, Ankara, Türkiye, 2006.
2. Jasinski SM. “Phosphate Rock”. Minerals Yearbook, 56, 200 Aydin I, Imamoglu Ş, Aydin F, Saydut A, Hamamci C. “Determination of Mineral Phosphate Species in Sedimentary Phosphate Rock in Mardin, SE Anatolia, Turkey by Sequential Extraction”. Microchemical Journal, 91(1), 63-69, 2009.
3. Abouzeid AZM. “Physical and Thermal Treatment of Phosphate Ores-An Overview”. International Journal of Mineral Processing, 85(4), 59-84, 2008.
4. Özer AK. “The Characteristics of Phosphate Rock for Upgrading in a Fuidized Bed”. Advanced Powder Technology, 14(1), 33-42, 2003.
5. Abouzeid AZM, El-Jallad IS, Orphy MK. “Calcareous Phosphates and Their Calcined Products”. Minerals Science and Engineering, 12(2), 73-83, 1980.
6. Simon P. “Isoconversional Methods: Fundamental, Meaning and Application”. Journal of Thermal Analysis and Calorimetry, 76(1), 123-132, 2004.
7. Sbirrazzuoli N, Vincent L, Mija A, Guio N. “Integral, Differential and Advanced Isoconversional Methods: Complex Conversion–Time Curves”, Chemometrics and Intelligent and Laboratory Systems, 96(2), 219-226, 2009. Isothermal Predicted
8. Vyazovkin S. “A Unified Approach to Kinetic Processing of Nonisothermal Data”. International Journal of Chemical Kinetics, 28(2), 95-101, 1996.

9. Vyazovkin S, Wight CA. “Isothermal and Nonisothermal Reaction Kinetics in Solids: In Search of Ways Toward Consensus”. The Journal of Physical Chemistry A, 101(44), 8279-8284, 1997.
10. Opfermann JR, Kaisersberger E, Flammersheim HJ. of Advantages and Limitations”. Thermochimica Acta, 391(1-2), 119-127, 2002. Thermoanalytical Data
11. Lodha TR, Sinha NK, Srivastava AC. “Characterization of Low Grade rock Phosphate and Their Beneficiation for the Fertilizer Industry”. Chemical age of India, 35(1), 15−22, 19 Özer AK, Gülaboğlu MŞ, Bayrakçeken S. “Physical Structure and Chemical and Mineralogical Composition of the Mazıdağı (Turkey) Phosphate Rock”. Industrial & Engineering Chemistry Research, 39(3), 679-683, 2000.
12. Maciejewski M. “Computational Aspects of Kinetic Analysis. Part B: The ICTAC Kinetics Project-The Decomposition Kinetics of Calcium Carbonate Revisited, or Some Tips on Survival in the Kinetic Minefield”. Thermochimica Acta, 355(1-2), 145-154, 2000.
13. Vyazovkin S. “Computational Aspects of Kinetic Analysis. Part C. The ICTAC Kinetics Project-The Light at the End of the Tunnel”. Thermochimica Acta, 355(1-2), 155-163, 2000.
14. Burnham AK. “Computational Aspects of Kinetic Analysis. Part D: The ICTAC Kinetics Project-Multi-Thermal-History Model-Fitting Isoconversional Methods”. Thermochimica Acta, 355(1-2), and 165-170, 2000. Their Relation to
15. Roduit B. “Computational Aspects of Kinetic Analysis. Part E: The ICTAC Kinetics Project-Numerical Techniques and Kinetics of Solid State Processes”. Thermochimica Acta, 355(1-2), 171-180, 2000.
16. Morancho JM, Salla JM, Cadenato A. Fernández-Francos, X, Ramis X, Colomer P, Calventus Y, Ruíz R. ‘‘Kinetic Studies of the Degradation of Poly(vinyl alcohol)-Based Proton- Conducting Thermochimica Acta, 521(1-2), 139-147, 2011. “Estimating Temperatures’’. Doyle CD. Isothermal Life From
17. Thermogravimetric Data”. Journal of Applied Polymer Science, 6(24), 639-642, 1962.
18. Kissinger H. “Variation of Peak Temperature With Heating Rate in Differential Thermal Analysis”. Journal of Research of the National Bureau of Standards, 57(4), 217-221, 1956.
19. Akahira T, Sunose T. “Joint Convention of Four Electrical Institutes”. Science Technology, 16, 22–31, 1971. New Ozawa T. “A Method of Analyzing
20. Thermogravimetric Data”. Bulletin of the Chemical Society of Japan, 38(11), 1881-1886, 1965.
21. Flynn J, Wall L. “A Quick, Direct Method for the Determination Thermogravimetric Data”. Journal of Polymer Science Part B: Polymer Letters, 4(5), 323-328, 1966. Activation Energy from
22. Ortega A. “Some Successes and Failures of the Methods Based on Several Experiments”. Thermochima Acta, 284(2), 379–387, 1996.
23. Halikia I, Zoumpoulakis L, Christodoulou E, Prattis D. “Kinetic Study of the Thermal Decomposition of Calcium Carbonate by Isothermal Methods of Analysis”. The European Journal of Mineral Processing and Environmental Protection, 1(2), 89-102, 2001.
24. Galwey AK. Brown ME. Kinetic Background to Thermal Analysis and Calorimetry. Editor: Brown ME. Handbook of Thermal Analysis and Calorimetry Principles and Practice, 691, Amsterdam, Holland, Elsevier Scientific, 19 Ninan KN, Krishnan K, Krishnamurthy VN. “Kinetics and Mechanism of Thermal Decomposition of in Situ generated Calcium Carbonate”. Journal of Thermal Analysis, 37(7), 1533-1543, 1991.
25. Sanders JP, Gallagher .K. “Kinetic Analyses Using Simultaneous Decomposition of Calcium Carbonate in Argon”. Thermochimica Acta, 388(1-2), 115-128, 2002. Measurements Part I:
26. Roduit B. “Computational Aspects of Kinetic Analysis. Part E: The ICTAC Kinetics Project-Numerical Techniques and Kinetics of Solid State Processes”. Thermochimica Acta, 355(1-2), 171-180, 2000.