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Physics and Chemistry of Minerals

, Volume 22, Issue 4, pp 207–217 | Cite as

Kinetic study of the kaolinite-mullite reaction sequence. Part I: Kaolinite dehydroxylation

  • M. Bellotto
  • A. Gualtieri
  • G. Artioli
  • S. M. Clark
Article

Abstract

The decomposition reaction of kaolinite has been investigated as a function of the defectivity of the starting material and the temperature of reaction. Time resolved energy-dispersive powder diffraction patterns have been measured using synchrotron radiation, both under a constant heating rate (heating rates from 10 to 100° C/min) and in isothermal conditions (in the temperature range 500 to 700° C). The apparent activation energy of the dehydroxylation process is different for kaolinites exhibiting a different degree of stacking fault density. The results of the analysis of the kinetic data indicate that the starting reaction mechanism is controlled by diffusion in the kaolinite particle. The diffusion process is dependent on the defective nature of both kaolinite and metakaolinite. At high temperatures, and at higher heating rates, the reaction mechanism changes and the resistance in the boundary layer outside the crystallites becomes the rate-limiting factor, and nucleation begins within the reacting particle. During the final stage of the dehydroxylation process the reaction is limited by heat or mass transfer, and this might be interpreted by the limited diffusion between the unreacted kaolinite domains and the metakaolinite matrix.

Keywords

Boundary Layer Activation Energy Heating Rate Reaction Mechanism Kaolinite 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Artioli G, Bellotto M, Gualtieri A, Pavese A (1994) Nature of structural disorder in natural kaolinites: a new model based on computer simulations of powder diffraction data and electrostatic energy calculations. Clays Clay Minerals (submitted for publication)Google Scholar
  2. Bamford CH, Tipper CFH (1980) Comprehensive chemical kinetics. Elsevier, New York, 22:41–113Google Scholar
  3. Brindley GW, Nakahira M (1957a) Role of water vapor in the dehydroxylation of clay minerals. Clay Minerals Bull 3:114–119Google Scholar
  4. Brindley GW, Nakahira M (1957b) Kinetics of dehydroxylation of kaolinite and halloysite. J Am Ceram Soc 40:346–350Google Scholar
  5. Brindley GW, Sharp JH, Patterson JH, Narahari BN (1967) Kinetics and mechanism of dehydroxylation processes. I. Temperature and vapor pressure dependence of dehydroxylation of kaolinite. Am Mineral 52:201–211Google Scholar
  6. Clark SM (1989) Energy-dispersive powder diffraction at the SRS. Nucl Inst Meth Phys Res A276:381–387Google Scholar
  7. Criado JM, Ortega A, Real C, Torres de Torres E (1984) Reexamination of the kinetics of the thermal dehydroxylation of kaolinite. Clay Minerals 19:653–661Google Scholar
  8. Donnay G, Wyart J, Sabatier G (1959) Structural mechanisms of thermal and compositional transformations in silicates. Z Kristallogr 112:161–168Google Scholar
  9. Fripiat JJ, Toussaint F (1963) Dehydroxylation of kaolinite. II. Conductometric measurements and infrared spectroscopy. J Phys Chem 67:30–36Google Scholar
  10. Goldsmith JR (1987) Al/Si interdiffusion in albite: effect of pressure and the role of hydrogen. Contrib Mineral Petrol 95:311–321Google Scholar
  11. Goldsmith JR (1988) Enhanced Al/Si diffusion in KAlSi3O8 at high pressures: the effect of hydrogen. J Geology 96:109–124Google Scholar
  12. Goldsmith JR, Jenkins DM (1985) The high-low albite relations revealed by reversal of degree of order at high pressures. Am Mineral 70:911–923Google Scholar
  13. Grimshaw RW, Heaton E, Roberts AL (1945) Refractory clays. Trans Brit Ceram Soc 44:69–92Google Scholar
  14. Hancock JD, Sharp JH (1972) Method of comparing solid-state kinetic data and its application to the decomposition of kaolinite, brucite, and BaCO3. J Am Ceram Soc 55:74–77Google Scholar
  15. Holt JB, Cutler IB, Wadsworth ME (1962) Rate of thermal dehydration of kaolinite in vacuum. J Am Ceram Soc 45:133–136Google Scholar
  16. Johnson HB, Kessler F (1969) Kaolinite dehydroxylation kinetics. J Am Ceram Soc 52:199–204Google Scholar
  17. Leonard AJ (1977) Structural analysis of the transition phases in the kaolinite-mullite thermal sequence. J Am Ceram Soc 60:37–43Google Scholar
  18. Levenspiel O (1973) Chemical reaction engineering. John Wiley, New YorkGoogle Scholar
  19. MacKenzie KJD, Brown IWM, Meinhold RH, Bowden ME (1985) Outstanding problems in the kaolinite-mullite reaction sequence investigated by 29Si and 27Al solid-state nuclear magnetic resonance: I, metakaolinite. J Am Ceram Soc 68:293–297Google Scholar
  20. McIlvried HG, Massoth FE (1973) Effect of particle size distribution on gas-solid reaction kinetics for spherical particles. Ind Eng Chem Fundam 12:225–229Google Scholar
  21. Murray P, White J (1949) Kinetics of thermal dehydration of clays. Trans Brit Ceram Soc 48:187–206Google Scholar
  22. Murray P, White J (1955a) Kinetics of thermal dehydration characteristics of the clay minerals: I. Trans Brit Ceram Soc 54:137–150Google Scholar
  23. Murray P, White J (1955b) Kinetics of thermal dehydration characteristics of the clay minerals: II. Trans Brit Ceram Soc 54:151–187Google Scholar
  24. Murray P, White J (1955c) Kinetics of thermal dehydration characteristics of the clay minerals: III. Trans Brit Ceram Soc 54:204–238Google Scholar
  25. Ortega A, Rouquerol F, Akhouayri S, Laureiro Y, Rouquerol J (1993) Kinetical study of the thermolysis of kaolinite between 30 and 1000° C by controlled rate evolved gas analysis. Appl Clay Sci 8:207–214Google Scholar
  26. Redfern SAT (1987) The kinetics of dehydroxylation of kaolinite. Clay Minerals 22:447–456Google Scholar
  27. Salje EKH (1990) Phase transitions in ferroelastic and co-elastic crystals. Cambridge University Press, Cambridge, p 202–211Google Scholar
  28. Suitch PR (1986) Mechanism for the dehydroxylation of kaolinite, dikite, and nacrite from room temperature to 455° C. J Am Ceram Soc 69:61–65Google Scholar
  29. Toussaint F, Fripiat JJ, Gastuche MC (1963) Dehydroxylation of kaolinite. I. Kinetics. J Phys Chem 67:26–30Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • M. Bellotto
    • 1
  • A. Gualtieri
    • 2
  • G. Artioli
    • 3
  • S. M. Clark
    • 4
  1. 1.CISE Tecnologie InnovativeSegrateItaly
  2. 2.Istituto di Mineralogia e Petrologia, Università di ModenaModenaItaly
  3. 3.Dipartimento di Scienze della TerraUniversità di MilanoMilanoItaly
  4. 4.SERC Daresbury LaboratoryDaresburyUK

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