Thermal analysis of ground dolomites

R. Ozao, M. Ochiai, Atsushi Yamazaki, R. Otsuka

    Research output: Contribution to journalArticle

    24 Citations (Scopus)

    Abstract

    The characteristics of ground dolomites which have undergone a change in crystal structure and of those almost free from structural change, were studied mainly by thermal analysis. Firstly, pulverized samples passed through a 325-mesh Tyler sieve were ground further for 1, 2, 3, 5 and 24 h in order to observe their change with progressive grinding. The X-ray diffraction (XRD) and IR patterns and TG-DTA curves obtained in flowing 100% CO2 gas indicated a gradual loss of the cation ordering characteristic of dolomite structure up to a grinding period of 24 h when a new phase of lower ordering appeared; this confirmed the results of earlier investigators. To characterize further the gradually developing new phase which was not apparently distinguished by XRD or IR analysis, TG-DTA curves were obtained under varying CO2 partial pressures. It was found that the new phase decomposed in a straightforward manner, similarly to that of magnesite and quite differently from that dolomite, its decomposition temperature and rate were dependent upon the CO2 partial pressure. In addition, the influence of grain size and particle size distribution on the temperature and shape of the endothermic peak of the DTA curve was studied. It was found that the peak shape is affected by the grain size, and moreover that the temperature range of the endothermic peak is affected by the size and, more importantly, the size distribution of the particles.

    Original languageEnglish
    Pages (from-to)183-198
    Number of pages16
    JournalThermochimica Acta
    Volume183
    Issue numberC
    DOIs
    Publication statusPublished - 1991 Jul 5

    Fingerprint

    Differential thermal analysis
    Thermoanalysis
    thermal analysis
    Partial pressure
    grinding
    partial pressure
    Magnesite
    X ray diffraction
    curves
    Sieves
    grain size
    sieves
    Particle size analysis
    Temperature
    Cations
    Crystal structure
    Gases
    Positive ions
    particle size distribution
    diffraction

    ASJC Scopus subject areas

    • Chemistry (miscellaneous)
    • Physical and Theoretical Chemistry

    Cite this

    Thermal analysis of ground dolomites. / Ozao, R.; Ochiai, M.; Yamazaki, Atsushi; Otsuka, R.

    In: Thermochimica Acta, Vol. 183, No. C, 05.07.1991, p. 183-198.

    Research output: Contribution to journalArticle

    Ozao, R. ; Ochiai, M. ; Yamazaki, Atsushi ; Otsuka, R. / Thermal analysis of ground dolomites. In: Thermochimica Acta. 1991 ; Vol. 183, No. C. pp. 183-198.
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