STP472

    Characterization of the Properties of Commercial Lime by Surface Area Measurements and Scanning Electron Microscopy

    Published: Jan 1970


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    Abstract

    Reactivity of lime (CaO, CaO-MgO) is a function of surface area and pore space which is related to temperature or time of calcination or both. The development and distribution of pore space in calcined stone is poorly understood. The scanning electron microscope (SEM) now allows observation of porosity differences in the oxides calcined from the same stone at various temperatures and times.

    The oxides formed from five limestones calcined in commercial kilns (four calcitic and one dolomitic) and one dolomitic stone calcined in a laboratory furnace were examined with the SEM, and their surface areas were determined by the Brunauer, Emmett, and Teller (BET) method using Krypton gas.

    One of the stones was subjected to several different kiln conditions. The SEM made it possible to record the changes of the low-porosity quarry stone to a very porous oxide as it was calcined. However, with increased kiln time, the resulting CaO crystals coalesce, increasing pore space, and, with continued calcination, the pore space approached zero.

    Keywords:

    roasting, calcium oxides, porosity, time dependence, temperature, electron microscopes, scanning, limestone, rocks, oxides, calcite, dolomite (minerals), tests, evaluation, kilns, refractory materials, furnaces, area, krypton, gold, palladium, dissociation, pellets, porosity, oxygen-blown converters, combustion


    Author Information:

    Eades, J. L.
    Research assistant professor and associate professorpersonal member ASTM, University of Illinois, Urbana, Ill.

    Sandberg, P. A.
    Research assistant professor and associate professorpersonal member ASTM, University of Illinois, Urbana, Ill.


    Paper ID: STP41932S

    Committee/Subcommittee: C07.02

    DOI: 10.1520/STP41932S


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