||Sintering of Nascent Calcium Oxide.
Borgwardt, R. H. ;
||Environmental Protection Agency, Research Triangle Park, NC. Air and Energy Engineering Research Lab.
Calcium oxides ;
Air pollution control ;
Surface chemistry ;
Reaction kinetics ;
Mathematical models ;
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The paper discusses the measurement of the sintering rate of CaO in a nitrogen atmosphere at temperatures of 700-1100 C. CaO prepared from ultrapure CaCO3 was compared with an impure CaO derived from limestone. Both materials yielded an initial surface area of 104 sq m/g. The rate of surface reduction was independent of particle size between 2 and 20 micrometers, but strongly dependent on temperature and impurities. A model was used to correlate the kinetics of surface reduction and identify lattice diffusion as the mechanisms of solid transport. Impurities increased the rate of sintering at a given temperature and reduced the activation energy. The porosity declined logarithmically with time during the intermediate stage of sintering.