Study of kinetic characteristics of limestone decomposition under different atmospheres and heating conditions

Abstract

Decomposition tests on limestone were carried out under isothermal and non-isothermal experimental conditions in 21%O2/79%N2 and 21%O2/79%CO2 atmospheres. The decomposition properties and kinetics of limestone in different atmospheres and under different heating conditions were explored. The results show that different atmospheres and heating conditions can both affect the decomposition properties and kinetics of limestone. Under non-isothermal conditions, the activation energy of limestone decomposition shows an initially increasing and then decreasing trend with the increase of conversion in both atmospheres. Under isothermal conditions, the activation energy of limestone decomposition increases slightly and then decrease with the increase in conversion in 21%O2/79%N2 atmosphere, while the activation energy decreases monotonically with the increase IN conversion in 21%O2/79%CO2 atmosphere. Heating conditions exert no obvious effect on the decomposition mechanism. In both atmospheres, limestone decomposition process is governed by random nucleation and nucleus growth. Limestone decomposition follows the three-dimensional model (n = ¾) more likely in 21%O2/79%N2 atmosphere, while it follows the two-dimensional model (n = ½) more likely in 21%O2/79%CO2 atmosphere.