Effect of compaction on the kinetics of thermal decomposition of dolomite under non-isothermal condition

摘要

Many workers [1-9] studied the kinetics of dolomite decomposition to study the effects of different parameters like, gas (CO2, N-2 etc.) pressures, water vapor, presence of other impurities, particle size and grain size of the dolomite samples, crystallinity etc. on the decomposition kinetics of dolomite using different tools like, thermal analysis, thermo-gravimetric analyses, XRD technique etc. and different values of the activation energies for the decomposition reaction, order of reactions have been reported. It has been observed that pure dolomite decomposed in only two steps. The first stage of the thermal decomposition of dolomite resulted in the formation of Mg-calcite [(CaMg)CO3] and periclase (MgO), with the liberation of CO2. It was further observed that under CO2, dolomite decomposed directly to CaCO3, accompanied by the formation of MgO between 550 and 765 degrees C. Calcite decomposed to CaO between 900 and 960 degrees C and under air, simultaneous formation of CaCO3, CaO and MgO accompanied dolomite decomposition between 700 and 740-750 degrees C. At the latter temperature, the calcite began to decompose even though a significant amount of dolomite was still present and simultaneous decomposition of the two carbonates was terminated at 780 degrees C. Also, changes in decomposition rates of the various phases correlated with changes in the rate of weight loss determined by derivative thermo-gravimetric analysis. (c) 2005 Springer Science + Business Media, Inc.