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

Abstract

Many workers [1–9] studied the kinetics of dolomite decomposition to study the effects of different parameters like, gas (CO₂, N₂ 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^∘C. Calcite decomposed to CaO between 900 and 960^∘C and under air, simultaneous formation of CaCO₃, CaO and MgO accompanied dolomite decomposition between 700 and 740–750∘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^∘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.