Dolomite thermal behaviour: A proposal to establish a definitive decomposition mechanism in a convective air atmosphere

Abstract

In this research, the thermal behaviour of two dolostone samples of Argentine origin has been studied. First, a physicochemical characterization of the raw materials was carried out, determining their chemical and mineralogical composition. The thermal response of the materials was evaluated using TGA, DTA, muffle calcination, XRD and FTIR techniques. The thermal tests consisted of calcination schedules at temperatures and times of 750 °C in 1 and 3 h and 950 °C in 1, 3 and 4 h. With all these tests, the mechanism of thermal decomposition was established, taking as principle that a reaction mechanism must be coincident with all the experimental data. The results of the experiments indicate a three-stage reaction mechanism, the first stage being a high entropy process that, according to free energy calculations, this mechanism is more satisfactory than the current decomposition mechanism in calcium and magnesium carbonates separately.

Keywords

• Thermal behaviour
• Dolomite
• Dolostone
• Thermal decomposition
• Reaction mechanism
• Entropy