A consecutive decomposition–sintering dilatometer method to study the effect of limestone impurities on lime microstructure and its water reactivity

Immersion Calorimetric Method to Study Lime Surfaces Impurities and Particles Aggregate Morphologies

“…Those data cannot be extrapolated to infer that a similar role is played by the impurities of the mineral rocks in controlling the lime microstructure evolution during the thermal decomposition. In fact the impurity contents in the limestone matrix are very low in the average, but at the calcite grain boundaries their local concentration can be very high, and they can form small island and intrusion of minerals different from the host calcite [1]. Nevertheless the high wt% content of Al2O3 and SiO2 in the LMST1 and LM1 samples , on account of the effect that these oxides have on the lime particle properties, are a signal that the LM1 particles might have chemical and physical properties different from those of other limes.…”

“…These morphological changes, cannot be due only to the effects of the LMST1 decomposition temperature. Indeed, when lime grains evolve from a round and/or polyhedrical shape to a flat one, others high temperature processes must occur [1], beside the ones due to the gas-solid reaction associated with the escaping CO2 [7,35]. Fig.…”

“…In a previous paper [1], we developed a consecutive decomposition-sintering dilatometer method (CDSD) to study the effect of impurities on the lime microstructures formed during the decomposition of limestone in air. It had been proven that at temperatures from 700-1200°C, the grains of CaO-based limes can have different morphologies as a consequence of the thermodynamic and kinetic features of the calcium carbonate decomposition processes [2][3][4].…”

A Kinetic Study of Thermal Decomposition of Limestone UsingIn SituHigh TemperatureX‐Ray Powder Diffraction

“…At present, the influence of the limestone features (i.e., the types and quantities of impurities, degree of calcite crystallinity, microstructure, etc.) on calcination is still difficult to predict, owing to the complexity of the thermal processes that occur during limestone decomposition . As a whole, a great deal of variability exists in the reported values for the decomposition temperatures, activation energies, and rates of decompositions …”

“…4,5 The decarbonation process is a heterogeneous reaction which depends, on the one hand, on the physico-chemical features of the starting material and on the experimental conditions on the other. [6][7][8] In particular, the temperature and rate of calcination are influenced by the partial pressure of carbon dioxide in and around the sample, by the presence of impurities and by the size (and the presence of cracks) in calcite grains. The associated minerals and microstructure (or texture) also influence the activation energy for dissociation of carbonates.…”