New Insight into Energy-Saving Calcination of Limestone: Preparation, Characterization, and Application of Partially Calcined Limestone

This study presents an energy-saving calcination strategy using low temperatures and a controlled heating process for preparing partially calcined limestone. The low temperature and controlled heating ensure the high activity of the porous oxide and significantly reduce CO2 emissions and energy consumption. Reactants and products coexist in partial calcination to form a core-shell structure. Furthermore, the decarbonization of limestone is observed by multiple characterizations and interpreted visually. The prepared partially calcined limestone was used as a precursor for the cementitious materials. The compressive strength of cementitious materials with partially calcined limestone was significantly enhanced because of: (1) the increased activity of calcium oxide and (2) the presence of in situ nuclei. This is further demonstrated by the accelerated reaction heat release from the isothermal calorimetry test and the microstructure analysis. The challenges of partial calcination technology and its expanding applications are also highlighted.