On the Crystals of CaO In Limestone Calcined at Different Temperatures

We calcined six kinds of limestone from various localities up to 900, 1000, 1100, 1200, 1300 and 1400°C with or without NaCl, and observed the growth of CaO crystals in their thin sections. The CaO crystals occurring in the specimens calcined with NaCl are, as usual, better grown than those without NaCl, and it is more evident at lower temperature calcination. In the case of higher temperature calcination, the formers are hardly over-burnt.With regard to the limestones, those of cryptcrystalline make finer CaO crystals. Especially it is evident at higher temperature calcination. This may show to have larger range for optimum calcination, that is easy to work with.