Methodology of sample selection for study of limestone decarbonation

Abstract

Depending on nature of calcination process, we expect to get lime with specific features, for example fast or slow reactivity, certain grain size or lime that provides hydrated lime with high specific surface area. However, reality is often completely different. Because of that, there are dozens of works in past 70 years that tried to find correlation between properties of limestone, calcination parameters and final properties of hydrated lime. None of these papers has managed to find such a relation in general sense. Our work on this subject starts with proper sample selection. In order to contain the widest range of samples, we selected only limestones with high purity. All the samples have content of CaCO3 over 97.8 %. Sample file contains specimens with various geological age (form 60 mil. to 500 mil. years old), various physico-mechanical properties and different petrology. These samples are complemented with some limestones with unexpected behavior during calcination process. Rationale behind selection of each sample is included. We ended up with 26 samples of limestones. These samples were in first phase analyzed using chemical analysis, mineralogical analysis of insoluble residues and many others to identify differences in behavior. The results showed differences in the porosity and the associated volumetric mass density. Mineralogy of insoluble residue was in all cases very similar, so it is not cause of difference in behavior. This means that there are many other factors left for assessment of effect on behavior of lime, hydrated lime and also limestones during burning process.