Relationship between microstructure of carbonate rocks, calcite crystallinity and decarbonisation process during lime burning

Abstract

The use of limestone in lime and clinker production respectively represents one of the biggest industrial branches worldwide. Decarbonization is a crucial part of the burning process. No clear prediction method of the decarbonisation heat for a particular limestone, even in a relative scale, has been published yet. In the presented research, ten diverse very pure limestone samples from neoproterozoic up to cretaceous were studied by means of light microscopy, powder XRD and differential scanning calorimetry. The samples showed similar mineralogical compositions and relatively close calcite crystallinity including mean crystals size, but very different microstructures and the crystals sizes. DSC was used to measure and compare the heat of different limestones decarbonisation. With the exception of three samples with extremely dense or coarse microstructure, a strong correlation of 0.95 according to the Pearson test between mean size of calcite crystals and the value of the decarbonisation heat was found.