Carbonation of quicklimes during cooling in moderate and high CO2 atmospheres

Four limestones were calcined in atmospheres containing moderate ( ∼ 30%) and high ( ∼ 100%) CO 2 levels, and the carbonation characteristics of the quicklimes during cooling in these atmospheres were studied using thermogravimetric analysis. The carbonation rates, extents, and onset temperatures varied depending on the atmosphere and parent limestone type. Scanning electron microscopy showed that the quicklimes produced from sedimentary limestones exhibited larger pores and thicker structures, especially after calcination in the high CO 2 atmosphere. The quicklimes produced from metamorphic limestones exhibited smaller pores among finer structures, with no major observed differences due to the different calcination atmospheres. However, the carbonation extents differed more in the quicklimes produced from metamorphic limestones after calcination in the different atmospheres, and their carbonation rates were also generally higher. Pore filling was observed in all carbonated quicklimes. Practically, the results indicate significant carbonation of all the tested quicklimes when cooling is conducted in atmospheres containing moderate or high levels of CO 2 . This has ramifications for processes where such conditions can occur, especially if excessive carbonation is unacceptable; e.g., in the cooling zone of electrified lime-based production kilns. • Quicklime carbonation behaviour depended on conditions and parent limestone type. • Differences in carbonation onset temperature and final extent of carbonation. • Quicklimes derived from metamorphic limestones generally carbonated more. • Larger pores in quicklimes from sedimentary limestones; fine pores from metamorphic. • Pore filling and morphological changes observed in quicklimes due to carbonation.