Mineral Trapping of CO2 for Cement Industry De-Carbonization

Mineralization of gaseous carbon dioxide by alkaline industrial waste, as sorbents, is a promising carbon capture and storage method. The Estonian energy sector is based on local oil shale. In addition to substantial CO2 emissions, the latter is connected with the formation of huge amounts of ash. Retention capacity of this ash is about 0.1 t of CO2 per t of ash.

In addition, concrete demolition wastes, specifically the fine fractions rich in calcium hydroxide and calcium silica hydrate, is considered to be good sorbents for CO2 sequestration, forming also thermodynamically stable calcium carbonate (CaCO3). The objective of the research is to study burnt oil shale and concrete demolition wastes as sorbents in CO2 mineralization process in order to identify the most promising materials for CO2 capture as well as to specify reaction kinetics and operating parameters for a scale up. Results indicated that selected types of burnt oil shale could be used as effective binders in the proposed CO2-mineralization system. The CO2 uptake was mainly attributed by the free lime content, which is relatively high (10-15%) in burnt oil shale, but nonexistent in concrete demolition wastes. A kinetic model was built to predict the composition of solid and gas phase at given operating conditions. The re-carbonated materials could in turn be used in concrete application, so the CO2 captured from the Ca-looping installation in Vernasca Cement Plant could be trapped and utilized in the same plant.