Evolution of the pore structure as a result of mineral carbonation of basalts from Poland in the context of accumulation and permanent storage of CO2

Abstract

The aim of the work was to identify the basic structural properties of basalts from the Central European Volcanic Province in Poland in the context of assessing the possibility of permanent CO₂ storage. The research was carried out on rock samples from three Polish basalt mines. An experiment on the reactivity of minerals contained in basalt was carried out in the original geochemical reactor. In an isolated system with a capacity of 100 cm³, proper analyzes of mineral carbonation were carried out for 65 days at a temperature of 293 K and a pressure of 0.43 MP. The pressure, pH and temperature of the process were recorded. The mechanism of structural changes that occurred in pores of different diameters was determined. SEM microscopic analyzes showed a transformation of the macroporosity and morphology of the sample. The formation of new voids and transport channels was observed, which resulted from the partial dissolution and conversion of minerals. At the same time, the pore surface area in the transitional pores and finest micropores has been reduced, indicating that the surface area of these pores have been overbuilt and the tight intrapore transport pathways have been clogged. The gravimetric measurements of the sorption capacity of basalt in relation to gaseous CO₂ were also conducted. After the mineral carbonation process, the efficiency of CO₂ accumulation decreased, which confirmed that the previously free pore space had been filled. Comprehensive scanning, structural and sorption studies confirmed the migration and multi-track transformation of minerals from basalt.