Direct Aqueous Carbonation of Primary and Secondary Raw Materials

A wide range of Carbon Capture, Utilization and Storage (CCUS) technologies is available for reducing CO2 emissions. One of the potential options is the mineral carbonation of primary and secondary feedstocks, particularly in industrial operations where suitable materials are already available as by-products. In this process, CO2 can be converted into a solid form through reactions with metal oxides present in the solid material, resulting in its permanent binding as carbonates. The thesis deals with the investigation of primary and secondary materials suitable for mineral carbonation, with a particular focus on their mineralogical composition and properties. In addition, the process engineering perspective is taken into account with regard to reactor parameter and design optimization. The aim is to identify and optimize the key parameters influencing reaction kinetics and CO2 uptake in order to maximize process efficiency and thereby contribute to the development of a process that may be economically viable in the future. The experimental approach of this research comprises two main test series and a complementary study, aimed at systematically investigating the carbonation behavior of selected materials under controlled conditions. The effects of temperature, pressure, solid content, the use of additives, and reaction time on CO2 uptake are evaluated through the targeted variation of these parameters. Furthermore, through the comparison of materials with varying reactivity, important factors associated with chemical and mineralogical composition, material behavior during carbonation, and process design are determined, offering insights into their effects on carbonation efficiency. In addition to the experimental work, a detailed mass and energy balance was conducted in order to assess the process from the perspective of resource and energy efficiency. The balance is based on the findings of the experimental series. The analysis emphasizes the importance of efficient process design and, specifically, points out the high energy demand of the pretreatment step.