Alternative energy sources are not the sole answer to reduce the carbon dioxide emissions from the building materials sector. That is because big part of the greenhouse gas emissions from cement plants comes from the calcination of the raw materials inside the cement kiln and not from burning fuels. To further reduce those carbon dioxide emissions, it is necessary to develop solutions for capturing the gas. Those solutions are called carbon capture and utilizations processes. A vital part of those CCUS-Processes are carbonation reactions. Their goal is to capture carbon dioxide in chemically stable compounds like carbonates which can be deposited or used profitably. One way is to treat mineral compounds at temperatures around 80 °C and elevated carbon dioxide partial pressure. The resulting products have good properties for deposition in landfills. Indirect carbonation on the other hand extracts the reactive chemical compounds like CaO and MgO in different extracting agents. Those indirect processes make it possible to produce clean carbonates which can be used by the paper industry or the pharmaceutical industry. Carbonation experiments, carried out in a batch-reactor, show that a CO2 uptake of 150-300 kgCO2/tDust for bypass dust and 180 kgCO2/tAsh for fly ash is possible. The carbonation potential of bottom ash (70 kgCO2/tAsh) and old cement fines (20 kgCO2/tFines) is noticeably lower.