Mineral CO₂ sequestration in alkaline solid residues

CO₂ sequestration by mineral carbonation has been recognized as a promising route for the permanent and safe storage of carbon dioxide. Various process routes have been proposed. As feedstock, calcium or magnesium containing primary minerals are used. In addition to calcium- or magnesium-containing primary minerals, suitable alkaline solid residues can be used as feedstock. The use of alkaline residues has several advantages, such as their availability close to CO₂ sources and their higher reactivity for carbonation than primary minerals. In addition, the environmental quality of residues can potentially be improved by carbonation. In this study, key factors of the mineral CO₂ sequestration process are identified, their influence on the carbonation process is examined, and environmental properties of the reaction products with regard to their possible beneficial utilization are investigated. The use of alkaline solid residues forms a potentially attractive alternative for the first mineral sequestration plants. A possibly attractive alternative is the use of suitable alkaline solid residues, such as ashes from waste incineration, demolition waste and slags from steel production.