Abstract

Mineral carbonation of steel slags has shown potential as a viable option for carbon capture, utilisation, and storage. This process not only valorises both steel slags and the carbon emissions generated during steel production, but also offers an interesting agricultural application. Carbonated steel slags can serve as substitutes for liming agents or basalt rock powder, and, even when used in agriculture, they continue to capture carbon dioxide throughout their use phase. To ensure that the carbon dioxide captured during the mineral carbonation process exceeds the emissions generated by the process, a life-cycle assessment is necessary. This life-cycle assessment must incorporate the temporal aspects to monitor emissions and sequestration over time, which is critical for evaluating carbon capture, utilisation, and storage technologies. Additionally, including the temporal aspect helps determine whether mineral carbonation is essential, allowing comparison of the carbon dioxide captured during both the production (carbonation) and use phases of both carbonated and non-carbonated slags in agriculture. To address this gap, this study proposes an integrated environmental life-cycle assessment combined with a dynamic life-cycle assessment to track emissions and sequestration over time. This approach enables the visualisation of time-dependent radiative forcing and the cumulative carbon dioxide capture throughout both the production and use phases of carbonated slags. The study utilises empirical data collected from the AgriCarb project, funded by the Research Foundation Flanders. This project includes steel slag carbonation and emissions measurements over 435 days to demonstrate the proposed integrated conventional and dynamic life-cycle assessment framework. At the time of writing this abstract, no known studies have applied dynamic life cycle assessment to a carbon capture, utilisation, and storage case study, making this research novel and the first to demonstrate such a framework in this context. Preliminary results from the assessment show that carbonated slags sequestered more carbon dioxide over the 435 days, combining sequestration from both the carbonation process and the agricultural use phase, compared to non-carbonated slags. The findings quantitatively demonstrate the environmental benefits of mineral carbonation. This integrated framework offers a practical, quantitative approach to evaluating mineral carbonation of steel slags as a carbon capture, utilisation, and storage technology and provides a valuable tool for future assessments of other technologies in these fields.