Effect of solidification and cooling methods on the efficacy of slag as a feedstock for CO₂ mineralization

Iron and steel making (ISM) slag is often utilized to partially offset CO₂ emissions associated with metal production. Currently, the primary recycling method for slag is as-Ca₂SiO₄ utilized in the cement industry, termed ground granulated blast furnace slag (ggbs). However, the cement market is not large enough to exploit the entirety of ISM slag as ggbs, relegating a large quantity of slag to reuse pathways with minor impacts on CO₂ reduction. Recent years have seen an increase in research into mineralizing CO₂ using the Ca and Mg content of ISM slags as a feedstock. Unfortunately, it has not been widely recognized that the solidification and cooling processes of slag dramatically effects its efficacy as a CO₂ mineralizing feedstock via modification of mineralogy, crystallinity, grain size, and micromorphology. This paper clarifies the key properties determining mineralization effectiveness and elucidates how to control these properties during the solidification and cooling process. The effect of solidification and cooling method on net CO₂ reduction is shown to be strongly dependent on solidification and cooling method along with the CO₂ intensity of energy generation..