CO₂ mineralization in slag has gained significant attention since it occurs with minimal human intervention and energy input. While the amount of theoretical CO₂ that can be captured within slag has been quantified based on slag composition in several studies, the microstructural and mineralogical effects of slag on its ability to capture CO₂ have not been fully addressed. In this work, the CO₂ uptake within legacy slag samples is analyzed through microstructural characterization. Slag samples were collected from the former Ravenscraig steelmaking site in Lanarkshire, Scotland. The collected samples were studied using X-ray Computed Tomography (XCT) to understand the distribution and geometry of pore space, as well as with scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) to visualize the distribution of elements within the studied samples. Electron backscatter diffraction (EBSD) was used to study the minerals distribution. The samples were also characterized through X-ray diffraction (XRD) and X-ray fluorescence (XRF), and the amount of captured CO₂ was quantified using thermogravimetric analysis (TGA). Our results demonstrate that CO₂ uptake occurs to the extent of ∼9–30 g CO₂/ kg slag. The studied samples are porous in nature, with pore space occupying up to ∼30% of their volumes, and they are dominated by åkermanite-gehlenite minerals which interact with the atmospheric CO₂ slowly at ambient conditions. EDS and EBSD results illustrate that the precipitated carbonate in slag is calcite, and that the precipitation of calcite is accompanied by the formation of a Si-O-rich layer. The provided analysis concludes that the porous microstructure as well as the minerals distribution in slag should be considered in forecasting and designing large-scale solutions for passive CO₂ mineralization in slag.

矿渣中的CO ₂矿化受到了广泛关注，因为它在人为干预和能量输入极少的情况下发生。_{虽然在一些研究中已经根据炉渣成分量化了炉渣中理论上可以捕获的CO 2}量，但是炉渣对其捕获CO ₂能力的微观结构和矿物学影响尚未得到充分解决。在这项工作中，通过微观结构表征分析了遗留炉渣样品中CO _{2的吸收。}炉渣样品是从苏格兰拉纳克郡的前拉文斯克莱格炼钢厂采集的。使用 X 射线计算机断层扫描 (XCT) 对收集的样品进行研究，以了解孔隙空间的分布和几何形状，并使用扫描电子显微镜 (SEM) 结合能量色散 X 射线光谱 (EDS) 来可视化分布研究样品中的元素。电子背散射衍射（EBSD）用于研究矿物分布。_{还通过X射线衍射(XRD)和X射线荧光(XRF)对样品进行了表征，并使用热重分析(TGA)对捕获的CO 2}的量进行了定量。我们的结果表明，CO _{2 的}吸收量约为 9–30 g CO ₂ / kg 炉渣。研究的样品本质上是多孔的，孔隙空间占其体积的~30%，并且它们以阿克锰长石-钙黄长石矿物为主，在环境条件下与大气中的CO ₂缓慢相互作用。EDS和EBSD结果表明，炉渣中沉淀的碳酸盐是方解石，方解石的沉淀伴随着富Si-O层的形成。_{所提供的分析得出的结论是，在预测和设计炉渣中被动CO 2}矿化的大规模解决方案时，应考虑多孔微观结构以及炉渣中的矿物分布。