Mineral carbonation is a carbon utilisation technology in which an alkaline material reacts with carbon dioxide forming stable carbonates that can have different further uses, for instance as construction material. The alkaline material can be a residue from industrial activities (e.g. metallurgic slags) while CO₂ can be recovered from industrial flue gasses. Mineral carbonation presents several potential environmental advantages: (i) industrial residues valorisation, (ii) CO₂ sequestration and (iii) substitution of conventional concrete based on Portland cement (PC).

However, both the carbonation and the CO₂ recovery processes require energy. To understand the trade-off between the environmental benefits and drawbacks of CO₂ recovery and mineral carbonation, this study presents a life cycle assessment (LCA) of carbonated construction blocks from mineral carbonation of stainless steel slags. The carbonated blocks are compared to traditional PC-based concrete blocks with similar properties.

The results of the LCA analysis show that the carbonated blocks present lower environmental impacts in most of the analysed impact categories. The key finding is that the carbonated blocks present a negative carbon footprint. Nonetheless, the energy required represents the main environmental hotspot. An increase in the energy efficiency of the mineral carbonation process and a CO₂ valorisation network are among the suggestions to further lower the environmental impacts of carbonated blocks production.

Finally, the LCA results can promote the development of policy recommendations to support the implementation of mineral carbonation technology. Further research should enable the use of mineral carbonation on a broader range and large volume of alkaline residues.

矿物碳酸化是一种碳利用技术，其中碱性材料与二氧化碳反应形成稳定的碳酸盐，这种碳酸盐可能具有其他用途，例如用作建筑材料。碱性物质可能是工业活动（例如冶金渣）的残留物，而CO ₂则可以从工业烟气中回收。矿物碳酸化具有几个潜在的环境优势：（i）工业残渣平衡，（ii）CO ₂隔离和（iii）替代基于波特兰水泥（PC）的常规混凝土。

然而，碳酸化和CO ₂回收过程均需要能量。为了了解在CO ₂回收和矿物碳酸化的环境利弊之间的权衡，本研究提出了由不锈钢炉渣矿物碳酸化而产生的碳酸化建筑砌块的生命周期评估（LCA）。将含碳酸盐块与具有类似性能的传统PC基混凝土块进行比较。

LCA分析的结果表明，在大多数分析的影响类别中，碳酸盐岩块对环境的影响较小。关键发现是，碳酸化嵌段呈现负碳足迹。尽管如此，所需的能源还是主要的环境热点。建议进一步提高碳酸盐砌块生产对环境的影响，其中包括提高矿物碳化过程的能源效率和CO ₂增值网络。

最后，生命周期评估的结果可以促进政策建议的制定，以支持矿物碳酸化技术的实施。进一步的研究应能使矿物碳酸化作用在更广泛的范围内和大量的碱性残留物中使用。