Comparative Life Cycle Assessments of Laboratory and Pilot-Scale Mechanochemical Processes for Producing Carbonated Mineral Products as Cement Substitutes

The use of carbonated mineral products in cement production reduces carbon emissions and enhances durability. This study evaluated the environmental sustainability of using mineral carbonated biomass fly ash (BFA) as a partial cement replacement in European cement production. Laboratory-scale and simulated large-scale scenarios were analysed. Incorporating 20% mineral carbonated BFA showed potential for a 33% reduction in the annual Global Warming Potential (GWP) of cement products. Energy consumption factors, such as ball milling and mineral carbonation processes, were evaluated using a machine learning model and comminution flow sheet model simulations. The machine learning model predicted CO₂ absorption and energy requirements for mineral carbonation, showing greater efficiency in large-scale scenarios. Life cycle assessments consistently revealed GWP reductions for OPC-BFA mixtures, with additional emissions reductions when incorporating flow sheet modelling and machine learning data. However, the study's limitations include simplified CO₂ flue gas treatment, use of the mean EU electricity mix, exclusion of transportation impacts, and reliance on simulation data. Additionally, the cement mix exhibited reduced compressive strength. This study highlights the potential of mineral carbonated BFA to reduce cement production's environmental impact while emphasising the need for balanced optimisation between sustainability and material performance.