On the road to net zero-emission cement: Integrated assessment of mineral carbonation of cement kiln dust

Climate change mitigation entails reaching net-zero emissions, which in turn requires unprecedented actions in all aspects of society. These include the cement industry, which represents 7% of global CO2 emissions. A proposed option for reducing CO2 emissions in the cement industry is the use of CO2-containing flue gas and cement kiln dust (CKD) for producing mineral carbonates that serve as non-reactive fillers for blending cement. This work proposes the mineral carbonation of CKD (MCCKD process) to convert CO2 to synthetic carbonates and analyzes under which conditions the MCCKD process can be a promising concept for the cement industry in Colombia. For this purpose, an existing conventional cement plant (base case) is compared with a hypothetical cement plant with MCCKD. Both systems are compared in an integrated techno-economic and environmental assessment and in eight emission scenarios with no full-abatement (NA) and full-abatement (FA) parameters, assuming a conventional energy mix and a renewable energy mix. Key findings show that implementing the MCCKD process increases by 27-30 % the cost of goods manufactured (COGM) for a 7-8% reduction in CO2 emissions for fossil and renewable scenarios, respectively, in the NA scenario. In contrast, the FA scenarios result in a reduction of COGM by 13-14 % for fossil and renewable scenarios. The evaluation supports the economic feasibility of implementing the MCCKD within a conventional cement plant from a net-zero emissions perspective, with total CO2-captured costs ranging from 37.2 to 43.9 USD/t CO2-captured (FA). The analysis shows that the MCCKD process, combined with transport and storage with renewable energy sources, has significant economic and environmental advantages compared to the same process based on fossil energy sources.