Assessing the Technical Suitability of Precipitated Materials from the Electrochemical Decarbonation of Limestones for Cement and Hydrated Lime Production: A Reproducibility Study Performed in Canada and Chile

Concrete is essential for most civil engineering applications, but its use faces pressing challenges to reduce CO2 emissions. These emissions are linked principally to the chains of cement production that calcinate limestones (CaCO3→CaO+CO2) for quicklime, hydrated lime, and clinker production. Electrochemical decarbonation is a novel technology with the potential to introduce synergistic strategies to mitigate CO2 emissions from this chemical reaction. However, its early incorporation in the current chains of cement and lime production requires evidence of the quality of materials produced by this technique under the broad conditions of the cement and lime industries worldwide. In this reproducibility study performed in Canada and Chile, multiple sources of limestone feedstock used for lime and cement production were subjected to an electrochemical decarbonation process to precipitate low-CO2 intermediary feedstock materials. The potential of the precipitate materials (PMs) as an intermediary for cement manufacturing and as a final hydrated lime product was assessed by contrasting the lime saturation factor, lime concentration, content of secondary oxides (MgO, K2O, and Na2O), and content of CO2 with those of their precursor limestones and the requirements established by the state of practice of these industries. Results showed that regardless of their origin, the obtained PMs mainly comprised calcium hydroxide [Ca(OH)2>78.8% by mass], with increased lime concentration (CaO>65.39%) and decreased other primary oxides (SiO2, Al2O3, and Fe2O3<1%) and carbon dioxide content (CO2<9.42% by mass). Several PMs had suitable chemical and physical characteristics to be considered directly for clinker and lime manufacturing, which is critical to the scalability of the electrochemical decarbonation process.