Cement production is a major contributor to global carbon dioxide (CO₂) emissions, accounting for approximately 7% of anthropogenic CO₂ emissions worldwide. The vast majority of these emissions arise from the calcination of limestone, a key component of the cement production process. During calcination, limestone is heated to high temperatures, causing it to decompose into calcium oxide (CaO) and CO₂. Roughly two-thirds of the CO₂ emissions during cement production arise from this process, which releases large amounts of CO2 into the atmosphere. One way to mitigate the CO₂ footprint of cement production is through the capture and utilization of CO₂ emissions during the calcination of limestone. By capturing CO2 during the decomposition of limestone, cement producers can reduce their overall emissions and contribute to global efforts to combat climate change. However, the effectiveness of this approach depends on a number of factors, including the partial pressure of CO₂ during the calcination process. In recent years, a new technology has emerged for the separate calcination of limestone, which involves calcining limestone in a CO₂-rich atmosphere. This approach helps to avoid the dilution of CO₂ by combustion flue gas, enabling more efficient capture and utilization of CO₂ emissions. However, the use of a CO₂-rich atmosphere may also have an impact on the thermal decomposition of limestone, affecting the energy balance of the process. The aim of this paper is to investigate the influence of CO₂ partial pressure on the thermal decomposition of natural limestone used in cement production. A series of experiments were conducted to measure the thermal decomposition of limestone at different CO₂ partial pressures, and thermodynamic calculations were used to model the behaviour of the system. The results showed that CO₂ shifts the onset decomposition temperature of limestone to higher values, which can have a significant impact on the energy balance of the separate calcination technology.

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