Portland Cement Exhaust Characterization and Its Potential Use in Mineral Carbon Sequestration

Portland cement manufacturing produces, in its exhausts, carbon dioxide, carbon monoxide, sulphur dioxide, oxygen, nitrogen, water vapour, and argon. Significant amounts of carbon dioxide and sulphur dioxide are therefore released into the atmosphere. For the purpose of minimizing the input of greenhouse and acid rain gases, ways of capturing the carbon dioxide by, for instance, mineral carbonation, are being investigated around the world. This study is a review of the masses of gases, their volumes, temperatures, and the heat energy they release. It forms the first step in determining ways for on-site carbon dioxide and sulphur dioxide sequestration. The study shows that for a tonne of clinker, the masses of the gases produced, in tonnes, are 1.2 CO₂ (63%), 0.004 SO₂ (0.2%), 0.008 CO (0.4%), 0.0549 O₂ (2.82%), 0.5 H₂ O (25.8%), 0.16 N₂ (0.1%) and Ar 0.0028 (0.096%). The total volume of the gases leaving the stack, if the exit temperature is 300 °C, is 2.975 m³, but reaches 4.532 m³ at 600 °C, while the heat energy potentially available for downstream use, is 1272 and 1938 MJ, again at 300 and 600 °C, respectively. This is wasted heat energy that cement companies should use to capture the gases that have negative environmental consequences.