Techno-economic assessment of calcium sulfoaluminate clinker production using elemental sulfur as raw material

Abstract

The foreseen decarbonisation of the cement industry by 2050 will require a combination of different measures in the current manufacturing practices such as the improvement of the energy efficiency, the use of alternative fuels, the reduction of the clinker to cement ratio, and the integration of carbon capture, especially beyond the year 2030. The production of alternative binders, for the substitution of the current product families of cement, is under investigation due to its significant potential in emissions reduction, although robust and agreed life cycle assessment methodologies are still claimed by the industry in this field. Calcium sulfoaluminate (CSA) cements appear as a promising alternative to Portland cements due to the significant reduction of the direct emissions of carbon dioxide caused by the lower need of limestone and fuel. However, they require sulfate and higher inputs of aluminium oxide, sourced from bauxite. This study focuses on the techno-economic performance, in the geographical scope of Qatar, of a novel CSA production method consisting of the combustion of sulfur to supply SO3/SO2 to the clinkering reaction. This new approach is proven to reduce the associated greenhouse gases emissions of Portland cement clinker production, while, in general, CSA clinker production costs are higher than those for Portland cement clinker. Nevertheless, CSA has a competitive CO2 avoidance cost, provided that the economics of raw materials supply, such as bauxite, favours its production; an aspect that is further emphasised in a prospective analysis towards more restrictive climate policies.