Development of a novel process for the production of calcium sulfoaluminate

In an industrial climate where the reduction of carbon emissions is paramount to meeting industry standards for a sustainable future, the cement industry is looking for alternative and creative solutions to reduce its carbon footprint and energy consumption. A collaboration between the Gulf Organisation for Research and Development, GORD, and a research group at the University of Aberdeen has
sought to develop a novel process for the production of calcium sulfoaluminate (CSA) cement, a material produced in the Chinese construction industry for use as a rapid hardening binder for 5 decades, but now undergoing rapid development into wider applications. Among other improvements, the novelty of the process lies partly in its source of sulfur. Typically, sulfur is supplied by anhydrite or gypsum in conventional raw feeds, the novel process instead
sequesters sulfur into the cement solids through the combustion of elemental sulfur. This combustion event, in turn, contributes towards the calorific value required to heat and maintain kiln temperatures by burning fossil fuel, e.g. natural gas, but without emitting CO2. The combustion of sulfur also
provides added benefits. The resultant sulfur-containing atmosphere in the kiln provides a protective environment which represses sulfur volatilisation at the operating temperatures used for CSA production, ca 1300°C. Several regimes of sulfur and oxygen partial pressures can be attained and help control clinker mineralogy. Control of the atmosphere enables preservation to ambient of belite in its reactive alpha phase which, in turn, enables bulk alumina contents of raw meals to be decreased.