The 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 reducing its carbon footprint and energy consumption. The title review develops 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 change.

The novelty of the proposed process lies partly in its source of sulfur. Typically provided by 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. The combustion of sulfur also provides various added benefits. The resultant sulfur-containing atmosphere in the reaction system provides a protective environment which represses S volatilisation at the operating temperatures used for CSA production, ca 1200–1300 °C.

The novel process was developed with the intention for eventual commercial production in Doha, Qatar. The combustion of sulfur would be additionally beneficial due to the nation’s production of vast quantities of natural gas; elemental sulfur is a by-product of the Claus process, used for the desulfurisation of natural gas or sour crude. The proposed novel process would thereby utilise a waste product, i.e. sulfur, for the production of a low carbon cement product.