Molten salt synthesis of compounds related to cement

Producing compounds related to cement in a molten salt flux system offers a reduction in CO 2 emissions from the cement industry by allowing target compounds to be produced at lower temperatures than those in their respective conventional manufacturing processes. A thermodynamic study presented here provides the theoretical minimum formation temperature of cement related phases and infers that molten salt synthesis could potentially obviate the need for the traditionally employed “high” temperature furnaces. Laboratory experiments have been carried out to test the thermodynamic predictions. Spurrite is found to form readily in a molten salt flux, and its inherent stability may inhibit the production of other compounds in low melting point fluxed
systems containing CaCO3 . Ferrites are also readily produced in molten salts at temperatures of ≈850°C; however, the A:F ratio varies from those found in conventional Portland cement clinkers, i.e. ≈0.3:1.7 rather than ≈1:1.