Slag as a Raw Material: Assessing the Economics

Using slag as a raw material is not a new concept. Recently its use has become more prevalent as plants look to reduce CO₂ emissions. Because the calcium in slag exists as CaO, the use of slag as a raw material reduces CaCO₃, and the CO₂ emissions per ton of clinker production are reduced. It´s this reduction in CO₂ emissions per ton of clinker production which allows plants that are fan limited to produce more clinker, or to allow any plant to produce the same amount of clinker with lower CO₂ emissions. Slag as a raw material is often first viewed negatively since it usually increases the raw materials cost. However, since slag can lead to increased clinker production, the total manufacturing cost can be decreased. Furthermore, overall profits will improve provided the plant has sufficient grinding capacity to mill the additional clinker, and a need for additional cement sales. Several examples are given.