Slag, steel and greenhouse gases

A steel mill is a logistical hub, where iron units, by-products and effluents such as CO 2 compete in terms of volume. The problematics of greenhouse gas emissions will probably strengthen these transversal relationships. For example, blast furnace slag, which is a prime secondary material for the cement industry, substitutes for CO 2 intensive raw materials such as limestone and bypasses the energy-intensive high temperature rotary kiln that is necessary to produce cement from virgin natural resources. If one is willing to view the steel mill as a co-producer of steel and slag, then one sees clearly why the greenhouse gas emissions should be shared among the two products. This is by no means an artificial viewpoint, as large reduction in emissions can be achieved by using slag as an additive to cement. The paper proposes a quantitative analysis of this issue of importance for the future.