Patent ID: 6946014

Claim:
A process for treating a raw steel industry slag, for conversion of said raw steel industry slag into a hydraulic binder at least equivalent to a Portland cement clinker, said raw steel industry slag containing, based on the raw steel industry slag total weight, at least 45% of CaO and less than 30% of Fe 2 O 3 , said process comprising: a) treating said raw steel industry slag with oxygen or air or a mixture thereof, at a pressure ranging from 1 to 15 bars and at a temperature ranging from 1, 650° C. to 1,400° C.; and b) adding to said raw steel industry slag before, during or after treatment step a), a lime source optionally supplemented with a silica source and/or an alumina source, the proportions of the lime source and optionally of the silica and/or alumina sources being selected such that, after conversion and at room temperature, there is obtained a final treated slag having a Fe 2 O 3 content of at least 13% by weight, a mineral composition comprising at least 40% by weight of the C3S mineral phase, and more than 10% by weight of calcium ferrite in the form of a C2F and/or C4AF mineral phase, based on the final treated slag total weight.