Method of continuous manufacturing of solidified steelmaking slag and associated device

A method of continuous manufacturing of solidified steelmaking slag comprising the steps of:

• solidifying molten steelmaking slag including at least 2% in weight of free lime so as to produce solidified slag particles having a diameter below 1 mm, the molten steelmaking slag being put in contact with at least a first carbonation gas during such solidification;
• and
• cooling the solidified slag particles down to a temperature below or equal to 300° C., in a closed chamber, the solidified slag particles being put in contact with at least one second carbonation gas during such cooling, wherein the second carbonation gas includes at least 25% in volume of CO2, between 5 and 30% in volume of CO, between 1 and 55% in volume of H2, between 1 and 55% in volume of N2, and between 1 and 5% in volume of O2.