Process for manufacturing a slag conditioning agent for steel desulfurization

Process for manufacturing a slag conditioning agent for steel desulfurization comprising the steps of:

• providing a slag material obtained from secondary steelmaking process, in particular a slag material obtained after an Al-killing steel process, said slag material comprising at least calcium, aluminum, iron, moisture, and a phase of calcium aluminate;
• mixing said slag material with quicklime particles having a predetermined maximum particle size, and drying said slag material by having at least a pan of the quicklime particles reacting at least partially with a moisture contained in the slag material thereby obtaining a first blend comprising slag material, hydrated lime and optionally unreacted quicklime,
• sieving said first blend at a cut-size superior or equal to said predetermined minimum particle size of said quicklime to remove a passing fraction of said first blend from a retained dried fraction of said first blend, said passing fraction having a maximum particle size lower than said cut-size and comprising a majority of said hydrated time;
• and
• mixing said retained dried fraction with a composition having an A2O3 mass fraction of at least 80 wt % relative to the weight of the composition, and collecting a slag conditioning agent having an equivalent mass ratio CaO/Al2O3 comprised between 0.55 and 1.5.