A Method for the recovery of the secondary metallurgy (LF) slag from a plant for the production of steel, the method comprising a cooling step of the slag, by means of the passage of air and/or other gas, a breakdown step, a step of extracting the powder, wherein the breakdown step is accelerated by means of forced convection of a cooling fluid and/or another reaction, gas and by means of moving the slag mass by overturning and vibrating support gratings. The overturning and vibrating support gratings are provided inside closed metallic boxes which are connected in series and closed with movable containment partitions to form a treatment module. The breakdown, step is accelerated by means of overturning the slag mass from the support grating of one metallic box to the support grating of an adjoining box.