Utilization method of ultra-low carbon steel casting residual direct return steel ladle

The invention relates to a utilization method of an ultra-low carbon steel casting residue direct return steel ladle. The method comprises the following steps that 1, the converter blowing end point molten steel temperature is larger than or equal to 1660 DEG C, the blowing end point [C] is 0.02%-0.06%, it is ensured that the temperature is larger than or equal to 1620 DEG C when molten steel enters a furnace rear argon station, a sliding plate or a slag stopping plug is adopted for stopping slag in the steel tapping process, and the thickness lt of a steel ladle slag layer is controlled; the clearance of the steel ladle is greater than 400mm; 3, transferring the molten steel to an RH (Ruhrstahl Heraeus) and carrying out vacuum decarburization treatment, 4, deslagging before casting residues: after large ladle pouring is finished, hoisting the large ladle casting residues to a slag overturning position by using a travelling crane, 5, blending the deslagging casting residues into the next furnace of full molte