<p>Disclosed is a slag disposal method for disposing of slags produced in furnaces during iron or steel making process. The method comprises the steps of sorting masses of crude slags obtained from the furnaces into slags rich in iron and slags not rich in iron by magnetic sorting; and applying a compressive force to the slags rich in iron so as to cause a coarse crushing and/or deformation to reduce the size and to separate the slags thus obtaining slags having increased iron content.</p>