Abstract: To improve operation, particularly to allow more universal use, in which both liquid and solid crude metal, especially iron can be refined in only one reactor vessel, a reactor vessel (1) is of converter-like design with a relatively large space above a melt (7) and with slag (8) lying above said melt. For the removal of slag (8) via a closable slag channel (18'), the meltdown apparatus can be rotated about a center of rotation (20) through .+-.8.degree.. For the complete removal of the melt (7) via a closable melt channel (17') in the bottom region of the meltdown apparatus, the latter can be rotated about a center of rotation (19) through .+-.30.sup.. A magnetic coil (16) fed with direct current and arranged around the meltdown apparatus (1) serves for the magnetic damping of movements of melt (7) and/or slag (8) inside the meltdown apparatus. In the converter mode, a graphite electrode (5) used in the arc mode is replaced by a gas supply conduit, through which oxygen is then supplied under pressure.