Abstract: Metallurgical melting and refining unit (21) with which scrap steel, sponge iron, solid and molten pig iron can be processed in any desired ratio of admixture, and coal, oil, gases or electrical power can be used as energy source. For this purpose, and with an eye to low investment costs, the furnace vessel (22) is made in the form of a round hearth furnace with a ratio of the inside dimensions diameter (d) to height (h) of the furnace vessel between 0.8 and 2.5, and one tuyere bench (33) is provided on each side of the tap hole (10), for primary tuyeres which discharge below the melt surface. Furthermore, two tuyeres (25) discharge into the furnace vessel above the melt surface and are constructed as burners. The charge material can be preheated and charged in a controlled manner by a scrap preheater (27) whose floor consists of gas-permeable grate parts (30, 31) which can be opened from the center. (FIG.