At the production of the secondary steel based on scrap, wherein the scrap (10) is fed in a scrap preheater (2) through a charging device (1), is preheated there and, finally, is brought into a smelting unit (3) and is melted there with primary energy only, the process gases (19), which leave the smelting unit (3), are not used any more for directly preheating the scrap (10) but are rather used indirectly by heating a gaseous preheatable medium, e.g., air (18) or inert gas, whereby energetic, fluidic, and spatial decoupling of preheating and melting and of post-combustion and preheating is achieved.