In the metallurgical treatment of metals, metal melts and/or slags in a metallurgical unit or melting vessel, especially in electric arc furnaces, injection devices (1) are used for blowing in or up oxygen-rich gases (6) and/or carbonaceous substances, which cause as long as possible gas jet (6') with a high pulse energy to strike to strike the surface of the slag or metal. It is known to envelope produced gas jet (6'), thereby focusing it. According to the invention, such an envelope is obtained by using a hot gas (5, 5') that is preaccelerated to such a degree that the central gas jet (6') is preferably without pulse losses.