The present invention relates to a slag discharge door device for an electric furnace, wherein slag is prevented from flowing out via a slag discharge port by making a discharge control door body move up and down to and from the upper surface of a supporting body where slag is discharged by flowing to the upper surface, and the discharge of slag is controlled, such that during steel-making work in the electric furnace, the outflow of slag is prevented and heat losses are reduced, the efficiency of arc heat due to the formation of foamed slag is increased, and valuable metals are recovered from the molten slag thereby increasing the percentage of molten steel recovered.

A method of producing a foamy slag in which the projected flame produced by burning fuel, for instance methane, within an oxidant is directed onto the slag so that the flame impinges on the slag, thereby to heat the foamy slag. Carbon containing particles are entrained in the flame so that the particles are heated by the flame and are projected into the slag to form and maintain a foamy slag. The carbon containing particles can be formed of coal that contains volatiles and the carbon containing particles are resident within the flame for a sufficient length of time for the volatiles to substantially burn-off and to contribute to the heating of the particles without appreciable oxidation of carbon contained within the coal.

Bei einem Verfahren zum Herstellen einer Metallschmelze (6), insbesondere einer Stahlschmelze (6), in einem Elektro-Lichtbogenofen (1) wird die Badoberfläche (8) während der flachbadperiode(n) mit einer Schaumschlacke (9) bedeckt.

Um die Vorteile eines von Schaumschlacke umhüllten Lichtbogens über eine große Zeitspanne mit möglichst geringem Aufwand sicherzustellen, wird während einer Ofencharge mehrmals eine Pegelmessung der Schichthöhe (10) einer Schlacke durchgeführt und durch Ein- und/oder Aufblasen von Feststoffen, Gasen oder eines Gemisches von Feststoffen und Gasen in und/oder auf die Schlacke oder die Metallschmelze (6) eine einen von mindestens einer Elektrode (3) gebildeten Lichtbogen (4) einhüllende Schaumschlacke (9) gebildet, deren Schichthöhe (10) so bemessen ist, daß sich die Schaumschlacke mindestens über den gesamten Lichtbogen (4) erstreckt, so daß eine Reihe von Vorteilen optimal genutzt wird (Fig. 1).

Bei einem Verfahren zum Herstellen von Metallschmelzen, insbesondere einer Stahlschmelze aus Schrott (22), in einem Elektro-Lichtbogenofen mit mindestens einer Graphitelektrode werden zur Verringerung des Elektrodenverbrauches organische Substanzen (24, 26) in den Lichtbogen (20) durch eine zentrale Längsausnehmung (14) der Graphitelektrode (4) eingebracht (Fig. 1).

A method of melting an iron-containing cold material and simultaneously obtaining a low phosphorous and high carbon molten iron while maintaining a high post combustion rate, comprising the steps of: preparing a converter having a lance for top-blowing oxygen, and a bottom-blowing triple pipe nozzle (1) disposed at a bottom of the converter which nozzle is provided with an inner pipe (2), an intermediate pipe (3) and an outer pipe (4); supplying the iron-containing cold material into the converter in which a hot heel exists; introducing into the converter all of a carbonaceous material together with a non-­oxidizing gas through the inner pipe (2) of the triple pipe nozzle, oxygen through a space (5) defined between the inner pipe (2) and the intermediate pipe (3),and a non-oxidizing cooling gas through another space (6) defined between the intermediate pipe (3) and the outer pipe (4), and additional oxygen through the oxygen top-blowing lance so that the cold material is melted into a molten iron under an existence of slag; maintaining both the content of carbon dissolved in the molten iron at a level of 3 to 4% in most of a period of time for the melting and the rate of bottom-blown oxygen in a range of not less than 10% but less than 20% of the total amount of the oxygen; and adding intermittently or successively iron oxide into the slag in most of a melting period of time while keeping a slag basicity defined by CaO/SiO₂ in a range of 1.5 to 3.0.