Abstract: A system for metal powder atomization comprising a refractory lined melting furnace (1) configured to melt metal into a liquid metal bath (6), in which furnace (1) a drain (3) is arranged for draining liquid metal from the bottom of the furnace. The drain (3) is configured to be closed by a stopping member. The system comprises an atomization chamber (2) configured to receive and atomize liquid metal from the melting furnace (1). The system also comprises removal means controllable from the bottom region of the furnace (1) for removing the stopping member without interfering with the surface of the liquid metal bath (6). The removal means and the stopping member are configured such that the stopping member is removable independently of the temperature of the liquid metal bath (6) using the removal means.

Abstract: A method and apparatus for forming internally shrouded supersonic coherent jets comprising an inert gas, such as pure argon and argon/oxygen mixtures. This method and apparatus can be employed to produce low-carbon steels with a top lance in basic oxygen steelmaking.

Abstract: A multifunction injector (10, 11, 12) comprising a De Laval nozzle (20) adapted to act as a burner at subsonic or supersonic speed, combined with a plurality of nozzles (31, 32) for fuel and comburant respectively, arranged in two rings, concentric and co-axial to said De Laval nozzle (20) and externally protected by a specifically shaped protection cavity (40).

Abstract: A method of introducing a solid particulate reagent into a bath of metallurgical liquid comprises a step of introducing a solid particulate reagent into a main supersonic gas jet. The main supersonic gas jet is directed at the surface of the bath and is surrounded with a jet of shrouding gas, preferably of a burning hydrocarbon fluid fuel, provided at a supersonic velocity. The main supersonic gas jet is formed at a velocity which is in the range of minus 10% to plus 10% of the velocity at which the jet of shrouding gas is formed, preferably in the range of Mach 2 to 3.

Abstract: A method for the regeneration of residues containing sulphur is characterized in that a droplet stream containing fuel is introduced into the reactor simultaneously with the droplet stream containing the residue and is fed into a pre-reaction zone that is created by feeding in an oxygen-rich gas stream, whereby the residue in the pre-reaction zone is partially thermally cleaved and subsequently fed into the reaction zone.

Abstract: A method of injecting oxygen into a melt located within a metallurgical furnace having a heated furnace atmosphere in which oxygen and fuel is injected into 1 or more nozzles having passageways of converging-diverging configuration under choked flow conditions to produce supersonic jet or jets discharged from the passageways. Fuel is injected into internal circumferential locations of the passageways so as to impart a structure to the jets being discharged that have an outer circumferential region containing a mixture of fuel and oxygen and a central region containing essentially oxygen. Such a structured jet upon discharge interacts with the furnace atmosphere to create an outer shear-mixing zone in which the outer circumferential layer mixes with the heated furnace atmosphere and auto-ignites to produce a flame envelope surrounding a supersonic jet of oxygen. The jet of oxygen and flame envelope can be directed against a melt contained within the metallurgical furnace for injection of oxygen into the melt.

Abstract: A multifunction injector (10, 11, 12) comprising a De Laval nozzle (20) adapted to act as a burner at subsonic or supersonic speed, combined with a plurality of nozzles (31, 32) for fuel and comburant respectively, arranged in two rings, concentric and co-axial to said De Laval nozzle (20) and externally protected by a specifically shaped protection cavity (40).

Abstract: A method for operating a vacuum vessel with a coherent jet wherein vacuum conditions are established within the vessel and an anchored or attached flame envelope resulting from subsonic velocity fuel and oxidant is provided around at least one supersonic gas stream.

Abstract: The electric arc furnace is equipped with a supersonic injector comprising a so-called Laval nozzle arranged at a certain distance above the bath. The dimensions of the nozzle are calculated as a function of the desired flow rate of oxygen and the desired velocity of the jet, and the pressure of the oxygen at the intake of the nozzle is such that the static pressure of the jet at the exit of the injector is substantially equal to the pressure of the surrounding atmosphere. Preferably, the injector comprises an annular channel for injection of natural gas, and can be used in burner mode at the start of the melting of scrap iron. The velocity of the oxygen is then subsonic.

Abstract: A first quick-coupling part can be brought into interaction with a second quick-coupling part via an interaction portion. The quick-coupling parts are held together with locking members. The interaction portion is designed with a surface layer which brings about an essentially crack-free flexibility for the locking members in spite of high actuating forces. One or more underlying layer(s) has (have) greater hardness than the surface layer, and the combination of said layers gives the necessary resistance against high media pressure.

Abstract: A process and apparatus for processing a shredder light fraction including multi-duct nozzle having at least an end section positionable within a metallurgical vessel containing a molten metal bath. The shredder light fraction may be fed into the molten metal bath while using only small quantities of carrier gas, e.g., air or nitrogen, and protective gas, e.g., hydrocarbon or inert gas. The shredder light fraction and the carrier gas may be injected into the molten metal bath as a main jet and oxygen may also be injected into the molten metal bath as a secondary jet. The primary jet and the secondary jet may be surrounded by a gas jet formed by the protective gas being injected into the molten metal bath.

Abstract: A charge of scrap is melted in a furnace (1) with post-combustion of the fumes by injection of an oxygenated gas into the space in the furnace above the charge. During periods of post-combustion, the oxygenated gas is injected in the form of several jets each having a flow rate comprised between about 400 and 1200 Nm.sup.3 /h and an injector (11, 12) outlet speed comprised between about 50 and 150 m/s, preferably between about 500 and 900 Nm.sup.3 /h and between about 70 and 125 m/s. Several groups of injectors (11, 12) are used, having an outlet tangential component relative to the vertical axis (X--X) of the furnace (1), successive groups of injectors being disposed at different levels (N.sub.1, N.sub.2) and oriented in alternate circumferential directions.

Abstract: A method for introducing gas into a liquid wherein a gas stream is ejected from a lance spaced above the liquid surface and directed from the lance onto the liquid surface. The gas retains substantially all its original jet axis velocity when it contacts the liquid surface, and substantially all of the gas penetrates the liquid surface and is introduced into the liquid. Preferably the gas stream is surrounded by a flame envelope running from the lance to the liquid surface, which shields the gas from ambient gas entrainment. The gas stream preferably forms a gas cavity within the liquid having a diameter substantially the same as the diameter of the gas stream as it is ejected from the lance.

Abstract: A method for carrying out post combustion in an electric arc furnace comprising forming a preferential gas stream within the electric arc furnace, concentrating carbon monoxide within the gas stream, and providing post combustion oxygen into the gas stream where the carbon monoxide is concentrated.

Abstract: Electric arc furnace with alternative sources of energy, which functions with direct current or alternating current and comprises at least one lance (12) to inject pure or combined oxygen above the bath (16) and a plurality of tuyeres (13) positioned in the hearth of the furnace (10) to inject oxygen below the bath, the tuyeres (13) being cooled by a peripheral movement of a cooling mixture consisting of at least one gas having a high cooling power (methane, butane, inert gases, etc.) and of at least one diluting gas (nitrogen, carbon dioxide), pipes (15) being included to introduce additives and powdered coal, post-combustion burners (28) possibly being comprised, the tuyeres (13) including an oxygen delivery pipe (18) having a diameter greater than 8 mm., the oxygen pressure being capable of being modulated according to the working steps, there being a constant minimum pressure of delivery.

Abstract: A tuyere for refining molten metals or melting metal scrap or oxides charged into a vessel. The tuyere comprises three concentric pipes of copper or stainless steel encased in refractory. An annular stream of natural gas surrounds an annular stream of oxygen which in turn surrounds a core stream of natural gas. All three streams are expanded as they flow through the tuyere and as a result an accretion forms at the tip of the tuyere. The accretion protects the tuyere and the gas streams are controlled so that the accretion is maintained at a desired size which neither blocks the tuyere, nor permits burnback of the pipes.

Abstract: A method of steelmaking in an at least partially refractory lined furnace. The process includes the steps of retaining a portion of a hot liquid slag from a previous heat, and altering the retained slag with basic slag forming material to increase its basicity, melting temperature, and viscosity, and to reduce its melting temperature below the melting point. The altering step is performed before charging ferrous materials for a new heat. Altered slag is then positioned on the bottom of the furnace, or on the furnace walls, or both, using a slag coating technique. Ferrous metal is then charged, after which a second charge of basic slag forming materials may be added prior to and/or during the first controllable oxygen blow. A slagging off step is conducted after less than one-half of the oxygen is introduced into the heat and when the mass of oxygen already introduced is sufficient to oxidize approximately all of the silicon introduced with hot liquid metal charged into the furnace.