Abstract: A gas injection lance for use in metal refining is disclosed. The lance includes a tube having an inner diameter profile and a throttle member slidably received with the tube. The tube and throttle member define an annular gas flowpath. The throttle body may be moved axially within the tube to modify the characteristics of the flowpath.

Abstract: Nozzles for a refining lance are presented which are spaced upwardly from the head of the lance and supply post-combustion oxygen to the space above a molten metal bath undergoing refining. Each of the nozzles has a mouthpiece with two parallel sharp edges which are arranged in planes passing substantially through the axis of the lance and which are connected by slightly rounded edges. Above the mouthpiece of each nozzle is a converging part.

Abstract: For improving permeability of a metallurgical vessel bottom provided with permeable refractory elements for controlled injection of a stirring fluid into a molten metal bath, the metallurgical vessel is emptied of its contents, a castable composed of a refractory material compatible with the refractory material of the bottom is deposited in the bottom and spread over the latter, and the castable is left to dry and set, while maintaining in the permeable refractory elements a sufficient pressure to provide a permanent flow of a stirring fluid. A hydraulic magnesian refractory castable used in this method has a content of water of substantially between 8 and 10% by weight.

Abstract: An apparatus and method is presented for emptying metallurgical vessels, and in particular steelmaking converters containing metal and slag, whereby the slag is effectively separated from the metal during pouring. The apparatus includes at least on permeable refractory element located near the flow hole. An agitating gas is fed through the refractory element thereby creating a bubbling froth which effectively obstructs most of the slag from being carried along by the vortex which forms above the vertical flow hole.

Abstract: The service life of permeable refractory elements is improved by conserving in a vessel a fluid slag formed during refining of a charge after a liquid metal has been cast by tipping the vessel, depositing and spreading the slag over the bottom by bringing the vessel back to its upright position, and leaving the slag to harden and set on the bottom, while a sufficient pressure is maintained in the permeable refractory elements to ensure a permanent flow of a stirring fluid.

Abstract: A nozzle for the refining of metals by oxygen blasting from above the melt is presented. The nozzle includes a nozzle head having a blast pipe therethrough upstream of the mouth of the nozzle. The blast pipe directs a jet of gas comprised, at least in part, of oxygen, having a supersonic speed onto the melt. The blast pipe includes an inner tube. The lower portion of the inner tube has a throat positioned between a convergent and divergent sections, this lower portion defining a laval nozzle. The blast pipe also includes an outer tube coaxial with the inner tube and having a greater cross section than the inner tube. The mouth of the inner tube is spaced back (downstream) from the mouth of the blast pipe. The inner and outer tubes are each provided with flow control valves, and are connected to sources of pressurized gas. Devices are provided to vary the cross sectional area of the mouth of the inner tube.

Abstract: A nozzle for refining metals or ferroalloys by oxygen blasting from above the melt is presented. The nozzle terminates at a nozzle head and includes at least one central blast pipe for directing a jet of oxygen having supersonic speed. A chamber is interposed between the mouth of the blast pipe and the mouth of the nozzle head. This chamber widens progressively from the mouth of the blast pipe, and narrows toward the mouth of the nozzle head. At least one opening from at least one lateral duct opens to the chamber in the vicinity of the blast pipe mouth. Each lateral duct is connected to a source of gas, and includes an inidividual flow control valve. Preferably, at least three lateral ducts are arranged symmetrically around the blast pipe mouth.

Abstract: For improving permeability of a metallurgical vessel bottom provided with permeable refractory elements for controlled injection of a stirring fluid into a molten metal bath, the metallurgical vessel is emptied of its contents, a castable composed of a refractory material compatible with the refractory material of the bottom is deposited in the bottom and spread over the latter, and the castable is left to dry and set, while maintaining in the permeable refractory elements a sufficient pressure to provide a permanent flow of a stirring fluid. A hydraulic magnesian refractory castable used in this method has a content of water of substantially between 8 and 10% by weight.

Abstract: The service life of permeable refractory elements is improved by conserving in a vessel a fluid slag formed during refining of a charge after a liquid metal has been cast by tipping the vessel, depositing and spreading the slag over the bottom by bringing the vessel back to its upright position, and leaving the slag to harden and set on the bottom, while a sufficient pressure is maintained in the permeable refractory elements to ensure a permanent flow of a stirring fluid.

Abstract: Apparatus for closing the discharge aperture of a metallurgical vessel is presented. This apparatus includes a closure element attached to a pivoted lever in order to prevent undesirable discharge of slag at the beginning and end of the casting process and during refining. The lever pivotally opens and closes the aperture by means of a piston rod and pressure cylinder. The closure element, preferably made from wood, is temporarily attached to the lever by a friction fit and is designed to be used only once.

Abstract: Pig iron is refined by top blowing with oxygen and injecting inert gas from the bottom. The slag formation is minimized by controlled addition of lime to match the formation of slag components as they are generated by the process. This increases the capacity of the melt to receive a cold charge, e.g. of scrap.

Abstract: A method of and an apparatus for the refining of a molten metal overlain by a slag and in which cold solids are introduced, e.g. in the form of metal scrap. According to the invention the heat necessary to melt the scrap and prevent undue cooling of the bath is generated by directing a jet of neutral gas entraining carbon against the surface of the melt perpendicularly thereto at Mach 1.5 to Mach 2.5, while refining oxygen is directed at the surface from jets inclined to the carbon entraining jet and the melt is bottomblown by neutral gas to prevent excessive foaming of the slag.

Abstract: Process of refining of a metal bath in a crucible with oxygen blast at the top and crucible used.The invention consists essentially of providing in the bottom (15) of the crucible agitating gas injectors (15) located at least in a peripheral circular ring situated in immediate proximity to the refractory side wall. The injectors are preferably concentrated opposite the journals. Secondary injectors are, also preferably, provided in the bottom zone, intermediate between the ring and the center of the crucible.The invention makes it possible, in relation to the prior injection practice, to reduce the rate of dissolution of the agitating gas in the molten metal and then makes it possible to use a low-cost agitating gas, such as nitrogen, without risk of excessive nitridation of the bath.

Abstract: A process for refining a metal bath in a converter by oxygen blowing, particularly a molten metal liquid bath containing cold, solid substances, notably of scrap. Oxygen is distributed over the surface of the bath, so that there will be an after-combustion of CO released in the course of decarbonization. The thickness and consistency of a slag layer formed over the bath is actively regulated by injecting a rising inert gas through the bottom of the bath. The flow of rising gas may be regulated depending upon the oxygen content in the fumes of the converter, or upon the intensity of emission through the top of an oxygen blowing lance.

Abstract: A ferrous melt, e.g. of steel, is refined beneath a slag layer by blowing from above with an oxygen-containing gas through a lance and by bubbling an inert gas through the melt from the bottom. According to the invention, the consistency of the slag layer and/or its level is continuously detected on the one hand and the rate of decarburation of the bath is detected on the other hand and in response to these measurements the volume rate of flow of the bubbling gas is controlled on the one hand to maintain a predetermined spacing of the slag layer from the head of the lance and, on the other hand, a fluid consistency of the slag.

Abstract: A process for refining a steel melt in a furnace in which a steel melt is formed with a slag layer thereon, the thickness of which can be controlled by passing a stream of inert gas upwardly through the melt, while directing a first stream of oxygen into the melt from a lance positioned above the melt for the top-blowing refining thereof to produce carbon monoxide above the melt and feeding a second stream of oxygen from the lance for the post-combustion of the released carbon monoxide, while monitoring continuously the thickness of the slag layer, the height of the melt, the carbon monoxide post-combustion factor (%CO.sub.2 /%CO+%CO.sub.2) and the speed of decarburization of the melt and controlling the height of the lance above the melt and the discharge rates of total blown oxygen, the second stream of oxygen and the inert gas stream at any given time in accordance with a particular relationship.

Abstract: Slag is conditioned during blowing from above with oxygen of an iron melt by bubbling an inert gas into the melt from the bottom of the crucible in response to measurements made of the flowability of the slag layer and the speed of decarburization.