Abstract: The present invention relates to a device for degassing molten steel, comprising an evacuation vessel (2), a pouring ladle (3), an inlet nozzle (4) with a gas purging device (5) arranged therein, and a discharge nozzle (1), wherein at its lower edge (9), in a radial direction in relation to the central longitudinal axis (6) of the discharge nozzle (1), the discharge nozzle (1) has at least one bore (7).

Abstract: A method for refining molten steel by immersing the lower opening end of a cylindrical immersion tube equipped with a lance into the molten steel contained in a ladle, controlling the pressure in the cylindrical immersion tube to a prescribed pressure range to suck up the molten steel, injecting an agitation gas from the bottom of the ladle towards the surface of the sucked-up molten steel, and decarburizing and refining the molten steel under a reduced pressure, characterized in that the method comprising the steps of; controlling the pressure Pt (Torr) in the cylindrical immersion tube so as to satisfy the following formulae (1) and (2), blowing oxygen gas to the surface of the molten steel through the lance, and decarburizing and refining the molten steel under a reduced pressure; Pt>760−1.297×107/Dc2  (1) K=1.71×Dl0.211×Dc0.438×Wm−1.124×Qg0.519×Pt−0.410>0.

Abstract: A method for vacuum decarburization refining of a molten steel includes providing a vacuum tank having a one-legged, straight barrel snorkel as a lower portion of the vacuum tank. The a degree of vacuum in the vacuum tank is regulated at a high carbon concentration region to a value in a range of −35 to −20 in terms of G defined by the following equation (1): G=5.96×10−3×T×ln(P/Pco)  (1), wherein Pco=760{10(−13800/T+8.75)}×(% C)/(% Cr)  (2), and wherein P<760, T represents molten steel temperature, K, and P represents the degree of vacuum in the vacuum tank, Torr.

Abstract: A molten steel refining apparatus and a method therefor, in which the carbon component of molten steel can be easily removed, the temperature drop of molten steel can be effectively reduced, and a stable operation is realized. The apparatus for refining molten steel for manufacturing ultra low carbon steel includes an RH vacuum-degassing device consisting of a vessel and a snorkel composed of an up-leg and a down-leg. The apparatus further includes a plurality of gas injection lance nozzles each consisting of an inner tube and an outer tube, and installed on the side wall of the vessel of the RH vacuum-degassing device so as to inject gas toward molten steel within the vessel. The inner tube includes a throat for forming a jet stream of super-sonic velocity, and the outer tube injects cooling gas for cooling the inner tube.

Abstract: In a process for vacuum refining a molten steel wherein a refining flux is used, a fuel gas and an oxygen gas are spouted into the outlet of a top-blown lance of a vacuum refining apparatus to form a burner flame below the top-blown lance, and, at the same time, a refining flux is fed into the top-blown lance with the aid of an oxygen gas as a carrier gas and further passed through the burner flame, and the heated and melted refining flux is allowed to arrive at the surface of the molten steel. In this case, the refining flux feed rate and the circulating flow rate of the molten steel during vacuum refining are regulated so as to have a predetermined relationship, achieving a low flux consumption throughout a period of single refractory life of the vacuum tank.

Abstract: A process for adjusting the composition of a liquid metal, such as steel, is provided wherein liquid metal is sucked up from a start receptacle into a reactor which is at a reduced pressure with respect to the start receptacle. First, the liquid metal is made to flow inside the reactor under conditions close to plug flow where it undergoes a metallurgical treatment. Next, after the liquid metal has been conveyed through the reactor it is completely discharged into a finish receptacle which is also at a reduced pressure with respect to the reactor. To insure thorough mixing, the reactor is divided into a plurality of cells, each of which has its own independent gas injector for agitating the liquid metal therein.

Abstract: In a vacuum degassing and decarburization treatment, the present invention uses a CO.sub.2 gas as a recirculating gas and as a stirring gas without inviting stoppage of decarburization and an increase in the carbon concentration and moreover, without an increase in the amount of addition of an alloy, and can reduce the gas cost. The present invention provides a production method for a low carbon molten steel which comprises blowing a CO.sub.2 gas from the start of degassing treatment till the carbon concentration of the molten steel reaches 50 ppm in vacuum degassing and decarburization treatment of the molten steel, and thereafter blowing an Ar gas.

Abstract: An apparatus for vacuum treating molten steel includes a ladle having a sidewall, a substantially circular closed bottom, and an open top. A first gas injector is operably associated with the bottom for introducing a supply of a selected first gas into the ladle. A barrel degasser is operably associated with the ladle for being introduced into the ladle through the open top. The degasser includes a generally cylindrical shell having a single substantially continuous diameter opening them through defining a treatment space. A second gas injector is radially directed and operably associated with the shell for communicating with the treatment space. A source of the first gas is in flow communication with the first and second injectors. A vacuum source is operably associated with the barrel degasser for applying a vacuum to the treatment space.

Abstract: The invention relates to a process and a device for blowing oxygen over a metal melt under a vacuum. The oxygen is to be applied over a large surface with a large intermediate phase area while avoiding overcooling in the metal bath by simple, easily maintained structural means. The flow of oxygen in the lance is accelerated and compressed into plug-shaped oxygen pulses, which leave the lance in succession and which form an oxygen bell over the vacuum above the metal melt, having an oxygen casing and an oxygen core, the core moving at a speed similar to that of the casing. At the base of the wall 41 of the blowing lance 40 there is an annular nozzle 42. At a distance behind the annular nozzle 42 in the direction of flow of the oxygen there is a blind tube 44 forming a fan-shaped compartment 43. Between the bottom 46 of the blind tube 44 and the head of the blowing lance 40 there is a pre-nozzle chamber 48 and in the head of the blowing lance 40 there is at least one base nozzle 50 directed toward the melt.

Abstract: A method, for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool, employing an at least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit and thereby inducing a flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. According to the present invention, the inert gas is fed into the conveying conduit at a supersonic velocity, thereby simultaneously effecting a degassing of the molten metal while it is being conveyed.

Abstract: A method of refining a molten metal or a molten alloy through degassing, wherein a gas is blown into a molten metal or a molten alloy contained within a refining container, while stirring by utilizing an electromagnetic force, to superimpose the blown gas onto a molten metal or a molten alloy, and the stirring by an electromagnetic force, to thereby refine the blown gas, and at the same time, increase the residence time of the blown gas in the molten metal or molten alloy bath and homogeneously disperse the blown gas in the molten metal or molten alloy bath.

Abstract: A method, for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool, employing an at least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit and thereby inducing a flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. According to the present invention, the inert gas is fed into the conveying conduit at a supersonic velocity, thereby simultaneously effecting a degassing of the molten metal while it is being conveyed.

Abstract: A method, for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool, employing an at least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit and thereby inducing a flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. According to the present invention, the molten metal is alloyed simultaneously with its conveyance, the same inert gas being employed for both conveying the molten metal and for entrainment of the alloying metal.

Abstract: A method, for the conveyance of molten metal from one place to another, in a high-temperature molten metal pool in a metal-melting furnace or out of said molten metal pool, employing an at least partially-inclined elongated conveying conduit and gas feed means for feeding inert gas into the lower end of the conveying conduit and thereby inducing a flow of molten metal in and through said conveying conduit, is disclosed, along with suitable apparatus for carrying out the said method wherein the parts or elements coming into contact with the high-temperature molten metal pool are of a suitable refractory material. According to the present invention, an intermittent or pulsating inert gas feed is employed to produce essentially spherical or cylindrical bubbles within the conveying conduit, thereby resulting in greater efficiency and economy because of the possibility of reducing the quantity of inert gas employed to induce the flow of an identical amount of molten metal.

Abstract: Method for decarburisation of steel in a vacuum treatment chamber consisting of an upper part (4) in the shape of a bell, of an intermediate ring (5) and of a lower part (6) in which the bath of metal to be treated (2) is located and which is equipped with two legs (7, 8) which are immersed in the steel ladle (9) containing all the metal (10) to be treated, characterised in that oxygen is blown horizontally over the bath of metal to be treated (2), at the level of the intermediate ring (5), substantially at the centre of the latter.Vacuum steel-treatment chamber in which at least two horizontal tuyeres (11, 12) are provided in the intermediate ring (5) of the said chamber, substantially in the centre of the latter.

Abstract: A method of producing an ultra-low-carbon steel by using a vacuum degasser on a molten steel has the steps of conducting vacuum decarburization to attain a predetermined level of carbon content, e.g., 25 ppm or below, in the molten steel while progressively reducing the pressure in said vacuum degasser, conducting addition of hydrogen in which hydrogen is dissolved in said molten steel while said pressure is temporarily elevated to 20 Torr or above, and conducting final decarburization after reducing said pressure to 2 Torr or below. The addition of hydrogen may be conducted to meet the following conditions:[H].gtoreq.{([C]-[C]final)/5}+4wherein [H] represents the hydrogen content (ppm) in said molten steel in the state after the addition of hydrogen, [C] represents the carbon content (ppm) in the molten steel in the state after the addition of hydrogen, and [C] final represents the final carbon content (ppm) to be obtained.

Abstract: A method and apparatus for vacuum degassing blows gas into molten metal so as to form a substantially uniformly distributed bubble over the path area defined by an induction pipe. In order to achieve this, discharge nozzles are separated into at least two groups. The pressures of the gases discharged through the discharge nozzles in different groups are controlled independently of the other so that gas blown through a first group of nozzles forms bubbles at around the central portion of the induction pipe and the pressure of the gas blown through the other group of nozzles is adjusted for forming the bubbles in the vicinity of the periphery of the induction pipe.

Abstract: A process of degassing and decarbonizing is directed to a process for performing vacuum degassing non-deoxidized or slightly deoxidized molten steel utilizing RH process or DH process. The process includes blowing of oxygen or oxygen containing gas toward the surface of the molten steel in a vacuum chamber for promoting decarbonizing reaction. The process further includes a step of combustioning of CO gas in the vicinity of the surface of the molten metal at a timing, in which concentration of (CO+CO.sub.2) in an exhaust gas is higher than or equal to 5% and a ratio of CO.sub.2 versus (CO+CO.sub.2) in the exhaust gas is approximately 30%. Heat generated by combustioning of CO gas is utilized for compensating temperature drop of the molten steel.

Abstract: Gas injection into a metal melt, accompanied if desired by powdered or solid treatment substances, is by way of a nozzle inserted into the wall of a melt-containing vessel. The nozzle bore initially has a stopper at its inner end and a delivery pipe smaller than the bore is movable therein. Before injection, the pipe and bore adjacent the stopper are cooled by gas. By thrusting the pipe against the stopper while sufficient gas flow and pressure is maintained, the stopper is dislodged and the gas will enter the melt as a jet which leaves the pipe at a injection cooling, then when injection is completed allowing the melt to enter and rapidly freeze locking the pipe safely in the bore.

Abstract: A killed steel is stirred in a ladle with the aid of gaseous carbon dioxide. Before the beginning of the stirring in the ladle, there is added to the quantity of deoxidizer usually employed, a supplementary quantity of deoxidizer in the molten metal, the rate of supply of carbon dioxide, bearing in mind the capacity of the ladle and the duration of the stirring, remaining less than or equal to the maximum rate of supply corresponding to the oxidation of the supplementary quantity of deoxidizer at the end of the stirring.

Abstract: A high-strength steel for valve springs, consisting of 0.50-0.70 wt. % of carbon, 1.50-2.50 wt. % of silicon, 0.50-1.20 wt. % of manganese, 1.50-2.50 wt. % of nickel, 0.50-1.00 wt. % of chromium, 0.20-0.50 wt. % of molybdenum, 0.15-0.25 wt. % of vanadium, and the balance being iron and inevitably included inclusions. Also disclosed is a process for producing such a high-strength steel, which includes a step of minimizing oxygen in a melt of the steel, so as to reduce the oxygen content of the steel to 15 ppm or less, and a step of adding calcium to the melt and thereby controlling the form of the inclusions. The process may further includes a step of minimizing titanium and nitrogen in the melt, so as to reduce the titanium and nitrogen content of the steel to 50 ppm or less, and 60 ppm or less, respectively.

Abstract: The process includes two major phases, each including a converter blowing step and a discharge step, whereby the first discharge step is also a preparatory step for the second blowing step. The steel is dephosphorized, desulfurized, and decarbonized under formation of basic slag which is retained in the converter during the first discharge. Lime, limeflux and possibly clay is added prior to the second blowing together with, preferably, silicon for deoxidation. After the second discharge, additional alloy components may be added.

Abstract: The dissolved oxygen content in a bath of molten steel is controlled, in one embodiment, by diluting a slag layer atop the bath with an oxide such as lime (CaO), to reduce the percentage of MnO and FeO in the slag, and stirring the bath of molten steel. In another embodiment, a gaseous mixture of an inert gas and carbon monoxide is disequilibrium with the carbon and dissolved oxygen content is bubbled through the bath.

Abstract: There is practiced a method of making low carbon silicon steel in which the lining of the ladle is made of dolomite instead of fireclay or alumina, and there is added to the ladle, before the metal is teemed into it, a pre-melted or pre-fused mixture containing appropriate portions of calcium silicate, lime, magnesia, and spar, and argon bubbling is practice as before but preferably for a slightly longer period of time, and the ladle is provided during argon bubbling with a hood or lid. There is then obtained a product steel with desirably low contents of oxygen and nitrogen, and without penalty in the form of higher contents of aluminum and titanium in the finished steel.

Abstract: A method and apparatus for pneumatic feeding of additives along pipes from an additive silo to converters. The additive is allowed to flow into a dispatching device, a scale or a similar device in it stopping the entrance of the additive when the desired quantity of additive has arrived in the dispatching device. The dispatching device is pressurized thereafter by means of compressed air, by means of which the quantity of additive is fed via a pipe into the converters.

Abstract: A process for continuous treatment of hot metal topped from a blast furnace is disclosed. The process involves the steps of deslagging the metal, flowing the deslagged metal along a launders and blowing treatment agents in powdered form in a gas jet into the hot metal as it flows along the launder, the treatment agents being lime, fluorite, iron oxide or sodium carbonate.

Abstract: The specification discloses fully continuous production of steel strip from ore. Ore is continuously charged in particulate form to a reactor where it is adhered to hot metal in a continuous flash smelting process. The hot metal is continuously refined, is continuously clarified by bubbling an inert gas through it, is continuously alloyed, and is then continuously degassed. The degassed metal is then continuously cast and continuously rolled to steel strip.

Abstract: An improved two phase basic steel refining process for phosphoric pig iron is described which comprises forming a steel having a phosphorus content of not greater than 0.

Abstract: A hollow body, a rotor, with holes in the bottom and the side wall, is immersed down into a liquid and rotated with the help of a shaft suspended over the liquid.The liquid, which enters the rotor through the hole in the bottom, will, on account of the centripetal force, acquire a surface in the shape of a paraboloid of revolution. The centripetal force will throw the liquid out through the holes in the side wall, while new liquid will continuously enter through the bottom of the rotor.The shaft for the rotor can be hollow, and through this gas, solid or liquid materials can be added to the liquid.The invention makes possible the treatment in various ways of different types of liquid, from aqueous suspensions to molten metal.

Abstract: This invention uses a dual basicity (DB) flux during the refining of steel which comprises the use of one or more flux components with high basicity/activity, for example sodium carbonate and/or barium oxide, with one or more normal fluxes having a lower basicity/activity such as calcium or magnesium oxides or dolomite. It has been found that it is only necessary to use a small percentage of the said high basicity fluxes in the total flux, for example 10%. The use of the said DB type of flux is particularly apt when the total amount of flux used is reduced to give a slag with a low Vee Ratio (CaO:SiO.sub.2), of the order of 1.0 to 2.0, and when magnesia is present in the slag formed preferably derived from an added lower basicity (MgO) flux component or partly from the furnace refractory lining.