Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-05-19
1999-08-03
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75512, 75529, 75531, 75532, 75533, 75537, 75538, 75540, 75543, 75544, C21C 532, C21C 710
Patent
active
059319852
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a process for blowing oxygen-containing gas, with and without solid material, on a metal melt in a metallurgical vessel, a process for generating a burner flame and corresponding devices.
2. Description of Related Art
Processes and devices by which oxygen is blown on a metal melt and by which the melt can be heated by admixing fuel are known. For example, European Patent publication 0 584 814 A2 discloses a top-blow lance with a Laval-type mouth construction and bore holes though which a combustible medium is injected into the main flow of the lance. The main flow, comprising oxygen or oxygen-containing gas, exits the lance nozzle at supersonic velocity, but under conventional flow conditions. The lance disclosed in this reference has a water-cooled jacket but does not provide a device for injecting solids.
Installations in which solids may be added ordinarily have addition devices. For example, German Patent publication 20 26 780 C2 discloses an addition hopper which is inserted in the cover of the vessel and through which solid material--in this case, scale as oxidizing agent--may be added to the melt.
German Patent publication 29 18 213 C2 discloses a process and a device for metallurgical treatment of metal melts in which a multiple-phase treatment is made possible in a single device in which, while retaining the closing hood, at least a first device--an electrode, in the present case--which is guided through the cover is replaced by a second device, in this case a fresh lance.
It is the object of the present invention therefore to provide a process and a lance suitable for such process as a unitary structural component part in which, in a simple design and without structural conversion, various different process steps in the treatment of metal melts in a metallurgical vessel may be performed while increasing the insertion rates of the individual media.
SUMMARY OF THE INVENTION
The present invention is directed to a lance for treating liquid metal melts in metallurgical vessels, especially steel under vacuum in RH vessels, the lance having at its top at the inner feed pipe of the lance a Laval-type opening for guiding oxygen and a cooling jacket along its entire length. The lance is connected at the bottom end to an oxygen and coolant supply station. A deflector ring is fastened in the oxygen feed pipe at a distance I.sub.B in the direction of the flow of gas in front of the narrowing critical diameter of between 0.7 and 0.9 D.sub.S, where D.sub.S is the clearance width of the oxygen feed pipe. A solids feed pipe is provided in the oxygen feed pipe so as to be held at the bottom end and guided coaxially thereto, this solids feed pipe ends at the top in front of the deflector ring in the direction of the flow of gas at a distance I.sub.P of between 0.1 to 0.3 D.sub.S. The deflector ring preferably has a construction downstream which is comparable with a Laval-type lance mouth. In addition, the narrowing may include adjusting elements by which the critical diameter D.sub.K may be adjusted such as tilting levers which are supported at one end.
The lance may be constructed to include nozzles arranged in the Laval-type lance mouth, which are connected to supply lines. The lance having a cooling jacket along its entire length and communicating at the bottom end with a supply station supplying oxygen, coolant and fuel gas. A deflector ring is fastened in the oxygen feed pipe at a distance I.sub.B of between 0.7 to 0.9 D.sub.S, where D.sub.S is the clearance width of the oxygen feed pipe. Provided in the oxygen feed pipe is a pipe which is held at the bottom end, guided coaxially thereto and ending at the top in front of the deflector ring in the direction of the flow of gas at a distance I.sub.P of between 0.1 to 0.3 D.sub.S. At least six nozzles are arranged as groups of at least three, each in a horizontal plane. The first nozzle is at a distance I.sub.D from the narrowing which is greater than 1.4 D.sub.K, where
REFERENCES:
patent: 5060867 (1991-10-01), Luxton et al.
patent: 5571307 (1996-11-01), Sizov et al.
patent: 5714113 (1998-02-01), Gitman et al.
Meyer Ulrich
Schoeler Horst-Dieter
Sizov Anatoly
Andrews Melvyn
Mannesmann Aktiengesellschaft
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