Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-05-22
2000-03-21
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75571, 266213, 266248, 266900, C21C 108, F27B 720
Patent
active
060397861
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to processes for melting metal charges in a rotary furnace equipped with at least one oxygen burner.
(ii) Description of Related Art
In known processes the oxygen burner, controlled in stoichiometric conditions, ensures the melting of the metal charge containing, optionally and for purely metallurgical reasons, small quantities of solid fuels, generally not exceeding 1% of the metal charge, in order to limit the formation of undesirable unburnt volatile compounds which, also where the oxygen burner is sued, limit the conditions in which the combustion is performed and, consequently, the rate of melting of the charge in the furnace.
A process for melting solid materials using an air or oxycombustible burner well under stoichiometric is known in DE-A-4142301, in which process oxygen is added in the oven with the aid of nozzles.
SUMMARY AND OBJECTS OF THE INVENTION
The objective of the present invention is to create an improved process enabling the rate and efficiency of melting in a given furnace to be significantly increased, while reducing the overall energy consumption.
To do this, according to one characteristic of the invention, the process includes the stages of adding a charge of solid fuel included between 1.5 and 9% to the metal charge to be melted and of injecting at least one jet of oxygen in the direction of the combine charge in the furnace.
According to other characteristics of the invention: and 9%, advantageously between 2 and 6%; supersonic; between the flame of the burner and the combined charge in the furnace. supersonic; action, between the flame of the burner and the combined charge in the furnace.
Another objective of the present invention is a rotary furnace for implementing such a process, including, besides an oxygen burner, at least one oxygen lance placed so as to direct at least one jet of oxygen towards the bottom of the furnace.
With the process according to the invention the combustion is extended into the charge itself, where the oxygen injected by the lance interacts with the solid fuel which burns in direct contact with the metal, thus extremely considerably increasing the reaction surface and thus promoting accelerated melting without affecting the temperature conditions at the furnace refractory and therefore not reducing the lifetime of the latter. Furthermore, since an appreciable proportion, exceeding 35%, of the total combustion energy is provided in the charge by the solid fuel, the power of the burner and hence its cost can be significantly reduced.
Other characteristics and advantages of the present invention will emerge from the following description of embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic view, in lengthwise section, of an embodiment of a furnace for melting metal according to the invention;
FIGS. 2 and 3 are, respectively, side and sectional views of an embodiment of a multitube oxygen lance;
FIG. 4 is a partial view in lengthwise section of a burner with integrated lance according to the invention;
FIG. 5 is an end view of the burner of FIG. 4;
FIG. 6 is a view in lengthwise section of another embodiment of a burner with integrated lance according to the invention;
FIG. 7 is an end view of the burner of FIG. 6;
FIGS. 8 to 11 are graphs illustrating the operating parameters according to the conditions of Tables 1 to 3;
FIG. 12 is a graph illustrating the relationships between the rate of melting and the percentage of energy of combustion in the combined charge of the furnace.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 a rotary furnace 1 is shown, in the end door 4 of which are fitted an oxygen burner 5 pointing towards the charge and an oxygen lance 2 which can be positioned adjustably by virtue of a guiding device 3. According to the invention the lance 2 is pointed so as to direct, in the furnace 1, a high-speed, typically supersonic jet of oxygen towards a combined charge of metal, typically of steel, to be melted a
REFERENCES:
patent: 3436066 (1969-04-01), Bouchet
patent: 4414026 (1983-11-01), Fukushima et al.
patent: 5123364 (1992-06-01), Gitman et al.
patent: 5163997 (1992-11-01), Sherwood
patent: 5714113 (1998-02-01), Gitman et al.
Andrews Melvyn
L'Air Liquide Societe Anonyme pour l'Etude et, l'Exploitation de
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