Metallurgical apparatus – Process
Reexamination Certificate
2001-05-01
2003-05-06
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
C266S225000, C266S270000
Reexamination Certificate
active
06558614
ABSTRACT:
The invention relates to a method for producing a metal melt in a metallurgical vessel, in particular an iron or steel melt, feed substances, which contain metals and/or metal oxides, being charged in solid and, if appropriate, molten form into the metallurgical vessel, the main part of the energy necessary for the melting and, if appropriate, finish-reduction of the feed substances being applied electrically and/or by the combustion and/or gasification of carbon-containing materials. The invention relates, further, to a multi-functional lance for use in a method according to the invention.
EP 0 257 450 A2 teaches a method for increased energy introduction and current saving in arc furnaces for steelmaking. In this case, free oxygen jets emanating from blow-on devices are used for the post-combustion of the furnace waste gases and under-bath nozzles are used for moving the bath. Coal for the formation of CO is blown in via a hollow electrode or under-bath nozzles and the oxygen for the formation of CO is likewise supplied to the melt through under-bath nozzles.
A disadvantage, here, is the high outlay in terms of apparatus for blowing in the coal, the formation of CO and post-combustion. Furthermore, the under-bath nozzles required, which are loaded with oxygen, are exposed to high wear and, correspondingly, have only a short service life.
There have also been many attempts to make devices and methods available for heating and blowing for metallurgical purposes and for combustion in metallurgical reactors.
Thus GB 1,015,581 discloses a burner with a central oxygen duct, with a fuel supply duct surrounding the latter and with an outer annular duct for oxygen. The fuel and oxygen are intermixed immediately after emerging from the respective mouths. According to GB 1,015,581, the burner is provided for use in all top-blowing oxygen steelmaking methods.
However, such a burner is unsuitable for sucking in furnace gases to an appreciable extent for post-combustion, so that it can contribute nothing or only little to improving the energy balance.
AT 402,963 B describes the combustion of fuel by means of a specially designed burner. As a result of the rapid intensive swirling of the fuel together with oxygen in a chamber of the burner, the outflowing mixture very soon becomes relatively slow over the running distance of the mixture jet. Such a burner therefore has relatively short flame length and in this case, once again, neglects to suck in furnace gases, so that this, too, can contribute little to improving the energy balance. Furthermore, such a burner is suitable only to a limited extent for the refining of a steel melt.
WO 91/00366 describes a method and a device for heating a metallurgical furnace, an inner oxygen duct being encased annularly by a fuel duct. In this case, the fuel is supplied by means of an inert to weakly reducing carrier gas. Here too, no possibility is given for the post-combustion of furnace waste gases by sucking them into the burner jet or for the refining of the melt.
The object of the present invention is, therefore, to provide a method and a device for use in such a method which avoid the disadvantages known from the prior art. In particular, a method is to be provided, which requires less energy, both electric and fossil, than known methods in order to produce a metal melt and which can be carried out in a shorter time, and multi-functional lances are to be provided, by means of which the method according to the invention can be carried out and which, furthermore, are kept compact and simple in terms of construction and, when a repair is necessary, can be repaired again easily and simply.
This object is achieved, according to the invention, by means of the combination of the following features:
that
A) in a combustion step, additional energy is supplied to the feed substances by the blowing-in, taking place by means of one or more multi-functional lances, and combustion of gaseous and/or liquid carbon-containing materials and oxygen-containing gas,
B) in a cutting and melting step, the solid feed substances are cut and partially melted by the intensified blowing-in, taking place by means of the multi-functional lance or lances, of oxygen-containing gas,
C) in a refining step, the melted feed substances are refined by the intensified blowing-in, taking place by means of the multi-functional lance or lances, of oxygen-containing gas,
D) in a carbon blow-in step, alloying carbon and/or additional energy is supplied to the feed substances by the blowing-in, taking place by means of the multi-functional lance or lances, and, if appropriate, combustion of fine-grained and/or dust-like solid carbon-containing materials,
E) in a post-combustion step, the waste gases from the metallurgical vessel are afterburnt by the blowing-in, taking place by means of the multi-functional lance or lances and directed away from the respective multi-functional lance in at least two of the three spatial directions, of oxygen-containing gas into the waste-gas space of the metallurgical vessel,
F) in a solid blow-in step, the necessary substances are supplied to the feed substances by the blowing-in, taking place by means of the multi-functional lance or lances, of fine-grained and/or dust-like solid aggregates and/or alloying agents, in order to achieve the desired composition of the metal melt,
steps A) to F) being carried out, depending on the composition of the feed substances and on the desired composition of the metal melt, selectively in any desired combination, in particular in succession and/or in reverse order and/or simultaneously and/or omitting individual steps of steps A) to F).
By means of the method according to the invention, metal melts can, according to an advantageous feature, be produced, for example, in electric furnaces or converters or melt-down gasifiers or in a particularly energy-saving and time-saving way. Furthermore, ladles or vessels for the conversion of slag may be used as metallurgical vessels. The respective metallurgical vessel may be under overpressure, atmospheric pressure, underpressure or a vacuum.
The multi-functional lances used for the method according to the invention make it possible to carry out the individual method steps flexibly, with free choice and, in particular, also simultaneously.
There is an increase in the use of solid metal carriers for producing melts, in particular steel melts, since these materials are already metallic and therefore no longer have to be reduced at a high outlay. Such solid metal carriers are therefore recirculated to an increasing extent. In particular, such materials, such as scrap, pig iron, cast iron, etc., are processed in electric furnaces, so that it is particularly important to improve the operation of electric furnaces. Rapid melting-down and refining in order to set short furnace cycle times are important for achieving low heat losses and electrode consumptions and for the uninterrupted feeding of modern continuous casting plants. Moreover, the melting capacity of electric furnaces is also to be increased as a result of the controlled parallel introduction of electric and fossil energy.
These requirements are satisfied by the method according to the invention.
According to an advantageous feature of the method according to the invention, one or more multi-functional lances are used jointly with burners and/or refining lances and/or post-combustion lances and/or, in the case of electric furnaces, under-bath nozzles and/or hollow electrodes and/or, in the case of converters, side nozzles, which in each case are known per se.
It is thereby possible that burners and/or refining lances and/or post-combustion lances cover, as it were, the basic loads of a corresponding method step and, in addition, energy is introduced, melting carried out, refining carried out, coal and/or alloying agent blown in, waste gas afterburnt, etc., at particularly important points by means of the multi-functional lance or lances additionally used, for the purpose of achieving a rapid method flow.
In a further advantageou
Kastler Scott
Ostrolenk Faber Gerb & Soffen, LLP
Voest-Alpine Industriean-lagenbau GmbH
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