|Title of Invention||
A PROCESS AND A DEVICE FOR PRODUCING STEEL MELTS
|Abstract||Abstract The invention relates to a method and a steel works device for the metallurgical treatment of ferrous metals, in particular for producing steel melts. In order to carry out metallurgical work using ferrous metals, in particular to produce steel melts, in an energy-saving and inexpensive manner which does not harm the environment, the invention proposes carrying out all the metallurgical operations in one vessel, which firstly performs the function of a converter and, without the molten product being reladled, the function of an arc furnace. See Figure 2|
The invention relates to a method for the metallurgical treatment of ferrous metals, in particular for producing steel melts, and to an associated steel works device with at least one metallurgical vessel which can be closed by a swiveling cover which is connected via a flue gas elbow to a gas cleaning plant and through the centre of which at least one electrode can be passed, a device for filling the vessel with charge material, as well as a slag discharge hole and a melt tap hole disposed in the bottom of the vessel.
The market is making increasingly greater demands on the owners of electric steel works as regards quality, with respect to the level as well as the continuity and price level of the steel products. Because of the fluctuating prices of raw materials, an increasing number of producers plan also to use greater quantities of pig iron - liquid or in pigs - in addition to scrap in electric steel works.
The blowing of pig iron with high oxygen rates was previously reserved for the converter. For example,
DE OS 28 03 960 discloses a plant for refining pig iron by means of oxygen or oxygen-enriched gases in which a main hood is provided to catch the waste gases escaping during the refining which is connected to the main hood and leads to a dust removal plant. The discharge pipe comprises an opening through which the oxygen lance can usually be passed.
The main hood is connected to a cover which is disposed independently of the metallic vessel and with which it is formed as a device so that it can be moved to the side.
Electric arc furnaces are usually operated with direct current oil with alternating current. For example,
DE 43 02 285 Al discloses a double furnace device with twin-furnace vessels and a method for operating this device, which vessels can be closed by covers connected via flue gas elbows to a gas cleaning plant. As can be seen in Figure 2 of this publication, that firstly three electrodes are showed through the cover of a furnace operated with three-phase current and then one electrode is showed through the cover and, in the bottom of the vessel, the counter electrode of a furnace operated with direct current is represented. Both furnaces are operated such that one furnace is supplied with electrical energy to melt down the charge contained therein, while the other is completely separate from the electrical supply system and, following charging with the warm flue gases, the other furnace is filled. In metallurgical terms this is a single-stage process.
Metallurgical vessels have also already been proposed. For example, DE 34 19 030 CI discloses a metallurgical reaction vessel, in particular a steel works converter, which can be reached for each method section of a process and for operating devices which play a corresponding functional part and are disposed above and/or below the reaction vessel by being rotatably adjustable about a vertical axis of rotation. The operating devices include, e.g. the waste gas pipe", the charging device, the measuring lance, the blowing lance and the bottom lowering device. These are installed in a stationary manner, whereas the reaction vessel is turned into the appropriate position about the vertical axis of rotation.
The reaction vessel is suitable for respective methods. Thus it is used to produce metal melts, in particular steel melts, and to produce gases, e.g. CO gases from coal and a substance whose presence assists the reaction and which is in the process only consumed to a slight degree, if at all, such as, for example, pig iron—felts.-
The object of the invention is to provide a method for carrying out metallurgical work using ferrous metals, in particular for producing steel melts, in an epee^-saving and inexphisive manner while does not harm the environment and a device which is suitable furies.
Acc(H-dangly the present invention provides a process birr producing steel melts, the sad process comprising the steps of d|oxidizing an iron containing metal pool on a bottom of the vessel by adding Al/Si; charging low carbon iron charge materials into the metal pool in the vessel; supplying
oxygen to the vessel to provide non-electric heat enter| to the metal pod
and the charge materials; implementing refining of the charge materials
while simultaneously charging ing iron and adding lime into the metal pool;
materials while maintaining a portion of the pool in let vessel to permit
restarting of the process, the steps being carried out so |bat the vessel first
acts as a converter and ahead as a direct arc furnace.
I' The low carbon charge material has a carbon content of about 3.8 to
Accordingly the present invention also provides a device for producing steel melts by a process as herein above described, the said device comprising at least one metallurgical vessel having an upper part, a lower part, a bottom, and an open top; a cover swing ably arranged to close the top of the metallurgical vessel, the cover having a removable cover center with an opening; a flue gas elbow connected to the cover; a flush-off opening and a melt tap opening being arranged in the bottom of the vessel; a waste gas elbow having an opening configured to be peaceable on the cover center opening; at least one lance configured to be insert able into an interior of the upper part of the metallurgical vessel through the cover center opening via the waste gas elbow; and means for finishing heat energy to the vessel via an electric arc.
According to the invention all the metallurgical operations are carried out in
one vessel, which firstly performs the function of a converter and
function of an arc finance. This method can advantageously take place in
two metallurgical vessels which overlap in their work cycles by 50%.
After the metal melt has been tapped without slag from the arc finance, the bottom of the vessel contains an initial bath which was required in conventional arc melting to re-start the process. Al/Si is introduced to bind the liquid initial metal bath so as to prevent violent reactions with the liquid metal in the present method. The vessel is then charged with low-carbon metal in the form of scrap or liquid metal.
Oxygen is then surface-injected, so that the silicon content is reduced and the overall charge heated. Pig iron is simultaneously added as a cooling material during the reduction operation in order to maintain the temperature of the steel at a predetermined value. Calcium is added at the same time to adjust the passivity. No kind of electrical work is required during this entire period. Approximately 50% of the silicon-enriched slag is in the meantime drawn off. The waste gases are sucked off during the reduction operation. The phosphoric slag is drawn off upon completion of the surface injection operation.
The'operating devices are replaced at this point, the lances and the waste gas elbow being removed and replaced by the electrodes and the flue gas line being opened so that the melting work can then be carried out by the electric arc furnace. At the end of the process the residual slag is drawn off and the liquid melt tapped through the bottom tap.
Instead of the surface injection of oxygen through an oxygen lance, it is proposed that oxygen-natural gas or oxygen-oil burners be used to decarburize the pig iron and that these be operated with an exceptionally long flame and in a non-stoechiometric manner.
When liquid metal is used its temperature exceeds 1300°. Various metal mixes are proposed. A liquid pig iron to liquid metal ratio of approximately 50:50 has proved to be favourable in cost terms. A scrap: pig iron ratio of around 30:70 is also proposed. Yet another proposal lies in using scrap: pig iron: liquid metal in a ratio ranging from 10:60:30 to 10:40:50.
Following each complete method step the bottom tap is cleaned and closed again, the appropriate material is charged, the cover of the furnace vessel is closed, the lance or burner and the waste gas elbow are brought into position and the process can be restarted.
When using a double furnace installation a melting process by means of electrodes takes place in" the other furnace vessel during the blowing process. The flue gases are conveyed via a flue gas elbow into a mixing chamber, where they mix with the waste gases from the blowing process. As the blowing process permits very high waste gas temperatures through afterburning of the CO, any colder waste gases from the electric furnace operation are always after burned. This prevents the occurrence of any odour nuisance or possibly other hydrocarbons such as, for example, furans and dioxins.
In order to carry out the method, the invention proposes a steel works device with a metallurgical vessel employing covers whose
centre can be removed. The mouth of a waste gas elbow is applie
to the cover centre opening, and at least one lance or at least
one burner is brought into the interior of the upper part of the
metallurgical vessel- through this elbow and the opening in the
These adapted components enable the metallurgical vessel to be
changed from an electric arc furnace into a converter with few
manipulations and means which are structurally very simple. The
lance which is passed through the waste gas elbow is connected t
a positioning device which enables the lance head to move into
the vessel to a predeterminable depth.
The inserted lance may be formed as a simple oxygen lance, as a
simple burner or as a multifunction lance.
The flue gas elbow which is usual for the electric arc furnace
comprises shut-off members which are closed during the blowing
phase and the suction action through the waste gas elbow.
In order to charge liquid metal or liquid pig iron, it is
proposed that a bulge be provided at the lower part of the vessel
so that the liquid charge can easily be supplied.
When using a steel works device with two metallurgical vessels, just one lance or burner device and one waste gas elbow as" well as just one electrical supply via a support arm and an electrode or electrodes are required.
The respective functions of the vessels can be -changed by a simple and quick swiveling action by disposing the electrode F.upport arm and the flue gas elbow, including the lances or burner device, so as to avoid collisions. The disadvantageous action of opening the cover is no longer necessary, nor must any melt in the vessels be readied.
The swivel points of the electrode swiveling device and of the turning device for the waste gas elbow are disposed on a separating line which exactly separates the first furnace vessel from the second (extension) furnace vessel, even in the case of -an- electric furnace installation with just one furnace vessel.
An example of the invention is represented in the accompanying drawings, in which:
Figure 1 is a plan view
Figure 2 is a side view of the metallurgical vessel.
Figure 1 shows a plan view of a single furnace installation with the possibility of expanding it as a double furnace installation. In addition to the bulge 18 (28) and the tap hole 19 (29)
Flue gas elbows 51 (52) are connected to the covers 13 (23) and via a shut-off valve 53 (54) to a flue gas main 55. The suction parts 56 (57) of the bulges 18 (28) are also connected to the flue gas main 52.
The cover "l3 is detachably connected to a waste gas elbow 61, which can be swiveled by a turning device 63. The flue gas main 55 and a waste gas main 64 are brought together in an afterburning chamber 71. A lance 41, which is held by a lance support arm 42, is passed through the waste gas elbow 61.
An electrode 31 is Dosed thrush the cover centre 25 which electrode is connected via an electrode support arm 32 to an electrode swivelling device 33.
Figure 2 shows diagrammatically the two operating states, with the metallurgical vessel operating firstly as a converter and secondly as an. arc furnace. A lance 41 is secured to a lance support arm 42 and passed coaxially with the principal axis I of the vessel through a waste gas elbow 61 and the cover centre opening 16 into the-interior of^t4ae upp^r vessel part 12. The
upper part 12 and the lower part 17 together room one turn ace
vessel 11, which is closed by a cover 13. The cover 13 has a
cover centre opening 16, against which the mouth 62 of the waste
gas elbow 61 leans. The waste gas elbow 61 can be swiveled by a
turning device 63.
The lower vessel 17 comprises a tap hole 19, here the bottom tap,
for the metal melt.
The furnace shown on the left-hand side of the figure comprises
an electrode arm 32, to which in the present case three
electrodes 31 are secured, these being passed through the cover
centre 25, which closes the cover centre opening 26.
Furnace 1 and 2
11, 21 furnace vessel
12, 22 upper vessel part
13, 23 cover
14, 24 cover swivelling device
15, 25 cover centre
16, 26 cover centre opening
17, 27 lower part
18, 28 bulge
19, 29 tap hole Electrical supply
32 electrode support arm
33 electrode swivelling device Energy supply
42 lance support arm Flue gas conduction
51 flue gas elbow for 11
52 flue gas elbow for 21
53 shut-off device 51
54 shut-off device 52
55 flue gas main
56 suction part bulge 19
57 suction part bulge 2 9 Waste gas
61 waste gas elbow
52 mouth waste gas elbow
63 turning device
64 waste ^as main Gas utilization
71 afterburning chamber I principal axis of vessel • II separating line
1. A process for producing steel melts, comprising the steps of deoxidizing
an iron containing metal pool on a bottom of the vessel by adding Al/Si;
charging low carbon iron charge materials into the metal pool in the vessel;
supplying oxygen to the vessel to provide non-electric heat energy to the
metal pool and the charge materials; implementing refining of the charge
materials while simultaneously charging pig iron and adding lime into the
metal pool; removing up to 50% of slag that contains Si/02 and is formed by
the refining of the charge materials; suctioning off waste gases produced by
the refining; removing the slag, that contains phosphorous, at an end of
refining; furnishing heat energy via an electric arc to the metal pool and the
charge materials; suctioning off flue gases created by heating the charge
materials and metal pool with the electric arc; removing residual slag formed
by the heating of the charge materials and metal pool with the electronic arc;
and, tapping ferrous liquid melt fi-om the metal ix)ol and the heated charge
materials while maintaining a portion of the pool in the vessel to permit
restarting of the process, the steps being carried out so that the vessel first
acts as a converter and then as a direct arc furnace.
2. The process as claimed in claim 1, wherein the step of charging low
carbon iron charge materials includes charging scrap containing low carbon
3. The process as claimed in claim 1, wherein the refining is carried out by top blowing of oxygen.
4. The process as claimed in claim 1, wherein the refining includes burning one of an oxygen-natural gas mixture and an oxygen-oil mixture with an over extended flame in a hyperstoichiometeric manner.
5. The process as claimed in claim 1, wherein liquid pig iron and liquid iron charge material are charged into the metal pool at a ratio of liquid pig iron: Quid iron charge material of approximately 50:50.
6. The process as claimed in claim 2, wherein pig iron and scrap charge
material are charged into the metal pool at a ratio of scrap: pig iron in a range
of20:80 to 40:60.
7. The process as claimed in claim 2, wherein scrap charge material, liquid iron charge material and pig iron are charged at a ratio of scrap: pig iron: liquid iron charge material in a range of 10:60:30 to 10:40:50.
8. The process as claimed in claim 1, wherein the step of charging low carbon iron charge materials includes charging the low carbon charge materials in liquid form.
9. The process as claimed in claim 8, wherein the liquid low carbon charge materials are charged at a temperature of over 1300° C.
10. A device for producing steel melts by a process claimed in any of the preceding claims, the said device comprising at least one metallurgical vessel having an upper part, a lower part, a bottom, and an open top; a cover swingably arranged to close the top of the metallurgical vessel, the cover having a removable cover center with an opening; a flue gas elbow connected to the cover; a flush-off opening and a melt tap opening being arranged in the bottom of the vessel; a waste gas elbow having an opening configured to be placeable on the cover center opening; at least one lance configured to be insertable into an interior of the upper part of the metallurgical vessel through the cover center opening via the waste gas elbow; and means for famishing heat energy to the vessel via an electric arc.
11. The device as claimed in claim 10, wherein a gas purification unit is connected to the flue gas elbow.
12. The device as claimed in claim 10, wherein filling means is provided for filling the vessel with charge material.
13. The device as claimed in claim 10, wherein the lance is configured and arranged to run coaxial with a main axis of the metallurgical vessel, and so that a depth of submersion of the lance into the vessel is adjustable.
14. The device as claimed in claim 13, wherein an oxygen supply station is connected to the lance.
15. The device as claimed in claim 14, wherein filial supply means is connected to the lance.
16. The device as claimed in claim 15, wherein the fuel supply means is configured to supply one of natural gas and oil to the lance.
17. The device as claimed in claim 15, wherein the lance is configured as a burner.
18. Tlie device as claimed in claim 10, wherein a main flue gas hne and an after burning chamber are connected between the main flue gas hne and the waste gas elbow.
19. The device as claimed in claim 10, wherein the lower part of the metallurgical vessel is configured to downwardly curve for receiving liquid charges.
20. The device as claimed in claim 10, wherein two metallurgical vessels are provided, and a single electric power supply and a single oxygen or fuel station are connected to the vessels for powering the electric arc.
21. The device as claimed in claim 20, wherein the waste gas elbow is arranged along a hen that separates the two vessels, and further comprising turning means for permitting alternative placement of the opening of the waste gas elbow onto one of the cover center openings of the vessel covers.
22. A process for producing steel melts substantially as herein described with reference to the accompanying drawings.
23. A device for producing steel melts substantially as herein described with reference to the accompanying drawings.
|Indian Patent Application Number||1623/MAS/1995|
|PG Journal Number||30/2009|
|Date of Filing||11-Dec-1995|
|Name of Patentee||M/S. MANNESMANN AKTIENGESELLSCHAFT|
|Applicant Address||MANNESMANNUFER 2, D-40213 DUSSELDORF|
|PCT International Classification Number||C21B11/10|
|PCT International Application Number||N/A|
|PCT International Filing date|