CN104169442B - The vacuum refining method of molten steel - Google Patents
The vacuum refining method of molten steel Download PDFInfo
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- CN104169442B CN104169442B CN201380012488.3A CN201380012488A CN104169442B CN 104169442 B CN104169442 B CN 104169442B CN 201380012488 A CN201380012488 A CN 201380012488A CN 104169442 B CN104169442 B CN 104169442B
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- molten steel
- fuel
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- burner
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/068—Decarburising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
Abstract
A kind of method of refining of molten steel, it is by heating oxide powder being disposed in the flame formed in the burner of the top-blown spray gun front end on vacuum deaerator plant, and above-mentioned oxide powder is added to top blast on the liquid level of the molten steel in degassing vessel, make fuel and burning gas form flame in the mode meeting following formula to said burner supply: 0.4≤(G/F)/(G/F)
st≤ 1.1 (at this, G: burning gas feed speed (Nm
3/ min), F: fuel feed speed (Nm
3/ min), (G/F): oxygen fuel ratio (=burning gas feed speed/fuel feed speed), (G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel), the decline of molten steel temperature when adding Mn ore and Mn loss is suppressed to carry out carbonization treatment expeditiously thus, thus founding low-carbon high-manganese steel, or, suppress the decline of molten steel temperature when adding sweetening agent to carry out desulfurization process expeditiously thus founding low-sulfur steel.
Description
Technical field
The present invention relates to the vacuum refining method of molten steel, specifically, relate to the method by vacuum deaerator plant founding low-carbon high-manganese steel and low-sulfur steel.
Background technology
In recent years, the purposes variation of ferrous materials, situation about using under environment harsher than ever becomes many.The consequent, also increases than ever the requirement of the mechanical characteristics of product etc. and becomes strict.In this condition, for the purpose of the high strength of works, lighting, cost degradation, exploitation has the low-carbon high-manganese steel (following, to be also denoted as " low C height Mn steel ") having high strength and high working property concurrently, is widely used for the various field such as pipeline steel or automotive sheet.At this, above-mentioned low C height Mn steel refer to C concentration at below 0.05mass% and Mn concentration at the steel of more than 0.5mass%.
In addition, in steel making working procedure, as the manganese source of the cheapness for adjusting the Mn concentration in molten steel, there is manganese ore (following, also be denoted as " Mn ore ") or high carbon ferromanganese etc., when the above-mentioned low C height Mn steel of founding, carry out following operation: when carrying out Decarburising and refining by converter to molten iron, in converter, drop into Mn ore reduce, or in molten steel, add high carbon ferromanganese when converter tapping, thus the Mn concentration in molten steel is brought up to the concentration (for example, referring to patent documentation 1) of regulation.
But, when using the manganese source of these cheapnesss, in converter refining, the C concentration in molten steel cannot be reduced fully, or, cause the C concentration in the molten steel after tapping to rise because of the C contained by high carbon ferromanganese.Consequently, when C concentration may exceed the allowed band of low C height Mn steel, need the process implementing to remove C in addition from molten steel.
As the method for the C removed expeditiously in molten steel, there will be a known vacuum deaerator plants such as using RH vacuum degasser and the method for vacuum decarburization is carried out to the molten steel of non-deoxygenated state and under vacuo the oxygen sources (sending oxygen) such as molten steel injecting oxygen is carried out to the method etc. of decarburization.In above-mentioned vacuum decarburization, as the method using high carbon ferromanganese to be used as cheap manganese source, such as in patent documentation 2, the Decarburising and refining initial stage had at vacuum deaerator plant is proposed, high carbon ferromanganese is dropped into the method in molten steel, in addition, in patent documentation 3, propose have when by Fruit storage stove founding ultra-low carbon steel, arrive until drop into the method for high carbon ferromanganese during 20% of the carbonization treatment time.But if add oxygen when the vacuum decarburization process of the molten steel containing a large amount of Mn, then oxygen not only reacts with the C in molten steel and also reacts with Mn, therefore not only produces the oxidational losses of Mn and causes Mn yield to decline, and be difficult to the Mn concentration that controls accurately in molten steel.
In addition, for the oxygen source used in the carbonization treatment of vacuum deaerator plant and decarburization promotion method, such as, propose to drop into the solid oxygen such as expanded skin in oriented vacuum tank in patent documentation 4, suppress the oxidation of Mn thus and preferentially carry out the method for decarburizing reaction; In C amount when proposing oriented converter blowing out in patent documentation 5 and the molten steel of temperature limited system by vacuum degasser interpolation Mn ore to carry out the method for decarburization; In patent documentation 6 and patent documentation 7, proposing have when carrying out carbonization treatment by RH method to the steel after converter tapping, surperficial to MnO powder or Mn ore powder and the molten steel in carrier gas one in the same way vacuum tank top blast being carried out the method for carbonization treatment; In addition, propose to have in patent documentation 8 and via the nozzle be arranged on vacuum tank sidewall, the molten steel in the vacuum tank of Mn ore powder and carrier gas one RH vacuum degasser is in the same way blown into, carried out the decarburization of molten steel by the oxygen in Mn ore, and improve the method for Mn concentration.
On the other hand, along with high additive value and the use expansion of ferrous materials, the requirement improving material behavior is being increased always.As a method of this requirement of reply, advance the high purity of steel, specifically, advance extremely low sulfuration.The desulfurization of molten iron is generally carry out in molten iron stage and molten steel stage, and in the ultra-low sulphur steel for senior electro-magnetic steel plate or pipeline etc., the desulfurization in molten steel stage is necessary.For the method for refining ultra-low sulphur steel, proposed there is various scheme in the past, such as, injected the method for sweetening agent to the molten steel in ladle, after molten steel interpolation sweetening agent, carried out the method etc. stirred.But, because these methods are adding new operation between converter tapping to Fruit storage, therefore cause that the decline of molten steel temperature and manufacturing cost rise, degradation under productivity.
In order to address these problems, attempt, by making vacuum deaerator plant have desulfurizing function, merging, simplifying secondary refining operation.Such as, propose there is following method as using the sulfur method of vacuum deaerator plant: with the RH vacuum degasser possessing top-blown spray gun, sweetening agent and carrier gas are together jetted (projection) from top-blown spray gun to the molten steel liquid level in vacuum tank, thus by liquid steel desulphurization (for example, referring to patent documentation 9).
But such as, when adding the oxide powders such as solid oxygen or sweetening agent such as Mn ore in vacuum deaerator plant in carbonization treatment process, molten steel temperature declines because of latent heat needed for the sensible heat of oxide powder or thermolysis.For the method compensating this molten steel temperature and decline, exist before vacuum outgas, in operation, improve molten steel temperature method, in molten steel, add metal A l thus improve the method etc. of molten steel temperature by its combustion heat.But improve in front operation in the method for molten steel temperature, the loss of the refractory materials in front operation is comparatively large, causes cost to improve.In addition, add the method that heats up of metal A l and there is the Al oxide compound because generating and the degree of cleaning of molten steel are declined, or the drawback such as auxiliary material cost increase.
Therefore, decline while add the method for solid oxygen as suppressing molten steel temperature, propose to have oxide powder and on one side carry out heating with the flame of the burner (burner) being arranged on top-blown spray gun front end while the method (for example, referring to patent documentation 10,11) that projects on molten steel liquid level.In addition, as the method for adding sweetening agent, proposition has following method: together spray from top-blown spray gun front end by oxygen and burning gas and sweetening agent and form flame, by this flame by sweetening agent heating also melting, and make it arrive molten steel liquid level (for example, referring to patent documentation 12).
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 04-088114 publication
Patent documentation 2: Japanese Unexamined Patent Publication 02-047215 publication
Patent documentation 3: Japanese Unexamined Patent Publication 01-301815 publication
Patent documentation 4: Japanese Laid-Open Patent Publication 58-073715 publication
Patent documentation 5: Japanese Laid-Open Patent Publication 63-293109 publication
Patent documentation 6: Japanese Unexamined Patent Publication 05-239534 publication
Patent documentation 7: Japanese Unexamined Patent Publication 05-239526 publication
Patent documentation 8: Japanese Unexamined Patent Publication 01-092312 publication
Patent documentation 9: Japanese Unexamined Patent Publication 05-311231 publication
Patent documentation 10: Japanese Laid-Open Patent Publication 64-039314 publication
Patent documentation 11: Japanese Unexamined Patent Publication 07-041827 publication
Patent documentation 12: Japanese Unexamined Patent Publication 07-041826 publication
Summary of the invention
But, in order to promote decarburization or denitrogenation, dehydrogenation and the technology that projects disclosed in the method for oxide powder and patent documentation 10 and 11, to top condition when adding Mn ore as manganese source in vacuum deaerator plant without any research.Similarly, sweetening agent is heated by the flame of burner and the method for adding and the technology disclosed in patent documentation 12 to top condition when adding sweetening agent in vacuum deaerator plant without any research.
The present invention completes in view of the problems referred to above point existing for prior art, its object is to, a kind of casting method of low-carbon high-manganese steel is provided, in vacuum deaerator plant, when adding Mn ore as manganese source, molten steel temperature decline and Mn loss can be suppressed while carry out carbonization treatment expeditiously, and a kind of casting method of low-sulfur steel is provided, similarly in vacuum deaerator plant, when adding sweetening agent and carrying out desulfurization process, molten steel temperature can be suppressed to decline and to carry out desulfurization process expeditiously.
Contrivers etc., in order to solve above-mentioned problem, pay close attention to the reflex action of C and Mn when carrying out carbonization treatment by vacuum deaerator plant and the change behavior of molten steel temperature and repeatedly further investigate.Consequently, find following content thus develop the present invention: by making Mn ore to the adding conditional optimization of molten steel, above-mentioned problem can be solved, specifically, by the combustion conditions of the burner being arranged on top-blown spray gun front end being controlled at proper range, Mn ore is heated, reduction, and it is added to the molten steel top blast in vacuum tank, molten steel temperature can not be caused to decline, Mn can be added with high yield, and decarburization facilitation effect can be enjoyed, similarly, for sweetening agent, by being heated by the flame of the burner being arranged at top-blown spray gun front end, it also adds to the molten steel top blast in vacuum tank by this sweetening agent of melting, molten steel temperature can not be caused to decline carry out desulfurization process, in addition, preferably use the spray gun of appropriate structuring for this reason.
Namely, the present invention is a kind of method of refining of molten steel, it is by heating oxide powder at the burner of top-blown spray gun front end be disposed on vacuum deaerator plant or the flame of formation, and above-mentioned oxide powder is added to top blast on the liquid level of the molten steel in degassing vessel, the feature of the vacuum refining method of above-mentioned molten steel is, makes fuel and burning gas form flame in the mode meeting following formula to said burner supply:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: burning gas feed speed (Nm
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (=burning gas feed speed/fuel feed speed)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
The feature of the vacuum refining method of molten steel of the present invention is, above-mentioned oxide powder is Mn ore and/or CaO class sweetening agent.
In addition, the feature of the vacuum refining method of molten steel of the present invention is, from the nozzle of the centre hole front end that the axle core at above-mentioned top-blown spray gun is arranged, Mn ore and/or CaO class sweetening agent and carrier gas are together sprayed, from burner supply fuel and the burning gas of the multiple holes around front ends be disposed in around said nozzle, and igniting forms flame, heats above-mentioned oxide powder by this flame.
In addition, the feature of the vacuum refining method of molten steel of the present invention is, supplies more than any one in the geseous fuel of hydrocarbon class, the liquid fuel of hydrocarbon class and the solid fuel of carbon class and is used as above-mentioned fuel.
Invention effect
According to the present invention, except can decline suppressing molten steel temperature and with high Mn yield implement Mn ore in vacuum deaerator plant to molten steel interpolation except, decarbonization rate can also be improved, therefore, it is possible to high productivity and at low cost founding low-carbon high-manganese steel.In addition, according to the present invention, except molten steel temperature can be suppressed to implement the sweetening agent in vacuum deaerator plant with declining except the interpolation of molten steel, desulfuration efficiency can also be improved, therefore, it is possible to founding low-sulfur steel expeditiously.
Accompanying drawing explanation
Fig. 1 is the schematic vertical section of RH vacuum degasser.
Fig. 2 is the figure of the structure that top-blown spray gun used in the present invention is described.
Fig. 3 is the figure of the structure of the top-blown spray gun that prior art is described.
Fig. 4 is C concentration before representing Fruit storage and the chart of the relation of boiling decarbonization rate (rimmeddecarburizationrate).
Fig. 5 is the chart of the relation of C concentration before representing Fruit storage and Mn yield.
Fig. 6 represents the chart of the combustion conditions of burner on the impact of Mn yield.
Fig. 7 represents the chart of the combustion conditions of burner on the impact of desulfurization degree.
Embodiment
First, basic fundamental thought of the present invention and the experiment as its basis are described.
The main component of Mn ore is MnO
2and Mn
2o
3, the different multiple Mn oxide compound of the Oxidation Number such as MnO.When using this Mn ore as manganese source and when adding in molten steel as being used for promoting the oxygen source of decarburization, the different Mn oxide compound of the Oxidation Number in Mn ore passes through the C in molten steel, is reduced according to following (1) ~ (3) formula:
MnO
2+2
C→
Mn+2CO···(1)
Mn
2O
3+3
C→2
Mn+3CO···(2)
MnO+
C→
Mn+CO···(3)
According to above-mentioned (1) ~ (3) formula, the Oxidation Number of Mn oxide compound is higher, in order to the C amount of reducing required for Mn oxide compound is more.Therefore, be that Mn oxide compound that Oxidation Number is low is when making an addition in molten steel when making the Mn oxide compound in Mn ore, due to Mn ore reduction required for C amount reduce, even if so C concentration in molten steel is lower, also can expect to reduce fully Mn ore, and Mn yield is improved.
Therefore, invention personnel expect, when adding the Mn ore of powder from the top-blown spray gun be disposed on vacuum deaerator plant in molten steel, control the fuel combustion conditions (below also referred to as " combustion conditions of burner ") be arranged in the burner of above-mentioned top-blown spray gun front end, while heating Mn ore, the Mn Reduction of Oxide in Mn ore is added.
And, in order to confirm above-mentioned effect, not using in the laboratory experiment of molten steel, diversely changing the combustion conditions of burner and the input method of Mn ore of top-blown spray gun front end, carrying out the preliminary experiment carrying out top blast interpolation to ladle container.
Specifically, in above-mentioned preliminary experiment, as top-blown spray gun, use multiple lance tube by the heating of Mn ore and top blast interpolation, wherein the Mn ore of powder and carrier gas (Ar gas) together can spray from the nozzle of the centre hole front end being arranged at axle core by this multiple lance tube, further, flame can be formed from the burner ejection fuel of the multiple holes around front ends be disposed in around above-mentioned centre hole and burning gas.Now, for the feed speed of above-mentioned fuel and burning gas and with or without the heating carried out based on burner, carry out changing in the mode of table 1 and add, and investigated top blast add before and after the temperature variation of Mn ore and Mn ore in the change of composition of the different Mn oxide compound of Oxidation Number.In addition, in above-mentioned preliminary experiment, carrier gas uses Ar gas, and fuel uses propane gas, and burning gas uses pure oxygen.
Table 1
The result of above-mentioned preliminary experiment is recorded in table 1 in the lump.In addition, the G shown in table 1 is the feed speed (Nm of burning gas
3/ min), F is the feed speed (Nm of fuel
3/ min), (G/F) is oxygen fuel ratio (feed speed of burning gas is relative to the ratio of the feed speed of fuel), (G/F)
stfor the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.In addition, fuel be propane gas, (G/F) of burning gas when being pure oxygen
stbeing 5, that is, is 1Nm relative to the feed speed F of fuel
3/ min, the feed speed G of burning gas is 5Nm
3/ min.
Known according to above-mentioned table 1, when Mn ore and carrier gas are together added, can't help under the flame of burner of spray gun front end carries out the condition of the No.1 heated, any change is not found in Mn ore before and after dropping into, but under the condition of No.2 ~ 7 of being heated by Mn ore at the flame by burner and adding, the temperature of Mn ore rises, then has, in above-mentioned No.2 ~ 7, (G/F) in the combustion conditions of burner/(G/F)
stbe in No.4 ~ 7 in the scope of 0.4 ~ 1.1, the MnO in Mn ore
2and Mn
2o
3ratio reduce, the ratio of MnO increases, that is, the Mn oxide compound that Oxidation Number is high is reduced, and sex change is the Mn oxide compound that Oxidation Number is low, but, make (G/F)/(G/F)
stbe reduced in the No.8 of 0.3, because flame self does not generate, therefore identical with the condition of No.1, do not find change in the Mn ore before and after adding.
According to the above results, when the combustion conditions of the burner being formed at spray gun leading section is controlled at proper range, namely, when the combustion conditions of burner is controlled in hypoxgia side but not oxygen excess side, the flame formed is reductibility, promote the reduction of the Mn oxide compound in Mn ore, therefore, even if when the C amount in molten steel is less, Mn ore is also reduced sufficiently, thus Mn yield improves, in addition, when Mn ore heats by the flame by burner, risen by the temperature of Mn ore and suppress the decline of molten steel temperature, have again, the oxygen in Mn ore is utilized to promote decarburizing reaction by adding Mn.And known, also can expect effect same as described above when adding sweetening agent from spray gun front end.
The present invention is based on above-mentioned new technological thought and viewpoint and develop.
Next, the vacuum deaerator plant that the vacuum refinement of molten steel of the present invention uses is described.
For the vacuum deaerator plant that can be used in molten steel vacuum refining of the present invention, have RH vacuum degasser and DH vacuum degasser, VOD stove etc., wherein most is representational is RH vacuum degasser.Therefore, be described for RH vacuum degasser.
Fig. 1 is the vertical sectional view of typical RH vacuum deaerator plant.
This RH vacuum deaerator plant comprises the ladle 2 of storage molten steel 1 and molten steel is carried out to the degassed portion 3 of Fruit storage (hereinafter referred to as " degassed process ").Above-mentioned degassed portion 3 comprises molten steel importing inside and the vacuum tank 4 carrying out degassed process and the not shown exhaust equipment be connected with vacuum tank 4.The upper side of vacuum tank 4 is provided with the venting port 7 be connected with exhaust equipment and the input port (chute) 8 of adding the auxiliary materials such as alloy raw material (composition adjustment agent) or solvent.
In addition, be equipped with two immersion tubes 5 and 6 in the bottom of vacuum tank 4, the immersion tube (being 5 in Fig. 1) of a side is wherein connected with pipe arrangement 10, and this pipe arrangement 10 is blown into the recycle stream for making molten steel 1 form circulation in immersion tube.And, when carrying out degassed process, above-mentioned two immersion tubes are made to be immersed in the molten steel in ladle, be exhausted in vacuum tank 4 by not shown exhaust equipment, while the molten steel 1 in ladle 2 is imported in vacuum tank 4, in immersion tube 5, supply recycle stream rare gas elementes such as () Ar gas via above-mentioned pipe arrangement 10, make produce bubble in immersion tube 5 and make bubble increase.Thus, molten steel in immersion tube 5 also together rises with recycle stream and flow in vacuum outgas groove, after degassed process, the immersion tube (being 6 in Fig. 1) formed through the opposing party declines and returns the circulation of the molten steel in ladle, carries out degassed process thus.
Further, be equipped with top-blown spray gun 9 on the top of vacuum tank 4 with the form inserted in vacuum tank 4 from top.This top-blown spray gun 9 is multiple lance tubes, and it is equipped: oxygen and the oxide powder such as Mn ore or CaO class sweetening agent and transport their passage of carrier gas; At the nozzle that this Channel front end is jetted to the surface of molten steel by above-mentioned substance ejection and by them; Fuel and for making the passage of the burning gas of this fuel combustion; And make above-mentioned fuel combustion at this Channel front end and form the burner of flame.
In addition, above-mentioned top-blown spray gun 9 links with the not shown hopper (hopper) storing auxiliary material, together supplies oxide powder and the carrier gas such as Mn ore or CaO class sweetening agent.As above-mentioned CaO class sweetening agent, be mainly used in unslaked lime (CaO) or Wingdale (CaCO
3), slaked lime (Ca (OH)
2), the fluorite (CaF of mixing about 5 ~ 30mass% in rhombspar (CaO-MgO) etc.
2) or aluminum oxide (Al
2o
3) etc. the material of CaO scorification promotor.In addition, above-mentioned carrier gas uses the rare gas elementes such as Ar gas or nitrogen usually.
In addition, above-mentioned top-blown spray gun 9 links with not shown fuel feed pipe and burning gas supply pipe, as above-mentioned fuel, at least one in the geseous fuel of the hydrocarbon classes such as supplying propane gas or Sweet natural gas, the liquid fuel of the hydrocarbon class such as diesel oil or kerosene, the carbon class solid fuel such as coke or coal, in addition, as burning gas, the oxygen-containing gas of oxygen gas-supplying, oxygen enrichment air, air etc.Further, above-mentioned top-blown spray gun 9 carries out water-cooled, therefore also link with the not shown water coolant supplying drainage for supplying/discharging water-cooled water coolant used.
At this, the top-blown spray gun that the vacuum refinement of molten steel of the present invention uses is described.
Fig. 2 is the figure of the example representing the preferred top-blown spray gun that the present invention is used, and (a) is vertical sectional view, and (b) is upward view.This top-blown spray gun comprises: passage (hereinafter referred to as " oxygen channel " or " powder, carrier gas passage ") 11, and it doubles as oxide powder, the carrier gas passage of the oxygen channel of the oxygen that supply is jetted to molten steel and the carrier gas of supply oxide powder and oxide powder; Internal water cooling cylindrical shell 13, it possesses at axle center part " centre hole " that be made up of the nozzle 12 of the front end and spray gun front end that are arranged on this passage 11; Outside water-cooled cylindrical shell 14, it surrounds this internal water cooling cylindrical shell 13 around; And many " holes around ", it is included in and supplies the passage 15 of fuel or burning gas between above-mentioned internal water cooling cylindrical shell 13 and outside water-cooled cylindrical shell 14 and be arranged on the burner 16 of this Channel front end and spray gun front end.Above-mentioned holes around is dual pipe structure, and fuel moves at interior pipe effluent, and burning gas moves at outer tube effluent, but also can exchange the passage of fuel and the passage of burning gas.
And, from the oxide powder etc. that the nozzle 12 of the front end of above-mentioned powder, carrier gas passage 11 sprays, heated by the flame formed in the burner 16 of spray gun front end, or heated, reduce, or heated, melting, and in vacuum tank molten steel liquid level winding-up.
In addition, in fig. 2, in 8 holes around be used as the pilot burner (pilotburner) 17 of the fuel ignition of ejection, therefore burner radical is 7.But, the fuel supplied from the burning gas passage of burner 16 and from the burning gas (oxidizing gas) of burning gas passage supply because respective jet hole mixes instantaneously close to (repetition), be within the scope of combustion limits, but because the envrionment temperature in vacuum tank is high, so also take fire even without portfire, form flame in the below of top-blown spray gun 9.Therefore, usually do not need pilot burner, but also can arrange.
At this, the position relationship of the above-mentioned centre hole of top-blown spray gun front end and the position relationship of holes around and nozzle 12 and burner 16 is adjusted and is come also to have no relations, but because the flame by burner is by can heated oxide thing powder expeditiously containing the words encased around the jet flow of oxide powder, so preferably as illustrated in fig. 2, arrange nozzle at the axle core of spray gun, and arrange burner around it.
In addition, the shape being arranged at the nozzle 12 of the centre hole front end of top-blown spray gun in Fig. 2 is the Laval-cavity nozzle be made up of this two cones of part of the part of reduced cross-sectional and enlargement in section, but also can be the nozzle of rectilinear form.In addition, that two cones reducing part and expansion section s in Laval-cavity nozzle are connected, that cross section is the narrowest position, is commonly called aditus laryngis.
The top-blown spray gun of the Fig. 2 be made up of this structure possesses oxygen channel, powder, carrier gas passage, fuel channel and burning gas passage, therefore, it is possible to carry out the heating of dirt settling in the heating (intensification) of the molten steel in the preheating of vacuum tank, vacuum tank and vacuum tank, removing and to all process such as molten steel winding-up powder.
In addition, above-mentioned top-blown spray gun 9 used in the present invention is not limited to the scope of above-mentioned explanation, such as, also can arrange multiple burner around top-blown spray gun and use the Mn ore heating that these burners will be blown into from top-blown spray gun.Further, the top-blown spray gun and burner that add for Mn ore can also be provided separately.
Next, the casting method of the low-carbon high-manganese steel using the RH vacuum degasser of above-mentioned explanation is described.
First, be loaded into the maintenance container such as molten iron boiler or torpedo car (torpedocar) by from the molten iron after blast furnace casting or after transporting container, transporting to the steel operation processed of carrying out Decarburising and refining.Usually, more to the situation of preliminary treatment such as molten iron such as molten iron enforcement desulfurization or dephosphorization etc. in this conveyance way, in the present invention, even if when not needing molten iron preliminary treatment in ingredient standard, also preferably implement molten iron preliminary treatment.Be so why because, in converter, Mn ore is added as manganese source, when not carrying out molten iron preliminary treatment and particularly not carrying out dephosphorization treatment, need during blowing in converter side by side to carry out dephosphorization with decarburization, owing to adding CaO class fusing assistant in a large number for this reason, so make the slag amount of converter increase, the manganese amount be assigned in slag increases and causes Mn yield to decline.
In ensuing steel operation processed, after molten iron is loaded converter, Mn ore is added as manganese source, also add a small amount of unslaked lime equal solvent as required, top blast and/or BOTTOM OXYGEN carry out decarburization blowing, make the molten steel of predetermined component composition, then, the state maintaining non-deoxidation keeps container tapping directly to molten steel such as ladles.Now, the alloy iron system manganese source of the cheapnesss such as the high carbon ferromanganese of specified amount can also be added.
In addition, due in above-mentioned steel operation processed, the manganese source that Mn ore or high carbon ferromanganese etc. are cheap is used, so the carbon concentration in molten steel must uprise, even if but in this case, the C concentration in the molten steel after the adjustment of Mn concentration also preferably suppresses at below 0.2mass%.If C concentration is more than 0.2mass%, the carbonization treatment time in the vacuum deaerator plant of then subsequent handling is elongated, not only productivity declines, and in order to compensate the reduction of the molten steel temperature caused along with the prolongation of carbonization treatment time, produce the needs improving tapping temperature, the refractory materials cost increase cause the decline of iron yield, causing because refractory wear amount increases, therefore not preferred.
Next, from the steel of converter tapping to RH vacuum degasser or the conveyance of the vacuum deaerator plant such as DH vacuum degasser, VOD stove, the degassed process such as carbonization treatment are implemented.Below, the casting method of the low-carbon high-manganese steel using the RH vacuum degasser shown in Fig. 1 is described.
In the RH vacuum degasser shown in Fig. 1, while vacuum decarburization process (also this process being called below " boiling process (rimmingtreatment) ") is carried out to the molten steel 1 of non-deoxygenated state, in this boiling process, add Mn ore from top-blown spray gun 9 top blast.Now, above-mentioned Mn ore needs to heat at the flame by the burner being formed at top-blown spray gun 9 leading section, reduction jetting to the liquid level of molten steel adds.Specifically, the burner 16 of fuel to spray gun front end supplies and this fuel is sprayed by the fuel channel via the holes around be arranged on top-blown spray gun 9, via burning gas passage, the burner 16 of burning gas to spray gun front end supplied and this burning gas is sprayed, forming flame in the burner by igniting.And, spray Mn ore via the powder of medium pore, carrier gas passage 11 from the nozzle 12 of spray gun front end, the Mn ore of ejection heat by the flame of said burner, reduce also top blast interpolation.In addition, preferably when starting to add Mn ore, flame is formed in the burner in advance.
At this, in order to heat, reducing the flame that above-mentioned Mn ore is formed in the burner of spray gun front end, fuel and burning gas demand fulfillment following formula:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: burning gas feed speed (Nm
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (=burning gas feed speed/fuel feed speed)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
As mentioned above, if (G/F)/(G/F)
stmore than 1.1, then the oxidisability grow of flame, although Mn ore is heated, does not carry out the reduction of the Mn oxide compound in Mn ore.On the other hand, if (G/F)/(G/F)
stlower than 0.4, then because flame self can not be formed, so also Mn ore cannot be heated.Preferably (G/F)/(G/F)
stmore than 0.4 and lower than in the scope of 1.0.
By heating like this and adding Mn ore, the molten steel temperature that the interpolation along with Mn ore can be suppressed to cause declines (temperature loss).In addition, because the Mn ore being satisfied the flame heating of above-mentioned combustion conditions is reduced and adds in molten steel, so promote the reduction reaction of Mn ore, Mn yield improves, therefore, it is possible to reduce the addition of Mn alloy.Further, because the oxygen in Mn ore plays a role as solid oxygen, promote decarburizing reaction, so the interpolation of Mn ore can shorten the boiling treatment time, boost productivity.
In addition, in above-mentioned boiling process, also can be to heat and after adding Mn ore, the nozzle 12 via oxygen channel 11 and front end thereof sprays oxygen, and to molten steel winding-up, promoting decarburization or heating molten steel thus.In addition, when above-mentioned carbonization treatment or hyperthermic treatment, because do not use burner, so the rare gas element such as nitrogen or Ar gas that preferably circulates in fuel channel and burning gas passage, the obturation of the burner caused because to splash etc. is prevented.
When carrying out the above-mentioned boiling process of specified time and after the C concentration in molten steel reaches the prescribed value of below ingredient standard value, add the strong reductors such as Al from material pouring inlet 8 to molten steel 1 to reduce the oxyty (deoxidation) molten steel, terminate boiling process.In addition, when the molten steel temperature after process of seething with excitement terminates is lower than the temperature such as cast continuously required by the subsequent handlings such as operation, also Al can be added from material pouring inlet to molten steel further, and from above-mentioned top-blown spray gun to the surface of molten steel winding-up oxygen (giving oxygen), Al is burnt, makes molten steel temperature increase thus.
Add reductor and molten steel 1 after deoxidation in several minutes thereafter, proceed the circulation (this process being called " calm process ") of molten steel, and as required, drop into the composition adjustment agent (alloying constituent) such as Al, Si, Mn, Ni, Cr, Cu, Nb, Ti from material pouring inlet 8 to molten steel 1 and molten steel component be adjusted to the compositing range of regulation, afterwards, make vacuum tank 4 return to normal atmosphere, terminate degassed process.
Next, the casting method of the low-sulfur steel using the RH vacuum degasser of above-mentioned explanation is described.In addition, molten iron is from blast furnace casting, through bessemerizing, tap and transporting to the process of RH vacuum degasser identical with the casting method of above-mentioned low-carbon high-manganese steel, so omit the description.
For the molten steel being in non-deoxygenated state transported to RH vacuum degasser, that carry out the specified time as required, carry out decarburization to molten steel injecting oxygen via the oxygen channel 11 of top-blown spray gun 9 and the nozzle 12 of its front end boiling process, after the C concentration in molten steel reaches the prescribed value of below ingredient standard value, add the strong reductors such as Al from material pouring inlet 8 to molten steel 1 to reduce the oxyty (deoxidation) molten steel, terminate boiling process.
In addition, when the molten steel temperature after process of seething with excitement terminates, namely after deoxidation is lower than the temperature such as cast continuously required by the subsequent handlings such as operation, also Al can be added from material pouring inlet to molten steel further, and from above-mentioned top-blown spray gun to the surface of molten steel winding-up oxygen (giving oxygen), Al is burnt, makes molten steel temperature increase thus.In addition, also can be, in the same manner as the casting method of above-mentioned low-carbon high-manganese steel, while the molten steel 1 of non-deoxygenated state being carried out to boiling process, add Mn ore from top-blown spray gun 9 top blast.
Next, while the molten steel winding-up CaO class sweetening agent after from top-blown spray gun 9 to above-mentioned deoxidation, heat this CaO class sweetening agent by the flame formed in burner 16 and make its melting, and winding-up is added on the liquid level of molten steel, carries out desulfurization process.Specifically, fuel channel via the holes around be arranged on top-blown spray gun 9 supplies fuel to the burner 16 of spray gun front end and this fuel is sprayed, supply burning gas via the burner 16 of burning gas passage to spray gun front end and this burning gas is sprayed, and form flame by igniting, simultaneously, spray CaO class sweetening agent via the powder of medium pore, carrier gas passage 11 from the nozzle 12 of spray gun front end, the CaO class sweetening agent of this ejection is heated by the flame of said burner, melting top blast add.In addition, preferably when starting to add CaO class sweetening agent, flame is formed in the burner in advance.
At this, in order to heat, the above-mentioned sweetening agent of melting and the flame that formed in the burner of spray gun front end, fuel and burning gas demand fulfillment following formula:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: burning gas feed speed (Nm
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (=burning gas feed speed/fuel feed speed)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
This is because, if (G/F)/(G/F)
stmore than 1.1, then the oxidisability grow of flame, although sweetening agent is heated, does not carry out reduction reaction and desulphurization reaction.On the other hand, if (G/F)/(G/F)
stlower than 0.4, then because flame self can not be formed, therefore also sweetening agent cannot be heated.Preferably (G/F)/(G/F)
stmore than 0.4 and lower than 1.0 scope.
By heating like this and adding sweetening agent, the temperature of the molten steel caused along with the interpolation of sweetening agent can be suppressed to decline (temperature loss).In addition, because the flame meeting above-mentioned combustion conditions can not form peroxidation environment, therefore, it is possible to promote reduction reaction and desulphurization reaction, improve desulfurization degree.
In addition, when not needing the carbonization treatment in RH vacuum degasser in ingredient standard, also when molten steel is tapped from converter to ladle, metal A l can be added to make steel liquid deoxidation in the molten steel stream in tapping.Now, except Al, lime or the fusing assistant containing lime can also be added in tapping stream.For tapping to the molten steel in ladle, the rear slag on molten steel add the slag modifiers such as Al, implement, by the slag modification of the Mn oxide such as ferriferous oxide or the MnO reduction such as the FeO in slag, then to transport to RH vacuum degasser.
Molten steel 1 after deoxidation is carried out for the above-mentioned reductor of interpolation, implemented to make molten steel circulation and the calmness process carrying out degassed process by RH vacuum degasser afterwards, then drop into the composition adjustment agent (alloying constituent) such as Al, Si, Mn, Ni, Cr, Cu, Nb, Ti from material pouring inlet 8 to molten steel 1 as required and molten steel component be adjusted to the compositing range of regulation, make vacuum tank 4 return to normal atmosphere afterwards, terminate degassed process.
In addition, although be illustrated the casting method of the low-carbon high-manganese steel and low-sulfur steel that use RH vacuum degasser in above-mentioned explanation, even if but when using other vacuum deaerator plants such as DH vacuum degasser or VOD stove, also can founding low-carbon high-manganese steel and low-sulfur steel according to the method described above.
Embodiment 1
After the molten iron preliminary treatment of the molten iron from blast furnace casting being carried out to dephosphorization, desulfurization, blown by 350 tons of converters, make and there is composition consist of C:0.03 ~ 0.09mass%, below Si:0.05mass%, Mn:0.1 ~ 0.85mass%, the steel of below P:0.03mass%, below S:0.003mass%.In addition, in above-mentioned converter, add Mn ore and adjust Mn concentration as manganese source.
Molten steel after bessemerizing is tapped directly to ladle under the state of non-deoxidation, and conveyance is to the RH vacuum degasser possessing top-blown spray gun, under non-deoxygenated state, directly implement degassed process, wherein this degassed process is along with the boiling process carrying out vacuum decarburization process.In addition, when arriving RH vacuum degasser in molten steel O concentration in the scope of 0.03 ~ 0.07mass%.
In above-mentioned boiling process, the flow making recycle stream (Ar gas) is 1500NL/min, make the vacuum tightness of arrival vacuum tank be 6.7 ~ 40kPa (under each condition fixing), and make the kind of used top-blown spray gun, combustion conditions (((G/F)/(G/F) with or without the burner of the interpolation of Mn ore and addition means, spray gun front end
st)) and with or without send oxygen as shown in table 2 change.
In addition, the granularity of the Mn ore of interpolation is 5 ~ 20mm, and manganese content is approximately 58mass%, and the interpolation speed of Mn ore is fixed as 100kg/min, and the interpolation time is fixed as 10min, and total addition level is fixed as 1000kg.
In addition, the target component of the molten steel after boiling process is C:0.002 ~ 0.003mass%, Mn:0.5 ~ 1.2mass%, when Mn concentration is too low after process of seething with excitement terminates, adds manganese metal and carries out the adjustment of Mn concentration.
In addition, when seething with excitement process when hypoxgia, from the nozzle of top-blown spray gun front end to the surperficial injecting oxygen (sending oxygen) of molten steel while carry out decarburization.
In addition, as the top-blown spray gun of above-mentioned RH vacuum degasser, use the spray gun shown in the spray gun shown in applicable Fig. 2 of the present invention and Fig. 3 similar with the spray gun disclosed in patent documentation 10 these two kinds.The spray gun of Fig. 3 is provided with the fuel gas supply holes 24 be connected with burning gas passage 23 on the expansion mouth 22 be connected with aditus laryngis 21, wherein aditus laryngis 21 is connected with the oxygen channel 20 of the axle core being arranged at spray gun, further, this spray gun sprays the structure of Mn ore from the squit hole 26 of powder, carrier gas passage 25 front end.
And, when using the spray gun shown in Fig. 2, the interpolation of Mn ore by via centre hole and powder, carrier gas passage 11 and nozzle 12 by Mn ore and carrier gas (Ar gas) in the same way the surperficial top blast of molten steel carry out.In addition, when forming flame in the burner of top-blown spray gun front end, make LNG with 240Nm as fuel
3/ hr supplies, and makes pure oxygen at 120 ~ 600Nm in addition as burning gas
3change in the scope of/hr and supply, thus making combustion conditions ((G/F)/(G/F) of burner
st) change.In addition, (G/F) in this situation
stbe 2 (be 1Nm relative to the feed speed F of fuel
3the situation of/min, the feed speed G of burning gas is 2Nm
3/ min).In addition, the formation time of flame is all 10min (fixing) under any one condition.
On the other hand, when using the spray gun shown in Fig. 3, by while spray burning gas (oxygen) via oxygen channel 20, while via powder, carrier gas passage 25 by top blast in Mn ore and carrier gas (Ar gas) in the same way molten steel liquid level, carry out the interpolation of Mn ore.In addition, when the front end of top-blown spray gun forms flame, make LNG with 240Nm as fuel
3/ hr supplies, and makes pure oxygen with 470Nm as burning gas
3/ hr supplies.In addition, the formation time of flame is 10min.
Table 2
Decarbonization rate when the Mn yield in the Mn ore added in the Mn concentration of (but, before adding concentration adjustment that manganese metal carries out), boiling process before describing degassed process in table 2 in the lump after the molten steel component (C, Mn) of (boiling process before), boiling process, boiling process and the molten steel temperature before and after boiling process poor.In addition, the decarbonization rate described in above-mentioned table 2 is the average decarbonization rate that the decarburized amount from during arrival RH to boiling process terminates obtained divided by the boiling treatment time.In addition, molten steel temperature difference is positive situation is represent that molten steel temperature rises, for negative situation represents that molten steel temperature declines.
According to the known following content of table 2.
First, No.16 ~ 18 are the top-blown spray guns using Fig. 2, form flame, do not add the comparative example of Mn ore during boiling process in spray gun front end, although molten steel temperature rises, but decarbonization rate is 0.0033 ~ 0.0036mass%/min.On the other hand, the decarbonization rate that with the addition of in No.1 ~ 15 of Mn ore is 0.0040 ~ 0.0052mass%/min, and the known interpolation by Mn ore, facilitates decarburization.Think this is because Mn oxide compound in Mn ore plays the effect of solid oxygen effectively, facilitate the decarburizing reaction of molten steel.In addition, in the comparative example of these No.16 ~ 18, the hypoxgia required for decarburization, has to carry out sending oxygen, therefore produces Mn loss.
Next, the example adding Mn ore is analyzed.
No.13 ~ 15 are the top-blown spray guns using Fig. 2, in vacuum tank, the comparative example of Mn ore is not added heatedly from auxiliary material input port (8 of Fig. 1), the sensible heat added due to adjoint Mn ore or the temperature loss caused by decomposition heat (latent heat), molten steel temperature declines more than 30 DEG C, decarbonization rate is only 0.004mass%/min level, and Mn yield is only in 40 ~ 50% levels.
In addition, No.10 ~ 12 be use the top-blown spray gun shown in Fig. 2 but without burner flame heating Mn ore carry out the comparative example of top blast interpolation, in the same manner as above-mentioned No.13 ~ 15, due to the sensible heat that adds with Mn ore or latent heat and make molten steel temperature decline to a great extent, Mn yield is step-down in the same manner as above-mentioned No.13 ~ 15 also.
On the other hand, No.19 is the top-blown spray gun using the prior art shown in Fig. 3, is heated and the example of interpolation by Mn ore by the flame formed in spray gun front end.In this example, molten steel temperature rises more than 10 DEG C.Think this is because by the heating of Mn ore is added, temperature loss can be reduced, thus makes thermo-efficiency improve.In addition, Mn yield is also increased to close to 80%.Think this is because by heating Mn ore by the flame of reductibility, Mn ore reduction is added.
Have again, No.1 ~ 6 use the top-blown spray gun shown in Fig. 2, by the heating of the flame of Mn ore burner while the example of top blast interpolation, molten steel temperature after boiling process rises more than 9 DEG C, decarbonization rate is all up to more than 0.048mass%/min, and the Mn yield in Mn ore is also more than 80%.
At this, although the combustion conditions of the example burner of the example of No.4 and No.19 ((G/F)/(G/F)
st) identical, but the molten steel temperature ascending amount of the example of No.4, decarbonization rate, Mn yield are all comparatively outstanding.Think that the producing cause of this difference is as follows, Mn ore and burning gas and vapor permeation spray in spray gun front end by the top-blown spray gun of the Fig. 3 used in No.19, relative to this, the top-blown spray gun of the Fig. 2 used in No.4 is from the nozzle ejection Mn ore of spray gun front end, and utilize the flame being disposed in burner around nozzle encase this jet flow and heated by Mn ore, therefore the spray gun of Fig. 2 can heat expeditiously, reduce Mn ore.
On the other hand, No.7 is combustion conditions ((G/F)/(G/F) except burner
st) higher than beyond the scope of the invention, the comparative example identical with the example of No.1 ~ 6, because flame is not reductibility, Mn ore is not reduced, although therefore molten steel temperature rises, the yield of Mn is lower in the same manner as No.13 ~ 15.
On the contrary, No.8,9 is except ((G/F)/(G/F)
st) lower than beyond scope of the present invention, the comparative example identical with the example of No.1 ~ 6, oxygen because of supply is not enough and can not form flame, thus Mn ore is not heated, therefore, due to Mn ore add sensible heat or latent heat caused by temperature loss and molten steel temperature is declined, Mn yield is also identically with No.13 ~ 15 lower.
At this, Fig. 4 represents in the example of No.1 ~ 6 and the comparative example of No.7 ~ 15, the relation of RH C concentration before treatment and decarbonization rate, and Fig. 5 represents in the example of above-mentioned No.1 ~ 6 and the comparative example of No.7 ~ 15, the relation of RH C concentration before treatment and Mn yield.Known according to these two figure, when RH C concentration before treatment at par, the decarbonization rate of example higher than comparative example, and Mn yield improve.Think this is because, as mentioned above, when Mn ore heats by the flame by best combustion condition and top blast adds, because Mn ore arrives the reduction carrying out Mn oxide compound before molten steel, therefore the C quantitative change needed for reduction of Mn ore is few.Consequently, even if when RH C before treatment concentration is lower, also can reduce Mn ore fully, the oxygen in Mn ore can work fully as solid oxygen.That is, think in a comparative example, when RH C before treatment concentration is lower, for reducing, the C of Mn ore is not enough, and Mn yield declines.
In addition, Fig. 6 represent by the flame of burner Mn ore to be heated and in the example of No.1 ~ 6 of adding and the comparative example of No.7 ~ 9, ((G/F)/(G/F)
st) with the relation of Mn yield.According to this figure, ((G/F)/(G/F)
sttime in the scope of 0.4 ~ 1.1, Mn yield reaches more than 80%, wherein at ((G/F)/(G/F)
stbe more than 0.4 and lower than in the scope of 1.0 time, Mn yield can reach the high value of more than 90%.
According to above result, by using applicable spray gun of the present invention and forming flame to be applicable to condition of the present invention in the burner of spray gun front end, and with this by the heating of Mn ore, reduction also top blast interpolation, the decline of molten steel temperature can not only be suppressed, add Mn with high yield, decarbonization rate can also be improved, therefore, it is possible to high-level efficiency and implement the founding of low-carbon high-manganese steel at low cost.
Embodiment 2
After molten iron from blast furnace casting being carried out the molten iron preliminary treatment of dephosphorization, desulfurization, blown by 350 tons of converters, make and there is composition consist of C:0.03 ~ 0.09mass%, below Si:0.05mass%, Mn:0.1 ~ 0.85mass%, the steel of below P:0.03mass%, S:0.0037 ~ 0.0042mass%.
Molten steel after bessemerizing is tapped directly to ladle under the state of non-deoxidation, and conveyance is to the RH vacuum degasser possessing top-blown spray gun, directly degassed process is implemented, the wherein adjoint boiling process carrying out vacuum decarburization process in this degassed process under non-deoxygenated state.When arriving RH vacuum degasser in molten steel O concentration in the scope of 0.03 ~ 0.07mass%.
In above-mentioned boiling process, the flow making recycle stream (Ar gas) is 1500NL/min, the vacuum tightness of arrival vacuum tank is made to be 6.7 ~ 40kPa (fixing under each condition), while send oxygen while carry out boiling process by oxygen to the surface of molten steel from the nozzle of top-blown spray gun front end, after C concentration in molten steel reaches the prescribed value of below ingredient standard value, add Al to molten steel and carry out deoxidation, terminate boiling process.Thereafter, add CaO class sweetening agent to above-mentioned molten steel, implement desulfurization process.In addition, above-mentioned sweetening agent uses the CaO-Al that granularity is below 2mm
2o
3pre-molten fusing assistant, the interpolation speed of sweetening agent is fixed as 100kg/min, and the interpolation time is fixed as 10min, and total addition level is fixed as 1000kg.
Now, the adding conditional (with or without burner heating) of sweetening agent, combustion conditions (((G/F)/(G/F) of burner
st)) change as shown in table 3ly.In addition, about sweetening agent, use the top-blown spray gun shown in Fig. 2 via centre hole and powder, carrier gas passage 11 and nozzle 12, by sweetening agent and carrier gas (Ar gas) in the same way surperficial winding-up of molten steel add.
In addition, when forming flame in the burner of top-blown spray gun front end, with 240Nm
3/ hr supply as the LNG of fuel, and makes pure oxygen as burning gas at 120 ~ 600Nm
3alternatively supply in the scope of/hr, make combustion conditions ((G/F)/(G/F) of burner thus
st) change.In addition, (G/F) in this situation
stbe 2 (be 1Nm relative to the feed speed F of fuel
3the situation of/min, the feed speed G of burning gas is 2Nm
3/ min).
Table 3
Describe in the lump in table 3 degassed process before and after molten steel in S concentration and the desulfurization degree of trying to achieve according to its value, sweetening agent projection before and after molten steel temperature poor.In addition, for positive situation, molten steel temperature difference represents that molten steel temperature rises, for negative situation represents that molten steel temperature declines.
According to the known following content of table 3.
No.9 uses the top-blown spray gun shown in Fig. 2, but can't help burner flame heating sweetening agent carry out the comparative example of top blast interpolation, due to the sensible heat added with sweetening agent, molten steel temperature is declined to a great extent, desulfurization degree is also low reaches 60% level.
On the other hand, No.1 ~ 6 are the examples using the top-blown spray gun shown in Fig. 2 and sweetening agent is carried out heatedly top blast interpolation by the flame of burner, the temperature loss almost do not caused because sweetening agent adds.Think this is because, by being heated by sweetening agent and adding, temperature loss is reduced, and thermo-efficiency is improved.In addition, desulfurization degree also can reach more than 78%.Think this is because, the flame of burner is reductibility, thus can promote the desulphurization reaction of molten steel.
On the other hand, No.7 is combustion conditions ((G/F)/(G/F) except burner
st) higher than beyond scope of the present invention, the comparative example identical with the example of No.1 ~ 6, although molten steel temperature rises, desulfurization degree is low reaches 60% level.Think this is because, because flame is not reductibility, so fail to carry out the desulphurization reaction of reduction reaction and molten steel.
On the contrary, No.8 is combustion conditions ((G/F)/(G/F) except burner
st) lower than beyond scope of the present invention, the comparative example identical with the example of No.1 ~ 6, the oxygen because of supply is not enough and can not form flame, and sweetening agent is not heated, therefore because temperature loss makes molten steel temperature decline to a great extent.But, due to unburned reducing gas supply sweetening agent, so desulfurization degree is up to 88.1%.
At this, Fig. 7 represent heat sweetening agent by the flame of burner and carry out example that add, No.1 ~ 6 and No.7,8 comparative example in, ((G/F)/(G/F)
st) with the relation of desulfurization degree.According to this figure, ((G/F)/(G/F)
sttime below 1.1, desulfurization degree reaches more than 78%, wherein at ((G/F)/(G/F)
stbe more than 0.4 and lower than in the scope of 1.0 time, desulfurization degree can reach the high value before and after 90%.In addition, although even if (G/F)/(G/F)
stbe 0.3 also can reach higher desulfurization degree, but under this condition, as mentioned above, can not form flame, molten steel temperature decline to a great extent, so not preferred.
According to above result, by using applicable spray gun of the present invention and forming flame to be applicable to condition of the present invention in the burner of spray gun front end, and with this, sweetening agent is heated, melting top blast add, the decline of molten steel temperature can be suppressed, and desulfurization degree can be improved, therefore, it is possible to implement the founding of low-sulfur steel expeditiously.
Description of reference numerals
1: molten steel
2: ladle
3: degassed portion
4: vacuum tank
5,6: immersion tube
7: venting port
8: auxiliary material input port (chute)
9: top-blown spray gun
10: recycle stream supplying tubing
11: oxygen channel or powder, carrier gas passage
12: nozzle
13: internal water cooling cylindrical shell
14: outside water-cooled cylindrical shell
15: fuel, burning gas passage
16: burner
17: pilot burner
20: oxygen channel
21: aditus laryngis portion
22: expansion mouth
23: fuel gas channel
24: fuel gas supply holes
25: powder, carrier gas passage
26: powder, carrier gas squit hole
Claims (5)
1. the vacuum refining method of a molten steel, it is by heating oxide powder being disposed in the flame formed in the burner of the top-blown spray gun front end on vacuum deaerator plant, and described oxide powder is added to top blast on the liquid level of the molten steel in degassing vessel, the feature of the vacuum refining method of described molten steel is
Fuel and burning gas is made to form flame in the mode meeting following formula to described burner supply:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: gas feed speed is used in burning, and unit is Nm
3/ min
F: fuel feed speed, unit is Nm
3/ min
(G/F): oxygen fuel ratio, this oxygen fuel ratio=burning gas feed speed/fuel feed speed
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
2. the vacuum refining method of molten steel according to claim 1, is characterized in that,
Described oxide powder is Mn ore and/or CaO class sweetening agent.
3. the vacuum refining method of molten steel according to claim 1 and 2, is characterized in that,
From the nozzle of the centre hole front end that the axle core at described top-blown spray gun is arranged, Mn ore and/or CaO class sweetening agent and carrier gas are together sprayed, from burner supply fuel and the burning gas of the multiple holes around front ends be disposed in around described nozzle, and igniting forms flame, heats described oxide powder by this flame.
4. the vacuum refining method of molten steel according to claim 1 and 2, is characterized in that,
Supply more than any one in the geseous fuel of hydrocarbon class, the liquid fuel of hydrocarbon class and the solid fuel of carbon class and be used as described fuel.
5. the vacuum refining method of molten steel according to claim 3, is characterized in that,
Supply more than any one in the geseous fuel of hydrocarbon class, the liquid fuel of hydrocarbon class and the solid fuel of carbon class and be used as described fuel.
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| PCT/JP2013/056932 WO2013137292A1 (en) | 2012-03-15 | 2013-03-13 | Vacuum refining method of molten steel |
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| KR (1) | KR101529454B1 (en) |
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| JP6124022B2 (en) * | 2014-09-24 | 2017-05-10 | Ｊｆｅスチール株式会社 | Melting method of low carbon high manganese steel |
| JP6269550B2 (en) * | 2015-03-30 | 2018-01-31 | Ｊｆｅスチール株式会社 | Method for melting high manganese steel |
| RU2697113C1 (en) * | 2016-02-24 | 2019-08-12 | ДжФЕ СТИЛ КОРПОРЕЙШН | Refining method of molten steel in equipment for vacuum degassing |
| CN108220532A (en) * | 2016-12-13 | 2018-06-29 | 鞍钢股份有限公司 | A kind of double refining method for improving Cleanliness of Molten Steel |
| CN108611465A (en) * | 2016-12-13 | 2018-10-02 | 鞍钢股份有限公司 | A kind of molten steel refining method improving RH decarbonization rates |
| JP6648711B2 (en) * | 2017-02-07 | 2020-02-14 | Ｊｆｅスチール株式会社 | Hot metal desulfurization method |
| KR102359738B1 (en) * | 2018-04-17 | 2022-02-09 | 닛폰세이테츠 가부시키가이샤 | Molten Steel Manufacturing Method |
| JP6939733B2 (en) * | 2018-07-31 | 2021-09-22 | Ｊｆｅスチール株式会社 | Refining method of molten steel under reduced pressure |
| US20230142051A1 (en) * | 2020-04-01 | 2023-05-11 | Jfe Steel Corporation | Decarburization refining method for molten steel under reduced pressure |
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| WO2003004707A1 (en) * | 2001-07-02 | 2003-01-16 | Nippon Steel Corporation | Method for decarbonization refining of chromium-containing molten steel |
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| CN1164873A (en) * | 1995-08-28 | 1997-11-12 | 新日本制铁株式会社 | Process for vacuum refining of molten steel and apparatus therefor |
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| Publication number | Publication date |
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| JP5382275B1 (en) | 2014-01-08 |
| JPWO2013137292A1 (en) | 2015-08-03 |
| KR20140111710A (en) | 2014-09-19 |
| CN104169442A (en) | 2014-11-26 |
| KR101529454B1 (en) | 2015-06-16 |
| WO2013137292A1 (en) | 2013-09-19 |
| TWI490340B (en) | 2015-07-01 |
| TW201404889A (en) | 2014-02-01 |
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