CN104169442A - Vacuum refining method of molten steel - Google Patents
Vacuum refining method of molten steel Download PDFInfo
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- CN104169442A CN104169442A CN201380012488.3A CN201380012488A CN104169442A CN 104169442 A CN104169442 A CN 104169442A CN 201380012488 A CN201380012488 A CN 201380012488A CN 104169442 A CN104169442 A CN 104169442A
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- Prior art keywords
- molten steel
- fuel
- ore
- burner
- spray gun
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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
In a vacuum refining method of molten steel, an oxide powder is heated with a flame formed in a burner at the tip of a top-blowing lance arranged in a vacuum degassing device, and said oxide powder is added by spraying upwards onto the bath surface of the molten steel in the degassing tank. By supplying the fuel and combustion gas that satisfy the expression below to the aforementioned burner to form the flame, melt temperature decreases and Mn loss during addition of Mn ore are suppressed, decarburization treatment is efficiently performed, and a low-carbon, high-manganese steel is melted; or, melt temperature decreases during addition of a desulfurizing agent are suppressed, desulfurization treatment is efficiently performed, and a low-sulfur steel is melted. 0.4 <=(G/F)/(G/F)st <=1.1 (here, G: combustion gas supply rate (Nm3/min), F: fuel supply rate (Nm3/min), (G/F): oxygen combustion ratio (=combustion gas supply rate / fuel supply rate), (G/F)st: stoichiometric value of the oxy-fuel ratio of completely combusting fuel)
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 variation of the purposes of ferrous materials, it is many that situation about using under the environment than in the past harsher becomes.The consequent, also increases than in the past and becomes strict the requirement of mechanical characteristics of product etc.Under this situation, high strength, lighting, the cost degradation of works of take is object, exploitation has the low-carbon high-manganese steel (following, to be also denoted as " the high Mn steel of low C ") of the high strength of having concurrently and high working property, is widely used for the various fields such as pipeline steel or automotive sheet.At this, the high Mn steel of above-mentioned low C refers to C concentration below 0.05mass% and the steel of Mn concentration more than 0.5mass%.
In addition, in steel making working procedure, as for adjusting the cheap manganese source of the Mn concentration of molten steel, there are manganese ore (following, to be also denoted as " Mn ore ") or high carbon ferromanganese etc., when the high Mn steel of the above-mentioned low C of founding, carry out following operation: when molten iron being carried out to Decarburising and refining by converter, to dropping into Mn ore in converter, 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,, with reference to patent documentation 1) of regulation.
But, in the situation that use these cheap manganese sources, cannot in converter refining, reduce fully the C concentration in molten steel, or, because of the contained C of high carbon ferromanganese, cause the C concentration in the molten steel after tapping to rise.Consequently, in the situation that C concentration may exceed the allowed band of the high Mn steel of low C, need the processing that C is removed in enforcement from molten steel in addition.
As the method for removing expeditiously the C in molten steel, known have a method etc. of using RH vacuum degasser equal vacuum degassing equipment to carry out the method for vacuum decarburization to the molten steel of deoxidation state not and the oxygen sources (sending oxygen) such as molten steel winding-up oxygen being carried out decarburization under vacuum.In above-mentioned vacuum decarburization, as using high carbon ferromanganese to be used as the method in cheap manganese source, for example, in patent documentation 2, proposition has the Decarburising and refining initial stage at vacuum deaerator plant, high carbon ferromanganese is dropped into the method in molten steel, in addition, in patent documentation 3, proposing has when by Fruit storage stove founding ultra-low carbon steel, to until through the carbonization treatment time 20% during drop into high carbon ferromanganese method.But if add oxygen when the vacuum decarburization of the molten steel that contains a large amount of Mn is processed, oxygen not only also react and react with Mn with C in molten steel, so not only produce the oxidational losses of Mn and cause the decline of Mn yield, and be difficult to control accurately the Mn concentration in molten steel.
In addition, oxygen source and decarburization promotion method for using in the carbonization treatment of vacuum deaerator plant for example, propose to drop into the solid oxygen such as expanded skin in oriented vacuum tank in patent documentation 4, suppress thus the oxidation of Mn and preferentially carry out the method for decarburizing reaction; In C amount while proposing oriented converter blowing out in patent documentation 5 and the molten steel of temperature limited system, by vacuum degasser, add the method that Mn ore carries out decarburization; In patent documentation 6 and patent documentation 7, propose to have when by RH method, the steel after to converter tapping carries out carbonization treatment, by MnO powder or Mn ore powder and carrier gas one in the same way the surperficial top blast of molten steel in vacuum tank carry out the method for carbonization treatment; In addition, in patent documentation 8, propose to have via be arranged at nozzle on vacuum tank sidewall by Mn ore powder and carrier gas one in the same way the molten steel in the vacuum tank of RH vacuum degasser be blown into, by the oxygen in Mn ore, carry out the decarburization of molten steel, and improve the method for Mn concentration.
On the other hand, high additive value and use expansion along with ferrous materials are increasing improving the requirement of material behavior 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 to carry out in the stage in molten iron stage and molten steel, and at 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 to have various schemes in the past, for example to the molten steel in ladle, inject the method for sweetening agent, to molten steel, add the method that stirs after sweetening agent etc.But therefore, because these methods have been appended new operation between from converter tapping to Fruit storage, 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 there is desulfurizing function, merge, simplify secondary refining operation.For example, as using the sulfur method of vacuum deaerator plant to propose to have following method: with the RH vacuum degasser that possesses top-blown spray gun by sweetening agent and carrier gas the molten steel liquid level in together from top-blown spray gun to vacuum tank jet (projection), thus by liquid steel desulphurization (for example,, with reference to patent documentation 9).
But for example, the in the situation that of adding the oxide powders such as the solid oxygen such as Mn ore or sweetening agent in vacuum deaerator plant in carbonization treatment process, molten steel temperature declines because of the sensible heat of oxide powder or the required latent heat of thermolysis.The method declining for this molten steel temperature of compensation, thus exist in the front operation of vacuum outgas, improve the method for molten steel temperature, to the method etc. of adding metal A l in molten steel and improve by its combustion heat molten steel temperature.But, in front operation, improving in the method for molten steel temperature, the loss of the refractory materials in front operation is larger, causes cost to improve.In addition, add the method that metal A l heats up and exist the Al oxide compound because generating that the degree of cleaning of molten steel are declined, or the drawback such as auxiliary material cost rising.
Therefore, as the method while suppressing molten steel temperature and declining and to add solid oxygen, proposition has heats oxide powder to the method (for example,, with reference to patent documentation 10,11) projecting on molten steel liquid level while the flame of using the burner (burner) that is arranged on top-blown spray gun front end.In addition, as the method for adding sweetening agent, propose to have following method: from top-blown spray gun front end, oxygen and burning together sprayed with gas and sweetening agent and forms flame, by this flame, sweetening agent being heated and melting, and make it arrive molten steel liquid level (for example,, with reference to patent documentation 12).
Prior art document
Patent documentation
Patent documentation 1: Japanese kokai publication hei 04-088114 communique
Patent documentation 2: Japanese kokai publication hei 02-047215 communique
Patent documentation 3: Japanese kokai publication hei 01-301815 communique
Patent documentation 4: Japanese kokai publication sho 58-073715 communique
Patent documentation 5: Japanese kokai publication sho 63-293109 communique
Patent documentation 6: Japanese kokai publication hei 05-239534 communique
Patent documentation 7: Japanese kokai publication hei 05-239526 communique
Patent documentation 8: Japanese kokai publication hei 01-092312 communique
Patent documentation 9: Japanese kokai publication hei 05-311231 communique
Patent documentation 10: Japanese kokai publication sho 64-039314 communique
Patent documentation 11: Japanese kokai publication hei 07-041827 communique
Patent documentation 12: Japanese kokai publication hei 07-041826 communique
Summary of the invention
But the method that projects oxide powder in order to promote decarburization or denitrogenation, dehydrogenation is patent documentation 10 and 11 disclosed technology, the top condition when adding Mn ore as manganese source in vacuum deaerator plant is without any research.Similarly, the top condition that the method that sweetening agent is heated and added by the flame of burner is the disclosed technology of patent documentation 12 when adding sweetening agent in vacuum deaerator plant is without any research.
The present invention completes in view of the existing the problems referred to above point of prior art, its object is, a kind of casting method of low-carbon high-manganese steel is provided, in vacuum deaerator plant, when adding Mn ore as manganese source, can be while suppressing that molten steel temperature declines and Mn loses and carries out expeditiously carbonization treatment, and provide a kind of casting method of low-sulfur steel, similarly in vacuum deaerator plant, when interpolation sweetening agent carries out desulfurization processing, while can suppress molten steel temperature decline, carry out expeditiously desulfurization processing.
Contrivers etc. are in order to solve above-mentioned problem, pay close attention to C while carrying out carbonization treatment by vacuum deaerator plant and the reflex action of Mn and the variation behavior of molten steel temperature and further investigation repeatedly.Consequently, find that thereby following content develops the present invention: by Mn ore is suitably changed to the adding conditional of molten steel, can solve above-mentioned problem, specifically, by the combustion conditions that is arranged on the burner of top-blown spray gun front end is controlled to proper range, Mn ore is heated, reduction, and it is added to the molten steel top blast in vacuum tank, can not cause molten steel temperature to decline, can add Mn with high yield, and can enjoy decarburization facilitation effect, similarly, for sweetening agent, by the flame by being arranged at the burner of top-blown spray gun front end, heat, this sweetening agent of melting also adds it to the molten steel top blast in vacuum tank, can not cause molten steel temperature to decline and carry out desulfurization processing, in addition, preferably use the spray gun of appropriate structuring for this reason.
; the present invention is a kind of method of refining of molten steel; it heats oxide powder by the burner of top-blown spray gun front end or the flame of formation being provided 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; the vacuum refining method of above-mentioned molten steel is characterised in that, makes fuel and burning to meet the mode of following formula, to said burner, supply with to form flame with gas:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: gas feed speed (Nm for burning
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (gas feed speed/fuel feed speed for=burning)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
The vacuum refining method of molten steel of the present invention is characterised in that, above-mentioned oxide powder is Mn ore and/or CaO class sweetening agent.
In addition, the vacuum refining method of molten steel of the present invention is characterised in that, from the nozzle of the centre hole front end of the axle core setting at above-mentioned top-blown spray gun, Mn ore and/or CaO class sweetening agent and carrier gas are together sprayed, from being equipped on burner feed fuels and the burning gas of said nozzle a plurality of hole front ends around around, and igniting formation flame, by this flame, heat above-mentioned oxide powder.
In addition, the vacuum refining method of molten steel of the present invention is characterised in that, more than any in geseous fuel, the liquid fuel of hydrocarbon class and the solid fuel of carbon class of supply hydrocarbon class is used as above-mentioned fuel.
Invention effect
According to the present invention, except can suppress that molten steel temperature declines and with high Mn yield, implement Mn ore in vacuum deaerator plant to molten steel interpolation, can also improve decarbonization rate, therefore can be with high productivity and founding low-carbon high-manganese steel at low cost.In addition, according to the present invention, except suppressing molten steel temperature, decline and to implement sweetening agent in vacuum deaerator plant to the interpolation of molten steel, can also improve desulfuration efficiency, therefore founding low-sulfur steel expeditiously.
Accompanying drawing explanation
Fig. 1 is the signal vertical sectional view of RH vacuum degasser.
Fig. 2 is the figure of the structure of explanation top-blown spray gun used in the present invention.
Fig. 3 is the figure of structure of the top-blown spray gun of explanation prior art.
Fig. 4 means the chart of the relation of the C concentration before Fruit storage and the decarbonization rate (rimmed decarburization rate) that seethes with excitement.
Fig. 5 means the chart of the relation of C concentration before Fruit storage and Mn yield.
The chart of the combustion conditions that Fig. 6 means burner on the impact of Mn yield.
The chart of the combustion conditions that Fig. 7 means 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 Oxidation Number such as MnO.In the situation that using this Mn ore as manganese source and as adding to molten steel for promoting the oxygen source of decarburization, the different Mn oxide compound of 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)
Known according to above-mentioned (1)～(3) formula, the Oxidation Number of Mn oxide compound is higher, and in order to reduce, the needed C amount of Mn oxide compound is more.Therefore, in the situation that make the Mn oxide compound in Mn ore, be that the Mn oxide compound that Oxidation Number is low makes an addition in molten steel, the needed C amount of reduction reduction due to Mn ore, even so in the situation that the C concentration in molten steel is lower, also can expect to reduce fully Mn ore, and Mn yield is improved.
Therefore, invention personnel expect, from being equipped on top-blown spray gun vacuum deaerator plant when adding the Mn ore of powder in molten steel, control is arranged on the fuel combustion conditions (below also referred to as " combustion conditions of burner ") in the burner of above-mentioned top-blown spray gun front end, in heating Mn ore, the Mn Reduction of Oxide in Mn ore is added.
And, in order to confirm above-mentioned effect, in not using the laboratory experiment of molten steel, diversely change the combustion conditions of burner and the input method of Mn ore of top-blown spray gun front end, the preliminary experiment that carries out carrying out to ladle container top blast interpolation.
Specifically, in above-mentioned preliminary experiment, as top-blown spray gun, use multiple lance tube that the heating of Mn ore top blast are added, wherein this multiple lance tube can together spray the Mn ore of powder and carrier gas (Ar gas) from being arranged at the nozzle of the centre hole front end of axle core, and, can with gas, form flame from being equipped on burner ejection fuel and the burning of above-mentioned centre hole a plurality of hole front ends around around.Now, for above-mentioned fuel and burning with the feed speed of gas and have or not the heating of carrying out based on burner, mode with table 1 changes and adds, and investigated the variation of the composition of the different Mn oxide compound of Oxidation Number in the temperature variation of the Mn ore of top blast before and after adding and Mn ore.In addition, in above-mentioned preliminary experiment, Ar gas is used in carrier gas, and fuel is used propane gas, and burning is used pure oxygen with gas.
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 with gas
3/ min), the feed speed (Nm that F is fuel
3/ min), (G/F) be oxygen fuel ratio (burning is used the feed speed of gas with respect to the ratio of the feed speed of fuel), (G/F)
stthe stoichiometric number of the oxygen fuel ratio during for complete combustion of fuel.In addition, fuel is (G/F) in propane gas, the burning situation that is pure oxygen with gas
stbeing 5, that is, is 1Nm with respect to the feed speed F of fuel
3/ min, burning is 5Nm with the feed speed G of gas
3/ min.
Known according to above-mentioned table 1, when Mn ore and carrier gas are together added, can't help under the condition of the No.1 that the flame of burner of spray gun front end heats, in Mn ore before and after dropping into, do not find any variation, but under the condition of No.2～7 of the heating of Mn ore being added at the flame by burner, the temperature of Mn ore rises, then has, in above-mentioned No.2～7, (G/F) in the combustion conditions of burner/(G/F)
stin No.4～7 in 0.4～1.1 scope, 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, sex change is the Mn oxide compound that Oxidation Number is low, still, makes (G/F)/(G/F)
stbe reduced in 0.3 No.8, because flame self does not generate, therefore identical with the condition of No.1, in the Mn ore before and after adding, find to change.
Known according to the above results, in the situation that the combustion conditions that is formed at the burner of spray gun leading section is controlled to proper range, , in the situation that the combustion conditions of burner is controlled to hypoxgia side but not oxygen excess side, the flame forming is reductibility, promote the reduction of the Mn oxide compound in Mn ore, therefore, even if the C in molten steel measures when less, Mn ore is also reduced fully, thereby Mn yield improves, in addition, in the situation that Mn ore is heated by the flame of burner, by the temperature of Mn ore, rise to suppress the decline of molten steel temperature, have again, by adding Mn, utilize the oxygen in Mn ore to promote decarburizing reaction.And known, in the situation that adding sweetening agent, spray gun front end also can expect effect same as described above.
The present invention is based on above-mentioned new technological thought and viewpoint and develop.
Next, the vacuum deaerator plant vacuum refinement of molten steel of the present invention being used describes.
For the vacuum deaerator plant that can be used in molten steel vacuum refining of the present invention, there are RH vacuum degasser and DH vacuum degasser, VOD stove etc., wherein the most representative is RH vacuum degasser.Therefore, take RH vacuum degasser describes as example.
Fig. 1 is the vertical sectional view of typical RH vacuum deaerator plant.
This RH vacuum deaerator plant comprises the ladle 2 of taking in molten steel 1 and the degassed portion 3 that molten steel is carried out to Fruit storage (being designated hereinafter simply as " degassed processing ").Above-mentioned degassed portion 3 comprises the vacuum tank 4 and the not shown exhaust equipment being connected with vacuum tank 4 that molten steel is imported to inside and carries out degassed processing.In the upper side of vacuum tank 4, be provided with the venting port 7 being connected with exhaust equipment and the input port (chute) 8 of adding the auxiliary materials such as alloy raw material (composition adjusting agent) or solvent.
In addition, be equipped with two immersion tubes 5 and 6 in the bottom of vacuum tank 4, be connected with pipe arrangement 10 therein on a side immersion tube (being 5 in Fig. 1), this pipe arrangement 10 is blown into for making molten steel 1 form the recycle stream of circulation in immersion tube.And, when carrying out degassed processing, above-mentioned two immersion tubes are immersed in the molten steel in ladle, by not shown exhaust equipment to carrying out exhaust in vacuum tank 4, when the molten steel in ladle 21 is imported in vacuum tank 4, via above-mentioned pipe arrangement 10, to the interior supply recycle stream of immersion tube 5 rare gas elementes such as () Ar gas, make the interior generation bubble of immersion tube 5 and make bubble increase.Thus, the molten steel in immersion tube 5 also together rises with recycle stream and flow in vacuum outgas groove, after degassed processing, forms the circulation that immersion tube (being 6 in Fig. 1) through the opposing party declines and returns to the molten steel in ladle, carries out thus degassed processing.
Have again, the top of vacuum tank 4 with from above the form inserted in vacuum tank 4 be equipped with top-blown spray gun 9.This top-blown spray gun 9 is multiple lance tubes, and it is equipped with: the passage of the oxide powders such as oxygen and Mn ore or CaO class sweetening agent and their carrier gas of conveyance; At this passage front end, above-mentioned substance is sprayed and the nozzle to the surface winding-up of molten steel by them; Fuel and for the burning that makes this fuel combustion the passage with gas; And make above-mentioned fuel combustion and form the burner of flame at this passage front end.
In addition, above-mentioned top-blown spray gun 9 links with the not shown hopper (hopper) that stores auxiliary material, together supplies with oxide powder and the carrier gas such as Mn ore or CaO class sweetening agent.As above-mentioned CaO class sweetening agent, mainly use at unslaked lime (CaO) or Wingdale (CaCO
3), slaked lime (Ca (OH)
2), mix the fluorite (CaF of 5～30mass% left and right in rhombspar (CaO-MgO) etc.
2) or aluminum oxide (Al
2o
3) etc. the material that forms of CaO scorification promotor.In addition, the rare gas elementes such as Ar gas or nitrogen are used in above-mentioned carrier gas conventionally.
In addition, above-mentioned top-blown spray gun 9 links with gas supply pipe with not shown fuel feed pipe and burning, as above-mentioned fuel, at least one in the carbon class solid fuels such as liquid fuel, coke or coal of the hydrocarbon classes such as geseous fuel, diesel oil or kerosene of the hydrocarbon classes such as supplying propane gas or Sweet natural gas, in addition, as burning gas, the oxygen-containing gas of oxygen gas-supplying, rich oxidation air, air etc.Have, above-mentioned top-blown spray gun 9 carries out water-cooled again, therefore also with for supplying with/discharge the not shown water coolant supplying drainage of water-cooled water coolant used links.
At this, the top-blown spray gun that the vacuum refinement of molten steel of the present invention is used describes.
Fig. 2 means the figure of an example of the preferred top-blown spray gun that the present invention is used, (a) is vertical sectional view, is (b) upward view.This top-blown spray gun comprises: passage (being designated hereinafter simply as " oxygen channel " or " powder, carrier gas passage ") 11, and it doubles as supplies with to the oxygen channel of oxygen of molten steel winding-up and oxide powder, the carrier gas passage of the carrier gas of supply oxide powder and oxide powder; Internal water cooling cylindrical shell 13, " centre hole " that it forms at the axle center part nozzle 12 that to possess by the front end that is arranged on this passage 11 be spray gun front end; Outside water-cooled cylindrical shell 14, it surrounds this internal water cooling cylindrical shell 13 around; And many " hole around ", it is included in feed fuels between above-mentioned internal water cooling cylindrical shell 13 and outside water-cooled cylindrical shell 14 or burning with the passage 15 of gas and is arranged on the burner 16 that this passage front end is spray gun front end.Above-mentioned hole is around dual pipe structure, and fuel is in inner tube side flow, and burning uses gas in outer tube side flow, but also can change the passage and the passage of burning with gas of fuel.
And, from the oxide powder of nozzle 12 ejections of the front end of above-mentioned powder, carrier gas passage 11 etc., by the flame forming in the burner 16 at spray gun front end, be heated, or be heated, reduce, or be heated, melting, and to the molten steel liquid level winding-up in vacuum tank.
In addition, in Fig. 2, by 8, around in hole is with acting on the pilot burner (pilot burner) 17 of the fuel ignition of ejection, so burner radical is 7.Yet, the fuel of supplying with gas passage from the burning of burner 16 and gas burning for (oxidizing gas) supplied with gas passage from burning because jet hole separately approach (repetition) thus moment mixing, within the scope of combustion limits, but because the envrionment temperature in vacuum tank is high, so also take fire even without portfire, below top-blown spray gun 9, form flame.Therefore, conventionally do not need pilot burner, but can arrange yet.
At this, the centre hole of above-mentioned top-blown spray gun front end and the around position relationship in hole are that nozzle 12 is adjusted and come also to have no relations with the position relationship of burner 16, but because of the heated oxide thing powder expeditiously of the words for the jet flow that contains oxide powder around being encased by the flame of burner, so preferably as illustrated in fig. 2, axle core at spray gun sets nozzle, and sets burner around at it.
In addition, the shape of nozzle 12 that is arranged at the centre hole front end of top-blown spray gun in Fig. 2 is by the part of reduced cross-sectional and these two Laval-cavity nozzles that cone forms of the part of enlargement in section, but can be also the nozzle of rectilinear form.In addition, two cones position that be connected, that cross section is the narrowest that dwindles part and expansion section s in Laval-cavity nozzle, is commonly called aditus laryngis.
Therefore the top-blown spray gun of the Fig. 2 consisting of this structure possesses oxygen channel, powder, carrier gas passage, fuel channel and burning gas passage, can carry out the preheating of vacuum tank, the heating of dirt settling in the heating (intensifications) of the molten steel in vacuum tank and vacuum tank, remove and all processing such as powder of jetting to molten steel.
In addition, above-mentioned top-blown spray gun 9 used in the present invention is not limited to the scope of above-mentioned explanation, for example, also can set in the surrounding of top-blown spray gun a plurality of burners and use these burners by the Mn ore heating being blown into from top-blown spray gun.Have again, can also separately be provided for top-blown spray gun and burner that Mn ore adds.
Next, to using the casting method of low-carbon high-manganese steel of the RH vacuum degasser of above-mentioned explanation to describe.
First, by the molten iron from blast furnace casting, after being loaded into the maintenance containers such as molten iron boiler or torpedo car (torpedo car) or conveyance container, conveyance is to the steel operation processed of carrying out Decarburising and refining.Conventionally, the situation of molten iron being implemented the molten iron preliminary treatment such as desulfurization or dephosphorization in this conveyance way is more, in the present invention, even the in the situation that of not needing molten iron preliminary treatment at ingredient standard aspect, also preferably implements molten iron preliminary treatment.Be so why because, in converter, as manganese source, add Mn ore, do not carrying out molten iron preliminary treatment particularly do not carry out dephosphorization treatment in the situation that, during blowing in converter, need to side by side carry out dephosphorization with decarburization, owing to adding in a large number CaO class fusing assistant for this reason, so that the slag amount of converter increases, the manganese amount being assigned in slag increases and causes Mn yield to decline.
In ensuing steel operation processed, molten iron is being packed into after converter, as manganese source, add Mn ore, also add as required a small amount of unslaked lime equal solvent, top blast and/or BOTTOM OXYGEN are carried out decarburization blowing, make the molten steel that predetermined component forms, then, the state that maintains not deoxidation directly keeps container tapping to molten steel such as ladles.The alloy iron that now, also can add the cheapnesss such as high carbon ferromanganese of specified amount is manganese source.
In addition, due in above-mentioned steel operation processed, use the manganese source that Mn ore or high carbon ferromanganese etc. are cheap, thus 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 is also preferably suppressed at below 0.2mass%.If C concentration surpasses 0.2mass%, the carbonization treatment time in the vacuum deaerator plant of subsequent handling is elongated, not only productivity declines, and in order to compensate the reduction of the molten steel temperature causing along with the prolongation of carbonization treatment time, produce the needs that improve tapping temperature, cause the decline of iron yield, the refractory materials cost causing because of the increase of refractory wear amount to rise, therefore not preferred.
Next, from the steel of converter tapping to RH vacuum degasser or DH vacuum degasser, the conveyance of VOD stove equal vacuum degassing equipment, implement the degassed processing such as carbonization treatment.Below, to using the casting method of the low-carbon high-manganese steel of the RH vacuum degasser shown in Fig. 1 to describe.
In the RH vacuum degasser shown in Fig. 1, the molten steel 1 of deoxidation state is not carried out to vacuum decarburization processing in the time of (also this processing being called below to " (rimming treatment) processed in boiling "), in this boiling is processed, from top-blown spray gun 9 top blast, add Mn ore.Now, above-mentioned Mn ore need to heat at the flame by being formed at the burner of top-blown spray gun 9 leading sections, reduce and add to the liquid level winding-up of molten steel.Specifically, via the fuel channel that is arranged at the surrounding hole on top-blown spray gun 9, this fuel ejection is supplied with and made to fuel to the burner 16 of spray gun front end, via burning, with gas passage, gas ejection for this burning is supplied with and made to burning with gas to the burner 16 of spray gun front end, by igniting, in burner, form flame.And, the nozzle 12 ejection Mn ores via the powder of medium pore, carrier gas passage 11 from spray gun front end, flame heating, reduction top blast by the Mn ore of ejection by said burner add.In addition, preferably, when starting to add Mn ore, in burner, form in advance flame.
At this, for the flame forming in the burner of spray gun front end in order to heat, reduce above-mentioned Mn ore, fuel and burning need to meet following formula with gas:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: gas feed speed (Nm for burning
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (gas feed speed/fuel feed speed for=burning)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
As mentioned above, if (G/F)/(G/F)
stsurpass 1.1, 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, because flame self can not form, so also cannot heat Mn ore.Preferably (G/F)/(G/F)
stmore than 0.4 and in lower than 1.0 scope.
By heating like this and add Mn ore, can suppress molten steel temperature that the interpolation along with Mn ore causes decline (temperature loss).In addition, because be satisfied the Mn ore of the flame heating of above-mentioned combustion conditions, be reduced and add in molten steel, so promote the reduction reaction of Mn ore, Mn yield improves, and therefore can reduce the addition of Mn alloy.Have again, because the oxygen in Mn ore plays a role as solid oxygen, promote decarburizing reaction, so the interpolation of Mn ore can be shortened the boiling treatment time, boost productivity.
In addition, in above-mentioned boiling is processed, can be also, after heating and add Mn ore, via the nozzle 12 ejection oxygen of oxygen channel 11 and front end thereof, and to molten steel winding-up, to promote thus decarburization or heating molten steel.In addition, when above-mentioned carbonization treatment or hyperthermic treatment, because do not use burner, so preferably at fuel channel and the rare gas elementes such as nitrogen or Ar gas that circulate in gas passage for burning, prevent the obturation of the burner that causes because splashing etc.
When carrying out the above-mentioned boiling processing of specified time, C concentration in molten steel reaches after the prescribed value below ingredient standard value, adds the strong reductors such as Al reduce the oxyty (deoxidation) molten steel from raw material input port 8 to molten steel 1, finishes boiling and processes.In addition, in the situation that the molten steel temperature of boiling processing after finishing is lower than such as desired temperature of subsequent handling such as continuous casting operations, also can further from raw material input port, to molten steel, add Al, and the winding-up of the surface from above-mentioned top-blown spray gun to molten steel oxygen (sending oxygen), make Al burning, make thus molten steel temperature increase.
Add reductor and molten steel 1 after deoxidation in several minutes thereafter, proceed the circulation (this processing being called to " calm processing ") of molten steel, and as required, from raw material input port 8, to composition adjusting agents (alloying constituent) such as molten steel 1 input Al, Si, Mn, Ni, Cr, Cu, Nb, Ti, molten steel component is adjusted to the compositing range of regulation, afterwards, make vacuum tank 4 return to normal atmosphere, finish degassed processing.
Next, to using the casting method of low-sulfur steel of the RH vacuum degasser of above-mentioned explanation to describe.In addition, molten iron from blast furnace casting, through bessemerize, tap and conveyance identical with the casting method of above-mentioned low-carbon high-manganese steel to the process of RH vacuum degasser, so description thereof is omitted.
For conveyance to RH vacuum degasser in the molten steel of deoxidation state not, carry out as required the specified time, via the oxygen channel 11 of top-blown spray gun 9 with and the boiling from decarburization to molten steel winding-up oxygen that carry out of the nozzle 12 of front end process, C concentration in molten steel reaches after the prescribed value below ingredient standard value, from raw material input port 8, to molten steel 1, add the strong reductors such as Al and reduce the oxyty (deoxidation) molten steel, finish boiling and process.
In addition, in the situation that boiling processing finish after, be molten steel temperature after deoxidation lower than such as desired temperature of subsequent handling such as continuous casting operations, also can further from raw material input port, to molten steel, add Al, and the winding-up of the surface from above-mentioned top-blown spray gun to molten steel oxygen (sending oxygen), make Al burning, make thus molten steel temperature increase.In addition, can be also, with the casting method of above-mentioned low-carbon high-manganese steel similarly, when the molten steel 1 of deoxidation state not being seethed with excitement processing, from top-blown spray gun 9 top blast, add Mn ores.
Next, in the time of molten steel winding-up CaO class sweetening agent from from top-blown spray gun 9 to above-mentioned deoxidation, by the flame forming in burner 16, heat this CaO class sweetening agent and make its melting, and to winding-up interpolation on the liquid level of molten steel, carrying out desulfurization processing.Specifically, via the fuel channel that is arranged at the surrounding hole on top-blown spray gun 9 to burner 16 feed fuels of spray gun front end and make this fuel ejection, via burning, with gas passage, to the burner 16 of spray gun front end, supply with burning with gas and this burning is sprayed with gas, and form flame by igniting, simultaneously, powder, carrier gas passage 11 via medium pore spray CaO class sweetening agents from the nozzle 12 of spray gun front end, and the CaO class sweetening agent of this ejection is added by flame heating, melting the top blast of said burner.In addition, preferably, when starting to add CaO class sweetening agent, in burner, form in advance flame.
At this, in order to heat, the above-mentioned sweetening agent of melting and the flame that forms in the burner of spray gun front end, fuel and burning need to meet following formula with gas:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: gas feed speed (Nm for burning
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (gas feed speed/fuel feed speed for=burning)
(G/F)
st: the stoichiometric number of oxygen fuel ratio during complete combustion of fuel.
This be because, if (G/F)/(G/F)
stsurpass 1.1, the oxidisability grow of flame, although sweetening agent is heated, not carrying out reduction reaction is desulphurization reaction.On the other hand, if (G/F)/(G/F)
stlower than 0.4, because flame self can not form, therefore also cannot heat sweetening agent.Preferably (G/F)/(G/F)
stmore than 0.4 and lower than 1.0 scope.
By heating like this and add sweetening agent, the temperature of the molten steel that can suppress to cause along with the interpolation of sweetening agent decline (temperature loss).In addition, owing to meeting the flame of above-mentioned combustion conditions, can not form peroxidation environment, therefore can promote that reduction reaction is desulphurization reaction, improve desulfurization degree.
In addition, in the situation that do not need the carbonization treatment in RH vacuum degasser aspect ingredient standard, also can be when molten steel be tapped from converter to ladle, to adding metal A l in the molten steel stream in tapping, make steel liquid deoxidation.Now, except Al, the fusing assistant that adds lime or contain lime in can also flowing to tapping.For the molten steel of tapping to ladle, after to the slag on molten steel, add the slag properties-correcting agent such as Al, implement the slag modification of the Mn oxide reduction such as the ferriferous oxides such as the FeO in slag or MnO, then conveyance is to RH vacuum degasser.
For adding above-mentioned reductor, carry out the molten steel 1 after deoxidation, after the calmness implementing to make molten steel circulation and carry out degassed processing by RH vacuum degasser process, then from raw material input port 8, to composition adjusting agents (alloying constituent) such as molten steel 1 input Al, Si, Mn, Ni, Cr, Cu, Nb, Ti, molten steel component is adjusted to as required to the compositing range of regulation, make afterwards vacuum tank 4 return to normal atmosphere, finish degassed processing.
In addition, although the low-carbon high-manganese steel of use RH vacuum degasser and the casting method of low-sulfur steel are illustrated in above-mentioned explanation, even but in the situation that using other vacuum deaerator plants such as DH vacuum degasser or VOD stove, also founding low-carbon high-manganese steel and low-sulfur steel according to the method described above.
Embodiment 1
At the molten iron to from blast furnace casting, carry out the molten iron preliminary treatment of dephosphorization, desulfurization, by 350 tons of converters, blown, make and there is composition and consist of C:0.03～0.09mass%, below Si:0.05mass%, Mn:0.1～0.85mass%, below P:0.03mass%, the steel 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 directly tapped to ladle under the state of not deoxidation, and conveyance is to the RH vacuum degasser that possesses top-blown spray gun, under deoxidation state, directly do not implementing degassed processing, wherein this degassed processing is accompanied by the boiling processing of carrying out vacuum decarburization processing.While in addition, arriving RH vacuum degasser in molten steel O concentration in the scope of 0.03～0.07mass%.
In above-mentioned boiling is processed, making the flow of recycle stream (Ar gas) is 1500NL/min, the vacuum tightness that makes to arrive vacuum tank is 6.7～40kPa (fixing under each condition), and makes the combustion conditions (((G/F)/(G/F) of the burner of the kind of used top-blown spray gun, the interpolation that has or not Mn ore and addition means, spray gun front end
st)) and have or not and give oxygen to change as shown in table 2ly.
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 is processed is C:0.002～0.003mass%, and Mn:0.5～1.2mass%, the in the situation that Mn concentration being too low after boiling processing finishes, adding manganese metal and carries out the adjustment of Mn concentration.
In addition, when boiling is processed hypoxgia in the situation that, on one side surface winding-up oxygen (sending oxygen) from from the nozzle of top-blown spray gun front end to molten steel carry out decarburization on one side.
In addition, as the top-blown spray gun of above-mentioned RH vacuum degasser, use to be applicable to the spray gun shown in Fig. 2 of the present invention and with these two kinds of the spray guns shown in the similar Fig. 3 of the disclosed spray gun of patent documentation 10.The spray gun of Fig. 3 is provided with and the fuel gas supply hole 24 of burning and being connected with gas passage 23 on the expansion mouth 22 being connected with aditus laryngis 21, wherein aditus laryngis 21 is connected with the oxygen channel 20 that is arranged at the axle core of spray gun, have, this spray gun is the structure from the squit hole 26 ejection Mn ores of powder, carrier gas passage 25 front ends again.
And, in the situation that use the spray gun shown in Fig. 2, the interpolation of Mn ore by via centre hole, be powder, carrier gas passage 11 and nozzle 12 and by Mn ore and carrier gas (Ar gas) in the same way the surperficial top blast of molten steel carry out.In addition, in the situation that form flame in the burner of top-blown spray gun front end, as fuel, make LNG with 240Nm
3/ hr supplies with, and makes pure oxygen at 120～600Nm in addition as burning with gas
3in the scope of/hr, change and supply with, thereby making the combustion conditions ((G/F)/(G/F) of burner
st) change.In addition (G/F) in this situation,
stbe that 2 (the feed speed F with respect to fuel is 1Nm
3the situation of/min, burning is 2Nm with the feed speed G of gas
3/ min).In addition, the formation time of flame is all 10min (fixing) under any condition.
On the other hand, in the situation that use the spray gun shown in Fig. 3, by on one side via oxygen channel 20 ejections gases (oxygen) for burning, on one side via powder, carrier gas passage 25 by Mn ore and carrier gas (Ar gas) top blast on molten steel liquid level in the same way, carry out the interpolation of Mn ore.In addition, in the situation that the front end of top-blown spray gun forms flame, as fuel, make LNG with 240Nm
3/ hr supplies with, and as burning, with gas, makes pure oxygen with 470Nm
3/ hr supplies with.In addition, the formation time of flame is 10min.
Table 2
Decarbonization rate when Mn yield, the boiling in the Mn ore that after molten steel component (C, Mn), the boiling of having recorded in the lump before degassed processing (boiling process before) in table 2 processed, Mn concentration, the boiling of (still, based on add concentration that manganese metal carries out adjusts before) added in processing processed and the boiling molten steel temperature before and after processing is poor.In addition the decarbonization rate that, above-mentioned table 2 is recorded is to start till the average decarbonization rate that the decarburized amount that the processing of seethe with excitement finishes obtains divided by seething with excitement the treatment time when arriving RH.In addition, molten steel temperature is poor to rise for positive situation means molten steel temperature, for negative situation means molten steel temperature, declines.
According to the known following content of table 2.
First, No.16～18th, the top-blown spray gun of use Fig. 2, forms flame at spray gun front end when boiling is processed, and does not add the comparative example of Mn ore, though molten steel temperature rising, decarbonization rate is 0.0033～0.0036mass%/min.On the other hand, the decarbonization rate having added in No.1～15 of Mn ore is 0.0040～0.0052mass%/min, known by the interpolation of Mn ore, has promoted decarburization.Think that this is because the Mn oxide compound in Mn ore plays the effect of solid oxygen effectively, has promoted the decarburizing reaction of molten steel.In addition, in the comparative example of these No.16～18, the needed hypoxgia of decarburization, has to send oxygen, therefore produces Mn loss.
Next, to adding the example of Mn ore, analyze.
No.13～15th, the top-blown spray gun of use Fig. 2, from auxiliary material input port, (Fig. 1 8) do not add heatedly the comparative example of Mn ore in vacuum tank, due to sensible heat or decomposition heat (latent heat) caused temperature loss of following Mn ore to add, molten steel temperature declines more than 30 ℃, decarbonization rate is only 0.004mass%/min level, and Mn yield is only in 40～50% levels.
In addition, No.10～12nd, use the top-blown spray gun shown in Fig. 2 but without the flame heating Mn ore of burner carry out the comparative example of top blast interpolation, with above-mentioned No.13～15 similarly, owing to following sensible heat or the latent heat that Mn ore adds that molten steel temperature is declined to a great extent, Mn yield also with above-mentioned No.13～15 step-down similarly.
On the other hand, No.19 is the top-blown spray gun that uses the prior art shown in Fig. 3, the example of the heating of Mn ore being added by the flame forming at spray gun front end.In this example, molten steel temperature rises more than 10 ℃.Think that this is because by the heating of Mn ore is added, can reduce temperature loss, thereby thermo-efficiency is improved.In addition, Mn yield is also increased to and approaches 80%.Think that this is because by the flame heating Mn ore by reductibility, Mn ore reduction is added.
Have again, No.1～6th, is used the top-blown spray gun shown in Fig. 2, the example that Mn ore is added while the flame heating top blast of using burner, molten steel temperature after boiling is processed rises more than 9 ℃, 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 generation reason of this difference is as follows, the top-blown spray gun of the Fig. 3 using in No.19 mixes Mn ore and burning spray with gas at spray gun front end, with respect to this, the top-blown spray gun of the Fig. 2 using in No.4 is from the nozzle ejection Mn ore of spray gun front end, and utilize the flame be provided in nozzle burner around to encase this jet flow and by the heating of Mn ore, so the spray gun of Fig. 2 can heat, reduce Mn ore expeditiously.
On the other hand, No.7 is except the combustion conditions of burner ((G/F)/(G/F)
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 and No.13～15 are similarly lower.
On the contrary, No.8, the 9th, 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, because the oxygen deficiency of supplying with can not form flame, thereby Mn ore is not heated, therefore, owing to following sensible heat or the caused temperature loss of latent heat of the interpolation of Mn ore that molten steel temperature is declined, Mn yield is also lower in the same manner with No.13～15.
At this, Fig. 4 represent in the example of No.1～6 and the comparative example of No.7～15, the C concentration and the relation of decarbonization rate of RH before processing, Fig. 5 represents C concentration in the example of above-mentioned No.1～6 and the comparative example of No.7～15, before RH processing and the relation of Mn yield.Known according to these two figure, the C concentration before RH processes is at par in the situation that, and the decarbonization rate of example is higher than comparative example, and Mn yield improves.Think that this is because as mentioned above, in the situation that the heating of Mn ore top blast are added by the flame of best combustion condition, because Mn ore arrives the reduction of carrying out Mn oxide compound before molten steel, so the required C quantitative change of the reduction of Mn ore is few.Consequently, even in the situation that the C concentration of RH before processing is lower, also can reduce fully Mn ore, the oxygen in Mn ore can work fully as solid oxygen.That is, think in comparative example, in the situation that the C concentration of RH before processing is lower, for reducing, the C of Mn ore is not enough, and Mn yield declines.
In addition, Fig. 6 represent in the example of No.1～6 that the flame by burner heats Mn ore add and the comparative example of No.7～9, ((G/F)/(G/F)
st) with the relation of Mn yield.Known according to this figure, ((G/F)/(G/F)
stin the time of in 0.4～1.1 scope, Mn yield reaches more than 80%, wherein at ((G/F)/(G/F)
stbe that more than 0.4 and lower than in 1.0 scope time, Mn yield can reach more than 90% high value.
According to above result, by using, be applicable to spray gun of the present invention and in the burner of spray gun front end, form flame to be applicable to condition of the present invention, and with this, heating of Mn ore, reduction top blast are added, not only can suppress molten steel temperature decline, with high yield, add Mn, can also improve decarbonization rate, therefore can high-level efficiency and implement at low cost the founding of low-carbon high-manganese steel.
Embodiment 2
Molten iron from blast furnace casting is carried out the molten iron preliminary treatment of dephosphorization, desulfurization, by 350 tons of converters, blown, make and there is composition and consist of C:0.03～0.09mass%, below Si:0.05mass%, Mn:0.1～0.85mass%, below P:0.03mass%, the steel of S:0.0037～0.0042mass%.
Molten steel after bessemerizing is directly tapped to ladle under the state of not deoxidation, and conveyance is to the RH vacuum degasser that possesses top-blown spray gun, under deoxidation state, directly do not implement degassed processing, wherein in this degassed processing, following the boiling of carrying out vacuum decarburization processing to process.While arriving RH vacuum degasser in molten steel O concentration in the scope of 0.03～0.07mass%.
In above-mentioned boiling is processed, making the flow of recycle stream (Ar gas) is 1500NL/min, the vacuum tightness that makes to arrive vacuum tank is 6.7～40kPa (fixing under each condition), on one side from the nozzle of top-blown spray gun front end, oxygen is sent to the oxygen processing of seething with excitement on one side to the surface of molten steel, C concentration in molten steel reaches after the prescribed value below ingredient standard value, to molten steel, add Al and carry out deoxidation, finish boiling and process., to above-mentioned molten steel add CaO class sweetening agent, implement desulfurization and process thereafter.In addition, above-mentioned sweetening agent use granularity is the CaO-Al 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 combustion conditions of the adding conditional of sweetening agent (have or not burner heating), burner (((G/F)/(G/F)
st)) change as shown in table 3ly.In addition, about sweetening agent, using the top-blown spray gun shown in Fig. 2 is powder, carrier gas passage 11 and nozzle 12 via centre hole, by sweetening agent and carrier gas (Ar gas) molten steel surface winding-up interpolation in the same way.
In addition, in the situation that form flame in the burner of top-blown spray gun front end, with 240Nm
3/ hr supplies with the LNG as fuel, and makes to use the pure oxygen of gas at 120～600Nm as burning
3in the scope of/hr, change ground and supply with, make thus the combustion conditions ((G/F)/(G/F) of burner
st) change.In addition (G/F) in this situation,
stbe that 2 (the feed speed F with respect to fuel is 1Nm
3the situation of/min, burning is 2Nm with the feed speed G of gas
3/ min).
Table 3
The molten steel temperature of having recorded in the lump in table 3 before and after the S concentration in the molten steel before and after degassed process and the desulfurization degree of trying to achieve according to its value, sweetening agent projection is poor.In addition, molten steel temperature is poor to rise for positive situation represents molten steel temperature, for negative situation represents molten steel temperature, declines.
According to the known following content of table 3.
No.9 is used 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, because the sensible heat of following sweetening agent to add declines to a great extent molten steel temperature, desulfurization degree is low 60% level that reaches also.
On the other hand, No.1～6th, is used the top-blown spray gun shown in Fig. 2 and sweetening agent is carried out to the example of top blast interpolation heatedly by the flame of burner, almost not because sweetening agent adds the temperature loss causing.Think that this is because by sweetening agent is heated and added, temperature loss is reduced, and thermo-efficiency is improved.In addition, desulfurization degree also can reach more than 78%.Think that this is because the flame of burner is reductibility, thereby can promote the desulphurization reaction of molten steel.
On the other hand, No.7 is except the combustion conditions of burner ((G/F)/(G/F)
st) higher than beyond scope of the present invention, the comparative example identical with the example of No.1～6, although molten steel temperature rising, low 60% level that reaches of desulfurization degree.Think this be because, because flame is not reductibility, so fail to carry out the desulphurization reaction that reduction reaction is molten steel.
On the contrary, No.8 is combustion conditions except burner ((G/F)/(G/F)
st) lower than beyond scope of the present invention, the comparative example identical with the example of No.1～6, because the oxygen deficiency of supplying with can not form flame, sweetening agent is not heated, and therefore because temperature loss makes molten steel temperature, declines to a great extent.But, owing to supplying with sweetening agent with unburned reducing gas, so desulfurization degree is up to 88.1%.
At this, Fig. 7 represent in the flame heating sweetening agent of burner example that add, No.1～6 and No.7,8 comparative example, ((G/F)/(G/F)
st) with the relation of desulfurization degree.Known according to this figure, ((G/F)/(G/F)
st1.1, when following, desulfurization degree reaches more than 78%, wherein at ((G/F)/(G/F)
stbe that more than 0.4 and lower than in 1.0 scope time, desulfurization degree can reach the high value of 90% front and back.In addition, although even (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 declines to a great extent, so not preferred.
According to above result, by using, be applicable to spray gun of the present invention and in the burner of spray gun front end, form flame to be applicable to condition of the present invention, and with this, sweetening agent heating, melting top blast are added, can suppress the decline of molten steel temperature, and can improve desulfurization degree, therefore can implement expeditiously the founding of low-sulfur steel.
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 hole
25: powder, carrier gas passage
26: powder, carrier gas squit hole
Claims (4)
1. the vacuum refining method of a molten steel, the flame forming in its burner by the top-blown spray gun front end on being provided in vacuum deaerator plant heats oxide powder, and described oxide powder is added to top blast on the liquid level of the molten steel in degassing vessel, the vacuum refining method of described molten steel is characterised in that
Make fuel and burning to meet the mode of following formula, to described burner, supply with to form flame with gas:
0.4≤(G/F)/(G/F)
st≤1.1
At this, G: gas feed speed (Nm for burning
3/ min)
F: fuel feed speed (Nm
3/ min)
(G/F): oxygen fuel ratio (gas feed speed/fuel feed speed for=burning)
(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 of the axle core setting at described top-blown spray gun, Mn ore and/or CaO class sweetening agent and carrier gas are together sprayed, from being equipped on burner feed fuels and the burning gas of described nozzle a plurality of hole front ends around around, and igniting formation flame, by this flame, heat described oxide powder.
4. according to the vacuum refining method of the molten steel described in any one in claim 1～3, it is characterized in that,
More than any in geseous fuel, the liquid fuel of hydrocarbon class and the solid fuel of carbon class of supply hydrocarbon class be used as described fuel.
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| JP2012058102 | 2012-03-15 | ||
| JP2012-058102 | 2012-03-15 | ||
| PCT/JP2013/056932 WO2013137292A1 (en) | 2012-03-15 | 2013-03-13 | Vacuum refining method of molten steel |
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| CN104169442B CN104169442B (en) | 2015-12-30 |
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| KR (1) | KR101529454B1 (en) |
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| 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 |
| CN108699614A (en) * | 2016-02-24 | 2018-10-23 | 杰富意钢铁株式会社 | The method of refining of molten steel in vacuum deaerator plant |
| TWI698532B (en) * | 2018-04-17 | 2020-07-11 | 日商日本製鐵股份有限公司 | Method for manufacturing molten steel |
| CN115335537A (en) * | 2020-04-01 | 2022-11-11 | 杰富意钢铁株式会社 | Decarburization refining method of molten steel under reduced pressure |
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| JP6028750B2 (en) * | 2014-02-21 | 2016-11-16 | Ｊｆｅスチール株式会社 | Method for melting manganese-containing low carbon steel |
| 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 |
| JP6648711B2 (en) * | 2017-02-07 | 2020-02-14 | Ｊｆｅスチール株式会社 | Hot metal desulfurization 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 |
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- 2013-03-13 KR KR1020147023669A patent/KR101529454B1/en active IP Right Grant
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108699614A (en) * | 2016-02-24 | 2018-10-23 | 杰富意钢铁株式会社 | The method of refining of molten steel in vacuum deaerator plant |
| CN108699614B (en) * | 2016-02-24 | 2020-11-03 | 杰富意钢铁株式会社 | Method for refining molten steel in vacuum degassing apparatus |
| 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 |
| TWI698532B (en) * | 2018-04-17 | 2020-07-11 | 日商日本製鐵股份有限公司 | Method for manufacturing molten steel |
| CN115335537A (en) * | 2020-04-01 | 2022-11-11 | 杰富意钢铁株式会社 | Decarburization refining method of molten steel under reduced pressure |
Also Published As
| Publication number | Publication date |
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| TWI490340B (en) | 2015-07-01 |
| KR101529454B1 (en) | 2015-06-16 |
| KR20140111710A (en) | 2014-09-19 |
| JP5382275B1 (en) | 2014-01-08 |
| JPWO2013137292A1 (en) | 2015-08-03 |
| CN104169442B (en) | 2015-12-30 |
| WO2013137292A1 (en) | 2013-09-19 |
| TW201404889A (en) | 2014-02-01 |
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