CN104531948B - Method of dephosphorization of molten iron - Google Patents
Method of dephosphorization of molten iron Download PDFInfo
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- CN104531948B CN104531948B CN201410697005.4A CN201410697005A CN104531948B CN 104531948 B CN104531948 B CN 104531948B CN 201410697005 A CN201410697005 A CN 201410697005A CN 104531948 B CN104531948 B CN 104531948B
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- dephosphorization
- molten iron
- slag
- source
- concentration
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Classifications
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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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—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
- C21C7/064—Dephosphorising; 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
Abstract
A method in which a smelting agent consisting mainly of a CaO source and an oxygen source are added to molten iron to conduct a dephosphorization treatment. In the method, the molten iron is dephosphorized so that the slag after the treatment has a basicity of 2.2-3.5, excluding 2.2, and a total iron concentration of 10-30 mass% and that the final treatment temperature of the molten iron is 1,320 DEG C or higher. Thus, the dephosphorization can be accelerated while ensuring a high manganese yield and the molten iron can be efficiently dephosphorized.
Description
The application be the application for a patent for invention of Chinese Application No. 200780006368.7 divisional application (original application send out
Bright entitled " dephosphorization method for molten iron ", the international filing date of original application is on 02 26th, 2007).
Technical field
The present invention relates to the dephosphorization of molten iron carried out as molten iron pretreatment (Hot Metal Pretreatment) is processed
(Dephosphorization) method.
Background technology
Converter process always is replaced to be widely used in the molten iron method for pretreating that the molten iron stage carries out dephosphorization treatment.This
It is that the lower limit for the treatment of temperature (certainly, exist can) be thermodynamicallyy carried out as the lower dephosphorisation reaction of refining temperature is more easy, more may be used
To carry out dephosphorization treatment with lesser amount of refining agent (Refining Agent).
It is general that in molten iron pretreatment, the solid oxygen source for adding ferrum oxide etc. first in molten iron carries out desiliconization process,
Adding refining agent (Dephosphorising agent and flux (fluxing agent)) after removing the slag generated during the desiliconization is processed is carried out at dephosphorization
Reason.The CaO systems refining agent of Calx etc. is used usually as the refining agent of dephosphorization treatment, (the oxidation of solid oxygen source is used as oxygen source
Ferrum etc.), gas oxygen.In addition, using torpedo hot metal mixer car, ladle (ladle) (steel loading bag), converter type container etc. as process container.
In existing dephosphorization of molten iron, in order to promote the slag making (fluxing) of CaO systems refining agent, addition is widely used
CaF2The method of (fluorite).But, in recent years from from the viewpoint of environmental conservation, have the liquate amount of F of the reinforcing in slag
The tendency of codes and standards, therefore seek to reduce CaF2Usage amount or do not use CaF2Operation (without F operate).
In operating without F, seek CaO slag making, maintain dephosphorization efficiency to be important, in order that the abundant slag making of CaO, typically exists
(low C/S operations) (for example, Unexamined Patent 9-143529 publication) is operated under basicity than relatively low slag.Further, since root
According to Thermodynamics treatmont temperature it is low when be beneficial to dephosphorisation reaction, so carrying out treatment temperature than relatively low operation to improve dephosphorization efficiency
(for example, JP 2000-8112 publication and JP 2002-309312 publication).
The content of the invention
But, during low C/S operations (or having reduced the low C/S operations for the treatment of temperature), it is desirable in limited process time
It is limited to improve dephosphorization rate.Even if in addition, it is assumed that dephosphorization rate can have raising to a certain degree, but depositing in low C/S operations
The problem that MnO concentration increases in slag, the Mn yield rates in dephosphorization operation are reduced.Therefore, in any case, carried out with prior art
When operating without F, 2 points is the problem for being difficult to take into account below：
A () promotes CaO slag making and obtains high dephosphorization rate,
B () guarantees high Mn yield rates.
But, (a), (b) this 2 points takes into account be not limited solely to the problem that is dephosphorization of molten iron, guaranteeing to include decarbonization process
It is also very important in terms of total Mn yield rates.That is, through dephosphorization operation and decarbonization process melting Mn concentration ratios
During higher steel, Mn Ores to be loaded in decarbonization process so as to reduce, improve the Mn concentration in molten steel, and it is above-mentioned by realizing
A (), the dephosphorization burden in decarbonization process are reduced, it is possible to carry out decarburization blowing with few quantity of slag, by also originating in for Mn Ores
The rising of Mn concentration in raw molten steel just becomes very easy, in addition, by realizing (b), just can be with few in decarbonization process
Mn Ores addition and the concentration of Mn in molten steel is improved to desired level, these results can make overall total of refine
Mn yield rates are significantly improved.
In addition, in Unexamined Patent 9-143529 publication, operating despite low C/S, but supplying powder body in bottom blowing mode
When can but obtain the good Mn yield rates of comparison.Although the trial that the mixing power brought to being blown into powder body carries out quantification does not have
Sweep all before one, but from empirically learning for example than being only blown into big many of mixing power that gas brought.Therefore the publication
The effect above is considered as the powerful mixing power brought by the powder body that its reason is bottom blowing.In fact, not entering in the publication
During row powder body bottom blowing, Mn yield rates very low (table 1 of the publication).
But, when powder body is supplied in bottom blowing mode, do not merely had to special equipment, and the loss in air port be severe.In order to
Change air port, it is necessary to stop converter, it is when the frequency is high, extremely uneconomical in operation.
Therefore, it is an object of the present invention to provide a kind of may insure high Mn yield rates while promoting dephosphorisation reaction, having
Effect ground carries out the little method of dephosphorization of molten iron, facility load, it is particularly a kind of in F sources addition as far as possible less or without F sources
Under conditions of the dephosphorization method for molten iron that can realize.
The present inventor is studied for the optimal dephosphorization treatment condition that can solve the problem that above-mentioned problem, and its result finds,
Make the basicity of the slag after process reach the high specific region of comparison and also make molten iron process outlet temperature reach prescribed level with
After upper, by the T.Fe concentration in slag after treatment it is very high under conditions of processed, it is possible to guarantee high Mn finished products
Rate, while promoting dephosphorisation reaction and carrying out effective dephosphorization of molten iron.Usually can consider with regard to the treatment conditions of dephosphorization of molten iron
Have it is following some：
When () improves the basicity of slag i, can produce the cost by caused by the increase of refining agent (CaO) input amount increases and essence
The problem of the slag making deficiency of refining agent etc.；
(ii), when improving treatment temperature, can produce dephosphorization efficiency reduces the problem with refractory matter loss in stove；
(iii) problem of ferrum yield rate reduction etc. can be produced during T.Fe concentration in raising slag；
But, the inventors discovered that, by audaciously being considered as operating not good conditional combination to rise by such
Come, it is possible to obtain uncertain effect as described above.
, based on such opinion, its main idea is as described below for the present invention.
(1) a kind of method of dephosphorization of molten iron, is to add the refining agent and oxygen source using CaO sources as main body, side in molten iron
Form the method that slag side carries out dephosphorization treatment, it is characterised in that at the end of at least up to above-mentioned dephosphorization treatment, the basicity of above-mentioned slag
(%CaO/%SiO2) more than 2.2 and below 3.5, T.Fe concentration is 10～30mass%, and the process terminal temperature of molten iron
Degree is more than 1320 DEG C.
(2) dephosphorization method for molten iron according to above-mentioned (1), it is characterised in that terminate at least up to above-mentioned dephosphorization treatment
When, the basicity (%CaO/%SiO of above-mentioned slag2) more than 2.2 and below 3.0.
(3) dephosphorization method for molten iron according to above-mentioned (1) or (2), it is characterised in that above-mentioned process outlet temperature is
1320 DEG C～1400 DEG C.
(4) dephosphorization method for molten iron according to any one of above-mentioned (1)～(3), it is characterised in that at least up to above-mentioned
At the end of dephosphorization treatment, the T.Fe concentration of above-mentioned slag is 15～25mass%.
(5) dephosphorization method for molten iron according to any one of above-mentioned (1)～(4), it is characterised in that with from titania source
And Al2O3At least one selected in source is used as a part for above-mentioned refining agent.
(6) dephosphorization method for molten iron according to above-mentioned (5), it is characterised in that titanium oxide with the slag after process (but change
It is counted as TiO2) and Al2O3The mode for adding up to 3～15mass% of content add from above-mentioned titania source and Al2O3Select in source
At least one selected.
(7) dephosphorization method for molten iron according to any one of above-mentioned (1)～(6), it is characterised in that the F of above-mentioned slag is dense
Degree is in below 0.2mass%.
(8) dephosphorization method for molten iron according to any one of above-mentioned (1)～(7), it is characterised in that make dephosphorization of molten iron extremely
P content (the composition specification value of steel) required by crude steel is below.
Description of the drawings
Fig. 1 is the seat of the relation between basicity C/S (transverse axis) of the slag after representing dephosphorization treatment and P removal rate (%) (longitudinal axis)
Mark on a map.
Fig. 2 is the relation between basicity C/S (transverse axis) of the slag after representing dephosphorization treatment and Mn yield rates (%) (longitudinal axis)
Coordinate diagram.
Fig. 3 is to represent the relation between dephosphorization treatment outlet temperature (DEG C) (transverse axis) of molten iron and P removal rate (%) (longitudinal axis)
Coordinate diagram.
Fig. 4 is to represent the pass between dephosphorization treatment outlet temperature (DEG C) (transverse axis) of molten iron and Mn yield rates (%) (longitudinal axis)
The coordinate diagram of system.
Fig. 5 is between the T.Fe concentration (mass%) (transverse axis) of the slag after representing dephosphorization treatment and P removal rate (%) (longitudinal axis)
Relation coordinate diagram.
Fig. 6 be the slag after representing dephosphorization treatment T.Fe concentration (mass%) (transverse axis) and Mn yield rates (%) (longitudinal axis) it
Between relation coordinate diagram.
Specific embodiment
Add method that dephosphorization treatment is carried out based on the refining agent and oxygen source in CaO sources in molten iron in the present invention
In, so that the basicity (=%CaO/%SiO of the slag after processing2, mass ratio is same as below) more than 2.2 and below 3.5,
T.Fe concentration is 10～30mass% and makes the mode that the process outlet temperature of molten iron is more than 1320 DEG C, molten iron is carried out
Dephosphorization treatment.In addition, the major part of slag is formed in dephosphorization treatment, but for example a part of slag can also be left by front furnace charge.
In the present invention, the basicity of the slag after making process as described above and T.Fe concentration, the process end of molten iron
This 3 condition optimizations of point temperature, it is possible to imitated with high Mn yield rates and dephosphorization according to the effect of following (I)～(III)
Rate carries out dephosphorization of molten iron.
(I) as the basicity of slag is higher or treatment temperature is higher, the Mn in molten iron more is difficult to be oxidized, so by improving
The basicity (more than 2.2) of slag and carry out more than 1320 DEG C of high-temperature process, it is possible to obtain high Mn yield rates.
(II) slag making of CaO can be promoted due to passing through high-temperature process, it is possible to fully given play to by raising slag
The raising effect of the dephosphorisation reaction that basicity is produced, in addition, by improving the T.Fe concentration in slag, can compensate by unfavorable to dephosphorization
High-temperature process caused by dephosphorization efficiency reduction, these as a result, it is possible to obtain high dephosphorization efficiency.Here, according to
Thermodynamics, the basicity of slag is higher or treatment temperature (molten iron temperature) is higher, the easier step-down of FeO concentration in slag, therefore into difficult
To improve the condition of T.Fe concentration.But, carry out under conditions of the basicity and treatment temperature by raising slag at the same time described later
It is special to operate, T.Fe concentration can be effectively improved, and high dephosphorization efficiency can be realized.
(III) when being increased due to the T.Fe concentration in slag, the oxygen position of slag is increased, so becoming the bar for being unfavorable for Mn yield rates
Part, but due to the effect dominant of above-mentioned (I), it is possible to obtain high Mn yield rates.
In addition, with the slag composition and process outlet temperature after process the reasons why carrying out regulation be, in dephosphorization treatment, its
At the end of value be control desired value, it is therefore contemplated that at least in the later stage of dephosphorization treatment, with the condition close at the end of
Carry out dephosphorisation reaction.
Hereinafter, the treatment conditions of the present invention are specifically described.
[summary of dephosphorization treatment and main aliment]
Add based on the refining agent and oxygen source in CaO sources in molten iron in the present invention and carry out dephosphorization treatment.Here,
So-called CaO sources refer to CaO or containing the Ca compound (CaCO that can form CaO3、Ca(OH)2、CaMgO2Deng) auxiliary material.Make
Quick lime is generally used for CaO sources, but limestone, Calx, dolomite, used slag (vessel slag, company can also be enumerated
Casting slag, ingot casting slag etc.).In addition, so-called " based on the refining agent in CaO sources " is referred to and for the CaO sources in refining agent to be converted into CaO
And containing refining agents more than 40 weight %.
Other compositions with regard to refining agent will be described in more detail below.
Can spray by overhead loading, in from plug-in type spray gun to molten iron, connect any of projection of top-blown spray gun etc.
Method to molten iron supply refining agent.In these, overhead loads, the projection using top-blown spray gun and they combines because of which
Equipment damage is little and preferred, in addition, can obtain sufficient effect by these methods.
In addition, using gas oxygen (oxygen or oxygen-containing gas) and/or solid oxygen source (such as iron ore, to roll as oxygen source
Iron scale processed, iron ore, dust powder (powder containing ferrous components reclaimed in the waste gas from blast furnace, converter, sintering circuit etc.)
Deng ferrum oxide).Wherein, can injection or bottom blowing etc. by the top blast from top blow oxygen lance and in molten iron for gas oxygen
Any means be fed in molten iron；For solid oxygen source, can be by overhead loading, from plug-in type spray gun to ferrum
In water, any means of injection, projection of connection top-blown spray gun etc. are fed in molten iron.In these, top blast (gas oxygen),
Overhead loads (solid oxygen source), the projection (solid oxygen source) using top-blown spray gun and their combination in any gets up
Wound is little and preferred, in addition, can obtain sufficient effect by these methods.
When particularly dephosphorization treatment is carried out with converter type container, the top blast of gas oxygen is carried out by top blow oxygen lance, as needed
It is general to supply solid oxygen source in aforementioned manners.In addition, in order to effectively carry out dephosphorization, preferably stir molten iron, the stirring typically by
Nozzle (air port) etc. of plug-in type spray gun or embedment furnace bottom is blown into the gas of noble gases or oxygen etc. to be stirred.
[basicity of slag]
In the present invention, by carrying out the high-temperature process of 1320 DEG C (process outlet temperature of molten iron) more than and making process
The basicity of slag afterwards is more than 2.2, it is possible to obtain high Mn yield rates in dephosphorization operation as described above, simultaneously because Jing is high
Temperature processes the slag making that can promote CaO, it is possible to fully given play to carrying by the dephosphorization efficiency of the basicity generation for improving slag
High effect.But, when the basicity of the slag after process is more than 3.5, the shared ratio in slag of solid phase is raised, and reactivity is reduced, and is led
Cause dephosphorization bad.From this viewpoint, the basicity of the slag after preferred process is below 3.5.
For the above reasons, in the present invention process after slag basicity more than 2.2 and below 3.5, more preferably 2.5
～3.0.
These, can confirm for example, by following experiment.
(experiment 1)
With converter type container (300ton) to giving the blast-melted of desiliconization process to carry out dephosphorization treatment.In the dephosphorization treatment
In, overhead is loaded as the quick lime of the CaO main bodys for not containing the Fluorine sources such as fluorite of Dephosphorising agent.Then, supplied with top-blown spray gun
Oxygen, and overhead loads the solid oxygen source based on iron ore.Oxygen (purity oxygen) send oxygen condition be 15000～
40000Nm3/hr.Oxygen unit consumption beyond oxygen necessary to desiliconization is eliminated after be 12Nm3/ t molten iron.The input of adjustment quick lime
Amount, makes basicity C/S of slag be changed to 1.7～4.1.In addition, in the way of the molten iron temperature after to make dephosphorization treatment is 1350 DEG C, adjusting
The supply ratio of whole gas oxygen source and solid oxygen source.
In managing in this place, in molten iron, the target of the P removal rate of phosphorus is more than 80%, and in molten iron, the target of Mn yield rates is 30%
More than.In addition, the yield rate (%) of P removal rate (%) and Mn is defined by the formula.
(P removal rate)={ [(before processing P concentration)-(P concentration after process)]/(before processing P concentration) } × 100
(Mn yield rates)=[(Mn concentration after process)/(before processing Mn concentration)] × 100
In addition, the value of P removal rate and Mn yield rates does not depend on P concentration, the here as unit of Mn concentration, P in above-mentioned formula
Concentration and Mn concentration are using the mass% relative to molten iron.
Basicity C/S for making transverse axis be the slag after processing, will have studied the relation between P removal rate (%) and Mn yield rates (%)
Result be shown in Fig. 1 and Fig. 2.If according to so, when basicity C/S of slag is below 2.2, P removal rate and Mn yield rates are in low
Position.In contrast, basicity C/S of slag more than 2.2 and below 3.5 in scope when, P removal rate and Mn yield rate both of which reach
Desired value.But, when basicity C/S of slag is more than 3.5, P removal rate is reduced again.In addition, understanding that basicity C/S of especially slag exceedes
2.2 and when below 3.0, its result is that the deviation of P removal rate is little and stable.
In addition, replacing the overhead of refining agent in above-mentioned example with refining agent of the top-blown spray gun projection based on calcium lime powder
During loading, it is also possible to see same tendency.
As the control method of basicity C/S of slag, in addition to the above-mentioned input amount for controlling CaO sources, also control
The known SiO such as Silicon stone and brick bits2In molten iron of the input amount, regulation in source by prior desiliconization process or by input FeSi alloys
The method of Si concentration etc..
[dephosphorization treatment outlet temperature]
In the present invention, the process outlet temperature by carrying out molten iron is that more than 1320 DEG C of high-temperature process promotes CaO
Slag making, thus can fully give play to the raising effect of dephosphorization efficiency brought by the basicity for improving slag.In addition, according to heat
Mechanics, also becomes the good condition of Mn yield rates.In addition, from this viewpoint, more preferably process outlet temperature 1350 DEG C with
On.On the other hand, when outlet temperature is processed more than 1400 DEG C, become the temperature conditionss for being unfavorable for dephosphorization, in order to compensate this point,
Substantial amounts of slag is required, is as a result that the Mn yield rates in follow-up decarbonization process are greatly lowered.In addition, this tendency is at place
Reason outlet temperature is particularly significant when being more than 1420 DEG C, and the huge quantity of slag is required.According to the reasons why the above, in the present invention
The process outlet temperature of molten iron more than 1320 DEG C, preferably more than 1350 DEG C, additionally, it is preferred that its upper limit is 1400 DEG C.
This point, can confirm for example, by following experiment.
In addition, when using converter type container dephosphorization, due to the relation of equipment, the process outlet temperature of molten iron generally exists mostly
Tap.Thus, the temperature determined to after ladle of tapping is also adopted by the present invention.The value ratio is typically in converter
Measured value in type container is low about 20 DEG C.
(experiment 2)
With converter type container (300ton) to giving the blast-melted of desiliconization process to carry out dephosphorization treatment.In the dephosphorization treatment
In, overhead is loaded as the quick lime of the CaO main bodys for not containing the Fluorine sources such as fluorite of Dephosphorising agent.So that slag after dephosphorization treatment
Basicity is the input amount that 3.0 mode adjusts quick lime.Then, oxygen is supplied with top-blown spray gun, and overhead loads with iron mine
Solid oxygen source of the stone for main body.The oxygen condition of sending of oxygen (purity oxygen) is 15000～40000Nm3/hr.Oxygen unit consumption is being eliminated
It is 12Nm after beyond oxygen necessary to desiliconization3/ t molten iron.The supply ratio of adjustment gas oxygen source and solid oxygen source, makes the process of molten iron
Outlet temperature is changed to about 1310～1430 DEG C.
Process outlet temperature (DEG C) for making transverse axis be molten iron, will have studied between P removal rate (%) and Mn yield rates (%)
Relation is shown in Fig. 3 and Fig. 4.
If higher according to outlet temperature so, is processed, the Mn yield rates in dephosphorization treatment are more improved, but P removal rate is got over
Reduce.Understand that it is to process eventually to take into account the P removal rate of phosphorus in the molten iron condition of Mn yield rates more than 30% more than 80%, in molten iron
Point temperature is in the range of 1320～1400 DEG C.Also know that especially more than 1350 DEG C when, the deviation of the lower limit of Mn yield rates is little
And it is stable.
In addition, projecting refining agent based on calcium lime powder to replace the overhead of refining agent in above-mentioned example by top-blown spray gun
During loading, it is also possible to see same tendency.
As the control method of the dephosphorization treatment terminal of molten iron, except above-mentioned gas oxygen source and the solid oxygen source of adjusting
Supply ratio in addition, also adjusts the input amount of the source of iron of old metal etc., the method for adjusting the input amount of carbon materials etc. etc..
[the T.Fe concentration of slag]
In the present invention, the T.Fe concentration of the slag after making process can be compensated by dephosphorization in more than 10mass%
Unfavorable high-temperature process caused by dephosphorization efficiency reduction, arrange in pairs or groups with the optimization of the basicity of slag as described above, can obtain
To high dephosphorization efficiency.In addition, from this viewpoint, the lower limit of more preferably T.Fe concentration is 15mass%.On the other hand, process
When the T.Fe concentration of slag afterwards is more than 30mass%, the ferrous components discharged together with slag are increased, it is impossible to ignore the yield rate of ferrum
Reduce.In addition, from this viewpoint, the upper limit of more preferably T.Fe concentration is 25mass%.According to the reasons why above-mentioned, in the present invention
In, the T.Fe concentration of the slag after process is 10～30mass%, preferably 15～25mass%.
As described above, according to thermodynamics, the basicity of slag is higher or treatment temperature (molten iron temperature) is higher, the FeO in slag
Concentration is more easy to be low, therefore becomes the condition for being difficult to improve T.Fe concentration.In addition, the present invention process after slag basicity and place
Under conditions of reason outlet temperature, in order that the T.Fe concentration in the slag after processing is more than 10mass%, it is necessary to carry out for carrying
T.Fe concentration cannot be brought up to more than 10mass% by the positive operation (action) of high T.Fe concentration, the not operation.
Can enumerate as the special operation is for example carried out by the throwing for sending oxygen, control iron oxide source for sending oxygen rifle with soft blow
The method for entering amount etc..
It is so-called referred to reduce by the soft blow of top blow oxygen lance send oxygen speed by the rifle, and reduce by the gas oxygen of top blast
The dynamic pressure (such as below 0.03MPa, preferred below 0.02MPa) of the molten iron level that kinetic energy is produced.In addition, the dynamic pressure of molten iron level
Pd (MPa) is using the value calculated by following formula.
Pd=UO×(de/HL)×COSθ×(1/2)×(1/(0.016+0.19/Pi))/10
UO:Oxygen lance nozzle exit velocity (m/s)
de:Oxygen lance nozzle outlet diameter (m)
HL:Oxygen rifle height (m)
θ:Oxygen lance nozzle central shaft and angle (rad) formed by oxygen rifle central shaft
Pi:The inlet-pressure (MPa) of oxygen lance nozzle.
During according to so carrying out sending oxygen by top blow oxygen lance with soft blow, it is sufficiently carried out, to the oxygen supply in slag, slag being made
In T.Fe be maintained high concentration.As long as the latter half at least in dephosphorization treatment carries out soft blow.
In addition, in slag put into ferrum oxide method in, in order to ensure process latter half slag in T.Fe concentration,
Iron oxide source is put into the latter half or latter stage of process more.Now, for example, throw after the intermediate point in (blowing process) during processing
Enter more than the 2/3 of predetermined ferrum oxide input amount.
Can be using iron ore, mill tap, iron ore, dust powder etc. as iron oxide source, putting into method as which can
To be loaded using overhead, by top-blown spray gun projection or injection etc. any means.
The effect of T.Fe concentration, for example, can pass through following experimental verification.
(experiment 3)
With converter type container (300ton) to giving the blast-melted of desiliconization process to carry out dephosphorization treatment.In the dephosphorization treatment
In, overhead is loaded as the quick lime of the CaO main bodys for not containing the Fluorine sources such as fluorite of Dephosphorising agent.So that slag after dephosphorization treatment
Basicity is 3.0 mode, adjusts the input amount of quick lime.Then, oxygen is supplied with top-blown spray gun, and overhead loads with iron mine
Solid oxygen source of the stone for main body.The oxygen condition of sending of oxygen is 15000～40000Nm3/hr.Oxygen unit consumption is to eliminate desiliconization musted
It is 12Nm after beyond the oxygen for needing3/ t molten iron.In addition, the molten iron temperature after to make dephosphorization treatment is to adjust gas in the way of 1350 DEG C
The supply ratio of oxygen source and solid oxygen source.Now, the investing method of solid oxygen source is carried out into various change, makes the slag after process
T.Fe concentration change is to about 5～28%.Particularly T.FeWhen concentration reaches more than 15mass%, (blowing during processing
Period) intermediate point after put into more than the 2/3 of predetermined solid oxygen source input amount, when target T.Fe is higher, more make centre
The later input ratio of point increases.
Make the T.Fe concentration (mass%) that transverse axis is the slag after processing, the pass between P removal rate (%) and Mn yield rates (%)
System is shown in Fig. 5 and Fig. 6.If according to so, it is known that as long as T.Fe concentration is in more than 10mass%, P removal rate and Mn yield rates are all
Target can be met.
As it was previously stated, when the concentration of FeO increases in slag, as the oxygen position of slag is high, becoming and being unfavorable for guaranteeing Mn yield rates
Condition, but, as basicity in the present invention based on slag and the optimized effect for processing outlet temperature are had the advantage, so
High Mn yield rates can be obtained.In addition, understanding that especially T.Fe concentration is in more than 15mass%, the deviation of Mn yield rates is little
And it is stable.
In addition, replacing the overhead of refining agent in above-mentioned example with refining agent of the top-blown spray gun projection based on calcium lime powder
During loading, it can be seen that same tendency.
[additive of refining agent]
In the present invention, it is preferred to by using substantially not containing F sources (CaF2Deng) refining agent or added using F sources
The few refining agent of amount, so that the F concentration of slag is below 0.2mass% after during process, in the present invention, even if using so
Refining agent, it is also possible to obtain high dephosphorization efficiency.Alternatively, it is also possible to the F concentration of slag is managed with the value after process.
Here, so-called refining agent refers in the F sources that substantially do not contain without F sources, as such, it can be that for example as inevitably
Impurity etc. and contain a small amount of F sources.
In addition, due to by by titania source and/or Al in the present invention2O3Source is used as a part for refining agent, is promoted
The slag making of CaO systems refining agent, also makes the oxygen position of slag also rise, so also improving the dephosphorizing capacity of slag.As a result, because entering
One step promotes dephosphorisation reaction and can be more effectively carried out dephosphorization of molten iron.That is, due to titania source and/or Al2O3Source
Function with the slag making accelerator as CaO systems refining agent, so substantially not containing F sources or F sources using as described above
Measure especially effective during few refining agent.
Titanium oxide has TiO, TiO2、Ti2O3、Ti3O5Deng form, but can also be any one form.As titanium oxide
The material containing titanium oxide in source can be enumerated for example：Iron ore, titanium iron ore (ilmenite), titania ore (rutile), contain
Iron ore of titanium oxide etc., it is possible to use more than a kind in them.In addition, in them, due to iron ore be usually particle diameter 1mm with
Under microgranule, promptly can melt in reaction vessel, so particularly preferably.In addition, by iron ore is added in slag, also
The T.Fe concentration in slag can be improved, that is to say, that as (titanium iron ore contains aerobic also with the function as iron oxide source
Change titanium iron ore similarly), so from this point it is also preferred that.Grade is different because of the place of production for iron ore, but typically contain 5～
The TiO of 8mass% or so2, high can also contain 13mass% or so.On the other hand, titanium iron ore and rutile generally contain
There is the TiO of more than 30mass%2。
Preferably used as the material containing titanium oxide of titania source with TiO2Conversion meter, the oxygen containing more than 3mass%
Change the material of titanium.Titanium oxide content is with TiO2Conversion meter, less than the material of 3mass%, it is difficult to be promoted CaO systems refining agent and make
The effect of slag, when will obtain effect, addition increases, and the quantity of slag just increases, and can cause the problem of Mn yield rates reduction etc..Therefore,
In any case, the micro material containing titanium oxide degree is not suitable as titania source (material containing titanium oxide).
In addition, as Al2O3Aluminium oxide can be contained using commercially available calcium aluminium salt system flux, aluminum ash, bauxite etc. in source
Ore etc..Alternatively, it is also possible to using such steel making working procedure containing high concentration aluminium oxide such as ingot casting slag, 2 refining slags, brick bits
Side-product.As Al2O3Source is preferably with Al2O3Conversion meter is containing more than 20mass%.
As titania source and/or Al2O3The addition in source, the titanium oxide in slag after preferred process is (with TiO2Conversion)
And Al2O3Content add up to below 15mass%.When totalling over 15mass% of content, the CaO needed for dephosphorisation reaction become
It is thin, reduce can dephosphorizing capacity.In addition, in the operation of common dephosphorization, both totals in slag inevitably contain
1.0～2.5mass%, but, during less than 3mass%, the slag making facilitation effect of CaO systems refining agent will be insufficient.Therefore, it is excellent
The titanium oxide in slag after choosing process is (with TiO2Conversion) and Al2O3Content total in more than 3mass%.
When dephosphorization treatment, in addition to the foregoing, MgO sources etc. can also be added for the purpose of protecting body of heater.
[other]
Can be using converter type container, ladle, mixed iron blast etc. arbitrarily as the container of the dephosphorization of molten iron for implementing the present invention
Container, but from substantially ensuring that free space (free board:In container from above the liquid level or slag of motlten metal to
Chamber wall upper end it is more than needed) from the viewpoint of, most preferably converter type container.
In addition, the dephosphorization of molten iron of the present invention is readily adaptable for use in any one following mode：
Dephosphorization treatment is separately carried out (discontinuously carry out) using different containers (for example, converter type container) and is taken off
The mode of carbon process；
Middle deslagging is inserted using same converter type container and the mode of dephosphorization treatment and carbonization treatment is continuously carried out.
Molten iron process time is different according to the shape and capacity of container, but preferably 5～30 minutes or so.
In addition, it is proposed, according to the invention, can easily make dephosphorization of molten iron be refined to the (composition of steel of the P content required by crude steel
Specification value) below.Due to by so making P content (the composition specification value of steel) required by dephosphorization of molten iron to crude steel below,
Dephosphorization need not be substantially carried out in the decarbonization process for proceeding, it is possible to which Decarburising and refining is carried out with the considerably less quantity of slag, its
As a result, when particularly addition Mn Ores improve the concentration of Mn in molten steel, it is possible to achieve high Mn yield rates.Further, since can
So that Decarburising and refining is simplified very much, refining time can also be shortened, it is possible to improve as overall steel making ability.
In addition, as the example of the P content required by crude steel, can enumerate below 0.03mass% (general steel),
Below 0.015mass% (Low-phosphorus Steel) etc..
[embodiment]
(embodiment 1)
Dephosphorization is carried out to blast-melted (Mn concentration 0.3mass%) of giving desiliconization to process with converter type container (300ton)
Process.In the dephosphorization treatment, overhead is loaded as the quick lime of the CaO main bodys for not containing the Fluorine sources such as fluorite of Dephosphorising agent.So
Afterwards, oxygen is supplied with top-blown spray gun, and overhead loads the solid oxygen source based on iron ore.The oxygen condition of sending of oxygen is
15000～40000Nm3/hr.Oxygen unit consumption beyond oxygen necessary to desiliconization is eliminated after be 12Nm3/ t molten iron.Solid oxygen source
Input is carried out according to following 2 kinds of situations：Predetermined input amount (mean allocation) is put in whole duration of blast equably；With
More than the 2/3 of predetermined input amount is put into after intermediate point during refine.
After dephosphorization blowing loading molten iron in other converter type containers (300ton) carries out carbonization treatment.Decarburization is blown
When, overhead puts into the Mn Ores as Mn sources.The input amount of Mn Ores is the pure composition Mn of molten steel 4kg per ton.
P removal rate and Mn yield rates after dephosphorization blowing is shown in table 1 together with dephosphorization treatment condition.In addition, after dephosphorization-decarburization
Total Mn yield rates be also shown in table 1 in the lump.Total Mn yield rates after dephosphorization-decarburization are calculated by following formula.
(total Mn yield rates)={ (Mn concentration after decarburization)/[(Mn concentration before dephosphorization)+(Mn concentration is put into during decarburization)] }
×100
Table 1
* 1) incline to latter half：More than the 2/3 of predetermined input amount is put into after intermediate point during blowing
Mean allocation：Predetermined input amount is put into during whole blowing
P removal rate after having obtained taking into account dephosphorization blowing in example of the present invention is more than 85%, Mn yield rates are more than 40%
Result.As a result, loading in decarburization blowing, Mn concentration is high and loading P concentration is low, by being blown with the low quantity of slag
As a result refining is the total Mn yield rates after dephosphorization-decarburization also above 45%.
In contrast, in a comparative example, it is impossible to realize taking into account for high dephosphorization rate and high Mn yield rates.As a result, de-
In carbon blowing, loading Mn concentration is low and loads P concentration height, the blowing due to being the high quantity of slag, so total after dephosphorization-decarburization
Mn yield rates be in low level.
(embodiment 2)
Except a part of overhead of the refining agent as dephosphorization is loaded as the iron ore (TiO of titania source2Content：
7.5mass%) or as the ingot casting slag (Al of alumina source2O3Content：Beyond 30mass%), remaining enters similarly to Example 1
Row dephosphorization treatment and carbonization treatment.Using the TiO in the dephosphorized slag in the blowing of iron ore2Concentration is 4.0mass%, TiO2With
Al2O3Content adds up to 6.3mass%.In addition, using the Al in the dephosphorized slag in the blowing of ingot casting slag2O3Concentration is
4.5mass%, TiO2And Al2O3Content adds up to 6.1mass%.At P removal rate and Mn yield rates and dephosphorization after dephosphorization blowing
Manage bar part is also shown in table 2 together.In addition, the total Mn yield rates after dephosphorization-decarburization are shown in table 2 in the lump.No matter which example, all may be used
To obtain taking into account the result that P removal rate is more than 85%, Mn yield rates are more than 40% after dephosphorization blowing.As a result, obtaining
Result of the total Mn yield rates after dephosphorization-decarburization also above 45%.
Table 2
(embodiment 3)
Dephosphorization is carried out to blast-melted (Mn concentration 0.3mass%) of giving desiliconization to process with converter type container (300ton)
Process.In the dephosphorization treatment, oxygen is supplied with top-blown spray gun, and overhead loads the solid oxygen source based on iron ore.
Then, together with oxygen by top-blown spray gun project as Dephosphorising agent the CaO main bodys for not containing the Fluorine sources such as fluorite quick lime or
Person's Calcium Carbonate.The oxygen condition of sending of oxygen is 15000～40000Nm3/ hr, the projection amount of Dephosphorising agent is in 6000～30000kg/hr
In the range of adjust.Oxygen unit consumption beyond oxygen necessary to desiliconization is eliminated after be 12Nm3/ t molten iron.Oxygen is sent by top-blown spray gun
Carry out according to following 2 kinds of modes：Latter half during refining is 0.01～0.02MPa based on the dynamic pressure of the molten iron level for sending oxygen
(soft blow)；With (blow firmly) more than 0.03Mpa.
In addition, in a part of experiment material, being loaded as oxygen as a part of same overhead of the refining agent of dephosphorization
Change the iron ore (TiO of titanium source2Content：7.5mass%) or as the brick bits (Al of alumina source2O3Content：30mass%).
As a result it is shown in table 3.
Table 3
* 1) soft blow：Latter half during refining based on the dynamic pressure of the molten iron level for sending oxygen of top-blown spray gun be 0.01～
0.02MPa
Blow firmly：Latter half during refining, the dynamic pressure based on the molten iron level for sending oxygen of top-blown spray gun was more than 0.03MPa
P removal rate after having obtained taking into account dephosphorization blowing in example of the present invention is more than 85%, Mn yield rates are more than 40%
Result, in addition, obtaining result of the total Mn yield rates after dephosphorization-decarburization also above 45%.
In contrast, in a comparative example, it is impossible to realize taking into account for high dephosphorization rate and high Mn yield rates, as a result, dephosphorization-
Total Mn yield rates after decarburization are in low level.
(embodiment 4)
Dephosphorization is carried out to blast-melted (Mn concentration 0.3mass%) of giving desiliconization to process with converter type container (300ton)
Process.In the dephosphorization treatment, oxygen is supplied with top-blown spray gun, and from other the projection mouths and indifferent gas being located on the spray gun
Body projects the major part of the solid oxygen source based on scale together.And, do not contain the Fluorine sources such as fluorite as Dephosphorising agent
The quick lime of CaO main bodys is added according to following two modes：Overhead loads；Projected by top-blown spray gun together with oxygen.
The oxygen condition of sending of oxygen is 15000～40000Nm3/ hr, the projection amount of Dephosphorising agent is 6000～30000kg/hr's
In the range of adjust.Oxygen unit consumption beyond oxygen necessary to desiliconization is eliminated after be 12Nm3/ t molten iron.By top-blown spray gun send oxygen by
Carry out according to following 2 kinds：Latter half during refining is 0.01～0.02MPa (soft based on the dynamic pressure of the molten iron level for sending oxygen
Blow)；With (blow firmly) more than 0.03Mpa.
In addition, in a part of experiment material, being loaded as oxygen as a part of same overhead of the refining agent of dephosphorization
Change the ingot casting slag (Al of silicon source2O3Content：30mass%).
As a result it is shown in table 4.
Table 4
* 1) soft blow：Latter half during refining based on the dynamic pressure of the molten iron level for sending oxygen of top-blown spray gun be 0.01～
0.02MPa
Blow firmly：Latter half during refining, the dynamic pressure based on the molten iron level for sending oxygen of top-blown spray gun was more than 0.03MPa
* 2) overhead loads：From furnace roof hopper input CaO sources
Top blast is projected：By top-blown spray gun projection CaO sources
P removal rate after having obtained taking into account dephosphorization blowing in example of the present invention is more than 85%, Mn yield rates are more than 40%
Result, in addition, obtaining the result of the total Mn yield rates after dephosphorization-decarburization above 45%.
In contrast, in a comparative example, it is impossible to realize taking into account for high dephosphorization rate and high Mn yield rates, as a result, with de-
Total Mn yield rates after phosphorus-decarburization are in low level.
According to the present invention, the basicity and T.Fe concentration of the slag after making process, this 3 of the process outlet temperature of molten iron
Condition optimization, it is possible to guarantee high Mn yield rates, while promote dephosphorisation reaction, so as to carry out effective dephosphorization of molten iron.
In addition, by making the P content (the composition specification value of steel) required by dephosphorization of molten iron to crude steel below, in decarbonization process
In substantially without dephosphorization, it is possible to the decarburization quantity of slag is seldom changed, and can realize in whole refining procedures higher
Mn yield rates.
Claims (11)
1. a kind of dephosphorization method for molten iron, is to add refining agent and oxygen source the side of dephosphorization treatment is carried out when slag is formed in molten iron
Method, wherein, the refining agent is by CaO sources and can arbitrarily select the SiO for adding2Source, F sources, titania source, Al2O3Source and with
The MgO sources added are selected to constitute for the purpose of protection body of heater,
At the end of at least up to the dephosphorization treatment, the basicity of the slag is %CaO/%SiO2More than 2.5 and below 3.0,
T.Fe concentration is 10～30mass%, F concentration in below 0.2mass%,
And, the process outlet temperature of molten iron is more than 1320 DEG C.
2. dephosphorization method for molten iron according to claim 1, wherein, the CaO sources are selected from quick lime i.e. CaO, limestone
That is CaCO3, Calx be Ca (OH)2, it is dolomite, one kind or two or more in vessel slag.
3. dephosphorization method for molten iron according to claim 1 and 2, wherein, the process outlet temperature is 1320 DEG C～1400
℃。
4. dephosphorization method for molten iron according to claim 1 and 2, wherein, at least up to the dephosphorization treatment at the end of, it is described
The T.Fe concentration of slag is 15～25mass%.
5. dephosphorization method for molten iron according to claim 1 and 2, wherein, will be from titania source and Al2O3Select in source to
Few a kind of part as the refining agent is used.
6. dephosphorization method for molten iron according to claim 5, wherein, add from the titania source and Al2O3Select in source
At least one so that at the end of at least up to the dephosphorization treatment, the titanium oxide of the slag is converted into TiO2Obtained by content and
Al2O3Content add up to 3～15mass%.
7. dephosphorization method for molten iron according to claim 1 and 2, wherein, the F sources are CaF2。
8. dephosphorization method for molten iron according to claim 1 and 2, wherein, make P content required by dephosphorization of molten iron to crude steel with
Under, i.e., below the composition specification value of steel.
9. dephosphorization method for molten iron according to claim 1 and 2, wherein, the SiO2Source is a kind or 2 in Silicon stone and brick bits
Kind, control the SiO2The input amount in source, controls the basicity of the slag.
10. the dephosphorization method for molten iron according to any one of claim 1,2 and 6, wherein, the titania source be selected from
Iron ore, titanium iron ore, titania ore, with TiO2The titanium iron ore containing oxidation of conversion titanium oxide of the meter containing more than 3mass%
In it is one kind or two or more.
11. dephosphorization method for molten iron according to any one of claim 1,2 and 6, wherein, the Al2O3Source is selected from calcium
It is one kind or two or more in aluminium salt system flux, aluminum ash, bauxite, ingot casting slag, 2 refining slags, bricks bits.
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| KR101237487B1 (en) * | 2010-10-07 | 2013-02-26 | (주)유진에코씨엘 | Method for dephosphorsing during pre-treating pig iron using waste materials of steel making process |
| KR101677341B1 (en) * | 2014-12-03 | 2016-11-18 | 주식회사 포스코 | Highly efficient method for hot metal pretreatment |
| KR102189097B1 (en) * | 2016-12-26 | 2020-12-09 | 닛폰세이테츠 가부시키가이샤 | Pre-treatment method of molten iron and manufacturing method of ultra-low-tough steel |
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| CN1046139C (en) * | 1997-10-08 | 1999-11-03 | 冶金工业部钢铁研究总院 | Pre-dephosporizing method for molten iron |
| JP2002309310A (en) * | 1998-06-18 | 2002-10-23 | Nkk Corp | Method for producing low-phosphorous molten iron |
| JP2000345226A (en) * | 1999-06-02 | 2000-12-12 | Sumitomo Metal Ind Ltd | Method for dephosphorizing molten iron |
| JP2001040409A (en) * | 1999-07-30 | 2001-02-13 | Nippon Steel Corp | Method for dephosphorizing molten iron |
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