CN105899689B - Time sulphur prevention method of molten iron after desulfurization process - Google Patents
Time sulphur prevention method of molten iron after desulfurization process Download PDFInfo
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- CN105899689B CN105899689B CN201580004067.5A CN201580004067A CN105899689B CN 105899689 B CN105899689 B CN 105899689B CN 201580004067 A CN201580004067 A CN 201580004067A CN 105899689 B CN105899689 B CN 105899689B
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- Prior art keywords
- molten iron
- impeller
- desulfurization
- process container
- sulphur
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Classifications
-
- 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/06—Constructional features of mixers for pig-iron
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D27/00—Stirring devices for molten material
-
- 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
- C21C2300/00—Process aspects
- C21C2300/08—Particular sequence of the process steps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D27/00—Stirring devices for molten material
- F27D2027/002—Gas stirring
Abstract
Time sulphur caused by preventing the Decarburising and refining etc. for implementing the molten iron after desulfurization process and carrying out subsequent processing because generating and being suspended in the fine desulfurization slag in molten iron or the desulfurization slag being attached on the side wall of process container when desulfurization process in molten iron from the process of cast iron melting molten steel.In time sulphur prevention method of molten iron after desulfurization process of the invention, desulfurization process is implemented to the molten iron in process container using mechanical agitation type desulfurizer, then, inert gas is blown into molten iron from the gas ejection hole (6) on the impeller (4) that the mechanical agitation type desulfurizer is arranged in be stirred to molten iron (3), it is floated by the desulfurization slag that the stirring makes the desulfurization slag being suspended in molten iron and/or is attached on process container inner wall up to molten iron bath face, the desulfurization slag floated up is discharged from process container, then, molten iron in process container is transported to subsequent processing.
Description
Technical field
The present invention relates to Decarburising and refining of subsequent processing etc. is being carried out to the molten iron after implementation desulfurization process from cast iron melting
Prevented in the process of molten steel because in the desulfurization process of molten iron generate and after treatment suspension (suspension) it is medium in molten iron
And remain in the method that sulphur (re-sulfurization) is returned caused by the desulfurization slag in process container.
Background technique
In recent years, since the high purity of steel, the demand of multifunction increase, the steel grade of extremely low sulphur and/or extremely low phosphorus
Ratio increase.In such a case, it in steel making working procedure, needs do not leading to cost increase, the increase of slag yield etc.
In the case of the technology of melting is carried out to the steel grade of extremely low sulphur and/or extremely low phosphorus.
In the case where carrying out melting to low-sulfur steel, ultra-low sulphur steel etc., desulfurization process is carried out in the molten iron stage.In the desulfurization
After processing, because the high desulfurization slag of the sulfur content of desulfurization process generation is discharged from process container, then, the molten iron in process container
Supply dephosphorization treatment to subsequent processing, Decarburising and refining.In this case, although desulfurization slag is discharged from process container,
The fine desulfurization slag being suspended in molten iron can be brought to subsequent processing.In addition, being attached on the side wall of process container sometimes
Desulfurization slag is also brought to subsequent processing.Desulfurization process is reduction refining, in contrast, the dephosphorization treatment of subsequent processing and decarburization essence
Refining is refinement oxide, and therefore, being brought to sulphur contained by the desulfurization slag of subsequent processing can be oxidized and return in molten iron or molten steel.
The sulphur concentration of molten iron or molten steel rises as a result,.The phenomenon is known as " returning sulphur ".
The sulphur concentration of molten iron or molten steel because return sulphur due to get higher, to be unable to satisfy sulphur ingredient specification value in the case where,
It needs to remove the sulphur in molten steel in the double refining after the Decarburising and refining using converter.The molten iron carried out as double refining is de-
Sulphur refines compared with the desulfurization process of molten iron, and not only cost is higher, but also needs to carry out not scheduled molten steel desulfurizing refining, therefore
Productivity reduces.In addition, in the case where script carries out the premise of molten steel desulfurizing refining, when the sulphur concentration in molten steel is got higher,
It is also required to remove the sulphur of increased part and extends the refining time of comparable degree, productivity reduces.
That is, the iron in the case where wanting steadily to carry out melting to low-sulfur steel, ultra-low sulphur steel etc., after preventing desulfurization process
Value when returning sulphur, the sulphur concentration of molten iron maintaining to desulfurizing iron processing terminate of water is extremely important.
In the past, the desulfurization process of molten iron was usually by CaO fimily desulfurizing agent (lime based desulfurization
Flux the method into molten iron) is sprayed, CaO fimily desulfurizing agent and molten iron are stirred and are mixed using mechanical agitation type desulfurizer
The method of conjunction or metal Mg fimily desulfurizing agent is sprayed into method into molten iron etc..
In these desulfurization process, in order to improve the reaction efficiency of desulfurizing agent, desulfurizing agent is made by injection or mechanical stirring
It is dispersed in molten iron.In the good situation of dispersity of desulfurizing agent, desulphurization reaction is efficiently carried out.But de-
In the good situation of the dispersity of sulphur agent, fine desulfurizing agent can be more suspended in molten iron, in the partial size of the desulfurizing agent of dispersion
Hour, it will form the state for being not easy to float from molten iron.If stood molten iron for a long time after desulfurization process, can make to suspend
Fine desulfurizing agent in molten iron is floated to be removed from process container in molten iron bath face.But meeting is stood for a long time
Lead to the reduction of productivity and the reduction of molten iron temperature, therefore, in engineering without such disposition.
It has been known that there is be blown into and stir into molten steel to promote the floating upper and separation for the non-metallic inclusion being suspended in molten steel
Mix the method with gas.In the desulfurization process of molten iron, it was also proposed that utilize the technology of stirring gas.But in molten iron
Technology proposed in desulfurization process is not intended to the floating upper and separation for the non-metallic inclusion for promoting to be suspended in molten steel, and
It is the technology for utilizing stirring gas for other purposes.
For example, proposing following scheme in patent document 1: using the Mg-CaO-CaF in 80~90 mass %2Mixing
The Al of 10~20 mass % is added in object2O3Desulfurizing agent, which is sprayed together with gas into molten iron with transport,
Or in top surface addition (top addition on the bath surface) afterwards or while top surface is added by iron
Gas is blown into water and carries out bubbling stirring, to carry out desulfurization process to molten iron.In addition, propose in patent document 2 as
Desulfurizing agent: being blown into molten iron by lower scheme via spray gun, and by being immersed in the depth within the 1m of distance Iron water-bath face
Spray gun is blown into stirring gas, nearby strong mixing is carried out to the interface of slag and molten iron, to carry out desulfurization to molten iron.
But technology disclosed in Patent Document 1 is that the desulfurization slag for being easy slagging-off is formed and using above-mentioned desulfurizing agent
Carry out the technology of anti-non-return sulphur, being blown into for stirring gas is anti-for desulfurizing agent added by promoting by stirring and molten iron
It answers.In addition, being blown into for stirring gas in patent document 2 is to be stirred with molten iron the floating desulfurizing agent on molten iron
It mixes.That is, patent document 1,2 is all not configured to the floating upper and separation for the fine desulfurization slag for promoting to be suspended in molten iron.In addition,
In patent document 1,2, need to stir the spray gun with gas, do not use stirring gas under the premise of carry out, using general
Mechanical agitation type desulfurizer carry out desulfurization process in the case where, there is also asking for the spray gun for needing new stirring gas
Topic.
In addition, it is also proposed that following method: when carrying out desulfurization process to molten iron using mechanical agitation type desulfurizer, no
The spray gun of stirring gas is set, molten iron is stirred with gas using stirring.For example, propose in patent document 3 as
Lower method: being not provided with spray gun, from the impeller of mechanical agitation type desulfurization device, direction of rotation that blade is arranged in opposite location
Ejiction opening, desulfurizing agent is blown into molten iron with transport together with gas and carries out desulfurization.In addition, mentioning in patent document 4
Go out following method: being not provided with spray gun, it is same carbon material to be blown into together with gas with transport from the rotary shaft bottom surface of impeller
Shi Jinhang desulfurization process.
But being blown into for the desulfurizing agent in patent document 3 is in order to by blowing to the high region of stirring turbulent energy density
Enter desulfurizing agent and promotes desulphurization reaction.In addition, being blown into for carbon material in patent document 4 is to promote carbon material in molten iron
Dissolution.That is, patent document 3,4 is all to be blown into stirring in desulfurization process to promote desulphurization reaction with gas or promote carbon material
The technology of dissolution in molten iron stops being blown into for stirring gas after desulfurization process.Therefore, in patent document 3 and patent
In technology disclosed in document 4, the floating upper and separation for the fine desulfurizing agent being suspended in molten iron will not be promoted.Therefore, patent text
The floating of fine desulfurization slag that 3,4 are all not configured to promote to be suspended in after desulfurization process in molten iron is offered to go up and separate.
That is, not suggesting that the floating upper of the fine desulfurization slag for promoting to be suspended in molten iron after desulfurization process in the past and dividing
From, prevent the technology for returning sulphur of the molten iron after desulfurization process.
Existing technical literature
Patent document
Patent document 1: Japanese Unexamined Patent Publication 8-269519 bulletin
Patent document 2: Japanese Unexamined Patent Publication 4-235210 bulletin
Patent document 3: Japanese Unexamined Patent Application 52-85013 bulletin
Patent document 4: Japanese Unexamined Patent Publication 2005-200762 bulletin
Summary of the invention
Problem to be solved by the invention
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide to implement desulfurization process after molten iron into
Decarburising and refining of row subsequent processing etc. is prevented from the process of cast iron melting molten steel because generating and hanging in the desulfurization process of molten iron
Float on the side that sulphur is returned caused by the fine desulfurization slag in molten iron and/or the desulfurization slag being attached on the side wall of process container
Method.
The method for solving problem
The gist of the invention for solving the above problems is as described below.
[1] time sulphur prevention method of the molten iron after a kind of desulfurization process, wherein
Desulfurization process is implemented to the molten iron in process container using mechanical agitation type desulfurizer,
Then, it is blown from the gas ejection hole on the impeller that above-mentioned mechanical agitation type desulfurizer is arranged in into above-mentioned molten iron
Enter inert gas to be stirred to molten iron, the desulfurization slag being suspended in molten iron is made by the stirring and/or is attached to processing appearance
Desulfurization slag on device inner wall is floated up to molten iron bath face,
The desulfurization slag floated up is discharged from process container,
Then, the molten iron in process container is transported to subsequent processing.
[2] time sulphur prevention method of the molten iron after the desulfurization process as described in above-mentioned [1], wherein sprayed in above-mentioned gas
The position in hole rotates above-mentioned impeller in the state of being impregnated in molten iron, adjusts the setting position of impeller and/or the revolving speed of impeller, with
The rotation for forming the rotation from the standby fluid level of the molten iron in above-mentioned process container to the above-mentioned impeller by being impregnated in the molten iron
The distance of the recess at whirlpool center is smaller than from above-mentioned standby fluid level to the distance of impeller upper end.
[3] time sulphur prevention method of the molten iron after the desulfurization process as described in above-mentioned [2], wherein pass through following formulas (1)
~formula (4) calculates the distance of the recess from above-mentioned standby fluid level to vortex core,
Wherein, in these formulas, H is the distance (m) of the recess from the standby fluid level of molten iron to vortex core, and N is impeller
Revolving speed (beat/min), D be process container internal diameter (m), θ be impeller blade inclination angle (rad), b be impeller height
(m), d is the rotating diameter (m) of impeller, npFor the blade the piece number of impeller, g is acceleration of gravity (=9.8m/s2), Re is Reynolds
Number (zero dimension), ρ are the density (kg/m of molten iron3), μ is the viscosity (Pas) of molten iron.
[4] time sulphur prevention method of the molten iron after the desulfurization process as described in any one of above-mentioned [1]~above-mentioned [3],
In, two or more is arranged in above-mentioned gas squit hole on each impeller, in the rotational circle side side of the blade of impeller, changes
The height and position of vertical direction it is configured.
Invention effect
According to the present invention, it is stirred by what is carried out using the inert gas sprayed from the gas ejection hole being arranged on impeller
It mixes, makes to remain in the desulfurization slag in process container and force that the desulfurization slag floated up is discharged from process container on floating, then,
Molten iron is supplied to the dephosphorization treatment of subsequent processing, Decarburising and refining.As a result, in dephosphorization treatment, the decarburization essence for implementing subsequent processing
When refining, the major part of the desulfurization slag of sulphur is caused back to be removed, dephosphorization treatment can be reduced, return sulphur in Decarburising and refining.As a result,
It is and previous even if being also able to carry out the melting of ultra-low sulphur steel in the molten steel stage not firm desulfurizing and refining applied as double refining
It compares, can be realized the substantially reduction and the raising of productivity of manufacturing cost.
Detailed description of the invention
Fig. 1 is the skeleton diagram for indicating to implement an example of the floating upper-separation process of desulfurization slag.
Fig. 2 is synoptic diagram when being stirred in mechanical agitation type desulfurizer using impeller and forming vortex.
Specific embodiment
Hereinafter, the present invention is specifically described.
In the desulfurization process using the molten iron of CaO fimily desulfurizing agent, in order to improve reaction interface area, in process container
CaO fimily desulfurizing agent and molten iron are stirred, are dispersed in CaO fimily desulfurizing agent in molten iron.It is well known as CaO fimily desulfurizing agent
CaO fimily desulfurizing agent can with there is no problem use, and quick lime (CaO), lime stone (CaCO can be used for example3), white lime
(Ca(OH)2), dolomite (CaO-MgO), the fluorite (CaF for mixing the mass % of about 5 mass %~about 30 in these materials2), oxygen
Change aluminium (Al2O3) etc. substance obtained from CaO fluxing agent (fluxing agent for CaO).
Sulphur in molten iron carries out instead with the CaO fimily desulfurizing agent being dispersed in molten iron according to the reaction equation of " CaO+S → CaS+O "
It answers, generates the high desulfurization slag of the sulphur concentration containing CaS.The desulfurization slag floats the iron in molten iron bath face at the end of desulfurization process
Water-bath face is desulfurized slag covering.Utilize slag remover (slag dragger) etc. from process container after desulfurization process the desulfurization slag
Middle discharge (referred to as " desulfurization slag deslagging process ").After the desulfurization slag deslagging process, the molten iron in process container is transported to down
Dephosphorization treatment process, the Decarburising and refining process of one process.
But ascent rate partial size according to Stokes' law and to desulfurization slag of the desulfurization slag in molten iron is proportional.
Therefore, the ascent rate for being suspended in the fine desulfurization slag in molten iron is slow, is suspended in the state in molten iron in fine desulfurization slag
Lower end desulfurization process.In addition, the desulfurization slag being attached on process container inner wall is also not easy on floating, it is attached to process container inner wall
On the major part of desulfurization slag be also to be remained as former state at the end of desulfurization process.The fine desulfurization slag that is suspended in molten iron and attached
Will not be discharged from process container in above-mentioned desulfurization slag deslagging process in the major part of the desulfurization slag on process container inner wall
And remain in process container.
Dephosphorization process, the Decarburising and refining process of subsequent processing are refinement oxide.Therefore, in desulfurization slag deslagging process not by
When the desulfurization slag for being discharged and remaining in process container is brought to the dephosphorization treatment process of subsequent processing, Decarburising and refining process, take off
CaS in sulphur slag is oxidized and generates CaO.Because the oxidation of CaS from the sulphur (S) that CaS is dissociated so that migrate to molten iron or molten steel, hair
What the sulphur concentration of molten iron or molten steel rose returns sulphur.
The present invention in order to prevent this time sulphur and complete, in the present invention, used in mechanical agitation type desulfurizer
After CaO fimily desulfurizing agent carries out desulfurization process to molten iron, using the mechanical agitation type desulfurizer after progress desulfurization process, from setting
It is blown in molten iron of the gas ejection hole on the impeller of mechanical agitation type desulfurizer into the process container after implementation desulfurization process
Enter inert gas to be stirred to molten iron, make the desulfurization slag being suspended in molten iron and/or is attached on process container inner wall
Desulfurization slag is forcibly floated up to molten iron bath face, and the desulfurization slag floated up is discharged from process container, then, will be in process container
Molten iron be transported to the dephosphorization treatment process and Decarburising and refining process of subsequent processing.
Herein, in the present invention, inert gas will be blown into molten iron from the gas ejection hole being arranged on impeller to come pair
Molten iron is stirred, the desulfurization slag to make the desulfurization slag being suspended in molten iron and/or be attached on process container inner wall is forced
Float the processing referred to as " the floating upper-separation process of desulfurization slag " up to molten iron bath face in ground.It should be noted that in the above description,
In mechanical agitation type desulfurizer after implementing desulfurization process, the floating upper-separation of desulfurization slag is followed by implemented in desulfurization process
Process, but can also be in the mechanical agitation type desulfurizer separated with the mechanical agitation type desulfurizer after implementation desulfurization process
Implement the floating upper-separation process of desulfurization slag.Certainly, when being handled using same mechanical agitation type desulfurizer, productivity is higher,
To preferably.
In Fig. 1, an example for implementing the floating upper-separation process of desulfurization slag is shown with skeleton diagram.In Fig. 1, symbol 1 is platform
Vehicle, 2 be process container (molten iron boiler), and 3 be molten iron, and 4 be impeller, and 5 be the rotary shaft of impeller, and 6 be to be arranged on the blade of impeller
Gas ejection hole.
Mechanical agitation type desulfurizer has dipping, is buried in the iron being housed in the process container 2 being mounted on trolley 1
In water 3 and rotated and be used to stir the impeller 4 of the refractory material of molten iron 3.The impeller 4 using lifting device (not schemed
Show) it substantially goes up and down in vertical direction and by rotating device (not shown) in such a way that rotary shaft 5 pivots about
It constitutes.Impeller 4 is arranged by constituting from the radial multiple blades outstanding of rotary shaft 5 in the rotational circle side side of the blade
Gas ejection hole 6.That is, being opened on the front end face of radial blade outstanding with gas ejection hole 6, making inert gas via gas
Body squit hole 6 is constituted along the mode of the direction injection perpendicular to rotary shaft 5.
Gas ejection hole 6 is provided at least one on the arbitrary blade of impeller.That is, gas ejection hole 6 is in every 1 leaf
1 or more is provided on wheel.It constitutes as follows: being internally provided with the gas being connected to gas ejection hole 6 in rotary shaft 5
Supply pipe (not shown), from the inert gas that the top of rotary shaft 5 supplies from the gas supply pipe of the inside of rotary shaft 5 by
The gas ejection hole 6 being arranged on blade is reached, is blown into molten iron 3 from the front end of gas ejection hole 6, molten iron 3 is carried out
Stirring.
From the viewpoint of the floating upper and separation for promoting desulfurizing agent, the gas of setting 2 or more preferably on every 1 impeller
Squit hole 6.In addition, preferably changing gas ejection hole in the case where 2 or more gas ejection hole 6 are arranged on every 1 impeller
Vertical direction height and position.Specifically, it is preferable that the height distance of the vertical direction of any 2 gas ejection holes is set
For 100mm or more.
In the floating upper-separation process of desulfurization slag, impeller can be made to rotate, impeller can not also be made to rotate, any one side
Formula.But by rotating impeller, inert gas is dispersed in process container from the position that the blade of impeller sprays,
To promote floating for desulfurization slag, therefore preferably rotate impeller.
In the case where rotating impeller, the shape for the vortex that the rotation that preferably control passes through impeller is formed.That is, it is preferred that adjusting
The setting position of impeller and/or the revolving speed of impeller are saved, so that from the standby fluid level of the molten iron in process container to passing through impeller
The distance for rotating the recess of the vortex core formed is smaller than from above-mentioned standby fluid level to the distance of impeller upper end.
This is because the vortex core formed when the standby fluid level from the molten iron in process container to the rotation by impeller
Recess distance than it is big to the distance of impeller upper end from above-mentioned standby fluid level when, it is floating up to molten iron bath face using inert gas
Desulfurization slag is possible to be involved in molten iron again, makes to be suspended in the fine desulfurization slag in molten iron instead and increases.
In desulfurization process, in order to which the mixing power using impeller is involved in CaO fimily desulfurizing agent in molten iron, usually so that from above-mentioned
Standby fluid level to vortex core recess distance than adjusting leaf from above-mentioned standby fluid level to the big mode of the distance of impeller upper end
The revolving speed of the setting position of wheel and/or impeller is implemented (referring for example to Fig. 1 and Fig. 2 of patent document 4).But in desulfurization slag
In floating upper-separation process, in order to promote floating for desulfurization slag, the position for being set to opposite with desulfurization process preferably as described above is closed
System.
In this case, in the floating upper-separation process of desulfurization slag, it can confirm that the recess of vortex core is deep by naked eyes
It spends smaller than the impregnating depth of impeller upper end position.In addition, present inventors have proposed: the cup depth of vortex core can be by impeller
Shape, the shape of process container and impeller the stirring conditions such as revolving speed calculate (referring to Japanese Patent No. 4998676).It can also
Confirm that the cup depth of vortex core is smaller than the impregnating depth of impeller upper end position to use the calculation method.
It is shown in Fig. 2 when being stirred using impeller to molten iron in mechanical agitation type desulfurizer and form vortex
Summary.In Fig. 2,2 be process container (molten iron boiler), and 3 be molten iron, and 4 be the impeller with multiple blades, and 5 be the rotation of impeller
Axis, 7 be the standby fluid level of molten iron, and H is the cup depth of vortex core, and h is impeller upper end position (upper surface location of blade)
Impregnating depth.Fig. 2 shows make rotating diameter d, be highly b, the impeller 4 that the inclination angle of blade is θ is impregnated in and is received
The mode that molten iron 3 is stirred in the molten iron 3 in the process container 2 that internal diameter is D.Wherein, the standby fluid level 7 of molten iron 3
Liquid level when to be immersed in impeller 4 in molten iron 3.The vortex centered on the rotary shaft 5 of impeller 4 is formed in molten iron 3,
The cup depth (H) of the vortex core is analyzed with the distance away from standby fluid level 7, also, the dipping of impeller upper end position
Depth (h) is analyzed with distance away from standby fluid level 7.
Using the water model test device of mechanical agitation type desulfurizer, the vortex core under various stirring conditions is measured
Cup depth (H), using the revolving speed of impeller, the internal diameter (D) of process container, the rotating diameter (d) of impeller, impeller height (b),
Inclination angle (θ) of the blade of impeller etc. finds out the cup depth (H) of vortex core by calculating formula.As a result, it has been found that vortex core
Cup depth (H) can be calculated by using following formula (1)~formula (4).Wherein, in formula (1)~formula (4), H is vortex
The cup depth (m) at center, N are the revolving speed (beat/min) of impeller, and D is the internal diameter (m) of process container, and θ is the blade of impeller
Inclination angle (rad), b are the height (m) of impeller, and d is the rotating diameter (m) of impeller, npFor the blade the piece number of impeller, g is gravity
Acceleration (=9.8m/s2), Re is Reynolds number (zero dimension), and ρ is the density (kg/m of molten iron3), μ is the viscosity (Pa of molten iron
s)。
The vortex core away from standby fluid level 7 calculated obtained in being tested in the water model using formula (1)~formula (4)
The measured value of the cup depth (H) of the vortex core away from standby fluid level 7 in cup depth (H) and molten iron 3 in real machine into
Row compares.As a result confirmed: the two is consistent well, in the stirring using the molten iron 3 of impeller 4, even if not practical measurement,
Above-mentioned formula can be used to estimate the cup depth (H) of vortex core.In addition, it is thus identified that: even if changing process container or leaf
When the size of wheel, the treating capacity of molten iron, the impregnating depth (h) of impeller upper end position, also available identical result.
It should be noted that having cross section is the process container of ellipse, and is also had transversal for process container
Face is round but side widened process container upward.In this case, it when cross section is ellipse, can incite somebody to action
The internal diameter (D) of process container is set as the average value of major diameter and minor axis, can be by process container when side expands upward
Internal diameter (D) be set as the range contacted with molten iron internal diameter average value.In addition, impeller has upper end diameter and lower end diameter not
Same impeller.In such a case, it is possible to which the rotating diameter (d) of impeller is set as being averaged for upper end diameter and lower end diameter
Value.
That is, the present inventor confirmed: the cup depth (H) such as above-mentioned formula (1) of the vortex core on the basis of standby fluid level 7
Shown in~formula (4), the physics value etc. by the size of process container, the treating capacity of molten iron, the shape of impeller and revolving speed, molten iron is unique
Ground determines.It should be noted that the impregnating depth (h) of impeller upper end position by the base position away from impeller 4 dropping distance and
Molten iron bath face position when impeller 4 buries calculates.
Therefore, in the present invention, the desulfurization slag after desulfurization process it is floating upper-separation process in, preferably using formula (1)~
To molten iron 3 under conditions of the cup depth (H) for the vortex core that formula (4) calculates is smaller than the impregnating depth (h) of impeller upper end position
It is stirred.In such a situation it is preferred to be set as impregnating depth of the cup depth (H) than impeller upper end position of vortex core
(h) condition of small 100mm or more.It should be noted that in desulfurization process, preferably in the rotation calculated using formula (1)~formula (4)
Molten iron 3 is stirred under conditions of the cup depth (H) at whirlpool center is bigger than the impregnating depth (h) of impeller upper end position.
Cup depth (H) in order to the meet vortex core condition smaller than the impregnating depth (h) of impeller upper end position, by formula
(1)~formula (4) can clearly be learnt, the revolving speed (N) of impeller is reduced.In formula (1)~formula (4), as long as not exception processes
Container and impeller can not then change other conditions.In addition, even if identical when the cup depth (H) of vortex core is with desulfurization process,
Decline impeller and when keeping the impregnating depth (h) of impeller upper end position bigger than the cup depth of vortex core (H), can also be into
Floating upper-the separation process of the desulfurization slag of row target.
Therefore, in the present invention, the impregnating depth (h) of impeller upper end position is made to increase and/or drop the revolving speed (N) of impeller
It is low, implement the floating upper-separation process of desulfurization slag.Carry out the desulfurization slag it is floating upper-separation process when, can be according in desulfurization process
Stirring temporarily stops the rotation of impeller, then, deepens the dipping position of impeller and/or revolves impeller with low speed again
Turn.Alternatively, it is also possible to reduce the revolving speed of impeller, or the revolving speed of reduction impeller, reaching according to the stirring in desulfurization process
After scheduled revolving speed, deepen the dipping position of impeller.
In this case, in order not to interfering the desulfurization slag carried out using the inert gas that sprays from gas ejection hole 6
On floating, the flow velocity of the molten iron in aspiration level direction is smaller, it is therefore preferable that reducing the revolving speed of impeller.But when the rotation for making impeller
When stopping, the ejection position of inert gas can become the constant position in process container, therefore preferably stop the rotation of impeller
Only.
By by the desulfurization slag being suspended in molten iron or the desulfurization slag being attached on process container inner wall from process container
It removes, the desulfurization slag of the dephosphorization treatment process and Decarburising and refining process that are brought to subsequent processing is reduced, dephosphorization treatment process, decarburization
The sulphur that returns in refining procedure is inhibited.
As the inert gas being blown into from the gas ejection hole of impeller, the rare gas such as argon gas, nitrogen can be used.At this
In the case of kind, the flow that is blown into of inert gas is preferably set to 0.010Nm3/ (minute molten iron-ton) or more.This is because
Flow is blown into less than 0.010Nm in inert gas3When/(minute molten iron-ton), mixing power is weak, can not make to be suspended in molten iron
In desulfurization slag, the desulfurization slag that is attached on process container inner wall fully float, inhibit back sulphur with being unable to fully.Inert gas
The upper limit value for being blown into flow do not need special provision, even if being blown into large quantities, return the effect that prevents of sulphur and be also saturated, do not have
Further prevent back the effect of sulphur, on the contrary, it is excessive be blown into flow can due to the generation of splash, the reduction of molten iron temperature and hamper
Hinder operation.Therefore, upper limit value is in 0.10Nm3The left and right/(minute molten iron-ton).
In addition, the longer the blowing time of inert gas the more effective, but be blown into the extension that will lead to the processing time for a long time,
It is therefore preferable that being set as 30 seconds or more and 3 minutes or less.At 30 seconds or more and 3 minutes or less, available sufficient effect
Fruit.
The desulfurization process of molten iron is implemented as follows: using the mechanical agitation type desulfurizer of composition shown in Fig. 1, impeller being impregnated
In the molten iron in the process container for being housed in molten iron pouch-type, the impeller is rotated, molten iron and CaO fimily desulfurizing agent are stirred
It mixes.
As the method that is removed from process container of desulfurization slag that will forcibly be floated by the stirring using inert gas,
The following method can be used.It is, for example, possible to use: so that process container is tilted to degree that molten iron will not flow out, using slagging-off
The method that machine etc. is mechanically drawn；Or attracted using vacuum type deslagging device and the method that removes；Deng.It is being discharged
After desulfurization slag, the reduction of molten iron temperature, preferably adds heat preserving agent in process container in order to prevent.
It should be noted that used molten iron is that can also implement desulfurization using the molten iron after blast furnace, shaft furnace melting
Implement desiliconization processing, dephosphorization treatment before processing.In the case where implementing the molten iron of dephosphorization treatment in advance, subsequent processing is benefit
It therefore will forcibly be floated from removing in process container by the stirring using inert gas with the Decarburising and refining process of converter
Desulfurization slag after molten iron be transported to carry out Decarburising and refining converter.On the other hand, implement the dephosphorization of molten iron after desulfurization process
As in pretreated situation, subsequent processing is dephosphorization treatment process for processing, therefore, will be removed from process container lazy by utilizing
Property gas stirring forcibly float on desulfurization slag after molten iron be transported to implement dephosphorization treatment equipment.
As discussed above, according to the present invention, make to remain in process container by the stirring using inert gas
Interior desulfurization slag forces that the desulfurization slag floated up is discharged from process container, then, molten iron is supplied to subsequent processing on floating
Dephosphorization treatment, Decarburising and refining.As a result, leading to back the major part of the desulfurization slag of sulphur when implementing dephosphorization treatment, Decarburising and refining
It is removed, reduces dephosphorization treatment, returns sulphur in Decarburising and refining.
Embodiment
It is 0.0024 mass % low-sulfur steel below according to desulfurization process, dephosphorization treatment by the sulphur concentration specification of steel part
When sequence carries out melting, tested as follows: existing smelting process and the present invention for implementing each 150 chargings (charge) respectively are molten
Refining method compares the Sulfur Content in Hot Iron concentration at the end of the dephosphorization treatment of subsequent processing.If the Sulfur Content in Hot Iron at the end of dephosphorization treatment is dense
Degree generates difference, then this is as returning caused by sulfur content difference.
Herein, existing smelting process refers to following method of smelting: the desulfurization of CaO system is utilized in mechanical agitation type desulfurizer
After agent carries out desulfurization process, without the floating upper-separation process of desulfurization slag, the desulfurization slag for covering molten iron bath face is removed, is being removed
Carry out melting low-sulfur steel via the dephosphorization treatment process of subsequent processing and Decarburising and refining process at once after desulfurization slag.In addition, of the invention
Smelting process refers to following method of smelting: after carrying out desulfurization process using CaO fimily desulfurizing agent in mechanical agitation type desulfurizer,
Floating upper-the separation process of desulfurization slag is carried out by being blown into inert gas from the gas ejection hole that impeller is arranged in, in the desulfurization slag
The desulfurization slag that covering molten iron bath face is removed after floating upper-separation process, then, via the dephosphorization treatment process of subsequent processing and decarburization
Refining procedure carrys out melting low-sulfur steel.
In specific test method, CaO-CaF is used2Desulfurizing agent is filled as CaO fimily desulfurizing agent in mechanical agitation type desulfurization
The desulfurization process for carrying out the molten iron in molten iron boiler is set, the sulphur concentration of molten iron is made to be reduced to 0.0010 mass % or less.At desulfurization
The sulphur concentration of molten iron after reason is 0.0006 mass %.Used 4 kinds of impeller As, B, C, D be rotating diameter (d) be 1.4m,
The height (b) of impeller is 0.8m, has 4 blades and blade does not have the impeller of tilt angle (θ=pi/2).
Impeller A is the impeller for having 1 gas ejection hole in the rotational circle side side of 1 blade.Impeller B, C are right
The rotational circle side side of 2 blades on linea angulata is respectively provided with the impeller of 1 gas ejection hole.2 gases of impeller B spray
The identical height and position of vertical direction is arranged in hole, and the different height position of vertical direction is arranged in 2 gas ejection holes of impeller C
It sets.The vertically position at a distance of 100mm is arranged in 2 gas ejection holes of impeller C.Impeller D is in existing smelting process
The impeller without gas ejection hole used.
Chemical component before the desulfurization process of used molten iron is mass %, Si:0.1 of C:3.5~5.0~0.3 matter
Measure mass %, P:0.10 of %, S:0.025~0.035~0.15 mass %, the range that molten iron temperature is 1250~1350 DEG C.It is de-
In sulphuring treatment, use can store 250~350 tons molten iron molten iron boiler (internal diameter D=3.9m) as process container, process object
Iron water amount be set as about 300 tons.The specific consumption of used desulfurizing agent is set as 5.0~7.5kg/ molten iron-ton.
It in existing smelting process, successively carries out: carrying out desulfurization process using impeller D and the desulfurization slag of molten iron bath face will be covered
The desulfurization slag deslagging process that is removed from molten iron boiler, by molten iron from molten iron boiler be packed into be packed into the process of pot, by molten iron from loading
To loading pot tapping after pot is fitted into the process of converter, carries out molten iron in converter the process of dephosphorization treatment, dephosphorization treatment
Dephosphorized slag after tapping is packed into from pot is packed into the process of converter, in converter by process from the process of loading pot removing, by molten iron
The process of the middle Decarburising and refining for carrying out molten iron.
In addition, successively being carried out in smelting process of the present invention: carrying out desulfurization process using impeller A, B, C and in desulfurization process
Floated afterwards by the way that the desulfurization slag that each gas ejection hole of impeller A, B, C is blown into inert gas to carry out is arranged in-separation process,
It is packed into from molten iron boiler to the work for being packed into pot by desulfurization slag deslagging process that the desulfurization slag floated up is removed from molten iron boiler, by molten iron
Sequence, by molten iron after being fitted into the process of dephosphorization treatment, dephosphorization treatment that pot is fitted into the process of converter, carries out molten iron in converter
Converter is packed into from pot is packed into from the process of loading pot removing, by molten iron to the process of loading pot tapping, by the dephosphorized slag after tapping
Process, in converter carry out molten iron Decarburising and refining process.
In existing smelting process and smelting process of the present invention, increase not adding the sulfur content for leading to molten iron in dephosphorization treatment
Auxiliary material in the case where carry out dephosphorization treatment.By desulfurization slag after the desulfurization slag deslagging process removed in molten iron boiler and dephosphorization
After processing from molten iron collection analysis sample, the sulphur concentration of assay sample is analyzed.
The average value for returning sulfur content in existing smelting process and smelting process of the present invention is shown in table 1.It returns sulfur content and is set as de-
The difference of Sulfur Content in Hot Iron concentration after Sulfur Content in Hot Iron concentration and desulfurization slag deslagging process of the phosphorus when processing terminate.It confirmed: later
Decarburising and refining after, return sulfur content be zero.It should be noted that smelting process of the present invention shown in table 1 is using impeller A, de-
30 seconds 0.10Nm are blown into the floating upper-separation process of sulphur slag3The data when argon gas of/(minute molten iron-ton).
[table 1]
In existing smelting process, sulphur concentration rises because returning sulphur in molten steel, returns sulfur content with the flat of 150 chargings after testing
It is calculated as 0.0052 mass %.In contrast, in smelting process of the present invention, returning sulfur content is 0.0007 matter of mass %~0.0015
%, 0.0011 mass % of average out to are measured, is significantly reduced.
In existing smelting process, there are the sulphur concentration when converter tapping of subsequent handling be more than specification value charging, from
After converter tapping, need to implement desulfurizing and refining to the molten steel in ladle in ladle refining equipment (LF equipment).But
In smelting process of the present invention, it may validate that in all chargings, it can be by sulphur concentration control in the molten steel after Decarburising and refining low
The 0.0024 mass % or less of the specification value of sulphur steel grade.Therefore, the iron in smelting process of the present invention, after can be completely omitted tapping
Desulfurizing and refining in water packet refining equipment (LF equipment).
In addition, being tested: being held to from processing as follows in the floating upper-separation process of desulfurization slag in smelting process of the present invention
The standby fluid level of molten iron in device to the impeller by being immersed in the molten iron rotation formed vortex core recess away from
From (H) at a distance from until from above-mentioned standby fluid level to impeller upper end the relationship of (h) give back to sulfur content bring influence investigated.
Specifically, with the progress of the following two kinds method: [1] does not change the setting of the vertical direction of impeller after desulfurization process
Position (distance (h) is constant), the case where reducing the revolving speed of impeller and change distance (H)；And [2] make impeller after desulfurization process
The setting position of vertical direction change (distance (h) become larger) downwards, and reduce the revolving speed of impeller and change distance (H)
Situation.In this case, distance (H) is calculated using formula (1)~formula (4).Used impeller be impeller A, B, C, in order to
It is compared, also uses impeller D.
In smelting process of the present invention, it is blown into 30 seconds 0.10Nm3The argon gas of/(minute molten iron-ton) is implemented at desulfurization
Floating upper-the separation process of desulfurization slag after reason.In the existing smelting process using impeller D, it is not blown into argon gas after desulfurization process, changes
Become the revolving speed of impeller and change distance (H), is kept for 30 seconds in this state.
Each treatment conditions are shown in table 2 and return sulfur content.
[table 2]
In the Comparative Examples 1 and 2 of existing smelting process, and though distance (H) and (h) relationship, Sulfur Content in Hot Iron concentration all because
It returns sulphur and rises, returning sulfur content is respectively 0.0052 mass %, 0.0050 mass %.
In contrast, in example 1~6 of the present invention, return sulfur content be 0.0005~0.0015 mass %, be reduced to comparative example 1,
2 less than half for returning sulfur content.
Especially in distance (H) the of the present invention example 2,4,6 smaller than distance (h), returning sulfur content is 0.0005~0.0010 matter
% is measured, below time sulfur content of 0.0010 mass % is realized, the of the present invention example 1,3,5 bigger than distance (h) returns sulphur with distance (H)
Amount (0.0010~0.0015 mass %) is compared, and sulfur content can be greatly reduced back.I.e., it is possible to confirm: by make distance (H) than away from
Small from (h), returning sulfur content reduces.
In addition, when being compared to impeller A, B, C, in the example of the present invention 2,4,6 of distance (H) condition smaller than distance (h)
In, time sulfur content is equal in impeller A (example 2 of the present invention) and impeller B (example 4 of the present invention), in contrast, in impeller C (example of the present invention
6) sulfur content is returned in be greatly reduced.
I.e., it is possible to confirm: by the rotational circle side side of 2 blades on the diagonal, in the difference of vertical direction
1 gas ejection hole is respectively set in height and position, can especially reduce back sulfur content.
Symbol description
1 trolley
2 process containers
3 molten iron
4 impellers
5 rotary shafts
6 gas ejection holes
7 standby fluid levels
Claims (4)
1. a kind of time sulphur prevention method of the molten iron after desulfurization process, wherein
Desulfurization process is implemented to the molten iron in process container using mechanical agitation type desulfurizer,
Then, it is blown into from the gas ejection hole on the impeller that the mechanical agitation type desulfurizer is arranged in into the molten iron lazy
Property gas is stirred molten iron, makes the desulfurization slag being suspended in molten iron by the stirring and/or is attached in process container
Desulfurization slag on wall is floating up to molten iron bath face, the gas ejection hole in the rotational circle side side of the blade of impeller,
The desulfurization slag floated up is discharged from process container,
Then, the molten iron in process container is transported to subsequent processing.
2. time sulphur prevention method of the molten iron after desulfurization process as described in claim 1, wherein in the gas ejection hole
Position rotates the impeller in the state of being impregnated in molten iron, adjusts the setting position of impeller and/or the revolving speed of impeller, so that from
In the vortex that the rotation of the standby fluid level of molten iron in the process container to the impeller by being impregnated in the molten iron is formed
The distance of the recess of the heart is smaller than from the standby fluid level to the distance of impeller upper end.
3. molten iron after desulfurization process as claimed in claim 2 returns sulphur prevention method, wherein by following formulas (1)~
Formula (4) calculates the distance of the recess from the standby fluid level to vortex core,
Wherein, in these formulas, H is the distance (m) of the recess from the standby fluid level of molten iron to vortex core, and N is turning for impeller
Fast (beat/min), D are the internal diameter (m) of process container, and θ is the inclination angle (rad) of the blade of impeller, and b is the height (m) of impeller,
D is the rotating diameter (m) of impeller, npFor the blade the piece number of impeller, g is acceleration of gravity, that is, 9.8m/s2, Re is zero dimension Reynolds
Number, ρ are the density (kg/m of molten iron3), μ is the viscosity (Pas) of molten iron.
4. time sulphur prevention method of the molten iron after desulfurization process according to any one of claims 1 to 3, wherein the gas
Two or more is arranged in body squit hole on each impeller, is configured with changing the height and position of vertical direction.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014002806 | 2014-01-10 | ||
| JP2014-002806 | 2014-01-10 | ||
| PCT/JP2015/000001 WO2015105035A1 (en) | 2014-01-10 | 2015-01-05 | Method for preventing resulfurization of molten pig iron after desulfurization |
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| Publication Number | Publication Date |
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| CN105899689A CN105899689A (en) | 2016-08-24 |
| CN105899689B true CN105899689B (en) | 2019-05-07 |
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| CN201580004067.5A Expired - Fee Related CN105899689B (en) | 2014-01-10 | 2015-01-05 | Time sulphur prevention method of molten iron after desulfurization process |
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| Country | Link |
|---|---|
| JP (1) | JP6052436B2 (en) |
| KR (1) | KR101840962B1 (en) |
| CN (1) | CN105899689B (en) |
| BR (1) | BR112015009665A2 (en) |
| TW (1) | TWI564396B (en) |
| WO (1) | WO2015105035A1 (en) |
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|---|---|---|---|---|
| CN103014218A (en) * | 2012-12-30 | 2013-04-03 | 大冶特殊钢股份有限公司 | KR stirring paddle and manufacture method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5285013A (en) | 1976-01-09 | 1977-07-15 | Kawasaki Steel Co | Method and apparatus for desulphorizing of molten pig iron |
| JPH0499212A (en) * | 1990-08-08 | 1992-03-31 | Sumitomo Metal Ind Ltd | Apparatus for desulfurizing molten iron |
| JPH04235210A (en) | 1991-01-10 | 1992-08-24 | Sumitomo Metal Ind Ltd | Method for desulfurizing molten iron |
| JP2856106B2 (en) | 1995-03-30 | 1999-02-10 | 住友金属工業株式会社 | Hot metal desulfurization method |
| JP2001247910A (en) * | 2000-03-03 | 2001-09-14 | Nippon Steel Corp | Method for stirring molten iron |
| JP3835350B2 (en) * | 2002-05-30 | 2006-10-18 | Ｊｆｅスチール株式会社 | Rotating stirrer for molten metal |
| JP2005200762A (en) | 2003-12-16 | 2005-07-28 | Sumitomo Metal Ind Ltd | Method for desulfurizing molten pig iron |
| JP2006028615A (en) * | 2004-07-20 | 2006-02-02 | Sumitomo Metal Ind Ltd | Method for desulfurizing molten pig iron, and mechanically stirring device |
| JP4998676B2 (en) * | 2006-03-29 | 2012-08-15 | Ｊｆｅスチール株式会社 | Method of stirring molten metal using impeller |
| JP6024192B2 (en) * | 2012-05-15 | 2016-11-09 | Ｊｆｅスチール株式会社 | Method for preventing hot metal after desulphurization |
-
2015
- 2015-01-05 KR KR1020167021363A patent/KR101840962B1/en active IP Right Grant
- 2015-01-05 CN CN201580004067.5A patent/CN105899689B/en not_active Expired - Fee Related
- 2015-01-05 WO PCT/JP2015/000001 patent/WO2015105035A1/en active Application Filing
- 2015-01-05 JP JP2015556780A patent/JP6052436B2/en active Active
- 2015-01-05 BR BR112015009665A patent/BR112015009665A2/en not_active Application Discontinuation
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| CN103014218A (en) * | 2012-12-30 | 2013-04-03 | 大冶特殊钢股份有限公司 | KR stirring paddle and manufacture method thereof |
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| WO2015105035A1 (en) | 2015-07-16 |
| TW201540842A (en) | 2015-11-01 |
| JPWO2015105035A1 (en) | 2017-03-23 |
| BR112015009665A2 (en) | 2017-07-04 |
| JP6052436B2 (en) | 2016-12-27 |
| TWI564396B (en) | 2017-01-01 |
| KR20160106130A (en) | 2016-09-09 |
| KR101840962B1 (en) | 2018-03-21 |
| CN105899689A (en) | 2016-08-24 |
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