CN114657306A - Stirring head and method for promoting graphite precipitation in molten iron pretreatment - Google Patents
Stirring head and method for promoting graphite precipitation in molten iron pretreatment Download PDFInfo
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- CN114657306A CN114657306A CN202210339754.4A CN202210339754A CN114657306A CN 114657306 A CN114657306 A CN 114657306A CN 202210339754 A CN202210339754 A CN 202210339754A CN 114657306 A CN114657306 A CN 114657306A
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- molten iron
- stirring head
- head body
- stirring
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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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention relates to the technical field of molten iron pretreatment, in particular to a stirring head and a method for promoting graphite precipitation in molten iron pretreatment. According to the invention, the blowing gas is sprayed into the ladle through the bottom of the stirring head, the molten iron flow field and the temperature gradient in the ladle are optimized, the contact interface between the solvent and the molten iron is increased, the reaction efficiency and the desulfurization effect of the desulfurizing agent are improved, the precipitation condition of saturated carbon in the molten iron is improved, and the graphite precipitation efficiency and effect in the molten iron pretreatment process are promoted.
Description
Technical Field
The invention relates to the technical field of molten iron pretreatment, in particular to a stirring head and a method for promoting graphite precipitation in molten iron pretreatment.
Background
The pretreatment of molten iron has important significance in modern steelmaking and is an indispensable link in the optimized production process flow of steelmaking. At present, two forms of a blowing method and a KR method are common, wherein the KR method has the advantages of good metallurgical dynamic condition, stable effect, low operation cost, high efficiency and the like, and is widely popularized and applied at home and abroad.
KR (Kambarareactor) mechanical stirring method is that a cross-shaped stirring head which is poured with refractory material and is baked is immersed into a molten iron ladle melting pool for a certain depth, a weighed desulfurizer is added to the surface of molten iron by a feeder by virtue of a vortex generated by rotation of the cross-shaped stirring head, and the weighed desulfurizer is involved into the molten iron by the vortex to ensure that calcium oxide based desulfurization powder and the molten iron are in full contact reaction, thereby achieving the aim of desulfurization. When the stirrer rotates, the molten iron liquid level forms a V-shaped vortex (low center and high periphery), and after the desulfurizer is added, flux particles are dispersed in the end area of the blade due to turbulence and are 'spit out' along the radius direction, then suspended, rotated around the axis and float in the molten iron, that is, the flux is involved in the molten iron by the mechanical stirring action, contacted with the molten iron, mixed and stirred, so that the desulfurization reaction is carried out. Its advantages are excellent dynamic condition, low cost of desulfurizing agent (CaO), high desulfurizing effect (less than or equal to 0.005%), low consumption of desulfurizing agent, and high effect on desulfurizing low-sulfur steel. But the equipment is complex, the one-time investment is large, and the temperature drop of the desulfurized molten iron is large.
Graphite is a strategic mineral resource with wide application, and a large amount of flake graphite can be produced as a byproduct in the production process of the ferrous metallurgy industry. In the process of blast furnace tapping, molten iron transferring and molten iron pretreatment, the carbon element in the molten iron is supersaturated due to the change of molten iron temperature thermal history and relevant physical kinetic energy conditions, so that the aggregated crystalline flake graphite is separated out, and the aggregated crystalline flake graphite has the same performance as natural crystalline flake graphite after being collected and purified.
The supersaturation of molten iron carbon is a necessary condition for graphite precipitation, and the temperature and the change of the molten iron carbon solubility present a better linear relation. The carbon content in the steelmaking iron water is about 4.4%, and supersaturated carbon in iron can be aggregated and separated out in a scale form along with the reduction of temperature and proper stirring kinetic energy in the process of pretreating the molten iron KR. For a long period of time, these precipitated graphite are mixed with slag, ash, etc., and have been considered as waste materials and ignored. The prior KR pretreatment process for the molten iron lacks reasonable control and optimization of temperature gradient and stirring kinetic energy of the molten iron, has low efficiency (about 2-3%) of saturated precipitation of carbon in the molten iron, influences effective precipitation of graphite, and rarely recovers the graphite to cause waste of graphite resources.
Disclosure of Invention
Aiming at the problem of low graphite precipitation rate in molten iron pretreatment in the prior art, the invention provides the stirring head and the method for promoting graphite precipitation in molten iron pretreatment, and the speed and the effect of graphite precipitation in the KR pretreatment process of molten iron are improved.
In a first aspect, the invention provides a stirring head for promoting graphite precipitation in molten iron pretreatment, which comprises a cross-shaped stirring head body, wherein a connecting shaft is fixed on the upper end face of the stirring head body, a main hole penetrating through the connecting shaft and the stirring head body is arranged in the axial direction of the connecting shaft, four side holes are arranged in the stirring head body, one end of each side hole is communicated with the main hole, and the other end of each side hole is positioned on the lower end face of the stirring head body.
Furthermore, on the lower end face of the stirring head body, four side holes are uniformly distributed on the same concentric circle by taking the main hole as the circle center.
In a second aspect, the present invention provides a method for promoting graphite precipitation in molten iron pretreatment, comprising the following steps:
s1, blowing gas is injected into a main hole of the stirring head connecting shaft, and the connecting shaft is fixed with a rotating shaft of a stirring motor;
s2, before the pretreatment of the molten iron begins, opening an injection valve of the blowing gas, starting a stirring motor, wherein the stirring speed is r1The stirring head body descends into molten iron;
s3, adding a desulfurizing agent into the molten iron, and continuously stirring by the stirring head body at the stirring speed r2；
S4, after the molten iron is pretreated, lifting the stirring head body to a maintenance position, and closing the blowing gas inlet valve.
Further, in step S1, the blowing gas is nitrogen.
Further, in step S2, the pressure of nitrogen is 0.4MPa and the flow rate of nitrogen is 100-120 Nm3/min。
Further, in step S2, r140-50 r/min.
Further, in step S2, the blowing gas is ejected from the lower end face of the stirring head body to locally cool the molten iron, the cooling rate of the molten iron close to the lower end face of the stirring head body is 1.5 ℃/min, the molten iron is cooled to 1280-1300 ℃, and under the condition, the blown nitrogen locally cools the molten iron, so that the optimal condition for precipitation of saturated carbon in the molten iron is met, and the precipitation of graphite is accelerated under the action of a rotating molten iron flow field.
Further, in step S3, r2100-120 r/min.
The principle of the invention is that KR stirring is mainly used for improving the dynamic condition of chemical reaction in the molten iron desulphurization process, so that molten iron and a desulfurizer can be fully and effectively contacted, and the opportunity of mutual reaction is increased. According to the invention, the main hole and the side hole which can be introduced with the blowing gas are arranged in the connecting shaft of the stirring head, and the blowing gas is sprayed out from the lower end surface of the stirring head body, so that the contact area and the reaction interface between the desulfurizer and the molten iron are further increased, the flow field of the molten iron is improved, the temperature gradient is optimized, more favorable conditions are created for the precipitation of saturated carbon in the molten iron, and the rate and the effect of graphite precipitation in the KR pretreatment process of the molten iron are obviously improved.
The invention has the beneficial effects that the blowing gas is sprayed into the ladle through the bottom of the stirring head, the molten iron flow field and the temperature gradient in the ladle are optimized, the contact interface of the solvent and the molten iron is increased, the reaction efficiency and the desulfurization effect of the desulfurizer are improved, the precipitation condition of saturated carbon in the molten iron is improved, and the graphite precipitation efficiency and effect in the molten iron pretreatment process are promoted.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
Fig. 1 is a schematic perspective view of a stirring head in embodiment 1 of the present invention.
Fig. 2 is a bottom view of fig. 1 in accordance with an embodiment of the present invention.
Fig. 3 is a cross-sectional view taken along the longitudinal centerline of fig. 1 in accordance with an embodiment of the present invention.
In the figure: 1-main hole, 2-connecting shaft, 3-stirring head body and 4-side hole.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
As shown in fig. 1 to 3, the stirring head for promoting graphite precipitation in molten iron pretreatment according to the present invention includes a cross-shaped stirring head body 3, a connecting shaft 2 is fixed on an upper end surface of the stirring head body 3, a main hole 1 penetrating the connecting shaft 2 and the stirring head body 3 is axially provided in the connecting shaft 2, four side holes 4 are provided in the stirring head body 3, one end of each side hole 4 is communicated with the main hole 1, the other end of each side hole 4 is located on a lower end surface of the stirring head body 3, and the four side holes 4 are uniformly distributed on the same concentric circle with the main hole 1 as a center of circle on the lower end surface of the stirring head body 3.
When the stirring head is used, the connecting shaft 2 is connected with the rotating shaft of the stirring motor, and a ventilation rotating structure such as a ventilation rotating joint in the prior art can be adopted during connection, and the ventilation rotating structure is connected with a nitrogen tank for ventilation in the main hole.
Example 2
The method for promoting graphite precipitation in the molten iron pretreatment comprises the following steps:
the temperature of the molten iron is 1362 ℃, the weight of the molten iron is 125 tons, the ladle car is turned to a treatment position, a nitrogen valve (the pressure is 0.4MPa, the flow is 110 Nm)3Min), the stirring head starts to rotate (the rotating speed is 50 revolutions per minute) and descends to the position required by the process; adding 500kg of desulfurizer, stirring for 9min (the rotating speed of a stirring head is 105 r/min), blowing nitrogen from the bottom of the stirring head, cooling the molten iron close to the lower end face of the stirring head to 1300 ℃ at a cooling rate of 1.5 ℃/min, and promoting graphite precipitation; after the pretreatment and stirring are finished, the stirring head is lifted to the maintenance position, and the nitrogen valve is closed.
The measured molten iron temperature in the embodiment is 1316 ℃, the total carbon content separated out from the flue gas dust and the desulphurization slag is 4.52%, and the carbon content is improved by 51-126% compared with the traditional process.
Example 3
The method for promoting graphite precipitation in the molten iron pretreatment comprises the following steps:
the temperature of the molten iron is 1336 ℃, the weight of the molten iron is 125 tons, the molten iron is turned to a processing position by a ladle car, and the molten iron is beatenOpen nitrogen valve (pressure 0.4MPa, flow 110 Nm)3Min), the stirring head starts to rotate (the rotating speed is 40 revolutions per minute) and descends to the position required by the process; adding 600kg of desulfurizer, stirring for 8min (the rotating speed of a stirring head is 110 r/min), blowing nitrogen from the bottom of the stirring head, cooling the molten iron close to the lower end face of the stirring head at the speed of 1.5 ℃/min to 1290 ℃, and promoting graphite precipitation; after the pretreatment and stirring are finished, the stirring head is lifted to the maintenance position, and the nitrogen valve is closed.
The temperature of the molten iron is measured to be 1282 ℃ after the treatment, the total carbon content separated out from the flue gas dust and the desulphurization slag is 4.81 percent, and the carbon content is improved by 60 to 140 percent compared with the traditional process.
Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention.
Claims (8)
1. The utility model provides a promote stirring head that graphite was appeared in molten iron preliminary treatment, includes cross stirring head body (3), its characterized in that is fixed with connecting axle (2) on stirring head body (3) up end, is equipped with main hole (1) that runs through connecting axle (2), stirring head body (3) in the axial of connecting axle (2), is equipped with four side openings (4) in stirring head body (3), side opening (4) one end and main hole (1) intercommunication, side opening (4) other end is located stirring head body (3) down on the terminal surface.
2. The stirring head for promoting graphite precipitation in molten iron pretreatment according to claim 1, wherein four side holes (4) are uniformly distributed on the same concentric circle with the main hole (1) as the center of the circle on the lower end surface of the stirring head body (3).
3. A method for promoting graphite precipitation in molten iron pretreatment is characterized by comprising the following steps:
s1, blowing gas is injected into the main hole (1) of the stirring head connecting shaft (2) in the claim 1, and the connecting shaft (2) is fixed with the rotating shaft of the stirring motor;
s2, before the pretreatment of the molten iron begins, opening an injection valve of the blowing gas, starting a stirring motor, wherein the stirring speed is r1The stirring head body (3) is descended into the molten iron;
s3, adding a desulfurizing agent into the molten iron, and continuously stirring the molten iron by the stirring head body (3) at the stirring speed r2；
S4, after the molten iron is pretreated, the stirring head body (3) is lifted to a maintenance position, and the blowing gas is closed to enter the valve.
4. The method for promoting graphite precipitation in molten iron pretreatment according to claim 3, wherein the blowing gas is nitrogen in step S1.
5. The method for promoting graphite precipitation in molten iron pretreatment according to claim 4, wherein in step S2, the pressure of nitrogen is 0.4MPa and the flow rate of nitrogen is 100 to 120Nm3/min。
6. The method for promoting graphite precipitation in molten iron pretreatment according to claim 3, wherein r in step S2140-50 r/min.
7. The method for promoting graphite precipitation in molten iron pretreatment according to claim 3, wherein in step S2, the blowing gas is blown out from the lower end surface of the stirring head body (3) to locally cool the molten iron, and the temperature of the molten iron near the lower end surface of the stirring head body (3) is lowered to 1280 to 1300 ℃ at a rate of 1.5 ℃/min.
8. The method for promoting graphite precipitation in molten iron pretreatment of claim 3, wherein r in step S32100-120 r/min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210339754.4A CN114657306A (en) | 2022-04-01 | 2022-04-01 | Stirring head and method for promoting graphite precipitation in molten iron pretreatment |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210339754.4A CN114657306A (en) | 2022-04-01 | 2022-04-01 | Stirring head and method for promoting graphite precipitation in molten iron pretreatment |
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| CN114657306A true CN114657306A (en) | 2022-06-24 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115216570A (en) * | 2022-07-28 | 2022-10-21 | 山东钢铁股份有限公司 | Method for improving graphite precipitation rate in molten iron |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105256102A (en) * | 2014-07-16 | 2016-01-20 | 鞍钢股份有限公司 | Blowing and stirring integrated type molten iron pretreatment desulphurization device and method |
| CN110699508A (en) * | 2019-10-31 | 2020-01-17 | 武汉科技大学 | Blowing type spiral stirrer for molten iron desulphurization |
| CN212894811U (en) * | 2020-07-22 | 2021-04-06 | 山东钢铁股份有限公司 | Device for promoting flake graphite precipitation in molten iron desulphurization process |
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2022
- 2022-04-01 CN CN202210339754.4A patent/CN114657306A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105256102A (en) * | 2014-07-16 | 2016-01-20 | 鞍钢股份有限公司 | Blowing and stirring integrated type molten iron pretreatment desulphurization device and method |
| CN110699508A (en) * | 2019-10-31 | 2020-01-17 | 武汉科技大学 | Blowing type spiral stirrer for molten iron desulphurization |
| CN212894811U (en) * | 2020-07-22 | 2021-04-06 | 山东钢铁股份有限公司 | Device for promoting flake graphite precipitation in molten iron desulphurization process |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115216570A (en) * | 2022-07-28 | 2022-10-21 | 山东钢铁股份有限公司 | Method for improving graphite precipitation rate in molten iron |
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