CN118147385A - Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch - Google Patents

Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch Download PDF

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CN118147385A
CN118147385A CN202410115932.4A CN202410115932A CN118147385A CN 118147385 A CN118147385 A CN 118147385A CN 202410115932 A CN202410115932 A CN 202410115932A CN 118147385 A CN118147385 A CN 118147385A
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powder
gas
molten iron
desulfurizing
dephosphorizing
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朱苗勇
王泽宇
娄文涛
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东北大学
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention discloses a device and a method for desulfurizing, desilicating and dephosphorizing molten iron by spraying powder at the bottom of a molten iron channel, which relate to the technical field of molten iron pretreatment in the metallurgical industry. In the tapping process of the blast furnace, desulfurization gas powder is blown into molten iron through a first bottom blowing element arranged at the bottom of a turbulent flow zone of a first molten iron channel, so as to complete pretreatment desulfurization of the molten iron; and (3) spraying mixed gas powder of desilication and dephosphorization or spraying desilication gas powder and dephosphorization gas powder respectively into the molten iron subjected to desulfurization and skimming treatment through a second bottom blowing element arranged at the bottom of the second molten iron channel, so as to finish desilication and dephosphorization of the molten iron. According to the invention, the desulfurization, desilication and dephosphorization powder enters the molten iron through the bottom blowing element arranged at the bottom of the molten iron runner, the powder directly enters the deep part of the molten iron, the powder is fully mixed with the molten iron under the combined action of carrier gas stirring and molten iron flow impact, the contact area of the powder and the molten iron is increased, the effective utilization efficiency of the desulfurization, desilication and dephosphorization agent is improved while the reaction rate is increased, and the pretreatment of the molten iron is better completed.

Description

Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch
Technical Field
The invention belongs to the technical field of molten iron pretreatment in the metallurgical industry, and particularly relates to a device and a method for desulfurizing, desilicating and dephosphorizing by spraying powder on the bottom of a molten iron channel.
Background
In recent years, with the continuous increase of market competition for iron and steel products and the increasing of production cost, particularly, due to the production requirements of high-quality low-cost steel, the molten iron pretreatment technology has been rapidly developed. Further requirements are made of the steel industry: firstly, the high-end imported steel varieties which are in shortage at home at present are actively developed, and the self-supporting rate is improved; and secondly, high-quality and high-performance steel is used for replacing middle-low grade steel, so that the energy consumption is reduced, and the service life of the product is prolonged. Therefore, the content of harmful elements in molten iron, particularly the content of sulfur and phosphorus, must be reduced, in the existing steel smelting flow, the primary dephosphorization task is born by the converter early-stage oxygen blowing smelting, the silicon element in the molten iron is oxidized in preference to the phosphorus element according to the thermodynamic selective oxidation rule, and a large amount of heat is emitted while the silicon element is oxidized, and the dephosphorization is not facilitated when the temperature is higher as the thermodynamic condition indicates; the molten iron produced in the blast furnace contains a certain amount of silicon element, and therefore, desilication is necessary on the premise of dephosphorization in the converter.
Silicon has been used as a heating element in converter steelmaking, but as the capacity of converters increases and smelting technology advances, the amount of heat provided by silicon is required to be gradually reduced. In addition, the reduction of slag quantity is very beneficial to improving the economic index of steelmaking technology, the oxide of silicon formed by the silicon element after oxidation and heat release is an acidic oxide, slag is formed together with lime, and the load of converter slag is increased, so that the molten iron to be charged into a furnace needs to have low silicon content, and the mass fraction of silicon in the molten iron needs to be lower than 0.15%. In recent years, pretreatment desilication has become an indispensable process for iron and steel enterprises, and is widely used in japan in particular. At present, the technology is also rapidly developing domestically.
Currently, there are three main methods for pre-desulfurization, desilication and dephosphorization of molten iron: a traditional blast furnace tapping channel method; spraying method in torpedo car or hot metal ladle; a "two-stage" removal process. The traditional blast furnace tapping channel method is to directly add the reaction raw materials into a blast furnace tapping channel for desilication, and has the advantages that the desilication does not occupy time, can be largely processed, has small temperature drop and short time, and is convenient for slag and iron separation; the disadvantage is low utilization of the reactants and poor reaction conditions. The injection method in the torpedo car or the hot metal ladle is characterized by good reaction conditions, large treatment capacity, high and stable removal efficiency; the disadvantage is long occupation time and large temperature drop. The two-stage removing method is the combination of the first two methods, and is to add the reaction raw materials into the molten iron runner to perform the preliminary reaction, and then to spray and remove the raw materials in the torpedo ladle car or the molten iron tank. The current hot metal pretreatment technology has more or less problems, and in this context, it is necessary to seek a new hot metal pretreatment technology.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art or related art.
To this end, according to a first aspect of the present invention, there is provided an apparatus for desulfurizing, desilicating and dephosphorizing molten iron runner bottom powder injection, comprising:
The gas storage tank is used for storing carrier gas;
The powder tank is used for storing desulfurization, desilication and dephosphorization powder;
The gas-powder mixing fluidization chamber is used for mixing and fluidizing carrier gas and desulfurization, desilication and dephosphorization powder; the gas-powder mixing fluidization chamber is respectively connected with a gas supply pipeline of the gas storage tank and a powder supply pipeline of the powder tank;
The bottom blowing element is positioned at the bottom of the molten iron runner, is connected with the gas-powder mixing fluidization chamber through a blowing pipeline, and blows the gas powder mixed fluidization in the gas-powder mixing fluidization chamber into the molten iron runner through the bottom blowing element.
Further, the bottom blowing element comprises a first bottom blowing element and a second bottom blowing element: the first bottom blowing element is connected with a desulfurization gas-powder mixing fluidization chamber, and the desulfurization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an inert gas storage tank through an ejector and is connected with a powder supply pipeline of a desulfurization powder tank; the second bottom blowing element is connected with a desilication and dephosphorization gas-powder mixing fluidization chamber, and the desilication and dephosphorization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an oxygen gas storage tank through an ejector and is connected with a powder supply pipeline of a desilication and dephosphorization powder tank;
The molten iron runner comprises a first molten iron runner and a second molten iron runner, the first molten iron runner comprises a turbulence zone and a slag-iron separation zone, and the second molten iron runner is positioned behind the skimmer;
the first bottom blowing element is arranged at the bottom of the turbulent flow area, and the second bottom blowing element is arranged at the bottom of the second molten iron runner.
Further, two powder tanks are used for storing desulfurization powder and desilication dephosphorization powder respectively; when the powder tanks are two: the two gas tanks comprise an inert gas tank for desulfurizing powder carrier gas and an oxygen gas tank for desilicating dephosphorizing powder carrier gas; the two gas-powder mixing fluidization chambers and the two ejectors are respectively arranged, the number of the first bottom blowing elements is one, and the number of the second bottom blowing elements is one.
Or three powder tanks are respectively used for storing desulfurization powder, desilication powder and dephosphorization powder; when the powder tank is three, the gas storage tanks are three, and each gas storage tank comprises an inert gas storage tank for desulfurizing powder carrier gas, an oxygen gas storage tank for desilicating powder carrier gas and an oxygen gas storage tank for dephosphorizing powder carrier gas, the number of the gas-powder mixing fluidization chamber and the number of the ejectors are correspondingly three, the number of the first bottom blowing elements is one, and the number of the second bottom blowing elements is two.
Further, a fluidization pipeline is arranged at the lower part of the powder tank, and inert gas is blown into the powder tank through the fluidization pipeline.
Further, the gas-powder mixing fluidization chamber comprises a mixing chamber and stirring paddles, wherein the stirring paddles are used for uniformly stirring powder in the mixing chamber and distributing the powder in carrier gas; the outlet diameter of the air inlet pipe of the ejector is smaller than the inlet diameter.
Further, the bottom blowing element is an air brick made of refractory materials; the bottom blowing element is a single pore channel or a multi-pore channel; the diameter of the single hole is 6-15 mm; the diameter of the porous is 0.5-8 mm, and the number of the porous is 2-200.
Further, when the bottom blowing element is a multi-channel, a gas-powder buffer chamber is arranged below the bottom blowing element, and the gas-powder buffer chamber is connected with the gas-powder mixing fluidization chamber through a blowing pipeline.
In a second aspect of the invention, a method for desulfurizing, desilicating and dephosphorizing molten iron runner bottom powder injection is provided, wherein in the process of tapping a blast furnace, desulfurization gas powder is injected into molten iron flow through a first bottom blowing element arranged at the bottom of a first molten iron runner turbulence zone, so as to complete molten iron pretreatment desulfurization; and (3) spraying mixed gas powder of desilication and dephosphorization or spraying desilication gas powder and dephosphorization gas powder respectively into the molten iron subjected to desulfurization and skimming treatment through a second bottom blowing element arranged at the bottom of the second molten iron channel, so as to finish desilication and dephosphorization of the molten iron.
Further, the carrier gas of the desulfurizing gas powder is inert gas, and the carrier gas of the desilicating gas powder and the dephosphorizing gas powder is oxygen.
Further, the particle sizes of the desulfurization powder, the desilication powder and the dephosphorization powder are all smaller than 100 meshes; the pressure of the gas sprayed is 0.4-2 MPa, the flow rate of the gas is 200-2000 NL/min, the quantity of the powder sprayed is 60-600 kg/min, and the gas-powder volume ratio of the carrier gas and the powder in the gas-powder mixing fluidization chamber is greater than 10:1.
Compared with the prior art, the invention at least comprises the following beneficial effects:
according to the device for desulfurizing, desilicating and dephosphorizing by spraying powder at the bottom of the molten iron channel, disclosed by the invention, in the process of tapping of a blast furnace, desulfurizing, desilicating and dephosphorizing gas powder is sprayed into molten iron through the bottom blowing element arranged at the bottom of the molten iron channel, so that desulfurizing, desilicating and dephosphorizing treatment at the bottom of the molten iron channel are performed, and the advantages of no additional occupied treatment time, smaller molten iron temperature drop and convenience in slag-iron separation in the traditional molten iron channel molten iron pretreatment are maintained; meanwhile, the carrier gas plays a role in stirring molten iron, so that reactants and molten iron are fully mixed, the reaction efficiency of the molten iron is improved, the yield of the reactants is improved, and the pretreatment desulfurization, desilication and dephosphorization costs are reduced; and the method of injection metallurgy is adopted, so that the treatment capacity is increased, and the removal efficiency is high and stable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
Fig. 1 is a schematic diagram of the overall composition of a device for powder injection desulfurization, desilication and dephosphorization at the bottom of a molten iron trench according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of the position of a bottom blowing element of a device for desulfurizing, desilicating and dephosphorizing molten iron trench bottom powder injection according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of an ejector and a gas-powder mixing fluidization chamber of a device for desulfurizing, desilicating and dephosphorizing molten iron trench bottom powder injection provided by an embodiment of the invention.
Fig. 4 is a top view of a porous bottom blowing element of a device for desulfurizing, desilicating and dephosphorizing molten iron trench bottom powder injection according to an embodiment of the present invention.
Fig. 5 is a cross-sectional view of a porous bottom blowing element of a device for desulfurizing, desilicating and dephosphorizing molten iron runner bottom powder injection according to an embodiment of the present invention.
Fig. 6 is a top view of a single hole bottom blowing element of a device for desulfurizing, desilicating and dephosphorizing molten iron trench bottom powder injection according to an embodiment of the present invention.
Fig. 7 is a cross-sectional view of a single hole bottom blowing element of a device for desulfurizing, desilicating and dephosphorizing molten iron trench bottom powder injection according to an embodiment of the present invention.
Wherein, the correspondence between the reference numerals and the component names is:
1. A gas storage tank; 101. a pressure gauge; 102. a gas storage tank valve; 103. an air supply line; 2. a powder tank; 201. a fluidization line; 202. a powder tank valve; 203. a powder supply pipeline; 3. a gas-powder mixing fluidization chamber; 301. a mixing chamber; 302. stirring paddles; 4. an ejector; 5. a bottom blowing element; 501. a first bottom blowing element; 502. a second bottom blowing element; 503. a duct; 6. molten iron runner; 601. a first molten iron runner; 6011. a turbulent flow zone; 6012. a slag-iron separation zone; 602. a second molten iron runner; 7. tapping channel; 8. molten iron; 9. slag; 10. slag runner; 11. skimming tool; 12. a blowing pipeline; 13. and a gas-powder buffer chamber.
Detailed Description
In order to better understand the above technical solutions, the following detailed description of the technical solutions of the embodiments of the present application is made by using the accompanying drawings and the specific embodiments, and it should be understood that the specific features of the embodiments of the present application are detailed descriptions of the technical solutions of the embodiments of the present application, and not limit the technical solutions of the present application, and the technical features of the embodiments of the present application may be combined with each other without conflict.
Referring to fig. 1 to 7, in a first aspect of the embodiment of the present invention, there is provided a device for desulfurizing, desilicating and dephosphorizing molten iron runner bottom powder injection, comprising:
A gas tank 1 for storing a carrier gas;
A powder tank 2 for storing desulfurization, desilication and dephosphorization powder;
the gas-powder mixing fluidization chamber 3 is used for mixing and fluidizing carrier gas and desulfurization, desilication and dephosphorization powder; the gas-powder mixing fluidization chamber 3 is respectively connected with a gas supply pipeline of the gas storage tank 1 and a powder supply pipeline of the powder tank 2;
the bottom blowing element 5 is positioned at the bottom of the molten iron runner 6, the bottom blowing element 5 is connected with the gas-powder mixing and fluidizing chamber 3 through a blowing pipeline, and the gas-powder mixed and fluidized in the gas-powder mixing and fluidizing chamber 3 is blown into the molten iron runner 6 through the bottom blowing element 5.
According to the device for desulfurizing, desilicating and dephosphorizing by spraying the powder at the bottom of the molten iron channel, in the process of tapping the blast furnace, the powder is sprayed into the molten iron channel in a bottom blowing mode to perform desulfurizing, desilicating and dephosphorizing treatment on the bottom of the molten iron channel, so that the advantages of no extra occupied treatment time, small temperature drop of molten iron and convenience in slag-iron separation in the traditional molten iron channel molten iron pretreatment are maintained; meanwhile, the carrier gas plays a role in stirring molten iron, so that reactants and molten iron are fully mixed, the reaction efficiency of the molten iron is improved, the yield of the reactants is improved, and the pretreatment desulfurization, desilication and dephosphorization costs are reduced; and the method of injection metallurgy is adopted, so that the treatment capacity is increased, and the removal efficiency is high and stable.
Specifically, in the process of tapping molten iron from a blast furnace, due to the bottom blowing mode, gas powder is directly blown into the deep part of molten iron, and under the combined action of stirring of carrier gas and impact of molten iron, powder and molten iron can be fully mixed, the specific surface area of the molten iron in contact with the powder is increased, the reaction dynamics condition is improved, the effective utilization efficiency of the powder is improved, and the deep desulfurization, desilication and dephosphorization are facilitated.
In some possible embodiments, the bottom blowing element 5 comprises a first bottom blowing element 501 and a second bottom blowing element 502: the first bottom blowing element 501 is connected with a desulfurization gas-powder mixing fluidization chamber, and the desulfurization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an inert gas storage tank through an ejector 4 and is connected with a powder supply pipeline of a desulfurization powder tank; the second bottom blowing element 502 is connected with a desilication and dephosphorization gas-powder mixing fluidization chamber, and the desilication and dephosphorization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an oxygen gas storage tank through an ejector 4 and is connected with a powder supply pipeline of a desilication and dephosphorization powder tank; the molten iron runner 6 comprises a first molten iron runner 601 and a second molten iron runner 602, the first molten iron runner 601 comprises a turbulence zone 6011 and a slag-iron separation zone 6012, and the second molten iron runner 602 is positioned behind the skimmer 11; the first bottom blowing element 501 is disposed at the bottom of the turbulent zone 6011 and the second bottom blowing element 502 is disposed at the bottom of the second molten iron runner 602.
In the technical scheme, because the desulfurization is performed in the position of the turbulent flow area 6011 of the first molten iron runner 601 in front of the furnace, namely the main molten iron runner, the temperature of the molten iron is high, the oxygen content is low, the thermodynamic conditions of the desulfurization reaction are met, the removal of harmful element sulfur is facilitated, the deep desulfurization of the molten iron can be performed, the quality of the subsequent molten steel is improved, meanwhile, the desulfurization product directly floats into a slag layer and is discharged into the slag runner 10 through the skimming device 11 for removal, and the possibility of molten iron resulfurization is reduced. And desilication and dephosphorization are carried out in the second molten iron channel 602 at the rear section, oxygen is used as carrier gas, the temperature of molten iron is reduced compared with that of desulfurization, and under the conditions of low temperature and high oxygen potential, silicon and phosphorus elements in the molten iron are more beneficial to removal, so that preparation is made for subsequent steelmaking treatment. In addition, the powder descends, and carrier gas accelerates through the ejector 4 to drive the powder to enter the gas-powder mixing fluidization chamber 3 together, so that the powder is prevented from being accumulated on a descending pipeline.
In some possible embodiments, the powder tanks 2 are two, respectively for storing the desulphurized powder and the desilicated dephosphorized powder; when the number of the powder tanks 2 is two: the two gas tanks 1 comprise an inert gas tank for desulfurizing powder carrier gas and an oxygen gas tank for desilicating dephosphorizing powder carrier gas; the number of the air-powder mixing fluidization chamber 3 and the number of the ejector 4 are two correspondingly, one first bottom blowing element and one second bottom blowing element.
Or, the number of the powder tanks 2 is three, and the three powder tanks are respectively used for storing desulfurization powder, desilication powder and dephosphorization powder; when the number of the powder tanks 2 is three, the number of the air tanks 1 is three, and the air tanks comprise an inert gas storage tank for desulfurizing powder carrier gas, an oxygen storage tank for desilicating powder carrier gas and an oxygen storage tank for dephosphorizing powder carrier gas, the number of the gas-powder mixing fluidization chamber 3 and the ejector 4 is correspondingly three, one first bottom blowing element is arranged, and the number of the second bottom blowing elements is two.
In this embodiment, the number of the air tanks 1, the air-powder mixing fluidization chamber 3 and the bottom blowing elements 5 (including the first bottom blowing element 501 and the second bottom blowing element 502) is matched with the number of the powder tanks 2. The gas storage tank 1 is provided with a pressure gauge 101, the gas outlet of the gas storage tank 1 is provided with a gas storage tank valve 102, and the pressure and flow of carrier gas are controlled through the gas storage tank valve 102; the discharge port of the powder tank 2 is provided with a powder tank valve 202, and the descending speed of the powder is controlled by the opening of the powder tank valve 202.
In some possible embodiments, a fluidization line 201 is provided at the lower part of the powder tank 2, and inert gas is blown into the powder tank 2 through the fluidization line 201.
In this technical scheme, fluidization pipeline 201 is equipped with to powder jar 2 lower part, and fluidization pipeline 201 can install in powder jar 2 lower part about 1/3 jar body height department, and through fluidization pipeline 201 to the powder jar 1 in-injection inert gas (optional argon gas), on the one hand makes the powder motion of piling up, strengthens its mobility, on the other hand inert gas gets into the powder jar and can increase the intra-tank atmospheric pressure, plays top pressurized effect in the powder descending process, guarantees smooth and straight going of powder descending.
In some possible embodiments, the gas-powder mixing fluidization chamber 3 includes a mixing chamber 301 and a stirring paddle 302, where the stirring paddle 302 is used to uniformly stir the powder in the mixing chamber 301 and distribute the powder in the carrier gas; the outlet diameter of the air inlet pipe of the ejector 4 is smaller than the inlet diameter.
In the technical scheme, the ejector 4 is of a contracted pipe structure, the inlet diameter of the outlet diameter of the air inlet pipe of the ejector 4 is smaller than that of the inlet of the air inlet pipe of the ejector, the inlet flow speed of the air-powder mixing fluidization chamber 3 can be increased to ensure that descending powder is not accumulated at the inlet of the air-powder mixing fluidization chamber 3 to cause blockage, the air-powder flow is stirred by the stirring paddle 302 to enable powder to be distributed more uniformly in carrier gas, the flow performance of the air-powder flow is improved, and the possibility that the powder blocks a pipeline is further reduced.
In some possible embodiments, the bottom blowing element 5 is an air brick made of refractory material; the bottom blowing element 5 is a single pore channel or a multi-pore channel; the diameter of the single hole is 6-15 mm; the diameter of the porous is 0.5-8 mm, and the number of the porous is 2-200.
In this technical scheme, as shown in fig. 4 to 7, the bottom blowing element 5 is made of refractory material, and may be in the shape of a cylinder, a truncated cone, a square, or the like; the bottom blowing element 5 is provided with at least one pore canal penetrating through the bottom blowing powder-spraying air brick, the diameter of a single pore canal is set to be 6-15 mm, the diameter of multiple pore canals is set to be 0.5-8 mm, and the number of the multiple pore canals is 2-200, so that carrier gas can carry powdery desulfurizing, desilicating and dephosphorizing agents to be sprayed into molten iron through penetrating holes of the bottom blowing powder-spraying air brick. However, since the single Kong Buyi is clogged, the leakage of molten iron is liable to occur under a large aperture, and therefore, a larger amount of air and powder than those of the porous air-permeable element are required for the mixing, and the powder is liable to be clogged under a large blowing amount of the porous air-permeable element, and the blowing can be carried out by mixing a small amount of air and powder.
In some possible embodiments, when the bottom blowing element 5 is multi-channel, a gas-powder buffer chamber 13 is disposed below the bottom blowing element 5, and the gas-powder buffer chamber 13 is connected with the gas-powder mixing fluidization chamber 3 through a blowing pipe 12.
In this technical solution, as shown in fig. 5, for the porous bottom blowing element, in order to avoid powder blocking the channels, a gas-powder buffer chamber 13 is provided, the gas-powder buffer chamber 13 providing a space for the powder to flow.
In a second aspect of the embodiment of the invention, a method for desulfurizing, desilicating and dephosphorizing molten iron runner bottom powder injection is provided, wherein in the process of tapping of a blast furnace, desulfurization gas powder is injected into molten iron flow through a first bottom blowing element arranged at the bottom of a first molten iron runner turbulence zone, so as to complete pretreatment desulfurization of molten iron; and (3) spraying mixed gas powder of desilication and dephosphorization or spraying desilication gas powder and dephosphorization gas powder respectively into the molten iron subjected to desulfurization and skimming treatment through a second bottom blowing element arranged at the bottom of the second molten iron channel, so as to finish desilication and dephosphorization of the molten iron. The carrier gas of the desulfurization gas powder is inert gas, and the carrier gas of the desilication gas powder and the dephosphorization gas powder is oxygen.
In the method for desulfurizing, desilicating and dephosphorizing by spraying powder at the bottom of a molten iron runner, inert gas (such as argon, nitrogen or argon-nitrogen mixed gas) is used as carrier gas of desulfurizing powder in the tapping process of a blast furnace, and a first bottom blowing element 501 arranged in a turbulent flow area 6011 of a first molten iron runner 601 (main runner) is used for blowing powdery desulfurizing agent into molten iron flow. The desulfurization powder enters a molten iron turbulence zone (the molten iron has high temperature and low oxygen content, and is favorable for the forward progress of desulfurization reaction) through the bottom blowing element, the specific surface area of the powder desulfurizing agent for reaction with the molten iron is increased, and the desulfurization reaction rate of the molten iron is improved; meanwhile, under the combined action of stirring of carrier gas on molten iron and impact of molten iron flow, the bubble crushing effect is good, more powder wrapped by the bubble enters the molten iron, so that the desulfurizing agent is fully mixed with the molten iron, the reaction efficiency of the desulfurizing agent and the molten iron is increased, the reaction rate of the desulfurizing agent is improved, the purpose of desulfurizing the molten iron pretreatment is better completed, a desulfurizing product goes up to enter slag, and enters a slag runner for removal through a skimming device, so that the possibility of molten iron sulfur reversion is reduced; the second bottom blowing element arranged at the rear of the slag skimmer 11, namely at the bottom of the second molten iron channel, blows mixed powder of desilication and dephosphorization into the desulfurized molten iron, or blows desilication and dephosphorization powder respectively (the desulfurized powder needs to be stored in a separate storage tank, namely a set of independent bottom powder blowing equipment is needed, the desilication powder and the dephosphorization powder can be stored in a mixed mode, and the set of bottom powder blowing equipment can be shared), the carrier gas at the moment is oxygen, the temperature of the molten iron at the moment is already reduced after desulfurization treatment, the desilication and the dephosphorization are exothermic reactions, the forward progress of the reactions is facilitated by high oxygen potential and low temperature, the bottom blown powder enters the molten iron under the drive of the oxygen, and silicon and phosphorus in the molten iron are removed, so that the subsequent smelting work is laid.
In some possible embodiments, the particle size of the desulfurization powder, the desilication powder, and the dephosphorization powder are all less than 100 mesh; the pressure of the gas sprayed is 0.4-2 MPa, the flow rate of the gas is 200-2000 NL/min, the quantity of the powder sprayed is 60-600 kg/min, and the gas-powder volume ratio of the carrier gas and the powder in the gas-powder mixing fluidization chamber is greater than 10:1.
In the technical scheme, the gas-powder ratio of carrier gas to descending powder in the gas-powder mixing fluidization chamber 3 is more than 10:1, so that the flow of particles in a pipeline is ensured to be dilute phase conveying, and the particles are prevented from being blocked in the pipeline. The particle size of the desulfurization powder, the desilication powder and the dephosphorization powder is required to be below 100 meshes, on one hand, the mobility of small-size particles is better, and on the other hand, the smaller the particle size is, the smaller the porosity is, and the fluidization pipeline 201 on the powder tank is more easy to fluidize. The pressure of the air blowing gas is 0.4-2 MPa, and the proper gas pressure can prevent blockage and ensure the service life of the pipeline; the flow rate of the gas is 200-2000 NL/min, the sprayed powder dosage is 60-600 kg/min, the gas flow rate and the sprayed powder dosage are in one-to-one correspondence to ensure sufficient gas-powder ratio, and meanwhile, the gas flow rate is not excessively high to prevent the molten iron from splashing.
TABLE 1 pretreatment data of molten iron in certain Steel works
Initial mass content% End point mass content% Powder unit consumption kg/t
S 0.034 0.007 8.65
Si 0.3 0.09 13
P 0.12 0.015 51
Table 1 shows the pretreatment data of molten iron in a certain steel plant, the desulfurization capacity is taken as an example, the sulfur content of pig iron in China changes in a wider range along with the raw material conditions of each plant and the steel smelting process, the sulfur content is about 0.03 percent in a certain steel plant as an example, the tapping temperature is generally 1500 ℃, the temperature drop from a skimming device to a tapping spout of the common molten iron pretreatment process molten iron is 5-17 ℃, the maximum temperature drop when the molten iron flows into a molten iron tank is 37-79 ℃, the average temperature drop is 60 ℃, the slag skimming temperature drop is 12 ℃ on average, the average temperature drop in the transportation process is 23 ℃ per hour, and the temperature drop from the prior process molten iron to a desulfurization station is approximately 100 ℃. The sulfur removal needs to meet the conditions of high temperature, high alkalinity, large slag quantity and low oxygen potential of 3 high and low, the removal rate of the temperature to molten iron is particularly remarkable, the bottom powder spraying desulfurization is carried out at the front end of the tapping channel, and the desulfurization temperature is 1500 ℃ higher than the prior art temperature by 100 ℃. Meanwhile, the oxygen content of molten iron discharged from the blast furnace is extremely low, which is beneficial to the removal of elemental sulfur. According to the application, the desulfurizing agent is sprayed into molten iron in a high-temperature state in a bottom powder spraying mode, and under the combined action of the impact of molten iron flow and air bubble stirring in a turbulence area, the powder is fully mixed with the molten iron, so that the dynamic condition of the reaction is greatly improved, the reaction speed of desulfurization is accelerated, the time cost is reduced, the desulfurizing capability is enhanced, the sulfur content can be stably controlled to be 0.005%, the utilization rate of the desulfurizing agent is improved, and even the extremely low sulfur treatment is carried out to be 0.002%; on the other hand, the utilization rate of the desulfurizing agent is improved, and the unit consumption can be reduced by 40 to 60 percent.
The silicon and phosphorus removal is carried out in an oxidizing atmosphere, in the prior art, oxygen is mostly blown into a reactor through an oxygen gun, desilication and dephosphorization agents are added through a throwing or spraying mode, and the spraying is mostly top spraying and side spraying. According to the application, oxygen is used as carrier gas for transporting powder, and the reactive powder is sprayed into molten iron in a bottom powder spraying mode, so that on one hand, the oxygen and the powder directly enter the molten iron, the oxygen content in the molten iron is improved, and an oxidizing atmosphere is provided for desilication and dephosphorization reactions; on the other hand, the powder and the oxygen are fully mixed with the molten iron, so that the dynamic conditions of the reaction are improved, the reaction speed and the utilization rate of the powder are further improved, and the unit consumption and the time cost of the powder are reduced. In addition, as the arrangement position is the rear end of the molten iron runner slag skimmer, the desulfurization product at the moment is removed in slag, so that the possibility of sulfur recovery is reduced, and the temperature of molten iron is reduced through bottom powder injection desulfurization reaction and slag skimming. Desilication and dephosphorization are exothermic reactions, and proper low temperatures can further increase the rate of reaction.
In summary, the invention also has the following technical effects:
(1) The desulfurization, desilication and dephosphorization are directly carried out in the process of tapping the blast furnace, extra treatment time is not occupied, exothermic reaction is carried out in the process of desilication and dephosphorization, the temperature drop of the molten iron is small, and the subsequent temperature rising cost is saved.
(2) The desulfurization, desilication and dephosphorization are carried out in the molten iron runner, and the slag-iron separation is more convenient.
(3) The process does not change the original production pattern, only needs to add the bottom blowing powder-spraying air brick communicated with the gas-powder mixing and fluidizing device at the bottom of the molten iron channel, and has simple operation, small investment and small occupied area.
(4) Greatly improves the utilization rate of powder, saves desulfurizing, desilicating and dephosphorizing agents, is beneficial to deep desulfurization, silicon and phosphorus, and is easier to meet the requirements of pre-desulfurization, desilication and dephosphorization of molten iron.
(5) The device has strong operability and can be adjusted at any time according to the field conditions.
Example 1
As shown in fig. 1 to 3, the device for desulfurizing, desilicating and dephosphorizing the bottom powder of the molten iron trench comprises a gas storage tank 1, a powder tank 2, a gas-powder mixing fluidization chamber 3 and a bottom blowing element 5, wherein the bottom blowing element 5 is positioned at the bottom of a molten iron trench 6, the bottom blowing element 5 is connected with the gas-powder mixing fluidization chamber 3 through a blowing pipeline 12, and the gas-powder mixed fluidization chamber 3 is mixed and fluidized with the gas-powder through the bottom blowing element 5 to be blown into the molten iron trench 6.
In embodiment 1, two gas tanks 1 are provided, including a gas tank for storing inert gas (for desulfurization) and oxygen (for desilication and dephosphorization), two powder tanks 2 are provided, including a desulfurizing powder tank and a desilication dephosphorizing powder tank, two corresponding gas-powder mixing fluidization chambers 3 are provided, and two bottom blowing elements 5 are provided, wherein a first bottom blowing element 501 is provided at the bottom of the turbulent zone 6011, and a second bottom blowing element 502 is provided at the bottom of the second molten iron channel 602. The first bottom blowing element 501 is used for blowing desulfurization gas powder, and the second bottom blowing element 502 is used for blowing desilication dephosphorization gas powder.
The desulfurizing agent in the desulfurizing powder tank is mixed powder of CaO and CaF, the desilicating agent and dephosphorizing agent in the desulfurizing powder tank are mixture of oxidant (iron scale), slag forming agent (CaO) and fluxing agent (Na 2CO3), and the granularity of the powder is required to be 80-100 meshes. The specific surface area of the desulfurizing, desilicating and dephosphorizing agent entering into the molten iron is large enough to make the desulfurizing, desilicating and dephosphorizing agent react fully, so that the effective utilization coefficient of the desulfurizing, desilicating and dephosphorizing agent is ensured. The air storage tank 1 and the powder tank 2 are respectively connected with the gas-powder mixing fluidization chamber 3 through communication pipelines. The flow rate of the gas is controlled to be 200-2000 NL/min, the flow rate of powder in unit time can be measured through a weighing sensor of the powder tank, the amount of sprayed powder is 60-600 kg, the gas-powder ratio of the gas-powder mixing fluidization chamber 3 is required to be more than 10, and under the condition, the carrier gas can carry the powder agent to be a dilute phase and is conveyed through a communicated jetting pipeline 12 to a bottom blowing element 5 (air brick), so that the blocking phenomenon is not easy to occur.
The method for pretreating molten iron by using the powder injection desulfurization, desilication and dephosphorization device at the bottom of the molten iron channel in the embodiment 1 comprises the following specific steps:
step one: the assembly work of the device is carried out according to the device diagram shown in fig. 1, the parts are connected by the communicating pipe, all valves are in the closed state at this time, and the air tightness of the device and the smoothness of the pipe are monitored.
Step two: the gas in the gas storage tank is ensured to be sufficient, and the flow rate of the gas can reach 200-2000 NL/min when the valve is opened due to sufficient pressure. The powder is accurately weighed by a weighing sensor so as to ensure that the ratio of the falling quantity of the powder in unit time to the carrier gas after the valve is opened is more than 10. The air brick is fixed at the bottom of the molten iron runner, and whether the small hole is unobstructed or not is checked.
Step three: when the blast furnace is tapping, firstly, the valve of the air storage tank is opened, and the gas is kept to reach the bottom blowing element, so that the risks of keeping the pipeline smooth and preventing the molten iron from leaking along the bottom blowing element are reached, then, the valve of the powder tank is opened from small to large, the carrier gas and the powder meet in the gas-powder mixing fluidization device through the communication pipeline and are fully mixed, and then, the carrier gas and the powder are transported to the bottom of the molten iron channel through the pipeline and are sprayed into the molten iron through the air brick. The desulfurizing, desilicating and dephosphorizing agent enters into the deep part of the molten iron and is fully mixed with the molten iron, and fully reacts to achieve the effects of desulfurizing, desilicating and dephosphorizing the molten iron pretreatment.
Example 2
The apparatus shown in fig. 1 is used for carrying out the pre-desulfurization, desilication and dephosphorization treatments of the molten iron. Wherein, the desulfurizing agent is CaF powder, the desilication and dephosphorization agent is sinter powder, and the granularity of the powder is required to be 80-100 meshes. When the blast furnace is tapped, caF powder flows down through a powder tank valve 202 after being fluidized by a fluidization pipeline 201, is uniformly mixed with inert gas carrier gas by a gas-powder mixing fluidization chamber 3, is transported by a blowing pipeline 12, is sprayed into a turbulent flow area 6011 of a molten iron runner by a first bottom blowing element 501, and is broken by impact under the action of molten iron flow, a large amount of powder carried by gas is released into molten iron, and is rapidly reacted with sulfur element in the molten iron to be removed together with the powder entering the molten iron through penetrating bubbles, so that CaS floating is captured by slag, and is discharged into a slag runner 10 along with slag 9 by a slag skimmer 11 to be removed. And then, spraying sinter powder into the desulfurized molten iron through a second bottom blowing element 502, wherein carrier gas is oxygen, and a high-oxygen-potential reaction atmosphere is provided, so that the sinter powder fully reacts with free silicon and phosphorus in the molten iron to play a role in desilication and dephosphorization.
In the present invention, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more, unless expressly defined otherwise. The terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; "coupled" may be directly coupled or indirectly coupled through intermediaries. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or units referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present invention.
In the description of the present specification, the terms "one embodiment," "some embodiments," "particular embodiments," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The device for desulfurizing, desilicating and dephosphorizing the bottom powder injection of the molten iron trench is characterized by comprising:
a gas storage tank (1) for storing a carrier gas;
The powder tank (2) is used for storing desulfurization, desilication and dephosphorization powder;
the gas-powder mixing fluidization chamber (3) is used for mixing and fluidizing carrier gas and desulfurization, desilication and dephosphorization powder; the gas-powder mixing fluidization chamber (3) is respectively connected with a gas supply pipeline of the gas storage tank (1) and a powder supply pipeline of the powder tank (2);
The bottom blowing element (5), bottom blowing element (5) are located iron runner (6) bottom, bottom blowing element (5) through the jetting pipeline with gas-powder mixing fluidization room (3) are connected, through bottom blowing element (5) will gas-powder mixing fluidization room (3) mix the gas-powder jetting of fluidization get into in iron runner (6).
2. The device for desulphurizing, desilicating and dephosphorizing the bottom-blown ladle according to claim 1, characterized in that said bottom-blowing element (5) comprises a first bottom-blowing element (501) and a second bottom-blowing element (502): the first bottom blowing element (501) is connected with a desulfurization gas-powder mixing fluidization chamber, and the desulfurization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an inert gas storage tank through an ejector (4) and is connected with a powder supply pipeline of a desulfurization powder tank; the second bottom blowing element (502) is connected with a desilication and dephosphorization gas-powder mixing fluidization chamber, and the desilication and dephosphorization gas-powder mixing fluidization chamber is connected with a gas supply pipeline of an oxygen gas storage tank through an ejector (4) and is connected with a powder supply pipeline of a desilication and dephosphorization powder tank;
The molten iron runner (6) comprises a first molten iron runner (601) and a second molten iron runner (602), the first molten iron runner (601) comprises a turbulence zone (6011) and a slag-iron separation zone (6012), and the second molten iron runner (602) is positioned behind the skimmer (11);
the first bottom blowing element (501) is arranged at the bottom of the turbulence zone (6011), and the second bottom blowing element (502) is arranged at the bottom of the second molten iron runner (602).
3. The device for desulfurizing, desilicating and dephosphorizing by ladle bottom powder injection according to claim 2, characterized in that the number of the powder tanks (2) is two, and the two are respectively used for storing desulfurizing powder and desilicating and dephosphorizing powder; when the number of the powder tanks (2) is two: the two gas tanks (1) comprise an inert gas tank for desulfurizing powder carrier gas and an oxygen gas tank for desilicating dephosphorizing powder carrier gas; the two gas-powder mixing fluidization chambers (3) and the two ejectors (4) are respectively arranged, the number of the first bottom blowing elements is one, and the number of the second bottom blowing elements is one;
Or the powder tanks (2) are used for storing desulfurization powder, desilication powder and dephosphorization powder respectively; when the powder tank (2) is three, the gas storage tanks (1) are three, and each gas storage tank comprises an inert gas storage tank for desulfurizing powder carrier gas, an oxygen gas storage tank for desilicating powder carrier gas and an oxygen gas storage tank for dephosphorizing powder carrier gas, the number of the gas-powder mixing fluidization chamber (3) and the number of the ejector (4) are correspondingly three, the number of the first bottom blowing elements is one, and the number of the second bottom blowing elements is two.
4. The device for desulfurizing, desilicating and dephosphorizing by ladle bottom powder injection according to claim 1, characterized in that the lower part of the powder tank (2) is provided with a fluidization pipeline (201), and inert gas is injected into the powder tank (2) through the fluidization pipeline (201).
5. The device for desulfurizing, desilicating and dephosphorizing the molten iron trench bottom powder injection according to claim 2, characterized in that the gas-powder mixing fluidization chamber (3) comprises a mixing chamber (301) and stirring paddles (302), wherein the stirring paddles (302) are used for uniformly stirring powder in the mixing chamber (301) and distributing the powder in a carrier gas; the outlet diameter of the air inlet pipe of the ejector (4) is smaller than the inlet diameter.
6. The device for desulfurizing, desilicating and dephosphorizing the bottom of the molten iron runner according to claim 1, characterized in that the bottom blowing element (5) is an air brick made of refractory material; the bottom blowing element (5) is a single pore canal or a multi-pore canal; the diameter of the single hole is 6-15 mm; the diameter of the porous is 0.5-8 mm, and the number of the porous is 2-200.
7. The device for desulfurizing, desilicating and dephosphorizing the molten iron trench bottom powder injection according to claim 6, wherein when the bottom blowing element (5) is a multi-channel, a gas powder buffer chamber (13) is arranged below the bottom blowing element (5), and the gas powder buffer chamber (13) is connected with the gas powder mixing fluidization chamber (3) through a blowing pipeline (12).
8. The method for desulfurizing, desilicating and dephosphorizing by using the device for desulfurizing, desilicating and dephosphorizing by using the powder injection at the bottom of the molten iron runner according to any one of claims 1 to 7, which is characterized in that in the tapping process of a blast furnace, desulfurizing gas powder is injected into molten iron flow through a first bottom blowing element arranged at the bottom of a turbulent flow zone of a first molten iron runner to complete pretreatment desulfurization of the molten iron; and (3) spraying mixed gas powder of desilication and dephosphorization or spraying desilication gas powder and dephosphorization gas powder respectively into the molten iron subjected to desulfurization and skimming treatment through a second bottom blowing element arranged at the bottom of the second molten iron channel, so as to finish desilication and dephosphorization of the molten iron.
9. The method for desulfurizing, desilicating and dephosphorizing by bottom-runner powder injection according to claim 8, wherein the carrier gas of the desulfurizing gas powder is inert gas, and the carrier gases of the desilicating gas powder and the dephosphorizing gas powder are oxygen.
10. The method for desulfurizing, desilicating and dephosphorizing by ladle bottom powder injection according to claim 9, wherein the particle size of the desulfurizing powder, the desilicating powder and the dephosphorizing powder is less than 100 meshes; the pressure of the gas sprayed is 0.4-2 MPa, the flow rate of the gas is 200-2000 NL/min, the quantity of the powder sprayed is 60-600 kg/min, and the gas-powder volume ratio of the carrier gas and the powder in the gas-powder mixing fluidization chamber is greater than 10:1.
CN202410115932.4A 2024-01-26 2024-01-26 Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch Pending CN118147385A (en)

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CN202410115932.4A CN118147385A (en) 2024-01-26 2024-01-26 Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch

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CN202410115932.4A CN118147385A (en) 2024-01-26 2024-01-26 Device and method for desulfurizing, desilicating and dephosphorizing through powder spraying at bottom of molten iron ditch

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