KR20190027606A - Flux and method for refining molten steel using the same - Google Patents

Abstract

The present invention relates to a flux and a molten steel refining method using the same comprising: a process of blowing oxygen to molten steel in an electric furnace to refine the molten steel; a process of discharging slag in the electric furnace through a port disposed outside the electric furnace after completing refining of the molten steel; and a process of inserting a stabilizer into the port. The stabilizer insertion process comprises a process of mixing a flux and solvent to prepare a stabilizer having the flux dissolved therein, and a process of spraying the stabilizer toward the slag. Accordingly, according to one embodiment of the present invention, it is prevented that the flux is broken or dust caused by breakage of the flux is generated when a conventional briquet-shaped flux is inserted through a hopper, thereby providing a higher slag stabilization effect due to the flux than a conventional method. Accordingly, sloping is able to be effectively suppressed or prevented when the slag is discharged through the port.

Description

TECHNICAL FIELD [0001] The present invention relates to a flux and a refining method using the same,

More particularly, the present invention relates to a flux capable of effectively suppressing slagging of slag, and a method for scouring a molten iron using the flux.

Chartered iron from the blast furnace is generally charged with talline and desulfurization in the pre-refining process and then with scrap iron in the converter. In order to remove C, Si, P, and Mn from the converter, oxygen is blown into the furnace using a lance, and calcium oxide (CaO) is added to the furnace for slagification.

When oxygen is blown into the furnace, silicon (Si) and phosphorus (P), which have relatively high oxygen affinity in the charcoal, first react with oxygen. At this time, silicon (Si) reacts with oxygen to produce SiO ₂ , and phosphorus (P) produces P ₂ O ₅ . The resulting SiO ₂ and P ₂ O ₅ are transferred to the slag in the molten bath surface and absorbed. Here, SiO _2, and is reacted with calcium oxide (CaO) charged into the initial blow, and thus the higher the viscosity of the slag.

When the primary winding is completed, the converter is tilted, the slag is discharged to the port (primary discharge), and the demolition and tallining of the charcoal are ended accordingly.

On the other hand, during the refinement of the converter, FeO, which is a main component of the slag, reacts with carbon in the molten steel, thereby generating a small amount of CO gas, that is, CO bubbles. The height of the slag in the converter is influenced by the rate of formation and disappearance rate of the CO bubbles. When the slag viscosity is high, the volume of the slag increases and the slag flows out of the converter. .

However, since the viscosity of the slag is high at the beginning of the blowing process, a large amount of CO bubbles can not pass through the slag layer, thereby increasing the volume or volume of the slag, thereby rapidly increasing the slag foaming phenomenon. When such a slag forming phenomenon occurs abruptly, slag overflowing out of the slag port occurs at the time of slag disposal.

Therefore, in order to prevent occurrence of sloping in the port, flux is injected into the slag in the port when discharging the slag to the port.

Conventionally, a flux generally used is a mixture of waste pulp and a carbonaceous material, and this flux is made into a briquetting shape, and is introduced into the slag through a hopper. In the case of such flux injection, there is a problem that the slag takes a long time to settle. In addition, as the flux is introduced through the hopper, the briquettes are broken and dust is generated as they fall, resulting in a problem of a slopping suppression effect, that is, a sedimentation efficiency.

Korean Patent No. KR1206952B1

The present invention provides a flux capable of soaking the slag and a method for scouring a molten iron using the same.

The present invention provides a flux capable of suppressing or preventing slag overflow of slag from a port at the time of slag disposal, and a method for scouring a charcoal using the same.

The present invention includes a sodium carbonate (Na ₂ CO ₃ ) and a sodium sulfate (Na ₂ SO ₄ ) as a flux to soot the slag generated in the steelmaking process.

In addition to the above sodium carbonate (Na ₂ CO ₃ ) and sodium sulfate (Na ₂ SO ₄ ), sodium chloride (NaCl) is further included.

It is preferable that the content of the sodium carbonate (Na ₂ CO ₃ ) is equal to the content of the sodium sulfate (Na ₂ SO ₄ ) or the content of the sodium sulfate (Na ₂ SO ₄ ) is larger than the content of the sodium carbonate (Na ₂ CO ₃ ) .

It is preferable that the content of the sodium carbonate (Na ₂ CO ₃ ) and the sodium sulfate (Na ₂ SO ₄ ) is larger than the content of the sodium chloride (NaCl).

The sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl) are obtained from the desulfurizing dust generated during the desulfurization of the exhaust gas generated during the production of the sintered ores.

The sedative according to the present invention comprises a solvent in which the flux and the flux are dissolved, and is in a solution or slurry state.

The solvent includes water.

A method for refining a charcoal according to the present invention includes the steps of refining the charcoal by blowing oxygen into a converter enclosure; Disposing the slag in the converter into a port disposed outside the converter after completion of the scouring; And injecting a sedative into the slag in the port, wherein the step of injecting the sedative comprises the steps of mixing a flux and a solvent to prepare a sediment in which the flux is dissolved; And spraying the sedative toward the slag.

In mixing the flux and the solvent, the sedative is mixed so as to be in a solution or slurry state.

In mixing the flux with the solvent, it is preferable to mix the flux: solvent in a ratio of 10: 1 to 2: 1.

The solvent includes water.

The flux includes sodium carbonate (Na ₂ CO ₃ ) and sodium sulfate (Na ₂ SO ₄ ).

The flux further comprises sodium chloride (NaCl).

The sodium carbonate, sodium sulfate and sodium chloride are obtained from the desulfurization dust generated during the desulfurization of the exhaust gas generated during the production of the sinter.

In injecting the sedative into the slag, nitrogen is injected together and injected.

According to the embodiment of the present invention, since the flux is broken or dust is not generated as in the conventional case when the flux in the form of briquettes is introduced through the hopper, the effect of soaking the slag due to the flux is higher than in the prior art. Thus, slagging can be more effectively suppressed or prevented when the slag is discharged to the port.

According to the embodiment of the present invention, since the flux is not broken or the dust due to the flux is not generated, the slag solving effect due to the flux is improved. Thus, slagging can be more effectively suppressed or prevented when the slag is discharged to the port.

1 is a block diagram showing a configuration of a flux according to a first embodiment of the present invention;
2 is a block diagram showing the configuration of a flux according to a second embodiment of the present invention
3 is a flowchart showing a method of producing a sedative and a method of injecting flux according to embodiments of the present invention
FIG. 4 is a graph showing an X-Ray Flourescence Spectrometry (XRF) graph showing the components of the desulfurizing dust

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. It is provided to inform. Wherein like reference numerals refer to like elements throughout.

The present invention relates to a flux capable of effectively suppressing the formation of slag and a method for scouring a charcoal using the same. More particularly, the present invention relates to a flux capable of suppressing or preventing slag overflowing, and a method for charging the flux. The flux according to the embodiment may be a flux injected into the slag in the port when discharging the slag in the converter to the port.

Hereinafter, a flux according to an embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

FIG. 1 is a block diagram showing the construction of a flux according to a first embodiment of the present invention. FIG. 2 is a block diagram showing the construction of a flux according to a second embodiment of the present invention. 3 is a flowchart showing a method of producing a sedative and a method of injecting flux according to embodiments of the present invention. 4 is an X-Ray Flourescence Spectrometry (XRF) graph showing the composition of the desulfurizing dust.

The flux according to the first embodiment of the present invention includes first and second raw materials including sodium. The flux, that is, the sodium component contained in each of the first and second raw materials, acts to suppress slag forming or slopping by lowering the melting point and viscosity of the slag when it is put into the slag.

The flux according to the first embodiment includes the first and second raw materials as described above wherein the first raw material is sodium carbonate (Na ₂ CO ₃ ), the second raw material is sodium sulfate (Na ₂ SO ₄ ), the sodium carbonate (Na ₂ CO ₃ ) and the sodium sulfate (Na ₂ SO ₄ ) are equal to each other or the sodium sulfate (Na ₂ SO ₄ ) is more than the sodium carbonate (Na ₂ CO ₃ ) content.

More specifically, the first raw material, that is, sodium carbonate (Na ₂ CO ₃ ) is contained in an amount of 10 wt% or more and 50 wt% or less, sodium sulfate (Na ₂ SO ₄ ) is 50 wt% or more, 90 wt% Or less.

The flux according to the first embodiment includes the first raw material of sodium carbonate (Na ₂ CO ₃ ) and the second raw material of sodium sulfate (Na ₂ SO ₄ ) as described above. However, the present invention is not limited thereto, and the flux may further include sodium chloride (NaCl) as a third raw material as in the second embodiment shown in FIG. That is, the other flux in the second embodiment includes sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl), and sodium carbonate (Na ₂ CO ₃ ) and sodium sulfate (Na ₂ SO ₄ ) (Na ₂ CO ₃ ) is not less than 10% by weight, not more than 45% by weight, sodium sulfate (Na ₂ SO ₄ ) is not less than 50% by weight, By weight or more, 90% by weight or less, and 1% by weight or more and 10% by weight or less of sodium chloride (NaCl).

Sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl) are used as the fluxes according to the second embodiment, that is, the first to third raw materials are byproducts generated during desulfurization of the exhaust gas generated during the sintering process Can be obtained. In other words, the flux recycles by-products generated during the desulfurization of the exhaust gas generated during the sintering process, as a raw material for the flux.

Hereinafter, the process of desulfurizing the sintered ores and the by-products will be briefly described.

When the blend material is charged into the bogie, the bogie proceeds in the sintering progressing direction and the sintering proceeds. At this time, suction force is generated in the wind box on the lower side of the truck, and the gas generated in the sintering process in the truck is transferred to the outside through the wind box and the duct connected to the wind box.

On the other hand, since the exhaust gas discharged from the vehicle contains SOx (sulfur oxide) such as SO ₂ and SO _{3 which} are harmful to the environment, the exhaust gas can not be directly discharged to the outside. Therefore, a desulfurizing agent capable of collecting S (sulfur) in the duct or separating S (sulfur) from the exhaust gas is introduced, and generally, the desulfurizing agent includes sodium hydrogencarbonate (NaHCO3).

Then, when desulfurization is carried out by reaction between the desulfurizing agent and the exhaust gas containing the sodium bicarbonate (NaHCO3), the desulfurization by-product is typically sodium carbonate (Na ₂ CO ₃₎ and sodium sulfate (Na ₂ SO _4), and contains a sodium chloride ( NaCl) (see Fig. 4). More particularly, the desulfurizing dust 100 wt%, 10 wt% or more and 50% by weight sodium carbonate (Na ₂ CO ₃₎ and of 50% by weight or more, or containing sodium sulfate of at most 90 wt% (Na ₂ SO _4), (Na ₂ CO ₃ ), 50% by weight or more, 90% by weight or less of sodium sulfate (Na ₂ SO ₄ ), 1 or more and 10 or less by weight based on 100% Or less by weight of sodium chloride (NaCl).

In the embodiment, the thus generated desulfurization dust is utilized as flux.

Conventionally, when desulfurizing dust is used as flux in the present invention, industrial by-products or wastes are recycled, thereby reducing the cost of preparing flux.

The flux according to the second embodiment is not limited to the recycling of the desulfurization dust but is separately prepared by preparing sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl) May be produced.

It is confirmed that the S (sulfur) concentration of the slag in the port due to the sodium sulfate in the flux is smaller than the amount of the slag in the port and increases by 0.1% at the maximum when the flux according to the first and second embodiments is used, It was judged that there was no environmental problem when recycling.

On the other hand, the conventional flux was manufactured into a briquetted state and introduced into the slag through the hopper. At this time, when the briquettes fall through the hopper, there is a problem that the effect of inhibiting slag foaming by flux is deteriorated as the dust is crushed and dust is generated.

Sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ), and sodium chloride (NaCl) contained in the flux according to the embodiment have a higher solubility in a solvent such as water than the conventional pulp pulp and carbon- .

Therefore, in the embodiments of the present invention, the flux is mixed with a solvent such as water and sprayed or sprinkled with slag as described above in order to solve the problem that the effect of the slag sediment is reduced by the generation of dust at the time of flux injection. In other words, the flux is not produced in the form of briquettes, but is prepared in the form of powder or powder, and mixed with a solvent so as not to generate dust, and is sprayed with slag. The reason why the flux can be dissolved in the solvent and injected into the slag is that the sodium carbonate, sodium sulfate and sodium chloride of the flux according to the embodiment have a high solubility in a solvent such as water, unlike the conventional flux.

Hereinafter, the mixture in which the flux and the solvent are mixed is referred to as a 'sedative'.

Hereinafter, with reference to FIG. 3, a method of applying a flux according to an embodiment of the present invention will be described. At this time, the flux according to the second embodiment will be described by way of example.

And, as a solvent which is mixed with the flux or in which the flux is dissolved, 'water' is explained as an example. Of course, the solvent is not limited to water, and various solvents capable of dissolving sodium carbonate, sodium sulfate and sodium chloride are applicable.

First, flux and water containing sodium-containing flux, namely, sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ), and sodium chloride (NaCl) are prepared (S 100, S 200).

Then, the flux and water are mixed (S300) to produce a sediment in the form of a solution or a slurry. When the flux and water are mixed, at least a portion of the flux is dissolved in water, and the components of each of the sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ), and sodium chloride (NaCl) have.

Further, depending on the mixing ratio of the flux and water, the sedative may be in a low-viscosity solution state or in a slurry state having a relatively high viscosity.

In the embodiment, in mixing the flux with water, the mixing ratio of flux to water is 1 (flux): 10 (water) to 2 (flux): 1 (water).

Then, the thus-prepared sedative is sprayed onto the surface of the slag by using a separate injection device such as a nozzle or an injector (S400). When the sedative is injected toward the slag surface using the injector, the sedative penetrates into the slag. The flux is injected into the slag in a state in which the flux is dissolved in water, so that no flux dust is generated as in the prior art, and the effect of soaking the slag by flux is improved as compared with the conventional art.

Then, when a sedative is added, sodium carbonate (Na ₂ CO ₃ ) in the flux reacts with water and is synthesized as sodium hydrogencarbonate (NaHCO ₃ ) as shown in the following reaction formula (1). And, sodium hydrogencarbonate (NaHCO3) generates gas while water evaporates at a temperature of about 150 캜. At a temperature of 900 占 폚 or higher, carbon dioxide (CO ₂ ) dissociates and generates gas.

Reaction formula)

Na ₂ CO ₃ + H ₂ O -> NaHCO ₃ + NaOH

2NaHCO ₃ -> Na ₂ CO ₃ + H ₂ O + CO ₂

Since the temperature of the slag discharged into the port is around 1400 ° C, when the sediment is injected into the slag, gas is generated from sodium hydrogencarbonate (NaHCO 3) according to the temperature of the slag. At this time, the generated gas forms a plurality of holes or channels in the slag, and bubbles, such as CO bubbles, are rapidly discharged through holes or channels. At this time, the flux of the sedative according to the embodiment is a low melting point material having a melting point of 650 ° C to 900 ° C. When the slag is charged into the slag, it has a low melting point at the interface and the discharge of bubbles is accelerated. With this bubble discharge, the volume or volume of the slag is inhibited from increasing, and thus the slag is soaked to prevent or prevent slag formation. That is, if the fine bubbles inside the slag are not released to the outside of the slag, the volume or volume of the slag is increased, and slag is caused to flow out over the slag. In the flux according to the embodiment, So that slag foaming can be suppressed or prevented.

In injecting the sedative using the injector, an inert gas such as nitrogen gas may be injected together with the injector. Herein, the inert gas injected together with the sedative agent may serve as a carrier gas to facilitate the injection of the sedative agent.

Further, in spraying the sedative using the injection device, it is preferable that the injection pressure is 4 bar or more. If the injection pressure is less than 4 bar, the sedative may be difficult to penetrate into the slag and the sedative effect may be lowered.

On the other hand, when the mixing ratio of flux: water is less than 1:10, slag soothing effect similar to the conventional flux and flux input method is exhibited. On the other hand, when the mixing ratio of flux and water exceeds 2: 1, there is a problem that the amount of water is insufficient and the jetting device, for example, the nozzle is clogged or an excessively large jetting pressure is required.

Hereinafter, a refining process using a flux and a flux injecting method according to an embodiment of the present invention will be described.

First, charcoal and scrap, which have been subjected to at least one pre-refining of desulfurization and talline, are charged into the converter.

Then, oxygen is blown into the converter using a lance (primary blowing), and calcium oxide (CaO) is added for slagification. When oxygen is blown into the furnace, silicon (Si) and phosphorus (P), which have relatively high oxygen affinity in the charcoal, first react with oxygen. At this time, silicon (Si) reacts with oxygen to produce SiO ₂ , and phosphorus (P) produces P ₂ O ₅ . The resulting SiO ₂ and P ₂ O ₅ are transferred to the slag in the molten bath surface and absorbed. Here, SiO _2, and is reacted with calcium oxide (CaO) charged into the initial blow, and thus the higher the viscosity of the slag.

When the primary winding is completed, the converter is tilted, and the slag is discharged to the port (primary discharge).

On the other hand, during the refinement of the converter, FeO, which is a main component of the slag, reacts with carbon in the molten steel, thereby generating a small amount of CO gas, that is, CO bubbles. However, in particular, since the viscosity of the slag is high at the beginning of the blowing operation, if a large amount of CO bubbles can not pass through the slag layer, the slag volume or volume increases and the slag foaming phenomenon increases sharply. When such a slag forming phenomenon occurs suddenly, slag overflowing out of the slag port occurs at the time of slag disposal

Therefore, when discharging the slag to the port, the flux is injected into the slag in the port so as to calm the slag, thereby suppressing the slag forming and preventing the slag. At this time, in the embodiment of the present invention, a flux containing sodium, that is, sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl) Here, the sodium component contained in the flux acts to lower the melting point and the viscosity of the slag when put into the slag, thereby suppressing the slag forming.

In addition, in the embodiment, the flux is mixed with the water to inject the flux, and the flux is injected by using a separate spraying jig, for example, a nozzle.

In mixing the flux and water, the mixture is mixed so that the mixing ratio of flux: water is 1 (flux): 10 (water) to 2 (flux): 1 (water). In this way, a sedative containing flux is a solution or slurry state, at least a portion of the flux is dissolved in water, sodium carbonate of the flux (Na ₂ CO _3), sodium sulfate (Na ₂ SO ₄₎ and sodium chloride (NaCl) is dissociated And may exist in an ionic state.

When the solution containing the flux or the sediment in the slurry state is prepared, it is supplied to a spraying device such as a nozzle. Then, when the slag in the converter is discharged to the port after the completion of the first blowing, the sediment is sprayed toward the slag surface in the port. At this time, nitrogen gas can be supplied to the nozzles and supplied together, and the jetting rate is 4 bar or more.

When the sediment containing flux is sprayed onto the surface of the slag, the sediment penetrates into the slag. At this time, since the slag discharged into the port is at about 1400 ° C, the gas is generated by sodium hydrogencarbonate (NaHCO 3) contained in the flux. This gas forms a plurality of holes or channels in the slag, and bubbles are rapidly discharged through the holes. As a result, the volume or volume of the slag is inhibited from increasing, and therefore slagging of the slag to the outside of the port can be suppressed or prevented (see Fig. 4).

When the slag disposal ends, the converter is erected again. Then, oxygen is re-blown (second blown) into the converter furnace line, and decarburization is performed to remove impurities such as carbon (C) from the charcoal. When the decarburization is finished, the molten steel is introduced by tilting the converter.

As described above, in the embodiment of the present invention, a flux having a high solubility in water is provided. When the slag is discharged into the port, the flux and the water are mixed and the sediment in the water or slurry state is injected toward the slag in the port. Therefore, according to the method of the present invention, since the flux is broken or dust is not generated as in the case where the flux of the briquetting type is inputted through the hopper as in the prior art, The slag soothing effect is higher than the conventional one. Thus, slagging can be more effectively suppressed or prevented when the slag is discharged to the port.

S100: Preparation of flux S200: Preparation of solvent
S300: Mixing of flux and water
S400: sedative injection

Claims (15)

As a flux that calms the slag generated in the steelmaking process,
A flux comprising sodium carbonate (Na ₂ CO ₃ ) and sodium sulfate (Na ₂ SO ₄ ). The method according to claim 1,
The flux further comprising sodium chloride (NaCl) in addition to the sodium carbonate (Na ₂ CO ₃ ) and the sodium sulfate (Na ₂ SO ₄ ). The method according to claim 1,
The flux having the same amount of the sodium carbonate (Na ₂ CO ₃ ) and the sodium sulfate (Na ₂ SO ₄ ) or the sodium sulfate (Na ₂ SO ₄ ) is more than the sodium carbonate (Na ₂ CO ₃ ). The method of claim 2,
Wherein the content of the sodium carbonate (Na ₂ CO ₃ ) and the sodium sulfate (Na ₂ SO ₄ ) is larger than the content of the sodium chloride (NaCl). The method of claim 2,
The sodium carbonate (Na ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ) and sodium chloride (NaCl) are obtained from the desulfurizing dust generated during the desulfurization of the exhaust gas generated during the production of the sintered ores. A sediment comprising the flux of any one of claims 1 to 5 and a solvent in which the flux is dissolved, in the form of a solution or slurry. The method of claim 6,
Wherein the solvent comprises water. A process of blowing oxygen into the furnace inside and refining the furnace;
Disposing the slag in the converter into a port disposed outside the converter after completion of the scouring; And
Injecting a sediment into the slag in the port;
/ RTI >
In the step of injecting the sedative,
Mixing the flux and the solvent to prepare a sediment in which the flux is dissolved; And
Spraying the sedative toward the slag;
And a heating means for heating the molten iron. The method of claim 8,
And mixing the flux and the solvent so that the sedative is in a solution or slurry state. The method of claim 9,
Wherein the mixing ratio of the flux to the solvent is from 10: 1 to 2: 1 in mixing the flux and the solvent. The method according to any one of claims 8 to 10,
Wherein the solvent comprises water. The method according to any one of claims 8 to 10,
Molten iron refining method in which the flux is included the sodium carbonate (Na ₂ CO ₃₎ and sodium sulfate (Na ₂ SO _4). The method of claim 12,
Wherein the flux further comprises sodium chloride (NaCl). 14. The method of claim 13,
Wherein said sodium carbonate, sodium sulfate, and sodium chloride are obtained from a desulfurizing dust generated during desulfurization of an exhaust gas generated during the production of sinter. The method according to any one of claims 8 to 10,
In the spraying of the sediment with slag, nitrogen is injected together and sprayed.

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