KR101538845B1 - Method for prodution for part reduced iron with caronaceous material incorporated - Google Patents

Abstract

The method for producing a partially burnt partly reduced iron according to an embodiment of the present invention includes the steps of preparing a mixture by mixing an iron raw material, a coal raw material and a binder, a step of compacting the mixture to produce a briquette, , And the residual carbon content of the partially reduced iron after the reduction step is 4 to 10% by weight.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing a partially reduced iron having a carbonaceous material,

The present invention relates to a method for producing partially reduced iron using iron raw materials and carbonaceous materials, and more particularly, to a method for producing a partially carbonaceous partially reduced iron containing residual carbon in order to maximize its use effect in a blast furnace.

The steel industry is one of the oldest industries that has come along with the development of mankind as a core industry that supplies basic materials to all industries such as automobile, shipbuilding, home appliance, and construction. Steel mills, which play a pivotal role in the steel industry, manufacture molten iron, which is a molten iron by using iron ore and coal as raw materials, and then manufacture steel from these to supply them to each customer.

Currently, about 60% of the world's iron production is produced from the blast furnace, which was developed from the 14th century. The blast furnace method is a method of manufacturing molten iron by adding sintered iron ore and cokes produced from bituminous coal as raw materials, blowing hot air and reducing iron ore to iron.

Since the blast furnace process, which is a type of molten iron production facility, requires a raw material having a certain level of strength or more and a particle size capable of ensuring ventilation in the blast furnace, as described above, it is used as a fuel and a reducing agent Carbon source, which depends on coke treated with specific cokes, and the iron source is mainly dependent on a series of masses and sintered ores that have undergone the process.

Accordingly, since the present blast furnace method necessarily involves a raw material pre-treatment facility such as a coke making facility and a sintering facility, it is necessary not only to construct an additional facility other than the blast furnace, There is also a problem that the investment costs are consumed in a large amount and the manufacturing cost is rapidly increased.

Also, in order to smooth the flow of reducing gas in the blast furnace, the sintered ore which made the iron ore into a lump state and the coke which is made into the lump state by charging the analytical carbon are charged.

However, the contact area of the reducing gas per unit volume of the sintered ore in the bulk state is extremely small as compared with the iron ore, and even after the reduction in the blast furnace is completed, the contact area with the carbon is small and it is difficult to permeate the carbon into the reduced iron. Therefore, the sintered ores have a high melting point, so they require a lot of energy to melt and have a fundamental problem that the production speed of the molten iron is slow.

To solve these problems, in the case of direct reduced iron (DRI), which has conventionally developed and used direct reduced iron (DRI), a process of manufacturing a pellet of a minute iron ore and inducing a reduction in a rotary hearth furnace Has come. However, these processes have a production volume of 150,000 to 500,000 tons per year, which is limited to mass production and the reduction rate is 95%, which is used as an electric furnace raw material.

Particularly, when partially reduced iron is used in a blast furnace, it is known that it significantly contributes to the stabilization of the sulfur content by significantly reducing the reduction ratio in the blast furnace, improving the productivity, and improving the air permeability in the high temperature portion of the blast furnace.

However, the residual carbon content in the conventional partially reduced iron is about 1 to 4% by weight, which means that carbon in the reduced iron is only solidified in the reduced iron by carburization. In this case, there has been a problem that the effect of stabilizing the sulfur content by the improvement of the productivity and the improvement of the air permeability exerted in the blast furnace is insignificant.

Patent Publication No. 10-2010-0132678 Patent Publication No. 10-2011-0069634

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is an object of the present invention to provide a partially reduced reduced iron having a carbon content retained in a partially reduced iron, And a manufacturing method thereof.

In order to accomplish the above object, the present invention provides a method for manufacturing a partially burnt partly reduced iron according to an embodiment of the present invention includes the steps of preparing a mixture by mixing an iron raw material, a coal raw material, and a binder, And a step of reducing the briquettes in the open reduction furnace, wherein the residual carbon content of the partially reduced iron after the reduction process is 4 to 10% by weight.

The reduction temperature of the reducing furnace may be 1000 to 1200 ° C, the oxygen concentration may be 15% or less, and the reduction time may be 10 to 30 minutes.

The carbonaceous material may be contained in an amount of 20 to 30% by weight, and the particle size thereof may be 1 mm or less.

The iron material may include at least one selected from iron oxide, iron oxide dust and sludge generated in a steel process.

The carbonaceous material may include at least one of coal and dust produced in a steel process.

The binder is an organic binder containing at least one of a hydraulic binder containing at least one of Portland cement, slaked lime and quicklime, or at least one of molasses, tar and starch, and may be contained in an amount of 1 to 3% by weight.

During the reduction process, the by-product gas of the steel mill is blown into the cooling zone of the open reduction reactor to cool the partially reduced iron, and the gas generated in the cooling zone can be blown into the combustion furnace.

According to the manufacturing method of the partially embedded reduced iron of the present invention, when the partially reduced iron is used as the raw material in the blast furnace because the remaining carbon is contained in a certain amount or more in the partially reduced iron, the productivity in the blast furnace is improved by improving the air permeability in the blast furnace .

FIG. 1 is a view showing a manufacturing process of a partially burnt carbon partially embedded iron according to an embodiment of the present invention.
2 is a view schematically showing a configuration of a reducing furnace according to an embodiment of the present invention.
FIG. 3 is a graph showing the reduction ratio according to the carbonaceous content in the carbonaceous internal briquettes at each oxygen partial pressure.
4 is a graph showing the residual carbon content in the partially reduced iron according to the carbonaceous content in the carbonaceous internal briquettes at each oxygen partial pressure.
5 is a graph showing the residual carbon content in the partially reduced iron according to the reduction time at each oxygen partial pressure.
FIG. 6 is a graph showing a change in the fusing zone width of a conventional partially reduced iron and a partially reduced iron having a built-in carbonaceous material according to the present invention. FIG.
FIG. 7 is a graph showing a change in the blast furnace width depending on the carbon content in the partially reduced iron according to the present invention. FIG.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, a method for manufacturing a partially embedded reduced iron according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

The inventors of the present invention have confirmed that the effect is increased by increasing the residual carbon content in the partially reduced iron by repeatedly investigating to maximize the effect of the partially reduced iron in the blast furnace. In order to increase the residual carbon content, And the reduction conditions in the open reduction reactor should be set up, thereby leading to the present invention.

FIG. 1 is a schematic view illustrating a method of manufacturing a partially built-in partially reduced iron according to an embodiment of the present invention.

A method of manufacturing a partially embedded reduced iron according to an embodiment of the present invention comprises the steps of: preparing a mixture by mixing an iron raw material, a coal raw material and a binder; Compacting the mixture to produce briquettes; And reducing the briquettes in the open reduction furnace.

As shown in FIG. 1, iron raw materials, carbon materials and binders are prepared in the iron raw hopper 1, the carbonaceous material hopper 2 and the binder hopper 3, respectively, and then mixed in the mixer 5 uniformly. In the case of carbonaceous material, it may be pulverized in the particle size separator 4 and then injected into the mixer 5.

Hereinafter, components to be mixed will be described in detail.

Carbonaceous material is effective in maintaining the temperature required for liquid slag and inducing reduction. In particular, it corresponds to an important component for determining the carbon content remaining in the partially reduced iron. In the present invention, in order to maintain the residual carbon content in the partially reduced iron at a certain level, it is preferably 20 to 30% by weight. When the content of the carbonaceous material is less than 20%, it is difficult to contain the remaining carbon content in the partially reduced iron at a content of 4% or more, and it is difficult to expect the improvement of the productivity by improving the air permeability in the blast furnace. When the content of the carbonaceous material exceeds 30% As the carbonaceous material increases, the strength of the partially reduced iron decreases, while the effect of the increase of the carbon content of the partially reduced iron increases with the increase of the carbonaceous material. In addition, the carbonaceous material may include at least one of coal and dust produced in a steel process.

The binder is chemically bonded between the carbonaceous material and the iron raw material to increase viscosity and adhesion. The content of the binder is preferably 1 to 3% by weight. When the content of the binder is less than 1% by weight, the effect of increasing viscosity and tackiness is insignificant. When the content of the binder is more than 3% by weight, the amount of slag in the briquet is increased and the basicity of the briquet is increased There is a problem that the inefficient operation of the blast furnace can be caused and the production cost is increased.

The binder may be a hydraulic binder containing at least one of Portland cement, slaked lime and quicklime, or an organic binder including at least one of molasses, tar and starch.

The iron raw material may be at least one selected from iron oxide, iron oxide dust and sludge generated in the iron-making process, and it is preferable to use a minute powder having an average particle diameter of 0.1 mm or less.

Impurities that are not intended from the raw material or the surrounding environment may be mixed in the other conventional manufacturing processes, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they will be known to those skilled in the art in the course of ordinary manufacture.

After the raw materials are mixed in the mixer 5, a mixture of the iron raw material, the carbonaceous material and the binder is compacted in a molding machine to produce briquettes. At this time, it is preferable that the compacting temperature in the molding machine 6 is set at room temperature. For example, when the compacting is performed in the molding machine 6 having a pair of rolls, it may be manufactured in the form of briquettes.

Thereafter, the reduction process is performed in the open reduction furnace 7. The reduced briquettes are made of partially reduced iron containing carbonaceous material after cooling in the reduction furnace (7). The cooling portion of the reducing furnace 7 is cooled by the by-product gas of the steel mill and the re-use of the briquet can be prevented.

The structure of the reducing furnace 7 according to one embodiment of the present invention is shown in Fig.

2, the reduction furnace 7 may include a drying table 71, a preheating table 72, a reduction table 73, a cooling table 74, and an ignition furnace 75.

The briquettes made in the molding machine 6 contain a large amount of water, which is a compact material, so that a thermal shock may cause a break in heat supply. It can be prevented from passing through the drying table 71. At this time, the heating gas supplied to the drying stand 71 can be exhaust gas discharged from the reduction stand 73.

The briquettes that have passed through the drying table 71 may be passed through the preheating stage 72 to help reduce them on the reduction table 73. The heating gas supplied to the preheating column 72 may be an exhaust gas discharged from the reduction column 73 as the drying table 71.

The briquettes in the reduction unit (73) have a low flow resistance and a fast flow rate of hot air through the briquettes and have sufficient heat during the reduction. Thus, the partially reduced iron is obtained through the cooling zone.

The gas generated in the cooling zone moves to the ignition furnace, and external air is supplied to the ignition furnace when combustion is required.

The cooling zone is formed with an inert atmosphere by injecting a by-product gas such as COG gas (Coke Oven Gas) to prevent reoxidation of the briquettes, so that a good reduction ratio can be obtained in the reduction zone (73).

In the present invention, important reaction conditions that allow the residual carbon content in the partially reduced iron to be maintained at 4% or more are the reduction temperature, the reduction time, and the oxygen concentration.

The reduction temperature of the reduction furnace 73 in the reduction furnace 7 is preferably 1000 to 1200 ° C. In order to perform the partial reduction of the briquettes on the surface layer, it is necessary to maintain the temperature at 1000 ° C or higher. When the temperature is higher than 1200 ° C, the melt may be generated due to the low melting point oxide and the process may become difficult to proceed.

The oxygen concentration in the reducing furnace 7 is preferably controlled to 15% or less. If the oxygen concentration exceeds 15%, the carbonaceous materials present in the briquettes may be oxidized and the remaining carbon content in the partially reduced iron may not be contained in more than 4%.

It is preferable that the reduction time is appropriately maintained in accordance with the reduction temperature and the oxygen concentration. Concretely, the reduction time is preferably 10 to 30 minutes.

In order to secure the degree of reduction of the partially reduced iron, a time of 10 minutes or more is required, and in the case of exceeding 30 minutes, the increase of the reduction degree is insignificant and the production cost can be increased.

Hereinafter, the present invention will be described with reference to experimental examples.

Briquettes were prepared by adding 5 ~ 30% carbonaceous materials to investigate the reduction rate and carbon consumption in the reducing furnace according to the amount of coal added to the carbonaceous internal briquettes. Fine iron ore with a grain size of 0.1mm or less was used as iron raw material, and granular coal of 1mm or less was used after crushing general coal for metallurgy. The reduction ratio of each briquette according to the oxygen partial pressure after reduction for 20 minutes in the reduction furnace at 1200 DEG C is shown in Fig. The remaining carbon content in the partially reduced iron after reduction is shown in Fig. As shown in FIG. 3, it can be seen that the reduction rate of the initial carbon bearing briquet increases with the increase of the carbonaceous content at the same oxygen partial pressure, and the reduction rate decreases as the oxygen partial pressure in the reducing furnace increases. Also, as shown in FIG. 4, it can be seen that the residual carbon content in the partially reduced iron after the reduction increases with the increase of the initial carbon material content at the same oxygen partial pressure.

5 is a graph showing the change in the residual carbon content in the partially reduced iron according to the reduction time in the reducing furnace at each oxygen partial pressure. As shown in FIG. 5, the residual carbon content in the partially reduced iron decreases with the reduction time. 3 to 5, in order to increase the residual carbon content in the partially reduced iron while maintaining the reduction rate of the partially reduced iron at a certain level or more, the reduction time depends on the content of the carbonaceous material added in the initial briquetting and the oxygen partial pressure in the reducing furnace It can be seen that this is a process condition.

Sintered and partially reduced iron, which is a conventional blast furnace charge, and partially reduced iron with a carbonaceous material were measured using a blast furnace system to measure the changes in the width of the fusion zone in the blast furnace, and the results are shown in the figure. The blast furnace width can be represented by the difference between the temperature (Td) at which the charge is completely reduced and the iron is melted and dropped and the temperature (Ts) at which the charge starts to soften. In the blast furnace, As a phenomenon that occurs according to the melting reaction, when the width is narrowed, the air permeability in the blast furnace is improved, so that the operation is facilitated and the productivity is improved. As shown in FIG. 6, it can be seen that when the sintering is compared with 100% of the sintered ore and 90% is partially mixed with 10% partially reduced iron, the fusing zone width becomes narrower. In addition, when 10% of the partially reduced iron containing the carbonaceous material according to the present invention is mixed in 90% of the sintered ores, it can be confirmed that the fusing belt width is remarkably lowered.

From these results, it can be seen that the use of the partially reduced iron with the carbonaceous material in the blast furnace greatly improves the effect of reducing the welding width of the partially reduced iron without the carbonaceous material and the existing charge.

FIG. 7 shows the width of the fused zone according to the residual carbon content in the partially reduced iron according to the present invention, and the effect is remarkably exhibited when the residual carbon content is 4% or more. However, as the residual carbon content increases, the effect is improved. If the carbon content exceeds 10%, it is difficult to process the briquettes by forming the briquettes, and since the width of the fusing zone is less than the increase of the residual carbon content The residual carbon content in the invention is preferably from 4 to 10%, more preferably from 4 to 7%.

From the above results, it can be seen that the use of the partially reduced iron with the carbonaceous material is effective when the partially reduced iron is charged in order to facilitate the operation in the blast furnace and to improve the productivity.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

1: Iron feed hopper 2: Carbon feed hopper 3: Binder hopper
4: particle size separator 5: mixer 6: molding machine
7: Reduction furnace 8: Partially reduced iron 71:
72: Yes Tropical 73: Reduction zone 74: Cooling zone
75: by ignition 76: by-product gas

Claims (7)

20 to 30% by weight of carbonaceous material, 1 to 3% by weight of binder, the balance iron raw material and unavoidable impurities to prepare a mixture;
Compacting the mixture to produce briquettes; And
And reducing the briquettes in the open reduction reactor,
The reduction temperature in the reduction step is 1000 to 1200 ° C, the oxygen concentration is 15% or less, the reduction time is 10 to 30 minutes,
Wherein the residual carbon content in the partially reduced iron after the reduction step is 4 to 10 wt%.
delete The method according to claim 1,
Wherein the carbonaceous material has a particle diameter of 1 mm or less.
The method according to claim 1,
Wherein the iron raw material comprises at least one selected from the group consisting of iron oxide, iron oxide dust generated in a steel process, and sludge.
The method according to claim 1,
Wherein the carbonaceous material comprises at least one of coal and dust generated in a steel process.
The method according to claim 1,
Wherein the binder is an organic binder comprising at least one of a hydraulic binder containing at least one of Portland cement, slaked lime and quicklime or molasses, tar and starch.
The method according to claim 1,
Wherein the by-product gas of a steel mill is blown into a cooling zone of an open reduction reactor to cool the partially reduced iron during the reduction process, and the gas generated in the cooling zone is blown into the ignition furnace.

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