KR20130062714A - Method for manufacturing iron-based powders - Google Patents

Abstract

PURPOSE: A method for manufacturing iron-based powder is provided to utilize molten iron in manufacturing the powder in order to highly maintain sulfur content inside the molten steel without feeding an extra substance containing sulfur, thereby lowering the surface tension of the molten steel to which water is jetted and increasing the molding strength of the powder. CONSTITUTION: A method for manufacturing iron-based powder includes: a step of feeding iron-based molten steel formed by mixing, melting, and refining molten iron and iron-based scrap, which are manufactured through an iron making process, in a steelmaking furnace to a tundish; and a step of jetting water to the molten steel discharged from a nozzle connected to the tundish. After tapped, the molten iron is charged into the steelmaking furnace without desulfurization. The molten steel formed by mixing the molten iron and the iron-based scrap includes 20-90 wt% of the molten iron. [Reference numerals] (AA) Molten steel(material); (BB) Iron-based scrap; (CC) Converter(steel making); (DD) Ladle; (EE) Water-injection(powder production)

Description

Manufacturing method of iron-based powder {METHOD FOR MANUFACTURING IRON-BASED POWDERS}

The present invention relates to a method for producing iron-based powder, and more particularly to a method for producing iron-based powder by utilizing molten iron and iron-based scrap.

Recently, with the development of the sintering parts industry having a complicated shape required for automobiles and machines, the amount of iron-based powders used as raw materials is rapidly increasing.

Sintering parts are filled with iron powder, which is a raw material, inside a mold having a shape of a manufactured product suitable for the purpose, and then compression-molded by applying a high pressure of 4-7 ton / cm ² , and sintered at high temperature to give physical and mechanical properties. Treatment is performed to obtain a high density sintered body.

In particular, in order to manufacture automotive sintered parts, the powder itself should be of excellent quality so that a high density sintered body such as proper particle size, flow rate, apparent density, molding density, and high cleanness can be manufactured.

Unlike the reduced iron powder, iron-based powder (iron powder) manufactured through the water spray process has no phenomenon that pores remain in the place where the oxide is reduced in the powder during the reduction process, so that almost no internal pores exist. It is known to be suitable for the production of high-density sintered parts because the molding density of is higher than 0.5 g / cm 3 compared to the reduced iron powder.

In addition, in the manufacture of iron-based powder to maintain the high cleanness of the iron-based powder by minimizing impurities such as carbon (C), oxygen (O), nitrogen (N), sulfur (S), phosphorus (P) that adversely affects the formability It is very important.

Along with the excellent qualities such as high cleanliness and high molding density, another important requirement for iron-based powders is the economics of the manufacturing process.

Conventionally, scrap metal was re-dissolved in an arc electric furnace to undergo molten steel through a refining process including oxygen scavenging such as decarburization and delineation, and then iron powder was manufactured by a water spraying process.

However, in the prior art, since the surface tension of molten steel to be sprayed is high, the shape of the powder tends to be spherical when the molten steel is powdered in the water spraying process. There was a problem of unwanted breakage.

The present invention has been made to solve these problems, the object of the present invention,

First, it provides a method to obtain molten steel with a more even component ratio than the conventional by melting the molten iron in a state in which the molten iron is mixed in a predetermined ratio to the existing iron-based scrap,

Second, by eliminating the desulfurization treatment during the molten iron preliminary treatment in the conventional steelmaking process to provide a method for maintaining a high sulfur content of molten steel sprayed water, thereby keeping the surface tension of the molten steel sprayed water lower than conventional,

Third, to control the sulfur content that adversely affects the molding of the iron-based powder, after the thermal spraying after water spraying without a separate desulfurization process, or to repeat the reduction heat treatment to control the sulfur content to a predetermined level or less or the reduction heat treatment It is to provide a method of adding a post-desulfurization treatment.

In order to achieve the above object, the iron-based powder manufacturing method according to an embodiment of the present invention, the molten iron and iron-based scrap produced by the steelmaking process by mixing in the steelmaking step to provide a molten and refined iron-based molten steel in the tundish , And water spraying on molten steel discharged through the nozzle connected to the tundish.

The molten iron may be charged into the steelmaking furnace together with the iron-based scrap without desulfurization treatment after the ship.

The molten iron in the molten steel mixed with the molten iron and the iron scrap may be in the range of 20 to 90%.

The steelmaking furnace may be any one of a converter, a furnace and an electric furnace.

The temperature range of the molten iron before charging in the steelmaking furnace may be 1,250 ℃ ~ 1,450 ℃, the content of sulfur (S) may be 0.005wt% ~ 0.1wt%.

The method of manufacturing the iron-based powder may further include adding a sulfur-containing material to the molten steel so that the content of sulfur (S) contained in the molten steel is 0.1 wt% to 0.2 wt% before it is provided to the tundish. Can be.

The iron-based powder manufacturing method may further include the step of dehydration, drying and reducing heat treatment of the iron-based powder produced by the water yarn.

The reduction heat treatment may be performed by reacting the iron-based powder, which is separated into droplets by the water yarn and cooled, in a reducing atmosphere of 600 ° C to 1,200 ° C.

After the reduction heat treatment, if the average content of sulfur (S) of the iron-based powder exceeds 0.01wt%, the reduction heat treatment may be repeated or a separate desulfurization treatment may be performed.

The iron-based powder may be pure iron powder or alloyed iron powder.

The method for producing an iron-based powder according to the present invention has the following effects.

First, the present invention, unlike the prior art using only iron-based scrap in the production of iron-based powder, by mixing the molten iron in the liquid state with iron-based scrap to produce the iron-based powder, it is possible to provide a powder of excellent quality and to reduce the manufacturing cost .

Second, since molten iron is used in powder production, it is possible to maintain a high sulfur content in molten steel without supplying a separate sulfur-containing material, thereby lowering the surface tension of molten steel that is sprayed with water, thereby increasing the molding strength of the iron-based powder.

Third, iron-based scraps containing predetermined alloy components can still be utilized in the production of alloyed Fe powders rather than pure Fe powders, so that a process of separately adding materials containing predetermined alloy components can be omitted. have. That is, the advantage of using molten iron in the powder production and the advantage of utilizing iron-based scrap can be obtained at the same time.

Fourth, the effort to maintain even quality is reduced by reducing the amount of iron-based scrap, and the supply of sulfur-containing materials and / or desulfurization treatment can be omitted, and the iron-based powder can be produced very economically.

1 is a view schematically showing a manufacturing process of iron-based powder using molten iron and iron scrap according to an embodiment of the present invention.
2 is a view schematically illustrating a process of water spraying on molten steel discharged from a nozzle connected to a tundish.

Hereinafter, a method of manufacturing iron-based powder using molten steel according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a view schematically showing a manufacturing process of iron-based powder using molten iron and iron scrap according to an embodiment of the present invention.

As shown in Figure 1, the iron-based powder manufacturing method according to an embodiment of the present invention by mixing the molten iron and iron scrap produced by the steelmaking process in the steelmaking furnace to provide a molten and refined iron-based molten steel to the tundish step; And spraying water on molten steel discharged through the nozzle connected to the tundish.

Here, the iron making process is a process for manufacturing molten iron using a conventional iron making equipment, and includes a blast furnace operation or a Finex melt reduction process (FINEX) and a corex melt reduction process (COREX).

The chartered boat is transported by the charter truck and charged into the steelmaking furnace. The content of the main components of the chartered molten iron is 4 wt% or more of carbon (C), 0.1 to 1 wt% of silicon (Si), 0.1 to 0.5 wt% of manganese (Mn), 0.06 to 0.2 wt% of phosphorus (P), and sulfur (S) 0.005 to 0.1wt%, chromium (Cr) 0.1wt% or less, titanium (Ti) 0.1wt% or less, vanadium (V) 0.1wt% or less, copper (Cu) 0.01% or less.

The temperature of the molten iron during charging of the steelmaking furnace may range from 1250 ^o C to 1450 ^o C.

Unlike the present invention, in the continuous casting process for manufacturing slabs and the like in general, the molten iron is added to a ladle before charging the molten iron into the converter, and the sulfur is 0.005wt% by the molten iron preliminary treatment (including desulfurization). To control below, this process takes about 45 minutes and the molten iron temperature drops to a maximum of 50 ^o C.

Here, the desulfurization treatment refers to a process of removing sulfur components contained in the molten iron by adding quick lime or the like to the molten iron charged into the ladle and stirring the same.

However, the present invention does not necessarily require the molten iron preliminary treatment step to be subjected to the general steelmaking process. That is, since sulfur contained in the molten iron does not have to be removed during the pretreatment process, the above temperature drop can be prevented and the process time can be shortened. In addition, sulfur serves to reduce the surface tension of the molten steel to have a non-spherical irregular shape of the powder when the molten steel is powdered in the water spraying process to be described later.

On the other hand, the present invention, in addition to the molten iron is charged into the steel scrap. Here, the source of iron-based scrap is mainly used such as scrap generated in the continuous casting process, scrap generated from hot rolling and cold rolling, and scrap with a total sum of alloy components generated in the recycling process of automotive cold rolled steel sheet of 0.5wt% or less. In the case of manufacturing iron alloy powder containing a specific component system (Ni, Cr, Mn, Mo), it is possible to mix and charge the scrap containing 0.5 to 5wt% of the corresponding component.

Subsequently, the molten iron and iron scrap scraped in the steelmaking furnace are dissolved and refined. In other words, the steelmaking process is carried out to reduce the carbon content and remove impurities by refining impurities such as carbon, silicon, manganese and phosphorus contained in molten iron and iron scrap. The steelmaking furnace may include a converter, an open hearth furnace, an electric furnace, or the like.

The electric furnace may be a resistance furnace, an arc furnace, an induction furnace and the like, but the present invention is not limited thereto.

The ratio of molten iron in the molten steel mixed with the molten iron and the iron-based scrap may be adjusted in a range of 20 to 90 wt%.

When producing pure Fe powder, it is advantageous to increase the molten iron ratio, and alloyed Fe which requires a specific alloying component such as manganese (Mn), nickel (Ni), copper (Cu), and chromium (Cr) In preparing powders it is advantageous to increase the proportion of scrap.

In this steelmaking process, the steel is preferably refined to molten steel in the range of 0.001 to 0.1 wt% of carbon (C) and 0.001 wt% to 0.02 wt% of phosphorus (P) through oxidation reaction for 30 to 60 minutes. do.

In this case, the reason for maintaining the carbon content of the molten steel at 0.001 ~ 0.1wt% is that when the carbonization of molten steel powdered when the carbon (C) content is lower than 0.001wt%, the FeO oxide layer on the surface of the powder immediately after the water spraying This is because about 5 ~ 15㎛ occurs in the subsequent reduction heat treatment process, the required time, reducing gas consumption is increased, productivity is lowered and manufacturing costs are increased.

In addition, when the carbon (C) content is higher than 0.1wt%, even after the reduction heat treatment step, carbon in the powder is not completely removed, thereby forming carbides, thereby decreasing the formability of the powder by increasing the hardness value of the powder.

In addition, the reason for maintaining the content of phosphorus (P) in the molten steel at 0.001 ~ 0.02wt% is that the oxidation reaction time is more necessary using the double-slag method in order to lower the phosphorus component to 0.001wt% level. This is because the electric furnace process is longer, and if it is higher than 0.02wt%, brittleness appears in the final product, resulting in a decrease in product life.

On the other hand, the present invention may further comprise the step of adding a sulfur-containing material to the molten steel so that the content of sulfur (S) contained in the molten steel is 0.1wt% ~ 0.2wt%.

By adding a substance that increases the content of sulfur in the molten steel, the viscosity of the molten steel is reduced (the fluidity of the molten steel is increased), so that the shape of the powder produced by the process of spraying high pressure water onto the subsequent molten steel, that is, the falling molten steel is spherical. In order to have an irregular shape rather than to increase the molding strength of the molded body when the powder is compressed and formed.

Here, as the material capable of increasing the content of sulfur, ferro-sulfur alloys containing sulfur, such as ferro-sulfur (FeS) may be used, and the ferro-alloy may be introduced into a steelmaking furnace, or may contain refined molten steel in a ladle. It may be added to the ladle before feeding to the tundish, or may be fed directly to the tundish.

Next, the molten steel subjected to the oxidation reaction in the steelmaking furnace is pulled out to the ladle in the temperature range of 1550 ^o C ~ 1750 ^o C, and the molten steel at the temperature of 1530 ^o C ~ 1700 ^o C in the ladle of 100kg / min ~ 3ton / min The molten steel may be dropped into the tundish under the ladle at a discharge rate, and the molten steel may be dropped into the water spray process chamber under the circular nozzle (for example, a ceramic orifice) having an inner diameter of 10 mm to 40 mm located under the tundish.

In this case, if the molten steel in the ladle is less than 1530 ^o C, the molten steel will solidify and the process will not proceed any longer. If it exceeds 1700 ^o C, the ladle refractory and tundish refractory will be overloaded, making operation very dangerous. Can be.

In addition, if the molten steel discharge rate is lower than 100 kg / min, the productivity is lowered and the cost is raised. In addition, it is very difficult to process molten steel having a capacity of 10 tons or more. If the molten steel discharge rate is higher than 3 ton / min, Since a large amount of water is required, the scale of the device as a whole increases exponentially, which leads to an excessive investment cost.

FIG. 2 is a view schematically illustrating a process of manufacturing iron powder by spraying high pressure water on the molten iron steel discharged through a nozzle connected to a tundish.

Molten steel flowing into the water spray process chamber through the nozzle is separated into droplets having a size of 500 μm or less due to a collision with water sprayed at a pressure of 50 to 300 bar through a nozzle for spraying high pressure water located above the chamber. The droplets are quenched by the cooling water and the sprayed water, which is 20 to 80% filled in the chamber, and the ratio of 150 μm (100 mesh) or less is powdered to 80 to 95%. At this time, since water and iron are in direct contact with each other at a high temperature, the surface is covered with an oxide layer.

If the pressure of the high pressure water is lower than 50bar, the surface roughness of powder is lowered and more than 80% of powder of 150m or less cannot be obtained, and if the pressure is 300bar or higher, the average particle size of powder is reduced, so that the powder of 100mesh or less of the desired size range is 80% or more. 95% or less) powder cannot be obtained, resulting in low yield.

Then, the powder obtained as described above is separated from the process water and the cooling water in the chamber, and then dried to a water content of 0.1 wt% through dehydration and drying treatment, and then flowing a reducing gas including hydrogen at a temperature of 600 to 1,200 ^o C. Heat treatment is carried out to below 0.2wt% oxygen.

By the reduction heat treatment as described above it is managed so that the average content of sulfur (S) in the powder is 0.01wt% or less. When the average content of sulfur in the powder exceeds 0.01wt%, the reduction heat treatment may be repeatedly performed or a separate desulfurization treatment may be performed to increase the formability of the powder.

Thereafter, the powders are subjected to a pulverizing step, a classification step and a mixing step to control the average size of 50 to 100 탆 and the ratio of less than 45 탆 to 40% or less and the ratio of less than 150 탆 to 80 to 95% .

When the particle size distribution of the powder immediately after the water jetting process is 100 to 95% or less, the amount of the powder to be lost in the subsequent process is minimized and the powder yield can be increased.

If it is less than 80%, the powder larger than 100mesh exceeds 20%, and the powder yield falls below 80%, which is not preferable because unnecessary work such as scraping large powder is required. The particle size is lowered to the level of 50㎛, the proportion of -325mesh powder exceeds 40%, and the powder fluidity is deteriorated (30sec / 50g or more), and the powder loading rate is lowered in the mold during the molding process, resulting in poor productivity. Due to this, the density density region inside the molded body is generated.

In addition, the required molding pressure for the same density molded article is increased, so that a repetitive high pressure is applied to the mold, thereby reducing the mold life.

Hereinafter, the production method of the iron-based powder according to the present invention through the examples will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

≪ Example 1 >

The molten iron produced in the blast furnace was mixed with scrap in an electric furnace or a converter without preliminary molten iron treatment, and after melting and steelmaking, the molten steel was transferred to a tundish, and iron-based powder was manufactured by using a high pressure water spray device.

The molten steel is applied to the oxidation refining process in the converter as a process for controlling from the components of the molten molten iron with a high carbon content produced through the iron making process.

In order to specifically calculate the cost reduction effect that can be generated by applying the present invention, iron-based powders using iron-based molten steel according to the present invention and iron scraps according to the prior art were re-dissolved in an arc electric furnace to produce iron-based powders.

The molten iron produced in the blast furnace is mixed with scrap to oxidize and refine carbon, silicon, phosphorus, etc. in the converter to obtain molten steel, load it into a tundish, and drop the molten steel through the nozzle, To prepare a powder to calculate the cost and total cost according to the process is shown in Table 1.

In addition, iron-based powder was manufactured through high-pressure water spraying process using molten steel obtained through steelmaking in an electric furnace after re-melting iron scrap, and the cost and total cost for each process are shown in Table 1 as comparative data.

When compared with the case of using the molten steel proposed in the present invention as a raw material, compared with the existing 100% iron scrap remelting process, the additional cost reduction effect such as the time required for the remelting process and the electric energy consumed for remelting is also very high. It is expected to be large.

Cost factor Raw material Steelmaking Powder manufacturing Sum Conventional
fair Iron scrap
100% Electric furnace
Steelmaking 36 million won / ton Water injection and post-treatment 68.6 million won / ton cost 550,000 won / ton 36 million won / ton 100,000 won / ton Invention Charter 80%
Steel scrap 20% converter
Steelmaking 2.4 million won / ton Water injection and post-treatment 61.4 million yuan / ton cost 490,000 won / ton 2.4 million won / ton 100,000 won / ton

As shown in Table 1, when the raw material mixture according to the present invention is applied to produce 1 ton of iron-based powder, a cost reduction effect of about 7.2 million won / ton can be expected as compared to a process for dissolving iron scrap.

In addition, the sensible heat of the molten iron can be utilized due to the mixing of the molten iron and the iron scrap, so as to minimize or eliminate the remelting process, various problems such as oxides, carbides, segregation, and heterogeneous composition that can be introduced from each process can also be controlled. It is also expected to be effective in the high quality of iron-based powders.

In addition, the high-purification effect of the impurities suppressed by the mixed use of the molten iron and the iron scrap of the iron-based powder prepared by applying the present invention was compared with the commercial iron-based powder prepared using the 100% iron scrap re-dissolution process.

The impurity items for comparative analysis focused on items such as carbon, oxygen, nitrogen, sulfur, phosphorus, and silicon, which have a great influence on formability, and were manufactured using a conventional process (Comparative Example 1, Comparative Example 2). And Comparative Example 3).

division Carbon (wt%) Oxygen
(wt%) nitrogen
(wt%) sulfur
(wt%) sign
(wt%) Silicon (wt%) Example 1 0.0019 0.0870 0.006 0.0015 0.005 0.0081 Comparative Example 1 0.0021 0.094 0.0097 0.0065 0.005 0.0088 Comparative Example 2 0.0023 0.16 0.008 0.0057 0.012 0.019 Comparative Example 3 0.0016 0.15 0.0067 0.0065 0.005 0.024

As shown in Table 2, when manufacturing the iron-based powder (Example 1) using the molten steel according to the present invention, impurities of the powder (Comparative Example 1, Comparative Example 2, Comparative Example 3) prepared by a conventional process It can be seen that iron-based powders of high cleanliness containing less or less than the minimum level were obtained in all impurity components compared to the component contents.

In particular, the gas impurity content of carbon, oxygen, nitrogen, etc., which is known to greatly affect the formability, is the minimum value of three kinds of powders according to the prior art in the case of the present invention, and is expected to have a great advantage in manufacturing high density sintered parts. do.

In order to verify the above effects, compression moldability was evaluated using a ring-shaped mold having an outer diameter of 40 mm and an inner diameter of 17 mm by mixing the powder according to the prior art and the iron powder according to the present invention with a lubricant. Before the molding, 0.5 wt% of zinc stearate was added to the iron powder as a solid lubricant and mixed under the same conditions for 15 to 20 minutes using a double cone mixer. The moldability evaluation was performed 15 times or more under the pressure of 600 MPa, and the density of the molded object was measured and the moldability comparison between powders was performed.

division Average Example 1 7.18 ± 0.01 Comparative Example 1 7.12 ± 0.02 Comparative Example 2 7.06 ± 0.02 Comparative Example 3 7.10 ± 0.03

As shown in Table 3, the density of the iron-based powder compact manufactured from the present invention is higher than the density of the powder compact manufactured by the prior art, which is 0.06 to 0.12 g / cm ³ . .

As the shrinkage rate is small in the manufacture of sintering parts using powder with excellent moldability, the defect rate can be lowered and the porosity inside can be lowered, thus making it possible to manufacture stressed parts requiring high strength and high toughness or the life of existing parts. Can be expected to increase the effect.

≪ Example 2 >

Five specimens were prepared to specifically calculate the effect of improving the quality of the iron powder that can be generated by applying the present invention. The five Psalms are:

First, molten iron manufactured in the blast furnace is not desulfurized, mixed with iron scrap in the converter, and then obtained by steelmaking process. The molten steel is pulled down to the ladle at the target temperature, and the molten steel falls through the orifice under the tundish. Iron powder was prepared by spraying water under high pressure, and reduction heat treatment was performed on the powder that had been dehydrated and dried. (Example 2, 0.05 wt% sulfur in molten steel)

Secondly, the molten iron produced in the blast furnace is not desulfurized, mixed with iron scrap in the converter, and then obtained by molten steel through a steelmaking process. It's fair. (Example 3, 0.2 wt% sulfur in molten steel)

Third, further desulfurization treatment was performed for Example 2. (Example 4)

Fourth, further desulfurization treatment was performed for Example 3. (Example 5)

Fifth, high-pressure water spraying, dehydration, drying, reduction heat treatment process is applied to molten steel which is re-dissolved in an arc electric furnace without mixing with molten iron for use as a comparative example and tapping into ladles and falling through the tundish lower orifice. The iron powder was prepared through. (Comparative Example 4, 0.01 wt% of sulfur in molten steel)

Table 4 below shows the components of the iron powder of the five samples. Since molten steel was manufactured so that the overall components of the five samples were similar, all of them showed similar component values. However, in Example 3, sulfur was slightly higher than other powders because sulfur-containing iron alloy was added to molten steel. It can be seen.

In the case of Comparative Example 4, the sulfur component was the lowest in the powder because no sulfur component was added to the molten steel.

division Carbon (wt%) Oxygen (wt%) nitrogen
(wt%) Sulfur (wt%) Phosphorus (wt%) Silicon (wt%) Example 2 0.0024 0.145 0.0075 0.0063 0.0082 0.0078 Example 3 0.0021 0.153 0.0064 0.0108 0.0078 0.0089 Example 4 0.0018 0.150 0.0065 0.0021 0.0062 0.0085 Example 5 0.0026 0.140 0.0069 0.0058 0.0068 0.0067 Comparative Example 4 0.0022 0.155 0.0072 0.0013 0.0070 0.0073

Table 2 shows the apparent density, fluidity, molding density (@ 600 MPa), and molding strength (@ 7.1 g / cm 3), which are commonly used as standard for evaluating powder characteristics, for five iron powders.

In the case of apparent density, Comparative Example 4 was the highest, which is considered to be because the shape of the powder is closer to the spherical form than the other four examples because of the low sulfur content in the molten steel. For the same reason, the flow rate was also the lowest in Comparative Example 4.

In the case of molding density, all values were similar when 600MPa pressure was applied, but Comparative Example 4 showed the lowest value in the molding strength, because the powder shape is close to the spherical shape, which means that the mechanical bonding force between the individual powders is decreased. do.

Forming strength values were high in Examples 3 and 5, where sulfur was added to molten steel, because the viscosity of molten steel was lowered due to the addition of sulfur. Judging.

In general, in the case of commercial powders, the molding strength is 30-40 MPa, and thus, in Examples 2 to 5, which are examples of the present invention, the molding strengths are similar to or higher than those of commercial powders. In Comparative Example 2, it can be seen that the value is much lower.

division Apparent density
(g / cm3) Flow rate
(sec / 50g) Forming density
(g / cm3) Forming strength
(MPa) Example 2 3.01 27.5 7.12 35 Example 3 2.97 28.1 7.11 43 Example 4 3.00 26.7 7.13 37 Example 5 3.02 27.4 7.15 40 Comparative Example 2 3.11 25.3 7.23 19

As shown in Table 5, it can be seen from the present invention that the molding strength of the iron powder compact manufactured in the molten iron exhibits a value two times higher than the strength of the powder compact manufactured by scrap re-dissolution.

This is because when the powder is manufactured under the same powder manufacturing conditions (water spray process, reduction process), when the molten steel is re-dissolved to obtain molten steel, if the sulfur content is low, the molding strength is lowered, which may cause breakage when transferring the molded product. do.

For this reason, it can be seen that in order to obtain iron powder having high forming strength during re-dissolution of scrap, it is necessary to additionally add sulfur component to dissolution, which increases the process cost.

On the other hand, if the 0.05 wt% sulfur component contained in the molten iron is applied to the water spraying process without removing the sulfur component separately, it is possible to obtain the molding strength and all the properties corresponding to the commercial powder without adding the sulfur component separately.

In the case of the prior art, in the case of using iron scrap (self-generating iron scrap) or a general iron scrap that is produced through the continuous casting process in the production of iron-based powder by re-dissolving in an arc melting furnace, oxygen, nitrogen, etc. in the atmosphere during the melting process It may be introduced, it may be necessary to control impurities such as slag, and may need to go through vacuum degassing and secondary refining process again.

On the other hand, as in the case of the present invention, in the case of using molten steel that has been refined in the direct steel making process, remelting, degassing, and secondary refining processes can be omitted, thereby achieving cost reduction due to shortening of the process. Since molten iron can be directly used, it is possible to control the influx of tramp elements that may occur when a large amount of scrap is mixed, thereby making it easy to manufacture high-clean iron powder having a low impurity content.

In addition, the present invention is not a technology that utilizes scrap as in the prior art, it is not necessary to adjust the sulfur content in the molten steel to an appropriate range by adding a certain amount of ferrous alloy containing sulfur components, which occurs during the ferrous alloy process. No additional heating process is required to compensate for the temperature loss.

The present invention utilizes a molten iron containing a certain amount of sulfur components without remelting the iron and adding ferroalloy, it is possible to manufacture iron powder very economically compared to the prior art.

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 shown by the following 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 construed as being included in the scope of the present invention. .

Claims (10)

Mixing molten iron and iron scrap produced in the steelmaking process in a steelmaking furnace to provide molten and refined iron molten steel to the tundish; And
And spraying water onto molten steel discharged through the nozzle connected to the tundish. The method of claim 1,
The molten iron is charged with the iron-based scrap without desulfurization after the wire is prepared in the steel production method, characterized in that the charging. 3. The method according to claim 1 or 2,
A ratio of the molten iron in the molten steel in which the molten iron and the iron-based scrap is mixed is 20 to 90 wt%. The method of claim 3, wherein
The steelmaking furnace is a method for producing iron powder, characterized in that any one of a converter, a furnace and an electric furnace. The method of claim 3, wherein
The temperature range of the molten iron before charging to the steelmaking furnace is 1,250 ℃ ~ 1,450 ℃, the content of sulfur (S) is a method for producing iron powder, characterized in that 0.005wt% ~ 0.1wt%. The method of claim 1,
Before providing to the tundish, further comprising the step of adding a sulfur-containing material to the molten steel so that the content of sulfur (S) contained in the molten steel is 0.1wt% ~ 0.2wt% Manufacturing method. The method of claim 1,
Dehydration, drying and reduction heat treatment of the iron-based powder produced by the water yarn further comprising the method of producing an iron-based powder. The method of claim 7, wherein
The reduction heat treatment is a method for producing iron powder, characterized in that by reacting the iron-based powder separated and cooled by the water droplets in a reducing atmosphere of 600 ℃ ~ 1,200 ℃. The method of claim 8,
If the average content of sulfur (S) of the iron-based powder after the reduction heat treatment exceeds 0.01wt%, the iron-based powder manufacturing method characterized in that for repeating the reduction heat treatment or performing a separate desulfurization treatment. The method of claim 1,
The iron-based powder is a method for producing iron powder, characterized in that the pure iron (pure Fe) powder or alloyed iron (alloyed Fe) powder.

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