KR101257054B1 - Method for manufacturing scrap of electric furnace using sludge - Google Patents

Abstract

Disclosed is a method of manufacturing scrap for an electric furnace using sludge. According to an embodiment of the present invention, by mixing different types of sludge to adjust the content ratio of the iron component and the carbon component; Crushing the mixed sludge to produce sludge powder; Adding water to the sludge powder so that the water content of the sludge powder is 15 to 20%; Manufacturing a scrap molded body by adding cement to the sludge powder; And it provides a method for producing a scrap for an electric furnace using sludge comprising the step of drying and baking the scrap molded body.

Description

Method for manufacturing scrap for electric furnace using sludge {METHOD FOR MANUFACTURING SCRAP OF ELECTRIC FURNACE USING SLUDGE}

The present invention relates to an electric furnace scrap manufacturing method using sludge that can utilize steel by-products.

Steel production processes produce iron and steel byproducts. Among the steel by-products, blast furnace sludge and converter dust have a high concentration of zinc. The zinc component penetrates into the eddies forming the blast furnace walls, eroding the walls. Such blast furnace sludge or converter dust can be recycled to the blast furnace after the zinc has been removed. In steelworks without zinc removal facilities, blast furnace sludge or converter dust can be solidified and landfilled.

Embodiments of the present invention, to provide a method for producing a scrap for an electric furnace using sludge that can be recycled in the electric furnace using the sludge generated in the steelmaking process.

According to one aspect of the invention, the step of adjusting the content ratio of iron and carbon components by mixing different types of sludge; Crushing the mixed sludge to produce sludge powder; Adding water to the sludge powder so that the water content of the sludge powder is 15 to 20%; Manufacturing a scrap molded body by adding cement to the sludge powder; And there is provided a method for producing a scrap for an electric furnace using sludge comprising the step of drying and firing the scrap molded body.

After mixing the other sludge, coke may be added to the mixed sludge to adjust the content of the carbon component.

The coke may be added so that the content ratio of the carbon component to the iron component is adjusted to 1.1 ~ 2.0.

In the method of manufacturing the scrap molded body, 6 to 9% of cement may be added to the sludge powder.

In the manufacturing of the sludge powder, blast furnace sludge and blast furnace dust sludge may be mixed.

In the preparation of the sludge powder, blast furnace main dust sludge, drainage terminal sludge and hot rolled sludge may be mixed.

The blast furnace dusty sludge, hot rolled sludge and drainage terminal sludge may be mixed in the same ratio.

According to embodiments of the present invention, the sludge generated in the steelmaking process can be recycled to the electric furnace.

1 is a block diagram showing a steelmaking process.
2 is a flow chart showing a method of manufacturing a scrap for an electric furnace using sludge according to an embodiment of the present invention.
3 is a flow chart showing a method of manufacturing a scrap for an electric furnace using sludge according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, an embodiment of a scrap manufacturing method for an electric furnace using sludge according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing a steelmaking process.

Referring to FIG. 1, iron ore is made of steel through a steelmaking process 10, a steelmaking process 20, and a rolling process 30. The iron making process 10 may include a process of manufacturing coke and a process of manufacturing pig iron.

Coke is produced by calcining limestone. Coke sludge is generated during the plastic working of coke. Coke is charged to the blast furnace along with iron ore.

In blast furnaces, molten iron and blast furnace sludge are produced as iron ore and coke are melted and reduced by hot air. When iron ore is melted and reduced to molten iron, gas and dust are released from the blast furnace to the outside. Gas and dust emitted from the blast furnace are collected by the dust collector. The sludge collected from the dust collector is called blast furnace dust sludge.

 The blast furnace column opening is formed in the blast furnace to discharge the molten iron and blast furnace sludge to the outside. The molten iron and blast furnace sludge are discharged through the blast furnace outlet. Dust and gas are released to the outside during the embarkation work. These dusts and gases are collected by a dust collector installed on the column. The dust collected by the column collector is called blast furnace columnar sludge.

As described above, in the steelmaking step 10, blast furnace sludge, blast furnace dust sludge, blast furnace columnar dust sludge and the like are generated.

The molten iron drawn out from the blast furnace is refined in the steelmaking process 20. In other words, the molten iron is reduced in the amount of carbon in the converter or electric furnace and impurities are removed. Hot-rolled sludge may be generated when the molten iron is refined in a converter or an electric furnace.

Steel refined in the steelmaking process 20 is made of steel while going through the rolling process (30).

In the above process, a large amount of water is used for cooling and the like. Such water can be discharged after workup in a drainage treatment plant. Wastewater treatment plants treat substances contained in the water. These materials are dried and then loaded into a yard or the like. This material is called drainage terminal sludge.

As such, many types of sludge are produced in the steelmaking process. The sludge contains various kinds of ingredients as shown in Table 1 below.

T-Fe (wt%) M-Fe (wt%) C (wt%) S (wt%) ZnO (wt%) Blast furnace sludge 29.1 1.3 20.2 1.2 4.4 Blast furnace dust sludge 24.0 Tr 41.4 0.3 Tr Blast furnace dust sludge 61.8 1.1 4.9 0.3 0.1 Drainage Sludge 4.9 Tr 23.5 0.7 0.8 Hot rolled sludge 61.3 1.1 4.9 0.3 0.1

In Table 1, T-Fe means the total amount of the iron component, M-Fe means the non-oxidized iron component, Tr means that the trace amount is extremely small.

Sludges contain large amounts of iron (Fe) and carbon (C). Since sludge has a small amount of unoxidized iron component (M-Fe), T-Fe will be referred to as iron component below.

Since the sludge contains a large amount of iron (T-Fe) and carbon (C), it is possible to recover the iron (M-Fe) by melting at a high temperature. For example, blast furnace sludge contains about 29 wt% of iron and 20 wt% of carbon, and may be melted at a high temperature. At this time, the reaction formula is as follows.

C + CO ₂ → 2CO

3Fe ₂ O ₃ + CO → 2Fe ₃ O ₄ + CO ₂

1.2Fe ₃ O ₄ + CO → 3.8Fe _0.95 O + CO ₂

Fe _0.95 + CO → _0.95 Fe + CO ₂

As can be seen from the scheme, when the sludge is heated at a high temperature, the iron component and carbon may react to recover the iron component (Fe).

Table 2 below shows an experimental example of recovering the iron component from the blast furnace sludge and blast furnace dust sludge. The experimental conditions are as follows.

Water is added to each of the blast furnace sludge and blast furnace dust sludge so that the moisture content is maintained at 15%. 9 wt% of cement is added to the blast furnace sludge and blast furnace dust sludge to form a molded body having a diameter of 50 cm and a height of 3 cm. The molded body is put together with electrolytic iron in an electric furnace, heated for 8 hours, and weighed.

Sample amount
(g) T-Fe
(wt%) M-Fe
(wt%) Theoretical recovery
(g) Melt increase
(g) Recovery
(%) blast furnace
Sludge 29.8 29.06 1.26 9.04 7.7 85.18 Blast furnace dust
Sludge 30.4 23.97 Tr 7.28 7.1 97.53

In Table 2, the theoretical recovery amount means the recovery amount when the iron component contained in the sludge is 100% recovered.

If blast furnace sludge contains 29.1 wt% of iron (T-Fe) and 20.2 wt% of carbon (C), the content ratio of carbon (C) to iron component (T-Fe) in blast furnace sludge is 0.69 (20.2 / 29.1). The recovery of iron component (M-Fe) was found to be 85.2% when the sludge content ratio was 0.69.

In addition, in the case of blast furnace dust sludge containing 24.0 wt% of iron (T-Fe) and 41.4 wt% of carbon (C), the content ratio of carbon (C) to iron component (T-Fe) in blast furnace dust sludge is 1.73 (41.4 / 24.0). When the blast furnace dust sludge content ratio was 1.73, the recovery of iron (M-Fe) was 97.53%.

The equation for the recovery rate of iron derived from the experimental results is as follows.

X = C content / T-Fe content

Y = 12.8X + 76.8

Here, X is the content ratio of carbon (C) to iron component (T-Fe), Y is the recovery rate of the iron component. According to this formula, when the content ratio of iron component (T-Fe) and carbon (C) is 1.1 to 2.0, the recovery rate of iron component (M-Fe) may be 90% or more.

It can be seen from the above experimental results that the recovery rate of the iron component depends on the content ratio of the iron component and the carbon. Therefore, by properly mixing the sludge generated in the various processes, it is possible to properly adjust the content ratio of the iron component and carbon of the sludge. By adjusting the content ratio it is possible to increase the recovery of the iron component.

A first embodiment of a method for manufacturing a scrap for an electric furnace using sludge according to the present invention will be described.

Referring to [Table 1], blast furnace dust dust sludge and hot rolled sludge have a high iron content (T-Fe) of more than 60%, but the content of carbon (C) is significantly low, such as 5%. In the drainage terminal sludge, the iron content (T-Fe) is very low as low as 5% but the carbon content as high as 24%. Therefore, by mixing a plurality of types of sludge it is possible to adjust the content ratio of the iron component and carbon. In addition, the carbon component may be added to the mixed sludge to increase the content of carbon.

First, the case where blast furnace sludge and blast furnace dust sludge are mixed will be described.

2 is a flow chart showing a method of manufacturing a scrap for an electric furnace using sludge according to an embodiment of the present invention.

2, blast furnace sludge and blast furnace dust sludge are mixed (S11). The blast furnace sludge contains 29.1 wt% iron and 20.2 wt% carbon. The blast furnace dust sludge contains 24.0 wt% iron and 41.4 wt% carbon.

When blast furnace sludge and blast furnace dust sludge are mixed in the same ratio, the mixed sludge has a carbon content ratio of about 1.16 to the iron component. That is, when calculating the content ratio by the formula, (20.2 + 41.4) / (29.1 + 24.0) = 1.16.

Since the mixed sludge may have a content ratio of about 1.16 and have an iron recovery rate of 90% or more, the coke which is a carbon component may not be added to control the content ratio. Of course, coke may be added to increase the recovery of the iron component.

The mixed sludge is broken into fine sludge powder (S12). The sludge powder can only be selected by the screen having a certain particle size.

Water is added to the sludge powder so that the water content of the sludge powder is 15 to 20% (S13). If the water content is less than 15% or more than 20%, it becomes difficult to produce a scrap molded body.

Cement is added to these sludge powders and mixed to produce a scrap molded body (S14). Cement may be added 6 ~ 9wt% relative to the sludge powder. The scrap molded body may be manufactured in an appropriate size in consideration of scrap input to the electric furnace.

The scrap for an electric furnace is manufactured by heating, drying, and baking a scrap molded object (S15).

Since the scrap for the electric furnace has a content ratio of 1.16 carbon to iron, the recovery of iron may be approximately 91%. Therefore, about 91% of iron components contained in the blast furnace sludge and the blast furnace dust sludge can be recovered.

Next, a description will be given of the production of scrap for an electric furnace by mixing blast furnace main dust sludge, drainage end sludge and hot rolled sludge.

3 is a flow chart showing a method of manufacturing a scrap for an electric furnace using sludge according to another embodiment of the present invention.

Referring to Figure 3, blast furnace columnar dust sludge, drainage terminal sludge and hot rolled sludge are mixed (S21).

At this time. Blast furnace dust sludge contains 61.8 wt% iron and 4.9% carbon. The drainage terminal sludge contains 4.9 wt% of iron and 23.5 wt% of carbon. Hot rolled sludge contains 61.3 wt% iron and 4.9 wt% carbon.

In the case where blast furnace dust dust sludge, drainage terminal sludge and hot rolled sludge are mixed in the same ratio, the mixed sludge has a carbon content ratio of about 0.26 to the iron component. That is, when calculating the content ratio by the formula, (4.9 + 23.5 + 4.9) / (61.8 + 4.9 + 61.3) = 0.26.

Such mixed sludge may have a content ratio of about 0.26, thereby lowering the iron recovery. In order to increase the carbon content of the mixed sludge, coke, which is a carbon component, may be added (S22). At this time, the coke may be added so that the content ratio of carbon to iron component is about 1.1 ~ 2.0. This is to recover more than 90% of the iron component in the mixed sludge.

The mixed sludge is crushed into fine sludge powder (S23). The sludge powder can only be selected by the screen having a certain particle size.

Water is added to the sludge powder so that the water content of the sludge powder is 15 to 20% (S24). When the water content is about 15 to 20%, the shape of the scrap molded body can be maintained normally.

Cement is added to these sludge powders and mixed to produce a scrap molded body (S25). Cement may be added 6 ~ 9wt% relative to the sludge powder. The scrap molded body may be manufactured in an appropriate size in consideration of scrap input to the electric furnace.

The scrap for an electric furnace is manufactured by heating, drying, and baking a scrap molded object (S26).

In the electric furnace scrap, the content ratio of the carbon component to the iron component is controlled by coke, so that the recovery rate of the iron component can be increased.

In the above, two mixing examples of the sludge have been described. Since the carbon component can be controlled by the coke, the mixing example of the sludge can be varied. For example, blast furnace slag, blast furnace dust slag, blast furnace columnar dust slag, drainage end slag, hot rolled slag, etc. can all be mixed or only some. And, by adding coke to adjust the content ratio of the iron component and the carbon component can increase the recovery rate of the iron component.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

10: steelmaking process 20: steelmaking process
30: rolling process 40: drainage end treatment

Claims (7)

Mixing different types of sludge to adjust the content ratio of iron and carbon components;
Crushing the mixed sludge to produce sludge powder;
Adding water to the sludge powder so that the water content of the sludge powder is 15 to 20%;
Manufacturing a scrap molded body by adding cement to the sludge powder; And
Drying and firing the scrap molded body,
In the method for producing a scrap molded body, 6 to 9% of the cement compared to the sludge powder, the method for producing a scrap for an electric furnace using sludge.
The method of claim 1,
After the mixing of the other sludge, the method for producing a scrap for an electric furnace using the sludge further comprising the step of adjusting the content of the carbon component by adding coke to the mixed sludge.
3. The method of claim 2,
The coke is a method for producing a scrap for an electric furnace using a sludge, characterized in that the content ratio of the carbon component to the iron component is adjusted to 1.1 ~ 2.0.
delete The method according to any one of claims 1 to 3,
In the step of producing the sludge powder blast furnace sludge and blast furnace dust sludge is a method for producing a scrap for an electric furnace using sludge, characterized in that the mixture.
The method according to any one of claims 1 to 3,
In the step of producing the sludge powder, blast furnace columnar dust sludge, drainage terminal sludge and hot rolled sludge are mixed, characterized in that the manufacturing method of the scrap for the furnace using sludge.
The method according to claim 6,
The blast furnace columnar dust sludge, hot rolled sludge and drainage terminal sludge is a method for producing a scrap for an electric furnace using the sludge, characterized in that the mixing in the same ratio.

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