KR20080088338A - Composition for scrap alternative material produced by mill-scale, briquet and metal reduction method - Google Patents

Abstract

A composition for a scrap alternative material produced by mill-scale, a briquette produced by the same, and a metal reduction method using the briquette are provided to manufacture the briquette using the composition by mixing the mill-scale, a reducing agent, and an inorganic binder or an organic binder, and melting the briquette in an electric furnace for preventing temperature drop and reducing operation lead time. A composition for a scrap alternative material is produced by mixing 70 to 95 weight% of the dried and sorted mill-scale, 3 to 25 weight% of a reducing agent, 0.5 to 10 weight% of an inorganic binder, and 0.5 to 10 weight% of an organic binder. The reducing agent is made by mixing one or at least two of cokes dust, precipitation cokes, pulverized coal and anthracite, soft coal, graphite, and bituminous coal. The inorganic binder is made by mixing one or at least two of fluorite powder, sodium silicate, bentonite, zeolite, colloidal silica, aluminium phosphate, asphalt emulsion, slaked lime, waste plastic, and cement.

Description

Composition for scrap substitute using mill scale, iron reduction method using briquette and briquette manufactured using the same {COMPOSITION FOR SCRAP ALTERNATIVE MATERIAL PRODUCED BY MILL-SCALE, BRIQUET AND METAL REDUCTION METHOD}

The present invention relates to a recycling method of mill scale (iron oxide) generated in the steelmaking process and rolling process, in particular, by adding a reducing agent and an inorganic binder or an organic binder to prepare a composition for scrap substitutes and using it as a briquette The present invention relates to a method of manufacturing and reducing the briquettes in an electric furnace, a converter and a furnace so that they can be used as a scrap substitute.

In general, mill scale generated in the steelmaking and rolling processes contains a large amount of iron, which is a useful component. However, due to the low number of particles and the high amount of iron oxide, it is simply recycled at low temperatures in electric furnaces and steel mills.

Recently, the steel industry and the Ministry of Environment have sharply confronted the problem of recycling mill scales generated in the steelmaking process and rolling process as described above, and such mill scales are used in the US, Japan, Taiwan, etc. Although it is handled as scrap metal, it is being processed as a low-grade recycled material in Korea, and about 25% of the mill scale generated during the steelmaking process is supplied for recycling to steel mills such as POSCO, and the remaining 75% to China, Japan, etc. Some are known to be exported.

An example of the technology for manufacturing and recycling a scrap substitute is Republic of Korea Publication No. 2001-17294. The method for producing a scrap substitute disclosed herein uses a hot rolled oil sludge containing oil as a main material, mixes coke dust, bentonite, and portland cement, adds moisture, forms a mold, and then dry it to be used as a scrap substitute. Techniques are disclosed.

However, the technique disclosed in the above publication is a method using hot rolled oil sludge, which has a disadvantage in that the manufacturing cost is increased by combining a complex and relatively expensive mixture with a hot rolled sludge collection process.

The present invention has been invented to solve the above problems, in order to easily recycle the mill scale generated in a large amount in the steelmaking and rolling process, the mill scale as a main component and a reducing agent, an organic binder and an inorganic binder It provides a method of preparing a composition made by mixing and forming the composition into a block-like briquette, and then melting the briquette prepared above in an electric furnace, a converter and a furnace to prevent reduction and temperature drop at high efficiency. It is technical problem to do.

In order to achieve the object of the present invention as described above,

The present invention firstly, the composition for the scrap substitute composition consisting of mixing 70 to 95% by weight, selected mill scale, 3 to 25% by weight of reducing agent, 0.5 to 10% by weight of inorganic binder, 0.5 to 10% by weight of organic binder Provided as a solution (first invention).

In another aspect, the present invention provides a composition for scrap replacement material consisting of at least one selected from coke dust, precipitated coke, pulverized coal and anthracite coal, bituminous coal, graphite, bituminous coal as the reducing agent in the first invention. .

In the first aspect of the present invention, the inorganic binder is substituted with at least one selected from fluorite powder, sodium silicate, bentonite, zeolite, colloidal silica, aluminum phosphate, asphalt emulsion, slaked lime, waste plastic, and cement. The preparation composition is provided as a problem solving means.

In another aspect, the present invention provides a composition for the substitution of scrap consisting of at least one selected from molasses, potato starch, corn starch, palm wax as the organic binder as a means for solving the problem.

Secondly, the present invention provides a briquette made of a scrap substitute composition composed of a mill scale, a reducing agent, an inorganic binder, and an organic binder (second invention).

Thirdly, the present invention specifically defines the second invention, which is 70 to 95% by weight of dried and selected mill scale, 3 to 25% by weight of reducing agent, 0.5 to 10% by weight of inorganic binder, and 0.5 to 10 of organic binder. A briquette made of a composition for scrap substitution made by mixing the weight% is provided as a problem solving means (third invention).

Finally, the present invention is blended, dried, selected mill scale 70 to 95% by weight, reducing agent 3 to 25% by weight, inorganic binder 0.5 to 10% by weight, organic binder 0.5 to 10% by weight of the molding, curing and drying step Manufacturing briquettes through; It provides a method for reducing iron using a briquette for scrap substitutes comprising the step of dissolving and reducing the briquette prepared in a high frequency electric furnace (fourth invention).

In the present invention to provide a means for solving the above problems, the mill scale used as the main component is generated as a by-product in the rolling process and steelmaking process, the composition of the main components are T-Fe, CaO SiO ₂ , Al ₂ O ₃ , MgO, K ₂ O, Mn, Zn, Cu, S, TiD ₂ , CaF ₂ , oil and the like are mixed.

As the reducing agent, a carbonaceous material composed mainly of carbon is used, and as such a carbonaceous material, coke dust, pulverized coal, precipitated coke, anthracite coal, bituminous coal, graphite, and the like can be used. Any one of the components may be optionally used, and at least two or more kinds may be arbitrarily mixed. Here, the carbon component of the coal ash used as a reducing agent is a component added to reduce the iron oxide in the mill scale during the manufacture of the scrap substitute, and is also a component that can be used as a heat source preservative in a furnace.

The content of the reducing agent to be added is preferably added 3 to 25% by weight. If 3% by weight or less is added, the reduction rate is drastically lowered, the efficiency as a heat preservative is also lowered, and when 25% by weight or more is added, the by-products become excessive and it is impossible to use it as a scrap substitute, resulting in deterioration of productability. Not preferred.

The inorganic binder may be used by mixing at least one selected from fluorite powder, sodium silicate, bentonite, zeolite, colloidal silica, aluminum phosphate, asphalt emulsion, slaked lime, waste plastic, and cement.

In addition, the organic binder may be optionally mixed with one or two or more components selected from molasses, potato starch, corn starch, palm wax.

In addition, in order to form a briquette using the composition of the present invention, the inorganic binder is mixed in an amount of 0,5 to 10% by weight or 0.5 to 10% by weight of an organic binder. If the amount of the binder is less than 0.5% by weight, the bonding strength is lowered, briquette molding is difficult, and if it contains more than 10% by weight, there is a problem that the cost is too high and commercialization is difficult.

As described above, an organic binder or an inorganic binder is added to the mixture of the mill scale and the reducing agent, and the composition is mixed, cured, and dried using briquettes. Briquettes obtained after performing a series of processes are to be used as a scrap substitute by reducing in a high-temperature electric furnace, converter, furnace.

In the present invention, the briquette is manufactured with a composition consisting mainly of mill scale, and the briquette is reduced in an electric furnace, a converter and a furnace to be used as a scrap substitute, but the oxygen-cut iron may also be used as a main component as a substitute for mill scale. Make sure you can.

As shown in FIG. 1, the present invention undergoes a drying process to remove appropriate moisture from the collected mill scale. Thereafter, 70 to 95% by weight of the dried mill scale and 3 to 25% by weight of the reducing agent were mixed by crushing and sorting, and 0.5 to 10% by weight of the inorganic binder and 0.5 to 10% by weight of the organic binder were added and mixed. It is prepared as a composition and is subjected to a process of forming, curing and drying in a uniform form (for example, block type) using such a composition to produce a briquette of a constant size.

The present invention can easily recycle the mill scale generated in a large amount in the steelmaking process and rolling process, and provides a composition comprising a mill scale as a main component and mixed with a reducing agent and an organic binder or an inorganic binder, using such a composition After the production of briquettes, it is used in the electric furnace to melt the manufactured briquettes and reduce them with high efficiency, and in the converter to prevent the temperature decrease by the role of a reducing agent to help improve productivity by reducing the lead time of the operation, iron ore in the furnace It can be used as a substitute and is a useful invention in terms of resource recycling.

Hereinafter, an embodiment in which a composition formed by mixing a mill scale, a reducing agent, an organic binder, and an inorganic binder and a reduction rate produced by reducing briquettes using the same will be described in detail.

Example 1

The composition was prepared by adding and mixing 83 weight% of mill scales previously selected and selected, 7 weight% of coke dust, 9 weight% of an inorganic binder, and 1 weight% of an organic binder as a reducing agent. This composition was made into a briquette and cured and dried.

Subsequently, the prepared briquettes were manufactured with molten iron in a high frequency induction melting furnace. The temperature of the high-frequency induction furnace was 90 minutes after the briquette at 0 ℃ was measured for the iron reduction rate. In the measuring method, the amount of iron (Fe) contained in the mill scale contained in the briquette and the amount of iron (Fe) contained in the iron dissolved in the furnace (hereinafter referred to as molten iron) were respectively measured before the briquette was added. . The iron reduction rate was 76.1%. The iron reduction rate was calculated by the following equation (1).

Iron reduction rate (%) = amount of iron in molten iron / amount of iron in mill scale × 100 --------- (Equation 1)

Example 2

The composition was prepared by adding and mixing 81 weight% of mill scales previously selected and selected, 9 weight% of coke dust, 9 weight% of inorganic binders, and 1 weight% of organic binders as a reducing agent. It was prepared using this composition and cured and dried.

Subsequently, the briquettes were manufactured with molten iron in a high frequency induction furnace. The temperature of the high-frequency induction furnace was measured for iron reduction after 90 minutes after the briquette at 0 ℃. In the measuring method, the amount of iron (Fe) contained in the mill scale contained in the briquette and the amount of iron (Fe) contained in the iron dissolved in the furnace (hereinafter referred to as molten iron) were respectively measured before the briquette was added. . The iron reduction rate was 78.1%. Iron reduction rate was calculated by the following formula (1).

Iron reduction rate (%) = amount of iron in molten iron / amount of iron in mill scale × 100 --------- (Equation 1)

Example 3

76% by weight of the dried and selected mill scale, 14% by weight of coke dust, 9% by weight of inorganic binder, and 1% by weight of organic binder were added and mixed to prepare a composition, and a briquette was prepared, cured and dried using the same. .

Subsequently, the briquettes were manufactured with molten iron in a high frequency induction furnace. The temperature of the high-frequency induction furnace was measured for iron reduction after 90 minutes after the introduction of the briquette at 0 ℃. In the measuring method, the amount of iron (Fe) contained in the mill scale contained in the briquette and the amount of iron (Fe) contained in the iron dissolved in the furnace (hereinafter referred to as molten iron) were respectively measured before the briquette was added. . The iron reduction rate was 93.8%. Iron reduction rate was calculated by the following formula (1).

Iron reduction rate (%) = amount of iron in molten iron / amount of iron in mill scale × 100 --------- (Equation 1)

Example 4

73 wt% of pre-dried and selected mill scale, 17 wt% of coke dust, 9 wt% of inorganic binder, and 1 wt% of organic binder were added and mixed to prepare a composition, and a briquette was prepared, cured and dried using the same. .

Subsequently, the briquettes were manufactured with molten iron in a high frequency induction furnace. The temperature of the high-frequency induction furnace was 90 minutes after the briquette at 0 ℃ was measured for the iron reduction rate. The measuring method measured the amount of iron (Fe) contained in the mill scale contained in the briquettes and the amount of iron (Fe) contained in the iron dissolved in the furnace (hereinafter referred to as molten iron) before the briquette was added. . The iron reduction rate was 96.3%. The iron reduction rate was calculated by the following equation (1).

Iron reduction rate (%) = amount of iron in molten iron / amount of iron in mill scale × 100 --------- (Equation 1)

Comparative example

65 wt% of the dried mill scale, 28 wt% of coke dust, 6 wt% of inorganic binder, and 1 wt% of organic binder were added and mixed to prepare a composition, and a briquette was used to cure and dry.

Subsequently, the briquettes were dissolved and reduced in a high frequency induction furnace to prepare an electric furnace steel scrap substitute. The temperature of the high-frequency induction furnace was measured for iron reduction after 90 minutes after the briquette at 0 ℃. In the measuring method, the amount of iron (Fe) contained in the mill scale contained in the briquette and the amount of iron (Fe) contained in the iron dissolved in the furnace (hereinafter referred to as molten iron) were respectively measured before the briquette was added. . The iron reduction rate was 40%. Iron reduction rate was calculated by the following formula (1).

Iron reduction rate (%) = amount of iron in molten iron / amount of iron in mill scale × 100 --------- (Equation 1)

The amount of components contained in Examples 1 to 4 and Comparative Example 1 was shown in Table 1.

ingredient Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Mill scale 65% by weight 83% by weight 81% by weight 76% by weight 73% by weight Reducing Agent (Coke Dust) 28 wt% 7 wt% 9% by weight 14 wt% 17% by weight Weapon Binder 6% by weight 9% by weight 9% by weight 9% by weight 9% by weight Organic Binder 1 wt% 1 wt% 1 wt% 1 wt% 1 wt%

In addition, the results for the iron reduction rate according to Examples 1 to 4 and Comparative Example 1 are shown in Table 2 below. It can be seen that the iron reduction rate of Examples 1 to 4 is relatively good in the range of 76.1 to 96.3%, and the iron reduction rate is remarkably decreased when the amount of mill scale is added to about 65% by weight. And it can be seen from the results of the implementation that the most preferred examples are Examples 3 and 4.

Therefore, it can be seen that the best iron reduction rate is contained in the range of 70 to 95% by weight of the mill scale, 3 to 25% by weight of reducing agent, 0.5 to 10% by weight of inorganic binder, and 0.5 to 10% by weight of organic binder. have.

The content of the reducing agent added in the present invention is preferably added 3 to 25% by weight. When 3% by weight or less of the reducing agent is added, the reduction rate is drastically lowered, the efficiency as a heat preservative is also lowered, and when 25% by weight or more is added, the by-products are excessive and it is impossible to use it as a scrap substitute. This lowers and is not preferable.

In addition, in order to form a briquette with the composition of the present invention, it is preferable to mix 0,5 to 10% by weight of the inorganic binder or 0.5 to 10% by weight of the organic binder in the mill scale composition. If the amount of the binder is less than 0.5% by weight, there is a difficulty in forming briquettes due to a decrease in bonding strength, and when the content is more than 10% by weight, excessive cost is required.

result Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Iron reduction rate (%) 40 76.1 78.1 93.8 96.3

In order to compare the time to reach the iron reduction rate, which is usually required in the steelmaking process, the time required for the iron reduction rate was measured while increasing the temperature to 1,500 ° C. after the temperature of the high frequency melting furnace was added at 0 ° C. Table 3 shows this result. As a result of the measurement, Example 1 took 80 minutes, Example 2 took 79 minutes, Example 3 took 72 minutes, and Example 4 took 66 minutes, which shows that the metallization time was significantly shortened compared to 85 minutes of Comparative Example 1. .

result Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Required time (minutes) 85 minutes 80 minutes 79 minutes 72 minutes 66 minutes

As described above, the present invention can easily recycle the mill scale generated in a large amount in the steelmaking process and rolling mills, to prepare a composition consisting of mill scale as a main component and mixed and blue and mixed with organic and inorganic binders, and such a composition After molding into a bracket using it can be used to melt the bracket prepared above in an electric furnace or the like and to reduce the efficiency and prevent temperature drop with high efficiency.

1 is a block diagram schematically illustrating a manufacturing process of the present invention.

Figure 2 is a comparative graph showing the iron reduction rate (%) according to the compounding ratio of Table 1.

Figure 3 is a comparative graph showing the time required to reach the appropriate iron reduction rate according to the mixing ratio of Table 1.

Claims (7)

70 to 95% by weight of the dried, selected mill scale, 3 to 25% by weight of the reducing agent, 0.5 to 10% by weight of the inorganic binder, 0.5 to 10% by weight of the organic binder composition for the scrap substitute. The method according to claim 1, The reducing agent is a composition for scrap substitutes consisting of any one or at least two or more selected from coke dust, precipitated coke, pulverized coal and anthracite coal, bituminous coal, graphite, bituminous coal. The method according to claim 1, The inorganic binder is a composition for scrap substitution, optionally consisting of one or at least two or more selected from fluorite powder, sodium silicate, bentonite, zeolite, colloidal silica, aluminum phosphate, asphalt emulsion, slaked lime, waste plastic, cement. The method according to claim 1, The organic binder is a composition for scrap substitutes formed by arbitrarily mixing one or at least two selected from molasses, potato starch, corn starch, palm wax. Briquette made of a scrap substitute composition consisting of a mill scale, a reducing agent, an inorganic binder, an organic binder. A briquette made of a composition for scrap replacement, comprising 70 to 95% by weight of a dried, selected millscale, 3 to 25% by weight of a reducing agent, 0.5 to 10% by weight of an inorganic binder, and 0.5 to 10% by weight of an organic binder. 70 to 95% by weight of the dried, screened mill scale, 3 to 25% by weight of reducing agent, 0.5 to 10% by weight of inorganic binder, 0.5 to 10% by weight of organic binder, followed by molding, curing and drying to produce briquettes step; Iron reduction method using a briquette for scrap substitutes comprising the step of melting and reducing the briquette prepared in the high-frequency electric furnace.

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