KR20050063920A - Method for manufacturing ferro-chrome alloy iron from byproduct of stainless steel - Google Patents

Abstract

The present invention relates to a method for producing a ferro-chromium alloy with uniform components by producing by-products produced in the steelmaking process into a molded body and melt-reducing the molded body using an electric furnace.

The present invention is to prepare pellets by using these by-products and to melt the pellets in order to reduce and recover valuable metals from iron by-products of the stainless steel manufacturing process, refinery heavy dust, refinery dust and scale iron-containing by-products In the method of producing ferro-chromium alloy by reducing,

Coke dust: 5 to 20 parts by weight, binder: 8 to 20 parts by weight based on 100 parts by weight of the iron-containing by-products, characterized in that for producing a pellet.

The present invention improves the compressive strength of the pellets by mixing the coke dust when the pellets are manufactured by using the by-products of the stainless steel production process to improve the compressive strength of the pellets when flying the raw material to the belt conveyor, etc. In addition to reducing dust and reducing dust generated during melt reduction, there is an effect of obtaining component homogenization of ferroalloy.

Description

Method for manufacturing ferro-chrome alloy iron from by-products of stainless steel}

The present invention relates to a method for producing a by-product generated in the steelmaking process into a molded body and to produce a ferro-chromium alloy with uniform components by melt reduction of the molded body using an electric furnace, more specifically in the stainless steel manufacturing process When the pellets are manufactured by using the generated by-products as the main raw materials, there is no decrease in the strength of the pellets, thus reducing the generation of scattering dust when mixing various raw materials for melting in the electric furnace, and reducing the amount of dust generated during the melt reduction operation, as well as alloys. The present invention relates to a method for producing ferro-chromium alloy iron using iron and steel by-products capable of obtaining a homogeneous component of iron.

Stainless steel is produced by melting molten iron and ferroalloy in an arc furnace using arc heat to make molten steel, and refining the molten steel in a refining furnace. In such a stainless steel manufacturing process, various by-products are generated for each process. In the electric furnace, electric dust is generated, in the refinery, heavy dust is generated in the refining furnace of coarse particles, and in the dust collector, dust is collected by fine refining.

In addition to iron components, such electric furnace dust and refining furnace dust contain a large amount of valuable metals such as Cr and Ni. Therefore, the by-products are manufactured in a molded body and dissolved in a small electric furnace to recover ferroalloy, and the generated slag is recycled as a raw material for construction.

The prior art for producing by-products produced in the stainless steel manufacturing process in the form of a molded article is Korean Patent Laid-Open Publication No. 2000-13357 (aging device of quicklime-containing dust for producing briquettes). The prior art relates to a aging device for recycling by-products generated in the stainless manufacturing process. In the aging apparatus, water is added without any distinction between electric dust and refining dust, followed by hydration treatment as in Scheme 1 below.

Scheme 1

CaO + H ₂ O → Ca (OH) ₂ + 15.2 kcal / mol

The raw material aged as described above is prepared by briquetting by mixing a binder such as molasses.

However, it is difficult to control the amount of water in the process of forming the dust generated in the stainless manufacturing process to briquettes, so that the hydration reaction of the unhydrated quicklime proceeds after molding, which causes the briquettes to be differentiated and disintegrated.

The present invention is to solve the above-mentioned problems of the prior art, the production of pellets for recycling by-products such as dust and scale generated during the manufacturing process of stainless steel to increase the strength without causing a decrease in strength of the pellets of the molded body SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing ferro-chromium ferroalloy using steel by-products which can homogenize components of ferro-chromium ferroalloy and improve valuable metal recovery efficiency by reducing the differentiation rate.

The present invention for achieving the above object,

In order to reduce and recover valuable metals from electric furnace dust, refinery heavy dust, refinery dust and scale iron-containing by-products generated in the stainless steel manufacturing process, pellets are prepared using these by-products, and the pellets are melted and reduced to ferro In the method for producing chromium alloy iron,

Coke dust: 5 to 20 parts by weight, binder: 8 to 20 parts by weight based on 100 parts by weight of the iron-containing by-products, characterized in that for producing a pellet.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In general, in order to recover valuable metals such as iron, chromium or nickel in the by-products, powder by-products such as dust or sludge may be manufactured into a molded body through a molding process, or the powder itself may be directly recycled.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recovering a present component having a low component deviation through a melting reduction furnace such as S.E.F (Submerged Electric Furnace) after producing a pellet-shaped molded product using powdered steel by-products.

In this case, as the available steel by-products, especially in the case of dust collected in the cyclone of the electric furnace and refining furnace in the production of stainless steel, the particles are thicker than the dust collected in the dust collector. Therefore, when the pellets are manufactured using these dusts, the particles are thick and the density of the pellets is low, thereby reducing the strength of the pellets. Therefore, for the densification of pellets, the densification is enhanced by mixing scales with small particles.

In the present invention, when the pellets are manufactured using the coarse dust as a main raw material as described above, the fine coke dust is mixed to prepare the pellets, thereby increasing the green strength at room temperature. Due to the carbon component, it is possible to obtain an effect of improving the high temperature hot strength of the pellet by homogeneous reduction and promotion of liquid phase sintering. Therefore, according to the present invention, it is possible to reduce the differentiation and decay phenomenon when handling the pellets at room temperature and high temperature, it is possible to reduce the amount of dust generated during melt reduction is preferable to the operating environment. In addition, the added coke dust has good thermal conductivity inside the pellets, which causes the pellets to melt homogeneously and helps to reduce the component deviation of the ferroalloy.

Hereinafter, the ferro-chromium ferroalloy manufacturing method of the present invention will be described.

First, pellets are prepared by adding coke dust: 5 to 20 parts by weight and a binder: 8 to 20 parts by weight to 100 parts by weight of the iron-containing by-product including electric furnace dust, refining furnace heavy dust, refining furnace dust and scale.

In the present invention, the mixing ratio of the electric iron dust, the refinery heavy dust, the refinery dust and the scale are not limited.

If the amount of coke dust added to the iron by-products is less than 5 parts by weight based on 100 parts by weight of iron by-products, the improvement in room temperature strength and hot strength is insufficient. Because of this decreasing problem, the amount of coke dust added is preferably limited to 5 to 20 parts by weight based on 100 parts by weight of iron-containing byproducts.

At this time, when the particle size of the coke dust is 0.15mm or less, the coke dust is filled between the coarse particles in the iron-containing by-product including electric furnace dust, refining furnace heavy dust, refining dust and scale to further densify the density of the molded body. Since it shows an effect, it is more preferable.

In addition, when the amount of the binder added is less than 8 parts by weight based on 100 parts by weight of iron by-products, the strength is lowered. When the amount of the binder is added by more than 20 parts by weight, there is no increase in effect due to the addition. It is preferable to limit it to 20 parts by weight. The binder is not particularly limited, and in general, it is possible to use portland cement, an inorganic binder having hydraulic properties, for example, a fast cement, a landscaping cement, a blast furnace slag cement, a fly ash cement, and the like.

Thereafter, the pellets are melt-reduced to produce ferro-chromium ferroalloy. The melt-reduction process may be performed using a conventional method.

In the melt reduction process, a conventional melt reduction furnace, such as a blast furnace coke-filled shaft melting furnace or a submerged electric furnace (SEF) type electric furnace or a coke bed reduction furnace, which combines a blast furnace type and an electric furnace type, may be used. .

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

The chemical composition of the raw material used in the present Example was investigated, and the results are shown in Table 1 below. In addition, the cumulative particle size distribution of the raw material was investigated, and the results are shown in Table 2 below.

division CaO MgO SiO ₂ M-Fe T-Fe Al ₂ O ₃ ZnO NiO Cr ₂ O ₃ MnO Electric furnace 4.4 1.5 7.1 1.1 29.1 0.4 7.4 2.1 19.1 3.4 Refining furnace heavy dust 26.8 6.1 8.5 12.2 32.6 0.3 0.01 2.5 14.4 4.4 Refinery Dust 23.9 5.8 5.4 5.0 30.2 0.3 0.6 2.6 14.2 3.3 scale 4.0 0.3 2.5 11.0 49.5 tr tr 7.6 15.5 1.1 Coke dust 0.8 0.3 5.9 tr 0.5 2.9 tr tr tr tr Binder (usually Portland Cement) 61.3 2.1 19.0 tr 2.0 4.9 tr tr tr tr

division Electric furnace (%) Refining furnace heavy dust (%) Refinery Dust (%) scale(%) Coke dust (%) 0.710 mm pass 100 85 100 100 - 0.500mm pass 95 75 99 99 - 0.300mm pass 85 36 98 98 - 0.250mm pass 76 30 97 97 - 0.150mm pass 60 15 95 75 100 0.075 mm pass 31 3 62 16 81 0.045mm pass 2 One 25 3 62

Pellets were prepared using the above raw materials, and the mixing ratio of the raw materials of the dust and the scale is not particularly limited, but in the embodiment of the present invention, the sum of the refining furnace heavy dust is 35% by weight, the electric furnace dust, and the refining dust of the refining furnace. 20 wt% and scale were 45 wt%. Coke dust was added to the raw materials in the amounts shown in Table 3 below, and pellets were prepared after mixing 11 parts by weight of ordinary portland cement having a component of Table 1 as a binder with respect to 100 parts by weight of the raw material. Then, the change in room temperature strength and hot strength according to the addition of coke dust was measured, the results are shown in Table 3 below. The room temperature strength is the compressive strength measured after 15 days after the pellets are manufactured, and the hot strength is measured after the pellets 15 days after the pellets have been heat-treated at 1000 ° C. for 1 hour under argon gas atmosphere. It is.

In addition, the recovery rate and the current component deviation was measured now, the results are shown in Table 3 below. The now recovery rate is expressed as a fraction of the weight made of ferroalloy except the amount of slag and dust generated after melting with respect to the weight of the total pellet used in the melt reduction, the deviation of the present component is the initial and second parts of the manufactured ferroalloy The degree of deviation is measured by measuring the components.

division Sum of iron by-products (parts by weight) Coke dust (part by weight) Room temperature strength Hot strength Recovery rate now (%) Ingredient deviation Comparative Example 1 100 0 80 18 45 △ Inventive Example 1 100 5 97 56 46 ◎ Inventive Example 2 100 20 83 20 46 ◎ Comparative Example 2 100 30 31 3 43 × ◎: Good- △: Normal- ×: Poor

As can be seen in Table 3, Inventive Example 1 and Inventive Example 2 satisfying the scope of the present invention was superior to room temperature strength and hot strength, now recovery rate, now component variation compared to the comparative example.

However, in the case of Comparative Example 1 without the addition of coke dust, the room temperature strength and the hot strength were lower than those of the present invention, and the present component variation was not so good.

In addition, in the case of Comparative Example 2 in which more coke dust was added than the range of the present invention, the room temperature strength, the hot strength, the recovery rate, and the current component deviation were all very poor.

As described above, according to the present invention, when the pellets are manufactured by using the by-products of the stainless steel manufacturing process, coke dust is mixed to prepare the pellets, thereby improving the compressive strength of the pellets. It is possible to reduce the amount of scattering dust generated by falling and the like and reduce the amount of dust generated during melt reduction, as well as to obtain a homogeneous component of ferroalloy.

Claims (2)

In order to reduce and recover valuable metals from electric furnace dust, refinery heavy dust, refinery dust and scale iron-containing by-products generated in the stainless steel manufacturing process, pellets are prepared using these by-products, and the pellets are melted and reduced to ferro In the method for producing chromium alloy iron, Coke dust: 5 to 20 parts by weight, binder: 8 to 20 parts by weight based on 100 parts by weight of the iron by-product by using a method for producing ferro-chromium alloy iron using iron by-products, characterized in that for producing a pellet. The method of claim 1, wherein the coke dust has a particle size of 0.15 mm or less.