JP3187461B2 - Slag smelting reduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively utilizing steelmaking slag generated in the process of refining steel.

[0002]

2. Description of the Related Art Steel smelting furnaces generate a large amount of slag, and some of them are reused, but most of them are buried or disposed of. In particular, oxidized refining slag in an electric furnace has a drawback that its use is extremely restricted due to the slag's expandability. Therefore, Japanese Patent Publication No. 555-2
As described in Japanese Patent No. 7140, a method has been proposed in which slag generated from an electric furnace is placed in a slag storage container and treated while maintaining a temperature at which the fluidity is not impaired by a heat retaining electrode.

[0003]

However, treating slag by the above method requires a large amount of power, increases the cost, and requires special equipment such as electrodes. The present invention has been made in view of such circumstances, and has as its object to provide a slag smelting reduction treatment method that can treat slag by a relatively inexpensive method and can effectively use the slag.

[0004]

According to a first aspect of the present invention, there is provided a slag smelting reduction method according to the first aspect, comprising: placing oxidized slag generated during steel refining and reduced slag in a slag melting furnace; In the slag melting furnace, metallic iron powder is added to dissolve the acid by blowing, and the slag basicity is adjusted to 1.9 or less.
The steel is collected as blast furnace slag and the iron contained is recovered as pig iron. Here, it is preferable to use converter refined iron powder (OGP) as the metal iron powder from the viewpoint of easy handling and inexpensive in view of the shape.

[0005]

In the slag smelting reduction treatment method according to the present invention, an appropriate amount of oxidized slag and reduced slag are placed in a slag melting furnace so that the basicity is 1.9 or less.
Since metal acid powder is added to dissolve acid,
Iron powder can be used as a heat source. Since the oxidized slag and the reduced slag are blended and the blowing acid is dissolved, the reaction heat generated by the oxide in the oxidized slag and the non-oxide in the reduced slag can be positively used. In addition, since the acidity of dissolving the slag is increased by setting the basicity of the slag to 1.9 or less, the fluidity of the slag increases, and almost complete slag reforming becomes possible.
Furthermore, the slag produced and discharged by the reduction smelting furnace by utilizing the slag for the reduction smelting furnace can have high added value. If the basicity of the slag mixed here is higher than 1.9, the slag metal reaction in the blast furnace will be hindered. Further, by this treatment, the iron, iron oxide and other valuable metals contained in each slag are reduced and recovered from the molten slag into the molten iron during the reaction treatment in the blast furnace.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows schematic steps of a slag smelting reduction treatment method according to one embodiment of the present invention. First, an oxidized slag 11 and a reduced slag 12 are taken out from an electric furnace 10 which is an example of a refining furnace. Place in melting furnace 13. In this case, the amounts of the oxidized slag 11 and the reduced slag 12 are adjusted so that the basicity (referred to as the Ca / SiO ₂ ratio) is in the range of 1.9 or less. That is, the components of the oxidized slag and the reduced slag of the electric furnace are generally as shown in Table 1, and their basicities are 1.4 in the case of oxidized slag and 2.1 in the case of reduced slag.
Becomes

[0007]

[Table 1]

Therefore, in order to make the basicity 1.9 or less, the amount of reduced slag is set to x with respect to the amount of oxidized slag of 1 so as to satisfy the following expression.

[0009]

(Equation 1)

When this equation is solved, x ≦ 1.99. Therefore, the basicity is adjusted by adding 1.99 times or less (preferably 1 or more) reduced slag to 1 oxidized slag. Will be

Accordingly, after the predetermined amounts of the oxidized slag 11 and the reduced slag 12 are put into the slag melting furnace 13, as shown in FIG. While blowing oxygen,
The converter-produced iron powder is burned. The amount of the blown iron powder generated by the converter depends on the amount of the supplied reducing slag and the oxidized slag, but is considered to have sufficient fluidity, and furthermore, is in the range of 8 to 15% of the amount of the supplied slag. It is preferable to do so.

Next, in this state, the blast furnace is cooled and processed into lumps or granules, and is used as a raw material for a blast furnace 14 which is an example of a reduction furnace. As a result, iron oxide in the slag becomes reduced pig iron, and the slag becomes blast furnace slag, which can be appropriately crushed to produce blast furnace ballast or sand, which can be used as a building material. In this embodiment, a blast furnace was used as a reduction furnace. However, a process for producing pig iron by directly using recently developed coal and iron ore without prior treatment such as coking and agglomeration (usually a DIOS method) It is also possible to carry out the treatment in an iron bath smelting reduction furnace.

[0013]

According to the first aspect of the present invention, the slag smelting reduction method is used as a raw material for a blast furnace by appropriately blending oxidized slag and reduced slag generated in a smelting furnace as described above. The ability to do so has expanded its use. Further, when heating the above-mentioned oxidized slag and reduced slag, metal iron powder is used, so that the production cost can be reduced, and the iron oxide in which the metal iron powder and oxygen are combined is melted in the next reduction furnace. Since it is reduced, iron can be recovered.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram of a slag smelting reduction treatment method according to an embodiment of the present invention.

[Explanation of symbols]

10: Electric furnace (refining furnace), 11: Oxidized slag, 12: Reduction slag, 13: Slag melting furnace, 14: Reduction furnace

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21C 5 / 28,7 / 00 C22B 7/04 F27D 15/00 C21B 3 / 04,3 / 06

Claims (1)

(57) [Claims] Claims 1. After oxidized slag and reduced slag generated during the refining of steel are put into a slag melting furnace, metallic iron powder is added to the slag melting furnace to perform blowing acid dissolution, and the slag basicity is increased. Slag is adjusted to 1.9 or less, the slag produced thereby is put into a blast furnace and collected as blast furnace slag, and the contained iron is collected as pig iron.