JPS61235505A - Electric refining method for modifying slag - Google Patents

Abstract

PURPOSE:To lower the alumina content in produced slag by using nonaluminous brick as the lining refractory material of an electric furnace and adding a composition regulating material contg. no alumina. CONSTITUTION:Metallic scraps are put in an electric furnace and subjected to oxidation refining, and after a composition regulating material is added, reduction refining is carried out. In this electric refining method, a nonaluminous material such as silica brick or dolomite brick is used as the lining refractory material of the electric furnace, and a substance contg. no alumina such as CaO, SiO2 or dolomite is added as the composition regulating material. As a result, alumina is prevented from entering produced slag, so the produced slag can be effectively used as a starting material for sintering.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrorefining method for the purpose of reforming slag generated in the electrorefining method.

[Conventional technology]

Conventionally, scrap and the like have generally been melted in an electric furnace to produce steel. An example of the electric furnace according to the conventional example is shown in FIG. 1. As shown in FIG. It is configured by arranging.

Then, the scrap put into this electric furnace 10,
Oxidation refining was performed using electric power supplied through the electrode 13, and then the slag was drained, and a predetermined component refining material was introduced to perform reduction refining.

(Problems to be Solved by the Invention) However, in the past, alumina-based bricks have been mainly used for the refractory furnace material 11 that is the lining of electric furnaces, and furthermore, aluminum, truer, etc. have been used as the above-mentioned component tempered materials. Because we used aluminum ash and alumina award-winning material,
Alumina (Altos) is added to slag (especially slag in the reduction stage).
) was a problem in that it contained 4 to 9%.

For this reason, even though the above slag has a high lime content,
There was a problem in that it could not be used as an auxiliary raw material for steelmaking (for example, a raw material for sintering, which is a pretreatment process in a blast furnace).

If left as is, it may cause disintegration, so the rest of the material, which was used in fillers and the like, was discarded.

The present invention was made in view of these circumstances, and reduces the alumina content in the slag produced in an electric furnace.
The purpose of the present invention is to provide an electrorefining method for the purpose of slag reforming that can also be used as a raw material for sintering, which is a blast furnace pretreatment process.

[Means to solve problems]

The electrorefining method for the purpose of slag reforming according to the method of the present invention, which meets the above objectives, involves charging metal scrap into an electric furnace lined with refractory furnace material, oxidizing and refining it, and then adding component tempered material to the electric furnace. In the electric refining method, which performs reduction refining by charging, a non-alumina brick is used as the refractory furnace material, and a component tempering material that does not contain alumina is used as the component tempering material that is charged into the electric furnace. ing.

Here, non-alumina refractory furnace materials include silica bricks, dolomite bricks, magnesia bricks, zirconia bricks, lime bricks, chrome bricks, carbonaceous bricks, silicon carbide bricks, and silicon carbide.
C
It refers to aO, Stow, dolomite, magnesite, etc.

[Effect]

The electrorefining method for the purpose of slag reforming according to the present invention uses a material that does not contain alumina as a component refining material. Therefore, during refining (particularly during the reduction period), no alumina particles come in from the component tempered material.

Next, since the lining of the electric furnace is made of a non-alumina refractory material, no alumina will be mixed into the slag from the furnace material during refining.

〔Example〕

Next, an example embodying the present invention will be described to provide an understanding of the present invention.

First, when manufacturing or repairing an electric furnace, non-alumina bricks are used for the refractory lining. Examples of non-alumina bricks include silica bricks, dolomite bricks, and magnesia bricks as described above. , zirconia bricks, lime bricks, chrome bricks, carbonaceous bricks, silicon carbide bricks, silicon carbide-graphite bricks, silicon nitride bricks or magnesia-carbon bricks are preferably used.

In this case, the gutter and ladle, which are equipment attached to the electric furnace, are also made of non-alumina refractory furnace material (including regular furnace material and irregular furnace material).

As a result, even after the slag is discharged from the electric furnace, alumina will not be mixed in from the ladle or gutter.

After constructing the electric furnace in this manner, scrap is placed in the electric furnace, and electricity is supplied through the electrodes to melt the scrap and perform oxidation refining.

Even in this oxidation refining, since the electric furnace is lined with a non-alumina refractory furnace material, slag with a low alumina content is produced.

After this, the slag floating on top of the molten steel is removed, and then the composition-refined material is added. This component-refined material has CaO as its main component, and calcined dolomite, uncalcined dolomite, and magnesite are added if necessary.

Since the above component-refined materials are non-aluminous, alumina will not be mixed into the slag during reduction refining.

Thereafter, after completing the predetermined refining work, the slag in the reduction period is discharged, and the steel that has undergone the predetermined treatment is also discharged to complete the refining.

The above-mentioned slag in the reducing stage is slowly cooled and then crushed if necessary to be used as a raw material for the above-mentioned sintering.

The reason why pulverization is necessary here is because the slag in the reduction stage will naturally disintegrate if left alone, so there is no particular need to do so unless it is urgent. In addition, as another method, it is also possible to treat the slag in the reduction stage, which has been slaged off, to make it into sand, and then further crush it to use it as a sintering raw material.

Next, Table 1 shows an example of the components of the slag in the reduction period according to the conventional example and an example of the components of the slag in the reduction period (i.e., sintering raw material) produced by the method of the present invention.

In the table, A and B indicate the slag in the reduction period according to the conventional example, and C and D indicate the slag in the reduction period treated by the method of the present invention.

Table 1: Units are % by weight As shown in Table 1, it can be seen that the slag in the reduction stage produced by the method of the present invention has an AbOi of 3% or less and a lime content of approximately 55%. .

Therefore, it can be fully used as a raw material for the above-mentioned sintering raw material, especially as a lime source.

Next, an experimental example in which the sintered raw material produced by the method of the present invention was used for sintering, which is a step of actual blast furnace pretreatment, will be explained.

Table 2 shows the materials used as raw materials for this sintering and the sintering conditions.

Table 2 Unit Weight % In the above, slag refers to the sintering raw material produced by one embodiment of the method of the present invention, and coke refers to the percentage of external cutting.

The results of this sintering are shown in Table 3.

Table 3 As can be seen from this table, even if the sintering raw material produced by the method of the present invention is used instead of limestone, productivity, product yield, and strength can be obtained that are approximately equivalent to the sintering process using materials produced by the conventional method. I can do it.

Therefore, it can be seen that the reducing material slag produced by the method of the present invention can be used satisfactorily as a raw material for sintering.

〔Effect of the invention〕

The present invention is constructed as described above, and uses a non-alumina material for the refractory furnace material, and also uses a component tempered material that does not contain alumina for the component tempered material. By selecting and using a material with a low aluminum content, it is possible to make the slag in the reduction period low in alumina, and thereby it is possible to use the slag in the reduction period as a raw material for sintering.

This makes it possible to effectively use the reduction stage slag, which was conventionally disposed of, as a raw material for sintering.

Furthermore, according to the present invention, since slag can be used as a sintering raw material, there is no need to supply lime during sintering.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional electric furnace. Patent applicant: Japan Magnetic Separation Co., Ltd. Patent attorney: Fujio Nakamae (and two others)

Claims (4)

[Claims] (1) In the electric refining method, in which metal scrap is charged into an electric furnace lined with refractory furnace material and oxidized and refined, and then component tempered material is charged and reductively refined, the refractory furnace material is non-aluminated. An electro-refining method for the purpose of reforming slag, characterized in that a quality brick is used and a component tempering material that does not contain alumina is used as a component tempering material that is charged into the electric furnace. (2) Refractory furnace materials are silica bricks, dolomite bricks, magnesia bricks, zirconia bricks, lime bricks, chrome bricks, carbonaceous bricks, silicon carbide bricks, silicon carbide-graphite bricks, silicon nitride bricks, or magnesia-carbon bricks. An electrorefining method for the purpose of reforming slag according to claim 1. (3) Claim 1 or 2, wherein the component tempered material is CaO, SiO_2, dolomite, or magnesite.
Electrorefining method for the purpose of slag reforming as described in Section 1. (4) The slag produced by the electric furnace is crushed and then used as a raw material for sintering.
An electrorefining method for the purpose of slag reforming as described in item 1 or 3.