KR19980050636A - Charter Deregulation - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive molten iron deregulator that can be manufactured using steel mill by-products while having a deregulation equal to or higher than that of a conventional deregulator.

The present invention for achieving the above object is the technical gist of the cold pellet (cold-bonded pellet) and the electric furnace is a molten iron deregulation mixed in a composition ratio of about 7: 3-6: 4.

Description

Charter Deregulation

The present invention relates to a ral regulator used in the columnar deregulation process or the molten iron preliminary treatment in order to remove the silicon (Si) in the molten iron from the blast furnace plant through the molten iron manufacturing process.

The molten iron produced in the blast furnace contains 0.3-0.6wt% of silicon (Si), depending on the size of the blast furnace, the type of raw material used and the operation conditions. [Si] in these molten iron is an important heat source in the converter, which is a steelmaking process, but recently [Si] in the molten iron is 0.2wt% for the improvement of the quality of steel (low P steel production) or for the suppression of converter refractory and slag sensible heat release. The need to lower the concentration of is increased.

That is, it is possible to substitute by [C] as the steelmaking heat source, so that the concentration of [Si] is recognized as an element to be removed in the pretreatment step. For deregulation in the blast furnace preliminary treatment stage, mill scale and sintered ore are commonly used as deregulation agents, which should be oxidized and removed as shown in Equations (1) and (2) below. A material with a high oxygen potential is used.

[Si] + 2FeO (liq) = SiO ₂ (liq) + 2Fe ...... (1)

(Si 十 ⅔ Fe ₂ O ₃ (liq) = SiO ₂ (liq) + ¾ Fe ....... (2)

On the other hand, desulfurization treatment is generally carried out in a blast furnace bed (pig bed) and molten iron preliminary treatment plant as shown in FIG. That is, in the desulfurization treatment on the blast furnace column, as shown in Fig. 1A, the deregulation agent is directly added to the upper part of the molten iron drawn out from the blast furnace 1 through the runner 2, and the molten iron is placed in the repair vessel. By free falling in (3), the reaction proceeds using the stirring force by the drop energy obtained at this time. In addition, in the blast furnace column desulfurization treatment, there is also a system in which a deregulation agent is introduced through the lance 21 into the molten iron flowing through the molten iron as shown in FIG. 1 (B).

In addition to the blast furnace desulfurization treatment, there is also a desulfurization treatment performed during the preliminary treatment of the molten iron vessel such as a tilting spout and a torpedo car or an open ladle car. For example, in the preliminary treatment, the desulfurization treatment is carried out by depositing the lance 31 on the molten iron that has been repaired in the repair vessel 3 and desorbing the carrier gas and the carrier gas through the lance 3 as shown in FIG. The controlled powder is blown and stirred to de-silify.

However, mill scale and sintered ore, which are used as deregulation, are gradually used in fields that produce higher added value in other sectors in steel mills. In other words, with the advance of pretreatment technology, mill scale is actively used as the dephosphorizing agent, and the process of recovering and utilizing these iron sources from the existing processes such as sintering process is more expensive and is not recycled. Matter is needed.

Accordingly, an object of the present invention is to provide a molten iron deregulator that is more economical than conventional deregulators and can be replaced with conventional descalers such as mill scale or sintered ore.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram explaining the various desulfurization process in a steelmaking process.

2 is a time-dependent change of de-functionality for the conventional de-regulation

Figure 3 is a time-dependent change of de-functionality for the deregulation of the prior art and the present invention

In the present invention for achieving the above object in the deregulation for removing the silicon in the molten iron from the blast furnace,

The present invention relates to a molten iron deregulation comprising a cold-bonded pellet (60-70%) and an electric dust (40-30%) by weight.

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

First, representative compositions of cold-bonded pellets (hereinafter, referred to as 'CBP') and electric furnace dust used in the present invention are shown in Table 1 together with conventional mill scales and sintered ores.

The CBP used in the present invention refers to cold pellets prepared from various dust collecting dusts collected at a steelmaking or steelmaking plant, or by-products of pellets generated during pellet production, which are materials that can be easily secured in steel mills.

As shown in Table 1, the mill scale contains a large amount of FeO, so that the oxygen potential can be maintained high, and in the case of sintered ore, FeO is slightly low, but the iron content is high, and also contains a large amount of CaO. CBP, on the other hand, contains CaO and relatively high amounts of starch powder and FeO, but contains relatively high metal Fe since it is mainly obtained from the wet dust raw material generated in the steelmaking process.

CBP is usually reused in blast furnaces, etc. In order to use this alone, as shown in Table 1, an adequate oxygen potential is required, and an auxiliary material is needed to secure de-functionality while recycling T.Fe.

Accordingly, in the present invention, it is preferable to select the electric dust generated in the steel mill as an auxiliary material and to use the deregulation together with the CBP.

At this time, the electric furnace dust that can be used may be any that occurs in the electric furnace for producing ordinary steel. Electric furnace industry usually uses higher quality scrap and pig iron to manufacture hot rolled steel sheet. Therefore, electric furnace dust is composed of zinc (Zn) and other elements of impurities that are mixed in dust. It is suitable for deregulation. Preferred furnace dusts are those which contain at least about 50% by weight of iron and no more than 2% zinc.

In addition, the alkali component contained in the dust of the electric furnace is known to contribute to the suppression of slag forming caused by the deregulation process, and as a result, it can be expected to play a role as a reverse agent (FeO + Fe ₂ O ₃ ) exceeding 7O%. It can be seen that an adequate oxygen potential can be obtained at the mill scale level.

At this time, it is preferable that the mixing of CBP and the electric dust which secures the oxygen potential, which is necessary for Fe recovery due to the high amount of iron, be about 7: 3-6: 4 by weight.

When the CBP content exceeds 70% in the mixing ratio of the CBP and the electric dust, there is an advantageous side due to the high iron content, but the de-functionality may be deteriorated. Although it is excellent, there is a possibility that the Zn component or the like will increase when the component deviation of the dust is severe.

The de-regulator of the present invention thus prepared is secured more than the equivalent of the existing mill scale or sintered ore, and is particularly advantageous in terms of charter production cost because it uses by-products that need to be self-generated and recycled in steel mills.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

De-functionality was compared for each of the mill scale, sintered ore and CBP alone having the composition shown in Table 1 using an induction melting furnace. At this time, the molten iron used was a molten iron produced in a blast furnace, and had a composition of 4.7-5.0 wt% of carbon and 0.4-0.5 wt% of [Si]. The molten iron was 15 kg and 200 g of each deregulator was used. In the experiment, the reaction degree was adjusted to 1400 ± 50 ℃, and when the test temperature was reached, the change in concentration of [Si] was observed by taking five charter samples for 15 minutes after adding deregulation for each type prepared as described above. The de-functionality was compared, and the result is shown in FIG.

As shown in FIG. 2, the mill scale and the sintered ore used in the past showed a rapid de-silification reaction within 5 minutes after the initial input, and the relative [Si] reduction rate was close to 30% until 15 minutes thereafter. However, when using CBP alone, the initial reaction rate was low and the relative de-silification reaction rate up to 15 minutes was less than 1/2.

In other words, in terms of deregulation efficiency, the second highest sintered ore was the highest in the case of the mill scale with the highest T.Fe, followed by mill scale and CBP. It was estimated that even though the oxygen potential in the sintered ore was slightly lower, the quicklime contained contained facilitated the deregulation of goods, so that the solid oxygen contained was easily converted into dissolved oxygen.

Example 2

Except for the deregulation of the present invention in which CBP having a composition as shown in Table 1 and dust mixed with electricity was used, the deregulation was compared in the same manner as in Example 1, and the results are shown in FIG. In order to mainly use CBP having a large amount of generation, the deregulator of the present invention is an invention material (A) using 60% by weight of CBP and 40% by weight of electric furnace dust and an invention material consisting of 30% by weight of electric dust (B). ) Was used.

The lower limit was determined in terms of the amount of oxygen (deoxygenation efficiency) required for absolute desulfurization treatment when dust with less weight ratio was used.

As shown in Fig. 3, the relative [Si] reduction rate shows that the invention material (A) is higher than the mill scale level, and in the case of the invention material (B), the terminal efficiency is almost similar to that of the mill scale. This suggests that the material proposed in the present invention has de-competence comparable to the existing agent. In addition, similar to the sintered ore, CBP contains about 15% by weight of CaO, it is expected that the goods can be promoted to improve the efficiency of the reaction.

However, there are many concerns about scattering because it is finer than existing ones, but the process adopted by the blast furnace plant is the top injection method and the method of de-regulation in the repair vessel in advance. However, the problem with fine particles is estimated to be less than expected. That is, in the case of the upper blowing method, since the deregulation is configured for high speed blowing, a property of 1 mm or less is required, so the deregulation according to the present invention is suitable for the limited conditions, and in the case of pre-injection, the deregulation is performed together with the molten iron. Since there is no regulation, there is no concern about dusting, except for initial charging.

As described above, the deregulator of the present invention has a desorption capacity equal to or higher than that of conventional mill scales or sintered ores, and in particular, such deregulators are very expensive in terms of manufacturing cost because they use low-cost materials that are self-generated in a steel mill and require recycling It has an economic effect.

Claims (3)

Deregulation for removing silicon from molten iron from the blast furnace, wherein the molten iron is characterized in that the composition is composed of 60% to 70% cold-bonded pellets and 40% to 30% electric furnaces by weight. regulation The deregulator according to claim 1, wherein the cold pellet contains at least 50% by weight of T.Fe. The deregulator according to claim 1, wherein the electric furnace has a train weight (T.Fe) of 50 weight or more and a zinc content of 2% or less.