JPS6030721B2 - Method for treating lining material of containers for hot metal pretreatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for lining a container for transporting and/or storing molten pig iron (hereinafter referred to as "container") for pre-treating molten pig iron.

Pretreatment is the process of removing sulfur and/or poppy, elemental material, and/or phosphorus from molten pig iron produced in a blast furnace (hereinafter referred to as "hot metal") before refining it in a steelmaking furnace such as a converter. Refers to processing.

Silica-alumina fired bricks have been mainly used for conventionally used containers due to the need for blast furnace slag resistance and heat spall resistance.

However, in the pretreatment, sodium compounds, calcium compounds, iron compounds, etc. are used, so the slag after the pretreatment (hereinafter referred to as "pretreatment slag") has characteristics such as basicity and iron oxide concentration that are similar to blast furnace slag. The silica-alumina fired bricks are completely different from each other, so the silica-alumina fired bricks are melt-covered. Furthermore, basic bricks such as maguro-based bricks and spinel-based bricks have a large coefficient of thermal expansion and a large infiltration of calcium compounds, so spalling occurs violently.
In addition, aluminous bricks are similar to basic bricks,
In addition, carbon-containing unfired bricks such as magnesia carbon unfired bricks and alumina carbon unfired bricks are subject to severe oxidation, so they are not suitable for practical use. In view of the above-mentioned conventional drawbacks, the present invention provides a method for treating a container lining material suitable for preliminary treatment.

As shown in FIG. 1, the structure of the container is such that the inside of an iron shell 1 is lined with a suitable refractory 2, the inside is lined with a refractory 3 containing black 9ji, charcoal charcoal, and base. Preferably, an antioxidant 4 is applied as shown in FIG. However, the function of the container is that after it is constructed as shown in FIG. 1 or 2, it is prefired, and then the main firing is performed by the Nada heat of the hot metal, and the pretreated slag and the refractory 3 are reacted. Then, as shown in FIG. 3, a treated coating 5 is formed on the surface of the refractory 3, thereby completing the process. Nucleus pre-calcination is a process to remove substances such as water and binders that evaporate at relatively low temperatures, and to provide impact resistance and wear resistance against the hot metal flow during the first pig iron receiving, and the temperature and time are depends on the refractory composition and lining thickness.

The refractory material 3 is an unfired brick or a monolithic refractory material containing graphite, carbonized poppy, and a base material, and the refractory aggregate includes alumina, bauxite, siyamoto, sillimanite, low stone, poppy, stone, magnesia, It contains at least one of dolomite, spinel, chromite, zircon, and zirconia. It has been found through experience that when a container is lined with phosphorescent material, joint erosion is particularly severe. In order to prevent joint erosion, it is effective to make the joints as thin as possible or to scrape them completely, but since the unfired brick containing graphite, carbonized carbide, and element in the present invention has a small coefficient of thermal expansion, It can be constructed with joints or very thin joints. In addition, unstable refractories are most desirable because there are no joints. Generally, graphite is used to improve the spall resistance of refractories, lower the porosity, etc., but it is oxidized by oxidizing substances such as oxygen and iron oxide.

Once oxidized, the part becomes a porous body, the strength of which is significantly reduced, and the molten iron and slag are heavily penetrated, so it is worn out extremely quickly. As a result of many tests and studies, the inventors of the present invention discovered that silicon carbide's weak point, oxidizability, can actually be turned into an advantage. In other words, a part of the carbonized carbide added to the refractory is oxidized by oxygen in the atmosphere and/or Fe0 in the pretreated slag to become SiQ, and the Si02 becomes F in the pretreated slag.
Mineral reaction occurs with e○ and Ca0, resulting in the formation of a treated film on the refractory surface. The treated film mainly contains Ca○
;SIC2: A glassy substance made of Fe2Q, which plays the role of preventing the intrusion of oxidizing substances such as oxygen, thereby preventing the oxidation of coexisting graphite. The required amount of carbonized poppy and element is related to the amount of graphite, which is shown in Figure 4. That is,
The greater the amount of graphite to be prevented from oxidizing, the greater the amount of carbonization and element required. In the examples of the present invention, the amount of graphite and the amount of carbide were found to be effective when at least 10% or more, and no further increase in effect was observed even when 25% or more of each was added. Such quantitative effects depend on pretreatment conditions. Furthermore, carbonized poppy itself has the effect of preventing slag penetration, and as shown in Figure 5, it has an effect of preventing slag penetration by about 10%.
Although the above is remarkable, it does not pre-compromise the amount required for forming a treatment film.

By the way, in order to make the lining of the container even more effective, it is pre-fired at about 100 pi for about 2 hours to about 5 hours or more after lining, but at that point the pre-treated slag is Since it does not exist, as shown in Figure 6,
Oxidized.

The oxidized portion is almost completely consumed during the initial pretreatment, which is economically undesirable. In order to prevent this oxidation, it is necessary to coat the building with a substance that vitrifies at temperatures of 500 pm or higher (hereinafter referred to as "antioxidant") after construction and before heating. The reason for setting it to 500 qo is that almost no oxidation of graphite occurs and volatile substances in the refractory completely escape.

Many antioxidants are effective, such as those based on poppy seeds and shun soda, and their compositions do not need to be specified. After pre-firing, the container must be fired at a high temperature (hereinafter referred to as "main firing") in order to develop its strength, but in order to do this with burner heating, etc., it requires extremely large-scale equipment and a large amount of fuel. It is extremely uneconomical.

The inventor has discovered that by filling the container with molten pig iron of about 1400 ml or more, a firing effect simultaneously with the main firing can be obtained. That is, a temperature of about 1,400° C. is insufficient for heating with a burner, etc., but in the case of molten pig iron, the synergistic effect of pressure and temperature makes it possible to develop strength that can withstand practical use. Examples The processing conditions for the lining materials m to ① below are as follows {i) Preliminary firing conditions Temperature increase rate 10'0/H Maximum temperature 1000q
0 holding time mountain sun'.

} Main firing conditions A mixer car or a hot metal pot was filled with hot metal at 1450°C and left in the group. 1. Slag coating conditions The pretreated slag is tapped and the pretreated slag is coated by rotating the pig iron mixer furnace body or, in the case of hot metal steel, by spraying.

As the refractory lining of the '1' torpedo car, carbonized alumina and graphite unfired bricks were used and subjected to desulfurization treatment, and very good results were obtained as shown in Table 1.

■ As shown in Table 2, when alumina carbide and graphite monolithic refractories were used as lining refractories for hot metal pots and subjected to dephosphorization treatment, very good results were obtained, similar to usage example 1. Obtained.

'3} Magnesia carbonized poppy and graphite unfired bricks were used as the refractory lining of a torpedo car, and when they were removed and subjected to treatment, excellent results were obtained as shown in Table 3.

'4' Alumina - silicon carbide mountain graphite matrix unfired brick with poppy seeds, acid soda cost antioxidant (graphite 3 melon x%,
As shown in Table 4, as shown in Table 4, deterioration caused by acid G was almost completely prevented when a film was coated with 5% sodium silicate and 2% clay and pre-fired.

Table 1 Table 2 Table 3 ・*Concubine composition 0:15wt dormitory Sio:20″ M evening○: 60″ Table 4 *Alumina-silicon carbide-graphitic amorphous Approximately 10% sodium silicate antioxidant to refractories

[Brief explanation of the drawing]

Fig. 1 is an explanatory cross-sectional view of the container of the present invention before the formation of the treated film, Fig. 2 is an explanatory cross-sectional view of another embodiment of the container of the present invention before the formation of the treated film, and Fig. 3 is an explanatory cross-sectional view of the container of the present invention. , Figure 4 is a chart showing the relationship between the amount of graphite M required for carbonized particulate matter in refractories, and Figure 5 is a chart showing the relationship between the depth of slag penetration in the inner wall of the container and the amount of carbonized particulate matter. FIG. 6 is a chart showing the relationship between the pre-baking time and the thickness of the oxidized layer. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. After lining a refractory raw material with an unfired refractory or indefinite refractory containing graphite and silicon carbide, the refractory is pre-fired and then main-fired using the sensible heat of hot metal, Furthermore, a method for treating a lining material of a container for hot metal pretreatment, which comprises reacting with pretreatment slag to form a treated film on the surface of the refractory. 2 After lining a refractory raw material with an unfired refractory or monolithic refractory containing graphite and silicon carbide, and coating the lining surface of the refractory with a substance that vitrifies at 500°C or higher, the refractory A method for treating a lining material for a container for pre-treatment of hot metal, which comprises pre-firing a refractory, then main-firing it using the sensible heat of hot metal, and reacting with pre-treated slag to form a treated film on the surface of the refractory.