JPH10141866A - Laying method for unshaped refractory for lining of ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a construction body capable of filling a fluidized material consisting of an unshaped refractory in a high density at the site and besides which has high durability, in a method suitable for constructing the lining of a ladle for secondary refining at the site. SOLUTION: A construction body is made by filling a ladle construction frame with a fluidized material consisting of an unshaped refractory whose usable time is adjusted to two hours or over, and the ladle can itself including the construction body is evacuated with a vacuum treatment device within the usable time. As the vacuum treatment device, the device usually used for treating molten steel (for secondary refining) is used, and as the ladle construction frame, a construction frame made of steel with a hole, a construction frame consisting of the net made of steel, or a construction frame made of steel fitted with a stuck ceramic fiber is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of installing a refractory for lining a ladle (steel container) in the steel industry, and more particularly to a method for installing a ladle for secondary refining on site. The present invention relates to a construction method which is capable of filling a high-density castable material made of an amorphous refractory at a site and forming a construction body having high durability.

[0002]

2. Description of the Related Art Conventionally, in order to cope with the needs of smelting of high-grade steel, secondary refining processing such as LF (Ladle Furnace) processing and vacuum degassing processing has been performed in a molten steel ladle. As a lining material for the ladle for the secondary refining process, magnesia-carbon brick (regular refractory) is commonly used as a material that can withstand high heat and a long refining process. I have.

However, in order to save labor and manpower in the furnace construction work in recent years, the application of "irregular refractories capable of mechanizing a furnace" instead of the above-mentioned fixed refractories has been pursued. As an irregular-shaped refractory for ladle lining having high corrosion resistance, a casting material (magnesia casting material) utilizing magnesia raw material has been studied.

[0004] As a method of applying the pouring material,
A casting frame is placed in a ladle can body with a built-in furnace, and a magnesia-based casting material is poured into the working frame, and then a bar-shaped vibrator or a vibrator attached to the working frame is operated and tightened. It is a method of hardening. However, this construction method has a disadvantage that the packing density of the construction body is low, and therefore, the corrosion resistance, the structural spoiling property, the erosion resistance and the like are insufficient, and the conventional magnesia cap described above is insufficient. -The durability was remarkably inferior to that of the bon brick (regular refractory).

Therefore, conventionally, as a construction method for obtaining a dense construction body (molded body) by improving the filling density of the casting material, (1) an irregular refractory between an outer shell iron plate and an inner frame of a molten metal vessel; , And the pressure is reduced through a vacuum mat fixed and held in the inner frame in advance, and a part of the added water is removed by suction.
(Japanese Patent Publication No. 56-45763), (2) A construction method in which a large number of small holes with an open top are formed in the cast material, and the material is filled by vibration and decompression (Japanese Patent Publication No. 3-54604). Gazette),
(3) In the process of preparation and construction of an amorphous refractory, a construction method in which the injection path reaching the molded frame after preparation by the kneader is a vacuum atmosphere (Japanese Patent Publication No. 7-84988), (4) After the pouring material to which water has been added is passed through a sieve under reduced pressure, a construction method of filling the construction frame while vibrating on a vibration table (Japanese Patent Laid-Open No. Hei 7-232311) has been proposed. I have.

[0006]

[Problems to be Solved by the Invention] By the way, the above (1) to
The construction method of (4) was developed for small and small precast blocks. for that reason,
If you try to apply the above (1) to (4) construction methods on site and to large equipment like a (molten steel) ladle used for refining processing, that is, large on-site construction like ladle lining However, there is a problem that it is not sufficient in terms of handling and that it requires a large investment in construction equipment.

That is, in the construction methods (1), (3) and (4), the construction equipment becomes large, and the general pouring construction equipment is used.
Requires 2 to 3 times more capital investment than (device).
Further, in the construction method of the above (2), handling becomes complicated. Furthermore, in the construction methods of the above (1) to (4), the water content decreases during the transportation of the casting material, and the flowability decreases in order to build a large construction body such as a ladle. There was a problem that construction problems occurred.

[0008] The present invention has been made in view of the above problems, and an object of the present invention is to provide a refractory for lining a ladle, which can build a denser construction body at a use site. It is an object of the present invention to provide a construction method. In addition, the present invention increases the packing density of a construction body that is cast by casting a casting material into a construction frame for lining a ladle, in other words, by reducing the apparent porosity, the durability of the ladle is increased. An object of the present invention is to provide a construction method of a refractory for ladle lining which can be improved and is suitable for construction on site.

[0009]

Means for Solving the Problems The inventors of the present invention have been keen to construct a castable material having a durability comparable to that of conventional magnesia-carbon brick (regular refractory) by on-site construction. As a result of repeated studies, the present invention has been completed. That is, the ladle lining according to the present invention is a method for forming an amorphous refractory for lining a ladle, into a ladle construction frame, charging and charging a casting material comprising an amorphous refractory with a pot life of 2 hours or more. Forming a construction body, and ladle can itself including the construction body is decompressed by a vacuum processing device within the pot life (claim 1),
Wherein the vacuum processing apparatus is normally used for molten steel processing (for secondary refining) (claim 2).

[0010] Further, as the ladle construction frame, a construction frame in which holes having a hole diameter of 2 to 10 mm are arranged at a pitch of 1 m or less (claim 3); a construction frame made of a steel net (Claim 4), and furthermore, a construction frame in which a ceramic fiber woven or nonwoven fabric having a thickness of 2 mm or more is adhered to the construction surface side of the casting material of the ladle construction frame. (Claim 5). A method for constructing a refractory for ladle lining, the method comprising:

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below. The construction method according to the present invention is particularly suitable for constructing a secondary refining ladle on-site.

By the way, in the ladle for secondary refining, the refractory for lining the ladle is exposed to severe use conditions because the ladle is subjected to a long-time treatment at a high temperature. When using a cast material (amorphous refractory) as this refractory, in order to obtain a durability comparable to that of conventional magnesia-carbon brick (a regular refractory), a dense construction body must be used on site. It is necessary to build a furnace.

Accordingly, the present invention specifically relates to a ladle can and a casting material (construction body) charged and filled in a construction frame in advance in a vacuum processing apparatus used as a secondary refining apparatus.
It is characterized in that the construction body and the construction frame are housed and decompressed within the usable time, and that the decompression process removes bubbles in the construction body and obtains a dense construction body.

As a construction frame, in order to promote deaeration during depressurization, a construction frame in which holes having a diameter of 2 to 10 mm are arranged at a pitch of 1 m or less or a steel net (punching metal,
It is preferable to use a construction frame using expanded metal. In the above construction frame, the hole or net width for promoting degassing during decompression is sufficient as long as the casting material does not leak during construction, and in the case of a commonly used casting material,
There is no problem with a hole or net width of 10 mm, but this is 2 m.
If less than m, the decompression effect at the time of decompression processing in the vacuum processing device will be the same as the construction frame without holes,
It is not preferable because deaeration is difficult.

[0015] Further, in order to promote deaeration from the gap between the casting construction body and the construction frame, a construction frame having a highly permeable ceramic fiber woven or nonwoven fabric attached to the construction surface side of the casting material is also used. Can be. The thickness of the ceramic fiber-woven fabric or nonwoven fabric is desirably 2 mm or more. If the thickness is less than 2 mm, the woven fabric or nonwoven fabric is crushed by the casting material, the gap between the construction body and the construction frame is reduced, and it is difficult to deaerate. Not preferred.

[0016] In the construction method according to the present invention, first, 4-8% by weight of water is added to a casting material whose pot life is adjusted to 2 hours or more.
It is added, kneaded, and charged and filled into a construction frame to form a construction body. If the pot life is less than 2 hours, the poured material starts to aggregate during the construction, and the deaeration becomes insufficient even if the pressure reduction treatment is performed, which is not preferable. The upper limit of the pot life is not particularly limited in the present invention, but is preferably within 15 hours. The reason is that in the case of a pot life of 15 hours or more, it takes a long time to remove the construction frame, which may cause a problem on the ladle operation side. The working time means a working time (workable time) or a fluidity maintenance time.

When the casting material is charged into the construction frame,
In order to obtain a sufficient filling property, it is preferable to use a urethane motor, a rod-shaped vibrator, a plate-shaped vibrator or the like in combination. Immediately after being charged and filled in the construction frame, the ladle cans are housed together in a vacuum processing device (a vacuum processing device used as a secondary refining device) and subjected to a reduced pressure treatment under a reduced pressure of 380 torr or less. Even during the decompression treatment, it is preferable to provide a vibration motor by arranging, for example, a urasu motor on the construction frame, and it is desirable because a further densification effect is produced.

In the present invention, the pouring material (amorphous refractory) is not particularly limited, but an alumina / magnesia pouring material or a magnesia / carbon pouring material can be used.

[0019]

Next, examples of the present invention will be described together with comparative examples.
The construction method according to the present invention will be described in more detail.

(Examples 1 to 8 and Comparative Examples 1 and 2) Changes in "apparent porosity of a construction body (cast material) from the construction frame surface to the back" when various steel construction frames are used Examined. The results are shown in FIGS.

The following (1) to (4) were used as construction frames.
(See FIGS. 1 and 2). (1) Normal steel construction frame (2) Perforated steel construction frame (hole diameter: 3 mm, pitch: 500 mm) (3) Construction frame made of steel net (net width: 5 mm) (4) Ceramic fiber-attached Steel plate (fiber
(Thickness: 5mm)

The ladle lining work was performed as follows.
The construction frame of (1) to (4) above is arranged in the ladle can, and in this construction frame, the alumina / magnesia pouring material applied to the general wall and the slag line are applied. And two kinds of magnesia and carbonaceous pouring materials were charged and filled, and the ladle cans were immediately accommodated in a vacuum processing apparatus and cured under reduced pressure at 100 torr for 1 hour (Examples 1 to 8).
For comparison, a case was also conducted in which the composition was simply cured under the atmospheric pressure without using the above vacuum processing apparatus (Comparative Example 1,
2). The alumina-magnesia used in Examples 1 to 4 and Comparative Example 1 shown in FIG. 1 and Example 5 shown in FIG.
Table 1 shows the chemical composition, working water content, and pot life of the magnesia-carbonaceous casting material used in Comparative Examples 2 to 8.

[0023]

[Table 1]

From FIGS. 1 and 2, the construction method according to the present invention is shown.
The construction body obtained by (method of decompressing the ladle can body filled with the pouring material using a vacuum treatment device using various construction frames)
The apparent porosity tends to increase gradually in the direction of the can (steel) from the exposed surface (operating surface), but the apparent porosity, as a whole, no matter which construction frame is used It was found to be low (Examples 1 to 8). On the other hand, in Comparative Examples 1 and 2, which were cured under the atmospheric pressure without performing the decompression treatment,
It was found that the apparent porosity was large and not dense as compared with Examples 1 and 5.

(Examples 9 to 17, Comparative Examples 3 and 4) The erosion resistance and the erosion resistance of a construction body when lining construction is performed by changing the construction moisture content, pot life, steel construction frame, degree of vacuum during curing, etc. The durability of the ladle was examined. Here, all are examples performed using a 20-ton ladle for secondary refining.

Amorphous refractories consisting of the chemical components shown in Table 2
(Poured material) was prepared and subjected to construction adjustment (construction water content, usable time) as shown in Table 2, and then put into a construction frame shown in Table 2. This was immediately stored in a vacuum processing apparatus together with the ladle can, and was similarly cured under reduced pressure shown in Table 2 for 1 hour (Examples 9 to 17). Table 2 shows the ladle life (ch) and the maximum damage depth (mm / ch) in this case. Note that, for comparison, a test was also carried out on curing under atmospheric pressure.
(Comparative Examples 3 and 4).

[0027]

[Table 2]

From Table 2 above, in Examples 9 to 17 according to the construction method of the present invention, the life of the ladle for secondary refining is 40 to 65 c.
h, the maximum damage depth was 1.5 to 2.5 mm / ch, and it was found that the material had properties comparable to those of conventional magnesia-carbon brick. On the other hand, in Comparative Examples 3 and 4 using only atmospheric pressure curing, the ladle life was 25 ch, 35 c
h, the maximum damage depths were 4.0 mm / ch and 2.9 mm / ch, which were significantly inferior to the corresponding Examples 9 and 12.

[0029]

According to the present invention, as described in detail above, a casting material composed of an irregular-shaped refractory whose pot life is adjusted to 2 to 10 hours is charged and filled into a ladle construction frame. Forming
The ladle can itself including the construction body is subjected to a reduced pressure treatment by a vacuum treatment device within the pot life, thereby increasing the packing density of the construction body and reducing the apparent porosity. Thereby, the durability of the ladle can be improved, and the effect of having a durability comparable to that of the conventional magnesia-carbon brick (regular refractory) is produced. Further, according to the present invention, the vacuum processing apparatus used as the current molten steel processing apparatus can be used as it is, so that no capital investment is required for the decompression treatment, and the furnace is built on site. Can have the advantages.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in “apparent porosity of a construction body (cast material) from the construction frame surface to the back” when various steel construction frames are used, and Comparative Example 1
FIG.

FIG. 2 is a view similar to FIG. 1, showing Examples 5 to 8 and Comparative Example 2.

Continued on the front page (72) Inventor Toshihiko Kanaeshi 873 Ibe, Bizen-shi, Okayama Prefecture (72) Inventor Yuichi Takakura 390, Higashi-Katagami, Bizen-shi, Okayama Prefecture (72) Inventor Yukiharu Tabuchi 732, Nishikataoka 732, Okayama Prefecture Okayama Prefecture (72) Inventor Sugihara Tadashi 1110-3 Asagiri Kitamachi, Akashi City, Hyogo Prefecture

Claims (5)

[Claims] 1. A ladle can body including a ladle construction frame, wherein a casting material made of an amorphous refractory having a pot life of at least 2 hours is charged and filled into a ladle construction frame to form a construction body. A method for constructing a refractory for ladle lining, wherein the refractory itself is subjected to a reduced pressure treatment by a vacuum treatment device within the pot life. 2. The method according to claim 1, wherein the vacuum processing apparatus is a vacuum processing apparatus generally used as a secondary refining apparatus. 3. The ladle construction frame, wherein a hole diameter is 2 to 10 m.
The construction method of the refractory for ladle lining according to claim 1, wherein a construction frame in which m holes are arranged at a pitch of 1 m or less is used. 4. The method according to claim 1, wherein a construction frame made of a steel net is used as the ladle construction frame. 5. A laminating frame comprising a ceramic fiber woven fabric or a non-woven fabric having a thickness of 2 mm or more attached to the ladle laminating frame on the side of the pouring material. The construction method of the irregular shaped refractory for ladle lining described.