JPH0656538A - Molding for joint - Google Patents

Abstract

PURPOSE:To obviate the generation of hot spalling when the hot molding for a joint is mounted to nozzle refractories. CONSTITUTION:This molding 5 for the joint is constituted of 40 to 90wt.% refractory material and 10 to 60wt.% binder based on total 100wt.% of the compounding compsn., is molded to the molding of a shape corresponding to the joint between an immersion nozzle 3 and tuyere brick 2 to be joined and exhibits plasticity by the heat retained by the immersion nozzle 3 when mounted to the outer peripheral part of the immersion nozzle 3 at the time of exchanging the immersion nozzle 3. The binder consists of a combination of at least one kind of a thermoplastic resin, thermosetting resin and pitch and at least one kind of either of blown asphalt and bojuntan.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint molding which is filled between a nozzle refractory and a tuyere refractory to form a joint, and which is capable of joining the nozzle refractory to the tuyere refractory. is there.

[0002]

2. Description of the Related Art There are long nozzles and immersion nozzles as nozzle refractories used in continuous casting operation of steel. Here, immersion nozzles will be described. This immersion nozzle connects the two so as to supply molten steel from the tundish to the mold, and is attached to the tuyere of the tundish. A joint material is filled between the tuyere and the dipping nozzle in order to prevent accidents such as so-called molten metal leak in which molten steel enters between the tuyere and the dipping nozzle. Usually, such a joint material is composed of mortar that has been kneaded with water, and after applying this mortar to the tuyere joint of the dipping nozzle with a predetermined thickness by hand etc. and mounting the dipping nozzle on the tuyere, the tundish And the joint is formed by preheating the immersion nozzle to a predetermined temperature. The joint joins the tundish and the dipping nozzle.

In the continuous casting operation, the molten steel solidifies between the tundish, the dipping nozzle and the mold, and it is important to prevent contamination of the molten steel. Therefore, the tundish and the dipping nozzle are used as one unit, and usually after continuous casting of 5 to 10 charges of the same steel type, it is discarded together with the change of steel type.

However, it is not desirable in terms of cost to discard and replace the tundish and the dipping nozzle each time the type of steel is changed. Continuous use of dishes is being considered.

In this case, the tundish has a life of 100.
The life of the immersion nozzle is short compared to the expectation for charging or more, and it is necessary to replace the immersion nozzle with 5 to 10 charges. It should be noted that the replacement of the immersion nozzle is preferably performed hot from the viewpoints of energy saving, shortening of operation time, and the like. However, the preheating temperature of the immersion nozzle is 70
It is impossible to apply water-mixed mortar to the immersion nozzle at a temperature of 0 to 1200 ° C, and if the normal temperature immersion nozzle with mortar is attached to a hot tundish, the immersion nozzle will spall. In order to join the immersion nozzle to the tundish by the above-mentioned conventional method, the tundish must be once cooled to near room temperature. Therefore, in the replacement of the immersion nozzle by the conventional joining method, a loss of energy during cooling the tundish and heating it to the operating temperature again, and a loss of time during that period are unavoidable, which contributes to energy saving and shortening of operating time. There was a problem of being contrary.

In order to advantageously solve this problem, the present inventors have proposed the following joint molding in Japanese Patent Application No. 3-320613. Since this joint molded body enables insertion and joining of a nozzle refractory such as a dipping nozzle into a tuyere refractory while hot, the total amount of the compounding composition is 1
A molded body having a shape corresponding to the joint between the nozzle refractory and the tuyere refractory to be joined, which is composed of 40 to 90 wt% of the refractory material out of 00 wt% and 10 to 60 wt% of the binder. When the nozzle refractory is replaced, the nozzle refractory is mounted on the outer periphery of the upper portion of the nozzle refractory and exhibits plasticity due to the heat retained by the nozzle refractory.

A joint molded body formed into a shape corresponding to a joint between a nozzle refractory and a tuyere refractory to be joined is
The nozzle refractory, which has been preheated to 700 to 1200 ° C., is mounted on the outer peripheral portion of the upper portion of the nozzle refractory and is plasticized by the retained heat of the nozzle refractory. Then, the nozzle refractory is inserted and joined into the tuyere refractory in the plasticized state of the joint molding. In this way, the joint molding is filled between the nozzle refractory and the tuyere refractory, and the joint molding becomes hot-fired and eroded by molten steel, slag, etc. ， Forms fine joints that resist abrasion, and firmly joins the nozzle refractory to the tuyere refractory.

The refractory material used here is alumina,
In addition to magnesia, silica, zirconia, zircon, titania, bauxite, granite, wax stone, etc., carbonaceous materials such as phosphorous graphite, earthy graphite and coke are also used together. In addition, the joint molding is 700 to 1200 at room temperature.
Since it is mounted on a nozzle refractory at a high temperature of ℃, phosphorous graphite is usually added to the joint molding in order to prevent the joint molding from cracking due to hot spalling.

[0009]

As described above, in order to obtain the spalling resistance of the joint molded body, 10 to 30 wt% of carbonaceous material such as phosphorous graphite is usually added to the joint molded body. When the carbonaceous material is less than 10 wt%, when the joint molded body is mounted on the preheated nozzle refractory, the joint molded body may be cracked and fallen off by thermal spalling. Further, even when the nozzle refractory is inserted into the tuyere, if the joint molding is cracked by the heat spalling, problems such as molten metal leakage will occur.
However, in molten steel such as electromagnetic steel in which a large amount of oxygen is contained in the steel and the viscosity is low, carbon in the composition is oxidized by oxygen in the steel and eroded, so that the molten steel penetrates into the joints. There were many cases where hot water leaked.

[0010]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the joint molding according to the present invention is basically a refractory material in a total amount of 100 wt% of the composition.
40 to 90 wt% and a binder; 10 to 60 wt% and molded into a molded body having a shape corresponding to a joint between a nozzle refractory and a tuyere refractory to be joined,
In a joint molding which is attached to the upper outer peripheral portion of the nozzle refractory at the time of replacement of the nozzle refractory and exhibits plasticity due to the retained heat of the nozzle refractory, the binder is made of thermoplastic resin, thermosetting resin, or pitch. It is characterized by being composed of a combination of at least one kind and one of blown asphalt and swelling coal.

The refractory materials used in the present invention are alumina, magnesia, silica, zirconia, zircon,
Any material that can be used as a material for mortar such as titania, bauxite, granite, wax stone, etc. may be used, and two or more kinds of these refractory materials may be mixed and used.
In general, the refractory material preferably has the same composition as the nozzle refractory and tuyere refractory to be joined. If the content of such a refractory material is less than 40 wt%, the fire resistance at the continuous casting operating temperature, the corrosion resistance to molten steel and slag, and the wear resistance are reduced, and the content of the binder is inevitably increased. When the preformed nozzle molding is mounted so as to cover the preheated nozzle refractory, the joint molding is excessively plasticized by the heat retained by the nozzle refractory and flows down by its own weight. Further, if it exceeds 90 wt%, the amount of the binder to be blended will inevitably decrease, so that the plasticization due to the retained heat of the preheated nozzle refractory becomes insufficient and filling as a joint material when set in the tuyere refractory. Sex deteriorates. Carbonaceous materials such as phosphorus-like graphite, earth-like graphite, and coke are also refractory materials, but in view of corrosion resistance to molten steel, it is preferable not to use it if it is preferable that the amount is small.

According to the experiments conducted by the present inventors, when the amount of phosphorus-like graphite added is less than 10 wt% at the temperature of 700 ° C. of the nozzle refractory at the time of mounting, the joint molded body is formed by thermal spalling at the same time as mounting. It was confirmed that cracks were formed and cracks occurred. For this reason, Japanese Patent Application No. 3-320613 proposes to use at least one kind of a thermoplastic resin, a thermosetting resin, and a pitch as a binder in an amount of 10 to 60 wt%.

As a result of various studies conducted by the present inventors, the binder and the swelling charcoal or blown asphalt were combined and added to the joint molding to obtain a composition in the joint molding. It was found that hot spalling does not occur when the joint molded body is hot mounted on the nozzle refractory even if the carbonaceous material such as phosphorous graphite is not contained in.

The swollen coal is obtained by adding a tar-based solvent to finely pulverized coal and heating it at 300 ° C. under normal pressure (Chemical Handbook, edited by the Chemical Society of Japan, revised edition 3 (198).
0) Maruzen p. 712) Especially used for paving materials and anticorrosion paints. Further, blown asphalt is an asphalt obtained by blowing a vacuum distillation residue of crude oil. Further, the thermoplastic resin, thermosetting resin, and pitch described above are solidified at room temperature and cracked by a slight stress, whereas swelling carbon and blown asphalt have viscoelasticity and are flexible to stress. .

In the present invention, the refractory material; 40 to 90 wt% and the binder;
It is composed of 60 wt% and is formed into a molded body having a shape corresponding to the joint between the nozzle refractory and the tuyere refractory to be joined. In a joint molding that is attached and exhibits plasticity due to the heat retained by the nozzle refractory, at least one of a thermoplastic resin, a thermosetting resin, and pitch, and any one of swelling charcoal and blown asphalt are used as a binder. By combining them, a joint molding having excellent spalling resistance is obtained.

In order to adjust the hot fluidity of the joint material, a thermosetting resin such as a phenol resin having a high residual carbon content may be used in combination as one of the binders. In addition, this thermosetting resin has a preferable compounding amount of the binder of 10 to 60 w.
In t%, the ratio of the thermoplastic resin and / or the pitch to the thermosetting resin may be 90/10 to 10/90, preferably 80/20 to 40/60. In addition, it is preferable to add 0.1 to 10 wt% of carbon fiber by external coating to 100 wt% of the total amount of the blended composition, and the strength as a molded body and a joint material is increased due to the rasping effect. If the amount of such carbon fibers added is less than 0.1 wt%, the effect of increasing the strength is small, and if it exceeds 10 wt%, it becomes difficult to uniformly knead the mixture during molding.

[0017]

The joint molded body formed into a shape corresponding to the joint between the nozzle refractory and the tuyere refractory to be joined is mounted on the outer peripheral portion of the upper portion of the nozzle refractory to be preheated, and the nozzle refractory is attached. It is plasticized by the heat it retains. At this time, if the compounded refractory material does not include a carbon-based material such as phosphorous graphite, the joint molding formed on the nozzle refractory is rapidly heated to cause thermal spalling. In addition, when the binder is composed only of thermoplastic resin, thermosetting resin, pitch, etc. as in the conventional case and the joint molding containing the binder is solidified, the joint molding behaves as an elastic body. To do. However, in the present invention, since the binder and the swelling charcoal or blown asphalt are combined and added to the joint molding, the joint molding acts as a viscoelastic body and is flexible to the load of thermal stress. In addition to possessing high ability, it has high spalling resistance and prevents cracking.

Next, the nozzle refractory is inserted and joined into the tuyere refractory in the plasticized state of the joint molding. In this way, the joint molding is filled between these nozzle refractory and tuyere refractory,
This joint molded body is fired in a hot state to form a dense joint that resists corrosion and wear of molten steel, slag, etc., and firmly joins the nozzle refractory to the tuyere refractory.

Since a series of steps from the above-mentioned setting of the joint molding to the formation of the fine joints are carried out hot, the tundish is cooled even when the immersion nozzle connected to the tundish is replaced, for example. There is no need to do it, and replacement is done promptly.

Since the joint molding of the present invention has a shape-retaining property of moderate strength at room temperature, it can be smoothly mounted on the nozzle refractory without being damaged by the handling by the robot and can be hot-worked. Easy to operate. Also,
While hot, it exhibits an appropriate degree of plasticity and smoothly fills the joint site.

[0021]

EXAMPLES Next, specific examples of the joint molding according to the present invention will be described with reference to the drawings and tables.

Alumina powder as a refractory material, thermoplastic phenolic resin (novolac resin containing almost no hexamine) as a thermoplastic resin, thermosetting phenolic resin as a thermosetting resin, coal pitch powder as a pitch, blown asphalt, Each material of swelling carbon and carbon fiber was prepared at the compounding ratio shown in Table 1. Since it is difficult to make swelling charcoal or blown asphalt into powder, the swelling charcoal or blown asphalt is preliminarily treated with alumina powder in advance.
After melting and mixing at about 0 ° C., it is desirable to mix the remaining thermoplastic phenol resin, thermosetting phenol resin and coal pitch powder with a Hensinil mixer to prepare a joint material.

The joint material prepared in this manner is used for 150
After heating to ℃ to impart fluidity, as shown in FIGS. 1 and 2, between the tuyere brick 2 as the tuyere refractory of the tundish 1 and the dipping nozzle 3 as the nozzle refractory. No. 1 to No. 5 was obtained by pressure molding into a shape corresponding to the joint and having the collar 4 on the upper portion, and after cooling and drying. In order to reliably fill the joint material, it is desirable that the joint molded body 5 has a thickness slightly larger than the joint between the tuyere brick 2 and the dipping nozzle 3 to be joined. Further, as comparative examples, joint moldings (No. 6 to No. 8) in which the compounding ratio of each material deviates from the range of the present invention were prepared, and the compounding ratios thereof are also shown in Table 1.

Table 1 shows 100 joint moldings.
The presence or absence of cracks when mounted on the immersion nozzle 3 preheated to 0 ° C. is shown.

[0025]

[Table 1]

The joint molded body 5 produced as described above.
2 hours after the molded joint material 5 is plasticized and softened by the heat retained by the immersion nozzle 3, it is hot inserted into the tuyere brick 2 of the tundish 1. After mounting and joining them, no cracks due to hot spalling occurred in the joint molding of the present invention. Then, the present invention example No. 1 is 6 charges, No. 2 and No. No. 4 is 8 charges, No. 4 Three
And No. In No. 5, when 9-charge continuous casting was performed, no molten metal leak occurred. Further, when the dipping nozzle 3 was removed from the tundish 1 after the end of the continuous casting and the joints were visually observed, good results were obtained without any penetration of molten steel.

Although coal pitch powder is used as the pitch in this embodiment, petroleum pitch, high residual coal pitch having a high mesophase content, or the like can also be used.

[0028]

According to the present invention constituted as described above, a binder and a swelling charcoal or blown asphalt are combined and added to the joint molding, whereby the joint molding is hot-rolled. No thermal spalling occurs when the nozzle molding is mounted on a refractory material even if the compound composition of the joint molding does not contain a carbonaceous material such as phosphorous graphite.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a joint molding and a dipping nozzle according to the present invention mounted on a tundish.

FIG. 2 is an external perspective view of a joint molding according to the present invention.

[Explanation of code] 1 Tundish 2 Tuyere brick 3 Immersion nozzle 4 Tsuba 5 Joint molding

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yoichi Yokoyama 1-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Harima Ceramic Co., Ltd. (72) Tatsuo Okada 1-2-1 Omachi, Hirohata-ku, Himeji-shi Stock company Okada Shokai

Claims (2)

[Claims] 1. A refractory material; 40 to 90 wt% and a binder; 10 to 60 w in a total amount of 100 wt% of a composition.
t% and is molded into a molded body having a shape corresponding to the joint between the nozzle refractory and the tuyere refractory to be joined. In a joint molding which is attached and exhibits plasticity due to the retained heat of the nozzle refractory, the binder is at least one of a thermoplastic resin, a thermosetting resin, and pitch, and one of blown asphalt and swelling charcoal. A joint molding, which is characterized by comprising a combination of 2. The joint molding according to claim 1, wherein the carbon fiber; 0.1 to 10 wt% is added to the total amount of the blended composition of 100 wt% by external coating.