JP3118522B2 - Hot repair spraying material for less slag operation converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot repair spray material for a converter for performing a less slag operation.

[0002]

2. Description of the Related Art As a wet converter repair spraying material, a material which uses phosphate as a binder in a basic aggregate and utilizes the reaction hardening property of magnesia and phosphate has been widely used. I have. However, such a spraying material has a low curing speed, and the reaction product, magnesia phosphate, is Mg
O.P ₂ O ₅ (melting point: 1165 ° C.), 2MgO.P ₂ O ₅ (melting point: 1332 ° C.), 3MgO.P ₂ O ₅ (melting point: 1357)
C), and has a low melting point, which is not preferable.

[0003] In addition, as a dry converter repair spraying material, it is common to use condensed sodium phosphate and a calcium compound in combination for high durability. The cause of the remarkable improvement in adhesion and adhesion due to the addition of calcium is that the construction body is hardened using gelation caused by the reaction between the condensed phosphate and the calcium compound, and the calcium phosphate based material having a high melting point is used. Compound such as 3CaO.
P ₂ O ₅ (melting point = 1810 ° C.) or 4CaO · P ₂ O ₅ (melting point =
(1,720 ° C.) at a high temperature to give the construction body a high hot strength.

For example, Japanese Patent Application Laid-Open No. 63-156078 discloses that a dolomite raw material 30 to 70% by weight and a magnesia raw material 70 to 70% by weight are used.
100 parts by weight of a refractory raw material consisting of 30% by weight, 2.5 to 7.0 parts by weight of a condensed sodium phosphate, 0.2 to 1.5 parts by weight of an alkaline salt of a phosphorus-free strong electrolyte, and 0 A spray repair material for a metal smelting furnace containing from 0.3 to 1.5 parts by weight is disclosed.

[0005]

Heretofore, a spraying material using the above-described binder which has fast curing properties and has a melting point as high as possible to be hot has been selected so as to provide adhesion during spraying. However, in the conventional converter operation, a large amount of slag was present in the converter, slag was also attached to the surface of the lining brick, and the sprayed material was bonded via this slag layer. The slag layer has moderate irregularities, facilitates the initial mechanical bonding of the sprayed material, and can maintain strong adhesion by reacting the slag with the refractory material component of the sprayed material at a high temperature. Was something. The damage to the spray material was also due to erosion and erosion affected by the slag basicity and the like. Therefore, a spraying material layer having a melting point as high as possible and stable was preferred.

However, with the recent improvement of processing techniques such as hot metal pretreatment, less slag operation has been carried out in which slag is not brought into the converter as much as possible. Naturally, there was almost no slag in the converter, there was almost no slag adhesion layer on the surface of the lining brick, and the sprayed material had to be directly bonded to the brick surface. The brick surface was smooth and the mechanical adhesion was insufficient, and it was difficult to maintain the adhesive force by reaction with the slag even at high temperatures. Therefore,
The damage of the sprayed material in the operation of the less slag was not caused by erosion or erosion by slag but by peeling from the brick surface.

[0007] That is, conventionally, by increasing the melting point of the bonding system, the bonding strength and the hot strength have been increased to increase the durability of the sprayed construction. In this converter, the adhesive strength cannot be maintained, and only the hot strength becomes a high value. Although the construction body has the strength as an integral body, the phenomenon that the whole construction body is peeled off as an integral body from the bonding surface with the brick due to mechanical or thermal shock due to the small adhesive force has appeared. As a result, the spray repair part that had remained widely up to a certain point of time suddenly disappeared at one time, and the repair work could not proceed as planned.

Accordingly, an object of the present invention is to provide a hot repair spraying material which can maintain the adhesive strength even during hot repair of a converter under operation of a less slag.

[0009]

That is, the hot repair spraying material for a converter for operation of a slagless slag according to the present invention comprises a total of 100 parts by weight of a refractory material of MgO type and a refractory material of MgO-CaO type, and phosphorus as a binder. Acid soda is converted to P ₂ O ₅ in the range of 2.5 to 2.5.
5.5% by weight, 2-6 calcium compounds in terms of CaO
1.5 to 4% by weight of magnesium oxide of 5 μm or less.
% By weight.

[0010]

The hot repair spraying material for a converter according to the present invention is obtained by adding sodium oxide and a calcium compound as a binder to MgO refractory material and MgO-CaO refractory material, and further adding 5 μm or less of magnesium oxide. Thereby, high adhesive strength can be obtained even in a converter under operation of a less slag. That is, by adding a fine magnesium oxide of 5 μm or less, firstly, the brick inside the furnace follows the fine irregularities on the surface to improve the mechanical cracking, and secondly, 2MgO · P ₂ O ₅ (melting point: 1382 ° C) or 3C
By generating a compound having a slightly lower melting point such as aO.3MgO.2P ₂ O ₅ (melting point: 1175 ° C.), a high adhesion is obtained by fusing to a brick surface.

The MgO refractory material used in the present invention is not particularly limited, and any conventional one can be used, such as seawater or natural magnesia clinker, electrofused magnesia clinker and the like.

Next, the MgO-CaO refractory material used in the present invention has a MgO: CaO weight ratio of 85:15 to 3;
Those having a ratio of 0:70 include synthetic magnesia lime clinker, natural dolomite clinker, and the like.

In the present invention, the above-mentioned MgO refractory material and MgO-CaO refractory material are used as refractory raw materials. The weight ratio between the MgO refractory material and the MgO-CaO refractory material is in the range of 90:10 to 30:70.

In the hot repair spraying material of the present invention, sodium phosphate, a calcium compound and magnesium oxide of 5 μm or less are used in combination as a binder for the above-mentioned refractory material. Here, as the sodium phosphate, for example, sodium tetrapolyphosphate, sodium hexametaphosphate, sodium tripolyphosphate, or the like can be used. Adding and blending amount of sodium phosphate is in the range of 2.5 to 5.5 wt% in the refractory material per 100 parts by weight P ₂ O ₅ equivalent amount. If the amount added is less than 2.5% by weight, the initial bonding strength is insufficient, the strength of the construction immediately after spraying is insufficient, and if it exceeds 5.5% by weight, the corrosion resistance may decrease. Moreover, it is not preferable in terms of economy.

Next, examples of the calcium compound used as the binder include calcium hydroxide, calcium carbonate, calcium silicate, calcium aluminate and the like. The addition and blending amount of the calcium compound is in the range of 2 to 6% by weight in terms of CaO per 100 parts by weight of the refractory material. If the amount added is less than 2% by weight, Ca
The production of the O.P ₂ O ₅ -based compound is too small and the hot strength becomes insufficient. If it exceeds 6% by weight, calcium hydroxide,
In the case of calcium carbonate, many pores are generated due to disappearance of H ₂ O and CO ₂ when heated, and calcium silicate,
Calcium aluminate is not preferred because the impurity components of SiO ₂ and Al ₂ O ₃ increase.

Further, in the hot repair spraying material for the converter for the operation of a less slag operation furnace according to the present invention, magnesium oxide of 5 μm or less is used as a binder. If the particle size of the magnesium oxide exceeds 5 μm, the mechanical mechanical stress at the initial stage is small, and the reactivity at the time of heating is inferior, so that it is difficult to produce a target compound.
The addition and blending amount of magnesium oxide of 5 μm or less is in the range of 1.5 to 4% by weight per 100 parts by weight of the refractory material. If the amount is less than 1.5% by weight, the effect of improving the adhesive strength is small, and if it exceeds 4% by weight, the sintering proceeds too much and shrinks, which is not preferred because the adhesive strength is reduced.

[0017] The hot repair spray material for the converter of the present invention having the above-mentioned composition can be used as a dry spray material for hot repair of a converter for the operation of a less slug by a conventional operation.

[0018]

【Example】

Example Spraying materials of the present invention product and the comparative product were prepared at the compounding ratios shown in Table 1 below. Table 1 also shows the results of the hot adhesive strength test and the adhesive strength test after heating of the obtained inventive products 1 to 3 and the comparative product. The hot adhesive strength test was performed by hot-spraying a spraying material of the present invention product and a comparative product on a magnesia-carbonaceous panel at 1000 ° C., and after about 5 minutes, measuring a shearing force for peeling off the adhesive. The hot adhesive strength. In addition, the adhesive strength test after heating was performed by heating the sample sprayed on the magnesia-carbonaceous heating brick together with the brick at 1500 ° C. for 3 hours, measuring the shearing force for peeling the sprayed material after cooling, and bonding after heating. It is the strength.

[0019]

[Table 1]

[0020]

According to the present invention, since the hot repair spray material for the converter for the operation of the reslag slag according to the present invention uses sodium phosphate, a calcium compound and a magnesium oxide of 5 μm or less in combination as the binder, the converter for the reslag operation is free of slag. In the case of hot repair, excellent adhesive strength can be provided.

Continuation of the front page (72) Inventor Toshiyuki Hirose 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-56-104781 (JP, A) JP-A-49-35409 ( JP, A) JP-A-63-156078 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/66 C04B 35/04 F27D 1/00

Claims (1)

(57) [Claims] 1. A total of 100 parts by weight of a MgO refractory material and a MgO-CaO refractory material, 2.5 to 5.5% by weight of sodium phosphate as a binder and a calcium compound as P ₂ O ₅ as a binder. A hot repair spraying material for a less slag operation converter, wherein 1.5 to 4% by weight of magnesium oxide having a CaO equivalent of 2 to 6% by weight and 5 μm or less is added.