JPH10139557A - Flame thermal spraying material for repairing kiln and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame thermal spraying material for repairing a kiln which allows the effective utilization of resources without classifying and removing fine particles and a process for producing the same. SOLUTION: This flame thermal spraying material for repairing the kiln consists of powder particles of a thermal spraying raw material which contains inorg matter capable of contg. water of crystallization at 0.5 to 4.5wt.% in outer percentage and is bonded by the inorg. matter. The content of these grains of <=45μm in grain size is <25wt.%. The inorg. matter to be added is the crystal water salt of sodium hydrogenphosphate, the crystal water salt of sodium phosphate and the crystal water salt of sodium silicate. At the time of producing the flame thermal spraying material for the kiln, the thermal spraying raw material and the inorg. matter contg. the water of crystallization are first mixed at room temp. and are then mixed under heating to the tap. above the tap. at which the inorg. matter dehydrates the water of crystallization. Further, the mixture is dried to evaporate the dehydrated moisture, by which the thermal spraying material is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame spray material for repairing a kiln used in a steel manufacturing process and a method for manufacturing the same.

[0002]

2. Description of the Related Art In order to extend the service life of a kiln used for metal refining, refractory repair is performed hot, and a flame spraying method is widely used as a means for repairing refractories.
As a component of the refractory powder used in the thermal spraying material, in a steelmaking converter used in a steelmaking process, MgO-slag and MgO-CaO-slag are used. For example, Japanese Patent Publication No. 56-23950, Japanese Patent Publication Sho 6
Japanese Patent Publication No. 0-53273 discloses a composition obtained by adding converter slag to magnesia clinker, and Japanese Patent Publication No. 2-40024 discloses a composition comprising magnesia clinker, lime clinker and converter slag.

[0003] In addition, Al ₂ O ₃
-MgO _{quality, Al 2 O 3 -MgO-Cr} 2 O 3 quality is used. For example, Japanese Patent Publication No. 60-35311 discloses a composition comprising an alumina raw material, a chromium raw material, and an alumina-magnesia spinel raw material.

[0004] Refractory powders used for thermal spraying materials are required to have excellent meltability and powder fluidity. That is, if a material having a large number of fine particles is used so as to be easily melted, there is a problem that the fluidity is impaired and pulsation occurs at the time of discharging the powder or the powder is clogged with a transport pipe. When a large material is used, there is a problem that the particles are attached without being completely melted or are scattered as dust without being attached. Thus, as the particle size of the thermal spray material, for example, Japanese Patent Application Laid-Open No. 55-21539 discloses that the total thermal spray material particle size is 500 μm or less, and the ratio of particles having a particle size of 10 μm or less to 20% or less. I have. Also,
Japanese Patent Publication No. 61-10418 discloses an average particle size of 10 μm.
It is disclosed that the following refractory material particles are combined with an organic binder and granulated into secondary particles of 30 to 500 μm for use.

[0005]

However, the above-mentioned Japanese Patent Application Laid-Open No. 55-21 is used for removing the fine particles by classification and using them as a material for thermal spraying.
In the prior art disclosed in Japanese Patent No. 539 and the like, since the removed fine particles are rarely reused, the raw material yield is directly reduced, and the material cost is a problem.

On the other hand, granulation is considered as a method of using fine particles as a thermal spraying material. As the granulation method, for example, an organic binder disclosed in Japanese Patent Publication No. 61-10418 or the like is added as an aqueous solution and dried. A method (called a spray drying method) is often used. However, such a method of adding an aqueous solution requires the use of a relatively large amount of water, and increases the cost in a subsequent drying step. It is not preferable as a processing method. The water used in the spray drying method or the like is mainly water necessary for penetrating the binder, and the granulated material hardly contains water. Is difficult.

Further, MgO-slag, MgO-CaO
-Since the slag spray material contains a digestible raw material, it is not preferable to use a large amount of water as in the above prior art. Furthermore, if the residual moisture control is not sufficiently performed in the drying step, there is a concern that the fluidity is rather deteriorated.

Therefore, the present invention improves the fluidity by granulating fine particles without using a large amount of water,
It is an object of the present invention to provide a flame sprayed material for furnace repair which can be used without classifying and removing fine particles, and a method for producing the same.

[0009]

The gist of the present invention for solving the above problems is as follows.

(1) A powder particle size of 500, which is used for repairing a kiln for a steelmaking process and is made of refractory powder as a raw material.
In the flame sprayed material having a particle size of not more than μm, the fine particles having a particle size of not more than 45 μm in the refractory powder raw material are mutually interspersed and / or 0.5 to 4.5 in a round manner with the refractory powder having a particle size of more than 45 μm.
Including powders having a particle size of more than 45 μm which are combined and granulated with a weight% (in a dehydrated state) of an inorganic substance, wherein the proportion of powder having a particle size of 45 μm or less is less than 25% by weight. Flame spray material for kiln repair,

(2) The flame spray material for repairing a kiln according to the above (1), wherein the inorganic substance is sodium hydrogen phosphate, sodium phosphate or sodium silicate.

(3) A powder particle size of 500, which is made of refractory powder and used for repairing a kiln for a steel manufacturing process.
In a method for producing a flame-sprayed material having a diameter of 0.5 μm or less, a dehydrated state of an inorganic material equivalent to 0.5 to 4.5% by weight of an outer shell, and a crystal water salt containing 0.5 to 1.5% by weight of an outer shell of crystallization water Mixing at room temperature until the existence probabilities between the powders of the refractory powder raw materials are substantially equal to each other, and then heating the resulting mixture to a temperature not lower than the temperature at which the water of crystallization of the inorganic substance is dehydrated. By continuing the mixing, the inorganic substance itself is dissolved in the water released from the crystal salt, and the resulting solution is mixed between fine powder having a particle size of 45 μm or less in the refractory powder raw material and / or Alternatively, the fine powder and the refractory powder having a particle size of more than 45 μm are infiltrated between each other, and then further heated and mixed to evaporate the water content of the solution and to dry the mixture. The refractory powder raw material having a diameter of 45 μm or less is Method for producing kiln repair flame spraying material ratio of the powder particles is less than 25% by weight, characterized in that to couple-granulation, the particle diameter is 45μm or less through,

(4) The method for producing a flame spray material for repairing a kiln according to the above (3), wherein the inorganic substance is sodium hydrogen phosphate, sodium phosphate or sodium silicate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention improves the flowability of a flame spray material for repairing a kiln having many fine particles by adding an inorganic substance capable of containing water of crystallization.
The aim is to make effective use of the fine particles.

The inorganic substance used in the present invention is a solid containing water of crystallization at room temperature at the time of addition. However, since the manufacturing method involves heat treatment, the inorganic material in the thermal sprayed material manufactured according to the present invention hardly contains water of crystallization.

The amount of the inorganic substance to be added is determined by dehydrating the outer material.
If more than 5% by weight is added, the characteristics of the thermal spraying body are reduced by the inorganic substance. Therefore, the upper limit of the addition amount is not more than 4.5% by weight in a dehydrated state. On the other hand, if the addition amount is less than 0.5% by weight in the dehydrated state, the bonding and granulating effects of the refractory powder are insufficient, and the particle size is 45 μm.
m or less cannot be less than 25% by weight, so the lower limit of the amount added is 0.5
Weight% or more. In the present invention, the addition amount of the inorganic substance is expressed as “equivalent to XX% by weight in a dehydrated state” because the amount of water of crystallization that does not ultimately remain in the flame spray material for kiln repair is separately specified. This is because it was determined to be necessary.

The amount of water of crystallization of the inorganic water salt of crystallization needs to be 0.5 to 1.5% by weight on the outside. This is 0.5% by weight
If it is less than 1, the inorganic substance cannot be uniformly penetrated into the refractory powder raw material. On the other hand, if the amount of water of crystallization exceeds 1.5% by weight and becomes excessive, efficient drying becomes difficult.

In the present invention, a water crystal salt of sodium hydrogen phosphate, a water crystal salt of sodium phosphate, and a water crystal salt of sodium silicate are used as the inorganic substance which can contain water of crystallization. The crystal hydrate is a solid containing water of crystallization at room temperature, is easily dehydrated by heating, and has a granulating effect because it is a substance used as a binder for refractories, and is used as the inorganic substance of the present invention. it can. The crystal hydrate includes monohydrate, dihydrate, and dodecahydrate, and may be appropriately selected as long as the amount of water to be dehydrated and the amount of inorganic matter in a dehydrated state are within the above ranges. .

In the present invention, the particle diameter of the inorganic substance to be added is not specified because the water of crystallization is dehydrated during the production process, and the water is degraded. However, it is necessary that the dehydrated water uniformly penetrates into the refractory powder raw material. It is preferable that the refractory powder raw material and the inorganic substance are mixed as finely as possible and have a maximum particle size equal to or smaller than the maximum particle size of the refractory powder raw material.

In the production of the flame sprayed material for furnace repair according to the present invention, first, a refractory powder raw material and a solid inorganic material containing water of crystallization are mixed at room temperature, and the inorganic material is uniformly mixed in the refractory powder raw material. Disperse in. That is, the amount of dehydrated water from the inorganic crystal water salt is as small as 0.5 to 1.5% by weight, as described above. Before the dehydration, the inorganic material containing water of crystallization and the refractory powder raw material are sufficiently mixed before dehydration. Since the hydrated hydrate used in the present invention is in a solid state at room temperature, the inorganic material and the refractory powder raw material are easily mixed, and the crystallization water to be dehydrated in the subsequent step is advantageously distributed among the refractory powders. Can be. The temperature at the time of mixing may be lower than the temperature at which the water of crystallization of the crystal water salt is dehydrated, but the mixing is performed at room temperature because heating and cooling means are not required.

Subsequently, the obtained mixture is continuously mixed while being heated to a temperature at which the water of crystallization of the inorganic substance is dehydrated or more, so that the water of crystallization is released from the water salt of crystallization, and the inorganic substance itself is dissolved in the released water. Let it. As described above, a sufficient amount of the inorganic substance solution can be generated with the amount of dehydrated water from the crystal hydrate of the inorganic substance (0.5 to 1.5% by weight). As described above, since this solution is formed from the inorganic crystal water salt distributed with the probability of being substantially equal among the powders of the refractory powder raw material, one solution is formed between the refractory powders. Can be infiltrated in any way.

Thereafter, by further heating and mixing to evaporate and dry the water, fine particles of the refractory powder raw material can be granulated by the binder effect of the inorganic substance.

The refractory powder raw material used in the present invention is:
There is no particular limitation, and the present invention is applicable to all refractory compositions used for thermal spray materials.

[0024]

EXAMPLES Examples of the present invention and comparative examples are shown in Table 1.
No. Nos. 1 to 4 are examples of the present invention. Nos. 5 to 7 are comparative examples out of the scope of the present invention. 8 is a conventional material. As shown in the table, the refractory powder raw materials used in Examples 1 to 4 and Comparative Examples 5 to 7 are materials having a content of fine particles of 45 μm or less larger than that of Comparative Example 8. To each refractory powder raw material, a predetermined amount of an inorganic substance shown in Table 1 was added, and the treatment was performed under the indicated conditions.

The fluidity of the refractory powder raw material was evaluated by the degree of compression. That is, the bulk specific gravity when the powder is naturally filled and 1
Compressibility = 100 × (1-bulk specific gravity / solidified specific gravity) was calculated from the compacted specific gravity when the powder was filled by performing tapping 80 times. It can be evaluated that the smaller the numerical value, the better the fluidity. As for the properties of the sprayed material (material after treatment), the fluidity was qualitatively evaluated from the ejection and pulsation from the sprayed burner, and the corrosion resistance was evaluated from the amount of erosion caused by spraying molten slag to the construction body. . The smaller the erosion index, the better the corrosion resistance.

The refractory powder raw materials used in Examples 1 to 4 and Comparative Examples 5 to 7 have a low degree of fluidity due to their high compressibility. As a result of an experiment, it was necessary to set the compression degree to at least less than 25 in order to be able to use without thermal pulsation during thermal spraying.

In Example 1, 5% by weight of sodium dihydrogen phosphate dihydrate (NaH ₂ PO ₄ .2H ₂ O) was added and mixed, followed by stirring and mixing while heating to 95 ° C. The water content is 1.2% by weight. As a result, 45
The content of fine particles having a particle size of μm or less was reduced to 9%, the fluidity was improved, and the compression degree was 17, which was equivalent to that of the conventional material of Comparative Example 8. There was no pulsation at the time of thermal spraying, and the erosion index was equivalent to that of the conventional material of Comparative Example 8.

In Example 2, disodium hydrogen phosphate dodecahydrate (Na ₂ HPO ₄ .12H ₂ O) was used as an inorganic substance to be added.
Was used. In order to make the water content equal to that of Example 1, 2% by weight of an inorganic substance was added. As a result of stirring and mixing while heating to 95 ° C., the content of fine particles having a particle size of 45 μm or less was 17%, and the degree of compression was 20. The fluidity was slightly inferior to that of Example 1, but the spraying properties were comparable to those of the conventional material of Comparative Example 8. Met.

In Example 3, sodium metasilicate (Na
₂ SiO ₃ .nH ₂ O) was added at 2% by weight, and heated and mixed at 350 ° C. Although the granulation effect was not as great as that of sodium hydrogen phosphate, the spraying properties were equivalent to those of the conventional material of Comparative Example 8.

Example 4 is an example in which sodium phosphate dodecahydrate (Na ₃ PO ₄ .12H ₂ O) was added. 9
When stirring and mixing while heating to 5 ° C., 45 μm
The following fines content was 19% and the degree of compression was 21.
At the time of thermal spraying, there was no pulsation and the corrosion resistance was equivalent to that of the conventional material of Comparative Example 8.

In Comparative Example 5, when the addition amount of sodium dihydrogen phosphate / dihydrate was set to 10% by weight, the amount of added water increased and the compressibility was slightly lowered, but thermal spraying could be performed without pulsation. . However, corrosion resistance was poor due to the large amount of inorganic substances.

In Comparative Example 6, although an anhydrous salt of sodium dihydrogen phosphate was used as the inorganic substance to be added, the inorganic substance could not be permeated between the particles of the refractory powder raw material due to dehydrated water, and granulation could not be performed. . Therefore, pulsation occurred at the time of thermal spraying, and the corrosion resistance could not be evaluated due to poor construction.

In Comparative Example 7, the same inorganic substances were added as in Example 1, but no heating and mixing were performed. Therefore, since only solid inorganic substances were added without dehydration, the thermal spraying properties were not favorable as in Comparative Example 6.

[0034]

[Table 1]

Notes to Table 1: * Na ₂ SiO ₃ .nH ₂ O: Although a hydrated crystal having a specific n value cannot be obtained, those having an n value of about 10 are industrially manufactured. ** Amount of inorganic substance added: indicates the amount of hydrated crystal (Comparative Example 6)
except for). The amount in the dehydrated state is the amount obtained by subtracting the amount of water in the table.

[0036]

As described in detail above, according to the present invention,
By granulating the fine particles without using a large amount of water, not only can the fluidity of the flame sprayed material for furnace repair be improved, but also the resources can be effectively used without classifying and removing the fine particles of the refractory of the sprayed material. Therefore, it can be said that the present invention is an industrially valuable invention because it is possible to provide a furnace-spraying flame-spray material for repairing a kiln and a method for producing the same.

Claims (4)

[Claims] 1. A flame sprayed material having a powder particle size of 500 μm or less, which is used for repairing a kiln for a steel manufacturing process and has a powder particle size of 500 μm or less, wherein a particle size of the refractory powder material is 45 μm. The following fines are mutually and / or have a particle size of 4
0.5 to 4.5% by weight of refractory powder over 5 μm
(Dehydrated) inorganic particles combined and granulated to a particle size of 45μ
A flame spray material for kiln repair, comprising a powder having a particle size of more than m and having a particle size of 45 μm or less in a proportion of less than 25% by weight. 2. The flame spray material for repairing a kiln according to claim 1, wherein the inorganic substance is sodium hydrogen phosphate, sodium phosphate or sodium silicate. 3. A method for producing a flame sprayed material having a powder particle size of 500 μm or less, using a refractory powder as a raw material, which is used for repairing a kiln for a steelmaking process. 4.5% by weight of inorganic material, 0.5
A hydrated water salt containing １．５1.5% by weight of water of crystallization is mixed at room temperature until the existence probabilities between the powders of the refractory powder material are substantially equal, and then the resulting mixture is obtained. By continuously mixing while heating to a temperature at which the water of crystallization of the inorganic substance is dehydrated, the inorganic substance itself is dissolved in the water released from the crystal hydrate, and the resulting solution is used as a raw material for the refractory powder raw material. Between the fine powder having a particle size of 45 μm or less,
And / or infiltrating between the fine powder and the refractory powder having a particle size of more than 45 μm, and then further heating and mixing to evaporate the water content of the solution and to dry the mixture, The refractory powder raw material having a particle size of 45 μm or less is bonded and granulated via the inorganic material, and the proportion of powder particles having a particle size of 45 μm or less is 25%.
A method for producing a flame spray material for repairing a kiln, which is less than the weight percentage. 4. The method according to claim 3, wherein the inorganic substance is sodium hydrogen phosphate, sodium phosphate, or sodium silicate.