JPS598672A - Carbon bonded spray material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon-bonded spray material with excellent adhesion and durability suitable for use in repairing various industrial furnaces such as converters and AOD furnaces.

For example, in a converter, the lining bricks of this furnace are damaged by impact when charging scrap or hot metal, dissolution in slag, wear due to slag flow or molten steel flow, etc., but this damage is used as a lining. The degree of damage varies depending on the location, and the progress progresses unevenly as a whole. Therefore, damaged local areas should be repaired by spraying17, and the damage rate should be balanced and the inner lining should be used effectively. Efforts are being made to reduce the material consumption per unit of production.

The spraying materials used for this repair are conventionally
Refractory raw materials such as magnesia clinker and dolomite clinker to which inorganic binders such as phosphates and silicate are added have been commonly used. However, in recent years, the tapping temperature of the converter has increased due to the widespread use of ladle refining, typified by vacuum degassing treatments such as the KH method and DH method, and the spread of continuous casting to meet the demand for higher quality steel. Temperatures exceeding 1,700°C are no longer rare, and conventional spray materials such as those described above are no longer effective in dealing with such high-temperature operations. This is because in conventional shotgun materials, the bond structure itself reaches its thermal limit, and at high temperatures during use, the ability to bond the refractory aggregate is lost, and at the same time, the connective tissue collapses due to penetration of slag. It is thought that this will lead to this.

Carbon-bonded spray materials have recently been proposed as spray materials that can overcome these drawbacks and cope with high-temperature operation of converters.

Regarding these, for example, Japanese Patent Publication No. 42-27049 discloses a spraying material consisting of a non-acidic fire-resistant aggregate, solid hard pitch of 4 to 100 mesh, a plasticizer, and a water-soluble cold hardening bonding component. JP-A No. 10207 describes a method of hot repair using sprayed material sprinkled with hard pitch on the surface of fireproof aggregate, and JP-A-54-69118 describes a method with a softening point of 20°C.
Carbonaceous resin with residual carbon t80-65 5-80
A spray material is disclosed in which a silicate and/or phosphate is added to a mixture of a refractory aggregate coated with a silica and a refractory aggregate without such a coating.

However, these spray materials had the following problems. In other words, the spraying material described in Japanese Patent Publication No. 42-27049 is added by crushing the solid pitch itself, and the solid pitch may scatter due to its low specific gravity during spraying, or the surface area may be reduced. Due to their large size, they are easy to burn due to the high temperature atmosphere inside the furnace, and the smoke generated at that time worsens the working environment. In the product described in JP-A-54-10207, all of the refractory aggregate is covered with pitch, so this product also generates significant smoke during spraying, and requires the addition of a binder to develop strength at the initial stage of spraying. Therefore, adhesion to vertical walls is particularly poor. The one published in Japanese Patent Application Laid-open No. 54-69118 is
Although the drawbacks of the above two examples are solved to some extent, the carbon source is reduced by the amount of refractory aggregate that is not coated with carbonaceous resin, resulting in poor connective tissue strength and slag resistance.

The present invention has been developed in consideration of the current situation, and it is possible to minimize the combustion of carbon components and the accompanying smoke generation due to the high temperature atmosphere inside the furnace wall or inside the furnace after being sprayed onto the furnace wall, and at the same time to make the carbonaceous resin diffusible. The purpose of the present invention is to provide a carbon-bonded spray material with enhanced carbon-bonding ability by utilizing it under excellent conditions.

The carbon-bonded spray material of the present invention will be described in detail below.

Basically, once carbon-bonded spray materials reach and adhere to the furnace wall surface, they are heated by the furnace wall surface or the high-temperature atmosphere inside the furnace to form a network of carbon bonds. The carbonaceous resin must be able to easily form carbon bonds in a short time by heating, and from this point of view, it is preferable that the carbonaceous resin is uniformly distributed in the spray material. On the other hand, in order to solve the problems of poor mixing due to the carbonaceous resin's difficulty in getting wet with water, as well as the combustion of the carbonaceous resin and the resulting smoke generation, it is necessary to minimize the surface area of the carbonaceous resin and, moreover, It is necessary to suppress the uneven dispersion.

To satisfy these two points, the carbonaceous resin is granulated in some form, its surface area is kept small until it adheres to the furnace wall, and once it reaches the furnace wall, it is granulated by the furnace atmosphere or by heating from the furnace wall. An effective means is to melt and diffuse the granulated carbonaceous resin into the spray material to form carbon bonds.

If carbonaceous resin has a low softening point, it will easily diffuse after adhering to the furnace wall surface and form carbon bonds, but on the other hand, the porosity of the sprayed material will be high due to the high volatile content, and the amount of residual carbon will be low. As a result, carbon bond strength, slag resistance, etc. become insufficient.

On the other hand, if a material with a high softening point is used, the above problem will be solved, but melting and diffusion will not be easy and sufficient carbon bonding will not be obtained.

Therefore, by using two types of carbonaceous resins with different softening points,
The advantages of both, the ease of diffusion of the low softening point carbonaceous resin and the high residual carbon content of the high softening point resin, combine to make the effect of adding the carbonaceous resin even greater. Carbon powder can be roughly divided into crystalline types such as cylindrical graphite, earthy graphite, quiche graphite, and electrode scrap, and amorphous types such as petroleum coke, pitch coke, carbon black, retort carbon, anthracite, and charcoal. However, according to experiments conducted by the present inventors, it has become clear that an amorphous material is more preferable in terms of slag resistance of the sprayed material. This is thought to be because amorphous materials are more active than crystalline materials, making it easier to form carbon bonds.

To give one example of the implementation of the present invention based on the knowledge as described below, the weight ratio is 15 to 35 pitches with a softening point of 100°C or higher, and 15 pitches with a softening point of 200°C or higher.
~85%, 44. A blend consisting of a basic FLL14 pyrotechnic material containing 10 to 30% of amorphous carbon in which particles of AI or below account for 50 units or more, and the remainder consists of particles of 44 units or below that account for 50 units or more, is heated to a temperature higher than the softening point of the above pitch. Carbon-containing refractory particles 5~ obtained by granulating the mixture while heating at a temperature of
By mixing 80 to 959 g of basic refractory raw material and an appropriate amount of binder, a carbon-bonded spray material having desired properties can be obtained.

Next, the behavior of the constituent components of the carbon-bonded spray material of the present invention in each state will be explained in detail.

First, carbon-containing refractory particles include pitch with a softening point of 100°C or lower (hereinafter referred to as low softening point pitch), pitch with a softening point of 200°C or higher (hereinafter referred to as high softening point pitch), amorphous carbon, and base. Among these, the low softening point pitch is softened by the heat of the sprayed furnace walls, etc. [7 Then, it is diffused and the high softening point pitch and amorphous carbon are sprayed. It serves as a carrier for uniform dispersion in the adhered body, and also serves as an element constituting carbon bonds.

The reason why the softening point of the low softening point pitch is limited to 100°C or less is that it is easy to obtain fluidity that allows it to soften and spread throughout the adhered body when heated by the sprayed wall surface or the furnace atmosphere. Sufficient fluidity and diffusion cannot be obtained with a pitch whose softening point exceeds ℃. Further, pitch having a softening point of 100° C. or lower has the advantage that after spraying, fluid diffusion occurs in parallel with volatilization of water from the +1 adherent, and carbon bonds can be formed quickly.

High softening point pitch is necessary to form strong carbon bonds. The softening point was set at 200°C or higher because it has been confirmed that such pitches generally contain a large amount of benzene-insoluble and quinoline-soluble components, that is, β resin, which makes it easy to form strong female bonds. be. Although this high softening point pitch itself has poor fluidity and diffusibility, it is accompanied by the flow and diffusion of the low softening point pitch and disperses throughout the adhered body, forming strong carbon bonds.

Amorphous carbon refers to petroleum coke, pitch coke, various types of carbon black, etc., and is amorphous carbon powder with a volatile content of 5% or less. This is necessary to replenish the amount of carbon required for the spray material, and by supplying carbon from such a carbon source with almost no volatile content, it is possible to reduce the amount of carbonaceous resin required and increase the carbon content. This makes it possible to eliminate causes of deterioration in workability, such as smoke generation during spraying construction, which is caused by the volatile content of the resin, and it is also possible to increase the amount of residual carbon in the carbon-containing refractory particles. Furthermore, it was visually confirmed that this amorphous carbon has the effect of strengthening this bond by being incorporated into the network of carbon bonds formed by carbonizing the pitch.

When crystalline carbon, such as earthy graphite or cylindrical graphite, is used, it is effective in increasing the amount of carbon, but it cannot strengthen the bond. This seems to be due to the waxing and waning of activity based on differences in the chemical properties of the carbon raw materials.For example, amorphous pitch coke obtained by heat-treating pitch has high activity, and the so-called compatibility in association with other pitches is high. Even though it is good, it shows different characteristics when compared to it.

The basic refractory raw material is necessary to increase the specific gravity of the carbon-containing refractory particles.

The particle size of the amorphous carbon and basic refractory raw materials was limited to particles with a particle size of 44 or less having a coefficient of 50 or more, because these particles diffused throughout the adhered body as the pitch softened and spread, resulting in uniform bonding. If the particle size becomes large, there is a concern that, for example, the diffusion of amorphous carbon may be insufficient and uneven bonds may be formed. When the carbon-containing refractory particles are heated and mixed at a temperature higher than the softening point of the carbon and then granulated, the high softening point pitch and amorphous carbon can be easily mixed and granulated due to the flow diffusion of the low softening point pitch when sprayed. It is possible to diffuse uniformly and form a uniform bond over the entire area of the adhered body.

Among conventional spray materials, carbon-containing refractory particles, which are made by coating the surface of a refractory raw material with a carbonaceous resin such as pitch, or a carbonaceous resin and crystalline carbon or amorphous carbon, are However, carbon-containing refractory particles made by coating a refractory raw material with carbonaceous resin, etc., have the disadvantage that the amount of carbon or residual carbon is limited.However, it is difficult to uniformly control the coating layer thickness of each particle. It was difficult and impossible to obtain large quantities of carbon-containing refractory particles of homogeneous composition.

On the other hand, since the carbonaceous refractory particles in the present invention are a mixture of refractory raw material fine powder and carbonaceous resin, the carbonaceous resin is homogeneously distributed and contained in the particles in large quantities. Therefore, the amount of residual carbon is also extremely high.

Next, the optimum range of each material constituting the carbon-containing refractory particles will be explained.

The reason why the amount of low softening point pitch added was 15 to 85 pitch was 1.
If it is less than 5 cm, it will not be possible to obtain the activity to make the composition uniform during heating and mixing, and after spraying, there will be insufficient fluidity to diffuse the high softening point pitch and amorphous carbon throughout the deposited body. Moreover, if it exceeds 85%, the porosity of the sprayed material will increase due to an increase in volatile content.

The reason why the high softening point resin was set at 15 to 85 is that if it is less than 15, the formation of carbon bonds will not be sufficient, and in order to obtain the desired carbon bonds, a large amount of carbon-containing particles must be added to the spray material. This is because high hot strength cannot be obtained, and on the other hand, using a large amount of carbon-containing particles is undesirable as it will cause a reduction in workability such as smoke generation as described above.
Moreover, if it exceeds 85%, fluidity due to heating and melting tends to decrease due to the relationship with other components.

The reason why the particle size of amorphous carbon is limited to 44) where particles of 1 or less occupy 50 squares or more is to facilitate diffusion by softening and flow of pitch. And the mixing ratio is 1
The reason for setting the range from 5 to 35 is that if it is less than 15 inches, the effect of adding the above-mentioned amorphous carbon will be small, and if it exceeds 35 inches, the volume ratio of the carbon-containing refractory particles will become extremely large, reducing the specific gravity of the carbon-containing refractory particles. let Furthermore, there is a drawback that carbon bonds formed by pitch carbonization are inhibited.

The reason for using basic refractory raw material fine particles with a particle size of 44μ or less particles accounting for 50μ or more is that as the particle size increases,
This is because a separation phenomenon tends to occur during mixing due to the difference in specific gravity between the softened and liquefied pitch or amorphous carbon, and this makes it difficult to obtain carbon-containing refractory particles with a uniform composition. Furthermore, in order to increase the carbon content of the carbon-containing refractory particles as described above, the basic refractory raw material must be in the form of fine particles as described above.

Granulation after heating and mixing low softening point pitch, high softening point pitch, amorphous, carbon and basic refractory raw materials can be carried out by well-known means,
For example, carbon-containing refractory particles can be obtained by a dropping method, a gasification method, a swirling flow method, or the like.

The proportion of carbon-containing refractory particles in the total sprayed material is 5 to 20.
If it is less than 5%, the residual carbon content of the sprayed material as a whole will be low and sufficient hot strength and corrosion resistance cannot be obtained, and if it exceeds 20%, there will be a large amount of volatile content. This is because K forms a porous structure, resulting in a decrease in corrosion resistance, and K increases smoke generation during spray repair, resulting in a decrease in workability.

The basic refractory raw materials mixed into the carbon-containing refractory particles and the basic refractory raw materials separately mixed into the carbon-containing refractory particles include seawater magnesia clinker-1 synthetic dolomite clinker, magnesia alumina spinel clinker,
One or more types of magnesia chromium spinel clinker or chromite can be used. in this case,
In order to make the effect of the basic refractory raw material even more remarkable, the sonochemical composition should be changed to (MgO+CaO) or (MgO+A
1 gOa) is preferably 96 inches or more.

This is to prevent an oxidation-reduction reaction that occurs at high temperatures between the carbon in the spray material and the 7 lux component in the basic refractory raw material such as Sing or 20 g of Fe.

The applied spray material is heated after adhering to the furnace wall, and carbon bonds are formed by flow diffusion of carbon-containing refractory particles, but at high temperatures, the carbon forming the bonds and the flux component S*OH or FezOB An oxidation-reduction reaction occurs between the two, and carbon bonds are destroyed as shown in the following reaction formula.

S1'02→-2C→ss+2co ・・・・・・・・・
・・・・・・・・・・・・(1)6 F820B+ 2C
→4FeBO4+ 2GO-・-・-(2) The reaction of formula (1) is at 1500℃, and the reaction of formula (2) is 800℃.
If these flux components are present in multiple needles, the bonds will be destroyed by oxidation and loss of carbon at high temperatures during use.

On the other hand, the redox reaction between M g 01 CaO 1 A 12 θm and carbon occurs only at temperatures around 1800°C;
Olp a OlA I20B has little influence on carbon bonds. Therefore, among the basic refractory raw materials, magnesia chromium spinel clinker, chromite, etc., which have a large flux component, are not preferable.

The binder is added to keep the spraying material attached to and held on the furnace wall surface during the time after the carbon-containing refractory particles flow and diffuse until a bond is formed. One or more phosphates such as potassium phosphate or silicates of alkali metals such as No. 1 sodium silicate, No. 8 sodium silicate, potassium silicate, etc. are selected according to the purpose, and an appropriate amount is applied, for example, as an external layer. So 2~
Add about 10 g. Furthermore, a carbo thickener may be added if necessary.

The carbon-bonded spray material of the present invention obtained by adjusting as described above not only emits extremely little smoke during spraying, but also has good adhesion and carbon bond-forming ability. Excellent results were obtained in terms of workability and durability, including environmental and safety issues, and it is suitable for repairing point furnaces, such as converters, which have particularly severe operating conditions.

Next, various examples according to the gist of the present invention will be illustrated in comparison with comparative examples.

The characteristic values of the carbonaceous resin and carbon used on each side are shown in Table 1.
In addition, the chemical compositions of the basic refractory raw materials used on each side are shown in Table 2, and Table 3 shows the blending ratio of carbon-containing refractory particles mixed with ξ and the amount of residual carbon in the same particles. In addition, Table 4 (consisting of Part 1 and Part 2) shows the blending ratios and characteristic values of Examples of the present invention and Comparative Examples.

From these results, the following physical properties or characteristics based on them were verified, and the effects exhibited were selected as appropriate.

The method for granulating the carbon-containing refractory particles shown in Table 8 was as follows. That is, the symbols A-M and Q indicate the ingredients listed in the table, heated and mixed at 250 to 850°C, placed in a container with a number of small holes with a diameter of 9 mm in the bottom, and the mixture was poured into the small holes. It was granulated by dropping it into a water tank and solidifying it by cooling. Symbols NP are the basic refractory raw materials, carbon powder, and high softening point pitch among the ingredients in the table, and after adding the low softening point pitch heated and melted at 150 ° C.
Zudo ;] 1chi,
The symbols A-II were used in the examples of the present invention, and the amount of residual carbon was high. Therefore, 711 in Table 4, which is the spray material of the embodiment of the present invention containing these
i1-9) have high hot strength and excellent workability. Incidentally, the particles with codes F and G in Table 3 have a high residual carbon content, and the spray materials No. 7.8 and No. 23 in Table 4 that contain these particles have excellent workability, but the relationship with the refractory raw materials used is It tends to be somewhat inferior in hot properties.

The carbon-containing refractory particles of the comparative example with code 1-L in Table 3 are as follows:
The spray materials of 71il O to 13 in Table 4, which do not contain carbon powder and are blended with this grain, have poor hot strength.

The carbon-containing refractory particles with codes M and N used in the comparative examples in Table 8 were carbon-containing refractory particles to which crystalline carbon was added as carbon powder, and the carbon-containing refractory particles shown in Table 4 were mixed with the carbon-containing refractory particles shown in Table 4.
Although the sprayed material No. 5 has excellent workability, it is inferior to the examples of the present invention in terms of hot strength, and this is thought to be because amorphous carbon is more compatible with pitch than crystalline carbon.

The code 0 used in the comparative example in Table 8. Since the refractory raw material particle size of P is large, the peripheral surface of the refractory raw material is coated with carbon powder or pitch, so the amount of residual carbon is small.

The spray material A16 shown in Table 4 containing these particles has a low carbon content and good workability, but low hot strength. On the other hand, No. 17 and No. 18 in Table 4 have a high carbon content and excellent hot strength, but because a large amount of carbon-containing refractory particles are added, a lot of yc smoke is generated during spraying, and workability is reduced.

The spray material A19 in Table 4, in which the carbon-containing refractory particles of code q in Table 3 are blended with a small amount of high softening point pitch added, is slightly inferior in workability and hot properties. This seems to be due to the fact that the low softening point pitch is inferior to the high softening point pitch in its ability to form carbon bonds, in conjunction with the addition of a large amount of the low softening point pitch with a high volatile content.

Spraying material/Ffl in Table 4 that does not contain refractory raw materials and is blended with particles of the code technique in Table 8, which consists only of pitch and carbon powder.
i20.21 has poor workability. This is because the particles have a low specific gravity because they do not contain refractory raw materials, and are easily scattered and burned when sprayed.

In addition, A22.2B in Table 4 is a spray material containing carbon-containing refractory particles used in the examples of the present invention.
The spray material No. 2 has poor hot properties because the amount of these particles is small, and the spray material No. 28 has an excessive amount of these particles, resulting in poor workability.

As described above, it has been confirmed that the sprayed materials of the examples of the present invention exhibit an outstanding function in generating carbon bonds.If the gist of the present invention is followed, the technical idea is It goes without saying that the present invention is not limited to the examples, and any applications, diversions, or modifications derived therefrom are included within the technical scope of the present invention.

(19) Table 1 Carbonaceous iris (characteristic values of fat P and carbon 4A2 table
Basic mastication 1fi (PI-Chemistry IJ''4 min (wt%)
(20) Procedural amendment (voluntary) September 1980/- Name of the invention Person making the amendment to carbon-bonded sprayed material (Relationship with '1) Patent application agent and one other person 1:1 attached Showa year Subject of correction: Specification, detailed description of the invention.

Contents of the amendment Attached sheet ■ Description, page 3, line 17, "refractory bone"
Correct it to "fireproof aggregate".

■ In the specification, page 7, line 2 to line 8, "the present invention..." is replaced with "the present invention..."
I will correct it.

11] Specification, page 9, line 20, “Dependency of activity”
I am correcting the statement as "difference in activity".

■ Specification, page M11, line 1s, where it says "active",
Corrected as "liquidity".

■ Book #I, page 12, lines 6 to 7, “
Correct the sentence ``I don't have to add it...'' to ``If I have to add it, it will last a long time.''

(1)

Claims (1)

[Claims] 1. Pitch 15 to 8 with a softening point of 100°C or less in terms of weight ratio
5chi, pitch 15-85% and 4 with a softening point of 200℃ or higher
Amorphous carbon 10 to 8 in which 50 or more particles of jA or less occupy
After heating and mixing a basic refractory raw material containing 10% of pitch and the remainder being 50% or more of particles of 44 or less size, this is granulated. A carbon-bonded spray material prepared by mixing 5 to 20 units of carbon-containing refractory particles obtained in this way, 80 to 95 units of basic refractory raw material, and an appropriate amount of a binder. 2. The basic refractory raw material according to claim 1, the chemical composition of which is MgO+CaO or MgO+A1.
A carbon-bonded spray material characterized in that gOn exceeds 96 gOn by weight.