JP2002284583A - Method for spraying refractory and spray material used for its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for spraying a refractory that prevents peel damage of a spray application body. SOLUTION: In the refractory spray method that sprays a spray material, which is adjusted as sludge-like in advance by adding application moisture, by adding a quick setting admixture into a nozzle or a delivery pipe under pressure, a refractory aggregate composition used for the refractory spray method comprises a volatilized silica of 6 to 18 mass %, a calcined alumina of 1 to 7 mass %, a sintered alumina fine powder and/or an electromelted alumina fine powder of 10 to 30 mass % having a particle size of 75 μm or smaller and the remains composed of a refractory aggregate other than above. Further, in above refractory aggregate, the effect becomes bigger when a mass ratio of calcined alumina/volatilized silica is in the range of 1 to 0.1 and calcined alumina + (sintered alumina fine powder and/or electromelted alumina fine powder)}/volatilized silica is in the range of 2 to 5. Furthermore, it is preferable to add the quick setting admixture into the nozzle or the delivery pipe under pressure on the condition of mixing with the refractory fine powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory spraying method and a spray material used for the method.

2. Description of the Related Art A refractory is sprayed as a lining for a high-temperature furnace, a molten metal container, a molten metal processing apparatus or the like or as a means for repairing the lining. As one of the spraying methods, there is a method of spraying a spraying material, which has been adjusted into a slurry by previously adding construction moisture, by adding a quick-setting agent in a nozzle. For example, JP-A-10-182246 and JP-A-10-95678
And the like (the coagulant described in the content of the publication is synonymous with the quick-setting agent). In this method, since the working water is added to the spray material in advance, dust generation is smaller than in a dry spray method in which the working water is added in a nozzle, for example, and the working environment during the working is excellent. Further, since the quick-setting agent is added in the nozzle, there is no problem such as hardening during storage of the spray material and nozzle blockage due to hardening of the spray material in the pressure pipe.

The spraying material used in the above-mentioned spraying method is a general material obtained by combining volatile silica and calcined alumina with a main aggregate. Properties required for the spray material include corrosion resistance, adhesion, and peel resistance. Both volatile silica and calcined alumina are ultra-fine powders. By imparting the fluidity of the sprayed material, it acts as a so-called water reducing agent to reduce the construction moisture of the sprayed material. Has the effect of improving In addition, the volatile silica reacts with the quick setting agent to improve the adhesion of the spray material. However, volatile silica and calcined alumina have a high reaction rate, and a spraying material containing the same is liable to cause peeling damage due to sintering shrinkage and crack generation accompanying oversintering. No matter how excellent the spraying material is in corrosion resistance and adhesion, a material having poor peel resistance cannot exert its effect. The present invention relates to a refractory spraying method in which a spray material adjusted in a slurry form is sprayed by adding a quick-setting agent in a nozzle, and in which a spray-resistant material that determines the life of the spray material without impairing its workability. The purpose is to improve the sexuality.

A feature of the present invention is that a spraying material, which has been prepared in advance into a slurry by adding working water, is sprayed by adding a quick-setting agent in a nozzle or a pressure feed pipe. In the refractory spraying method to be applied, the composition of the refractory aggregate of the sprayed material is 6 to 13% by mass of volatile silica,
7 mass%, sintered alumina fine powder having a particle size of 75 m or less and / or
Alternatively, it is a refractory spraying method using 10 to 30% by mass of the fused alumina fine powder and the rest being other refractory aggregates, and a spraying material used therefor. In order to improve the peeling resistance of the sprayed material, it is conceivable to reduce the amount of either volatile silica or calcined alumina to suppress sintering shrinkage. Therefore, in the prior art, the volatile silica is reduced. Volatile silica is Si
This is because an O ₂ -based low melt is easily generated, and when the amount used is large, the corrosion resistance of the sprayed material is reduced. The spraying material used in the present invention reduces the amount of calcined alumina, contrary to the conventional viewpoint, and on the other hand, fine powder of sintered alumina and / or fused alumina having a particle size of 75 μm or less (hereinafter, alumina fine powder) ) Is combined with 10 to 30% by mass. Volatile silica is highly reactive and reacts with alumina materials to form mullite (3A).
l ₂ O ₃ · SiO ₂ ). The volume expansion accompanying the formation of mullite suppresses sintering shrinkage due to the use of volatile silica and calcined alumina. Further, the generation of mullite reduces the vitrification of the sprayed material structure, and suppresses the occurrence of cracks. In the present invention, a sufficient amount of alumina fine powder is present around the volatile silica by combining 10 to 30% by mass of alumina fine powder having a particle size of 75 μm or less. This promotes the formation of mullite, which acts to suppress sintering shrinkage. Alumina fine powder, which is sintered alumina or electrofused alumina, is chemically more stable than calcined alumina, and may cause over-sintering that causes sintering shrinkage even when used in a large amount as in the present invention. Nor. In the present invention, the effect of anti-spraying property of the spray material is as follows: the spray material composition has a mass ratio of calcined alumina / volatile silica of 1 to 0.1, [calcined alumina + (sintered alumina fine powder and / or fused alumina fine powder). )] /
It is more effective when the volatile silica is 2 to 5. Spraying by adding a quick-setting agent in a nozzle or a pressure feed pipe has a problem that the spraying material is sprayed without being sufficiently mixed with the quick-setting agent. The spraying material used in the present invention becomes viscous in a muddy state after the addition of construction water due to the large amount of volatile silica used, and it is difficult for the quick-setting agent to be mixed.
Insufficient mixing of the quick-setting agent results in poor adhesion. In addition, the unevenness of the structure causes a reduction in corrosion resistance. In the present invention, when the addition of the quick-setting agent is performed by mixing with the refractory fine powder, the refractory fine powder is divided into the spray material in the nozzle or the pressure feed pipe, and the mixing of the quick-setting agent with the spray material becomes uniform. Further, the structure of the spray material itself is coarse because the calcined alumina is reduced and the amount of the alumina fine powder used is increased, and the spray material is easily mixed with the quick setting agent.

BEST MODE FOR CARRYING OUT THE INVENTION In the spraying material used in the present invention, volatile silica used as a part of a refractory aggregate is, for example, an average particle size of 1 μm or less, which is obtained as a by-product in the production of silicon or silicon alloy. , Specific surface area is 5-4
It is ultrafine silica powder of about 0 m ² / g, and is highly reactive because it is amorphous. It is commercially available under trade names such as silica flower and micro silica. Purity is SiO ₂
It is 90% by mass or more in conversion. The volatile silica has an effect as a water reducing agent of the spraying material and an improvement in adhesion, and further has an effect of suppressing sintering shrinkage by forming mullite by reacting with peripheral alumina fine powder. If the proportion in the refractory aggregate is less than 6% by mass, the above effect cannot be exhibited. If it exceeds 13% by mass, the amount of the ultrafine powder in the composition of the sprayed material becomes excessive, resulting in sintering shrinkage and reduction in corrosion resistance. More preferably, it is 6 to 10% by mass. On the other hand, calcined alumina is obtained by firing aluminum hydroxide obtained by the Bayer method in a low temperature range of about 1000 to 1300 ° C. α-Al ₂ O ₃ as a main component. The refractory is used by pulverizing it, but since it is not strongly fired, it is naturally obtained as an ultrafine powder having an average particle diameter of 10 μm or less by pulverization. The calcined alumina acts on the water reducing agent of the spray material and the close packing of the matrix portion, and has an effect of improving workability. The purity is preferably 98% by mass or more in terms of Al ₂ O ₃ . If the proportion in the refractory aggregate is less than 1% by mass, the effect of improving workability is poor.
If the content exceeds 7% by mass, over-sintering of the sprayed material causes sintering shrinkage and cracks which cause peeling damage. More preferably, it is 1 to 5% by mass. Alumina fine powder having a particle size of 75 μm or less reacts with volatile silica, and suppresses sintering shrinkage of the sprayed material by volume expansion accompanying mullite generation. Sintered alumina and / or electrofused alumina whose particle size has been adjusted by pulverization and having a purity of 95% by mass or more in terms of Al ₂ O ₃ are used. If the proportion of the alumina fine powder having a particle size of 75 μm or less in the refractory aggregate is less than 10% by mass, mullite is insufficiently generated, and the effect of peel resistance cannot be obtained.
If it exceeds 30% by mass, the fluidity of the spray material will decrease,
The construction water must be increased, and the spray construction body becomes porous, resulting in poor corrosion resistance. The unit of the alumina fine powder having a particle diameter of 75 μm or less is based on JIS sieve opening. If the particle diameter is 75 μm or less, for example, 45 μm or less,
The particle size may be 2 μm or less. In addition, in terms of the effects of adhesion and peeling resistance, the calcined alumina / volatile silica is 1 to 0.1 by mass ratio, and calcined alumina + alumina fine powder /
Most preferred is a ratio of volatile silica of 2-5. When the mass ratio of calcined alumina / volatile silica exceeds 1, sintering shrinkage tends to be large and the peel resistance tends to be poor. If it is less than 0.1, the fluidity is poor, and the workability tends to decrease. A more appropriate ratio is between 1 and 0.5. (Calcined alumina + alumina fine powder)
Even when the mass ratio of / volatile silica is less than 2, sintering shrinkage increases. If it exceeds 5, the fluidity is poor, and the workability tends to decrease. In the spray material composition, refractory aggregates other than the above-mentioned volatile silica, calcined alumina, and alumina fine powder of 75 μm or less are not particularly limited. For example, sintered alumina, fused alumina, bauxite, clay shale, mullite , Silica, chamotte, andalusite,
Pyrophyllite, silicon carbide, fused silica, magnesia, magnesia - _calcia, Al ₂ O 3 -MgO spinel, chromium ore, and one or more selected from sillimanite like. In addition, zirconia, carbon, clay, light burned magnesia,
One or more types selected from pitches and the like may be combined. The ratio of aggregates other than volatile silica, calcined alumina and alumina fine powder of 75 μm or less is not particularly limited. It is appropriately adjusted to coarse particles, medium particles, and fine particles in consideration of the fluidity and the filling property of the spray material. The spraying material generally contains a binder, an organic fiber, a dispersant (peptizer), etc. in addition to the refractory aggregate, but the specific type and ratio are not particularly different from those of the conventional method. If necessary, a metal fiber, a metal powder, a thickener, a lightening agent, a curing accelerator, a curing retarder and the like may be combined. Examples of the binder include alumina cement and magnesia cement. The addition ratio is 1 to 100% by mass of the refractory aggregate, and 1 to 4 depending on the type of the binder.
It is preferable to adjust within the range of 15% by mass. When the amount of the quick setting agent added at the nozzle portion is large, it is not always necessary to add the binder. Organic fibers have the effect of improving adhesion, and specific examples thereof include polypropylene, nylon,
PVA, polyethylene, acrylic, polyester, pulp and the like. Specific examples of metal fibers are stainless steel,
Iron, aluminum and the like. The optimal addition ratio is
Depends on the fiber material. The organic fiber is preferably 0.05 to 1% by mass and the metal fiber is preferably 0.5 to 7% by mass based on 100% by mass of the refractory aggregate. The dispersant has the effect of improving the flowability of the spray material. Specific examples thereof include sodium tripolyphosphate, sodium hexametaphosphate, sodium polyacrylate, sodium polyacrylate, polycarboxylic acid, and sodium ligninsulfonate. A preferable addition amount is 0.01 to 1% by mass based on 100% by mass of the refractory aggregate. Specific examples of the metal powder include aluminum, silicon, ferrosilicon, aluminum alloy, and silicon alloy. The addition amount is preferably 0.01% by mass based on 100% by mass of the refractory aggregate. Examples of the thickener include bentonite, CMC, isobutylene maleic anhydride strong polymer and the like, and the addition ratio thereof is preferably 5% by mass or less based on 100% by mass of the refractory aggregate.
The spraying material composed of the above-mentioned composition is sprayed beforehand adjusted in a sludge state by adding construction moisture. In this case, the construction moisture content is preferably 5 to 15% by mass of the outer spray composition as a whole. The quick setting agent added at the nozzle portion may be either liquid or powder. The liquid quick-setting agent is an aqueous solution of sodium aluminate, potassium aluminate, sodium silicate, sodium phosphate and the like. These liquid quick-setting agents are combined with a cationic or anionic flocculant, if necessary. Examples of powder quick setting agents include sodium aluminate, potassium aluminate, sodium silicate, sodium phosphate, sodium carbonate, calcium chloride, calcium hydroxide,
One or more selected from calcium oxide, calcium aluminate, magnesium hydroxide, Portland cement, sodium sulfate, and the like. When the powder quick setting agent is mixed with the refractory fine powder and added, the refractory fine powder combined with the powder quick setting agent can be selected from the refractory materials exemplified above as the refractory aggregate. The particle size of the refractory fine powder is adjusted to, for example, 0.05 to 0.5 mm on average within a range of 1 mm or less for use. If the average particle size is too small, it is affected by the wind pressure of the compressed air, and it is difficult to obtain the effect of continuous and stable addition to the spray material. Therefore, use of ultrafine powder such as volatile silica and calcined alumina is not preferable. The ratio of the powder quick-setting admixture and the refractory fine powder to be added at the nozzle portion is, for example, 15 to 80% by mass of the powder quick-setting admixture, and the remainder is refractory fine powder. If the powder quick-setting agent is less than 15% by mass, the effect as a quick-setting agent is insufficient, and the adhesion of the spray material tends to be poor. When the setting agent exceeds 80% by mass, the dispersibility of the setting agent in the spray material is poor. The proportion of the quick-setting agent added to the spray material (including the working water) adjusted into a slurry by adding the working water is 0.5 to 5 in terms of the solid content of the quick-setting agent from the viewpoint of the adhesion of the spray material. % By mass is preferred. Figure 1
3 is an image of a spray device in a spray method according to the present invention. The spraying material, which has been adjusted in advance into a slurry by adding the working moisture, is pumped into the nozzle (1) through the pumping pipe (5). The spray material is ejected from the nozzle while adding the quick-setting agent with compressed air from a quick-setting agent introduction pipe (2) connected near the tip of the nozzle (1). Then, a spray construction body (4) is formed on the wall surface (3) to be sprayed. In the same figure, the addition of the quick setting agent is in the nozzle (1),
It may be in the rear pumping tube (5). In the case of addition in the pumping pipe,
The distance until the spray material after the addition of the quick-setting agent is ejected from the nozzle becomes longer, and accordingly, the mixing of the spray material and the quick-setting agent becomes more reliable. The addition of the mixture of the powder quick setting agent and the refractory fine powder to the spraying material is performed with compressed air. Although not shown in the figure, a squeeze-type, screw-type, piston-type, rotary-type, or other pressure-feeding device is used to supply the spray material to the nozzle.

Examples Examples of the present invention and comparative examples are shown below. Tables 1 and 2 show the composition of the spraying material, the quick setting agent and the test results used in each example. The particle size of the refractory raw material specified in each example is determined by the laser diffraction method for volatile silica and calcined alumina.
It conforms to the IS sieve opening.

[Table 1]

[Table 2] In the spraying, the spraying material, which has been prepared in a sludge form by adding 10% by mass of construction moisture to the outside, is pumped by a squeeze-type pump, and the quick-setting agent in the nozzle is enveloped by compressed air.
２2% by mass (when mixing and adding a quick-setting admixture and refractory fine powder, the proportion excluding the refractory fine powder) was added and sprayed on the refractory vertical wall. In the adhesion test, the adhesion rate of the spray material was determined. The corrosion resistance was measured by a rotary erosion test on a test piece cut out from the sprayed construction body using an erosion agent composed of molten slag and pig iron. The results are shown as an index with the erosion dimension of Comparative Example 1 being 100, and the smaller the numerical value, the better the corrosion resistance. The residual line change rate and the spalling resistance were determined as indices of the peeling resistance. The residual line change rate is obtained by heating a test piece cut out from a sprayed body at 1450 ° C. × 3 hrs and expressing the residual line change rate after heating with respect to the dimension before heating in percentage. The smaller the residual change rate is, the smaller the sintering shrinkage is. The spall resistance was obtained by heating a test piece cut from a sprayed body at 1450 ° C. × 3 hrs.
It was quenched to give a thermal shock, and the degree of decrease in the elastic modulus was evaluated. The test value is an index of the elastic modulus after the application of the thermal shock, assuming that the elastic modulus before the application of the thermal shock is 100. The larger the numerical value, the higher the spall resistance. Workability is
It was comprehensively evaluated from the fluidity of the sprayed material in the material pumping and the degree of clogging of the pumping pipe, and was displayed in four stages of A to D. A
Is the most excellent in workability, and D is the lowest in workability. In the actual machine test, spray repair was performed on the lining of a mixed iron vehicle used in the steelmaking industry. It was sprayed to a thickness of about 100 mm, and the number of durable charges until the liner before repair was exposed by the operation of the mixed iron wheel was determined. Those with no test values were not tested. From the results shown in Tables 1 and 2, none of the examples of the present invention has the same color in adhesion and peel resistance. In some implementations, the use of a large amount of volatile silica has no remarkable effect on corrosion resistance, but the peel resistance of the present invention ultimately results in much better durability in actual machine tests. Among the examples of the present invention, Examples 10 to 18 shown in Table 2 are those in which the quick setting agent is added in a state of being mixed with the refractory fine powder. It is confirmed that each property of the spray material is more excellent. On the other hand, Comparative Example 1 uses a spraying material that contains volatile silica but does not contain calcined alumina, and is inferior in spall resistance and workability. In Comparative Example 2, although calcined alumina was added, the amount of volatile silica used was excessive, and the sintering shrinkage resistance, spall resistance, and workability were poor. Comparative Example 3, in which the calcined alumina was blended but the proportion of volatile silica was small, was inferior in sintering shrinkage resistance, spall resistance, and workability. Comparative Example 4 in which the proportion of calcined alumina is too large and Comparative Example 5 in which the amount of the alumina fine powder used is small are all inferior in sintering shrinkage resistance and spall resistance. FIG. 2 shows the amount of calcined alumina and the amount of the sprayed material in each of the three sprayed materials in which the amount of the volatile silica used was changed to 3, 8, and 15% by mass in the spraying method of Example 2 described above. It is the graph which showed the relationship with the residual line change rate. In this case, the amount of the fine alumina powder having a particle size of 75 μm or less is increased or decreased in accordance with the change in the amount of the volatile silica and the amount of the calcined alumina. The amount was adjusted to 32% by weight. From the results of this graph, it is confirmed that in the spray material in which the amount of the volatile silica, the amount of the calcined alumina, and the ratio of the alumina fine powder are within the range of the present invention, the sintering shrinkage is effective. In the above embodiments, the spraying target wall surface is at room temperature. However, the method of the present invention can obtain the same effect on a high-temperature wall surface as in hot repair of a furnace wall. The spraying method of the present invention is suitable for lining or repairing a hot metal vessel or a hot metal gutter such as a hot metal ladle, a mixed iron wheel, a mixed iron furnace, a blast furnace gutter,
It is also applicable to molten steel containers.

[Effect] As shown by the test results of the above examples, the present invention relates to a refractory spraying method in which a spray material adjusted in a slurry form is sprayed by adding a quick-setting agent in a nozzle. , And the peel resistance that determines the life of the sprayed material can be greatly improved. as a result,
ADVANTAGE OF THE INVENTION According to the refractory spraying method of this invention, the man-hour and the usage of the spraying material accompanying construction are reduced, and at the same time, it greatly contributes to the improvement of the operation rate of the installation target equipment.

[Brief description of the drawings]

FIG. 1 is an image diagram of a spraying method of the present invention.

FIG. 2 is a graph showing a relationship between a material of a spray material and a residual line change rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Quick-setting agent supply pipe 3 Wall surface 4 Spray construction body 5 Pumping pipe

Claims (5)

[Claims] 1. A refractory spraying method for spraying a spraying material which has been prepared in advance into a sludge state by adding working water and adding a quick-setting agent in a nozzle or a pressure feed pipe. The material composition is 6 to 13% by mass of volatile silica, 1 to 7% by mass of calcined alumina, 10 to 30% by mass of sintered alumina fine powder having a particle size of 75 μm or less and / or electrofused alumina fine powder,
A refractory spraying method in which the remainder is made of other refractory aggregate. 2. A refractory spraying method for spraying a spraying material which has been preliminarily adjusted into a sludge state by adding working water and adding a quick-setting agent in a nozzle or a pressure feed pipe. The composition is 6 to 13% by mass of volatile silica, 1 to 7% by mass of calcined alumina, 10 to 30% by mass of sintered alumina fine powder and / or electrofused alumina fine powder having a particle size of 75 μm or less, and the remainder is a refractory aggregate other than the above. And the calcined alumina / volatile silica in a mass ratio of 1 to 0.
1, [calcined alumina + (sintered alumina fine powder and / or fused alumina fine powder)] / a refractory spraying method in which the volatile silica is 2 to 5. 3. The refractory spraying method according to claim 1, wherein the quick-setting agent added in the nozzle or the pressure feed pipe is mixed with the refractory fine powder. 4 to 13% by mass of volatile silica, 1 to 7% by mass of calcined alumina, 10 to 30% by mass of sintered alumina fine powder and / or electrofused alumina fine powder having a particle size of 75 μm or less, with the remainder being refractory other than the above. Spraying material used as aggregate. 5 to 13% by mass of volatile silica, 1 to 7% by mass of calcined alumina, 10 to 30% by mass of sintered alumina fine powder and / or electrofused alumina fine powder having a particle size of 75 μm or less, with the remainder being refractory other than the above. As for the aggregate, the calcined alumina / volatile silica is 1 to 0.
The spraying material according to claim 4, wherein the ratio of [calcined alumina + (sintered alumina fine powder and / or fused alumina fine powder)] / volatile silica is 2 to 5.