JPH07237976A - Monolithic refractory for injection into blast furnace - Google Patents

Abstract

PURPOSE:To obtain a monolithic refractory for injection in a blast furnace, capable of repetitively using the same injection hole provided in a shell without causing deterioration in thermal conductivity due to the formation of pores. CONSTITUTION:This monolithic refractory for injection into a blast furnace contains 7-20 pts.wt. binder composed of a novolak type phenol resin containing hexamethylenetetramine mixed therein, 5-10 pts.wt. hardening accelerator composed of one or more of dihydric phenols, trihydric phenols, monohydric alkylphenols having an alkyl group substituted at the m-position and bisphenol A and one or more aromatic sulfonic acids, 20-40 pts.wt. solvent selected from polyhydric alcohols and higher alcohols and 0.7-3.0 pts.wt. organic flocculant soluble or compatible with the solvent in 100 pts.wt. total amount of 15-40 pts.wt. pitch having 150-250 deg.C softening point and 60-85 pts.wt. refractory aggregate having a controlled particle size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press-fitting amorphous refractory used for repairing a furnace body such as a blast furnace having a refractory lining inside a steel shell.

[0002]

2. Description of the Related Art For example, the lining of the bottom wall of the furnace bottom of a blast furnace is made of iron skin, stamp material, and carbon brick.
However, during operation, a gap is created between the steel skin and the stamp material, or between the stamp material and the carbon brick, which causes a decrease in thermal conductivity. Then, the cooling capacity from the outside (iron skin) decreases, and the temperature on the operating surface side of the carbon brick rises,
The rate of erosion of bricks increases. Therefore, such a problem is prevented by applying a press-fitting material to the gap between the iron skin and the stamp material or the stamp material and the carbon brick.

Conventionally, this type of amorphous refractory is composed of a granular or powdery refractory substance as an aggregate and an inorganic binder such as alkali silicate or phosphate, alumina cement, or coal tar pitch or petroleum pitch. It is common to prepare such an organic binder in an appropriate ratio, add a water or non-aqueous solvent as a workability-imparting agent, and use by injection.

The required properties of this type of amorphous refractory material are: (1) good adhesion to the steel skin;
(2) Good retention between the coke grains, (3) Good integration with coke, (4) Curing at 80 to 90 ° C within 2 hours to develop high hardness, etc. Listed.

The reason (4) is generally required is that in an operating blast furnace, when the furnace wall is damaged and red heat or cracks occur in the iron shell, water is sprayed on the iron shell to protect the iron shell. Since the refractory is injected during the rest of the blast furnace, the temperature near the iron shell in the furnace decreases with the passage of time from the rest, and by the time it actually hardens. , 80
This is because the temperature tends to be as low as ~ 90 ° C.
The above-mentioned amorphous refractory does not have such characteristics, and improvement measures have been studied conventionally.

[0006] In recent years, thermosetting resins have been mentioned as a binder for achieving such an object, and among them, phenol resins have been favored from the viewpoints of high carbonization yield, cost and raw material supply.

Phenolic resins are roughly classified into two series,
One is a resol-type phenol resin (hereinafter, resol-type resin), and the other is a novolac-type phenol resin (hereinafter, novolac-type resin). The former has a relatively low temperature (80-15
It cures sufficiently at 0 ℃), but since it contains free formaldehyde, it has a harmful effect on the human body during work. Since the latter does not contain free formaldehyde, the adverse effect of formaldehyde on the human body during work can be avoided, but it has the drawback that it does not cure sufficiently at a slightly high temperature (150 to 250 ° C).

[0008] Such adverse effects of the resol type resin are avoided, and curing at an appropriate temperature, an appropriate curing time, and a pot life (80 to 90 ° C,
In order to achieve (hardening within 2 hours), an amorphous refractory for press-fitting a blast furnace having the following composition, which is disclosed in Japanese Patent Publication No. 60-3035, has been developed. That is, (1) a granular or powdery refractory material, (2) a binder obtained by adding a curing material hexamethylenetetramine to a novolac type resin material, (3) a curing accelerator for phenols and aromatic sulfonic acid, (4) ethylene An amorphous refractory for press-fitting a blast furnace, which comprises a solvent selected from glycols or higher alcohols, and (5) a synthetic condensation type or synthetic polymerization type coagulant.

[0009]

[Problems to be Solved by the Invention]
The amorphous refractory for press-fitting a blast furnace disclosed in Japanese Patent Publication No. 60-3035 has the following drawbacks. If the repair needs to be performed again due to the operation, the press-fitting hole and its surroundings are already sufficiently hardened, so it is necessary to make a hole in the steel shell and install a separate press-fitting hole, which reduces the strength of the steel shell. Is a big problem.

Further, in the case of an amorphous refractory for press-fitting containing a novolac type resin, gas such as water vapor, CO and H ₂ is rapidly generated as the temperature rises (especially around 200 ° C.). The structure became porous, and the cooling capacity decreased as the thermal conductivity decreased, and there was a concern that the inner bricks would melt.

An object of the present invention is to overcome the above-mentioned problems, that is, to provide an irregular refractory for press-fitting a blast furnace in which the same press-fitting hole provided in the iron shell can be repeatedly used without causing a decrease in thermal conductivity. Is.

[0012]

[Means for Solving the Problems] The present inventors
The present invention has been completed by finding that the above problems can be solved by using a pitch having a softening point of 150 to 250 ° C. in addition to the amorphous refractory disclosed in JP-A-3035.

In the broadest sense, the present invention is based on the softening point.
Pitch of 150-250 ℃, refractory aggregate with adjusted particle size, binder made of novolac type phenol resin mixed with hexamethylenetetramine, dihydric phenol, trihydric phenol, alkyl group is substituted at meta position A curing accelerator composed of one or more kinds of monohydric alkylphenols and bisphenol A and one or more kinds of aromatic sulfonic acids, a solvent selected from polyhydric alcohols and higher alcohols, and dissolved in or in the same solvent. An amorphous refractory for press-fitting a blast furnace, characterized by being added with a soluble organic coagulant.

In a preferred embodiment of the present invention, the softening point of 150-
Refractory aggregate 60 with a pitch of 15 to 40 parts by weight at 250 ℃ and particle size adjustment
〜85 parts by weight, totaling 100 parts by weight, 7 to 20 parts by weight of a binder consisting of a novolac type phenol resin mixed with hexamethylenetetramine, divalent phenol, trivalent phenol and alkyl group substituted in the meta position. 5 to 10 parts by weight of a curing accelerator composed of one or more kinds of monovalent alkylphenols and bisphenol A and one or more kinds of aromatic sulfonic acids selected from polyhydric alcohols and higher alcohols. An amorphous refractory for press-fitting a blast furnace, comprising 20 to 40 parts by weight of a solvent and 0.7 to 3.0 parts by weight of an organic coagulant which is soluble or compatible with the solvent.

[0015]

Regarding pitch : Pitch, which is a characteristic additive in the present invention, has a softening point of 150 to 250 ° C., and concretely, there are coal tar type and petroleum type pitch, and the residual carbon amount is specified. Therefore, the softening point can be adjusted.

When the softening point is less than 150 ° C, it is dangerous that the softened pitch in the already-pressurized refractory flows out of the furnace when it is pressed in again, while the softening point exceeds 250 ° C. However, when press-fitting again, the press-fitting is impossible because the pitch in the refractory material that has already been press-fitted is hardened. The preferred softening point is 180 to 230 ° C.

The function of the pitch is as follows. The iron skin temperature (portion where refractory is injected) during press fitting is
250 to 300 ℃. Therefore, after press fitting, the phenol resin portion is completely hardened, but the pitch is softened and exists in a molten state in the phenol resin hardened structure.

Therefore, when the refractory material is press-fitted again for repair, it is possible to press-fit it through the softened and melted pitch, and it is not necessary to install a new press-fitting hole which has been necessary until now. Therefore, there is no concern that the strength of the iron skin will deteriorate, and the frequency of press-fitting repair can be sufficiently secured, and as a result, the effect of press-fitting repair can be dramatically improved.

Further, the effect of improving the thermal conductivity by the pitch is as follows. In the present invention, since the softening point uses a pitch of 150 ~ 250 ℃, even if the novolak type resin is made porous, since the softened and melted pitch fills the porous structure, the thermal conductivity is secured, As a result, an improvement in cooling capacity can be obtained. Therefore, a great effect is expected to be exerted on the suppression of melting loss of the carbon-based brick lined in the iron skin.

The grain size of the pitch is preferably 0.8 mm or less. The addition amount is 15 to 40 parts by weight, and more preferably 20 to 30 parts by weight. If the amount is less than 15 parts by weight, when trying to press-fit again from the same press-fitting hole, the softening / melting part is small, and press-fitting becomes difficult. On the other hand, if it exceeds 40 parts by weight, the ratio of the refractory aggregate decreases, and the strength of the irregular refractory for press-fitting decreases.

Regarding the refractory aggregate , the granular or powdery refractory material is one or a mixture of two or more materials such as alumina, siliceous, rholithic, carbonaceous, clay, etc. It has the grain size composition used for refractories. In terms of fluidity, the maximum particle size is 0.1
Particles of ~ 0.8 mm, 0.075 mm or less are desirable to be 40 wt% or less of the total aggregate.

Regarding Binder As the binder, a mixture of a novolac type phenol resin and hexamethylenetetramine added and compounded in the range of 5 to 25% with respect to the resin is used. The reason for using these is that there is little adverse effect on the human body as described above. The weight of the binder is 7 to 20 parts based on 100 parts of the refractory aggregate and the pitch. If the amount of the binder is 5 parts or less, the strength at a desired low temperature is not expressed even when used in combination with a curing accelerator, and it is unsuitable. Since there are problems such as poor deterioration and high cost, it is preferably 7 to 20 parts.

Curing Accelerator As a curing accelerator used for curing the press-fitting amorphous refractory at 80 to 90 ° C., the curing accelerator is compatible with the novolac type resin and the solvent and is active in curing the novolac type resin. Substances that cause hydration, that is, phenols that react with formaldehyde faster than normal phenol-formaldehyde reactions, specifically dihydric phenols, trihydric phenols, and alkyl groups substituted in the meta position 1 One or more of a valent alkylphenol and bisphenol A and one or more of an aromatic sulfonic acid are used. If the amount of the curing accelerator is 3 parts or less, the desired strength cannot be obtained, and even if 10 parts or more is added as a boundary, the effect of the curing accelerator is almost the same, so 5 to 10 parts is appropriate. is there.

Solvents Solvents are alcohols having a relatively high boiling point and a high flash point, and do not react with the novolac type resin, hexamethylenetetramine, the components of the above curing accelerator, and have good solubility. To do. Specifically, it is methanol, ethanol, ethylene glycol, diethylene glycol or the like. If the amount of the solvent added is less than 20 parts by weight, the viscosity is high and it is not suitable. Further, if it exceeds 40 parts by weight, the refractory structure deteriorates, so 20 to 40 parts is preferable.

The flocculant for aggregate is the viscosity of the pumpable repertoire in pumping machine, moreover, intended to be added to improve the retention of the between coke grains of the refractory, synthetic condensed flocculant Alternatively, a synthetic polymerization type coagulant (specifically, polyacrylamide or the like is used) is used. If the coagulant is less than 0.7 parts by weight, the desired refractory state cannot be obtained, and if it exceeds 3.0 parts by weight, the viscosity of the refractory becomes too high, and there is a problem in the pumpability of the refractory during press fitting. Since 0.7 to 3.0 parts by weight are produced, it is suitable.

[0026]

EXAMPLES The present invention will be specifically described below with reference to Examples. (Composition of irregular refractory for press-fitting) (1) 100 parts by weight of alumina refractory aggregate with adjusted particle size and petroleum pitch. Among them, petroleum pitch (softening point: 220
The addition ratio is shown in Table 1. (2) 10 parts by weight of a binder obtained by mixing a novolac type phenolic resin and hexamethylenetetramine (weight ratio 10: 1). (3) Resorcinol and p-toluenesulfonic acid were dissolved in ethylene glycol (weight ratio 1: 1: 2) curing accelerator 5
Parts by weight. (4) 25 parts by weight of a solvent consisting of ethylene glycol. (5) 1 part by weight of a coagulant of polyacrylamide and ethylene glycol (weight ratio 1: 200).

These samples were subjected to argon atmosphere at 5 ° C.
It was heated to 250 ° C. at a heating rate of / min and kept at that temperature for 5 hours. After cooling to room temperature, the apparent porosity and bulk specific gravity were measured and the cross-sectional structure was observed. The above test results are summarized in Table 1. Of the samples shown in Table 1, samples E and C are shown in FIGS. 1A and 1B and FIG.

A continuous pitch spreads like a mesh inside the structure of an irregular shaped refractory for press-fitting (Sample E) in which an appropriate amount of the pitch of the present invention shown in FIG. 1 is used, and a refractory aggregate + residual carbon portion is formed around it. 2 is spread in a suitable manner, but the one with a small amount of added pitch (Sample C) shown in FIG. 2 is not continuous because the pitch is surrounded by the refractory aggregate and the residual carbon portion.

This pitch was in a molten state at a temperature of 250 ° C., and Samples D and E could be pressed again through this softened melt. However, samples A, B, and C could not be press-fitted again because the pitch was not continuous. On the other hand, in sample F, the refractory aggregate was not fixed and the strength was low.

Further, the pitch-combined material of the present invention has a pitch entering the gap between the refractory aggregates, has a low apparent porosity and a high bulk specific gravity (indicating that there is little air having a low thermal conductivity). Addition of makes the structure dense and improves the thermal conductivity.

[0031]

[Table 1]

[0032]

EFFECTS OF THE INVENTION According to the present invention, it is possible to press an irregular shaped refractory for press-fitting many times through the same press-fitting hole through the softened melt (pitch). Therefore, it is possible to solve the problem of increasing the number of press-fitting holes, which is a drawback of the conventional low-temperature curable amorphous refractory material for press-fitting. Further, the structure of the press-fitting amorphous refractory can be densified, and the thermal conductivity, which is a necessary characteristic of the press-fitting amorphous refractory, can be improved. Therefore, the amorphous refractory for press-fitting of the present invention contributes to the extension of the life of the blast furnace and has great practical significance.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the results of observing the structure of Sample E, in which an appropriate amount of the pitch of the present invention is added, among the amorphous refractory samples for press fitting in the examples of the present invention.

FIG. 2 is an explanatory view showing the results of observing the structure of Sample C, in which a small amount of the pitch of the present invention is added, among the amorphous refractory samples for press fitting in the examples of the present invention.

Claims (1)

[Claims] 1. A softening point of 150 to 250 ° C., a pitch of 15 to 40 parts by weight, and a particle size-adjusted refractory aggregate of 60 to 85 parts by weight, 100 in total.
7 to 20 parts by weight of a binder composed of a novolac-type phenol resin mixed with hexamethylenetetramine, and a divalent phenol, a trivalent phenol, a monovalent alkylphenol in which an alkyl group is substituted in the meta position, and a bisphenol are used. 5 to 10 parts by weight of a curing accelerator composed of one or more kinds of A and one or more kinds of aromatic sulfonic acids, and 20 to 40 parts by weight of a solvent selected from polyhydric alcohols and higher alcohols. An amorphous refractory for press-fitting in a blast furnace, characterized in that the organic coagulant which is soluble or compatible with the solvent contains 0.7 to 3.0 parts by weight.