JPH0357068B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a monolithic refractory that has excellent corrosion resistance, spalling resistance, and workability. Specifically, the present invention relates to a monolithic refractory that has excellent corrosion resistance, spalling resistance, and workability. The present invention relates to an amorphous refractory composition consisting of the following. Conventionally, for monolithic refractories that harden at room temperature, hydraulic alumina cement,
Clay, phosphate, etc. are used. However, when these substances are used as binders, the following drawbacks have been pointed out. That is, (1) When hydraulic alumina cement is used, it exhibits a decrease in strength in the intermediate temperature range of 500 to 1200°C, or an explosive phenomenon occurs when the temperature rises. (2) When clay is used as a binder, there is a problem with corrosion resistance at high temperatures. (3) In the case of phosphates, they are unfavorable from the perspective of steel quality, and when used in steelmaking, the amount of phosphates added is limited, so it is necessary to ensure that the resulting construction body exhibits sufficient strength. I can't. etc. On the other hand, in recent years, carbon bonds have been attracting attention due to their excellent strength at high temperatures, heat spalling resistance, and explosion resistance. As is well known, these are prepared using tar and pitch, but these tar and pitch not only have problems such as smoking, but are also said to contain carcinogenic substances. Its use is also said to pose environmental health problems. Furthermore, monolithic refractories using tar or pitch soften once during temperature rise and then generate carbon bonds, so they could not be used as lining structures for various molten metal containers. Therefore, in order to avoid the environmental and work problems mentioned above, we have developed thermoplastic resins that exhibit thermosetting properties by using thermosetting resins and curing agents such as hexamethylenetetramine. The methods used are attracting more and more attention. However, these resins themselves do not have curability at room temperature, so even if they can be used for shaped refractories, when used for monolithic refractories, they must be made curable at room temperature by some method. Methods for this purpose include: (1) A method in which alumina cement or phosphate is added to a resin that does not harden at room temperature, and the alumina cement or phosphate exhibits room-temperature hardenability. (2) A method of adding a curing agent such as sulfuric acid or para-toluenesulfonic acid to a thermosetting resin. There is. However, since method (1) is carried out by kneading with water, the resultant workpiece tends to explode due to evaporation of water when it is dried and heated, or even if it does not explode, it becomes porous, and the carbon bond cannot be bonded at high temperatures. Since the addition of the resin inhibits the formation of the resin, the effect of adding the resin cannot be fully exhibited. In addition, method (2) generally uses a liquid thermosetting resin as a wetter, so it is an ideal method from the point of view of generating carbon bonds.
This room temperature curing method is called acid curing and uses strong acids such as para-toluenesulfonic acid, benzenesulfonic acid, sulfuric acid, and phosphoric acid, so it can be applied to neutral or acidic refractory materials. It could not be applied to basic refractory materials such as magnesia and dolomite. That is, in the case of basic refractory materials, these strong acids as curing agents cause a neutralization reaction with the refractory materials, so that curing takes a long time or curing does not proceed. The present inventors have conducted various studies in order to obtain a room-temperature-curable monolithic refractory that eliminates the drawbacks of the prior art described above. The present inventors have discovered that room temperature curability can be imparted to the thermosetting resin by adding an organic compound selected from the group consisting of: That is, this invention uses basic refractory material as the main material,
1 selected from thermosetting phenolic resins, oxycarboxylic acids, amino acids, and amides.
The object of the present invention is to provide an amorphous refractory composition which has room temperature curability and is made of a material containing one or more organic compounds and, if necessary, an alkaline compound. The basic refractory materials used in this invention include various conventionally known basic refractory materials, including various magnesia refractory materials such as fused magnesia and sintered magnesia, stabilized dolomite, and synthetic dolomite. It is preferable to use one or more kinds of dolomite refractories as the main material, and to use them in combination with powdered or granular carbonaceous materials such as graphite and silicon carbide. In addition to thermosetting phenolic resins, thermosetting phenolic resins, modified resins thereof, and thermoplastic phenolic resins that become thermosetting by adding hexamethylenetetramine can be used as the thermosetting phenolic resin. Compared to other resins such as furan resins, phenolic resin has a large amount of residual carbon, and therefore has a high bonding strength, and also produces less odor during construction, drying, and heating as a monolithic refractory, and is less expensive. It has the characteristics of being inexpensive and easy to obtain. In addition, when used together with pitchchi, etc., it blends very well with pitchchi. Further, these resins may be used alone or in combination of two or more, and furthermore, thermoplastic resins, pitches, resinous pitches, organic solvents, etc. may be used in combination. The amount of this thermosetting phenolic resin used is 0.5 to 50% by weight, preferably 1.5 to 25% by weight based on the fireproof material. This is because if the amount of thermosetting phenolic resin is less than 0.5% by weight, carbon bonds will not be sufficiently generated, resulting in insufficient strength of the resulting construction, and if it is used in excess of 50% by weight, the volatile content will increase. This is because the physical properties and corrosion resistance of the constructed body after heat treatment deteriorate, which is undesirable. Furthermore, the organic compounds used in this invention include oxycarboxylic acids such as lactic acid, hydroxyvaleric acid, tartaric acid, and citric acid, α-amino acids,
These include amino acids such as β-amino acids, γ-amino acids, and δ-amino acids, and amides such as formamide, acetamide, and benzamide.
It is sufficient to use one species or a combination of two or more species. By using this organic compound in combination with an alkali component, it has become possible to obtain sufficient room temperature curability even when using a phenolic resin to which a solvent has been added to lower the viscosity. The amount of this organic compound used is 0.5 to 20% by weight, preferably 1 to 18% by weight, based on the basic refractory material. If the amount is less than 0.5% by weight, the thermosetting resin will not be able to fully exhibit its room temperature curing properties, will require a long curing time, or will lack strength after curing or lack of shape retention during heating. Moreover, if the content is more than 20% by weight, the physical properties and corrosion resistance of the resulting constructed body will be poor. Furthermore, in addition to the above-mentioned thermosetting phenolic resin and an organic compound selected from oxycarboxylic acids, amino acids, and amides, the combined use of an alkali component is also effective in controlling the curing speed of the resin at room temperature, and the present invention This is one of the characteristics of Contains basic refractory materials MgO and CaO, and when used in fine powder parts, it is not necessary to use alkaline compounds, but if the curing speed is slow, it is possible to adjust the speed by adding them. . Furthermore, since a basic refractory material is used, the presence of an alkaline component is preferable, considering that even weakly acidic materials have some degree of adverse effects. And the amount added is based on basic refractory material.
A suitable amount of NaOH is 1.5% by weight or less, preferably 1.0% by weight or less. In addition to NaOH, such alkaline components include KOH, _NH4 , OH, Ca(OH) ₂ , _CaCO3 ,
Inorganic alkali components such as Mg(OH) ₂ and organic alkali components can be used. The effect of the combined use of an alkali component is thought to be that the alkali component promotes a reaction in which organic compounds such as oxycarboxylic acids, amino acids, and amides create a crosslinked structure between thermosetting resins and cure. Since the monolithic refractory composition of the present invention has room-temperature curability, it is preferable to knead it at the construction site, but it can also be applied to the production of specially shaped shaped refractories. These construction methods include simple pouring, vibration molding, and ramming (including stamping), but depending on the application and construction method, the types of thermosetting phenolic resins and organic compounds, their combinations, etc. Just adjust the amount to be used. It can also be used as an adhesive for refractory mortar or ceramics. The advantages of the amorphous refractory composition of the present invention thus obtained are as follows. (1) It has room temperature curability regardless of the type of basic refractory material or carbonaceous material, and has excellent workability. (2) The curing speed of the construction object can be easily adjusted by simply changing the amount of organic compound and alkaline component used. (3) Unlike conventional castables, large amounts of water are not used, so there is no explosion or cracking when drying. (4) It has stable strength from room temperature to high temperature, and has excellent shape retention of the constructed structure. (5) Since the wetter (liquid component) that provides workability forms a carbon bond, it not only has greater bending strength at high temperatures than ceramic bond, but also has excellent heat spalling resistance. (6) Because it forms a carbon bond, it is difficult to leak into molten metal or slag and has excellent corrosion resistance. (7) Excellent adhesion to steel shells, bricks, etc. (8) Digestible refractory materials such as synthetic dolomite can also be used. Next, examples of the present invention will be described. Note that all parts and percentages stated in the formulation are parts by weight and percentages by weight. Examples 1 to 4 90 parts of magnesia and 10 parts of graphite with adjusted particle size
Liquid resol type phenolic resin (viscosity 90 cp, PH 6.8) in the amount shown in Table 1 for the refractory material consisting of
Add various organic compounds shown in the table, 10% aqueous sodium hydroxide solution, and fine magnesia powder,
The mixture was kneaded for about 3 minutes using a mortar mixer to obtain a monolithic refractory. Table 1 shows the results of measuring the workable time and curing time of this monolithic refractory. The workable time is defined as the free flow value measured at regular intervals after mixing using a mortar flow tester specified in JISR5201, and when the value is 150.
The time taken to show a value of mm or more was taken as the time. Further, the curing time was defined as the time until the hardness of the poured sample after kneading showed a value of 80 or more using a Green Birdness Tester manufactured by Shinto Kogyo. Comparative Examples 1-2 Regarding monolithic refractories obtained in the same manner as in Examples except that para-toluenesulfonic acid was used in the amount shown in Table 1 as a curing agent for phenolic resin,
I did a similar test.

[Table] As is clear from the test results in Table 1, even when basic refractory materials such as magnesia are used, thermosetting phenolic resins, oxycarboxylic acids, amino acids, and amides By using an organic compound in combination, it has curability at room temperature, and by selecting the type of organic compound,
Alternatively, it was confirmed that the curing speed could be adjusted by further adding sodium hydroxide or magnesia fine powder. On the other hand, in the acid curing method using para-toluenesulfonic acid as in the comparative example, the curing speed is slow, and when the amount added is increased to speed up the curing speed, heat generation due to neutralization reaction with the basic refractory material occurs.
It was found that foaming increased and it could not be used as a monolithic refractory. Furthermore, the monolithic refractory according to the present invention does not explode even if the temperature is raised immediately after demolding, but Comparative Example 1
The monolithic refractories exploded at 600℃. In addition, regarding spalling resistance, the monolithic refractories according to the present invention exhibited excellent durability that was 2.5 to 8 times that of the comparative examples.

Claims (1)

[Claims] 1 The main material is a basic refractory material, and the refractory material contains a thermosetting phenolic resin and one or two selected from oxycarboxylic acids, amino acids, and amides.
A monolithic refractory composition comprising a material containing at least one organic compound and, if necessary, an alkaline compound.