JPS6026065B2 - Manufacturing method for basic refractories - Google Patents

Description

[Detailed description of the invention] The present invention provides dolomite clinker, lime clinker, etc.
This invention relates to a method for producing an unfired and amorphous basic refractory using clinker containing free Ca○.

For example, basic refractories using dolomite clinker are used in large quantities in steelmaking furnaces such as LD converters, and this type of refractory has extremely excellent corrosion resistance against basic slag. It is to do so.

Conventionally, this type of refractory uses pitch as a binder,
Tarred dolomite bricks are made by baking at a temperature of 300 to 50 degrees centigrade, and fired dolomite bricks are the most common, which are made by molding and firing using tar or thermoplastic resin as a primary binder. In addition to this, various other monolithic refractories are manufactured using dolomite clinker, but the main binder is pitch.

Tarred dolomite bricks are advantageous over fired dolomite bricks in terms of energy savings, spalling resistance, and cost. However, in terms of manufacturing, they suffer from deterioration of the working environment due to low-boiling compounds in the pitch generated during heating and crosstalk, and Air pollution due to harmful substances generated during the process of stacking seed bricks in a furnace and raising their temperature has been raised as an extremely important issue.

Similar problems have also been raised regarding monolithic refractories that use pitch as a binder. The present invention aims to eliminate the adverse effects associated with the use of such pitches and to provide a non-scaling refractory and a monolithic refractory containing free Ca, which contribute to energy saving.

Various types of dolomite clinker for refractories are manufactured, but it is generally known that 20 to 7% by weight of dolomite clinker is Ca○, and most of this exists as free Ca○. It is.

This free Ca0 easily reacts with water and causes a change in volume, the so-called "quenching Q phenomenon", which is the biggest drawback of dolomite refractories. Therefore, using dolomite clinker containing free Ca0, unfired refractories,
When manufacturing monolithic refractories, binders such as alkali silicate, alkali phosphate, and colloidal silica that are used in general refractories are completely inappropriate, and non-aqueous binders are required. It is said that

Phenol resins have been attracting attention in recent years from the above viewpoints. Among phenolic resins, resol type cures by condensation reaction in a temperature range of 100 to 20 mm, but the condensed water released at this time rapidly digests the dolomite raw material, which is not preferable. On the other hand, novolac-type phenolic resins using hexamethylenetetramine as a curing agent do not exhibit the remarkable detoil phenomenon that is seen with the Hizol type, but they do not show the noticeable detimilation phenomenon that occurs when they are cured by heating or during the process of heating up a refractory in a furnace. It is also known that cracks occur due to digestion and deteriorate the refractory structure. For this reason, phenolic resins have not been put to practical use in refractories containing dolomite raw materials, even though they have fixed carbon comparable to pitches. Here, the present inventors investigated the cause of phenolic resin causing the effacement phenomenon, and by modifying phenolic resin using a special method, it became possible to use dolomite raw material containing free Ca○. .

The decomposition of phenolic hydroxyl groups and the use of hydrophilic solvents are thought to be factors in digestion associated with the use of nopolak-type phenolic resins. Monohydric alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol, and polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin are generally used as solvents for phenolic resins, but all of these are hydrophilic solvents. It has the highest hygroscopicity compared to dolomite raw material. Also, according to research on phenolic resin chemistry, 3 plates. It has been reported that a large amount of water is generated in an atmosphere near zero, and this is presumed to be due to the decomposition of phenolic hydroxyl groups.

The present invention consists of using a modified phenolic resin that eliminates the above-mentioned digestive factors, and the phenolic resin used in the present invention will now be explained.

The reaction between a novolac type phenolic resin and an alkylene carbonate, such as propylene carbonate, is carried out quantitatively at 140 to 200°C under the catalyst of an alkali metal carbonate, and in this case, the phenolic hydroxyl group is converted into a hydroxyalkyl ether. be converted into

In addition, unreacted alkylene carbonate or alkylene carbonate present in excess is a colorless, brachy-odor, non-hygroscopic, non-corrosive stable liquid at room temperature, and can serve as a solvent for the modified phenolic resin. Further, in order to explain in detail the phenolic resin used in the present invention, production examples are shown below. Production example 1 9 lbs of novolac type phenolic resin (softening point: 8 x 0) was collected in a Yotsuro flask, 200 ml of ethylene carbonate, 200 ml of propylene carbonate and 10 ml of potassium carbonate were added thereto, and the mixture was heated in a reflux condenser at a bath temperature of 150 qo. Add and mix thoroughly.

The modified phenol resin obtained after reacting for about 5 hours was a pale yellow liquid with a viscosity of 25 oise/2 viscosity and 0. Production example 2 Novolac type phenol resin is placed in a four-ring flask.
Propylene carbonate lk 9 and potassium carbonate 5 yen are mixed with this, and the mixture is concentrated and mixed with a reflux condenser at a temperature of 15 psi.

The modified phenol resin obtained after about 3 hours of reaction was a pale yellow liquid with a viscosity of 15 oise/25 qo. Production Example 3 9 lbs of novolac type cresol resin was collected in a four-volume flask, and 900 lbs of propylene carbonate and 5 lbs of potassium carbonate were mixed therewith, and the mixture was mixed with a reflux condenser at a temperature of about 150 qo.

The modified cresol resin obtained after 3 hours of reaction was a yellowish brown liquid with a viscosity of 10 oise/280.

The amount of phenolic hydroxyl groups remaining in the resin obtained in the above production example varies depending on the molar ratio with alkylene carbonate and reaction conditions, but it is not necessarily necessary to convert all phenolic hydroxyl groups into hydroxyalkyl ethers; Even denaturation has a significant effect on the digestion of free Ca0.

The phenols used as raw materials for the phenolic resin used in the present invention are not limited to the phenols and cresols mentioned in the production examples, but have one or more phenolic hydroxyl groups in one molecule, Any compound may be used as long as it has two or more vacant positions ortho or para to the phenolic hydroxyl group.

More specifically, phenol, cresol, chlorophenol, nonylphenol, butylphenol, phenylphenol, bisphenol A, phenolphthalein, resorcinol, methylresorcinol, hydroquinone, naphthol, isoprobenylphenol, etc. Can be mentioned. Of course, it is also possible to use a mixture of two or more of these phenols. The present invention consists of using a modified phenolic resin as shown in the above production example, and its feature is that it does not digest dolomite raw material containing free Ca0 no matter what proportion it is blended with. The point is that it enables the production of unfired refractories and monolithic refractories. In addition to the typical dolomite raw material having the chemical components shown in Table 1, the aggregate used in the present invention includes basic raw materials such as seawater magnesia and fused magnesia, and carbonaceous raw materials such as graphite and carbon black. be able to. In addition to dolomite clinker, raw materials containing free Ca○ include lightning calcia clinker and dawn calcia clinker, as shown in column D of Table 1.These high Ca○ calcia clinkers can also be used in the same way as dolomite clinker.

Table 1: The amount of modified phenolic resin used in the present invention is 2 to 2 to 10 parts by weight of aggregate in the case of unfired refractories.
5 parts by weight is preferred.

If the amount added is less than 2 parts by weight or more than 5 parts by weight, workability during molding will be poor, which is not preferable.

The amount added to monolithic refractories can be adjusted arbitrarily depending on the refractory construction method, but in the case of general stamp materials, 2 to 8 parts by weight per 10 parts by weight of Honemura 10 works well. Give sex. Such modified phenolic resin is usually used by adding 5 to 15 parts by weight of hexamethylenetetramine as a curing agent per 10 G parts by weight of the phenolic resin, but the amount of curing agent varies depending on the intended use of the refractory. It can be adjusted arbitrarily.

The present invention will be explained in more detail with reference to Examples below.

(Example 1) The modified phenolic resin prepared in Production Example 1 was kneaded, molded and dried (250°C) in a conventional manner to obtain unfired dolomite refractories as shown in the table below.

In that case, the characteristics of the refractory and the characteristics of the comparative product are
Shown in the table. In the case of the present invention, no cracks occur regardless of the type of dolomite, and the effect of the modified phenol resin is obvious. In addition, it was significantly superior in terms of quality compared to conventionally used tar dolomite refractories. Second
Table (Example 2) Using the modified phenolic resins of Production Examples 2 and 3, unfired dolomite as shown in the table below was produced in the same manner as in Example 1.
A graphite refractory was obtained.

Table 3 shows the properties of the refractory and the properties of comparative products. For reference, these were fired in coke for 140,000 cycles, but no expansion or cracking occurred, and they were bonded together with a strong carbon bond. In Examples 1 and 2 of Table 3, there was almost no odor during moat drilling, and the working environment was significantly improved compared to tar dolomite refractories.

(Example 3) The modified phenolic resins prepared in Production Examples 1 and 2 were kneaded in a conventional manner to obtain a dolomite stamp material.

As a result of stamping on a 200 x 200 x 200 skin frame and processing at various temperatures, products of good quality as shown in Table 4 were obtained.

The unfired dolomitic refractory consisting of B of Example 1 in Table 4 was used in a converter of Company A by laminating it with a tarred dolomite refractory.

Although no flaking due to spalling was observed in either case,
It was found that the final service size of the unfired dolomite refractory according to the present invention was clearly larger and that it had excellent corrosion resistance. Since there is no difference in the aggregate between the two, it is thought that the denseness of the refractory structure is responsible for their successful use.
(Example 4) Using the modified phenolic resin of Production Example 2, the unfired magnesia calcia carbon bricks shown in Table 5 were obtained by kneading, molding, and drying in a conventional manner.

While the quality of the general noporac type phenolic resin shown in Comparative Example 4 could not be measured due to expansion and cracking during drying, the bricks of x0 and xm using the resin of the present invention maintained good quality. Therefore, the effect of modified phenolic resin is clear. Table 5

Claims (1)

[Claims] 1. A method for producing a basic refractory, which comprises adding a phenolic resin modified with one type of alkylene carbonate or a mixture thereof to a clinker containing free CaO, kneading, molding, and drying.