JP2017165594A - Alumina cement having long term stability, method for producing the same, and unshaped refractory using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing alumina cement having long term stability where the weathering of alumina cement is suppressed, thus deterioration of fluidity and delay in heat generation and curing when being mixing with water upon the application of an unshaped refractory are prevented, and also, sufficient strength is secured.SOLUTION: Provided is alumina cement having long-term stability and in which a filling defect is hard to occur upon application by covering the alumina cement with cycloalkanone being liquid at ordinary temperature and forming a firm bond to the alumina cement surface as a treatment agent, an unshaped refractory using the same, and a method for producing the unshaped refractory at a low cost.SELECTED DRAWING: None

Description

The present invention relates to an alumina cement that can be used in the field of refractories such as steel-related furnace materials, the field where corrosion resistance is required, such as lining of chemical plants, and the field of civil engineering and construction, and an amorphous refractory using the same. In particular, the present invention relates to an alumina cement having long-term stability, a method for producing the same, and an amorphous refractory using the same.

In the field of refractories, which is one of the major fields of use of alumina cement, the conventional furnace construction method using regular refractories is indefinite to save labor for construction by mechanization in recent years and to save resources for repairs. It has been converted to a furnace construction method using refractories. In the construction method using an irregular refractory, there is a need for mass construction using a pressure pump.

On the other hand, as one construction method for the amorphous refractory, a construction method is performed in which a material for an amorphous refractory mixed with alumina cement, refractory aggregate, and water is poured into a mold. However, in order to improve the fluidity and the filling property when casting the material for the irregular refractory material, even if the vibration is applied using a vibrator such as a rod-like vibrator, There was a case.

Moreover, the strength of the construction body after pouring construction of the irregular refractory may be low, and the construction body has a risk of collapsing after removing the formwork. Among the castable constituent materials, alumina cement greatly affects the fluidity at the time of pouring construction, the curing characteristics, and the strength development at the time of deframement.

Alumina cement absorbs moisture in the air during storage, causes a very slight hydration reaction, and simultaneously sucks CO ₂ in the air. This is a weathering phenomenon of alumina cement. Due to weathering, if the amount of kneaded water is the same, the alumina cement is less fluid, heat generation / hardening is slow, and strength is also reduced.

Various methods have been studied as a method for preventing weathering of this alumina cement. However, methods that cut off contact with air as much as possible, such as increasing the thickness of packaging materials, increasing the number of packages, increasing the thickness of vinyl inside bags, and packing in bags of vinylidene chloride, etc., have sufficient effects. I couldn't. Major preventive measures such as reducing ventilation in the storage area were desirable, and good weathering prevention measures were desired.

Patent Document 1 provides an alumina cement having a long-term stability by containing fatty acids in an alumina cement, and an amorphous refractory using the same. Patent Document 2 proposes a method of treating alumina cement in a steam atmosphere of a water repellent such as silicone, paraffin, water-soluble polymer and fatty acids.

By treating the fatty acid shown in Patent Document 1 or the water repellent shown in Patent Document 2 with alumina cement, it becomes possible to provide an alumina composition that prevents weathering and has long-term stability. However, since these treatment agents are only physically attached to the surface of the alumina cement, they can be easily peeled off by friction between the alumina cement during transportation, etc., and sufficient weathering prevention effects cannot be obtained. was there.

On the other hand, in Patent Document 3, an organic compound having at least two hydrophilic functional groups such as adipic acid and one hydrophobic chain is contained in the cement, so that the metal cation in which the hydrophilic functional group is present in the cement is contained. By reacting with ions, the effect of delaying the water absorption rate is obtained. However, the melting points of the treatment agents such as adipic acid proposed in Patent Document 3 are all at a high temperature of 100 ° C. or higher, and in order to obtain a sufficient weathering prevention effect, they are heated to 140 ° C. to 170 ° C. There is a problem that it is necessary to process, and in order to process a large amount, the cost increases in terms of equipment.

Japanese Patent Laid-Open No. 2-97443 JP 2005-89230 A Special Table 2004-536015 gazette

As a result of intensive studies to solve the above-mentioned problems, the present inventor has selected a treatment agent that is liquid at room temperature and forms a strong bond on the surface of the alumina cement. The present invention has been completed by obtaining knowledge about a low-cost manufacturing method of an amorphous refractory material using alumina and an alumina cement having long-term stability.

That is, the present invention is an alumina cement having long-term stability and an amorphous refractory using the same, and an alumina cement having a surface coated with cycloalkanone and an amorphous refractory using the same. Preferably, the cycloalkanone is at least one selected from cyclopentanone, cyclohexanone, and cycloheptanone, and an alumina cement and an amorphous refractory using the same. The present invention is also a method for producing an alumina cement, characterized in that the cycloalkanone is mixed or mixed and ground with an alumina cement.

From the present invention, by selecting cycloalkanone as a treatment agent that is liquid at normal temperature and forms a strong bond on the surface of the alumina cement, it has long-term stability and is unlikely to cause poor filling during construction. It becomes possible to provide a low-cost manufacturing method of an amorphous refractory and an amorphous refractory using the same.

Hereinafter, the present invention will be described in detail.

Here, the alumina cement is an alumina raw material and calcia raw material, etc., mixed or mixed and pulverized, or further mixed and pulverized after partial mixing, and blended so as to have a predetermined component ratio, 1,300 to 1,800 ° C. The clinker obtained by melting and / or firing at a temperature of 1 is pulverized by a pulverizer. As the alumina raw material, high-purity alumina obtained by refining a natural raw material such as red bauxite by a purification method such as a buyer process, bauxite, or the like is used, and limestone, quick lime, or the like is used as the calcia raw material.

When manufacturing by a melting method, equipment such as an electric furnace, a reflection furnace, a vertical furnace, and a flat furnace, and when manufacturing by a firing method, equipment such as a shuttle kiln or a rotary kiln is used. In the pulverization of the clinker, pulverizers such as a roller mill, a jet mill, a tube mill, a ball mill, and a vibration mill that are used for fine pulverization of a normal powder lump are used.

The cycloalkanone according to the present invention is a ketone constituting a ring skeleton. In the present invention, alumina cement and a cycloalkanone as a treating agent are used in combination, preferably a cycloalkanone having 5 to 7 carbon atoms, and specific examples are selected from cyclopentanone, cyclohexanone, and cycloheptanone. There may be mentioned at least one or more cycloalkanones.

In particular, since these cycloalkanones having 5 to 7 carbon atoms have a melting point of 0 ° C. or less and are liquid at room temperature, they are sufficiently weathered by mixing or pulverizing at room temperature in the mixing and coating treatment of alumina cement. The effect of prevention can be obtained, and the cost during processing can be reduced. In addition, these cycloalkanones having 5 to 7 carbon atoms have a boiling point of 100 ° C. or higher and are relatively difficult to volatilize, and are volatilized from alumina cement by sealing with a packaging material such as vinyl that is normally used. The effect of preventing weathering is maintained.

In addition, these keto-type cycloalkanones have keto-enol tautomers, but cyclic compounds such as cycloalkanones are likely to enolize easily and chemisorb with alumina cement. Furthermore, it is considered that cycloalkanone having a cyclic structure has small steric hindrance and high chemical activity on alumina cement. Further, compared with phenol having the same hydrophilic functional group, the cycloalkanone having 5 to 7 carbon atoms is less harmful to the human body and is less likely to cause health problems in handling.

The amount of cycloalkanone that is a treatment agent used in the present invention is preferably in the range of 0.001 to 5 parts by mass, more preferably 0.01 to 2 parts by mass with respect to 100 parts by mass of the alumina cement. . If it is less than 0.001 part by mass, the effect is poor. If it exceeds 5 parts by mass, the delay of the hydration reaction of the alumina cement becomes significant, which is not preferable.

As a method for producing an alumina cement according to the present invention, there are a method of mixing alumina cement and a treating agent, and a method of mixing and grinding alumina cement and a treating agent.

The method for mixing the alumina cement and the treatment agent is not particularly limited. Each material is blended so as to have a predetermined ratio, and can be uniformly mixed using a mixer such as a V-type blender, a cone blender, a nauter mixer, a pan-type mixer, and an omni mixer. The mixing time is not particularly limited, and has an optimum value depending on the mixer, but is preferably 5 minutes or more, and more preferably 15 minutes or more. There is no upper limit for the mixing time.

As a method of mixing and pulverizing the alumina cement and the treating agent, there is a method in which materials previously mixed or weighed into a pulverizer are individually put and mixed inside the pulverizer. Although it does not limit as a grinder to be used, it can obtain by grinders, such as a ball mill, a vibration mill, a tower mill, a roller mill, a jet mill. Further, the feed amount at the time of pulverization is not particularly limited, but is preferably 0.05 to 20 t / hr, and more preferably 0.5 to 5 t / hr.

As the refractory aggregate of the amorphous refractory of the present invention, the refractory aggregate usually used for the amorphous refractory can be used. Specifically, molten magnesia, sintered magnesia, natural magnesia, And magnesia such as light calcined magnesia, magnesia spinel such as fused magnesia spinel and sintered magnesia spinel, alumina such as fused alumina, sintered alumina, light calcined alumina, and easily sintered alumina, silica fume, colloidal silica, light calcined alumina, Ultra fine powder such as easily sintered alumina, etc., fused silica, calcined mullite, chromium oxide, bauxite, andalusite, sillimanite, chamotte, quartzite, rholite, clay, zircon, zirconia, dolomite, perlite, vermiculite, brick waste , Ceramic scrap, silicon nitride, boron nitride, silicon carbide, and silicon nitride The use of iron, etc. is possible.

The amount of the refractory aggregate used is preferably 80 to 99 parts by mass and more preferably 90 to 97 parts by mass in 100 parts by mass of the amorphous refractory made of alumina cement and refractory aggregate. If the refractory aggregate is less than 80 parts by mass, sufficient fire resistance may not be obtained. If the refractory aggregate exceeds 99 parts by mass, the adhesion of the refractory aggregate is weakened, and there is a risk of poor curing or collapse. There is.

The method for producing the amorphous refractory used in the present invention is not particularly limited, but in accordance with the usual method for producing an irregular refractory, each constituent raw material is blended in a predetermined ratio, A uniform mixing method using a mixer such as a V-type blender, a cone blender, a Nauta mixer, a pan-type mixer, and an omni mixer is possible.

Hereinafter, the present invention will be further described based on examples.
[Examples 1 to 4]
After treating the treatment agent shown in Table 1 with respect to 100 parts by mass of the alumina cement, it was mixed for 20 minutes by an omni mixer. Next, 25 kg of ordinary paper bags (from the outermost package, craft → craft → craft → lamicoat) were filled and sealed, and then stored in a constant temperature and humidity chamber of 40 ° C. × 80% RH for 24 hours. Weigh the alumina cement after storage and the specified amount of refractory aggregates I, B, C, D, E, F, G and Additives A and B shown in Table 2 and mix for 15 minutes in a V-type blender. It was. Table 1 shows the results of paste flow values of these castables.

<Materials used>
Alumina cement: High alumina cement (Denka)
Treatment agent used in Example 1: Cyclopentanone (manufactured by Wako Pure Chemical Industries)
Treatment agent used in Example 2: Cyclohexanone (manufactured by Wako Pure Chemical Industries)
Treatment agent used in Example 3: Cycloheptanone (manufactured by Wako Pure Chemical Industries)
Treatment agent used in Example 4: cyclopentanone (manufactured by Wako Pure Chemical Industries) + liquid paraffin (manufactured by Wako Pure Chemical Industries)
Refractory aggregate a: Sintered alumina, particle size 6-14 mesh (Malco T-60)
Refractory aggregate b: sintered alumina, particle size 14-28 mesh (M-60 Morocco T-60)
Refractory aggregate C: sintered alumina, particle size 28-48 mesh (M-60 Morocco T-60)
Refractory aggregate D: Sintered alumina, particle size ~ 48 mesh (Moralco T-60)
Refractory aggregate E: Fine alumina (Sumitomo Chemical AM21)
Refractory aggregate: Ultra fine alumina (Alcoa A161SG)
Refractory aggregate: Silica fume (971U made by Elchem)
Additive A (dispersant): sodium tripolyphosphate (Wako Pure Chemical Industries)
Additive B (Curing retarder): Boric acid (Wako Pure Chemical Industries)

<Paste flow measurement method>
The measurement was carried out in a constant temperature and humidity chamber of 20 ° C x 80% RH. Measured according to JIS R2521, with a water / castable ratio of 0.058 in terms of mass ratio. The paste is filled in a flow cone placed at a predetermined position in the center of the flow table, and the surface is smoothed. Next, the flow cone is removed upward, and the maximum spread diameter of the paste and the direction perpendicular to it are measured with a caliper, and the average value is displayed in mm.

[Comparative Examples 1-3]
Alumina cement that has not been subjected to the mixing treatment with the treating agent, and alumina cement that has been treated in the same manner as in Examples 1 to 4 using cyclohexane or liquid paraffin as the treating agent, is maintained at the same temperature as in Examples 1 to 4. Table 1 shows the results of measurement of the castable paste flow values similar to those of Examples 1 to 4 after storage in a constant humidity chamber for 24 hours.

<Materials used>
Treatment agent used in Comparative Example 2: Cyclohexane (manufactured by Wako Pure Chemical Industries)
Treatment agent used in Comparative Example 3: Liquid paraffin (manufactured by Wako Pure Chemical Industries)

From the results of Table 1, it can be seen that there is little decrease in the paste flow values of Examples 1 to 4 compared to Comparative Examples 1 to 3, and by treating cycloalkanone as a treatment agent, the effect of moisture absorption suppression is achieved. It was confirmed that the paste flow value was improved. High fluidity when pouring the material for the amorphous refractory, and the effect of preventing poor filling can be obtained.

[Examples 5 to 8]
After the alumina cement subjected to the same treatment as in Examples 1 to 4 is stored in a constant temperature and humidity chamber for 24 hours under the same conditions as in Examples 1 to 4, predetermined amounts of the refractory aggregates i, b, C, D, E, F, G, and Additives A and B were weighed and mixed in a V-type blender for 15 minutes to make a castable. Table 3 shows the results of curing time, heat generation time, and 24-hour curing strength (compressive strength) when an amorphous refractory was produced using these castables.

<Curing time>
The measurement was carried out in a constant temperature and humidity chamber of 20 ° C x 80% RH. When the paste kneaded in the same manner as in Examples 1 to 4 with a water / castable ratio of 0.058 in mass ratio was measured, the time until the kneaded product did not dent when touched with a finger was measured.

<Fever time>
Put the paste prepared in the same way as the curing time measurement into a poly beaker, put it in a heat insulating container, insert a resistance temperature detector, measure the exothermic curve with a recorder, and start the kneading and then the exothermic curve will peak. Measure the time to reach.

<24-hour curing strength>
An amorphous refractory prepared using a paste prepared in the same manner as the measurement of the curing time was placed on a 4 × 4 × 16 cm mold with stamping with a stick, and the surface was flattened with a cement knife. Measure the compressive strength after time curing (20 ° C).

[Comparative Examples 4 to 6]
Example 1 for alumina cement not subjected to the mixing treatment with the treating agent as in Comparative Examples 1 to 3, and alumina cement subjected to the same treatment as in Examples 1 to 4 using cyclohexane or liquid paraffin as the treating agent After curing in a constant temperature and humidity room for 24 hours under the same conditions as in ~ 4, using these castables, the curing time, heat generation time, and 24-hour curing strength when producing an amorphous refractory similar to those in Examples 5-8 ( The results of compression strength) are shown in Table 3.

From the results in Table 3, compared with Comparative Examples 4 to 6, the curing time and the heat generation time are longer in the preparation of the irregular refractories of Examples 5 to 8, which is advantageous as the pot life, and prevents filling failure. The effect is obtained. Further, the strengths of the amorphous refractories of Examples 5 to 8 are also equal to or higher than those of Comparative Examples 4 to 6, and there is no problem in strength due to the treatment of cycloalkanone with alumina cement.

By using cycloalkanone that is liquid at normal temperature and forms a strong bond on the surface of the alumina cement as the treating agent, it has alumina cement that has long-term stability and is unlikely to cause poor filling during construction. It becomes possible to provide a low-cost manufacturing method for an amorphous refractory and an amorphous refractory.

Claims (4)

  Alumina cement with cycloalkanone coated on the surface.   Alumina cement, wherein the cycloalkanone is at least one selected from cyclopentanone, cyclohexanone, and cycloheptanone.   The method for producing an alumina cement according to claim 1 or 2, wherein cycloalkanone is mixed or mixed and ground with alumina cement. A method for producing an amorphous refractory produced by a construction method in which at least a refractory aggregate and an amorphous refractory constituent material comprising the alumina cement according to claim 1 or 2 is mixed with water and poured into a mold.