JP2597796B2 - Plastic refractories - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic refractory which has little drying / heat shrinkage and is excellent in workability.

[0002]

2. Description of the Related Art Plastic refractories are known as lining materials for kilns. The features of construction using plastic refractories include that a jointless integrated structure can be obtained compared to refractory bricks, and continuous construction using a rammer is possible.

[0003] Conventional plastic refractories include refractory aggregates,
A mixture of clay and binder mixed with water is used. For example, as disclosed in JP-A-48-74514.

[0004]

The main characteristics required for a plastic refractory are prevention of aging and workability during construction. Further, in order to take advantage of the characteristics of the integrated structure, shrinkage during drying and heating, which causes fire leakage, may be small.

The workability and shrinkage prevention of plastic refractories are controlled by adjusting clay and added moisture. If the refractory clay and the water content increase, the workability improves, but on the other hand, the shrinkage increases. If the refractory clay and the added water content are small, the shrinkage is small, but the workability is deteriorated such as poor compaction at the time of construction of the rammer. For this reason, the conventional material cannot have both shrinkage prevention and workability required for the characteristics of the plastic refractory.

[0006]

Means for Solving the Problems The present inventors have conducted studies to solve the above-mentioned conventional problems in plastic refractories. As a result, by adding a specific type of dispersant and organic binder in combination, even if the refractory clay and moisture, which greatly affect shrinkage and workability, are reduced, materials that do not lose the properties required for plastic refractories Was obtained, and the present invention was completed.

A feature of the present invention is that the refractory clay 5
~ 20% by weight, with the balance being based on a refractory aggregate,
Externally, 0.01 to 1% by weight of sodium silicate and / or acrylic acid-based dispersant and 0.01% of alginic acid-based binder
It is a plastic refractory to which 〜1% by weight is added.

Hereinafter, the present invention will be described in more detail.

The refractory clay has a role of enabling a driving work due to its plasticity. The compounding ratio is 5-2
0% by weight. For conventional plastic refractories,
The proportion of the clay is about 10 to 30% by weight, but in the present invention, even if the lower limit is 5% by weight, sufficient filling properties can be obtained. In order to suppress shrinkage, the upper limit is set to 20% by weight.

The refractory aggregate is made of, for example, alumina, silica, silica-alumina, spinel, chromite or the like, and is used by adjusting the particle size to coarse, medium and fine as in the case of conventional materials.

The sodium silicate as a dispersing agent is preferably 1 to 3. As the acrylic acid, acrylic acid, sodium methacrylate, methacrylic acid and the like can be used. FIG.
Is a plastic refractory made of 10% by weight of refractory clay, the balance of which is adjusted to coarse, medium, and fine particles in a plastic refractory. Sodium silicate No. 1 as an example of sodium silicate, and sodium methacrylate as an example of acrylic acid. And add
It shows the relationship between the added amount and the workability index.

The workability index is:
JIS-R for measuring plastic deformation of plastic refractories
2574. If the workability index value is high, the workability such as excellence in cracking due to flexibility is improved.

FIG. 1 shows that the addition of a suitable amount of sodium silicate No. 1 or sodium methacrylate dispersant increases the workability index value and improves workability. However, the addition of these sodium silicate and acrylic acid-based dispersants causes thixotropic (fluidity generated by vibration during driving).
Recovery is delayed, causing a decrease in the strength of the construction body and dropping during driving. In the present invention, this problem has been solved by further adding an appropriate amount of an alginic acid-based binder.

In a plastic refractory in which chamotte adjusted to coarse, medium, and fine particles is used as an aggregate and 10% by weight of refractory clay is added, 0.5% by weight of sodium silicate No. 1 is used.
For each of the added material, the material added with 0.5% by weight of sodium methacrylate, and the material not added with the dispersing agent, sodium alginate was added as an example of an alginic acid-based binder, and the amount added, the strength of the construction body and 2 is the graph of FIG.

From FIG. 2, it is confirmed that the strength of the construction refractory of the plastic refractory to which sodium silicate No. 1 or sodium methacrylate is added can be improved by adding an appropriate amount of sodium alginate. In addition, plastic refractories to which neither sodium silicate 1 nor sodium methacrylate is added have no problem such as dripping, but have a very large caking power of sodium alginate, and therefore have poor filling properties and poor construction strength. .

FIG. 3 is a graph showing the strength of the construction of the plastic refractory shown in FIG. 2 when a general CMC (carboxy methyl cellulose) is added as a binder in place of sodium alginate. It is a thing. From this graph, it is understood that the material to which sodium silicate No. 1 or sodium methacrylate is added does not have sufficient strength of the construction body even when CMC is added. This is considered to be because CMC is inferior in binding power as compared with alginic acid binders.

Materials known as dispersants exist in addition to sodium silicate and acrylic acid. However, the selection of sodium silicate or sodium acrylate exhibits the effect of the present invention in combination with an alginic acid-based binder. Other dispersants require lower workability index values for plastic refractories.

If the addition ratio of sodium silicate and / or acrylic acid-based binder is less than 0.01% by weight, the effect of the addition is not confirmed, and if it exceeds 1% by weight, even in combination with alginic acid-based binder. Drops and the like occur, and the strength of the construction body becomes insufficient.

The alginic acid binder used in the present invention comprises:
Even if stored for a long time in high temperature such as summer, for example, C
Since it does not rot like MC, its effect is not degraded, and it is also effective in preventing aging.

Specific examples of the alginate-based binder include sodium alginate, amine alginate, ammonium alginate, calcium alginate and the like.

The addition ratio of the alginic acid-based binder is 0.0
If it is less than 1% by weight, the strength of the construction body is inferior. If it exceeds 1% by weight, the viscosity at the time of construction becomes excessive and the workability is inferior.
The shrinkage increases due to poor filling.

The material according to the present invention is indispensable for the above-mentioned blends. In addition to these, there are known additives for plastic refractories, for example, fibers, refractory ultrafine powder, refractory hollow particles and the like. A small amount may be added.

[0023]

Examples Examples of the present invention and comparative examples are shown. Table 1
It is the composition and the test result of each example.

[0024]

[Table 1]

[0025]

[Table 2]

The test method is as follows.

Workability index; JIS-R
It was measured according to 2574.

Compressive strength: JIS-R25 after drying the substrate
It measured according to 75.

Drying shrinkage: Shrinkage due to drying at 110 ° C. for 24 hours was measured according to JIS-R2554.

Firing shrinkage: The shrinkage due to firing at 1300 ° C. for 3 hours was measured according to JIS-R2554.

In the embodiment of the present invention, the workability index value is in the range of 20 to 30 which is optimal for workability. Also, it is excellent in the compressive strength of the construction body. Drying / firing shrinkage is also small.

On the other hand, Comparative Example 1 in which the ratio of sodium silicate No. 1 is larger than the range of the present invention and Comparative Example 2 in which the ratio of sodium methacrylate is larger than the range of the present invention have the compressive strength of the construction body. Low, causing dripping during construction. In Comparative Example 3 in which the amount of sodium alginate was larger than the range of the present invention, the compressive strength of the base material was high and the shrinkage was large because of poor filling properties.
In Comparative Example 4 using sodium lignin sulfonate as a binder, and Comparative Example 5 using CMC, the compressive strength of the construction body was low and no binding effect was exhibited. In Comparative Example 6 using a dispersant and no binder, the compressive strength of the construction body was low,
Drops will occur during construction. In Comparative Example 7 in which various additives were not added, workability was good in workability index value and green strength, but shrinkage was large.

The graph of FIG. 4 shows the results of a test on the relationship between the molding pressure and the drying shrinkage of the construction body for the materials of Example 8 and Comparative Example 7 corresponding to the conventional material. from this result,
It is confirmed that the material of Example 8 can obtain a construction having a small shrinkage even at a lower molding pressure as compared with Comparative Example 7. This is because, in the conventional material, the fireclay in the construction body has an orientation by hitting with a rammer, but in the present invention, the orientation of the fireclay is lost by adding a dispersing agent, and the compaction is good. it is conceivable that.

Further, the materials of Example 8 and Comparative Example 7 were actually applied to the side wall of the heating furnace, and the shrinkage of the applied body was tested by observing the change in the width of the scoraoin. Table 2 shows the results. Example 8 had a smaller shrinkage ratio than Comparative Example 7, had no problems such as prevention of fire leakage, and was excellent in workability.

[0035]

As is clear from the above test results,
The material of the present invention is a material having both workability and construction body strength required for a plastic refractory. In addition, since there is little shrinkage of the construction body, there is no fire leakage during use, and the number of repair man-hours for measures against fire leakage is greatly reduced. In addition, since the work can be performed with a low molding pressure, the number of hits at the time of performing the rammer can be reduced, and the work efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of a dispersant added and the workability index of a plastic refractory.

FIG. 2 is a graph showing the relationship between the amount of an alginate binder added and the strength of a plastic refractory construction body.

FIG. 3 is a graph showing the relationship between the amount of a CMC binder added and the strength of a construction body of a plastic refractory.

FIG. 4 is a graph showing a relationship between a molding pressure and a contraction rate of a construction body.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Ichikawa 1-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Harima Ceramics Co., Ltd. (72) Inventor Tetsuro Fujii 1-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Harima Ceramics Co., Ltd.

Claims (1)

(57) [Claims] 1 to 5% by weight of a refractory clay, with the balance being 0.01 to 1% by weight of a sodium silicate and / or acrylic acid-based dispersant, which is added to a composition mainly composed of a refractory aggregate. A plastic refractory containing 0.01 to 1% by weight of an alginate binder.