JP6427456B2 - Unshaped refractory composition and unshaped refractory - Google Patents

Description

  The present invention relates to a monolithic refractory composition and a monolithic refractory.

  Heretofore, it has been possible to easily pour and construct on the inner wall of a waste incinerator such as a rotary kiln furnace, and for the reason that the cost of the refractory can be reduced, the lining of a monolithic refractory is performed.

When a large amount of waste plastic or paint waste is incinerated in the rotary kiln, the temperature in the furnace may temporarily reach 1,500 ° C. to 1,600 ° C., and the incineration melts, It becomes a high temperature melt. In this state, if the molten material comes in contact with the monolithic refractory installed in the rotary kiln, the monolithic refractory penetrates and melts largely, and the life of the monolithic refractory becomes short. There is.
Therefore, as a method of extending the life of the monolithic refractory, for example, the content of chromia in the monolithic refractory is increased (see Patent Document 1), the proportion of alumina in the monolithic refractory is increased, and the proportion of silica is increased. A method of raising the eutectic point of the chemical composition component of the whole of the above-mentioned monolithic refractory has been proposed by lowering (see Patent Document 2) and the like.
However, in these proposed techniques, the chemical compositions of alumina, silica, chromia, and zirconia in the monolithic refractories are not optimized, and have penetration resistance and excellent corrosion resistance. It was not a thing.

JP, 2010-280540, A Unexamined-Japanese-Patent No. 6-122547

  An object of the present invention is to solve the above-mentioned problems in the prior art and to achieve the following objects. That is, the present invention is to provide a monolithic refractory composition and a monolithic refractory which can achieve both penetration resistance and erosion resistance, and are suitably used particularly for waste incinerators such as rotary kiln furnaces. With the goal.

The means for solving the problems are as follows. That is,
<1> Chemical composition containing 78% by mass to 83% by mass of alumina, 3% by mass to 7% by mass of silica, 8% by mass to 12% by mass of chromia, and 2% to 4% by mass of zirconia A monolithic refractory composition, wherein the alumina contains alumina particles having an alumina content of 99% by mass or more.
<2> The monolithic refractory composition according to <1>, wherein the raw material of the zirconia is zircon.
<3> The monolithic refractory composition according to any one of <1> to <2>, wherein the raw material of the alumina and the silica is electrofused mullite.
<4> The monolithic refractory composition according to <3>, wherein the addition amount of the electrofused mullite is 1% by mass or more and 29% by mass or less.
<5> The monolithic refractory composition according to any one of <1> to <4>, wherein the chromia is added in the form of powder.
<6> A monolithic refractory characterized in that the monolithic refractory composition according to any one of <1> to <5> is kneaded, shaped, and fired.
<7> The monolithic refractory according to <6>, which is for a waste incinerator.

  According to the present invention, it is possible to solve the problems in the prior art, to achieve both penetration resistance and erosion resistance, and in particular, to a monolithic refractory composition suitably used for waste incinerators such as rotary kiln furnaces, And monolithic refractories can be provided.

(Amorphous refractory composition)
The monolithic refractory composition of the present invention contains, as a chemical composition, alumina, silica, chromia and zirconia, and further contains other components as required.
Here, the monolithic refractory composition is a mixture of the components described above, and has a form in which the average particle diameter of the particles is 1 mm or less.

<Alumina (Al ₂ O ₃ )>
The alumina is contained in an amount of 78% by mass or more and 83% by mass or less and preferably 78% by mass or more and 81% by mass or less as the chemical composition. If the content is less than 78% by mass, the corrosion resistance may be poor, and if it exceeds 83% by mass, the contents of other components have to be reduced, so that the permeation resistance and the dissolution resistance The sex may be inferior.
The content of the alumina as a chemical composition can be measured, for example, by crushing the above-mentioned monolithic refractory, forming it into a uniform pellet, and measuring it with a fluorescent X-ray analyzer.
As a raw material of the said alumina, the alumina particle of 5 mm or less of average particle diameter can be used, for example, the alumina particle which grind | pulverized the alumina aggregate of 99 mass% or more of aluminas in the range of the said average particle diameter can be used. The alumina particles in this case preferably have a ratio of 50% or more to the alumina content in the composition. It is preferable to use electrofused mullite as another alumina raw material.

<< Alumina aggregate >>
Wherein the alumina aggregate, alumina _(Al 2 _{O 3)} refers to the aggregate comprising more than 99 wt%. As an advantage of using the alumina aggregate as a material, it is possible to suppress heat generation and contraction during chemical reaction by the aggregate, and to control cracks and the like.
The above-mentioned alumina aggregate is a particulate aggregate having a relatively smooth surface, which does not include those produced by crushing, and it is industrially included, for example, Al ₂ O ₃ ; 99% by mass or more. The high purity alumina aggregate etc. which consist of unavoidable impurities etc. are mentioned.

  The method for producing the alumina aggregate is not particularly limited, but a raw material prepared to have the above content is dissolved in an arc electric furnace or the like and finely granulated with high speed air or the like at the time of pouring (hereinafter referred to as “ Specific examples of the production method include a method of “melting method” and a method of atomizing and sintering the prepared raw material and sintering. Among these, the melting method is preferable because it is advantageous in terms of manufacturing cost. Further, the alumina aggregate obtained by the melting method is preferable because it is superior in heat resistance to the alumina aggregate obtained by crushing from a lump of sintered clinker or electrofusion clinker. This is because the alumina aggregate particles obtained by the above-mentioned melting method have a smooth surface having almost no unevenness on the particle surface and having a nearly spherical shape, whereas the alumina aggregate obtained by the above-mentioned crushing has a surface It is considered that the heat resistance is lowered because the reactivity is high because there are many irregularities generated by crushing.

There is also an alumina aggregate made by granulation as having the same advantages as the melting method. The said granulation method mixes the powder raw material adjusted so that it may become the said content, shape | molds a granule, and says the method of baking to make an aggregate. However, while the granulation method requires two steps of forming and firing of granules to become an aggregate after adjusting the raw material, the melting method becomes an aggregate in one step after adjusting the raw material In terms of cost, the melting method is desirable.
When the melting method is adopted as the manufacturing method, the type of melting furnace for melting the adjusted raw material is not particularly limited, but may be a heating type such as a burner, electric resistance, arc or coke. In particular, the arc type is preferable because high temperatures can be obtained relatively easily, the homogeneity of the melt is also high, and furthermore, the equipment of the furnace is simple and the operability is excellent.

There is no restriction | limiting in particular as an average particle diameter of the said alumina aggregate, Although it can select suitably according to the objective, 0.1 mm or more and 1.0 mm or less are preferable. Examples of the method of measuring the average particle diameter include a method of visually measuring a sample using a scale or the like.
It is preferable to add the said alumina aggregate by 60 mass% or more and 70 mass% or less with respect to the said monolithic refractory composition whole as a raw material.

<< 電 ラ イ ト >>>>
The electrofused mullite is a material containing alumina (Al ₂ O ₃ ) and silica (SiO ₂ ). The content ratio of the alumina and the silica is 72% by mass of alumina and 28% by mass of silica.
Although the silica contained in the electrofused mullite lowers the eutectic point, it is possible to prevent the contamination of extraneous components.
The electrofused mullite is preferably added as a raw material to the monolithic refractory composition at 1% by mass or more and 29% by mass or less.

<Silica (SiO ₂ )>
The silica is contained in an amount of 3% by mass to 7% by mass and preferably 5% by mass to 7% by mass as the chemical composition. If the content is less than 3% by mass, permeation resistance may be poor, and if it exceeds 7% by mass, the contents of other components have to be reduced, so that the corrosion resistance may be poor. There is sex.
The content of the silica as a chemical composition can be measured by the same method as the content of the alumina as a chemical composition.
As a raw material of the said silica, although you may use a silica alone, it is preferable to use the said electrofusion mullite and the zircon mentioned later. When the electrofused mullite is used, both penetration resistance and erosion resistance can be achieved. When the zircon is used, the mullite is formed together with the alumina when the silica contained in the zircon dissolves at high temperatures, so the electrofusion mullite can be used even without using the electrofusion mullite. It is possible to obtain penetration resistance and erosion resistance close to those of the case of

<Chromia (Cr ₂ O ₃ )>
The chromia is contained in an amount of 8% by mass or more and 12% by mass or less as the chemical composition in the monolithic refractory composition. When the content of the chromia is less than 8% by mass, the erosion resistance may decrease, and when it exceeds 13% by mass, the workability may be deteriorated.
The content as the chemical composition of the chromia can be measured by the same method as the content as the chemical composition of the alumina.
As a raw material of the said chromia, it is preferable to add chromia alone, and it is more preferable to add in the state of powder. By adding the chromia in the form of powder, there is an advantage that the workability of the monolithic refractory is improved. If the chromia is contained using, for example, a chromia-containing aggregate other than the powder, the chromia may be inferior in impact resistance and permeation resistance, and may not be usable in a movable furnace.
The average particle diameter of the chromia is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 mm or less, and more preferably 1.0 μm or more and 0.1 mm or less. The measuring method of the said average particle diameter can be measured, for example using a particle size analyzer.

<Zirconia (ZrO ₂ )>
The zirconia is contained in an amount of 2% by mass or more and 4% by mass or less as the chemical composition in the monolithic refractory composition.
If the content of the zirconia is less than 2% by mass, the erosion resistance may be poor, and if it exceeds 4% by mass, the content of other components must be reduced instead of the zirconia. And permeation resistance and erosion resistance may be inferior.
The content of the zirconia as the chemical composition can be measured by the same method as the content of the alumina as the chemical composition.

As a raw material of the said zirconia, it is preferable to use at least any one of zircon and badderite, and zircon is more preferable from the point of corrosion resistance.
The zircon (ZrO ₂ · SiO ₂ ) refers to zircon ore widely produced as fine crystals in igneous rock (especially granite).
The term “baderite” refers to baderite ore containing about 95% by mass to 96% by mass of the content of zirconia.
The zircon is preferably contained in an amount of 3% by mass to 5% by mass as a raw material of the monolithic refractory composition. It is preferable to contain 2 mass% or more and 4 mass% or less as said raw material of the said monolithic fireproof composition as said badderite.

<< Other ingredients >>
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a binder, a dispersing agent, etc. are mentioned.

<<< Binder >>>
Examples of the binder include alumina cement, magnesia cement, portland cement, hydraulic alumina, aluminum oxycarboxylate, phosphate, silicate, silica sol, and phenol resin. These may be used alone or in combination of two or more. The addition amount of the binder is preferably 1% by mass to 15% by mass with respect to 100% by mass of the monolithic refractory composition.

<<<Dispersant>>
The said dispersing agent has the effect of providing fluidity | liquidity at the time of construction of a monolithic refractory. Examples of the dispersant include sodium tripolyphosphate, sodium hexametaphosphate, sodium acid hexametaphosphate, sodium ultrapolyphosphate, sodium citrate, sodium borate, sodium tartrate, carboxyl group-containing polyether, sodium polyacrylate, and polycarboxylic acid. Examples include sodium acid, sodium sulfonate and sodium lignin sulfonate. These may be used alone or in combination of two or more.

  A hardening regulator, aluminum lactate, organic fiber, metal, glass and the like may be further added to the above-described monolithic refractory composition, if necessary.

(Unshaped refractory)
The monolithic refractory of the present invention is obtained by kneading, forming, and firing the raw materials constituting the monolithic refractory composition. Moreover, when forming the said monolithic refractory in the inside of a waste incinerator, for example, each raw material which comprises the said monolithic refractory composition is knead | mixed, It pours in in the said waste incinerator, and is formed, It is formed by firing. In addition, each raw material which comprises the said monolithic refractory may be hydrolyzed and knead | mixed.
Specifically, water is added to the above-described monolithic refractory composition for construction, and the mixture is kneaded, and cast and construction is performed using a mold. At the time of pouring, it is preferable to impart vibration to achieve filling. After construction, cure and dry. The construction may be performed by direct casting into a furnace, or lining by a pre-molding method using a pre-molded article obtained by casting into a mold at another place.
Among the waste incinerators, the monolithic refractory of the present invention can be suitably used particularly for a rotary kiln furnace.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, electrofused mullite, zircon, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) The mixture was mixed to obtain an amorphous refractory composition having a chemical composition shown in Table 2.

(Example 2)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, electrofused mullite, baddelite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) The mixture was mixed to obtain an amorphous refractory composition having a chemical composition shown in Table 2.

(Example 3)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, baddelite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.), An amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Example 4)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, zircon, silica, chromia, and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.), An amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 1)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, sintered mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 2)
Among the raw materials having the chemical compositions shown in Table 1, 80 mass% alumina aggregate, sintered mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 3)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, sintered mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 4)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, sintered mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 5)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, sintered mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 6)
Among the raw materials of the chemical composition shown in Table 1, 99% by mass of alumina aggregate, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.), Table 2 An amorphous refractory composition of the chemical composition shown in

(Comparative example 7)
Among the raw materials of the chemical composition shown in Table 1, 99 mass% alumina aggregate, electrofused mullite, silica, chromia and other raw materials (binder, dispersant) are mixed using a mixer (manufactured by Yotai Co., Ltd.) Then, an amorphous refractory composition having a chemical composition shown in Table 2 was obtained.

(Comparative example 8)
Among the raw materials of the chemical composition shown in Table 1, fused alumina, synthetic zirconia and chromia were mixed using a mixer (manufactured by Yotai Co., Ltd.) to obtain an indeterminate refractory composition of the chemical composition shown in Table 2. .

(Comparative example 9)
Among the raw materials of the chemical composition shown in Table 1, fused alumina, synthetic zirconia and chromia were mixed using a mixer (manufactured by Yotai Co., Ltd.) to obtain an indeterminate refractory composition of the chemical composition shown in Table 2. .

<Method of measuring chemical composition of unshaped refractory composition>
As a method of measuring the chemical composition of the indeterminate shaped refractory compositions of Examples 1 to 4 and Comparative Examples 1 to 9, a fluorescent X-ray analyzer Supermini 200 (manufactured by Rigaku Corporation) was used.

(Rotation test)
Each of the monolithic refractory compositions of Examples 1 to 4 and Comparative Examples 1 to 9 is kneaded with water, molded as a 28 mm × 230 mm, 50 mm thick molded body, aged for 24 hours, and dried at 110 ° C. It dried for 24 hours and produced the monolithic refractory. The prepared monolithic refractories were laminated to prepare a mini rotary kiln furnace. The waste cinders of the composition shown in Table 3 below are put into a scoop (approximately 100 g to 200 g) every one hour in the mini rotary kiln furnace, and actually rotated for 20 hours at 1,600 ° C. went. The melted thickness and the infiltrated thickness of the monolithic refractory were evaluated as follows. The results are shown in Table 4.

<Method of measuring dissolution and penetration>
The method for measuring the erosion of an indeterminate refractory made of the indeterminate refractory composition of Examples 1 to 4 and Comparative Examples 1 to 9 is to cut the indeterminate refractory at three points, and to measure the thickness of each cut surface The scale was used to visually measure how much the value of 50 mm decreased from 50 mm, and the average value was determined.
In the method of measuring the penetration of the monolithic refractories made of the monolithic refractory composition of Examples 1 to 4 and Comparative Examples 1 to 9, water is applied to the cut surface of the monolithic refractory and the water is elastic from the molten surface The distance to the part to which it does not penetrate, but to soak in was measured and calculated with the scale.

  As shown in Table 4, as for the monolithic refractories which consist of a monolithic refractory composition of Examples 1-4 after construction, in any case, the erosion is 3.1 mm to 3.2 mm, and the penetration is 9.6 mm to 13.1 mm. Within the range of Although Example 3 which does not use electrofusion mullite is a little weak to penetration than Examples 1-2, and 4, there is no problem at the time of practical use, and the result which can obtain the penetration resistance effect similar to the case where electrofusion mullite is used The result was that both were sufficiently resistant to dissolution. That is, it was found that the monolithic refractories made of the monolithic refractory composition of Examples 1 to 4 were all able to obtain penetration resistance and excellent erosion resistance.

  On the other hand, as shown in Table 4, the monolithic refractories made of the monolithic refractory composition of Comparative Examples 1 to 9 after construction all have a melting loss of 4.0 mm to 36.0 mm and a penetration of 0.1 mm to 15 It disperse | distributed to .8 mm, and it was a result that all were weak to melting loss compared with Examples 1-4. Further, as shown in Comparative Example 6, even if alumina having a high eutectic point was increased, sufficient erosion resistance could not be obtained, and it was rather weak to permeation. In addition, although there was no problem in the erosion resistance even if the chromia content was changed, there was a problem in the workability. None of the comparative examples was excellent in both the corrosion resistance and the permeation resistance.

(Actual furnace test)
Water is kneaded with the unshaped refractory composition of Examples 1 to 4 and Comparative Example 2 and divided into a molded body having a thickness of 280 mm on the inner wall of the outlet 8 m of a rotary kiln furnace and then sintered (taken over 10 hours The temperature was raised to 200 ° C., kept warm for 12 hours, then raised to 300 ° C. for 18 hours, kept warm for 10 hours, further raised to 600 ° C. for 10 hours, kept warm for 8 hours) The installation was performed by forming an indeterminate refractory on the inner wall of the rotary kiln furnace. Wastes of the composition shown in Table 5 below are averaged and introduced into the rotary kiln at a pace of 16.4 tons per hour, and the atmosphere temperature near the kiln outlet is controlled at about 900 ° C. to 1,200 ° C. The test was conducted while actually operating for 98.6 days. After boring a part of the monolithic refractory, in the same manner as described above, the melted thickness and the infiltrated thickness were evaluated at a distance of 13 m from the inlet of the rotary kiln. The results are shown in Table 7.

  As shown in Table 6, in comparison with the monolithic refractory consisting of the monolithic refractory composition of Comparative Example 2 after construction, the monolithic refractory consisting of the monolithic refractory composition of Examples 1 to 4 after construction is more It is clear that the resistance to melting is clearly high.

Claims (7)

An indefinitely shaped fire resistant composition containing 78% by mass to 83% by mass of alumina, 3% to 7% by mass of silica, 8% to 12% by mass of chromia and 2% to 4% by mass of zirconia in chemical composition A composition,
A monolithic refractory composition comprising, as the alumina, alumina particles having an alumina content of 99% by mass or more.   The monolithic refractory composition according to claim 1, wherein the zirconia raw material is zircon.   The monolithic refractory composition according to any one of claims 1 to 2, wherein the raw material of the alumina and the silica is electrofused mullite.   The monolithic refractory composition according to claim 3, wherein the addition amount of the electrofused mullite is 1% by mass or more and 29% by mass or less.   The monolithic refractory composition according to any one of claims 1 to 4, wherein the chromia is added in the form of powder.   A monolithic refractory characterized in that the monolithic refractory composition according to any one of claims 1 to 5 is kneaded, shaped and fired.   The monolithic refractory according to claim 6, which is for a waste incinerator.