KR20190064177A - Refractory composition and refractory using the same - Google Patents

Abstract

The present invention relates to a refractory composition and a refractory material using the same. An embodiment of the present invention provides a refractory composition which comprises: a raw material containing 90-95 wt% of a chromium oxide particle having the chromium oxide content of 50% or higher in performing a chemical analysis measurement; a raw material containing 1-5 wt% of a chromium oxide particle; and a raw material containing 1-5 wt% of a calcinated alumina particle with respect to 100 wt% of the entire refractory composition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory composition,

One embodiment of the present invention relates to a refractory composition and a refractory material using the refractory composition.

Refractories containing fused or sintered chromia, such as calcined chromium nitride refractories, are advantageously applied in applications such as coal gas generators and incinerators where cohesion resistance and fluid slag are important. The refractory has a high bulk specific gravity and shows high strength characteristics at room temperature. However, the strength characteristic in hot weather is low, and a refractory having high strength characteristics in hot weather is required.

On the other hand, even in the case of a refractory having a high chromium oxide content, it shows a relatively low strength at a high temperature. At this time, the more the content of the melted chromia is, the more the strength tends to be lowered. This is because the bonding force between the chromium oxide and the fused chromia particles in powder form is reduced. Therefore, it is tried to improve the bonding force between the chromium oxide and the fused chromia particles as the firing temperature increases. However, when the firing temperature is higher than the firing temperature, there is a limit to improve the refractory performance due to the vaporization of chromium.

In addition, the particle size distribution of the raw material can be controlled to reduce the breathability of the refractory material. However, since chromium oxide has a limited number of commercially available particles, there is a limit in controlling the size distribution of the particles.

On the other hand, the molding pressure can be increased to improve the density of the calcined chrome refractory material. In this case, it is helpful to improve the physical properties of the refractory material. However, refractory materials with a high content of chromium chloride may cause cracks in the molding process, which can be a very sensitive problem.

In one embodiment of the present invention, there is provided a refractory composition using chromium oxide, molten chromia, and calcined alumina as raw materials to solve the above problems.

By using a raw material containing calcined alumina, high strength properties in hot can be given. In addition, it is intended to provide a refractory material having low air permeability and difficult to penetrate slag.

A refractory composition according to an embodiment of the present invention has a chromium oxide content of 50% or more as measured by chemical analysis, a raw material containing 90 to 95% by weight of melted chromia particles, a raw material containing 1 to 5 wt% % Of chromium oxide particles, and 1 to 5% by weight of calcined alumina particles.

The maximum particle diameter of the raw material including the calcined alumina particles may be 0.075 mm or less.

The maximum particle diameter of the raw material containing the chromium oxide particles may be 0.075 mm or less.

The maximum particle diameter of the raw material containing the melted chromia particles may be 5 mm or less. Specifically, the raw material containing the melted chromia particles may include coarse particles having a particle size of more than 3 mm and not more than 5 mm, medium particles having a particle diameter of more than 1 mm and less than 3 mm, and fine particles having a diameter of not more than 1 mm.

In 100% by weight of the total composition, the proportion of coarse and medium particles of the molten chromia raw material may be 50 to 60% by weight.

In 100% by weight of the total composition, the proportion of the fine particles of the molten chromia raw material may be 30 to 45% by weight.

The raw material having a chromium oxide content of 50% or more as measured by the chemical analysis and containing 90 to 95% by weight of the chromium oxide particles has a chromium oxide (Cr ₂ O ₃ ) content of 50% or more as measured by chemical analysis, It may contain less than 8% alumina as determined by chemical analysis.

And 1 to 5 parts by weight of a binder may be further added to 100 parts by weight of the refractory composition. The binder may include AlPO ₄ , POLYAMINC WATER, P ₂ O ₃ (phosphoric acid), or a combination thereof.

Further, in another embodiment of the present invention, a refractory material containing the above-described refractory composition can be provided.

According to one embodiment of the present invention, it is possible to provide a refractory composition using raw materials including melted chromia, chromium oxide, and calcined alumina.

Concretely, by adding the raw material containing calcined alumina to the total refractory composition in an amount of 5% by weight or less, it is possible to obtain an effect of improving the hot strength and decreasing the ventilation rate. Accordingly, when the refractory composition according to one embodiment of the present invention is fired to produce a refractory material, the slag penetration area can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

The refractory composition of one embodiment of the present invention generally relates to refractory compositions based on chromia. More specifically, it relates to a chromia-based refractory composition having a chromium oxide (Cr ₂ O ₃ ) content of at least 50% by weight as measured by chemical analysis.

Specifically, the refractory composition according to an embodiment of the present invention has a chromium oxide content of 50% or more as measured by chemical analysis, a raw material containing 90 to 95% by weight of molten chromia, A raw material containing 5 wt% of chromium oxide particles, and a raw material containing 1 to 5 wt% of calcined alumina particles.

First, the reasons for limiting the composition and composition of the refractory composition raw material will be described.

In the present specification, a raw material containing melted chromia means a raw material containing chromium oxide and alumina. Specifically, the molten chromia means a product obtained by heating and dissolving a raw material containing chromium oxide and alumina, followed by hardening of the dissolved material.

In addition, the term chromium oxide (chromium oxide) and chromia in this specification refers to chromium oxide represented by the formula Cr ₂ O ₃ .

In addition, the chromium oxide means chromium oxide having a content of chromium oxide (Cr ₂ O ₃ ) of 90% or more as measured by chemical analysis.

More specifically, the raw material containing 90 to 95% by weight of molten chromia comprises at least 50% of chromium oxide, as determined by chemical analysis. More specifically, it comprises 75 to 95 wt% chromium oxide.

Further, when the raw material containing the melted chromia is measured by chemical analysis, it contains not more than 8% of alumina. Specifically, it may contain not more than 5% of alumina.

The content of the raw material including the melted chromia may be 90 to 95% by weight based on 100% by weight of the whole refractory composition.

By including the molten chromia in the above range, the volume fraction of the refractory can be improved. Accordingly, the strength characteristics at room temperature can be excellent. However, if the content of molten chromia is too large, cracking may occur in the molding process using the refractory composition. Specifically, when the amount of the melted chromia is too small, the thermal shock resistance according to the temperature change and the erosion resistance against the slag may be lowered.

The content of the chromium oxide-containing raw material may be 1 to 5% by weight based on 100% by weight of the total of the refractory composition.

By including chromium oxide in the above range, the strength in hot can be excellent. Concretely, when the content of chromium oxide is too small, the effect of improving the hot strength may be insufficient. On the other hand, if the content of chromium oxide is too large, cracking may occur after sintering due to excessive sintering reaction. As a result, the thermal shock resistance can be lowered.

In the present specification, calcined alumina refers to a raw material produced by calcination of aluminum hydroxide at 1,100 to 1,200 ° C. Specifically, the calcined alumina contains at least 80% alumina as measured by chemical analysis.

Specifically, the content of the raw material including the calcined alumina particles may be 1 to 5% by weight based on 100% by weight of the entire refractory composition.

By including the raw material containing the calcined alumina particles within the above range, the bonding force between the melted chromia and the chromium oxide can be improved in the hot state. However, when the content of calcined alumina is too small, the bonding strength in the hot state is small, and the effect of improving the hot strength may be insufficient. On the other hand, if the content of calcined alumina is too high, cracking may occur due to excessive expansion due to excessive sintering at a high temperature during sintering of the refractory composition.

Further, the physical properties of the refractory material can be determined according to the particle size of the refractory composition raw material.

Specifically, the particle size of the refractory composition raw material is as follows.

The maximum particle diameter of the melted chromia may be 5 mm or less.

Specifically, the molten chromia may include coarse particles having a particle size of more than 3 mm and a particle diameter of not more than 5 mm, a medium particle having a particle diameter of more than 1 mm and a particle diameter of not more than 3 mm, and a fine particle having a particle diameter of not more than 1 mm.

The maximum particle diameter of the chromium oxide may be 0.075 mm or less.

The maximum particle diameter of the calcined alumina may be 0.075 mm or less.

In the present specification, particle diameter means an average diameter of spherical substances present in a measurement unit. If the material is an acetal, it means the diameter of the sphere calculated by approximating the spherical material to the spherical shape.

Specifically, when the particle diameter of the raw material of the refractory composition is in the above range, it is possible to produce a refractory material having a high density when the refractory material is produced.

More specifically, the raw material including the fine particles of the raw material containing the melted chromia, the raw material including the chromium oxide particles, and the calcined alumina particles can be formed as a matrix of the refractory material thereafter. On the other hand, the coarse particles and the intermediate particles of the raw material containing the melted chromia can form a part of the refractory material having high density and low porosity.

Thus, when the refractory composition containing the raw material of the above-mentioned particle size is used, a refractory material having a high density can be produced. Accordingly, the refractory composition according to one embodiment of the present invention can be used to produce a refractory material used in a liquid slag environment.

More specifically, at 100% by weight of the total composition, the proportion of coarse and medium particles of the molten chromia feedstock may be 50 to 60% by weight.

In 100% by weight of the total composition, the proportion of the fine particles of the molten chromia raw material may be 30 to 45% by weight.

Specifically, when the ratio of the particles according to the particle diameter is in the above range, the refractory material after firing has an effect of improving the strength characteristics by improving the hot sinterability according to the closest packing.

And 1 to 5 parts by weight of a binder may be further added to 100 parts by weight of the refractory composition. Specifically, the binder may include AlPO ₄ , a polyamine compound (POLYAMINC WATER), P ₂ O ₃ (phosphoric acid), or a combination thereof.

Specifically, a refractory composition having a point-like force can be obtained by adding the above-mentioned binder to the above-mentioned refractory composition raw material. From this, by inducing reaction sintering between chromia as a neutral quality raw material, chromium oxide, and calcined alumina, it is possible to expect a more excellent strength improvement effect in the hot state.

Further, in another embodiment of the present invention, a refractory material containing the above-described refractory composition can be provided.

Hereinafter, the embodiment will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

Manufacturing example  One

The refractory compositions disclosed in Table 1 below were prepared. Specifically, 2.5 parts by weight of a binder was further added to 100 parts by weight of the refractory composition. At this time, AlPO ₄ was used as a binder. The mixing ratios according to the particle diameters of the raw materials are also shown in Table 1 below.

Then, to a refractory composition set forth in Table 1 2.0MPa / cm ³ Lt; / RTI > Thereafter, it was fired at 1,735 캜.

ingredient Particle size Comparative Example 1
(weight%) Comparative Example 2
(weight%) Example 1
(weight%) Example 2
(weight%) Molten chromia raw material 5-3mm 18 18 18 18 3-1 mm 38 38 38 38 1mm-0.075mm 19 19 19 17 0.075mm or less 15 15 15 20 Calcined alumina raw material 0.075mm or less 8 6 5 2 Chromium oxide raw material 0.075mm or less 2 4 5 5

As shown in Table 1, Comparative Examples 1, 2, and Example 1 were formulated with different contents of calcined alumina and chromium oxide.

As a result, when the refractory composition according to Comparative Examples 1 and 2 was fired, cracks appeared. This is the result of excessive sintering at high temperature calcination and cracking due to volume expansion of calcined alumina.

Manufacturing example  2

The refractory compositions disclosed in Table 2 below were prepared. Specifically, 2.5 parts by weight of a binder was further added to 100 parts by weight of the refractory composition. At this time, AlPO ₄ was used as a binder. The mixing ratios according to the particle diameters of the raw materials are also shown in Table 2 below.

Then, the refractory composition disclosed in Table 2 was molded at 2.0 MPa / cm < ^{3 &} gt ;. Thereafter, it was fired at 1,735 캜.

ingredient Particle size Comparative Example 3
(weight%) Example 1
(weight%) Molten chromia raw material 5-3mm 18 18 3-1 mm 38 38 1mm-0.075mm 19 19 0.075mm or less 21 15 Calcined alumina raw material 0.075mm or less 5 Chromium oxide raw material 0.075mm or less 4 5

As shown in Table 2, the calcined alumina raw material was not added to Comparative Example 3 in comparison with the Example 1.

As a result, the physical properties of the refractory material prepared by firing the refractory composition according to Comparative Example 3 and Example 1 are shown in Table 3 below.

Specifically, specific gravity, porosity, compressive strength, cold bending strength, hot (1400 ° C) bending strength and air permeability of the refractory were measured.

Specifically, the specific gravity and porosity of the refractory material were measured according to KS L ISO 5017.

The compressive strength of the refractory material was measured according to KS L ISO 10059-2.

Air permeability was measured according to KS L 3317.

The cold bending strength was measured according to KS L 3110 and the hot bending strength was measured according to KS L 3139.

division Comparative Example 3 Example 1 ingredient(%) Cr ₂ O ₃ 95.1 93.2 Al ₂ O ₃ 0.4 5.4 SiO ₂ 0.5 0.01 MgO 0.1 0.12 Fe ₂ O ₃ 0.1 0.5 CaO 0.2 0.07 Bulk density 3.97 4.44 Porosity (Apparent porosity,%) 19.0 12.3 Compressive strength
(cold compressive strength, Kg / Cm 3) 800 1270 Room temperature bending strength
(modulus of rupture, Kg / Cm 3) 303 146 The hot bending strength (at 1400 ° C,
hot modulus of rupture, Kg / Cm ³ ) 42 90 Percentage (centedarcies,%) 30.3 14.2

As shown in Table 3, the volume specific gravity of Example 1 to which calcined alumina raw material was added was 4.44, which is larger than that of Comparative Example 3 in which calcined alumina was not added, which is 3.97.

This is a result of the fact that the hot sintering force was increased by firing in the case of Example 1 in which calcined alumina was added. From this, it can be confirmed that the porosity of Example 1 is reduced, and the compressive strength and the hot bending strength are increased.

In addition, it can be seen that the ventilation rate of Comparative Example 3 is 30.3%, whereas that of Embodiment 1 is 14.2%. From this it can be expected that Example 1 of the present invention will have a reduced penetration area for the slag.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (11)

For 100 wt% of the total refractory composition,
A raw material having a chromium oxide content of 50% or more as measured by chemical analysis, and containing 90 to 95% by weight of molten chromia particles;
A raw material comprising 1 to 5% by weight of chromium oxide particles; And
1. A refractory composition comprising a raw material comprising 1 to 5 wt% of calcined alumina particles.
The method of claim 1,
Wherein the maximum particle diameter of the raw material including the calcined alumina particles is 0.075 mm or less.
3. The method of claim 2,
Wherein the maximum particle diameter of the raw material containing the chromium oxide particles is 0.075 mm or less.
4. The method of claim 3,
And the maximum particle diameter of the raw material containing the melted chromia particles is 5 mm or less.
5. The method of claim 4,
The raw material containing the melted chromia particles,
Coarse particles having a particle size of more than 3 mm and not more than 5 mm,
Intermediate particles having a particle size of more than 1 mm and not more than 3 mm, and
A refractory composition comprising fine particles having a particle size of 1 mm or less.
The method of claim 5,
In 100% by weight of the total composition,
And the ratio of coarse and medium particles of the molten chromia raw material is 50 to 60 wt%.
The method of claim 6,
In 100% by weight of the total composition,
Wherein the proportion of the fine particles of the molten chromia raw material is 30 to 45 wt%.
8. The method of claim 7,
A raw material having a chromium oxide content of 50% or more as measured by the above chemical analysis and containing 90 to 95% by weight of melted chromia particles,
At least 50% chromium oxide (Cr ₂ O ₃ ), as determined by chemical analysis, and
A refractory composition comprising less than 8% alumina as determined by chemical analysis.
9. The method of claim 8,
Wherein the refractory composition further comprises 1 to 5 parts by weight of a binder in relation to 100 parts by weight of the refractory composition.
The method of claim 9,
Wherein the binder comprises AlPO ₄ , POLYAMINC WATER, P ₂ O ₃ (phosphoric acid), or a combination thereof.
A refractory comprising a refractory composition according to any one of claims 1 to 10.