JPH05254924A - Clinker consisting of chromium solid solution spinel and corundum and refractory using the same - Google Patents

Abstract

PURPOSE:To provide a clinker consisting of a chromium solid soln. spinel and corundum and a refractory using the clinker, having high erosion resistance to slag and excellent thermal shock resistance and without the sinterability being deteriorated due to the contained chromium while reducing or eliminating environmental pollution, an increase in raw material cost, etc. CONSTITUTION:This clinker contains 2-10wt.% MgO, 0.05-20wt.% Cr2O3, >=90wt.% of Cr2O3 plus alumina and <=5wt.% of impurities and has a crystal phase in which the spinel crystal of the magnesia and alumina forming a solid soln. with chromium and corundum crystal coexist.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a clinker which is a refractory material having high erosion resistance against slag generated in ironmaking, steelmaking, etc. and excellent thermal shock resistance, and a refractory obtained by using the clinker. Is.

[0002]

BACKGROUND ART As is well known, refractory materials for iron and steelmaking endure high temperatures of 1400 to 1600 ° C or more, have a small volume change, and are resistant to erosion by slag and the like. Is required to have.

[0003] In general, a basic refractory is used as one having excellent slag reactivity, and among them, a magnesia refractory having particularly high refractory properties has been preferably used. .. However, since such a magnesia refractory material has a large volume change with respect to heat, it is weak against thermal shock, and when it is brought into contact with hot metal such as hot metal or molten steel, there is a drawback that thermal spalling is likely to occur. Further, since the slag easily penetrates into the crystal grain boundaries, there is also a drawback that structural spalling easily occurs due to the difference in thermal expansion.

Therefore, in recent years, development of a refractory material capable of solving such a drawback and providing an excellent refractory material for iron making, steel making, etc. has been underway. And, as such a refractory material, attention has been paid to a magnesia alumina-based spinel clinker obtained by adding alumina to magnesia and firing it at a high temperature, and various refractories for steelmaking and steelmaking obtained using this. Has been proposed.

For example, JP-A-2-102167 discloses that MgO is 1 to 20% by weight and Al ₂ O ₃ is 80 to 99.
It has a composition containing unavoidable impurities derived from raw materials in addition to wt%, and clinker composed of magnesia alumina spinel crystal and corundum crystal is blended with spinel and alumina to obtain a refractory material. Has been done. Moreover, in Japanese Patent Laid-Open No. 3-60461, Mg is disclosed.
O: 0.5 to 8.5 _{wt%, Al 2 O 3: 90~99} .
A clinker composed of magnesia alumina spinel crystals and corundum crystals, which has a chemical composition of 45 wt% and CaO: 0.05 to 1.50 wt%, and a refractory containing the same as a refractory material have been proposed. ing. And in any of those publications, those clinker,
Since a magnesia alumina-based spinel crystal and a corundum crystal coexist, a refractory obtained using such a clinker has a small thermal expansion and is excellent in thermal shock resistance, and further against slag. It has been shown to also have high erosion resistance.

However, according to the study by the present inventors, a refractory obtained by using a clinker made of a conventional magnesia alumina spinel contains corundum crystals like the refractory disclosed in such publication. Or, even if the composition is more densified, it is clear from the chemical composition that there is a limit to the improvement of the erosion resistance against the slag whose main component is CaO that exhibits high basicity. It was

Therefore, in such refractories, there is a demand for further improvement in erosion resistance against slag, which is accompanied by severer use conditions of refractory due to development of blast furnaces and steelmaking furnaces in recent years. I couldn't answer at all.

In addition to magnesia, dichrome trioxide (Cr ₂ O ₃ ) having a high melting point (2265 ° C.) is well known as an industrial material having excellent fire resistance. Further, as the resistance of Cr ₂ O ₃ to slag, CaO and Si, which are the main components of slag, are used.
The state of the mineral phase composed of O ₂ and Cr ₂ O ₃ is shown by the relation between its composition and temperature, “Phase Diagr
ams for Ceramics "(The Am
erican Ceramic Society. In
c. Issued). 651 "CaO-Cr ₂ O ₃ -S
Phase equilibrium diagrams for "IO ₂ -based" refractories are known. In addition, there are, "CaO-Al ₂ O ₃ -SiO
₂ system ", in refractories such as" CaO-MgO-SiO ₂ system ", each of the phase diagram is also described together. The phase equilibrium diagrams are shown in FIGS. 1 to 3.

As is clear from FIGS. 1 to 3, Ca
O-SiO₂Cr for the system₂O₃Refractory using
Refractory solids at 1600 ° C, the typical operating temperature
The melted region is CaO-SiO₂Al for the system₂O₃
1/7 to 1/10 compared to refractories using MgO and MgO
It is a much smaller area. That is, Cr₂O₃Is resistant
CaO and S, which are slag components that have a large erosion effect on fire
iO₂Against Al ₂O₃And at higher temperatures than MgO
It has excellent chemical resistance.

The magnesia chrome brick having a dense structure, which is obtained by high-temperature firing using chromite ore and magnesia clinker, has been widely used as a refractory material showing high erosion resistance against slag. ing.

Therefore, from these facts, Cr ₂ O
_It is surmised that ₃ contributes to the improvement of the slag corrosion resistance of the refractory material. Therefore, it is considered that when a refractory for iron making and steel making is manufactured using such Cr ₂ O ₃ , a refractory having excellent fire resistance and high erosion resistance against slag can be obtained.

However, when a refractory material is produced by using such Cr ₂ O ₃ as a raw material, it is difficult to obtain a dense sintered body of Cr ₂ O _{3 by} a conventional method. is Cr ₂ O _3, it changes to harmful substances in which hexavalent chromium on the human body is easy, as the further industrial materials, it like according Cr ₂ O ₃ is very expensive, exists a number of problems Of. Therefore, such Cr ₂
Using O ₃ as a raw material, and the problems associated with it,
Up to now, no refractory for iron and steel making has been manufactured without causing anything.

[0013]

The present invention has been made in view of such circumstances, and the problem to be solved is obtained by coexistence of a magnesia alumina-based spinel crystal and a corundum crystal. Characteristics,
By making good use of the characteristics of chromium, while ensuring excellent thermal shock resistance, it is possible to advantageously improve the erosion resistance against slag, and further reduce the problems caused by including chromium as a raw material as much as possible. Another object of the present invention is to provide a clinker composed of chromium solid solution spinel and corundum, which is eliminated, and a refractory material obtained by using the clinker.

[0014]

Under the circumstances, the present inventors have made various studies in order to solve the above problems. Then, the above-mentioned "Phase Diagrams for Cera"
Mists' fig. 4570 "MgO-Cr ₂ O ₃
-Al ₂ O ₃ "indicates that chromium is incorporated into the crystal structure of magnesia-alumina spinel and the crystal structure of corundum by substitution of Al ³⁺ ions with Cr ³⁺ ions to form a solid solution. Focusing on this point, further intensive research was conducted in order to use such solid solutions of chromium solid solution magnesia alumina spinel and corundum as refractory materials for iron and steelmaking.

Consequently, as a result, a specific amount of a small amount of Cr ₂
A clinker consisting of O ₃ and specific amounts of MgO, Al ₂ O ₃ and inevitable impurities derived from their raw materials, and a clinker comprising magnesia alumina spinel and corundum in which chromium is solid-dissolved, and obtained by using the clinker The refractory has high thermal stability, has large crystal grains, has a dense structure due to sintering, and is a safe one in which the change of chromium to hexavalent chromium is advantageously prevented, and The present inventors have found that the slag exhibits higher erosion resistance than conventional ones.

That is, the present invention has been completed on the basis of such findings, and the features thereof are as follows.
It contains MgO in an amount of 2% by weight or more and less than 10% by weight, contains Cr ₂ O _{3 in an amount} of 0.05 to 20% by weight, and further has a total amount of Cr ₂ O ₃ and Al ₂ O ₃ of more than 90% by weight. , 98
A clinker comprising a magnesia-alumina spinel and corundum, each having a chemical composition of less than 5% by weight and having an impurity content of less than 5% by weight, and containing chromium as a solid solution.

Further, in the clinker comprising the chromium solid-solved spinel and corundum according to the present invention, it is advantageous that the apparent porosity of the clinker is 20% or less. The average crystal size of the system spinel or corundum is preferably 10 μm or more.

Further, in the present invention, MgO: 2% by weight or more and less than 10% by weight, Cr ₂ O ₃ : 0.05-2.
Magnesia-alumina system having a chemical composition of 0% by weight, the total amount of Cr ₂ O ₃ and Al ₂ O ₃ : more than 90% by weight, 98% by weight or less, and impurities: 5% by weight or less, and each containing chromium in solid solution A refractory formed by using a clinker having spinel and corundum as a refractory material and molding the clinker into a predetermined shape is also featured.

[0019]

[Specific Structure] In short, the clinker composed of the chromium solid solution spinel and corundum according to the present invention, and the refractory material obtained by using the same are the coexistence of the magnesia alumina-based spinel crystal and the corundum crystal in which chromium is dissolved. It has a crystalline phase consisting of, thereby, in erosion resistance and thermal shock resistance to slag,
It has excellent properties.

In the clinker composed of chromium solid solution spinel and corundum according to the present invention, the main component composition is Cr ₂ O ₃ , MgO and Al ₂ O _3.
The content of MgO is 2% by weight or more and less than 10% by weight, and the total content of Cr ₂ O ₃ and Al ₂ O ₃ is more than 90% by weight and 98% by weight at the same time. Must be: When the content of MgO is less than 2% by weight and the total content of Cr ₂ O ₃ and Al ₂ O ₃ exceeds 98% by weight, a magnesia alumina spinel crystal produced by MgO and Al ₂ O ₃ Are very few or are never generated. Also, Mg
When O is contained in an amount of 10% by weight or more and the total content of Cr ₂ O ₃ and Al ₂ O ₃ is 90% by weight or less, only magnesia alumina-based spinel crystals are produced and corundum crystals are formed. It will not be deposited. Therefore, in any of these cases, the crystal phase in which the magnesia alumina-based spinel crystal and the corundum crystal coexist cannot be maintained, and thus in the target clinker and refractory, the corrosion resistance to slag decreases. As a result, the problem that the thermal shock resistance against molten steel or the like cannot be expected to be further improved is caused.

The clinker according to the present invention and the refractory material obtained by the clinker are, as one of the main components,
By containing Cr ₂ O ₃ , some of the Al ³⁺ ions are replaced with Cr ³⁺ ions in the respective crystal structures of the magnesia alumina-based spinel crystal and the corundum crystal, and the slag is chemically reacted. Chromium, which has a high thermal resistance, is solid-dissolved. As a result, the erosion resistance to slag is advantageously enhanced, as a result, the formation of reaction-altered parts is reduced, the occurrence of structural spalling is suppressed, and the conversion of chromium into hexavalent chromium is suppressed. It can be effectively prevented, and the sinterability can be improved. However, in order to fully enjoy such effects, Cr ₂ O ₃ must be contained in the range of 0.05 to 20% by weight, preferably 0.05 to 10% by weight. .. When the content of Cr ₂ O ₃ is less than 0.05% by weight, it is impossible to expect effective improvement of erosion resistance to slag in the target clinker and refractory, and expensive Cr ₂ O ₃
However, if it exceeds 20% by weight, it becomes economically impractical.

In the clinker according to the present invention, Fe ₂ O ₃ , TiO ₂ , CaO, K ₂ O and Na are used.
_Although it is acceptable to include impurities such as various oxides such as ₂ O and SiO ₂ , the content of such impurities is
The total must be less than 5% by weight.

Further, the clinker made of magnesia-alumina-based spinel having a solid solution of chromium and corundum according to the present invention as described above is preferably made of particles having a dense structure with an apparent porosity of 20% or less. Further, in the magnesia-alumina-based spinel crystal and corundum crystal in which chromium is dissolved, the average crystal diameter is preferably 10 μm or more, more preferably 20 μm.
It is desirable that the above is done.
This is because the refractory obtained by using a clinker having a dense structure and having a large crystal grain size can further improve the corrosion resistance to slag.

Thus, the clinker comprising such chromium solid solution spinel and corundum can be advantageously produced by the following method.

First, the chemical composition after sintering is MgO: 2% by weight or more and less than 10% by weight, Cr ₂ O ₃ : 0.05-2.
0 wt%, Cr ₂ O ₃ and Al ₂ O ₃ total amount: more than 90 wt%, 98 wt% or less, unavoidable impurities originating from the raw materials: 5 wt% or less, respectively, MgO raw material, Al Mix ₂ O ₃ raw material and Cr ₂ O ₃ raw material.

The respective raw materials used therein are not particularly limited as long as they can give the above chemical composition after firing. That is, conventionally known as a raw material of clinker or refractory,
Any of them can be used, for example, as the MgO raw material, commercially available magnesia clinker, magnesium hydroxide and magnesium oxide obtained by heat-treating it, natural magnesite and magnesium oxide obtained by heat-treating it , Various magnesium salts, and the like, and as the Al ₂ O ₃ raw material, commercially available alumina clinker, aluminum hydroxide produced by the Bayer method, and aluminum oxide obtained by heat-treating it, natural bauxite, and a calcined product thereof. , Various aluminum salts and the like can be used. And further, Cr ₂ O
_{As the three} raw materials, dichromium trioxide, various chromium salts and the like can be used. In addition, when blending the raw materials, it is not always necessary to select and use one type from each of them, and it is possible to use two or more types of each raw material in combination.

Next, the compound thus obtained is pulverized and mixed, but in the subsequent heat treatment, it becomes easier to sinter, and the structure in the sintered body becomes homogeneous. Preferably 15
This composition is pulverized and mixed until the particle diameter becomes equal to or less than μm. Further, when the average particle size of the pulverized mixture thus obtained exceeds 50 μm, the bulk density of the clinker particles finally obtained becomes low, and the apparent porosity is 20% by firing. It is desirable that the average particle size of the pulverized mixture is set within the above range because the following sintered body may not be obtained. In this pulverization and mixing, any conventionally known device can be used, and either wet or dry method can be adopted.

Next, the pulverized mixture thus obtained is subjected to a granulation operation by a general method according to the pulverization and mixing technique to obtain a granulated product. That is, among these crushed mixtures, the slurry obtained by throwing them into a ball mill or the like together with water and crushing and mixing them by a wet method is dehydrated by a filter press or the like and then granulated into pellets by an extruder or the like. .. The dry mixture obtained by the dry pulverization and mixing method is dry granulated by a tumbling granulator or the like.

Then, after drying the granules, if necessary, chromium is added to the magnesia-alumina-based spinel crystal and the chromium in a common calcination facility such as a rotary kiln, a tunnel kiln and a shaft kiln in the air. Heat treatment to corundum crystals until a solid solution is obtained,
Obtain a sintered body. Note that this heat treatment is generally performed at 170
It is performed in a temperature range of 0 ° C to 1950 ° C. Further, in this heat treatment, it is advantageous that the granules have an average diameter of each crystal of chromium solid solution spinel and corundum of 10 or less.
It will be heated and sintered until it has a fine structure of not less than μm, more preferably not less than 20 μm and an apparent porosity of not more than 20%.

Thus, the thus obtained sintered body has a magnesia alumina spinel crystal phase and a corundum crystal phase, respectively, in which chromium is solid-solved, and thus the chromium solid solution according to the present invention is obtained. A clinker consisting of spinel and corundum is obtained. In the above, the method for producing the clinker having the characteristics of the present invention by the sintering method has been described in detail, but the present invention relates to the spinel and corundum composition of chromium solid solution, and the sintering method However, the clinker comprising the chromium solid solution spinel and corundum according to the present invention can be produced by any other production method such as an electrofusion method.

Further, to obtain the refractory material according to the present invention,
Advantageously, the following method will be followed.

First, a clinker composed of chromium solid solution spinel and corundum, which has the characteristics of the present invention, is pulverized and sized by a usual method to obtain a powder or granules of such clinker. .. Then, the obtained powder or granules are used as a refractory material, they are molded into a predetermined shape, and if necessary, heated and sintered to obtain a refractory material such as brick.

As another method, the clinker according to the present invention obtained as described above may be mixed with cement, binder or the like, if necessary, to give an amorphous refractory, and then the amorphous refractory. Some refractories are subjected to operations such as a stamp molding method and a vibration molding method, and finally, a desired refractory product is obtained by molding this into a predetermined shape.

It is most preferable that the refractory material used to obtain such a refractory material consists only of powder or granules of the clinker according to the present invention. It may be mixed and used as a mixed refractory material. At that time, as a general refractory material, if a refractory material which is cheaper than the clinker according to the present invention or a refractory material having properties not obtained by the clinker is selected and used, it can be obtained only by the clinker according to the present invention. Refractory materials that are less expensive than refractory materials and have a wide range of properties can be obtained. However,
In such a compounded refractory material, in order to obtain a refractory material having a high erosion resistance against slag, it is desirable to contain at least 5% by weight or more of the clinker powder or granules according to the present invention. ..

Examples of such general refractory materials include alumina refractory materials and spinel refractory materials. Specifically, as the alumina-based refractory material, a fired product of high-alumina rocks, a calcined product of bauxites or a fired product, diaspores, sillimanites, synthetic mullite, fused alumina, sintered alumina, activated alumina, oxidation Aluminum, band shale, etc. may be used, and as the spinel refractory material, seawater magnesia clinker, magnesite ore and its fired product, molten or sintered magnesia material, electrofused or sintered spinel clinker, etc. It can be adopted.

Further, in such a compounded refractory material,
In addition, it is acceptable to include auxiliary materials such as clay, silicon carbide, finely powdered silica, graphite and various binders. And, in particular, the binder contained as an auxiliary material may be any binder as long as it is used in a usual refractory manufacturing process. That is, hydraulic cement such as alumina cement, alkali metal salt such as sodium phosphate and sodium silicate, alkaline earth metal salt such as aluminum phosphate and magnesium sulfate, various amorphous silica, inorganic binder such as orthophosphoric acid, phenol resin and An organic binder such as a furan resin, a tar- or pitch-based carbon binder, a pulp waste liquid, a bitter juice, and the like can be allowed to be contained in the compounding material.

The refractory material thus obtained contains the clinker according to the present invention as a refractory material, and is capable of exhibiting excellent properties in heat shock resistance and slag erosion resistance for iron and steelmaking. It becomes a thing.

[0038]

EXAMPLES Hereinafter, representative examples of the present invention will be shown to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. Further, in addition to the following specific examples, in addition to the following embodiments, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention.
It should be understood that modifications, improvements, etc. may be made.

First, Al ₂ O ₃ raw material, MgO raw material, Cr
Commercially available calcined alumina, magnesium hydroxide, and dichromium trioxide were used as the ₂ O ₃ raw materials, respectively, and the theoretical chemical compositions after sintering were within the scope of the present invention. It was mixed as follows. And the obtained compound was set to Example 1, Example 2, Example 3, and Example 4, respectively. In addition, in order to clarify the effect of adding chromium, magnesium hydroxide and calcined alumina alone were mixed in different amounts without using dichromium trioxide, and the resulting mixture was prepared as Comparative Example 1 respectively. And Comparative Example 2. The theoretical chemical compositions after sintering of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1 below.
Shown in.

[0040]

[Table 1]

Next, each of the blends was placed in a ball mill, water was further added, and the mixture was ground and mixed by a wet method to obtain each sludge. Then, the sludge thus obtained was taken out from the ball mill, dehydrated by a filter press, and then granulated into pellets by an extruder. Then, the obtained granulated product is dried, and then the granulated product is subjected to 1 in a gas furnace.
Heat treatment was performed at a heating temperature of 700 ° C. to 1900 ° C. for 30 minutes to obtain heat-treated particles that were the target clinker. Then, the physical properties of the heat-treated particles for each heating temperature, that is, the apparent specific gravity, bulk specific gravity, apparent porosity, and water absorption rate were measured. The results and the constituent minerals of each heat-treated particle are shown in Table 2 below. Note that these physical properties are described in "JIS R2205
-7 Measuring method of apparent porosity, water absorption rate and specific gravity of refractory bricks ". The constituent minerals were obtained by identifying each crystal phase using an X-ray diffractometer. Table 2 below
Inside, Sp is spinel crystal, Co is corundum crystal,
Represent each.

[0042]

[Table 2]

As is clear from the results of these tables, the chemical composition after sintering is MgO: 2 wt% or more, 10 wt%
Less than, Cr ₂ O ₃ : 0.05 to 20% by weight, Cr ₂ O ₃
The sum of the Al ₂ O _3: 90 wt.%, 98 wt% or less, impurity: to be 5 wt% or less, MgO raw material,
Cr ₂ O ₃ raw material and Al ₂ O ₃ raw material are mixed,
The compound thus obtained is crushed and mixed, and the resulting mixture is granulated, and then the granulated product is
A heat-treated sintered body at 1700 ° C. to 1900 ° C., which is composed of magnesia-alumina-based spinel crystals and corundum crystals in which chromium is solid-solved and has a dense structure with an apparent porosity of 20% or less. was gotten.

Of the heat-treated particles shown in Table 2, the clinker having the characteristics of the present invention and comprising chrome solid solution spinel and corundum was used in Examples 1 to 1.
4, the heat-treated particles at 1900 ° C., and the heat-treated particles at 1900 ° C. in Comparative Examples 1 and 2, which became a clinker made of spinel and corundum in which chromium does not form a solid solution, were crushed, respectively. A crushed product was obtained. Then, the pulverized product and a sintered alumina pulverized product as a general refractory material were compounded with the compounding ratios and particle size distributions shown in Table 3 below to obtain different compounds. Of these formulations, those obtained by using Examples 1 to 4 alone are used as Examples 5 to 5.
No. 8 and the mixed refractory materials obtained by adding the sintered alumina pulverized products to Examples 1 and 4, respectively, were referred to as Examples 9 and 10, respectively. Further, those obtained by using Comparative Examples 1 and 2 alone are referred to as Comparative Examples 3 and 4, respectively, and further mixed refractory materials obtained by adding sintered alumina pulverized products to Comparative Examples 1 and 2, respectively. The materials were Comparative Examples 5 and 6, respectively.

[0045]

[Table 3]

Next, the thus-obtained blends were respectively subjected to an Amsler type pressure resistance tester to produce cylindrical shaped bodies of 50 mmφ × 50 mmH at a pressure of 1 t / cm ² . Then, for those molded bodies, 1 in a gas furnace
The heat treatment was performed at a heating temperature of 900 ° C. for 30 minutes to obtain a heat-treated body as a refractory material. Then, the apparent porosities of the heat-treated bodies as the refractory materials were measured. The results are shown in Table 4 below. The apparent porosities were measured by the same method as the method of measuring the apparent porosity of the clinker.

[0047]

[Table 4]

Further, in order to clarify the reactivity of the refractory materials with the slag, the central portion of each refractory material is
Depth: 20 mm, diameter: 10 mm, hollowed out, and each of the holes thus formed was charged with a predetermined amount of slag having the chemical composition shown in Table 5 below.
Heat treatment was performed at 600 ° C. for 2 hours. After that, the refractory is cut so as to divide the hole into which the slag has been introduced, and the reaction state between the refractory and the slag, that is, the state of crack formation due to the erosion action of the slag of the refractory and the refractory The average penetration depth of slag in the product was measured. Table 6 below shows the measurement results and the evaluation results for the reactivity with the slag, which were determined from the measurement results. In addition, in the evaluation results of Table 6, ◯ means good, Δ means good, × means bad, and Δ and × mean that the reactivity with slag is substantially poor.

[0049]

[Table 5]

[0050]

[Table 6]

As is clear from the results of these tables, Mg
Contains O in an amount of 2% by weight or more and less than 10% by weight, Cr ₂ O ₃
Is contained in an amount of 0.05 to 10% by weight, Cr ₂ O ₃ and Al ₂
The sum of the O _3: 90 wt.%, Is 98 wt% or less,
Further, a refractory having a chemical composition in which the unavoidable impurities derived from the raw material is 5% by weight or less, and containing as a refractory material a clinker composed of spinel and corundum in which chromium is solid-solved, respectively No occurrence has been seen. Further, such a refractory material according to the present invention has an average penetration depth of slag of about 1/2 as compared with a refractory material containing a clinker made of spinel and corundum in which chromium does not form a solid solution as a refractory material.
It is only a moderate value. As shown in the evaluation results in Table 6, the refractory containing a clinker made of chromium solid-solution spinel and corundum as a refractory material according to the present invention has a higher refractory content than chromium does not form a solid solution.
The result proves that it exhibits excellent characteristics in reactivity with slag, that is, in erosion resistance against slag.

[0052]

As is apparent from the above description, the clinker composed of the chromium solid solution spinel and corundum according to the present invention has chromium having a large chemical resistance to slag dissolved in each crystal structure, Since a magnesia alumina spinel crystal and corundum crystal coexist, in a refractory obtained using such a clinker, erosion resistance to slag is higher than that of the conventional one. It was markedly increased. Further, such a refractory material also has excellent properties in thermal shock resistance.

Further, in the clinker according to the present invention and the refractory material obtained by using the clinker, since chromium is used as a solid solution in its crystal structure, it is harmful to the human body. The change to hexavalent chromium can be effectively prevented, the safety for use of chromium can be ensured, and the sintering by the normal operation can be easily performed. Moreover, in such clinker and refractory, the content of chromium dissolved in the crystal structure of the clinker is as small as possible, so that the raw material cost may increase due to the use of expensive chromium. , Can be advantageously suppressed.

Further, the clinker according to the present invention is made to have a dense structure having an average crystal diameter of 10 μm or more and an apparent porosity of 20% or less, so that a refractory material obtained by using such a clinker The erosion resistance of the slag will be further improved.

[Brief description of drawings]

FIG. 1 is a phase equilibrium diagram of a CaO—Cr ₂ O ₃ —SiO ₂ system refractory material.

FIG. 2 is a phase equilibrium diagram of a CaO—Al ₂ O ₃ —SiO ₂ -based refractory material.

FIG. 3 is a phase equilibrium diagram of a CaO—MgO—SiO ₂ system refractory material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimito Nakamoto 11-4, Shiogusa-cho, Seto-shi, Aichi Uchigai Ceramix Co., Ltd. (72) Inventor Eiichi Kamiya 4-4, 11-shiogusa-cho, Seto-shi, Aichi Naigai Cera Mix Co., Ltd.

Claims (4)

[Claims] 1. A MgO: 2 wt% or more and less than 10 wt%, Cr ₂ O _3: 0.05~20 wt%, the total amount of Cr ₂ O ₃ and Al ₂ O _3: 90 wt.%, 98 wt %Less than,
Impurity: A clinker comprising chromium solid solution spinel and corundum, which has a chemical composition of 5% by weight or less and is composed of magnesia alumina spinel and corundum in which chromium is solidly dissolved. 2. The apparent porosity is 20% or less.
A clinker comprising the solid solution spinel of chromium and corundum described in 1. 3. A clinker comprising a chromium solid solution spinel and corundum according to claim 1 or 2, wherein the magnesia alumina spinel or corundum in which chromium is solidly dissolved has an average crystal diameter of 10 μm or more. 4. MgO: 2 wt% or more and less than 10 wt%, Cr ₂ O _3: 0.05~20 wt%, the total amount of Cr ₂ O ₃ and Al ₂ O _3: 90 wt.%, 98 wt %Less than,
Impurity: A refractory material having a chemical composition of not more than 5% by weight and using as a refractory material a clinker having a magnesia alumina spinel and corundum in which chromium is solid-dissolved.