Unshaped refractory material

Abstract

In order to address the technical problem of allowing an unshaped refractory material using a spinel-containing alumina cement to provide further improved corrosion resistance and slag infiltration resistance while reducing the occurrence of crack/peeling, an unshaped refractory material is provided which comprises a refractory raw material mixture having a particle size of 8 mm or less, with the refractory raw material mixture having an alumina cement at least a part of which is a spinel-containing alumina cement, and, with respect to 100 mass % of the refractory raw material mixture, the alumina cement contains CaO in an amount of 0.5 to 2.5 mass %, and the spinel-containing alumina cement contains spinel in an amount of 3.5 to 10.5 mass %.

Claims

1. An unshaped refractory material including a refractory raw material mixture having a particle size of 8 mm or less, the refractory raw material mixture comprising: an alumina cement, at least a part of which is a spinel-containing alumina cement, wherein, with respect to 100 mass % of the refractory raw material mixture, the alumina cement contains CaO in an amount of 0.5 to 2.5 mass %, and the spinel-containing alumina cement contains spinel in an amount of 3.5 to 10.5 mass %; and a spinel raw material having a particle size of 0.1 mm or less, wherein, with respect to 100% mass of the refractory raw material mixture, a total content of the spinal raw material and the spinel contained in the spinel-containing alumina cement is in a range of 5.5 to 22 mass %.

2. The unshaped refractory material of claim 1, wherein the refractory raw material mixture further comprises calcined alumina having a particle size of 3 m or less, wherein, with respect to 100 mass % of the refractory raw material mixture, a content of the calcined alumina is 10 mass % or less.

3. The unshaped refractory material of claim 1, wherein the refractory raw material mixture further comprises calcined alumina having a particle size of 3 m or less, wherein, with respect to 100 mass % of the refractory raw material mixture, a content of the calcined alumina is less than 4 mass %.

4. The unshaped refractory material of claim 1, wherein the refractory raw material mixture further comprises at least one of an alumina raw material and a spinel raw material, each having a particle size of greater than 0.1 mm to 8 mm, wherein, with respect to 100 mass % of the refractory raw material mixture, a total content of the at least one alumina raw material and the spinel raw material is in a range of 50 to 75 mass %.

5. The unshaped refractory material of claim 2, wherein the refractory raw material mixture further comprises at least one of an alumina raw material and a spinel raw material, each having a particle size of greater than 0.1 mm to 8 mm, wherein, with respect to 100 mass % of the refractory raw material mixture, a total content of the at least one alumina raw material and the spinel raw material is in a range of 50 to 75 mass %.

6. The unshaped refractory material of claim 3, wherein the refractory raw material mixture further comprises at least one of an alumina raw material and a spinel raw material, each having a particle size of greater than 0.1 mm to 8 mm, wherein, with respect to 100 mass % of the refractory raw material mixture, a total content of the at least one alumina raw material and the spinel raw material is in a range of 50 to 75 mass %.

7. An unshaped refractory material including a refractory raw material mixture having a particle size of 8 mm or less, the refractory raw material mixture comprising: an alumina cement, at least a part of which is a spinel-containing alumina cement, wherein, with respect to 100 mass % of the refractory raw material mixture, the alumina cement contains CaO in an amount of 0.5 to 2.5 mass %, and the spinel-containing alumina cement contains spinel in an amount of 3.5 to 10.5 mass %; and a magnesia raw material having a particle size of 0.1 mm or less, wherein, with respect to 100 mass % of the refractory raw material mixture, a content of the magnesia raw material is in a range of 2 to 9 mass %.

8. The unshaped refractory material of claim 7, wherein the refractory raw material mixture further comprises calcined alumina having a particle size of 3 m or less, wherein, with respect to 100 mass % of the refractory raw material mixture, a content of the calcined alumina is 10 mass % or less.

9. The unshaped refractory material of claim 7, wherein the refractory raw material mixture further comprises calcined alumina having a particle size of 3 m or less, wherein, with respect to 100 mass % of the refractory raw material mixture, a content of the calcined alumina is less than 4 mass %.

10. The unshaped refractory material of claim 7, wherein the refractory raw material mixture further comprises at least one of an alumina raw material and a spinel raw material, each having a particle size of greater than 0.1 mm to 8 mm, wherein, with respect to 100 mass % of the refractory raw material mixture, a total content of the at least one alumina raw material and the spinel raw material is in a range of 50 to 75 mass %.

Description

(1) Examples of refractory raw materials suitably usable in the unshaped refractory material of the present invention will be described below.

(2) As the alumina raw material, it is possible to use a raw material produced by a fusion process or a sintering process and then subjected to grading (size adjustment), or a raw material produced by a Bayer process, called calcined alumina. The alumina raw material produced by a fusion process or a sintering process and then subjected to grading may be a type containing Al.sub.2O.sub.3 in an amount of 90 mass % or more, preferably 99 mass % or more. The calcined alumina is also referred to as reactive alumina.

(3) As the spinel raw material, it is possible to use a raw material produced by a fusion process or a sintering process and then subjected to grading, as an MgOAl.sub.2O.sub.2 based compound, more specifically, a compound having a stoichiometric composition of MgO.Al.sub.2O.sub.3, or a compound having a non-stoichiometric composition, in which MgO or Al.sub.2O.sub.3 is excessively incorporated as a solid solution.

(4) As the magnesia raw material, it is possible to use a raw material produced by a fusion process or a sintering process and then subjected to grading. With a view to preventing the occurrence of crack due to volume expansion caused by slaking of the magnesia raw material during drying, it is desirable to use a magnesia raw material having high slaking resistance. Examples of the magnesia raw material having high slaking resistance include: a type containing, as impurities, CaO and SiO.sub.2, wherein a ratio CaO/SiO.sub.2 is relatively low; a type having no fracture surface; and a type subjected to surface coating.

(5) During steelmaking process, the magnesia raw material reacts with the alumina raw material to form spinel. Thus, when a finer magnesia raw material is used, spinel is more finely formed to provide more improved corrosion resistance and slag infiltration resistance, and, on the other hand, when a coarser magnesia raw material is used, a speed of formation of spinel exhibiting volume expansion is reduced, and a refractory construction formed of the unshaped refractory material exhibits a sustained residual expansion characteristic to suppress the occurrence of crack.

(6) The silica flour is a non-crystalline SiO.sub.2-based raw material having a particle size of 1 m or less, so-called silica fume, fumed silica, microsilica, volatile silica or silica dust, and is produced through in-air oxidation of SiO gas generated during production of Si, FeSi, ZrO.sub.2 or the like. Preferably, in the alumina-spinel-magnesia based unshaped refractory material, the silica flour is contained in an amount of 2 mass % or less, with respect to 100 mass % of the refractory raw material mixture having a particle size of 8 mm or less, with a view to: preventing slaking of the magnesia raw material; reducing expansion along with formation of spinel; and giving a creep property to a refractory instruction formed thereof.

(7) As the refractory material for the unshaped refractory material of the present invention, it is possible to use a raw material obtained by reusing a used refractory brick or unshaped refractory material, so-called recycle raw material. As this recycle raw material, it is desirable to reuse a used alumina-spinel based, alumina-magnesia based, or alumina-spinel-magnesia based refractory brick or unshaped refractory material.

(8) In the unshaped refractory material of the present invention, with a view to preventing extension of crack to reduce the occurrence of crack/peeling, or improving corrosion resistance based on dense and large aggregates, a refractory raw material having a particle size of greater than 8 mm may also be used. However, in the present invention, each of the CaO content, the spinel content and others is defined as a percentage with respect to 100 mass % of the refractory raw material mixture having a particle size of 8 mm or less, for the aforementioned reason.

(9) In the unshaped refractory material of the present invention, as other refractory raw materials, it is possible to use zirconia, mullite, zirconia-alumina, chromia, or the like. In this case, it is desirable to use these refractory raw materials in an amount of 10 mass % or less, with respect to 100 mass % of the refractory raw material mixture having a particle size of 8 mm or less.

(10) The unshaped refractory material of the present invention described above is suitably usable in a casting installation process or a wet-spraying installation process.

EXAMPLES

(11) Table 1 presents respective raw material compositions of Inventive Examples 1 to 21 and Comparative Examples 1 to 5. Table 2 presents respective raw material compositions of Inventive Examples 22 to 40 and Comparative Examples 6 to 9.

(12) TABLE-US-00001 Inventive Example 1 2 3 4 5 6 7 8 8 9 10 11 12 13 Refractory Sintered alumina 8-0.1 mm 52.9 53.9 54.9 54.9 54.9 56.9 57.9 56.9 54.9 52.9 50.9 49.9 64.9 64.9 Raw Sintered spinel 8-0.1 mm Material Sintered alumina 0.1 mm 9 7 7 5 5 5 12 12 5 5 7 7 10.5 15 or less Calcined alumina A 7 7 7 7 5 7 8 7 5 3 2 7 7 3 Calcined alumina B 6 6 6 6 5 6 6 6 4 4 4 6 6 4 Sintered spinel 1-0.3 mm 10 10 10 10 10 10 10 10 10 10 10 10 Sintered spinel 0.1 mm 10 9 5 5 5 10 15 16 5 5 or less Sintered magnesia 5 1-0.3 mm Sintered magnesia 0.1 mm 1 2.5 or less Silica flour 0.5 0.5 Spinel-containing alumina 5 5.5 10 8 10 15 6 8 11 10 10 10 5 10 cement Spinel-free alumina 1.5 4 5 cement Sodium polyacrylate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in cement 0.5 1.0 1.0 2.0 2.5 1.5 0.6 0.8 1.1 1.0 1.0 1.0 0.5 1.0 Spinel in spinel-containing alumina 3.5 3.9 7.0 5.6 7.0 10.5 4.2 5.6 7.7 7.0 7.0 7.0 3.5 7.0 cement Spinel having particle size of 0.1 mm 13.5 12.9 12.0 10.6 12.0 10.5 4.2 5.6 17.7 22.0 23.0 12.0 8.5 7.0 or less Magnesia having particle size of 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 2.5 0.1 mm or less Calcined alumina having particle size 6.9 6.9 6.9 6.9 5.6 6.9 7.1 6.9 4.7 4.3 4.1 6.9 6.9 4.3 of 3 m or less Evaluation Depth of Wear A A A B B B B B A A B A B B Depth of slag infiltration A A A B B A B B B B B A B B Bending strength B A A A A A B A A A A A B A Thermal spalling resistance B A A A B B B A A B B A B A Comprehensive Evaluation A A.sup.+ A.sup.+ A B A B A A B B A.sup.+ B A Inventive Example Comparative Example 14 15 16 17 18 19 20 21 1 2 3 4 5 Refractory Sintered alumina 8-0.1 mm 64.9 64.9 64.9 54.9 54.9 61.9 46.9 54.9 54.9 54.9 54.9 54.9 Raw Sintered spinel 8-0.1 mm 64.9 Material Sintered alumina 0.1 mm 6 3 6 7 14 16 7 12 13 3 3 3 or less Calcined alumina A 7 6 8 4 2 7 5 7 7 7 6 9 7 Calcined alumina B 5.5 6 5 9 11 6 4 6 6 6 5 6 5 Sintered spinel 1-0.3 mm 10 10 10 10 10 10 10 10 10 Sintered spinel 0.1 mm 5 5 8 5 5 5 5 or less Sintered magnesia 1-0.3 mm Sintered magnesia 0.1 mm 6 9 10 or less Silica flour 0.5 1 1 Spinel-containing alumina 10 10 5 10 8 10 10 10 4 10 17 16 cement Spinel-free alumina 5 6 4 cement Sodium polyacrylate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in cement 1.0 1.0 0.5 1.0 0.8 1.0 1.0 1.0 1.5 0.4 2.8 1.7 2.8 Spinel in spinel-containing alumina 7.0 7.0 3.5 7.0 5.6 7.0 7.0 7.0 0.0 2.8 7.0 11.9 11.2 cement Spinel having particle size of 0.1 mm 7.0 7.0 3.5 12.0 5.6 12.0 15.0 12.0 5.0 7.8 12.0 11.9 11.2 or less Magnesia having particle size of 6.0 9.0 10.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 mm or less Calcined alumina having particle size 6.4 6.7 6.1 9.2 10.7 6.9 4.7 6.9 6.9 6.9 5.8 7.3 6.0 of 3 m or less Evaluation Depth of Wear A A A A B A A A C B C B C Depth of slag infiltration A B B A B B A A C B B C C Bending strength A A B A A A A A A C A A A Thermal spalling resistance B B B B B A B A A B A C C Comprehensive Evaluation A A B A B A A A.sup.+ C C C C C

(13) TABLE-US-00002 TABLE 2 Inventive Example 22 23 24 25 26 27 28 29 30 31 32 33 34 Refractory Fused alumina 8-0.1 mm 54.9 54.9 54.9 54.9 54.9 54.9 54.9 54.9 54.9 54.9 54.9 54.9 51.9 Raw Material Fused alumina 0.1 mm 22 14 12 9 14 14 22 23 21 9 4 14 or less Calcined alumina A 3 3 3 3 8 3 3 3 3 4 3 Calcined alumina B 3 3 3 3 3 3 3 3 3 3 3 Sintered spinel 1-0.3 mm 10 10 10 10 10 10 10 10 10 10 10 10 10 Sintered spinel 0.1 mm 5 5 5 5 5 5 10 13 13 5 or less Sintered magnesia 3 1-0.3 mm Sintered magnesia 0.1 mm or less Silica flour Spinel-containing alumina 5 10 8 10 15 8 8 6 8 10 12 15 10 cement Spinel-free alumina cement Sodium polycarboxylate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in cement 0.5 0.1 2.0 2.5 1.5 0.8 0.8 0.6 0.8 1.0 1.2 1.5 1.0 Spinel in spinel-containing alumina 3.5 7.0 5.6 7.0 10.5 5.6 5.6 4.2 5.6 7.0 8.4 10.5 7.0 cement Spinel having particle size of 0.1 mm 8.5 12.0 10.6 12.0 10.5 10.6 10.6 4.2 5.6 17.0 21.4 23.5 12.0 or less Magnesia having particle size of 0.1 mm 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 or less Calcined alumina having particle size of 2.8 3.4 3.4 3.4 3.4 1.5 0.0 3.4 3.4 3.4 3.4 3.5 3.4 3 m or less Evaluation Depth of Wear A A B B B A A B B A A B A Depth of slag infiltration B A B B A B B B B B B B A Bending strength B A A A A B B B A A A A A Thermal spalling resistance A A A A B A A A A A A B A Comprehensive Evaluation A A.sup.+ A A A A A B A A A B A.sup.+ Inventive Example Comparative Example 35 36 37 38 39 40 6 7 8 9 Refractory Fused alumina 8-0.1 mm 64.9 64.9 64.9 64.9 64.9 52.9 54.9 54.9 54.9 54.9 Raw Material Fused alumina 0.1 mm 17.5 16 12.5 12 10 12 19 20 8 or less Calcined alumina A 3 3 3 3 3 4 3 3 3 9 Calcined alumina B 3 3 3 3 3 4 3 3 3 Sintered spinel 1-0.3 mm 10 10 10 10 10 Sintered spinel 0.1 mm 5 5 5 5 5 9 or less Sintered magnesia 1-0.3 mm Sintered magnesia 0.1 mm 1 2.5 6 8 10 or less Silica flour 0.5 0.5 0.5 1 1 Spinel-containing alumina 5 10 10 8 8 8 4 10 17 cement Spinel-free alumina 4 5 6 cement Sodium polycarboxylate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 CaO in cement 0.5 1.0 1.0 0.8 0.8 2.0 1.5 0.4 2.8 1.7 Spinel in spinel-containing alumina 3.5 7.0 7.0 5.6 5.6 5.6 0.0 2.8 7.0 11.9 cement Spinel having particle size of 0.1 mm 8.5 7.0 7.0 5.6 5.6 10.6 5.0 7.8 12.0 20.9 or less Magnesia having particle size of 0.1 mm 1.0 2.5 6.0 8.0 10.0 0.0 0.0 0.0 0.0 0.0 or less Calcined alumina having particle size of 3.4 3.4 3.4 3.4 3.4 4.5 3.4 3.4 3.4 1.6 3 m or less Evaluation Depth of Wear B B A A A B C B C B Depth of slag infiltration B B A B B B C B B C Bending strength B A A B B A A C A A Thermal spalling resistance A A A A B B A A A B Comprehensive Evaluation B A A.sup.+ A B B C C C C

(14) Refractory raw materials used in the Examples were: two types of sintered aluminas having an Al.sub.2O.sub.3 purity of 99.3 to 99.7 mass % wherein one of the sintered aluminas has a particle size of 8 to 0.1 mm, and the other sintered alumina has a particle size of 0.1 mm or less; two types of fused aluminas having an Al.sub.2O.sub.3 purity of 99.2 to 99.7 mass %, wherein one of the fused aluminas has a particle size of 8 to 0.1 mm, and the other fused alumina has a particle size of 0.1 mm or less, sintered spinel containing MgO in an amount of 4 to 6 mass % and having a particle size of 8 to 0.1 mm; two types of sintered spinels containing MgO in an amount of 26 to 28 mass %, wherein one of the sintered spinels has a particle size of 1 to 0.3 mm, and the other sintered spinel has a particle size of 0.1 mm or less; calcined alumina A in which a content of a fraction having a particle size of 3 m or less is 18.2 mass %; calcined alumina B in which a content of a fraction having a particle size of 3 m or less is 93.6 mass %; two types of sintered magnesia having a MgO purity of 95.0 to 95.5 mass %, wherein one of the sintered magnesia has a particle size of 1 to 0.3 mm, and the other sintered magnesia has a particle size of 0.1 mm or less; and silica flour containing SiO2 in an amount of 98.4 mass % and having an average particle size of 0.2 m. In addition, CMA 72 and SECAR 71 produced by Kermes Inc., were employed, respectively, as a spinel-containing alumina cement and a spinel-free alumina cement which are refractory materials used in the Examples. In each of CMA72 and SECAR71, a portion of 99 mass % had a particle size of 0.1 mm or less. Further, as a water reducing agent, sodium polyacrylate or sodium polyauboxylate was used in an amount of 0.1 mass %. A total amount of the above refractory raw materials including the water reducing agent (refractory raw material mixture) is 100 mass %.

(15) In Tables 1 and 2, the item CaO in cement presents a total amount of CaO contained in the spinel-containing alurnina cement (CMA72) and the spinel-free alumina cement (SECAR71), in units of mass % with respect to 100 mass % of the refractory raw material mixture. The item Spinel in spinel-containing alumina cement presents an amount of spinel contained in the spinel-containing alumina cement, in units of mass % with respect to 100 mass % of the refractory raw material mixture. The item Spinel having particle size of 0.1 mm or less presents a total content of the spinel raw material (sintered spinel) having a particle size of 0.1 mm or less and spinel contained in the spinel-containing alumina cement, in units of mass % with respect to 100 mass % of the refractory raw material mixture. The item Magnesia having particle size of 0.1 mm or less presents a content of the magnesia raw material (sintered magnesia) having a particle size of 0.1 mm or less, in units of mass % with respect to 100 mass % of the refractory raw material mixture.

(16) As used herein, the term a fraction having a particle size of 0.1 mm or less means an undersize fraction obtained using a sieve having a mesh opening of 0.100 mm.

(17) In Tables 1 and 2, the item Calcined alumina having 3 m or less presents a content of the calcined alumina having a particle size of 3 m or less, in units of mass % with respect to 100 mass % of the refractory raw material mixture. In this regard, a particle size distribution of each of the calcined alumina A and the calcined alumina B was measured using a laser diffraction/scattering particle size distribution measuring device, to obtain an amount of a fraction having a particle size of 3 m or less in each of the calcined alumina A and the calcined alumina B, and then, based this measurement result and respective usage amounts of the calcined alumina A and the calcined alumina B, a value of the content of the calcined alumina having a particle size of 3 m or less was calculated.

(18) Test pieces of unshaped refractory materials having respective raw material compositions in Tables 1 and 2 were produced, and subjected to evaluations on depth of wear, depth of slag infiltration, bending strength, and thermal spalling resistance. Specifically, each of the raw material mixtures in Tables 1 and 2 was kneaded with a given amount of water suitable for casting, and the resulting kneaded mixture was cast into a frame. Then, the cast mixture was sufficiently degassed by applying, to the frame, vibration with a vibrational acceleration of 2G for the test pieces pertaining to Table 1, and vibration with a vibrational acceleration of 4G for the test pieces pertaining to Table 2, and the degassed mixture was cured for 24 hours to obtain a corresponding one of the test pieces.

(19) As for the depth of wear, each of the test pieces pertaining to Table 1 was subjected to an in-slag rotation corrosion test at 1650 C. for 10 hours, using converter slag, and each of the test pieces pertaining to Table 2 was subjected to an in-slag rotation corrosion test at 1700 C. for 8 hours, using converter slag. As a result, when the depth of wear was 7 mm or less, in the range of greater than 7 mm to 10 mm, and greater than 10 mm, the test piece was evaluated, respectively, as A, B and C. The depth of wear is one index of corrosion resistance.

(20) As for the depth of slag infiltration, in the in-slag rotation corrosion test for measuring the depth of wear, when the depth of slag infilitration was 2 mm or less, in the range of greater than 2 mm to 4 mm, and greater than 4 mm, the test piece was evaluated, respectively, as A, B and C.

(21) As for the bending strength, each test piece having a size of 4040160 mm was cured in the above manner, and then, after removing the frame, subjected to drying at 110 C. for 24 hours, burning at 1200 C. for 3 hours, and then measurement on bending strength. When the measured value was 15 MPa or more, in the range of less than 15 MPa to 10 MPa, and 10 MPa or less, the test piece was evaluated, respectively, as A, B and C.

(22) As for thermal spalling resistance, each test piece having a size of 23011465 mm was cured in the above manner, and then, after removing the frame, subjected to drying at 110 C. for 24 hours, heat treatment at 350 C. for 6 hours. The obtained test piece was repeatedly subjected to a heating-cooling cycle, and then a crack occurrence state was observed. More specifically, an operation of heating a surface of the test piece having a size of 11465 mm for 30 minutes by using an electric furnace heated to 1400 C., and then cooling the test piece for 30 minutes was repeated 5 times. As a result, when the occurrence of crack was negligible, the test piece was evaluated as A. When a certain degree of crack occurred, the test piece was evaluated as B, and when a large crack occurred, the test piece was evaluated as C.

(23) As for the comprehensive evaluation, when all of the items depth of wear, depth of slag infiltration, bending strength and thermal spalling resistance were evaluated as A, the test piece was comprehensively evaluated as A.sup.+. Except for this case, when two or more of the items was evaluated as A and the remaining items were not evaluated as C, the test piece was comprehensibly evaluated as A. Except for the above cases, when no item was evaluated as C, the test piece was comprehensively evaluated as B, and, when at least one item was evaluated as C, the test piece was comprehensively evaluated as C. The evaluation becomes worse in order of A.sup.+, A, B and C.

(24) In Examples 1 to 21 in Table 1 which are Inventive Examples, none of the items depth of wear, depth of slag infiltration, bending strength and thermal spalling resistance is evaluated as C. This shows that it is possible to obtain an unshaped refractory material capable of providing high corrosion resistance and slag infiltration resistance, high strength and high thermal spalling resistance.

(25) Among Inventive Examples 1 to 21, Inventive Examples 7 and 10 in which the content of spinel having a particle size of 0.1 mm or less is out of the preferred range (5.5 to 22 mass %), Inventive Examples 12 and 16 using the magnesia raw material, in which the content of magnesia having a particle size of 0.1 m or less is out of the preferred range (2 to 9 mass %), and Inventive Example 18 in which the content of calcined alumina haying a particle size of 3 m or less is out of the preferred range (10 mass % or less), tend to be inferior to the remaining Inventive Examples in terms of results of the respective evaluations, but none of the items is evaluated as C. This shows that it is possible to obtain an unshaped refractory material capable of providing high corrosion resistance and slag infiltration resistance, high strength and high thermal spalling resistance, as compared to aftermentioned Comparative Examples.

(26) In Table 1, Comparative Example 1 is an example where the spinel-containing alumina cement is not used. It has poor corrosion resistance, and large slag infiltration Comparative Example 2 is an example where each of the content of CaO in the alumina cement and the content of spinel in the spinel-containing alumina cement is below the range set forth in the appended claims. It has poor strength.

(27) Comparative Example 3 is an example where the content of CaO in the alumina cement is above the range set forth in the appended claims. It has poor corrosion resistance.

(28) Comparative Example 4 is an example where the content of spinel in the spinel-containing alumina cement is above the range set forth in the appended claims. It has large slag infiltration and poor thermal spalling resistance.

(29) Comparative Example 5 is an example where each of the content of CaO in the alumina cement and the content of spinel in the spinel-containing alumina cement is above the range set forth in the appended claims. It has poor corrosion resistance, large slag infiltration, and poor thermal spalling resistance.

(30) Inventive Examples and Comparative Examples in Table 2 are examples where, by using a high-performance water reducing agent and molding an unshaped refractory material while applying vibration having vibrational acceleration of 4G, a dense refractory construction is produced through kneading of the unshaped refractory material with a relatively small amount of water.

(31) In Examples 22 to 40 which are Inventive Examples, none of the items depth of wear, depth of slag infiltration, bending strength and thermal spalling resistance is evaluated as C. This shows that it is possible to obtain an unshaped refractory material capable of providing high corrosion resistance and slag infiltration resistance, high strength and high thermal spalling resistance. Among inventive Examples 22 to 40, Inventive Examples 29 and 33 in which the content of spinel having a particle size of 0.1 mm or less is out of the preferred range (5.5 to 22 mass %), Inventive Examples 35 and 39 using the magnesia raw material, in which the content of magnesia having a particle size of 0.1 mm or less is out of the preferred range (2 to 9 mass %), and Inventive Example 40 in which the content of calcined alumina having a particle size of 3 m or less is out of the preferred range (4 mass % or less), tend to be inferior to the remaining Inventive Examples in terms of results of the respective evaluations, but none of the items is evaluated as C. This shows that it is possible to obtain an unshaped refractory material capable of providing high corrosion resistance and slag infiltration resistance, high strength and high thermal spalling resistance, as compared to Comparative Examples.

(32) In Table 2, Comparative Example 6 is an example where the spinel-containing alumina cement is not used. It has poor corrosion resistance, and large slag infiltration.

(33) Comparative Example 7 is an example where each of the content of CaO in the alumina cement and the content of spinel in the spinel-containing alumina cement is below the range set forth in the appended claims. It has poor strength.

(34) Comparative Example 8 is an example where the content of CaO in the alumina cement is above the range set forth in the appended claims. It has poor corrosion resistance.

(35) Comparative Example 9 is an example where the content of spinel in the spinel-containing alumina cement is above the range set forth in the appended claims, it has large slag infiltration.