SMELTING LADLE AND METHOD FOR IMPROVING USE EFFICIENCY THEREOF

Abstract

A smelting ladle includes a housing, a circulating working layer, a consumable working layer, and a permanent layer. The permanent layer is masoned or casted on an inner wall of the housing, the circulating working layer is casted on an inner wall of the permanent layer, and the consumable working layer is masoned on an inner wall of the circulating working layer.

Claims

1. A smelting ladle, comprising: a housing, a permanent layer, a circulating working layer, and a consumable working layer; wherein: the permanent layer is masoned or casted on an inner wall of the housing; the circulating working layer is casted on an inner wall of the permanent layer; and the consumable working layer is masoned on an inner wall of the circulating working layer.

2. The smelting ladle of claim 1, wherein the permanent layer is masoned or casted by a refractory having a bulk density of 0.3 g/cm.sup.3, a compressive strength at normal temperature of 2.0 megapascal, and a refractory temperature of 1100 C.; and a thickness of the permanent layer is 150 mm.

3. The smelting ladle of claim 2, wherein the thickness of the permanent layer is between 20 and 80 mm.

4. The smelting ladle of claim 1, wherein the circulating working layer is casted by a refractory castable having a bulk density of 2.5 g/cm.sup.3 and a refractory temperature of 1600 C.; and a thickness of the circulating working layer is between 20 and 250 mm.

5. The smelting ladle of claim 1, wherein the consumable working layer is masoned by refractory bricks having a bulk density of 2.8 g/cm.sup.3 and a refractory temperature of 1600 C.; and a thickness of the consumable working layer is between 80 and 250 mm.

6. A smelting ladle, comprising: a housing, a permanent layer, a circulating working layer, and a consumable working layer; the permanent layer comprising an inner permanent layer and an outer permanent layer; wherein: the permanent layer is masoned on an inner wall of the housing, the circulating working layer is casted on the inner wall of the permanent layer, and the consumable working layer is masoned on an inner wall of the circulating working layer; the permanent layer is formed by the inner permanent layer contacting with the circulating working layer and the outer permanent layer contacting with the housing; the inner permanent layer is masoned by a first heat insulating blocks; and the outer permanent layer is masoned by alternate arrangement of the first heat insulating blocks and a second heat insulating blocks.

7. The smelting ladle of claim 6, wherein the first heat insulating blocks of the outer permanent layer are alternately disposed in a circumferential direction to form multiple circles from top downwards along the inner wall of the housing; multiple of the second heat insulating blocks are disposed between adjacent first heat insulating blocks of a same circle; and the first heat insulating blocks of adjacent two circles are staggered.

8. The smelting ladle of claim 7, wherein: the first heat insulating blocks of the outer permanent layer are alternately disposed in the circumferential direction to form between 8 and 14 circles from top downwards along the inner wall of the housing; and between 3 and 5 second heat insulating blocks are disposed between the adjacent first heat insulating blocks of the same circle.

9. The smelting ladle of claim 6, wherein: the first heat insulating blocks of the outer permanent layer are arranged to form a network structure from the top downwards along the inner wall of the housing, and multiple of the second heat insulating block are filled in cavities of the network structure.

10. The smelting ladle of claim 9, wherein the cavities of the network structure are in a shape of a rectangle or a diamond; and between 3 and 5 second heat insulating block are filled therein.

11. The smelting ladle of claim 6, wherein: the first heat insulating blocks are heat insulating blocks having a compressive strength of between 5 and 20 megapascal, a bulk density of between 0.6 and 1.5 g/cm.sup.3, a thermal conductivity at 800 C. of between 0.20 and 0.50 W/mk; and the second heat insulating blocks are heat insulating blocks having a compressive strength of between 0.10 and 0.50 megapascal, a bulk density of between 0.2 and 0.5 g/cm.sup.3, and a thermal conductivity at 800 C. of between 0.04 and 0.15 W/mk.

12. The smelting ladle of claim 6, wherein a thickness of the inner permanent layer is between 5 and 50 mm; and a thickness of the outer permanent layer is between 5 and 30 mm.

13. A smelting ladle, comprising: a housing, a permanent layer, a circulating working layer, and a consumable working layer; wherein: the permanent layer is masoned on an inner wall of the housing, the circulating working layer is casted on the inner wall of the permanent layer, and the consumable working layer is masoned on an inner wall of the circulating working layer; a castable of the circulating working layer comprises: between 55 and 70 parts by weight of a sintered microporous corundum aggregate, between 5 and 10 parts by weight of a magnesia-alumina spinel aggregate, between 10 and 25 parts of a fine powder, between 2 and 8 parts by weight of a micro powder, between 3 and 8 parts by weight of a binder, between 0.1 and 0.5 part by weight of a detonation suppressor, between 0.05 and 2 parts by weight of a water reducing agent, and between 0.01 and 0.1 part by weight of a foaming agent; the fine powder comprises a component A and a component B; the component A is one selected from a fused white corundum and a sintered tubular corundum, and the component B is one selected from a magnesia-alumina spinel and a magnesia; and the micro powder is a mixture of a SiO.sub.2 fine powder and an active -Al.sub.2O.sub.3 fine powder or a mixture of the SiO.sub.2 fine powder and a sintered tubular corundum fine powder.

14. The smelting ladle of claim 13, wherein the sintered microporous corundum aggregate has a content of Al.sub.2O.sub.3 of 99.5 wt. %, a bulk density of between 3.0 and 3.4 g/cm.sup.3, a closed porosity of 10%, an average pore diameter inside a particle of 1.0 m, and a particle size of 25 mm.

15. The smelting ladle of claim 13, wherein: the sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm; and weight percentages thereof are correspondingly as follows: 13-17 wt. %, 28-32 wt. %, 18-22 wt. %, 18-22 wt. %, and 13-15 wt. %.

16. The smelting ladle of claim 13, wherein the magnesia-alumina spinel aggregate comprises between 10 and 40 wt. % of MgO and between 60 and 90 wt. % of Al.sub.2O.sub.3; a particle size of the magnesia-alumina spinel aggregate is 3 mm; and the magnesia is a fused magnesia comprising 97 wt. % of MgO or a sintered magnesia comprising 97 wt. % of MgO.

17. The smelting ladle of claim 13, wherein the component A and the component B in the fine powder have particle sizes of 0.088 mm, and a weight ratio of the component A to the component B is between 1:1 and 6:1.

18. The smelting ladle of claim 13, wherein the SiO.sub.2 fine powder has a content of SiO.sub.2 of 92 wt. % and a particle size of D.sub.505 m; the -Al.sub.2O.sub.3 fine powder has a content of -Al.sub.2O.sub.3 of 99 wt. % and a particle size of D.sub.505 m; the sintered tubular corundum fine powder has a content of Al.sub.2O.sub.3 of 99.5 wt. %, a particle size of D.sub.50=1.7-3.4 m, and a specific area of BET=1.0-4.1 m.sup.2/g; a weight ratio of the SiO.sub.2 fine powder to the active -Al.sub.2O.sub.3 fine powder is between 1:10 and 1:20; and the weight ratio of the SiO.sub.2 fine powder to the sintered tubular corundum fine powder is between 1:10 and 1:20.

19. The smelting ladle of claim 13, wherein: the binder is selected from the group consisting of a calcium aluminate cement, a -Al.sub.2O.sub.3 binder, a silica-alumina gel, and a combination thereof; the calcium aluminate cement comprises 69 wt. % of Al.sub.2O.sub.3 and 30 wt. % of CaO; and the -Al.sub.2O.sub.3 binder comprises 85 wt. % of Al.sub.2O.sub.3.

20. The smelting ladle of claim 13, wherein: the detonation suppressor is a mixture of a tubular organic fiber and a water-soluble organic fiber; the tubular organic fiber has a melting point of 115 C., a length of 4 mm, a diameter of between 60 and 80 m, and a density of 0.56 g/cm.sup.3; the water-soluble organic fiber has a length of 4 mm, a diameter of between 20 and 40 m; and a weight ratio of the tubular organic fiber to the water-soluble organic fiber is between 1.5:1 and 2:1.

21. The smelting ladle of claim 13, wherein the water reducing agent is a polycarboxylate-based water reducing agent.

22. The smelting ladle of claim 13, wherein the foaming agent is selected from the group consisting of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, an aluminum powder, and a mixture thereof; and a particle size of the aluminum powder is between 0.15 and 0.3 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1 is a structure diagram of a first smelting ladle in accordance with one embodiment of the invention;

[0055] FIG. 2 is an enlarged view of Part II of FIG. 1;

[0056] FIG. 3 is a structure diagram of a second smelting ladle in accordance with one embodiment of the invention;

[0057] FIG. 4 is an enlarged view of Part IV of FIG. 3;

[0058] FIG. 5 is a first structure diagram of a third smelting ladle in accordance with one embodiment of the invention;

[0059] FIG. 6 is a cross sectional view taken from line VI-VI of FIG. 5;

[0060] FIG. 7 is an expanded view of an outer permanent layer of FIG. 5;

[0061] FIG. 8 is a second structure diagram of a third smelting ladle in accordance with one embodiment of the invention;

[0062] FIG. 9 is a cross sectional view taken from line IX-IX of FIG. 8; and

[0063] FIG. 10 is an expanded view of an outer permanent layer of FIG. 8.

[0064] In the drawings, the following reference numbers are used: 1. Housing; 2. Permanent layer (21. Inner permanent layer; 22. Outer permanent layer; 22a. First heat insulating block; 22b. Second heat insulating block); 3. Circulating working layer; 4. Consumable working layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0065] For further illustrating the invention, experiments detailing a smelting ladle and a method for improving use efficiency thereof are described hereinbelow combined with the drawings.

EXAMPLE 1

[0066] A first smelting ladle is illustrated in FIGS. 1-2. The smelting ladle comprises a housing 1. A permanent layer 2 is masoned on an inner wall of the housing 1. A circulating working layer 3 is casted on an inner wall of the permanent layer 2, and the consumable working layer 4 is masoned on an inner wall of the circulating working layer 3. Specifically, the permanent layer 2 is masoned by a refractory having a bulk density of 0.50.2 g/cm.sup.3, a compressive strength at a normal temperature of 2.0 megapascal, and a refractory temperature of 1100 C. A thickness of the permanent layer 2 is 65 mm. The circulating working layer 3 is casted by a corundum refractory castable having a bulk density of 2.70.2 g/cm.sup.3 and a refractory temperature of 1600 C. A thickness of the circulating working layer 3 is 100 mm. The consumable working layer 4 is masoned by refractory bricks having a bulk density of 3.00.2 g/cm.sup.3 and a refractory temperature of 1600 C. The thickness of the consumable working layer 4 is 150 mm.

[0067] The construction process of the smelting ladle is as follows: the permanent layer 2 is firstly masoned on the inner wall of the housing 1, and then the circulating working layer 3 is casted on the inner wall of the permanent layer 2. After the moulding, maintenance, and drying processes, the consumable working layer 4 is masoned on the circulating working layer 3.

[0068] In use of the smelting ladle, the consumable working layer 4 directly contacts the molten steel. The consumable working layer 4 is gradually attenuated under the scouring and erosion of the molten steel at the high temperature, and when the consumable working layer 4 is consumed to the thickness of between 0 and 20 mm, a smelting stage of the smelting ladle is completed. Then the smelting ladle is stopped from using and the maintenance thereof is conducted, and a new consumable working layer 4 is masoned again to realize the full utilization of the consumable working layer. During such period, the circulating working layer 3 can be firstly cleaned and repaired when being partially eroded, and the new consumable working layer 4 is then masoned on the outer layer of the circulating working layer 3. The above processes are repeated until the circulating working layer 3 reaches the service life thereof, and the new circulating working layer 3 is re-casted. In this embodiment, the designed service life of the circulating working layer 3 is at least ten smelting stages of the smelting ladle. And in some special circumstance, the circulating working layer 3 can be directly used as the consumable working layer 4 when the consumable working layer 4 is completely consumed.

EXAMPLE 2

[0069] The integral structure of the smelting ladle of Example 2 is the same as that of Example 1 except that the permanent layer 2 is masoned by a refractory having a bulk density of 1.50.2 g/cm.sup.3, a compressive strength at a normal temperature of 8.0 megapascal, and a refractory temperature of 1100 C. A thickness of the permanent layer 2 is 60 mm. The circulating working layer 3 is casted by a corundum refractory castable having a bulk density of 2.90.2 g/cm.sup.3 and a refractory temperature of 1600 C. A thickness of the circulating working layer 3 is 120 mm. The consumable working layer 4 is masoned by refractory bricks having a bulk density of 3.10.2 g/cm.sup.3 and a refractory temperature of 1600 C. The thickness of the consumable working layer 4 is 140 mm.

EXAMPLE 3

[0070] The integral structure of the smelting ladle of Example 3 is the same as that of Example 1 except that the permanent layer 2 is masoned by a refractory having a bulk density of 1.80.2 g/cm.sup.3, a compressive strength at a normal temperature of 10.0 megapascal, and a refractory temperature of 1100 C. A thickness of the permanent layer 2 is 100 mm. The circulating working layer 3 is casted by a corundum refractory castable having a bulk density of 3.10.2 g/cm.sup.3 and a refractory temperature of 1600 C. A thickness of the circulating working layer 3 is 20 mm. The consumable working layer 4 is masoned by refractory bricks having a bulk density of 3.10.2 g/cm.sup.3 and a refractory temperature of 1600 C.; and the thickness of the consumable working layer 4 is 200 mm.

EXAMPLE 4

[0071] A second smelting ladle is illustrated in FIGS. 3-4. The smelting ladle comprises a housing 1. A circulating working layer 3 is casted on an inner wall of the housing 1, and a consumable working layer 4 is masoned on an inner wall of the circulating working layer 3. The smelting ladle of this example is not configured with a permanent layer 2. Specifically, the circulating working layer 3 is moulded by casting a corundum refractory castable having a bulk density of 2.90.2 g/cm.sup.3 and a refractory temperature of 1600 C. A thickness of the circulating working layer 3 is 250 mm. The consumable working layer 4 is masoned by refractory bricks having a bulk density of 3.20.2 g/cm.sup.3 and a refractory temperature of 1600 C. The thickness of the consumable working layer 4 is 80 mm.

[0072] Construction process of the smelting ladle is as follows: the circulating working layer 3 is casted on the inner wall of the housing 1, moulded, maintained, and dried; then the consumable working layer 4 is masoned on the inner wall of the circulating working layer 3.

[0073] The method of using the smelting ladle of Example 4 is substantially the same as those in Examples 1-3, therefore will not be repeated herein.

[0074] The above Examples 1-3 have been tested in the smelting ladle reconstruction on site in a large scale steel plant, and the usages thereof indicate that before the reconstruction of the smelting ladle, an average service life of the permanent layer is approximately 500 heats, an average service life of the working layer is approximately 100 heats, the consumption of the refractory for each ton of the molten steel is approximately 4.5 kilogram, and a total of 13 ton of residual bricks of the working layer are discarded; and after employing the smelting ladle with the long service life and the low material consumption of Examples 1-3, the average service life of the permanent layer 2 exceeds 1000 heats, the average service life of the circulating working layer 3 exceeds 1000 heats, the average service life of the consumable working layer 4 exceeds 135 heats, the consumption of the refractory for each ton of the molten steel is reduced to 2.3 kilogram, and an obsolete quantity of the residual bricks is reduced to 3 tons. Thus, the smelting ladle of the invention is able to greatly reduce the consumption of the refractory for each ton of the molten steel and the obsolete quantity of the consumable working layer on the premise of ensuring the thermal insulation performance of the smelting ladle, therefore effective decrease the operation cost.

EXAMPLE 5

[0075] A third smelting ladle is illustrated in FIGS. 5-7. The smelting ladle comprises a housing 1. A permanent layer 2 is masoned on an inner wall of the housing 1, a circulating working layer 3 is casted on the inner wall of the permanent layer 2, and a consumable working layer 4 is masoned on an inner wall of the circulating working layer 3. The permanent layer 2 is formed by an inner permanent layer 21 contacting with the circulating working layer 3 and an outer permanent layer 22 contacting with the housing 1. The inner permanent layer 21 is masoned by first heat insulating blocks 22a. The outer permanent layer 22 is masoned by alternate arrangement of the first heat insulating blocks 22a and second heat insulating blocks 22b. Specifically, the first heat insulating blocks 22a are alternately disposed in a circumferential direction to form eight circles from top downwards along the inner wall of the housing 1. Four second heat insulating blocks 22b are disposed between adjacent first heat insulating blocks 22a of a same circle. First heat insulating blocks 22a of adjacent two circles are staggered. Similar to a bridge-like structure, the first heat insulating block 22a functions as a bridge pier, and the second heat insulating block 22b functions as a bridge deck.

[0076] In this example, the inner permanent layer 21 has a thickness of between 5 and 50 mm, and the outer permanent layer 22 has a thickness of between 5 and 30 mm. The first heat insulating block 22a employs heat insulating blocks having a compressive strength of between 5 and 20 megapascal, a bulk density of between 0.6 and 1.5 g/cm.sup.3, a thermal conductivity at 800 C. of between 0.20 and 0.50 W/mk. The second heat insulating block 22b employs heat insulating blocks having a compressive strength of between 0.10 and 0.50 megapascal, a bulk density of between 0.2 and 0.5 g/cm.sup.3, and a thermal conductivity at 800 C. of between 0.04 and 0.15 W/mk.

EXAMPLE 6

[0077] Another third smelting ladle is illustrated in FIGS. 8-10. An integral structure of the smelting ladle in this example is basically the same as that of Example 5 except that the first heat insulating blocks 22a are arranged to form a network structure from the top downwards along the inner wall of the housing 1, and four second heat insulating block 22b are filled in rectangular cavities of the network structure. The network structure can also adopt diamond cavities. The first heat insulating blocks and the second heat insulating blocks form structures similar to a Chinese character JIN, the first heat insulating blocks form supporting skeletons, and the multiple second heat insulating blocks form thermal insulation surfaces.

[0078] The smelting ladle of Examples 5-6 utilizes a combined construction of the first heat insulating blocks 22a and the second heat insulating blocks 22b to fully utilize the advantages of both the heat insulating blocks, to ensure the strength and the thermal insulation of the permanent layer, thereby realizing the optimal configuration of the materials. Thus, the smelting ladle possesses not only excellent erosion resistance and high safety performance, but also the excellent thermal insulation performance. The use cycle is further prolonged, the material consumption is reduced, and the service life of the smelting ladle is prolonged.

EXAMPLE 7

[0079] A fourth smelting ladle can also refer to FIG. 1-2. The smelting ladle comprises a housing 1. A permanent layer 2 is masoned on an inner wall of the housing 1, a circulating working layer 3 is casted on the inner wall of the permanent layer 2, and a consumable working layer 4 is masoned on an inner wall of the circulating working layer 3. The castable of the circulating working layer 3 is optimized, and all the raw materials for preparing the castable are purchased from the market, and are specifically as follows:

[0080] The sintered microporous corundum aggregate has a content of Al.sub.2O.sub.3 of 99.5 wt. %, a bulk density of between 3.0 and 3.4 g/cm.sup.3, a closed porosity of 10%, an average pore diameter inside a particle of 1.0 m.

[0081] The magnesia-alumina spinel aggregate comprises between 10 and 40 wt. % of MgO and between 60 and 90 wt. % of Al.sub.2O.sub.3.

[0082] A fused magnesia comprises 97 wt. % of MgO. A sintered magnesia comprises 97 wt. % of MgO.

[0083] The SiO.sub.2 fine powder has a content of SiO.sub.2 of 92 wt. % and a particle size of D.sub.505 m. The -Al.sub.2O.sub.3 fine powder has a content of -Al.sub.2O.sub.3 of 99 wt. % and a particle size of D.sub.505 m.

[0084] The sintered tubular corundum fine powder has a content of Al.sub.2O.sub.3 of 99.5 wt. %, a particle size of D.sub.50=1.7-3.4 m, and a specific area of BET=1.0-4.1 m.sup.2/g. In specific embodiments, three products (product numbers: CL370, CT800, and CTC50) manufactured by Almatis (Qingdao) Co., Ltd., as shown in Table 1:

TABLE-US-00001 TABLE 1 Technical parameters of three materials Product Content of Al.sub.2O.sub.3 Particle size number (wt. %) of D.sub.50 BET CL370 99.5% 2.6 m 3.0 m.sup.2/g CT800 99.5% 3.4 m 1.0 m.sup.2/g CTC50 99.5% 1.7 m 4.1 m.sup.2/g

[0085] The water reducing agent is a polycarboxylate-based water reducing agent, which meets the standard of the Building Industry standard of the People's Republic of China (JG/T223-2007). In specific embodiment, the water reducing agent adopts products (product numbers of ADS1 and ADW1) purchased from the Almatis (Qingdao) Co., Ltd) or products (product numbers of FS60 and FS65) purchased from the BASF company from Germany.

[0086] The calcium aluminate cement has a content of Al.sub.2O.sub.3 of 69 wt. %. The -Al.sub.2O.sub.3 binder has a content of Al.sub.2O.sub.3 of 85 wt. %.

[0087] Both the tubular organic fiber and the water-soluble organic fiber are purchased from Shenyang Sidien Chemical Fiber Co. Ltd. The tubular organic fiber has the melting point of 115 C., a length of 4 mm, a diameter of between 60 and 80 m, and a density of 0.56 g/cm.sup.3. The water-soluble organic fiber has a length of 4 mm and a diameter of between 20 and 40 m.

[0088] Specific formulas of the castable of the circulating working layer 3 are as follows:

Formula for a First Castable

[0089] The castable of the circulating working layer 3 comprises: 55 parts by weight of a sintered microporous corundum aggregate, 10 parts by weight of a magnesia-alumina spinel aggregate, 20 parts by weight of a fine powder, 5 parts by weight of a micropowder, 5 parts by weight of a binder, 0.3 part by weight of a detonation suppressor, 1 part by weight of a water reducing agent, and 0.05 part by weight of a foaming agent.

[0090] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm. Weight percentages thereof are correspondingly as follows: 13 wt. %, 32 wt. %, 18 wt. %, 22 wt. %, and 15 wt. %.

[0091] The fine powder is a mixture of a fused white corundum and a magnesia-alumina spinel, and a weight ratio of the fused white corundum to the magnesia-alumina spinel is 6:1.

[0092] The micropowder is a mixture of a SiO.sub.2 fine powder and an active -Al.sub.2O.sub.3 fine powder, and a weight ratio of the SiO.sub.2 fine powder to the active -Al.sub.2O.sub.3 fine powder is 1:30.

[0093] The binder is the calcium aluminate cement, and a product number of the binder is ADS1/ADW1. The foaming agent is sodium dodecyl sulfate.

[0094] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber. A weight ratio of the tubular organic fiber to the water-soluble organic fiber is 1.5:1.

Formula for a Second Castable

[0095] The castable of the circulating working layer 3 comprises: 60 parts by weight of a sintered microporous corundum aggregate, 5 parts by weight of a magnesia-alumina spinel aggregate, 20 parts by weight of a fine powder, 8 parts by weight of a micropowder, 7 parts by weight of a binder, 0.1 part by weight of a detonation suppressor, 0.1 part by weight of a water reducing agent, and 0.1 part by weight of a foaming agent.

[0096] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm. Weight percentages thereof are correspondingly as follows: 17 wt. %, 28 wt. %, 22 wt. %, 18 wt. %, and 15 wt. %.

[0097] The fine powder is a mixture of a sintered tubular corundum and a fused magnesia, and a weight ratio of the sintered tubular corundum to the fused magnesia is 3:1.

[0098] The micropowder is a SiO.sub.2 micropowder and a sintered tubular corundum fine powder (product number CL370), and a weight ratio of the SiO.sub.2 micropowder to the sintered tubular corundum fine powder is 1:25.

[0099] The binder is a mixture of a -Al.sub.2O.sub.3 binder and an alumina gel, and a weight ratio of the -Al.sub.2O.sub.3 binder to the alumina gel is 3:1.

[0100] A product number of the reducing agent is FS60, and a foaming agent is sodium dodecyl benzene sulfonate (purchased from BASF company from Germany).

[0101] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber. A weight ratio of the tubular organic fiber to the water-soluble organic fiber is 2:1.

Formula for a Third Castable

[0102] The castable of the circulating working layer 3 comprises: 65 parts by weight of a sintered microporous corundum aggregate, 8 parts by weight of a magnesia-alumina spinel aggregate, 25 parts by weight of a fine powder, 6 parts by weight of a micropowder, 4 parts by weight of a binder, 0.2 part by weight of a detonation suppressor, 2 parts by weight of a water reducing agent, and 0.1 part by weight of a foaming agent.

[0103] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm. Weight percentages thereof are correspondingly as follows: 15 wt. %, 30 wt. %, 20 wt. %, 20 wt. %, and 15 wt. %.

[0104] The fine powder is a mixture of a sintered tubular corundum and a sintered magnesia, and a weight ratio of the sintered tubular corundum to the sintered magnesia is 1:1.

[0105] The micropowder is a mixture of a SiO.sub.2 micropowder and a sintered tubular corundum fine powder, and a weight ratio of the SiO.sub.2 micropowder and the sintered tubular corundum fine powder is 1:20. And the sintered tubular corundum fine powder is prepared by mixing a product number of CL370 and a product number of CTC 50 according to a weight ratio of 1:1.

[0106] The binder is an alumina gel; a product number of the reducing agent is FS65; and the forming agent is an aluminum powder.

[0107] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber; and a weight ratio of the tubular organic fiber to the water-soluble organic fiber is 1.8:1.

Formula for a Fourth Castable

[0108] The castable of the circulating working layer 3 comprises: 70 parts by weight of a sintered microporous corundum aggregate, 5 parts by weight of a magnesia-alumina spinel aggregate, 10 parts by weight of a fine powder, 8 parts by weight of a micropowder, 7 parts by weight of a binder, 0.5 part by weight of a detonation suppressor, 0.05 part by weight of a water reducing agent, and 0.1 part by weight of a foaming agent.

[0109] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm; and weight percentages thereof are correspondingly as follows: 16 wt. %, 29 wt. %, 21 wt. %, 21 wt. %, and 13 wt. %.

[0110] The fine powder is a mixture of a sintered tubular corundum and a fused magnesia, and a weight ratio of the sintered tubular corundum to the fused magnesia is 4:1.

[0111] The micropowder is a mixture of a SiO.sub.2 micropowder and an -Al.sub.2O.sub.3 micropowder, and a weight ratio of the SiO.sub.2 micropowder to the -Al.sub.2O.sub.3 micropowder is 1:22.

[0112] The binder is a mixture of a calcium aluminate cement and an alumina gel, and a weight ratio of the calcium aluminate cement to the alumina gel is 2:3. A product number of the reducing agent is ADS1/ADW1. The foaming agent is a mixture of sodium dodecyl benzene sulfonate and an aluminum powder, and a weight ratio of the sodium dodecyl benzene sulfonate to the aluminum powder is 1:1.

[0113] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber; and a weight ratio of the tubular organic fiber to the water-soluble organic fiber is 2:1.

Formula for a Fifth Castable

[0114] The castable of the circulating working layer 3 comprises: 58 parts by weight of a sintered microporous corundum aggregate, 10 parts by weight of a magnesia-alumina spinel aggregate, 20 parts by weight of a fine powder, 6 parts by weight of a micropowder, 6 parts by weight of a binder, 0.5 part by weight of a detonation suppressor, 0.05 part by weight of a water reducing agent, and 0.07 part by weight of a foaming agent.

[0115] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm; and weight percentages thereof are correspondingly as follows: 17 wt. %, 28 wt. %, 18 wt. %, 22 wt. %, and 15 wt. %.

[0116] The fine powder is a mixture of a fused white corundum and a sintered magnesia, and a weight ratio of the fused white corundum to the sintered magnesia is 6:1.

[0117] The micropowder is a mixture of a SiO.sub.2 micropowder and an -Al.sub.2O.sub.3 fine powder, and a weight ratio of the SiO.sub.2 micropowder to the -Al.sub.2O.sub.3 fine powder is 1:30.

[0118] The binder is an alumina gel; a product number of the reducing agent is FS60; and the forming agent is an aluminum powder.

[0119] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber; and a weight ratio of the tubular organic fiber and the water-soluble organic fiber is 1.7:1.

Formula for a Sixth Castable

[0120] The castable of the circulating working layer 3 comprises: 66 parts by weight of a sintered microporous corundum aggregate, 5 parts by weight of a magnesia-alumina spinel aggregate, 15 parts by weight of a fine powder, 8 parts by weight of a micropowder, 6 parts by weight of a binder, 0.1 part by weight of a detonation suppressor, 0.1 part by weight of a water reducing agent, and 0.1 part by weight of a foaming agent.

[0121] The sintered microporous corundum aggregate is divided into particles of five levels according to particle sizes thereof: 12 mm<a particle size of a first level25 mm, 7 mm<the particle size of a second level12 mm, 3 mm<the particle size of a third level7 mm, 1 mm<the particle size of a fourth level3 mm, and 0 mm<the particle size of a fifth level1 mm; and weight percentages thereof are correspondingly as follows: 13 wt. %, 32 wt. %, 22 wt. %, 18 wt. %, and 15 wt. %.

[0122] The fine powder is a mixture of a fused white corundum and a sintered tubular corundum (product number of CTC50 or CT800), and a weight ratio of the fused white corundum to the sintered tubular corundum is 1:1.

[0123] The micropowder is a mixture of a SiO.sub.2 micropowder and an -Al.sub.2O.sub.3 fine powder, and a weight ratio of the SiO.sub.2 micropowder to the -Al.sub.2O.sub.3 fine powder is 1:20.

[0124] The binder is a -Al.sub.2O.sub.3 binder. A product number of the reducing agent is ADS1/ADW1. The forming agent is sodium dodecyl sulfate.

[0125] The detonation suppressor is a mixture of the tubular organic fiber and the water-soluble organic fiber; and a weight ratio of the tubular organic fiber to the water-soluble organic fiber is 2:1.

[0126] A method for preparing the above six castables comprises:

[0127] 1) weighing the sintered microporous corundum aggregate, the magnesia-alumina spinel aggregate, the fine powder, the micro powder, the binder, the detonation suppressor, the water reducing agent, and the foaming agent;

[0128] 2) uniformly premixing the fine powder, the micropowder, the binder, the detonation suppressor, the water reducing agent, and the forming agent in a premixer to obtain a premix;

[0129] 3) adding the premix, the sintered microporous corundum aggregate, and magnesia-alumina spinel aggregate to a forced mixer for stirring until materials are uniformly stirred, and discharging and packing a resulting mixture to yield the castable.

[0130] When casting the circulating working layer, an required amount of the castable is collected and added with water having a weight accounting for between 4.5 and 6.0 wt. % of the castable for mixing for between 3 and 5 min, and a resulting mixture is then moulded by casting.

[0131] Performances of the circulating working layers manufactured by the above six castables are listed in Table 2.

TABLE-US-00002 TABLE 2 Performances of the circulating working layers manufactured by six castables Circulating working layer Circulating working layers manufactured by six castable Parameters 1 2 3 4 5 6 Sintered Flexural strength 15 15 15 15 15 15 under (megapascal) 110 C. Compressive strength 110 110 110 110 110 110 24 hr (megapascal) Bulk density (g/cm.sup.3) 2.92 2.90 2.91 2.90 2.92 2.93 Sintered Flexural strength 40 40 40 40 40 40 under (megapascal) 1600 C. Compressive strength 180 180 180 180 180 180 3 hr (megapascal) Linear change rate (%) +0.52 +0.58 +0.58 +0.53 +0.50 +0.59 Flexural strength (megapascal) 3.53 3.81 3.66 3.72 3.65 3.76 (sintered under 1400 C. 0.5 hr) Thermal shock resistance (times) 18 20 18 19 20 20

[0132] Unless otherwise indicated, the numerical ranges involved in the invention include the end values. While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.