Composite refractory for an inner lining of a blast furnace

1. A refractory, comprising:

a protective layer and a conductive layer together forming a layered composite refractory and configured with an interlayer bonding strength between the individual said layers of more than 6 MPa;

wherein said layered composite refractory does not contain a glue and/or a mechanical fastening element; and

wherein a flexural strength of at least one of said layers or a flexural strength of all of said layers is greater than the interlayer bonding strength.

2. The refractory according to claim 1 , wherein said interlayer bonding strength between the individual said layers is at least 7 MPa or greater.

3. The refractory according to claim 1 , consisting of said protective layer and said conductive layer.

4. The refractory according to claim 1 , consisting of said protective layer, said conductive layer, and one or more intermediate layers arranged between said protective layer and said conductive layer.

5. The refractory according to claim 1 , formed in a body of an at least substantially cuboidal configuration, and wherein said layers are bonded together along base surfaces or lateral surfaces thereof.

6. The refractory according to claim 3 , formed in a body with an at least substantially cuboidal configuration with said protective layer and said conductive layer bonded together along base surfaces thereof, and wherein a thickness of said protective layer is 10 to 25% or 30 to 45% of a total thickness of the refractory.

7. The refractory according to claim 3 , formed in a body with an at least substantially cuboidal configuration, with said protective layer and said conductive layer bonded together along lateral surfaces thereof, and wherein a thickness of said protective layer is 10 to 25% of a total thickness of the refractory or 30 to 45% of the total thickness of the refractory.

8. The refractory according to claim 4 , formed in a body of an at least substantially cuboidal configuration, with said protective layer, said conductive layer and said one or more intermediate layers bonded together along base surfaces thereof, and wherein a thickness of said protective layer is 10 to 40%, a total thickness of all intermediate layers is 5 to 25%, and a thickness of said conductive layer is 45 to 85% of a total thickness of the refractory.

9. The refractory according to claim 4 , formed in a body of an at least substantially cuboidal configuration, with said protective layer, said conductive layer, and said one or more intermediate layers bonded together along lateral surfaces thereof, and wherein a thickness of said protective layer is 10 to 40%, a total thickness of all intermediate layers is 5 to 25%, and a thickness of said conductive layer is 45 to 85% of a total thickness of the refractory.

10. The refractory according to claim 1 , wherein said conductive layer has a given thermal conductivity at 1500° C., and the thermal conductivity of said conductive layer is at least 25% or more greater than a thermal conductivity of said protective layer.

11. The refractory according to claim 1 , wherein a difference between a thermal expansion coefficient of said conductive layer and a thermal expansion coefficient of said protective layer at a temperature between 23° C. and 1500° C. is at most 0.6 μm/(Km).

12. The refractory according to claim 1 , having the characteristics of a refractory obtained by a process comprising the following steps:

a) providing a mixture for the protective layer, a mixture for the conductive layer, and optionally a mixture for one or more intermediate layers;

b) forming a layered green block from the mixtures provided in step a); and

c) baking the green block of step b).

13. The refractory according to claim 12 , wherein the forming step b) comprises a step selected from the group consisting of vibro-molding, block-pressing, uniaxial-pressing, and isostatic-pressing.

14. The refractory according to claim 12 , wherein the mixture for the protective layer provided in step a) contains at least 20% by weight of a carbonaceous material and at least 3% by weight of silicon based on the dry aggregate of the mixture and a binder.

15. The refractory according to claim 14 , wherein the carbonaceous material is calcined anthracite.

16. The refractory according to claim 14 , wherein the mixture for the protective layer provided in step a) further contains an oxidic ceramic.

17. The refractory according to claim 16 , wherein the oxidic ceramic is selected from the group consisting of aluminum oxide, titanium dioxide, aluminum silicate and mixtures of two or more of the aforementioned compounds.

18. The refractory according to claim 14 , wherein the mixture for the protective layer provided in step a) further contains a non-oxidic ceramic.

19. The refractory according to claim 18 , wherein the non-oxidic ceramic is selected from the group consisting of metal carbonitrides, metal carbides, metal borides, metal nitrides and mixtures of two or more of the aforementioned compounds.

20. The refractory according to claim 14 , wherein the mixture for the protective layer provided in step a) further contains graphite.

21. The refractory according to claim 14 , wherein the mixture for the protective layer provided in step a) contains

a dry mixture of:

10 to 95% by weight of calcined anthracite optionally in admixture with another carbonaceous material,

3 to 20% by weight of silicon,

2 to 30% by weight of an oxidic ceramic selected from the group consisting of aluminum oxide, titanium dioxide, aluminum silicate and mixtures of two or more of the aforementioned compounds,

0 to 20% by weight of a non-oxidic ceramic and

0 to 30% by weight of synthetic or natural graphite or a mixture of both and

at least one binder.

22. The refractory according to claim 15 , wherein the mixture for the conductive layer provided in step a) contains at least 20% by weight of synthetic graphite or natural graphite or a mixture thereof based on the dry aggregate of the mixture and a binder.

23. The refractory according to claim 22 , wherein the mixture for the conductive layer further contains at least 10% by weight of a further carbonaceous material.

24. The refractory according to claim 22 , wherein the mixture for the conductive layer further contains an oxidic ceramic.

25. The refractory according to claim 24 , wherein the oxidic ceramic is selected from the group consisting of aluminum oxide, titanium dioxide, aluminum silicate and mixtures of two or more of the aforementioned compounds.

26. The refractory according to claim 22 , wherein the mixture for the conductive layer provided in step a) further contains silicon.

27. The refractory according to claim 22 , wherein the mixture for the conductive layer provided in step a) contains

a dry mixture of:

20 to 80% by weight of synthetic or natural graphite or a mixture of both,

20 to 80% by weight of calcined anthracite optionally in admixture with another carbonaceous material,

0 to 20% by weight of silicon and

0 to 20% by weight of an oxidic ceramic selected from the group consisting of aluminum oxide, titanium dioxide, aluminum silicate and mixtures of two or more of the aforementioned compounds

and

at least one binder.

28. The refractory according to claim 12 , wherein in step c) the green block is baked at a temperature between 1100 and 1400° C.

29. The refractory according to claim 28 , wherein the block is impregnated after the baking according to step c) with an impregnation agent, and wherein the impregnated green block is rebaked at a temperature between 900 and 1300° C.

30. A blast furnace, comprising an inner lining formed with at least one refractory according to claim 1 .

31. An inner lining of a blast furnace, comprising a plurality of refractories according to claim 1 disposed to form the inner lining of the blast furnace.

32. A refractory, comprising:

a protective layer and a conductive layer together forming a layered composite refractory and configured with an interlayer bonding strength between the individual said layers of more than 6 MPa;

wherein a flexural strength of at least one of said layers or a flexural strength of all of said layers is greater than the interlayer bonding strength;

the refractory having the characteristics of a refractory obtained by a process comprising the following steps:

a) providing a mixture for the protective layer, a mixture for the conductive layer, and optionally a mixture for one or more intermediate layers;

b) forming a layered green block from the mixtures provided in step a); and

c) baking the green block of step b); and

wherein the mixture for the protective layer provided in step a) contains at least 20% by weight of a carbonaceous material, at least 3% by weight of silicon based on the dry aggregate of the mixture, a binder, and an oxidic and a ceramic.

33. A refractory, comprising:

a protective layer and a conductive layer together forming a layered composite refractory and configured with an interlayer bonding strength between the individual said layers of more than 6 MPa;

wherein a flexural strength of at least one of said layers or a flexural strength of all of said layers is greater than the interlayer bonding strength;

the refractory having the characteristics of a refractory obtained by a process comprising the following steps:

a) providing a mixture for the protective layer, a mixture for the conductive layer, and optionally a mixture for one or more intermediate layers;

b) forming a layered green block from the mixtures provided in step a); and

c) baking the green block of step b);

the mixture for the protective layer provided in step a) containing a dry mixture of:

10 to 95% by weight of calcined anthracite optionally in admixture with another carbonaceous material,

3 to 20% by weight of silicon,

2 to 30% by weight of an oxidic ceramic selected from the group consisting of aluminum oxide, titanium dioxide, aluminum silicate and mixtures of two or more of the aforementioned compounds;

an optional amount of 0 to 20% by weight of a non-oxidic ceramic; and

an optional amount of 0 to 30% by weight of synthetic or natural graphite or a mixture of both;

and a binder.

34. The refractory according to claim 1 , wherein each of said protective layer and said conductive layer is based on a carbonaceous material.