Zircon-based sintered concrete

1. A sintered concrete having the following chemical composition, as mass percentages on the basis of the oxides and for a total of 100%:

ZrO 2 : 55 to 70%,

SiO 2 : 25 to 40%,

P 2 O 5 : 0.2 to 9.0%,

Al 2 O 3 : 0.5 to 7.0%,

CaO: >0.2%,

CaO+MgO+B 2 O 3 +Fe 2 O 3 : 0.2 to 10.0%,

MgO+B 2 O 3 +Fe 2 O 3 : ≤7.5%,

B 2 O 3 +MgO: ≤4.5%,

ZrO 2 +SiO 2 +P 2 O 5 +Al 2 O 3 +CaO+MgO+B 2 O 3 +Fe 2 O 3 : ≥95.0%, said sintered concrete having crystalline phases and containing more than 70% of zircon, as a mass percentage on the basis of the mass of the crystalline phases, the oxides representing more than 98.5% of the mass of the sintered concrete.

2. The sintered concrete as claimed in claim 1 , said composition being such that:

the content of ZrO 2 is greater than 57% and less than 67%; and/or

the content of SiO 2 is greater than 26% and less than 37%; and/or

the content of P 2 O 5 is greater than 0.3% and less than 8.5%; and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.3% and less than 9.5%; and/or

the content of CaO is greater than 0.3% and less than 7.9%; and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 7.0%; and/or

the sum of the contents of MgO and B 2 O 3 is less than 4%; and/or

the sum of the contents of oxides other than ZrO 2 , SiO 2 , P 2 O 5 , Al 2 O 3 , CaO, MgO, B 2 O 3 and Fe 2 O 3 is less than 4.5%.

3. The sintered concrete as claimed in claim 1 , said composition being such that:

the content of ZrO 2 is greater than 58% and less than 65%; and/or

the content of SiO 2 is greater than 27% and less than 35%; and/or

the content of P 2 O 5 is greater than 0.7% and less than 5.0%; and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.5% and less than 5.9%; and/or

the content of CaO is greater than 0.4% and less than 5.0%; and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 3.5%; and/or

the sum of the contents of MgO and B 2 O 3 is less than 2.4%; and/or

the sum of the contents of oxides other than ZrO 2 , SiO 2 , P 2 O 5 , Al 2 O 3 , CaO, MgO, B 2 O 3 and Fe 2 O 3 is less than 3.0%.

4. The sintered concrete as claimed in claim 1 , in which the content of zircon, as a mass percentage on the basis of the crystalline phases, is greater than 80%.

5. The sintered concrete as claimed in claim 1 , which is in the form of a block, all the dimensions of which are greater than 1 mm.

6. The sintered concrete as claimed in claim 1 , having the following chemical composition, as mass percentages on the basis of the oxides and for a total of 100%:

ZrO 2 : 55 to 70%,

SiO 2 : 25 to 40%,

CaO: 0.2 to 3.0%,

Al 2 O 3 : 0.5 to 7.0%,

MgO: 0.1 to 3.0%,

P 2 O 5 : 0.3 to 9.0%,

other oxides: <5.0%.

7. The sintered concrete as claimed in claim 6 , said composition being such that:

ZrO 2 >59%, and/or

SiO 2 >27%, and/or

CaO>0.4%, and/or

Al 2 O 3 >1.0%, and/or

MgO>0.3%, and/or

P 2 O 5 >0.7%.

8. The sintered concrete as claimed in claim 7 , said composition being such that:

ZrO 2 >61%, and/or

SiO 2 >29%, and/or

CaO>0.5%, and/or

Al 2 O 3 >1.5%, and/or

MgO>0.4%, and/or

P 2 O 5 >1.2%.

9. The sintered concrete as claimed in claim 1 , said composition being such that:

ZrO 2 <67%, and/or

SiO 2 <35%, and/or

CaO<2.0%, and/or

Al 2 O 3 <6.0%, and/or

MgO<2.1%, and/or

P 2 O 5 <5.0%, and/or

other oxides <3.5%.

10. The sintered concrete as claimed in claim 9 , said composition being such that:

ZrO 2 <65%, and/or

SiO 2 <31%, and/or

CaO<1.2%, and/or

Al 2 O 3 <4.0%, and/or

MgO<0.9%, and/or

P 2 O 5 <3.0%, and/or

other oxides <2%.

11. The sintered concrete as claimed in claim 1 , in which:

the content of P 2 O 5 is greater than 0.3% and less than 5.8%, and

the content of Fe 2 O 3 is greater than 0.1% and less than 6.5%, and

the content of MgO is less than 0.5%, and

the content of B 2 O 3 is less than 0.5%, and

the content of CaO is greater than 0.3% and less than 3%, and

the sum of the contents of MgO and B 2 O 3 is less than 1%, and

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.3% and less than 10%, and

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.1% and less than 7.0%.

12. The sintered concrete as claimed in claim 11 , in which:

the content of P 2 O 5 is greater than 0.5% and less than 3.0%, and/or

the content of Fe 2 O 3 is greater than 0.5% and less than 3.5%, and/or

the content of MgO is less than 0.3%, and/or

the content of B 2 O 3 is less than 0.3%, and/or

the content of CaO is greater than 0.4% and less than 2.0%, and/or

the sum of the contents of MgO and B 2 O 3 is less than 0.6%, and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.7% and less than 5.1%, and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.5% and less than 4.4%.

13. The sintered concrete as claimed in claim 1 , in which:

the content of P 2 O 5 is greater than 0.25% and less than 8.3%, and

the content of B 2 O 3 is greater than 0.05% and less than 4.0%, and

the content of MgO is less than 0.5%, and

the content of Fe 2 O 3 is less than 0.5%, and

the content of CaO is greater than 0.3% and less than 3%, and

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.3% and less than 8.0%, and

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.05% and less than 5.0%, and

the sum of the contents of MgO and B 2 O 3 is greater than 0.05% and less than 4.5%.

14. The sintered concrete as claimed in claim 13 , in which:

the content of P 2 O 5 is greater than 0.7% and less than 4.5%, and/or

the content of B 2 O 3 is greater than 0.2% and less than 2.0%, and/or

the content of MgO is less than 0.3%, and/or

the content of Fe 2 O 3 is less than 0.3%, and/or

the content of CaO is greater than 0.4% and less than 1.5%, and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.5% and less than 4.2%, and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.2% and less than 3.0%, and/or

the sum of the contents of MgO and B 2 O 3 is greater than 0.2% and less than 3.0%.

15. The sintered concrete as claimed in claim 1 , in which:

the content of P 2 O 5 is greater than 0.25% and less than 7.0%, and

the content of CaO is greater than 0.3% and less than 8.4%, and

the content of B 2 O 3 is less than 0.5%, and

the content of MgO is less than 0.5%, and

the content of Fe 2 O 3 is less than 0.5%, and

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.3% and less than 9.5%, and

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 1.5%, and

the sum of the contents of MgO and B 2 O 3 is less than 1.0%.

16. The sintered concrete as claimed in claim 15 , in which:

the content of P 2 O 5 is greater than 0.4% and less than 3.5%, and/or

the content of CaO is greater than 0.8% and less than 5.0%, and/or

the content of B 2 O 3 is less than 0.3%, and/or

the content of MgO is less than 0.3%, and/or

the content of Fe 2 O 3 is less than 0.3%, and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.7% and less than 4.5%, and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 0.5%, and/or

the sum of the contents of MgO and B 2 O 3 is less than 0.5%.

17. The sintered concrete as claimed in claim 1 , in which:

the content of P 2 O 5 is greater than 0.25% and less than 6.5%, and

the content of Al 2 O 3 is greater than 0.8% and less than 6.5%, and

the content of B 2 O 3 is less than 0.5%, and

the content of MgO is less than 0.5%, and

the content of Fe 2 O 3 is less than 0.5%, and

the content of CaO is greater than 0.3% and less than 3%, and

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.2% and less than 4.5%, and

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 1.5%, and

the sum of the contents of MgO and B 2 O 3 is less than 1.0%.

18. The sintered concrete as claimed in claim 17 , in which:

the content of P 2 O 5 is greater than 0.6, and/or

the content of Al 2 O 3 is greater than 1.5% and less than 6.0%, and/or

the content of B 2 O 3 is less than 0.3%, and/or

the content of MgO is less than 0.3%, and/or

the content of Fe 2 O 3 is less than 0.3%, and/or

the content of CaO is greater than 0.4% and less than 2.0%, and/or

the sum of the contents of CaO, MgO, B 2 O 3 and Fe 2 O 3 is greater than 0.3% and less than 3.0%, and/or

the sum of the contents of MgO, B 2 O 3 and Fe 2 O 3 is less than 1.0%, and/or

the sum of the contents of MgO and B 2 O 3 is less than 0.5%.

19. A process for manufacturing a sintered concrete, said process comprising the following successive steps:

a) mixing particulate starting materials to form a feedstock,

b) activating said feedstock so as to obtain a fresh concrete,

c) forming said fresh concrete,

d) hardening said fresh concrete so as to obtain a hardened concrete,

e) sintering said hardened concrete so as to obtain said sintered concrete, the feedstock being adapted so that said sintered concrete is in accordance with claim 1 .

20. The process as claimed in claim 19 , in which the feedstock includes

between 1.0% and 6.0% by weight of a hydraulic binder, and

more than 0.25% of a phosphate chosen from magnesium phosphates, iron phosphates, boron phosphates, calcium phosphates, aluminum phosphates and mixtures thereof, said phosphate providing more than 50% of the phosphorus of the feedstock.

21. The process as claimed in claim 19 , in which the feedstock is such that, as mass percentages on the basis of the feedstock,

the mass amount of zircon particles is greater than 75% and less than 95%, and/or

the mass amount of free zirconia particles is greater than 1.0% and less than 20.0%, and/or

the mass amount of hydraulic binder in the feedstock is greater than 1.5% and less than 5.0%, and/or

the mass amount of said phosphate is greater than 0.3% and less than 14.0%.

22. The process as claimed in claim 21 , in which the feedstock is such that, as mass percentages on the basis of the feedstock,

the mass amount of zircon particles is less than 90%, and/or

the mass amount of free zirconia particles is greater than 5.0% and less than 15.0%, and/or

the mass amount of hydraulic binder in the feedstock is greater than 2.0% and less than 4.0%, and/or

the mass amount of said phosphate is greater than 1.0% and less than 5.0%.

23. The process as claimed in claim 20 , in which the hydraulic binder is a cement.

24. The process as claimed in claim 23 , in which the cement is an aluminous cement.

25. The process as claimed in claim 20 , in which the alumina content of the hydraulic binder is between 50% and 85%.

26. The process as claimed in claim 20 , in which the only phosphate present in the feedstock is Mg(PO 3 ) 2 .nH 2 O or FePO 4 .nH 2 O or BPO 4 .nH 2 O or Ca 2 P 2 O 7 .nH 2 O or AlPO 4 .nH 2 O, with n≥0.

27. A glass production unit, including a component made of a sintered concrete as claimed in any one of claims 1 to 18 .

28. A glass production unit including a component made of a sintered concrete as claimed in claim 1 , said component being selected from the group consisting of:

a plate block,

a floor slab,

a superstructure component,

a channel block of a feed channel,

a burner unit,

an expandable,

a mandrel used in the manufacture of glass tubes according to the Danner process, and

an electrode holder block.

29. The glass production unit as claimed in claim 28 , in which the expendable is a tube, a plunger, a stirrer, a rotor, an orifice ring, a spout.

30. The process as claimed in claim 21 , in which said phosphate is Mg(PO 3 ) 2 .

31. The process as claimed in claim 22 , in which said phosphate is Mg(PO 3 ) 2 .