Manufacturing a binder with high β belite content
The present invention relates to a method for manufacturing a binder with high β belite content comprising the steps: a) providing a starting material by selecting one raw material having a Ca/Si molar ratio of 1.5 to 2.5 or by mixing two or more raw materials to obtain a starting material with the Ca/Si molar ratio of 1.5 to 2.5; b) hydrothermal treatment of the starting material produced in step a) in an autoclave at a temperature of 100 to 300° C. and a retention time of 0.1 to 24 h, wherein the water/solids ratio is from 0.1 to 100 to provide an intermediate product; c) annealing the intermediate product obtained in step b) in a flash calciner at 620 to 630° C., wherein the retention time is 1-30 seconds.
1. A method for manufacturing a binder with β belite content of at least 20% by weight comprising the steps:
a) providing a starting material by selecting one raw material having a Ca/Si molar ratio of 1.5 to 2.5 or by mixing two or more raw materials to obtain a starting material with the Ca/Si molar ratio of 1.5 to 2.5;
b) hydrothermal treatment of the starting material produced in step a) in an autoclave at a temperature of 100 to 300° C. and a retention time of 0.1 to 24 h, wherein the water/solid ratio is from 0.1 to 100 to provide an intermediate product;
c) annealing the intermediate product obtained in step b) in a flash calciner at 620 to 630° C., wherein the retention time is 1-30 seconds.
2. The method according to claim 1 , wherein the molar ratio of calcium to silicon in the starting material is 2±10%.
3. The method according to claim 1 , wherein primary and/or secondary raw materials are used to provide the starting material, the primary and/or secondary raw materials being selected from the group consisting of quartz, sand, gravel, limestone, portlandite (Ca(OH) 2 ), burnt lime, unburnt lime, silicious fly ash, calcareous fly ash, and grain fractions from the reprocessing of cement-containing binders in building materials, and mixtures thereof.
4. The method according to claim 1 , wherein the raw material(s) is(are) are optimised with respect to particle size and particle size distribution by mechanical or thermal treatment.
5. The method according to claim 1 , wherein additional elements, also in the form of compounds, are added in an amount from 0.1 to 30% by weight to the raw material or during the mixing of the raw materials, for hydrothermal treatment or for annealing.
6. The method according to claim 1 , wherein the starting material is seeded with 0.01-30% by weight of seed nuclei containing at least one calcium silicate hydrate.
7. The method according to claim 1 , wherein one or more of the raw materials or the starting material is burnt at temperatures of 400 to 1400° C.
8. The method according to claim 1 , wherein hydrothermal treatment occurs at a temperature of 150° C. to 250° C., with a water/solids ratio of 2 to 20, and retention times of 1 to 16 hours.
9. The method according to claim 1 , wherein the intermediate product is annealed at a temperature of 625° C.±2° C. with a retention time of 1 to 3 seconds.
10. The method according to claim 2 , wherein primary and/or secondary raw materials are used to provide the starting material, the primary and/or secondary raw materials being selected from the group consisting of quartz, sand, gravel, limestone, portlandite (Ca(OH) 2 ), burnt lime, unburnt lime, silicious fly ash, calcareous fly ash, grain fractions from the reprocessing of cement-containing binders in building materials, and mixtures thereof.
11. The method according to claim 2 , wherein the raw material(s) is(are) optimised with respect to particle size and particle size distribution by mechanical or thermal treatment.
12. The method according to claim 10 , wherein the raw material(s) is(are) optimised with respect to particle size and particle size distribution by mechanical or thermal treatment.
13. The method according to claim 5 , wherein the additional elements are selected from the group consisting of sodium, potassium, boron, sulphur, phosphorous and combinations thereof.
14. The method according to claim 6 , wherein the calcium silicate hydrate is one or more of α-C 2 SH, afwillite, calcio-chondrodite.
15. The method according to claim 7 , wherein the starting material is burnt at temperatures of 750 to 1100° C.
16. The method according to claim 4 , wherein additional elements, also in the form of compounds, are added in an amount from 0.1 to 30% by weight to the raw material or during the mixing of the raw materials, for hydrothermal treatment or for annealing.
17. The method according to claim 4 , wherein hydrothermal treatment occurs at a temperature of 150° C. to 250° C., with a water/solids ratio of 2 to 20, and retention times of 1 to 16 hours.
18. The method according to claim 17 , wherein the intermediate product is annealed at a temperature of 625° C.±2° C. with a retention time of 1 to 3 seconds.
19. The method according to claim 3 , wherein additional elements, also in the form of compounds, are added in an amount from 0.1 to 30% by weight to the raw material or during the mixing of the raw materials, for hydrothermal treatment or for annealing.
20. The method according to claim 3 , wherein the intermediate product is annealed at a temperature of 625° C.±2° C. with a retention time of 1 to 3 seconds.