METHOD FOR SIMULTANEOUS EXHAUST GAS CLEANING AND MANUFACTURING OF SUPPLEMENTARY CEMENTITOUS MATERIAL

Abstract

A method for manufacturing a binder of a hydratable material includes providing a starting material from one or more raw materials convertible by tempering at 600 to 1200 C. into the hydratable material and tempering the starting material to provide the hydratable material containing not more than 10% by weight monocalcium silicate and at least 15% by weight hydratable phases in the form of lime and dicalcium silicate. The residence time and the tempering temperature are adapted to obtain the hydratable material by converting not more than 80% by weight of the starting material, and the hydratable material is then cooled to provide the binder comprising the hydratable material. The binder can be mixed with water and optionally one or more of aggregate, additives, admixtures to obtain a binder paste that is placed, hydrated and carbonated to produce a building product.

Claims

1. A method for simultaneous cleaning of exhaust gas from CO.sub.2 and manufacturing a supplementary cementitious material from recycled concrete fines, comprising the steps: providing recycled concrete fines with d.sub.901000 m in a stockpile or silo as starting material flushing the starting material with the exhaust gas providing a carbonated material, withdrawing the carbonated material and cleaned exhaust gas, and de-agglomerating the carbonated material to form the supplementary cementitious material.

2. The method according to claim 1, wherein the recycled concrete fines are mixed with additional material to form the starting material.

3. The method according to claim 1, wherein the supplementary cementitious material has or is ground to a particle size distribution of D.sub.90 below 90 m (determined by laser granulometry) and a Rosin-Rammler slope n from 0.6 to 1.4.

4. The method according to claim 1, wherein carbonation is carried out until the supplementary cementitious material contains 1.25 times more CO.sub.2 than the starting material.

5. The method according to claim 1, additionally comprising grinding of the starting material.

6. The method d according to claim 1, wherein the exhaust gas is additionally cleaned of SO.sub.x with x from 0 to 3.

7. The method according to claim 1, wherein the exhaust gas is at a temperature from 10 to 150 C. and at ambient pressure or at 0.01 to 4 bar overpressure.

8. The method according to claim 1, wherein exhaust gas from a cement plant, a coal fired power plant or from waste incineration is cleaned.

9. The method according to claim 1, wherein the exhaust gas is treated to increase the concentration of contained CO.sub.2 and/or SO.sub.x.

10. The method according to claim 1, wherein sulphur is removed from or diminished in the exhaust gas prior to flushing the starting material with the exhaust gas.

11. The method according to claim 1, wherein the exhaust gas is introduced at a bottom of the stockpile or silo and flows through the starting material in vertical direction.

12. The method according to claim 1, wherein the cleaned exhaust gas is further subjected to one or more of: dust removal, gas cooling, gas conditioning, heat recovery, and/or used for drying of wet materials.

13. (canceled)

14. The method according to claim 3, wherein carbonation is carried out until the supplementary cementitious material contains 1.75 times more CO.sub.2 than the starting material.

15. The method according to claim 2, additionally comprising grinding of the starting material.

16. The method according to claim 7, wherein exhaust gas from a cement plant, a coal fired power plant or from waste incineration is cleaned.

17. The method according to claim 3, wherein the cleaned exhaust gas is further subjected to one or more of: dust removal, gas cooling, gas conditioning, heat recovery, and/or used for drying of wet materials.

18. The method according to claim 4, wherein the exhaust gas is at a temperature from 20 to 100 C. and at ambient pressure or at 0.1 to 2 bar overpressure.

19. The method according to claim 4, wherein exhaust gas from a cement plant, a coal fired power plant or from waste incineration is cleaned and the exhaust gas is at a temperature from 10 to 150 C. and at ambient pressure or at 0.01 to 4 bar overpressure.

20. The method according to claim 19, wherein the cleaned exhaust gas is further subjected to one or more of: dust removal, gas cooling, gas conditioning, heat recovery, and/or used for drying of wet materials.

21. The method according to claim 8, wherein the exhaust gas is treated to increase the concentration of contained CO.sub.2 and/or SO.sub.x.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0064] FIG. 4 schematically shows an embodiment of the method according to the invention using a stockpile,

[0065] FIG. 5 schematically shows an embodiment of the method according to the invention using a silo.

[0066] In FIG. 4 the recycled concrete fines are stockpiled, optionally after a mechanical pretreatment. The stockpile 1 comprises a gas introduction system 2 comprising conduits 3 and gas distributors 4. Exhaust gas 5 is passed into the conduits 3 and discharged into the stockpile 1 by the distributors 4. The conduits 3 are arranged at the bottom of the stockpile 1. Exhaust gas 5 is introduced into the RCF by the distributors 4, which can be nozzles for example. The exhaust gas 5 flows in vertical direction with respect to the stockpile 1 thereby contacting contained CO.sub.2 and/or SO.sub.x with the waste material. The RCF is carbonated and/or sulphurized by flushing the stockpile bed with the exhaust gases containing CO.sub.2 and/or SO.sub.x.

[0067] FIG. 5 schematically shows an embodiment of the method according to the invention, wherein the recycled concrete fines are placed into a silo 10, optionally after the pretreatment. Carbonation and/or sulphurization of the RCF is performed in the silo 10 by exhaust gas 50. This is provided by gas distribution system 20 through conduits 30 arranged at the bottom of the silo 10 and introduced through distributors 40. The exhaust gas 50 flows in vertical direction with respect to the silo 10. The starting material is carbonated and/or sulphurized by flushing the exhaust gas 50 through the starting material. The silo 10 can contain a bottom discharge outlet 60 for withdrawing the obtained carbonated/sulphurized RCF.

LIST OF REFERENCE NUMBERS

[0068] 1 stockpile [0069] 2 gas introduction system [0070] 3 conduit [0071] 4 gas distributor [0072] 5 exhaust gas [0073] RCF waste material [0074] 10 silo [0075] 20 gas introduction system [0076] 30 conduit [0077] 40 gas distributor [0078] 50 exhaust gas [0079] 60 carbonated RCF discharge [0080] RCF waste material