Process and device for carbonating concrete waste and/or sequestering CO
A method for manufacturing supplementary cementitious material and sequestering CO 2 by carbonating concrete fines has the following steps: grinding the concrete fines obtained from crushed concrete demolition waste in a mill at a temperature from 1 to 10° C. above the water dew point in a carbonating atmosphere provided by a gas containing from 10 to 99 Vol.-% CO 2 , circulating the ground and partially carbonated concrete fines in a fluidized bed reactor in contact with the carbonating atmosphere, and withdrawing decarbonated gas and carbonated concrete fines.
1. A method for manufacturing supplementary cementitious material and sequestering CO 2 by carbonating concrete fines comprising the steps:
grinding the concrete fines obtained from crushed concrete demolition waste in a mill at a temperature from 1 to 10° C. above the water dew point in a carbonating atmosphere provided by a gas containing from 10 to 99 Vol.-% CO 2 ,
circulating the ground and partially carbonated concrete fines in a fluidized bed reactor in contact with the carbonating atmosphere, and
withdrawing decarbonated gas and carbonated concrete fines with recirculation of some of the gas and concrete fines to the reactor and/or mill, wherein at least 80 wt.-% of the concrete fines are carbonated.
2. The method according to claim 1 , wherein the concrete fines are adjusted to a particle size distribution determined via sieving or laser granulometry with a d 90 ≤2 mm.
3. The method according to claim 1 , wherein the temperature is adjusted to a range from 2 to 7° C. above the water dew point.
4. The method according to claim 1 , wherein the carbonating atmosphere contains from 10 to 30 Vol.-% CO 2 or from 50 to 90 Vol.-% CO 2 .
5. The method according to claim 1 , wherein the carbonating atmosphere is an exhaust gas from a coal fired power plant, a cement plant or a cement plant operating in an oxyfuel mode, or a gas concentrated in CO 2 .
6. The method according to claim 1 , wherein the ground and partially carbonated concrete fines are recirculated on average 10 to 100 times to the reactor and/or the mill.
7. The method according to claim 1 , wherein the carbonating atmosphere is at ambient pressure and fans are used to provide draft and compensate a developed pressure drop.
8. The method according to claim 1 , wherein at least 80 wt.-% of the concrete fines are carbonated.
9. The method according to claim 2 , wherein the concrete fines are adjusted to a particle size distribution determined via sieving or laser granulometry with a d 90 ≤1.5 mm.
10. The method according to claim 3 , wherein the concrete fines are adjusted to a particle size distribution determined via sieving or laser granulometry with a d 90 ≤1 mm.
11. The method according to claim 1 , wherein the temperature is adjusted to a range from 3 to 6° C. above the water dew point.
12. The method according to claim 4 , wherein the temperature is adjusted to a range from 2 to 7° C. above the water dew point.
13. The method according to claim 6 , wherein the temperature is adjusted to a range from 2 to 7° C. above the water dew point.
14. The method according to claim 12 , wherein the ground and partially carbonated concrete fines are recirculated on average 10 to 100 times to the reactor and/or the mill.
15. The method according to claim 13 , wherein at least 95 wt.-%, of the concrete fines are carbonated.
16. A device for sequestering CO 2 and carbonation of concrete fines comprising a mill with separator adapted to receive a concrete fine feed and a gas containing from 10 to 99 Vol.-% CO 2 as carbonating atmosphere, a fluidized bed reactor connected to the mill and adapted to receive partially carbonated and ground concrete fines from the mill and the partially decarbonated gas for carbonation recirculation, and output means adapted to withdraw decarbonated gas and carbonated concrete fines and to recirculate the gas until it is decarbonated and to recirculate the concrete fines until they are carbonated to a desired degree.
17. The device according to claim 16 , additionally comprising a crusher with means for separating concrete fines from particles reusable as aggregate and foreign matter contained, for providing the concrete fines from concrete demolition waste.
18. The device according to claim 16 , wherein the output means are a fabric filter and a rotary valve or V-slot turning gate.
19. The device according to claim 16 , additionally comprising a water supply as cooling means for adjusting the temperature in the mill and/or reactor as well as the water content in the carbonating atmosphere.
20. The device according to claim 16 , additionally comprising a gas-to-gas heat exchanger and/or burner for adjusting the temperature of the carbonating atmosphere.
21. The device according to claim 16 , additionally comprising one or more induced draft fans to provide a gas flow in the device and/or to compensate a developed pressure drop.
22. The device according to claim 17 , wherein the output means are a fabric filter and a rotary valve or V-slot turning gate.
23. The device according to claim 22 , additionally comprising one or more of:
a water supply as cooling means for adjusting the temperature in the mill and/or reactor as well as the water content in the carbonating atmosphere,
a gas-to-gas heat exchanger and/or burner for adjusting the temperature of the carbonating atmosphere,
one or more induced draft fans to provide a gas flow in the device and/or to compensate a developed pressure drop.