Method for carbon dioxide capture and sequestration using alkaline industrial wastes

1. A method of sequestering gaseous carbon dioxide, the method comprising:

(a) carbonating an oxide or hydroxide by contacting a material comprising the oxide or hydroxide with a first aqueous carbonate solution for a time, at a temperature, and under conditions wherein:

(i) at least a portion of the oxide or hydroxide is converted into a carbonate and wherein at least a portion of the carbonate so formed precipitates from the aqueous carbonate solution, to yield a precipitate; and

(ii) an aqueous hydroxide solution is formed; and

(b) contacting the aqueous hydroxide solution of step (a)(ii) with gaseous carbon dioxide for a time, at a temperature, and under conditions wherein at least a portion of the gaseous carbon dioxide is sequestered into a second aqueous carbonate solution.

2. The method of claim 1 , wherein the material comprising the oxide or hydroxide in step (a) comprises solid industrial waste.

3. The method of claim 2 , wherein the industrial waste is selected from the group consisting of fly ash, bottom ash, slag, and crushed concrete.

4. The method of claim 1 , further comprising using at least a portion of the second aqueous carbonate solution of step (b) as at least a portion of the first aqueous carbonate solution of step (a).

5. A method of sequestering gaseous carbon dioxide, the method comprising:

(a) carbonating an oxide or hydroxide by contacting a material comprising the oxide or hydroxide with a first aqueous carbonate solution for a time, at a temperature, and under conditions wherein:

(i) at least a portion of the oxide or hydroxide is converted into a carbonate and wherein at least a portion of the carbonate so formed precipitates from the aqueous carbonate solution to yield a precipitate; and

(ii) an aqueous hydroxide solution is formed;

(b) contacting the aqueous hydroxide solution of step (a)(ii) with gaseous carbon dioxide for a time, at a temperature, and under conditions wherein at least a portion of the gaseous carbon dioxide is sequestered into a second aqueous carbonate solution; and

(c) using at least a portion of the second aqueous carbonate solution of step (b) as at least a portion of the first aqueous carbonate solution of step (a).

6. The method of claim 5 , wherein the material comprising the oxide or hydroxide in step (a) comprises solid industrial waste.

7. The method of claim 6 , wherein the industrial waste is selected from the group consisting of fly ash, bottom ash, slag, and crushed concrete.

8. The method of claim 5 , wherein the first and second aqueous carbonate solutions comprise one or more water-soluble carbonates selected from the group consisting of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

9. The method of claim 5 , wherein the first and second aqueous carbonate solutions comprise one or more water-soluble carbonates selected from the group consisting of sodium carbonate and sodium bicarbonate, and the aqueous hydroxide solution formed in step (a)(ii) comprises sodium hydroxide.

10. The method of claim 5 , wherein the first and second aqueous carbonate solutions comprise one or more water-soluble carbonates selected from the group consisting of potassium carbonate and potassium bicarbonate, and the aqueous hydroxide solution formed in step (a)(ii) comprises potassium hydroxide.

11. The method of claim 5 , wherein in step (a), the first aqueous carbonate solution is saturated with carbonate.

12. The method of claim 5 , wherein in step (a), the aqueous carbonate solution has a carbonate concentration of from about 0.01 M to about 3.0 M carbonate.

13. The method of claim 5 , wherein step (a) comprises contacting the material comprising the oxide or hydroxide with the first aqueous carbonate solution for about 5 minutes to about 24 hours, at a temperature of about 20° C. to about 100° C., at a pressure of about 1 atmosphere.

14. The method of claim 5 , wherein the material comprising the oxide or hydroxide is bulk particulate matter having a mean particle diameter no larger than about 1 mm.

15. The method of claim 5 , wherein the material comprising the oxide or hydroxide is bulk particulate matter having a mean particle diameter no larger than about 100 micrometers.

16. The method of claim 5 , comprising contacting the material comprising the oxide or hydroxide with the first aqueous carbonate solution at a loading of from about 1 mL to about 500 mL first aqueous carbonate solution per gram material comprising the oxide.

17. The method of claim 5 , wherein the oxide or hydroxide of step (a) comprises calcium, and the precipitate of step (a)(i) comprises calcium carbonate, and further comprising:

(d) contacting the precipitate of step (a)(i) with water and gaseous carbon dioxide at a pressure above atmospheric pressure, for a time, and at a temperature where at least a portion of the calcium carbonate dissolves into the water to yield a solution comprising calcium carbonate.

18. The method of claim 17 , further comprising, after step (d):

(e) separating at least a portion of the solution comprising calcium carbonate from any remaining solids; and then

(f) reducing the pressure of the carbon dioxide to a level wherein calcium carbonate precipitates from the solution comprising calcium carbonate.

19. The method of claim 18 , wherein in step (d) the pressure of the carbon dioxide is from about 2 to about 10 atmospheres.

20. The method of claim 18 , wherein the temperature of step (d) is from about 10° C. to about 50° C.