CARBONATION OF METAL SILICATES FOR LONG-TERM CO2 SEQUESTRATION

• US 20080112868A1
• Filed: 01/17/2008
• Published: 05/15/2008
• Est. Priority Date: 04/23/2003
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Anovitz, Lawrence, Blencoe, James, Palmer, Donald, Beard, James
• Granted Patent: US 8,114,374 B2
• Time in Patent Office: Days
• US Class Current: 423/224
• CPC Class Codes: B01D 2251/30 Alkali metal compounds
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2258/02 Other waste gases
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: C01B 32/60 Preparation of carbonates or bicarbonates in general of percarbonates C01B15/10; of specific carbonates or bicarbonates according to the cation C01B-C01G
• CPC Class Codes: C01F 11/18 Carbonates
• CPC Class Codes: C01F 11/181 Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
• CPC Class Codes: C01F 5/24 Magnesium carbonates
• CPC Class Codes: C05D 5/00 Fertilisers containing magnesium C05D7/00 takes precedence
• CPC Class Codes: C05D 9/02 containing trace elements
• CPC Class Codes: C05G 3/80 Soil conditioners
• CPC Class Codes: C05G 5/30 Layered or coated, e.g. dust-preventing coatings
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02P 20/151 Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Claims

1-31. -31. (canceled)

32. A process of carbonating a metal silicate comprising the steps of:

reacting a metal silicate with a first caustic alkali-metal hydroxide to produce a metal hydroxide comprising metal from the metal silicate;

reacting the metal hydroxide with a source of carbon dioxide to produce a metal carbonate comprising metal from the metal hydroxide and to produce a reconstituted caustic material; and

introducing the reconstituted caustic material as the first caustic alkali-metal hydroxide in the step of reacting the metal silicate with the first caustic alkali-metal hydroxide to produce the metal hydroxide.

33. The process of claim 32, wherein the source of carbon dioxide is provided by reacting a second caustic alkali-metal hydroxide with carbon dioxide to provide an aqueous solution for the source of the carbon dioxide, wherein the second caustic alkali-metal hydroxide has a same or a different composition than the first caustic alkali-metal hydroxide.

34. The process of claim 32, wherein the first caustic alkali-metal hydroxide comprises an aqueous solution of NaOH, the metal silicate comprises CaSiO₃, the metal hydroxide comprises NaCaSiO₃(OH), the source of the carbon dioxide comprises Na₂CO₃, and the metal carbonate comprises CaCO₃.

35. The process of claim 32, wherein the first caustic alkali-metal hydroxide comprises an aqueous solution of NaOH, the metal silicate comprises CaAl₂Si₂O₈, the metal hydroxide comprises Ca(OH)₂, Na₈(AlSiO₄)₆(OH)₂, or a combination thereof, the source of the carbon dioxide comprises Na₂CO₃, and the metal carbonate comprises CaCO₃.

36. The process of claim 32, wherein the first caustic alkali-metal hydroxide comprises an aqueous solution of NaOH, the metal silicate comprises Mg₂SiO₄, Mg₃Si₂O₅(OH)₄, or a combination thereof, the metal hydroxide comprises Mg(OH)₂, the source of carbon dioxide comprises NaHCO₃, and the metal carbonate comprises MgCO₃.

37. The process of claim 36, wherein the reacting of the metal silicate with the first caustic alkali-metal hydroxide further produces Na₂SiO₃, wherein the source of carbon dioxide is provided by reacting the Na₂SiO₃ with the metal hydroxide to provide the source of carbon dioxide comprising NaHCO₃.

38. The process of claim 32, wherein the first caustic alkali-metal hydroxide comprises an aqueous solution of NaOH, the metal silicate comprises Fe₂SiO₄, the metal hydroxide comprises Fe(OH)₂, the source of carbon dioxide comprises NaHCO₃, and the metal carbonate comprises FeCO₃.

39. The process of claim 38, wherein the reacting of the metal silicate with the first caustic alkali-metal hydroxide further produces Na₂SiO₃, wherein the source of carbon dioxide is provided by reacting the Na₂SiO₃ with the metal hydroxide to provide the source of carbon dioxide comprising NaHCO₃.

40. A process of carbonating a metal silicate comprising the steps of:

(a) reacting the metal silicate with a first caustic material to produce a metal hydroxide comprising metal formerly contained in the metal silicate; and

(b) reacting the metal hydroxide with a source of carbon dioxide to produce a metal carbonate comprising metal formerly contained in the metal silicate of step (a).

41. A process according to claim 40 wherein the reaction of step (b) also produces a reconstituted caustic material, and wherein the process comprises an additional step (c) of introducing the reconstituted caustic material into step (a).

42. The process of claim 40, wherein the source of carbon dioxide is provided by reacting a second caustic material with at least one of the metal hydroxide, carbon dioxide, or a combination thereof.

43. The process of claim 40, wherein the reacting of the metal silicate with the first caustic material further produces an alkali metal silicate, wherein the source of carbon dioxide is provided by reacting the alkali metal silicate with the metal hydroxide to provide the source of carbon dioxide comprising alkali metal carbonate, alkali metal bicarbonate or a combination thereof.

44. A process of sequestering carbon dioxide comprising the steps of:

(a) reacting a metal silicate with a first caustic alkali-metal hydroxide to produce a metal hydroxide comprising metal formerly contained in the metal silicate;

(b) reacting carbon dioxide with at least one of a second caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and

(c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a metal carbonate comprising metal formerly contained in the metal silicate of step (a).

45. A process according to claim 44 wherein the reaction of step (c) further produces a reconstituted caustic alkali-metal hydroxide, and wherein the process further comprises an additional step (d) of recycling the reconstituted caustic alkali-metal hydroxide from step (c) into the reaction of step (a).

46. A process according to claim 44 wherein steps (b) and (c) are conducted at a pressure not greater than about 50 bars above the vapor pressure of pure water.

47. A process according to claim 44, wherein when the metal silicate is magnesium silicate the process produces at least one of magnesite and eitelite, or when the metal silicate is a calcium silicate the process produces calcite, or when the metal silicate is an iron-bearing silicate the process produces siderite.

48. A process according to claim 44, wherein the metal silicate comprises calcium silcates, magnesium silicates, iron-bearing silicates, or mixtures thereof, and at least one of the first caustic alkali-metal hydroxide and the second caustic alkali-metal hydroxide is comprised of sodium hydroxide, potassium hydroxide, lithium hydroxide, or a mixture thereof.

49. A process according to claim 44, further comprising reducing the particle size of the metal silicate to an average diameter of less than about two millimeters.

50. A process according to claim 44, wherein the process is conducted without heat pretreatment of the metal silicate.

51. A process of producing a metal carbonate comprising:

reacting an alkaline-earth metal hydroxide with at least one of an alkali-metal carbonate, an alkali-metal bicarbonate, and carbon dioxide, to produce a metal carbonate comprising metal formerly contained in the metal hydroxide.

52. A process of carbonating a metal silicate comprising:

reacting at least the metal silicate and a source of carbon dioxide to produce a

carbonate of the metal, wherein the reaction is conducted at a pressure not greater than about 50 bars above the vapor pressure of pure water for temperature of reaction.

53. A process according to claim 52 wherein the reaction is conducted at a pressure not greater than about 30 bars above the vapor pressure of pure water for the temperature of the reaction.