Solid Mineral Composition, Method for Preparing Same and Use Thereof for Reducing Heavy Metals in Flue Gas

• US 20120167762A1
• Filed: 07/13/2010
• Published: 07/05/2012
• Est. Priority Date: 07/13/2009
• Status: Active Grant

• Current Assignee: S. A. Lhoist Recherche et Developpement (Lhoist SA), Université de Liège
• Original Assignee: Université de Liège
• Inventors: Brasseur, Alain, Pirard, Jean-Paul, Laudet, Alain
• Granted Patent: US 8,871,006 B2
• Time in Patent Office: Days
• US Class Current: 95/134
• CPC Class Codes: B01D 2251/306 of potassium
• CPC Class Codes: B01D 2251/402 of magnesium
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 2251/606 Carbonates
• CPC Class Codes: B01D 2257/602 Mercury or mercury compounds
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/043 Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite
• CPC Class Codes: B01J 20/046 containing halogens, e.g. halides
• CPC Class Codes: B01J 20/165 Natural alumino-silicates, e.g. zeolites
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/3078 Thermal treatment, e.g. calcining or pyrolizing
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3236 containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 2220/56 Use in the form of a bed

Abstract

The invention relates to a solid mineral composition of heavy metals, in particular mercury, in flue gas, to a method for preparing such a solid mineral compound and to the use thereof for reducing heavy metals, in particular mercury, in flue gas, by placing the flue gas in contact with the solid mineral composition.

Claims

1. A solid composition for reducing heavy metals in flue gases comprising a mineral compound, preferably non-functionalized, doped with a halide salt, i.e., for which the surface accessible to flue gases is partly or completely covered with a halide salt, said mineral compound being selected from the group consisting of halloysite, calcium or magnesium carbonates or hydroxides, and sodium carbonates as well as of mixtures and derivatives thereof.

2. The composition according to claim 1, wherein said halide salt is an inorganic halide salt.

3. The composition according to claim 1, wherein said mineral compound is preferably selected from the group consisting of halloysite, slaked lime, dolomite and limestone as well as mixtures thereof.

4. The composition according to claim 1, wherein said halide salt is present in an amount on a dry basis ranging from 0.5% to 20% by weight, preferably from 1% to 15% by weight and in particular from 1.5% to 10% by weight of halide salt on the basis of the weight of the composition.

5. The composition according to claim 1, wherein said halide salt is an alkaline halide, an alkaline-earth halide or the like, preferably selected from the group consisting of NaCl, NaBr, NaI, KCl, KBr, KI, CaCl₂, CaBr₂, CaI₂, MgCl₂, MgBr₂, MgI₂, NH₄Cl, NH₄Br or NH₄I or mixtures thereof.

6. The composition according to claim 1, wherein the mineral compound is in powdery form and has a d₉₀ of less than 1 mm and in particular a particle size comprised between 1 μ

m and 1 mm.

17. The use of the composition according to claim 1, for reducing heavy metals, preferably in the gas state, in particular mercury and most particularly metallic mercury Hg⁰ in flue gases.

18. The use according to claim 17, with another solid material, in particular a mixture with a basic agent such as lime.

19. The use according to claim 17, wherein said doped mineral compound is put into contact with the flue gases at a temperature ranging from 70 to 350°

C., notably between 110 and 300°

C. and preferably between 120 and 250°

C.

7. A method for preparing a composition for reducing heavy minerals in flue gases comprising the steps:

supplying a mineral compound selected from the group consisting of halloysite, calcium or magnesium carbonates or hydroxides and sodium carbonates as well as mixtures thereof,

supplying a halide salt, and

putting into contact said mineral compound and said halide salt with formation of a mineral compound doped with the halide salt.

8. The method according to claim 7, wherein said putting into contact of said mineral compound and of said halide salt is achieved with stirring.

9. The method according to claim 7 wherein said supplied mineral compound has a humidity comprised between 0.1 and 100 g/kg, advantageously between 2 and 90 g/kg.

10. The method according to claim 7, wherein said putting into contact is carried out at room temperature.

11. The method according to claim 7, wherein said halide salt is in liquid form, in an aqueous phase.

12. The method according to claim 7, wherein said step for putting into contact said mineral compound and said halide salt is spraying of said halide salt on said mineral compound.

13. The method according to claim 7, wherein said step for putting into contact said mineral compound and said halide salt is soaking of said mineral compound in said halide salt in a liquid phase.

14. The method according to claim 11 wherein said halide salt in a liquid phase is either an solution aqueous or not, having a halide salt content comprised between 1% and the salt saturation of the solution, notably between 1% and 35%, preferably between 5% and 27% by weight based on the total weight of said solution.

15. The method according to claim 7, further comprising a step for drying and/or deagglomerating said mineral compound doped with the halide salt, preferably at a temperature comprised between 60 and 200°

C., in particular between 75 and 170°

C.

16. The method according to claim 7, wherein said halide salt is an alkaline halide, an alkaline-earth halide or the like, preferably selected from the group consisting of NaCl, NaBr, NaI, KCl, KBr, KI, CaCl₂, CaBr₂, CaI₂, MgCl₂, MgBr₂, MgI₂, NH₄Cl, NH₄Br or NH₄I or mixtures thereof.