Highly reactive reagents and compositions for purifying exhaust gases and wastewater, production and use thereof

• US 5,502,021 A
• Filed: 06/07/1995
• Issued: 03/26/1996
• Est. Priority Date: 10/29/1990
• Status: Expired due to Term

• Current Assignee: Walhalla-Kalk Entwicklungs-Und Vertriebsgesellschaft
• Original Assignee: Walhalla-Kalk Entwicklungs-Und Vertriebsgesellschaft
• Inventors: Schuster, Georg
• Primary Examiner(s): GIBSON, SHARON A
• Application Number:
  US08/480,029
• Time in Patent Office: 293 Days
• Field of Search: 502/400, 423/210, 423/220, 423/228, 423/635, 423/640, 253/378 R
• US Class Current: 502/400
• CPC Class Codes: B01D 53/64 Heavy metals or compounds thereof, e.g. mercury
• CPC Class Codes: B01D 53/68 Halogens or halogen compounds
• CPC Class Codes: B01D 53/72 Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
• CPC Class Codes: B01J 20/041 Oxides or hydroxides
• CPC Class Codes: B01J 20/045 containing sulfur, e.g. sulfates, thiosulfates, gypsum
• CPC Class Codes: B01J 20/12 Naturally occurring clays or bleaching earth
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• 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: C04B 2/06 with addition of substances, e.g. hydrophobic agents ; Slaking in the presence of other compounds

Abstract

This invention concerns highly reactive reagents and compositions for purifying exhaust gases and flue gases and for purifying wastewater as well as the processes for producing same and use thereof.

The reagents and compositions are mixtures of calcium hydroxide with additives, especially clays, powdered bricks, carbon products such as coal dust and flue ash and optionally water glass which are already porous due to their special production and have a high specific surface area of up to about 200 m² /g.

Using these sorbents, hydrocarbons and halogenated hydrocarbons, dioxins and furans in addition to heavy metals can be removed from exhaust gases and wastewater. Other advantages include the easy setup of the resulting products and their great safety for dumping.

Claims

1. Highly reactive reagents for purifying exhaust gases and flue gases, especially from combustion processes, and wastewater with the same or similar pollutants as in the exhaust gases based on mixtures of calcium hydroxide with additives, characterized by:

a mixture of

(a) dry slaked lime with porous ground clay as additive;

or

(b) dry foamed slaked lime with ground clay as additive;

wherein the mixture contains about 60 to 99 wt. percent of slaked lime, based on dry weight.

2. The reagents according to claim 1, characterized in that they have a specific surface area of about 25 to 100 m² /g.

3. The reagents according to either claim 1 or 2, characterized in that they contain a bentonite as clay.

4. The reagents according to either claim 1 or 2, characterized in that they contain as further additives burnt clay, expanded concrete dust, perlites, expanded clay, limestone brick powder, trass powder, trass lime, bleaching earth, cement, calcium aluminate, sodium aluminate, calcium sulfide, organic sulfides, calcium sulfite, calcium sulfate, blast furnace coke, lignite dust, activated carbon, flue ash, water glass, accelerators and/or retarders (selected from pore-forming substances Addiment LP1. LP2, 1TM).

5. The reagents according to either claim 1 or 2, characterized in that they contain one or more additives in the amount of about 1 to 40 wt. %, based on dry weight.

6. The reagents according to either claim 1 or 2, characterized in that they contain one or more additives in the amount of about 1 to 15 wt. % based on dry weight.

7. The reagents according to either claim 1 or 2, characterized by about 80 to 90 wt. % calcium hydroxide, about 2 to 20 wt. % clay and 0.1 to 1 wt. % calcium sulfide, based on dry weight, where the total weight of these components is 100 wt. %.

8. A process for producing highly reactive reagents for purifying exhaust gases and flue gases, especially from combustion processes, and wastewater with the same or similar pollutants as in the exhaust gases based on mixtures of calcium hydroxide with additives, especially according to either claim 1 or 2, characterized by:

mixing

(a) dry slaked lime with porous ground clay as additive;

or

(b) dry throned slaked lime with ground clay as additive;

in such amounts that the resulting product contains about 60 to 99 wt. % slaked lime.

9. The process according to claim 8, characterized in that bentonites are used as clays.

10. The process according to claim 8, characterized in that a slaked lime is used which has been produced by using a foaming agent.

11. The process according to claim 8, characterized in that burnt clay, expanded concrete dust, perlite, bulked clay, limestone, brick powder, trass powder, trass lime, bleaching earth, cement, calcium aluminate, sodium aluminate, calcium sulfide, organic sulfides, calcium sulfite, calcium sulfate, carbon-containing sorbents such as especially blast furnace coke, lignite dust, activated carbon and flue ash as well as water glass, accelerators and/or retarding agents are used as further additives (selected from pore-forming substances Addiment LP1, LP2, 1TM).

12. The process according to claim 9, characterized in that burnt clay, expanded concrete dust, perlite, bulked clay, limestone, brick powder, trass powder, trass lime, bleaching earth, cement, calcium aluminate, sodium aluminate, calcium sulfide, organic sulfides, calcium sulfite, calcium sulfate, carbon-containing sorbents such as especially blast furnace coke, lignite dust, activated carbon and flue ash as well as water glass, accelerators and/or retarding agents are used as further additives (selected from pore-forming substances Addiment LP1, LP2, 1TM).

13. The process according to claim 10, characterized in that burnt clay, expanded concrete dust, perlite, bulked clay, limestone, brick powder, trass powder, trass lime, bleaching earth, cement, calcium aluminate, sodium aluminate, calcium sulfide, organic sulfides, calcium sulfite, calcium sulfate, carbon-containing sorbents such as especially blast furnace coke, lignite dust, activated carbon and flue ash as well as water glass, accelerators and/or retarding agents are used as further additives (selected from pore-forming substances Addiment LP1, LP2, 1TM).

14. The process according to claim 8, characterized in that the additives are used in amounts such that the resulting product contains about 1 to 40 wt. % additives, based on dry weight.

15. The process according to claim 11, characterized in that the additives are used in amounts such that the resulting product contains about 1 to 40 wt. % additives, based on dry weight.

16. The process according to claim 14, characterized in that the additives are used in amounts such that the resulting product contains about 1 to 15 wt. % additives, based on dry weight.

17. The process according to either claim 8, characterized in that the type and amounts of additives used are selected so that the resulting product contains about 80 to 90 wt. % calcium hydroxide, about 2 to 20 wt. % clay and 0.1 to 1 wt. % calcium sulfide, based on dry weight, where the total weight of these components is 100 wt. %.