Method for the removal of mercury from a gas stream

• US 20030103882A1
• Filed: 10/22/2002
• Published: 06/05/2003
• Est. Priority Date: 01/26/2001
• Status: Active Grant

• Current Assignee: Minplus Holding BV
• Original Assignee: Minplus Holding BV
• Inventors: Voogt, Nicolaas, Biermann, Joseph Jan
• Granted Patent: US 6,974,564 B2
• Time in Patent Office: Days
• US Class Current: 423/210
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• 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 20/12 Naturally occurring clays or bleaching earth
• CPC Class Codes: B01J 20/16 Alumino-silicates B01J20/12 takes precedence
• CPC Class Codes: B01J 20/3078 Thermal treatment, e.g. calcining or pyrolizing
• 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 2220/4831 having been subjected to further processing, e.g. paper, cellulose pulp

Abstract

The present invention relates to a method for the removal of mercury from a gas stream. The method is characterized in that at a temperature above 170° C. the gas stream is contacted with a sorbent that as the active component is comprised of a mixture of substantially silica-alumina compounds and/or calcium compounds. According to a preference, the sorbent is kaolin, that may or may not be in the dehydrated form of meta-kaolin and is optionally obtained by thermal conversion of a material chosen from paper waste or residue from the paper industry. By this method it is possible to remove mercury at temperatures higher than room temperature.

The invention also relates to a method for the removal of mercury from a gas stream, wherein the gas stream is contacted with a sorbent at a temperature above 50° C., which sorbent comprises as active substance a mixture of substantially silica-alumina compounds and/or calcium compounds, as well as with an oxidator. The invention also relates to a mercury-comprising sorbent obtained by this method and products manufactured therewith.

Claims

1. A method for the removal of mercury from a gas stream, characterized in that at a temperature above 170°

C. the gas stream is contacted with a sorbent that as the active component is comprised of a mixture of substantially silica-alumina compounds and/or calcium compounds.

2. A method according to claim 1, characterized in that the sorbent comprises kaolin, that may or may not be in the dehydrated form of meta-kaolin.

3. A method according to claim 1 or 2, characterized in that the calcium compounds comprise calcium carbonate and/or calcium oxide, preferably 60-70% of calcium carbonate and 40-30% of calcium oxide.

4. A method according to one of the preceding claims, characterized in that the sorbent is obtained by thermal conversion of a material chosen from 1. paper waste and 2. residue from the paper production.

5. A method according to one of the preceding claims, characterized in that during sorption the temperature is higher than 230°

C., preferably higher than 300°

C., more preferably higher than 450°

C., still more preferably higher than 550°

C.

6. A method according to one of the preceding claims, characterized in that the same comprises the step of activating the sorbent by means of an oxidator chosen from, for example, sulphate compounds, peroxides or chloride compounds.

7. A method according to claim 6, characterized in that the activation of the sorbent and the oxidator is carried out prior to contacting the sorbent with the gas stream to be cleaned.

8. A method according to claim 7, characterized in that after activation of the sorbent, the oxidator is removed.

9. A method according to one of the claims 6 to 8, characterized in that the oxidator and the sorbent are mixed together and as mixture added to the gas stream to be cleaned.

10. A method according to one of the claims 6 to 8, characterized in that the oxidator is added earlier to the gas stream, upstream from the sorbent.

11. A method according to one of the claims 6 to 10, characterized in that as oxidator a chlorine compound, preferably calcium hypochlorite is used.

12. A method according to one of the claims 6 to 10, characterized in that during sorption the temperature is higher than 50°

C., preferably higher than 100°

C., more preferably higher than 200°

C., still more preferably higher than 300°

C., and most preferably higher than 400°

C.

13. A method according to one of the preceding claims, characterized in that the mercury is present in the metallic form.

14. A sorbent, characterized in that it comprises mercury adsorbed thereto, obtained by a method according to one of the preceding claims.

15. A sorbent according to claim 14, characterized in that up to temperatures of more than 900°

C. the mercury is irreversibly bound to the sorbent.

16. Use of the mercury-comprising sorbent according to claim 14 or 15 in a binding agent as hydraulic or pozzolanic compound.

17. A moulded product obtained by using a sorbent according to claim 14 or 15.

18. A method of improving a sorbent for the removal of mercury from a gas stream, characterized in that the same comprises steps of activating a compound comprised of a mixture of substantially silica-alumina compounds and/or calcium compounds, with an oxidator chosen from, for example, sulphate compounds, peroxides or chlorine compounds.