Process for the removal of heavy metals from fluids

Abstract

A process for removal of heavy metals and/or dioxins from a fluid including heavy metals, where the fluid is brought in contact with a mixture including between 30% vol. and 60% vol. of an activated carbon catalyst impregnated with sulfur, between 30% vol. and 60% vol. of an activated carbon catalyst impregnated with iron and between 5% vol. and 40% vol. of a filler material, the total of these three ingredients being 100% vol, where the fluid is left in contact with the mixture, the heavy metals and/or dioxins are absorbed onto the mixture to obtain a fluid with a depleted level of heavy metals, which fluid is then evacuated from the mixture.

Claims

1. A process for the removal of heavy metals and/or dioxins from a fluid comprising heavy metals, the process comprising bringing the fluid in contact in a fixed-bed adsorber with a mixture comprising, based on a total volume of particles in the mixture, between 30% vol. and 60% vol. of separate, distinct particles of an activated carbon catalyst impregnated with sulfur, between 30% vol. and 60% vol. of separate, distinct particles of an activated carbon catalyst impregnated with iron, and between 5% vol. and 40% vol. of separate, distinct particles of a filler material, said particles of a filler material having a mean particle size, based on the average largest dimensionby numberof the particle, of more than 4 mm, leaving the fluid in contact with the mixture, allowing absorption of the heavy metals and/or dioxins onto the mixture to obtain a fluid with a depleted level of heavy metals and/or dioxins, and evacuating the fluid with a depleted level of heavy metals and/or dioxins from the mixture, wherein any individual particle of said activated carbon catalyst impregnated with sulfur is distinguishable from any individual particle of said activated carbon catalyst impregnated with iron at least on the basis of chemical composition.

2. The process as claimed in claim 1, wherein the fluid is a gas.

3. The process as claimed in claim 2, wherein the gas is a waste gas from sewage, sludge or hazardous waste incineration plants.

4. The process as claimed in claim 2, wherein the gas comprises at least 50 mg/dscm % weight of heavy metals and/or at least 200 ng/dscm of dioxins.

5. The process as claimed in claim 1, wherein the fluid is a liquid.

6. The process as claimed in claim 5, wherein the liquid comprises at least 40 mg/l of heavy metals and/or at least 0.02 g/1 of dioxins.

7. The process as claimed in claim 1, wherein the mixture comprises between 40% vol. and 50% vol. of the separate, distinct particles of activated carbon catalyst impregnated with sulfur, based on a total volume of particles in the mixture.

8. The process as claimed in claim 1, wherein the separate, distinct particles of activated carbon catalyst impregnated with sulfur comprises between 5% weight and 20% weight of sulfur, based on a total weight of the separate, distinct particles of activated carbon catalyst impregnated with sulfur.

9. The process as claimed in claim 1, wherein the mixture comprises between 40% vol. and 50% vol. of the separate, distinct particles of activated carbon catalyst impregnated with iron, based on a total volume of particles in the mixture.

10. The process as claimed in claim 1, wherein the separate, distinct particles of activated carbon catalyst impregnated with iron comprises between 10% weight and 30% weight of iron, based on a total weight of the separate, distinct particles of activated carbon catalyst impregnated with iron.

11. The process as claimed in claim 1, wherein the filler material comprises at least one of plastic, alumina and ceramic.

12. The process as claimed in claim 1, wherein the separate, distinct particles of filler material comprise a free volume of 50% vol and 97% vol, based on a total volume of the filler material.

13. The process as claimed in claim 1, wherein the separate, distinct particles of filler material are present in an amount from 5 to 15% vol, based on a total volume of particles in the mixture.

14. The process as claimed in claim 1, wherein the filler material is a shape comprising at least one of saddle shaped, ring shaped, ball shaped, torus shaped, prism shaped and irregular shaped.

15. The process as claimed in claim 2, wherein the gas is conditioned in at least one of a coalescer, a droplet separator and a heat exchanger before it is put in contact with the mixture.

Description

DETAILED DESCRIPTION

(1) Further details and advantages of the present disclosure will be apparent from the following detailed description of several not limiting embodiments.

Test 1Removal from GasPlant Scale

(2) Emission sampling during two days was performed at the outlet of the Kombisorbon process reactor, filled with a specific activated carbon mixture: 45% of activated carbon impregnated with sulfur supplied from Jacobi Carbons, 45% of activated carbon impregnated with iron supplied from Watch-Water, and 10% of a plastic filler material.

(3) The removal rate of cadmium was 99.9%, for mercury more than 99.9% and more than 99.9% removal rate for dioxins. The initial levels were 5 mg/dscm for cadmium, 1 mg/dscm for mercury and 350 ng/dscm for dioxins.

(4) The presence of activated carbon mixture and filler material allowed a better gas flow distribution and subsequently the cleaning of a higher concentrated inlet gas due to an increased removal rate of contaminants.

(5) The presence of filler allowed a more efficient washing of the activated carbon with sulfates removal coming from the reaction between SOx and NOx with water vapors from inlet flue gas.

(6) The presence of filler allowed a quicker drying step after regeneration with water flow.

Test 1-b Comparative ExampleRemoval from GasPlant Scale

(7) Emission sampling during two days was performed at the outlet of the Kombisorbon process reactor, filled with a 100% of activated carbon impregnated with sulfur supplied from Jacobi Carbons.

(8) The removal rate of cadmium was 99%, for Mercury, more than 99% and more than 99% removal rate for dioxins. The initial levels were 5 mg/dscm for cadmium, 1 mg/dscm for mercury and 350 ng/dscm for dioxins.

Test 2Removal from LiquidLaboratory ScaleSingle Pass

(9) 500 cm.sup.3 of a mixture: 30% of activated carbon catalyst impregnated with sulfur supplied from Jacobi Carbons, 30% of activated carbon impregnated with iron supplied from Watch-Water, 40% of a plastic filler material was used during this test.

(10) The level of heavy metals in a phosphoric acid solution was reduced significantly. 20% removal rate for cadmium and mercury and 35% removal rate for arsenic.

Test 3Removal from LiquidLaboratory ScaleSingle Pass

(11) 500 cm.sup.3 of a mixture of 45% of activated carbon impregnated with sulfur, 45% of activated carbon impregnated with iron supplied from Watch-Water, and 10% of a plastic filler material was used during this test.

(12) The level of heavy metals in a phosphoric acid solution was reduced significantly. 75% removal for cadmium and mercury and 65% removal for arsenic. The initial concentrations were 39 ppm for cadmium, 0.1 ppm for mercury and 23 ppm for arsenic.

(13) The presence of filler material allowed less clogging from silica coming from the phosphoric acid media inside the activated carbon bed.

(14) The presence of filler material allowed a more efficient washing of the activated carbon with easier silica removal.

Test 3-bComparative ExampleRemoval from LiquidLaboratory ScaleSingle Pass

(15) 500 cm.sup.3 of 100% of activated carbon impregnated with sulfur supplied from Jacobi Carbons was used during this test.

(16) The level of heavy metals in a phosphoric acid solution (As: 23 ppm, Hg: 0.1 ppm and Cd: 39 ppm) was reduced. Only a 20% removal rate for mercury and only 35% removal rate for arsenic were achieved.

Test 3-cComparative ExampleRemoval from LiquidLaboratory Scale Single Pass

(17) 500 cm.sup.3 of 100% of activated carbon catalyst impregnated with iron supplied from Watch-Water was used during this test.

(18) The level of heavy metals in a phosphoric acid solution (As: 23 ppm, Hg: 0.1 ppm and Cd: 39 ppm) was reduced. Only a 50% removal rate for cadmium and mercury and only a 15% removal rate for arsenic were achieved.

(19) The activated carbon used in the tests above had a specific high catalytic surface area (BET at least 700 m.sup.2/g) with impregnation (like Br, Cu, Fe, S, OH . . . ).

(20) The activated carbon was mixed with various types of filler materials of different shapes (cylinder, balls, Sattelkrper, . . . ) and different material (plastic, alumina, ceramic, . . . ) in various ratios (1/5; 1/3; 1/10; . . . ). Different suppliers of activated carbon catalysts for companies like Jacobi, Cabot Carbon, Chemviron, Desotec, Carbotech and ATEC were tested.

(21) It must be noted that the active carbon catalysts do not contain: a. any iodine, bromine or a compound thereof, b. any water repellent, c. any catalytically active metals such as Platinum, Palladium, Rhodium etc. or, d. any organic/catalytically active metal complexes based on metals such as Platinum, Palladium, Rhodium etc.

(22) The active carbon catalyst is not hydrophobized by means of hydrophobic polymer compounds such as polytetrafluoroethylene, polyisobutylene, polyethylene, polypropylene or polytrichlorfluorethylen.

(23) Although the present disclosure has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

(24) All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.