WO2010009803A1 - Procédé de dépôt de mercure respectivement de ses composés, à partir de flux d'air vicié - Google Patents

Procédé de dépôt de mercure respectivement de ses composés, à partir de flux d'air vicié Download PDF

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Publication number
WO2010009803A1
WO2010009803A1 PCT/EP2009/004831 EP2009004831W WO2010009803A1 WO 2010009803 A1 WO2010009803 A1 WO 2010009803A1 EP 2009004831 W EP2009004831 W EP 2009004831W WO 2010009803 A1 WO2010009803 A1 WO 2010009803A1
Authority
WO
WIPO (PCT)
Prior art keywords
mercury
concentration
halogen
exhaust air
halide
Prior art date
Application number
PCT/EP2009/004831
Other languages
German (de)
English (en)
Inventor
Rico Kanefke
Uwe Listner
Volker Damrath
Original Assignee
Currenta Gmbh & Co. Ohg
Bayer Materialscience Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Currenta Gmbh & Co. Ohg, Bayer Materialscience Ag filed Critical Currenta Gmbh & Co. Ohg
Publication of WO2010009803A1 publication Critical patent/WO2010009803A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/64—Heavy metals or compounds thereof, e.g. mercury
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/60—Heavy metals or heavy metal compounds
    • B01D2257/602—Mercury or mercury compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2215/00—Preventing emissions
    • F23J2215/60—Heavy metals; Compounds thereof

Definitions

  • the present invention relates to a method for the separation of elemental mercury and mercury compounds from various process or Kunststoffa, especially from the chlorine-alkali electrolysis.
  • Exhaling processes or rooms or halls may contain mercury and / or its compounds through direct or indirect handling in the production process. This is the case, for example, in the chlor-alkali electrolysis according to the amalgam method or in dental laboratories. Depending on the underlying process, these flash offs can occur as point sources or as diffuse sources and also contain amounts of other constituents.
  • the mercury pollution in the air results in an increased mercury pollution for persons staying in it.
  • the mercury levels are usually not so high that acute poisoning occurs.
  • mercury also has a chronic toxic effect. Once absorbed into the body, it remains there for a long time, i. it is accumulated.
  • occupational exposure limits are prescribed in many countries, and due to the accumulation of even the smallest quantities in the body, a minimization requirement should be better applied - similar to that for carcinogenic substances.
  • the air To lower the mercury concentration in the room air, the air must either be directly sucked off and cleaned at a point source, or a sufficiently large air change must be realized in the entire room.
  • the extracted mercury-containing air must be cleaned before discharge into the environment, since for example in the TA Heil in Germany a minimization requirement according to the prior art is given. Currently, this cleaning is usually done by Aktivkohlef ⁇ lter. In particular, in large exhaust air streams and in the case of elemental mercury large apparatuses are required for this because of poor adsorbability, which lead to high operating costs.
  • H. Braun et al. (Chem.-Ing.-Techn. 60 (1988) No. 2, p. 135) report that, despite oxidation and precipitation of the resulting HgCl 2 in a wet scrubber, there are still high levels of elemental (metallic) mercury in the clean gas. In the wet scrubber, however, the absorbed mercury is present as slightly soluble HgCl 2 . H. Braun et al. Therefore, these results lead to dissolved sulfur dioxide in the wash water, which leads to the formation of Hg (I) and subsequently disproportionates to Hg (U) and Hg (0). H. Braun et al. propose an improvement in the separation of mercury from flue gases of waste incineration by means of a venturi scrubber. In addition of oxidizing substances in the flue gas scrubbing water should cause a significant reduction of the metallic discharge.
  • H. Braun et al. also teach "Other measures to optimize the operation of the scrubber, such as changes in differential pressure (1), Flue gas / Vapor ratio (2), pH (3), chloride content (4) and temperature reduction (5) do not lead to even better mercury reduction ".
  • the present invention is therefore based on the object to provide a method for reliable removal of mercury compounds available, which ensures the lowest or lowest operating costs and significantly reduced amounts of waste the same or better deposition of mercury than the prior art.
  • the present invention therefore provides a process for the separation of elemental mercury [Hg (el) or Hg (O)] and mercury compounds from exhaust air, comprising the following steps:
  • Hg (el) -containing exhaust air can take place directly at the emission source or from the room containing this emission source.
  • the Hg (el) -containing exhaust air (All) is first sucked off, for example, by means of a suction draft (3) and fed to a reaction chamber (1).
  • the mercury gets through by little Concentrations of gaseous halogen, preferably bromine or chlorine or a mixture thereof, more preferably chlorine at temperatures of less than 500 0 C, preferably at temperatures of 20 0 C to 100 0 C, in water-soluble mercury (II) halides, in particular mercury (II) chloride converted according to equation [I].
  • the addition of the gaseous halide is adjusted to the Hg (el) concentration and controlled automatically and / or continuously.
  • the Hg (el) concentration is already in the Hg (el) -containing exhaust air stream (All), i. before addition of halogen in the reaction chamber (1), measured by means of a measuring device.
  • continuous measuring devices such as e.g. the Hg-Monitor 3000 from Seefelder Messtechnik GmbH or Mercury Vapor Monitor VM 3000 from Mercury Instruments GmbH.
  • a mass ratio of halogen to mercury of 0.35 to 10,000, preferably 20 to 500, particularly preferably 20 to 100 is usually used. If the halogen is added in large excess, it does not adversely affect the oxidation, but this should be avoided for cost reasons.
  • the extracted amount of exhaust air can also be varied in order to achieve the desired exhaust air concentration in the space to be extracted.
  • the suctioned volume flow is adjusted on the basis of predetermined upper and lower limit values in the space to be suctioned off. If the value in the room to be extracted exceeds the upper limit value, the exhaust air volume flow is increased to comply with the specifications. In return, falls below the lower limit, the Suction - also for reasons of energy saving - throttled.
  • the lower and upper limits can also be identical. This ensures a constant Hg concentration and may even turn off the ventilation of the room to be extracted if the Hg concentration in the exhaust air is less than the limit.
  • the space to be extracted is normally vented with a continuous exhaust air flow (constant air exchange rate), which is temporarily increased with increased Hg concentration in the room to be extracted.
  • the reaction chamber (1) leaves an exhaust air stream containing oxidized mercury (for example HgCl 2 ) (A12).
  • This exhaust air stream A12 also still contains residues of the added halogen (for example chlorine), since this is preferably added in excess.
  • downstream scrubber unit (2) of the exhaust air stream A12 is simultaneously freed of excess halogen and mercury (II) halide.
  • a scrubber unit or wet scrubber in particular a packed column scrubber is advantageous because of its low operating costs and good separation efficiency.
  • the wash solution present in the scrubber unit contains one or more halides, in particular chlorides and / or bromides, and at least one reducing agent.
  • Divalent mercury halides are physically dissolved in water and have a vapor pressure over the solution. This vapor pressure limits the minimum achievable Hg concentration in the withdrawing clean gas flow (A13). This vapor pressure is lowered significantly when complexing occurs in the wash solution of mercury takes place.
  • the complexation is carried out, for example, and preferably by halides (preferably bromides or chlorides). Suitable sources of these halides are all customary salts, in particular sodium chloride and sodium bromide
  • the temperature of the washing solution is usually in the range from 4 to 90 ° C., preferably from 10 to 30 ° C., more preferably at room temperature or in open-air conditions at ambient temperature (but frost-free).
  • the resulting Hg are indicated concentrations of the pure gas in Figure 3 for the system HgCl 2 / Cl- / H 2 O and 30 0 C scrubber temperature.
  • the chloride concentration is usually more than 35 g / L, preferably more than 50 g / L.
  • the chloride concentration should therefore preferably be controlled to a constant high value as a function of the specifications.
  • the chloride concentration can be determined either via a chloride-selective electrode or via a combined conductivity and pH measurement in the solution, cf. Measurement QIA in Figure 1 and Figure 4. The values determined here are the
  • a fresh water addition (P3) and wastewater discharge (P6), as well as an addition of possibly missing chloride in the form of a NaCl solution addition (P5) are used.
  • the excess of halogen, in particular chlorine, introduced in the reaction chamber is deposited. This is done by reducing the halogen with at least one reducing agent present in the washing solution.
  • reducing agent present in the washing solution.
  • all known soluble reducing agents are suitable. Particularly preferred is sodium thiosulfate.
  • the sodium thiosulfate addition (P3) is also controlled automatically
  • sodium hydroxide solution P4
  • P4 sodium hydroxide solution
  • the pH is usually maintained in the range of 5-8.
  • the mercury-containing wastewater (P6) can be introduced into a downstream wash water treatment or treatment plant, where it is freed, for example by precipitation of mercury.
  • the mercury filter cake is usually deposited underground, with the volume and mass of the waste only 2-5% of the amount of waste, which is obtained in an activated carbon filter is.
  • the discharged into the environment exhaust air (withdrawing clean gas) (A13) is preferably monitored by a continuous mercury meter and a continuous chlorine meter, which - integrated for Störssennkompensation in the scrubber control - in case of breakdowns of mercury or chlorine due to e.g. sudden changes in concentration adjust the scrubber parameters.
  • Figure 1 shows the exemplary structure of the deposition process according to the invention in the form of an R + I scheme. From the continuous measuring systems, control lines run to the corresponding actuators (control valves for addition and wastewater discharge and the room air blower). Reference numerals:
  • A12 exhaust air stream (Hg (ox) -containing, in particular HgCl 2 -containing)
  • FIG. 1 shows the function for complete oxidation of elemental mercury by chlorine (Cl 2 ). In order to achieve a complete oxidation of elemental mercury, depending on the Hg (el) concentration, various excesses of chlorine are necessary. The control function is indicated.
  • Figure 3 shows a state diagram for the clean gas concentration (calculated according to the empirically determined equation 2) for the scrubber system HgC12 / chloride / H2O is applied at a scrubber temperature of 30 0 C.
  • the Hg (II) concentration in the exhaust air flow (A13) ( Ordinate) as a function of the chloride concentration in the scrubber (abscissa).
  • the clean gas concentration in the exhaust air stream A13 decreases.
  • the clean gas concentration is also dependent on the concentration of dissolved mercury (Hg ( ⁇ ) aq) contained in the scrubber cycle. This is regulated by the fresh water addition (P2) and the wastewater discharge (P6). The higher the dissolved mercury concentration, the higher the concentration in the evacuating clean gas of the exhaust air stream A13.
  • FIG. 4 shows the conductivity of a solution as a function of the chloride content in mol / l. It is irrelevant whether the chloride concentration results from sodium chloride, calcium chloride or from an aqueous hydrochloric acid solution.
  • One mole of chloride in one liter of water has a conductivity of 76.374 mS / cm. With commercially available conductivity probes, however, only the conductivity of the entirety of the ions can be measured.
  • the other ions eg Na +, Ca 2+ , H 3 O + , OH
  • DURAG / Verewa determined and forwarded to control the addition of chlorine in the reaction chamber to a mass flow controller.
  • a mass flow controller At an excess of 167 ⁇ g C12 / ⁇ gHg, complete oxidation of Hg in the reaction chamber was achieved. Complete chlorination was also achieved for all excesses> 167 ⁇ g C12 / ⁇ gHg.
  • the mercury (H) halide-containing exhaust air stream was introduced into a scrubber unit downstream of the reaction chamber into a halide-containing scrubbing solution (consisting of NaCl, sodium thiosulfate 5 g / l, water at room temperature).
  • a halide-containing scrubbing solution consisting of NaCl, sodium thiosulfate 5 g / l, water at room temperature.
  • the pH was maintained at 7-8 with dilute sodium hydroxide solution (5%).
  • the chloride concentration of the washing solution was determined by means of a chloride-selective measuring probe from IRAS, Hermsdorf and adjusted to 50 g / l by automatically controlled addition of a 3 molar NaCl solution into the washing solution.
  • the optimal complexation of Hg (H) was achieved from a concentration of 50 g / l chloride.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treating Waste Gases (AREA)

Abstract

La présente invention concerne un procédé de dépôt de mercure élémentaire et de composés du mercure provenant de différents flux d'air vicié de procédé ou de locaux, en particulier de l'électrolyse chlore-alcali. Ce procédé comporte les étapes suivantes : a) amenée d'un flux d'air vicié contenant du mercure dans une chambre de réaction, b) oxydation de l'espèce mercure élémentaire dans le flux d'air vicié amené par au moins un halogène gazeux avec formation d'halogénures de mercure-(II), c) séparation des halogénures de mercure (II) formés à partir de flux d'air vicié oxydé formé à l'étape b), dans une unité de lavage avec élimination simultanée de restes de l'halogène gazeux utilisé pour l'oxydation et en présence d'un agent réducteur comme le thiosulfate de sodium, et d) évacuation du flux d'air vicié et des eaux résiduaires contenant du mercure.
PCT/EP2009/004831 2008-07-19 2009-07-04 Procédé de dépôt de mercure respectivement de ses composés, à partir de flux d'air vicié WO2010009803A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008033835.4 2008-07-19
DE102008033835 2008-07-19

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WO2010009803A1 true WO2010009803A1 (fr) 2010-01-28

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4729882A (en) * 1985-03-28 1988-03-08 Tokyo Metropolitan Environmental Service Corporation Process for cleaning mercury-containing gaseous emissions
DE4422661A1 (de) * 1994-06-28 1996-01-04 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Verfahren und Anordnung zur kontinuierlichen Abtrennung von Quecksilber aus strömenden Gasen
US6447740B1 (en) * 1998-05-08 2002-09-10 Isca Management Ltd. Mercury removal from flue gas
DE10233173A1 (de) * 2002-07-22 2004-02-12 Bayer Ag Verfahren zur Abscheidung von Quecksilber aus Rauchgasen
US20070053827A1 (en) * 2003-08-12 2007-03-08 Outokumpu Technology Oy Method for the removal of mercury from sulphuric acid with thiosulphate precipitation
WO2009092575A1 (fr) * 2008-01-23 2009-07-30 Vosteen Consulting Gmbh Procédé de séparation de mercure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4729882A (en) * 1985-03-28 1988-03-08 Tokyo Metropolitan Environmental Service Corporation Process for cleaning mercury-containing gaseous emissions
DE4422661A1 (de) * 1994-06-28 1996-01-04 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Verfahren und Anordnung zur kontinuierlichen Abtrennung von Quecksilber aus strömenden Gasen
US6447740B1 (en) * 1998-05-08 2002-09-10 Isca Management Ltd. Mercury removal from flue gas
DE10233173A1 (de) * 2002-07-22 2004-02-12 Bayer Ag Verfahren zur Abscheidung von Quecksilber aus Rauchgasen
US20070053827A1 (en) * 2003-08-12 2007-03-08 Outokumpu Technology Oy Method for the removal of mercury from sulphuric acid with thiosulphate precipitation
WO2009092575A1 (fr) * 2008-01-23 2009-07-30 Vosteen Consulting Gmbh Procédé de séparation de mercure

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