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Quecksilber in Umwelt und Produkten

Das Quecksilber in Lampen macht in der EU gerade einmal 3 Prozent aller Anwendungen aus. Die größten Mengen an Quecksilber kommen in der Chlor-Alkali-Industrie und als Zahnamalgam zum Einsatz. Die Lampen stellen auch keine bedeutende Quelle für Emissionen in die Umwelt dar. In die Umwelt gelangt das Metall vielmehr durch Bergbau und bei der Energiegewinnung aus Kohle und Öl. Veröffentlicht in Hintergrundpapier.

Behaviour of mercury and mercury compounds at the underground disposal in salt formations and their potential mobilisation by saline solutions

Within the next 40 years, in the European Union approximately 11,000 t of metallic mercury has to be disposed that is no longer used in the chlor-alkali industry or is gained from non-ferrous metal production or the cleaning of natural gas. One disposal option is permanent storage in underground storage sites in salt rock. As a liquid, metallic mercury has been ex-cluded from this disposal option so far. Prior to a permit, it is necessary to investigate the par¬ticular challenges for the disposal practice that originate from the specific properties of me¬tallic mercury (liquid state, formation of toxic gases, laborious clean-up of contaminated areas). On the base of present knowledge a safe permanent storage of metallic mercury in under-ground storage sites is principally feasible. Veröffentlicht in Texte | 07/2014.

Verhalten von Quecksilber und Quecksilberverbindungen bei der untertägigen Ablagerung in Salzformationen, insbesondere ihrer möglichen Mobilisierung durch salinare Lösungen

In den kommenden 40 Jahren sind in der Europäischen Union etwa 11 000 t metallisches Quecksilber zu beseitigen, das in der Chlor-Alkali-Industrie nicht mehr genutzt wird oder bei der Nichteisenmetallproduktion sowie der Gasreinigung anfällt. Eine Option zur Beseitigung ist die dauerhafte Ablagerung in Untertagedeponien (UTD) im Salzgestein. Bislang war metallisches Quecksilber als Flüssigkeit von einer Ablagerung in UTD ausgeschlossen. Auf Basis des heutigen Kenntnisstandes ist eine sichere Dauerlagerung von metallischem Quecksilber in Untertagedeponien im Salzgestein grundsätzlich machbar. Veröffentlicht in Texte | 06/2014.

Markt für Chlor, gasförmig

technologyComment of chlor-alkali electrolysis, diaphragm cell (RER): In the diaphragm process, all reactions take place in only one cell. A diaphragm is used to separate the feed brine (anolyte) and the chlorine formed at the anode from the sodium hydroxide containing solution (catholyte) and the hydrogen formed at the cathode. Without the diaphragm being present during electrolysis, chlorine and hydrogen would form an explosive mixture and sodium hydroxide and chlorine would react to form sodium hypochlorite (NaOCl). Diaphragms used to be made from asbestos but up-todate technology allows for asbestos-free polymer-based diaphragms. Purified brine is fed to the anode compartment and percolates through the diaphragm into the cathode compartment. The percolation rate is controlled by a difference in liquid level between both compartments. At the anodes (metal oxide coated titanium), chlorine gas is formed which is collected and directed to further processing. Cathodes, where water decomposition takes place, are made of activated carbon steel. Catholyte leaving the cell, also called cell liquor, is a mixture of 10-12 wt.-% sodium hydroxide and 15-17 wt.-% sodium chloride in water. This solution is usually evaporated to 50 wt.-% NaOH. In this process, simultaneously most of the salt is removed by precipitation to a final residual of 1 wt.-%. The resulting salt is typically recirculated to brine preparation. The advantage of diaphragm cells is that the quality requirements for the brine and the electrical energy consumption are low. Disadvantageous are the high amount of thermal energy necessary for sodium hydroxide concentration and the comparably low quality of the produced sodium hydroxide and chlorine. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process). technologyComment of chlor-alkali electrolysis, membrane cell (RER): In the membrane cell process, the anode and cathode compartments are separated by a perfluoropolymer cation-exchange membrane that selectively transmits sodium ions but suppresses the migration of hydroxyl ions (OH-) from the catholyte into the anolyte. Saturated brine flows through the anode compartment, where chlorine gas is produced at the anode. The electric field in the electrolysis cell causes hydrated sodium ions to migrate through the membrane into the cathode compartment. The cathode compartment is fed with diluted sodium hydroxide solution. Water is electrolysed at the cathode releasing gaseous hydrogen and hydroxyl ions, which combine with the sodium ions and thus increase the concentration of sodium hydroxide in the catholyte. Typically, the outlet concentration of sodium hydroxide is around 32 wt.-%. A part of the product stream is diluted with demineralised water to about 30 wt.-% and used as catholyte inlet. In some units, a more diluted 23 wt.-% NaOH solution is produced. In these cases, the inlet concentration is adjusted to 20-21 wt.-%. Usually the NaOH solution is evaporated to the marketable concentration of 50 wt.-% using steam. Depleted brine leaving the anode compartment is saturated with chlorine and is therefore sent to a dechlorination unit to recover the dissolved chlorine before it is resaturated with salt for recirculation. The advantages of the membrane cell technique are the very high purity of the sodium hydroxide solution produced and the comparably low energy demand. Disadvantages comprise the high requirements on brine purity, the need for sodium hydroxide evaporation to increase concentration, and the comparably high oxygen content in the produced chlorine. In general, multiple cell elements are combined into a single unit, called electrolyser, of whom the design can be either monopolar or bipolar. In a monopolar electrolyser, the anodes and cathodes of the cells are connected electrically in parallel, whereas in the bipolar design, they are connected in series. Therefore, monopolar electrolysers require high current and low voltage, whereas bipolar electrolysers require low current and high voltage. Since bipolar systems allow higher current densities inside the cells, investment and operating costs are usually lower than for monopolar systems. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process). technologyComment of chlor-alkali electrolysis, mercury cell (RER): The mercury cell process comprises an electrolysis cell and a decomposer. Purified and saturated brine (25-28 wt.-% NaCl in water) is fed to the electrolysis cell on top of a film of mercury (Hg) flowing down the inclined base of the cell. The base of the cell is connected to the negative pole of a direct current supply forming the cathode of the cell. Anodes consisting of titanium coated with oxides of ruthenium and titanium are placed in the brine without touching the mercury film. At the anodes, chlorine gas is formed which is collected and directed to further processing. Due to a high overpotential of hydrogen at the mercury electrode, no gaseous hydrogen is formed; instead, sodium is produced and dissolved in the mercury as an amalgam (mercury alloy). The liquid amalgam is removed from the electrolytic cell and fed to a decomposer, where it reacts with demineralised water in the presence of a graphite-based catalyst to form sodium hydroxide solution and hydrogen. The sodium-free mercury is recirculated back into the cell. Cooling of hydrogen is essential to remove any water and mercury. The sodium hydroxide solution is very pure, almost free from chloride contamination and has usually a concentration of 50 %. Further treatment comprises cooling and removal of catalyst and mercury traces by centrifuges or filters. Advantages of the mercury cell process are the high quality of chlorine and the high concentration and purity of sodium hydroxide solution produced. The consumption of electric energy for electrolysis is, however, higher than for the other techniques and a high purity of the feed brine is required. Inherently, the use of mercury gives rise to environmental releases of mercury. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process). technologyComment of potassium hydroxide production (RER): Potassium hydroxide is manufactured by the electrolysis of potassium chloride brine in electrolytical cells. Hydrogen and chlorine are withdrawn from the cell. The rest of the reaction mixture contains KOH, water, and unreacted potassium chloride. This reaction mixture is then concentrated in an evaporator. Most of the potassium chloride crystallizes by evaporation, and is recycled. After evaporation, the potassium hydroxide is precipitated. Potassium hydroxide, chlorine and hydrogen are obtained from potassium chloride brine according to the following reaction: 2 KCl + 2 H2O -> 2 KOH + Cl2 + H2 Reference: Jungbluth, N., Chudacoff, M., Dauriat, A., Dinkel, F., Doka, G., Faist Emmenegger, M., Gnansounou, E., Kljun, N., Schleiss, K., Spielmann, M., Stettler, C., Sutter, J. 2007: Life Cycle Inventories of Bioenergy. ecoinvent report No. 17, Swiss Centre for Life Cycle Inventories, Dübendorf, CH. technologyComment of sodium chloride electrolysis (RER): Sodium chloride electrolysis

Markt für Natriumchlorid, Pulver

technologyComment of rare earth oxides production, from rare earth oxide concentrate, 70% REO (CN-SC): This dataset refers to the separation (hydrochloric acid leaching) and refining (metallothermic reduction) process used in order to produce high-purity rare earth oxides (REO) from REO concentrate, 70% beneficiated. ''The concentrate is calcined at temperatures up to 600ºC to oxidize carbonaceous material. Then HCl leaching, alkaline treatment, and second HCl leaching is performed to produce a relatively pure rare earth chloride (95% REO). Hydrochloric acid leaching in Sichuan is capable of separating and recovering the majority of cerium oxide (CeO) in a short process. For this dataset, the entire quantity of Ce (50% cerium dioxide [CeO2]/REO) is assumed to be produced here as CeO2 with a grade of 98% REO. Foreground carbon dioxide CO2 emissions were calculated from chemical reactions of calcining beneficiated ores. Then metallothermic reduction produces the purest rare earth metals (99.99%) and is most common for heavy rare earths. The metals volatilize, are collected, and then condensed at temperatures of 300 to 400°C (Chinese Ministryof Environmental Protection 2009).'' Source: Lee, J. C. K., & Wen, Z. (2017). Rare Earths from Mines to Metals: Comparing Environmental Impacts from China's Main Production Pathways. Journal of Industrial Ecology, 21(5), 1277-1290. doi:10.1111/jiec.12491 technologyComment of sodium chloride production, powder (RER, RoW): For the production of dry salt, three different types of sodium chloride production methods can be distinguished namely, underground mining of halite deposits, solution mining with mechanical evaporation and solar evaporation. Their respective products are rock salt, evaporated salt and solar salt: - Underground mining: The main characteristic of this technique is the fact that salt is not dissolved during the whole process. Instead underground halite deposits are mined with traditional techniques like undercutting, drilling and blasting or with huge mining machines with cutting heads. In a second step, the salt is crushed and screened to the desired size and then hoisted to the surface. - Solution mining and mechanical evaporation: In this case, water is injected in a salt deposit, usually in about 150 to 500 m depth. The dissolution of the halite or salt deposits forms a cavern filled with brine. This brine is then pumped from the cavern back to the surface and transported to either an evaporation plant for the production of evaporated salt or transported directly to a chemical processing plant, e.g. a chlor-alkali plant. - Solar evaporation: In this case salt is produced with the aid of the sun and wind out of seawater or natural brine in lakes. Within a chain of ponds, water is evaporated by sun until salt crystallizes on the floor of the ponds. Due to their natural process drivers, such plants must be located in areas with only small amounts of rain and high evaporation rates - e.g. in the Mediterranean area where the rate between evaporation and rainfall is 3:1, or in Australia, where even a ratio up to 15:1 can be found. There are some impurities due to the fact that seawater contains not only sodium chloride. That leads to impurities of calcium and magnesium sulfate as well as magnesium chloride. With the aid of clean brine from dissolved fine salt, these impurities are washed out. As a fourth form on the market, the so-called 'salt in brine' may be found, which is especially used for the production of different chemicals. In this case, the solution mining technique without an evaporation step afterwards is used. This dataset represents the production of dry sodium chloride by underground mining (51%) and by solution mining (49%) with modern solution mining technology (thermo compressing technology). References: Althaus H.-J., Chudacoff M., Hischier R., Jungbluth N., Osses M. and Primas A. (2007) Life Cycle Inventories of Chemicals. ecoinvent report No. 8, v2.0. EMPA Dübendorf, Swiss Centre for Life Cycle Inventories, Dübendorf, CH.

Markt für Natriumhydroxid, ohne Wasser, in 50%igem Lösungszustand

technologyComment of chlor-alkali electrolysis, diaphragm cell (RER, RoW): In the diaphragm process, all reactions take place in only one cell. A diaphragm is used to separate the feed brine (anolyte) and the chlorine formed at the anode from the sodium hydroxide containing solution (catholyte) and the hydrogen formed at the cathode. Without the diaphragm being present during electrolysis, chlorine and hydrogen would form an explosive mixture and sodium hydroxide and chlorine would react to form sodium hypochlorite (NaOCl). Diaphragms used to be made from asbestos but up-todate technology allows for asbestos-free polymer-based diaphragms. Purified brine is fed to the anode compartment and percolates through the diaphragm into the cathode compartment. The percolation rate is controlled by a difference in liquid level between both compartments. At the anodes (metal oxide coated titanium), chlorine gas is formed which is collected and directed to further processing. Cathodes, where water decomposition takes place, are made of activated carbon steel. Catholyte leaving the cell, also called cell liquor, is a mixture of 10-12 wt.-% sodium hydroxide and 15-17 wt.-% sodium chloride in water. This solution is usually evaporated to 50 wt.-% NaOH. In this process, simultaneously most of the salt is removed by precipitation to a final residual of 1 wt.-%. The resulting salt is typically recirculated to brine preparation. The advantage of diaphragm cells is that the quality requirements for the brine and the electrical energy consumption are low. Disadvantageous are the high amount of thermal energy necessary for sodium hydroxide concentration and the comparably low quality of the produced sodium hydroxide and chlorine. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process). technologyComment of chlor-alkali electrolysis, membrane cell (CA-QC, RER, RoW): In the membrane cell process, the anode and cathode compartments are separated by a perfluoropolymer cation-exchange membrane that selectively transmits sodium ions but suppresses the migration of hydroxyl ions (OH-) from the catholyte into the anolyte. Saturated brine flows through the anode compartment, where chlorine gas is produced at the anode. The electric field in the electrolysis cell causes hydrated sodium ions to migrate through the membrane into the cathode compartment. The cathode compartment is fed with diluted sodium hydroxide solution. Water is electrolysed at the cathode releasing gaseous hydrogen and hydroxyl ions, which combine with the sodium ions and thus increase the concentration of sodium hydroxide in the catholyte. Typically, the outlet concentration of sodium hydroxide is around 32 wt.-%. A part of the product stream is diluted with demineralised water to about 30 wt.-% and used as catholyte inlet. In some units, a more diluted 23 wt.-% NaOH solution is produced. In these cases, the inlet concentration is adjusted to 20-21 wt.-%. Usually the NaOH solution is evaporated to the marketable concentration of 50 wt.-% using steam. Depleted brine leaving the anode compartment is saturated with chlorine and is therefore sent to a dechlorination unit to recover the dissolved chlorine before it is resaturated with salt for recirculation. The advantages of the membrane cell technique are the very high purity of the sodium hydroxide solution produced and the comparably low energy demand. Disadvantages comprise the high requirements on brine purity, the need for sodium hydroxide evaporation to increase concentration, and the comparably high oxygen content in the produced chlorine. In general, multiple cell elements are combined into a single unit, called electrolyser, of whom the design can be either monopolar or bipolar. In a monopolar electrolyser, the anodes and cathodes of the cells are connected electrically in parallel, whereas in the bipolar design, they are connected in series. Therefore, monopolar electrolysers require high current and low voltage, whereas bipolar electrolysers require low current and high voltage. Since bipolar systems allow higher current densities inside the cells, investment and operating costs are usually lower than for monopolar systems. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process). technologyComment of chlor-alkali electrolysis, mercury cell (RER, RoW): The mercury cell process comprises an electrolysis cell and a decomposer. Purified and saturated brine (25-28 wt.-% NaCl in water) is fed to the electrolysis cell on top of a film of mercury (Hg) flowing down the inclined base of the cell. The base of the cell is connected to the negative pole of a direct current supply forming the cathode of the cell. Anodes consisting of titanium coated with oxides of ruthenium and titanium are placed in the brine without touching the mercury film. At the anodes, chlorine gas is formed which is collected and directed to further processing. Due to a high overpotential of hydrogen at the mercury electrode, no gaseous hydrogen is formed; instead, sodium is produced and dissolved in the mercury as an amalgam (mercury alloy). The liquid amalgam is removed from the electrolytic cell and fed to a decomposer, where it reacts with demineralised water in the presence of a graphite-based catalyst to form sodium hydroxide solution and hydrogen. The sodium-free mercury is recirculated back into the cell. Cooling of hydrogen is essential to remove any water and mercury. The sodium hydroxide solution is very pure, almost free from chloride contamination and has usually a concentration of 50 %. Further treatment comprises cooling and removal of catalyst and mercury traces by centrifuges or filters. Advantages of the mercury cell process are the high quality of chlorine and the high concentration and purity of sodium hydroxide solution produced. The consumption of electric energy for electrolysis is, however, higher than for the other techniques and a high purity of the feed brine is required. Inherently, the use of mercury gives rise to environmental releases of mercury. References: Euro Chlor (2013) An Eco-profile and Environmental Product Declaration of the European Chlor-Alkali Industry, Chlorine (The chlor-alkali process).

Behaviour of mercury and mercury compounds at the underground disposal in salt formations and their potential mobilisation by saline solutions

In den kommenden 40 Jahren sind in der Europäischen Union etwa 11 000 t metallisches Quecksilber zu beseitigen, das in der Chlor-Alkali-Industrie nicht mehr genutzt wird oder bei der Nichteisenmetallproduktion sowie der Gasreinigung anfällt. Eine Option zur Beseitigung ist die dauerhafte Ablagerung in Untertagedeponien (UTD) im Salzgestein. Bislang war metallisches Quecksilber als Flüssigkeit von einer Ablagerung in UTD ausgeschlossen. Vor einer Zulassung ist es notwendig, die besonderen Herausforderungen zu untersuchen, die sich aus den spezifischen Eigenschaften des metallischen Quecksilbers (flüssiger Zustand, Bildung toxischer Gase, aufwendige Reinigung kontaminierter Flächen) für die Entsorgungspraxis ergeben. Auf Basis des heutigen Kenntnisstandes ist eine sichere Dauerlagerung von metallischem Quecksilber in Untertagedeponien im Salzgestein grundsätzlich machbar. Im Normalbetrieb der UTD ist nicht mit einer Beeinträchtigung der Betriebssicherheit zu rechnen. Es sind jedoch zusätzliche technische und organisatorische Maßnahmen zu treffen, um das Risiko einer Freisetzung flüssigen und gasförmigen Quecksilbers im Zuge von Unfällen zu minimieren. Eine Beeinträchtigung der Betriebssicherheit sollte nicht zu besorgen sein. Empfohlene Maßnahmen beinhalten eine für die Betriebsphase störfallsichere Auslegung der Transport- und Lagerbehälter und eine Auslagerung der stofflichen Eingangskontrolle zum Abfallerzeuger. Empfohlen werden zudem eine kampagnenweise Einlagerung von Behältern und der unverzügliche Verschluss von Einlagerungsabschnitten. Nach Verschluss der gesamten Untertagedeponie gehen bei planmäßiger Entwicklung des UTD-Gesamtsystems vom abgelagerten Quecksilber keine spezifischen Umweltrisiken aus. Im hypothetischen Fall eines Lösungszuflusses wirkt die niedrige Löslichkeit reinen metallischen Quecksilbers als innere Barriere. Quelle: Forschungsbericht

Behaviour of mercury and mercury compounds at the underground disposal in salt formations and their potential mobilisation by saline solutions

In den kommenden 40 Jahren sind in der Europäischen Union etwa 11 000 t metallisches Quecksilber zu beseitigen, das in der Chlor-Alkali-Industrie nicht mehr genutzt wird oder bei der Nichteisenmetallproduktion sowie der Gasreinigung anfällt. Eine Option zur Beseitigung ist die dauerhafte Ablagerung in Untertagedeponien (UTD) im Salzgestein. Bislang war metallisches Quecksilber als Flüssigkeit von einer Ablagerung in UTD ausgeschlossen. Vor einer Zulassung ist es notwendig, die besonderen Herausforderungen zu untersuchen, die sich aus den spezifischen Eigenschaften des metallischen Quecksilbers (flüssiger Zustand, Bildung toxischer Gase, aufwendige Reinigung kontaminierter Flächen) für die Entsorgungspraxis ergeben. Auf Basis des heutigen Kenntnisstandes ist eine sichere Dauerlagerung von metallischem Quecksilber in Untertagedeponien im Salzgestein grundsätzlich machbar. Im Normalbetrieb der UTD ist nicht mit einer Beeinträchtigung der Betriebssicherheit zu rechnen. Es sind jedoch zusätzliche technische und organisatorische Maßnahmen zu treffen, um das Risiko einer Freisetzung flüssigen und gasförmigen Quecksilbers im Zuge von Unfällen zu minimieren. Eine Beeinträchtigung der Betriebssicherheit sollte nicht zu besorgen sein. Empfohlene Maßnahmen beinhalten eine für die Betriebsphase störfallsichere Auslegung der Transport- und Lagerbehälter und eine Auslagerung der stofflichen Eingangskontrolle zum Abfallerzeuger. Empfohlen werden zudem eine kampagnenweise Einlagerung von Behältern und der unverzügliche Verschluss von Einlagerungsabschnitten. Nach Verschluss der gesamten Untertagedeponie gehen bei planmäßiger Entwicklung des UTD-Gesamtsystems vom abgelagerten Quecksilber keine spezifischen Umweltrisiken aus. Im hypothetischen Fall eines Lösungszuflusses wirkt die niedrige Löslichkeit reinen metallischen Quecksilbers als innere Barriere. Quelle: Forschungsbericht

Verhalten von Quecksilber und Quecksilberverbindungen bei der untertägigen Ablagerung in Salzformationen, insbesondere ihrer möglichen Mobilisierung durch salinare Lösungen

In den kommenden 40 Jahren sind in der Europäischen Union etwa 11 000 t metallisches Quecksilber zu beseitigen, das in der Chlor-Alkali-Industrie nicht mehr genutzt wird oder bei der Nichteisenmetallproduktion sowie der Gasreinigung anfällt. Eine Option zur Beseitigung ist die dauerhafte Ablagerung in Untertagedeponien (UTD) im Salzgestein. Bislang war metallisches Quecksilber als Flüssigkeit von einer Ablagerung in UTD ausgeschlossen. Vor einer Zulassung ist es notwendig, die besonderen Herausforderungen zu untersuchen, die sich aus den spezifischen Eigenschaften des metallischen Quecksilbers (flüssiger Zustand, Bildung toxischer Gase, aufwendige Reinigung kontaminierter Flächen) für die Entsorgungspraxis ergeben. Auf Basis des heutigen Kenntnisstandes ist eine sichere Dauerlagerung von metallischem Quecksilber in Untertagedeponien im Salzgestein grundsätzlich machbar. Im Normalbetrieb der UTD ist nicht mit einer Beeinträchtigung der Betriebssicherheit zu rechnen. Es sind jedoch zusätzliche technische und organisatorische Maßnahmen zu treffen, um das Risiko einer Freisetzung flüssigen und gasförmigen Quecksilbers im Zuge von Unfällen zu minimieren. Eine Beeinträchtigung der Betriebssicherheit sollte nicht zu besorgen sein. Empfohlene Maßnahmen beinhalten eine für die Betriebsphase störfallsichere Auslegung der Transport- und Lagerbehälter und eine Auslagerung der stofflichen Eingangskontrolle zum Abfallerzeuger. Empfohlen werden zudem eine kampagnenweise Einlagerung von Behältern und der unverzügliche Verschluss von Einlagerungsabschnitten. Nach Verschluss der gesamten Untertagedeponie gehen bei planmäßiger Entwicklung des UTD-Gesamtsystems vom abgelagerten Quecksilber keine spezifischen Umweltrisiken aus. Im hypothetischen Fall eines Lösungszuflusses wirkt die niedrige Löslichkeit reinen metallischen Quecksilbers als innere Barriere. Quelle: Forschungsbericht

Verhalten von Quecksilber und Quecksilberverbindungen bei der untertägigen Ablagerung in Salzformationen, insbesondere ihrer möglichen Mobilisierung durch salinare Lösungen

In den kommenden 40 Jahren sind in der Europäischen Union etwa 11 000 t metallisches Quecksilber zu beseitigen, das in der Chlor-Alkali-Industrie nicht mehr genutzt wird oder bei der Nichteisenmetallproduktion sowie der Gasreinigung anfällt. Eine Option zur Beseitigung ist die dauerhafte Ablagerung in Untertagedeponien (UTD) im Salzgestein. Bislang war metallisches Quecksilber als Flüssigkeit von einer Ablagerung in UTD ausgeschlossen. Vor einer Zulassung ist es notwendig, die besonderen Herausforderungen zu untersuchen, die sich aus den spezifischen Eigenschaften des metallischen Quecksilbers (flüssiger Zustand, Bildung toxischer Gase, aufwendige Reinigung kontaminierter Flächen) für die Entsorgungspraxis ergeben. Auf Basis des heutigen Kenntnisstandes ist eine sichere Dauerlagerung von metallischem Quecksilber in Untertagedeponien im Salzgestein grundsätzlich machbar. Im Normalbetrieb der UTD ist nicht mit einer Beeinträchtigung der Betriebssicherheit zu rechnen. Es sind jedoch zusätzliche technische und organisatorische Maßnahmen zu treffen, um das Risiko einer Freisetzung flüssigen und gasförmigen Quecksilbers im Zuge von Unfällen zu minimieren. Eine Beeinträchtigung der Betriebssicherheit sollte nicht zu besorgen sein. Empfohlene Maßnahmen beinhalten eine für die Betriebsphase störfallsichere Auslegung der Transport- und Lagerbehälter und eine Auslagerung der stofflichen Eingangskontrolle zum Abfallerzeuger. Empfohlen werden zudem eine kampagnenweise Einlagerung von Behältern und der unverzügliche Verschluss von Einlagerungsabschnitten. Nach Verschluss der gesamten Untertagedeponie gehen bei planmäßiger Entwicklung des UTD-Gesamtsystems vom abgelagerten Quecksilber keine spezifischen Umweltrisiken aus. Im hypothetischen Fall eines Lösungszuflusses wirkt die niedrige Löslichkeit reinen metallischen Quecksilbers als innere Barriere. Quelle: Forschungsbericht

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