Liquid mercury as cathode (negative pole) in one of the three chlorine production technologies
The phasing out of mercury technology in the Chlor-Alkali industry
In 2001, the European chlor-alkali sector voluntarily committed to a phase-out of mercury cell technology by 2020. Meanwhile, however, under the Industrial Emissions Directive, the BAT conclusions (Best Available Techniques) have become legally binding. The national authorities had to ‘reconsider permit conditions’ and ‘take into account the BAT conclusions', implying that four years after publication of these BAT conclusions, this means before 11 December 2017, mercury-based production technology should be ceased.
Consequently, the European chlor-alkali producers using the mercury technology have done major efforts and investments to convert or dismantle these production plants. Euro Chlor has created a special page within this website that monitors these operations and keeps you up-to-date with the latest available information.
Regulation (EU) 2017/852 on Mercury sets the rules for the safe temporary storage and safe permanent disposal of mercury and mercury compounds. Elemental mercury no longer used in chlor-alkali mercury cells (‘excess mercury’) can be stored temporarily under specific conditions, before being converted into mercury sulphide for permanent disposal (e.g. in salt mines).
The chlor-alkali industry has a long history of safe handling and storage of liquid mercury and the experience is documented in several Guidance Documents in Euro Chlor’s technical library, such as the ‘Guidelines for the safe handling and temporary storage of mercury from chlor-alkali plants in shut-down or conversion’.
Key facts about the European chlor-alkali industry:
- Nearly 10 million tons of chlorine, 11 million tons of caustic soda and 0.3 million tons of hydrogen are produced each year.
- Chlorine and caustic soda are essential to economic and social welfare and are used in a wide variety of products e.g. plastics, medicine, disinfectants, clothing, building materials, etc.
- At the beginning of 2017, the mercury technology accounted for 17.4% of EU production capacity, membrane production was 66%.
- The total amount of mercury still in use in chlor-alkali manufacturing is about 5400 tons (end 2016).
- The chlor-alkali industry has a long history of safe handling and storage of liquid mercury and the experience is documented in several Guidance Documents in Euro Chlor’s technical library..
Ratification of the Minamata Convention on Mercury by the EU
The EU signed the Minamata Convention on Mercury in October 2013 and thereby committed to ensure its ratification and implementation across the Union. The final ratification package was published in May 2017 and consisted of:
- Regulation (EU) 2017/852 on Mercury repealing and replacing Regulation (EC) 1102/2008;
- Council Decision (EU) 2017/939 concerning the conclusion on behalf of the EU of the Minamata Convention on Mercury.
This package amended existing EU legislation by:
- maintaining the substantive provisions that banned mercury exports in the 2008 Mercury Regulation;
- placing additional restrictions on specific uses of mercury;
- prohibiting within the EU any future new uses of mercury in products and industry, unless significant environmental and health benefits are demonstrated and there are no mercury-free alternatives;
- regulating the temporary storage and permanent disposal of mercury waste;
- bringing certain additional adjustments to current EU law, necessary to allow the EU to ratify the Convention.
Those who are interested in the drafting of the package can find more information on the official the Commission mercury web pages.
Contact: Marleen Pauwels, mpa[at]cefic.be, tel. +32 2 676 72 47
Safe temporary storage and safe permanent disposal of mercury and mercury compounds
The safety of long-term mercury storage is regulated by existing EU waste legislation (Directives 2008/98/EC & 1999/31/EC and Decision 2003/33/EC) which ensures only storage sites with the necessary permits for the storage of hazardous waste can be used. In the case of liquid mercury, the permit shall also include requirements for regular visual inspections of the containers and the installation of appropriate vapour detection equipment to detect any leak.
Storage of liquid (metallic) mercury in sealed containers in deep salt mines was originally considered a very safe option for the disposal by hazardous waste experts and established storage company operators. This solution reduces the risk of accidental environmental exposure as the mercury does not need to be moved after it has been stored in a dedicated area (Read here the Euro Chlor March 2016 full position paper).
The 2017 Mercury Regulation, however, only allows such storage on a temporary basis, for a maximum period of 5 years, with the possibility to extend it with 3 additional years through a delegated act. After that period, all liquid mercury should be converted into ‘mercury sulphide or a comparable chemical compound which is equally or more stable and equally or less soluble in water and that presents no greater environmental or health hazard than mercury sulfide’. The mercury sulphide or comparable chemical compound can then be permanently disposed of, respecting the general European hazardous waste rules and some additional provisions specified in the Mercury Regulation. E.g. mercury sulphide can be permanently stored in underground salt mines or hard rock formations; or in solidified form also in above-ground storages.
Available stabilisation technology options
At this moment, there are four companies active in the conversion of mercury to mercury-sulphide. More information about the options is presented below. Information is taken from materials provided by the companies and should not be read as an endorsement of any one particular option and no ranking is implied.
BATREC in Wimmis, Switzerland
BATREC is under the management of SARP Industries within the Veolia Group
The installation consists of two parallel reactors and a filter-press and has a capacity of approx. 1200 tonnes/y. BATREC has two tonne containers available for the transport of the mercury waste from the electrolysis to their plant in Switzerland. For this transportation, special arrangements have to be agreed with the authorities.
The process works in a wet environment resulting in a mercury-sulphide cake with less than 5% water. A conversion rate of 99.999% of the mercury to mercury-sulphide is guaranteed.
The mercury sulphide is packed in plastic bags which then go into 200 liter drums. The mercury sulphide drums are stored in the salt mine of K+S in Herfa Neurode, Germany.
The process has been operational since 2016.
ECON Industries Services
ECON has a mobile unit, which is able to convert a minimum of four tonnes of mercury per day. It is a dry process.
The operators of the electrolysis plant operate the installation on the premises of the electrolysis plant. Process supervision and responsibility is by the econ industries supervisor on-site. The electrolysis plant has to arrange the environmental permit and has to take care of the required utilities and operators.
Two on site projects with an overall amount of > 500 tons have been successfully completed. The mercury sulphide has been transferred to K&S in Germany.
Mayasa is constructing a mercury stabilisation & solidification plant with a capacity of 300 ton mercury per year.
It is expected that the plant will be operational at the end of 2018. Mayasa has a metallic mercury storage capacity of 2,400 ton.
REMONDIS QR in Dorsten, Germany
The installation has a capacity of approx. 800 tonnes/year. The liquid mercury is converted in a dry process to mercury sulphide.The mercury-sulphide is packed in drums and disposed of in the salt mine of K+S in Herfa Neurode, Germany.
The process has been operational since 2014.
Chlor-alkali metallic mercury reporting to the Commission
According to the 2008 Regulation, the quantities of metallic mercury on sites needed to be reported yearly to the Commission and the Competent Authorities. Euro Chlor volunteered to gather the data from the chlor-alkali sites of the Euro Chlor member companies in order to facilitate reporting to the Commission.
The 2017 Mercury Regulation review provides some more details on the reporting and on certificates and record keeping, ensuring traceability.
Euro Chlor yearly provides, on behalf of all member companies utilising mercury cell technology, the following data:
- best estimate of total amount of mercury still in use in the chlor-alkali cells
- total amount of metallic mercury stored in the facility.
Download the Total amount of metallic mercury on site 2017 document (PDF).
The data are publicly available on ec.europa.eu.
Mercury emissions - Individual plant data
In accordance with the Euro Chlor commitment for openness and transparency on progress in the sustainability programme, you will find here the individual plant data for mercury emissions in the European chlor-alkali sector.
Trend of mercury emissions (2017 - PDF)
Euro Chlor video production on responsible handling of mercury
Euro Chlor has produced a video on the handling of mercury in the chlor-alkali industry in a responsible way. While respecting the EU regulation saying to phase-out mercury by the end of 2017, the European chlor-alkali producers are actively engaged in the application of best practices when handling mercury during normal operation and during conversion to other technology. View the Euro Chlor video on responsible mercury handling.