Sustained disposal of superfluous liquid mercury
Metallic mercury and mercury compounds will fall under the EU-wide Export Ban as of 15th March 2011. In addition, liquid mercury from defined industrial applications or production processes (e.g. from the chlorine industry or the cleaning of natural gas) will be classified as waste as of 15th March 2011 and, according to the Guideline, must be disposed of in a manner which does not pose a threat to health or to the environment.
Experts recommend: Stabilisation before disposal
In light of the Mercury Guideline, options for the environmentally compatible final storage of mercury that is no longer needed are being examined and discussed at the EU level. The company DELA GmbH has come up with a stabilisation procedure with which metallic mercury can be converted into a substance that is safe for the environment. According to the current state of the art, the transformation of liquid mercury into non-toxic mercury sulphide is the safest disposal solution in the long run.
Transformation to non-toxic mercury sulphide
The process principle of our stabilisation procedure is the reaction of mercury and sulphur in a closed temperature-controlled vacuum mixer in which the chemical compound mercury sulphide (HgS) is produced. Mercury sulphide is a mercury salt with the chemical formula HgS. The red modification of mercury sulphide is also commonly known as cinnabar and is found naturally as a red pigmented mineral.
As the most stable mercury compound, mercury sulphide is hardly water-soluble (10-54 [mol²/l²]) and is therefore classified as non-hazardous to water and non-toxic. Our final product satisfies the currently valid criteria for storage above ground.
An overview of the DELA stabilisation procedure:
- Patented procedure to stabilise metallic mercury
- Transformation to mercury sulphide (HgS): Mercury, sulphur and additives react in a vacuum mixer under vacuum (approx. 0.05 bar absolute)
- Final products: HgS powder or optionally HgS pellets
- Tested quality: Analysis of the final product by two external chemical institutes with regard to the crystallinity, thermal properties and eluate behaviour.
- Final disposal: According to the currently valid eluate criteria, the final HgS product can be stored at suitable depots under defined conditions. The final disposal of mercury sulphide in underground storage facilities, in particular salt mines, is currently the preferred solution
Download – Successful ZIM example: ZIM-Solo-008:
“Safe disposal of liquid mercury by its transformation into non-toxic mercury sulfide”