Mercury is an important but poorly understood pollutant. It is naturally present in the environment in soil and plants and enters the atmosphere as a result of evaporation, volcanic eruptions and forest fires. However, one of the main sources of mercury pollution is evaporation from industrial and municipal waste .
HgS (s) is relatively insoluble and less volatile than other forms of mercury, and therefore potentially less harmful . Cinnabar (hexagonal, red, a-HgS (s)) is stable in waste due to slow oxidation kinetics, hence mercury poses a higher long term potential risk.
Pyrite is the most common metal sulfide in nature; it is a widely available and inexpensive material that, as a result of experimental results obtained, interacts well with mercury.
The studies of the immobilization of mercury in waste with sulfur and pyrite show that pyrite contributes to a more complete stabilization of mercury, in comparison with sulfur, and after 90 minutes of reaction in a ball mill (for example, mshl-1), significantly better results are achieved with less consumption of raw materials.
Moreover, the difference between the amount of mobile mercury generated by using sulfur and using pyrite was comparable to the difference between the Hg (II) and mobile mercury content, obtained by assessing the possibility of mercury input from immobilized waste.
Also, a series of experiments on stabilization with a mixture of sulfur and pyrite were carried out at various ratios of sulfur and pyrite. As a result, it was found that significant immobilization (more than 99%) in 90 minutes can be achieved using a mixture of sulfur and pyrite in a 1: 1 ratio. The amount of the mixture was taken in relation to mercury in the ratio Hg: (FeS2 + S8) = 1: 3.
As a result, it was determined that it is advisable to use mercury with pyrite for the immobilization of mercury from mercury-containing waste (the optimal ratio of the mixture components is 1: 1), the efficiency of mercury stabilization can be more than 99%.
The reported study was funded by RFBR according to the research project № 18-29-24212.
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|Affiliation of speaker||D. Mendeleev University of Chemical Technology of Russia|
|Position of speaker||Doctor of Technical Sciences|
|Publication||International journal «Resource-Efficient Technologies»|