How Much Of Thallium Pollutants Will Be Released To Environment By Utilizing Minerals?
A recent research has explored the environmental exposure and flux of thallium to the environment; and it provides the foundations for theoretical calculation to control Tl pollution by utilizing of Tl-rich pyrite minerals.
This paper, “Environmental Exposure and Flux of Thallium by Industrial Activities Utilizing Thallium-Bearing Pyrite”, written by professor CHEN Yong-Heng et al. from Key Laboratory of Waters Safety & Protection in the Pearl River Delta, Ministry of Education, Guangzhou University, is published in Science China: Earth Sciences (No.9, 2013) .
Thallium is a rare but widely dispersed element with high toxicity .Severe thallium intoxication could lead to neurological disease and death. Thallium has low background levels in environment, with concentrations of about 0.01~0.05 μg/L in freshwater and marine respectively. It usually presents in some specific sulfide and silicate minerals. Due to the mining activities of Tl-rich sulfide minerals, Tl pollution is increasingly severe in China; and the Tl level in some industrial waste water even exceeded 10 mg/L.
This paper firstly combined the sequential extraction and ICP-MS to investigate the geo-chemical speciation and partitioning transformation of thallium during the production process, analyzed the environmental exposure, assessed accurately of its environmental flux.
Result showed that 40% of Tl in the pyrite minerals was active, among which 25% of Tl was washed into water during gas cleaning process, and 15% of the active Tl retained in the slags that could be possibly transferred to the soil or water with the slag deposal or being reused during roasting of ores. Meanwhile, the other portion (60% of Tl) remained relatively stable in the residual phase. Given the above information, with an industrial site bearing ore (20 mg Tl/kg) production of three million tons annually, 24 tons of Tl would enter into the environment, including 15 tons into the aquatic system, which brings serious Tl pollution into the environment. Therefore, it is urgent to control Tl pollution from the headstream.
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