硫化鉄を用いた低温加熱処理による水銀汚染土壌の浄化技術に関する基礎研究

抄録

An increasing proportion of Environmental pollution with mercury take place in a number of developing countries, in particular, tropical region of South America, Africa and Southeast Asia have experienced tremendous increase in uncontrolled sector gold mining activities using mercury amalgamation technique since late 1970s. In order to resolve the these problems, techniques for the remediation of mercury polluted sites has been demanded in these countries.
In our precious reports, we have studied a remediation technology for mercury contaminated soil/sediment by the low temperature thermal treatment with iron chloride (FeCl₂) as additive. This process is characterized by soil heating method using physico-chemical reaction. However, in this reaction system, toxic hydrogen chloride gas are produced during the heating treatment which might corrode an apparatus and released mercury by heating treatment cannot be recovered as metallic mercury because the mercury reacts with hydrogen chloride gas to produce mercury chloride.
In order to overcome these drawbacks, we have undertaken basic research to develop more suitable remediation technology with another additive. As a results, it was found that mercuric sulfide in soils/sediments was removed more effectively by heating treatment with iron sulfide (FeS) as compared with iron chloride. Released mercury by heating treatment was recovered in the potassium permanganate solution. Moreover, this additive (FeS) is applied not only mercuric sulfide, but also other mercury compounds.
Our preliminary experiments with 2,000mg-Hg · kg^-1 dry weight artificially contaminated soil with mercuric sulfide and heating temperature 300°C showed that around 99% mercury was removed.