Speciation of Mercury Contaminant in Public Gold Mine Tailing and its Stabilization Using Sulfur and Sulfide

Mercury containing tailing waste from public gold mines in Indonesia is generally deposited on soil without treatment. This research aimed to determine the amount and composition of mercury species in the tailing, and to test the effect of sulfur and sulfide to mercury stabilization. Samples were collected from a tailing pile at different depths in a public gold mine in Kulon Progo, Indonesia. The samples were characterized according to mercury concentrations and Toxicity Characteristic Leaching Procedure (TCLP test). Mercury speciation was carried out using nitrogen gas flow into tailing samples, which were placed in three test tubes. The released mercuric species was entrapped in KCl and KMnO4 solutions. Mercury stabilization was done using sulfur and sodium sulfide. TCLP test was performed to the stabilization products. Mercury concentrations were measured using a mercury analyzer. The results showed that mercury in the tailings were dominated by elemental Hgo, of which concentrations in the tailing piles of 30, 60, and 90 cm depths were 74.7%, 71.6%, and 76.5% respectively. Those of ionic Hg2+ form were 25.3%, 28.4%, and 23.5%, respectively. Additions of sulfur powder and sodium sulfide solution produced stable black-colored mercury sulfide. When compared to sulfide, sulfur was more recommended for stabilizing mercury in the tailing waste. Keywords: mercury; gold mine, speciation, sulfide, sulfur, tailin