A MINERALOGICAL AND GEOCHEMICAL ASSESSMENT OF THE TAILING IMPOUNDMENT AT RUDNANY DEPOSIT, SLOVAKIA

Mineralogical composition of mining wastes deposited in voluminous tailing impoundments around the world is the key factor that controls retention and release of pollutants. Here we report geochemical and mineralogical investigation of one tailing impoundment from Slovakia. Ore deposit Rudnany was exploited from the end of 19th century and at 1963 the ore started to be extracted by flotation process (barite, siderite and sulfides). Waste after flotation was deposited into one tailing impoundment, which carries approximately 9.9 million tones of material. On average the tailing contains 17.39% of BaSO4, 20.32% of Fe and 0.057% of Cu. Also significant are contents of Sb and Hg (Jancura et al., 2005). The most common mineral in heavy fraction is barite; siderite is also frequent and is slowly replaced by secondary Fe oxides in the oxidation part of tailing. Most common sulfides are minerals from tetrahedrite group and pyrite, less common is chalcopyrite, bornite and cinnabar are rare. In oxidation zone of tailing all sulfides except tetrahedrite are being replaced by secondary oxides of variable composition. Also common are grains of Cu and Fe oxides. The grains may be a product of a complete replacement of the ores or they may have precipitated from the solutions which circulate through the impoundments.