CHEMICAL CHARACTERISATION OF ACID MINE DRAINAGE FROM AN ABANDONED GOLD MINE SITE

Acid mine drainage (AMD) is a well-known environmental problem arising from both working and abandoned mines. This process happens when minerals, especially sulphide minerals, are exposed to the environment's atmospheric or water oxidation. The oxidation causes sulphide ions to oxidize to sulphate ions whereby their generation causes water pH decrease and therefore the releasing of toxic metals is increased from a mine site. AMD can cause high concentrations of metals and other pollutants in water. The most common sulphide mineral used during the mining of valuable metals such as Cu, Pb, Zn or Au is pyrite - FeS2. The gold bearing form of this mineral was used during mining activities at the biggest gold deposit in Bosnia and Herzegovina in the Bakovici mine. The chemical parameters that were selected for research and for determining of the AMD process in water were: pH, electrical conductivity, oxidation-reduction potential, concentrations of sulphates, and the amounts of Fe, Na, Si, Al, Cr, Cu, Pb, Au, As, Zn, Cd and Ag. Additionally, standard parameters for water quality were measured for five samples taken from the River Gvozdanka which passes the gold mine site, one sample of drinkable water - underground source, and three water samples that flowed directly from the mining body. The results showed that the River Gvozdanka and water source of drinkable water were uncontaminated by AMD products but water from the mining body was highly contaminated, especially by sulphates, iron and aluminum. Interestingly gold was still present within the concentration range from 0.5 to 1.0 mu g L-1.