Abstract
The Smolnik deposit is one of the historically best-known and richest Cu-Fe ore deposits in the Slovak Republic. The discharging mine waters of pH 3.7-4.1 containing high concentrations of sulphates, Fe, Mn, Cu, Zn and Al have a negative effect, mainly on the Smolnik creek.
The paper deals with the study of metal distribution between water and sediment in the Smolnik creek depending on pH and the metal concentrations. The results of metal concentration decrease in surface water and increase of metal concentration in sediment were compared with the results of our experimental study focused on pH influence on iron, copper, aluminium, zinc and manganese precipitation from raw AMD from mine Smolnik. There was determined that aluminium is precipitated (98.5 %) in the pH range from 4 to 5.5. Precipitation of copper was carried out in accordance with the literature, where copper begins to precipitate at pH > 4 and total precipitation occurs at pH 6 with the efficiency 92.3 %. In spite of iron occurrence in AMD mainly as Fe2+, which precipitates at pH < 8.5, the experimental results confirmed the iron precipitation across studied pH range (4-8) by the progressive oxidation of Fe2+ to Fe3+ by oxygen from air and its precipitation in the form of Fe(OH)3, which starts at pH 3.5. Zinc is precipitated in the range of pH 5.5 to 7 and 84 % of total Zn was precipitated in this interval.
It was confirmed that increasing of pH of AMD due to its dissolution by surface water induces precipitation of metals and their accumulation in sediment in the determined intervals of pH.
