Environmental impact of the historical Cu smelting in the Rudawy Janowickie Mountains (south-western Poland)
Abstrakt
Mining and smelting of Cu ores in the Rudawy Janowickie Mountains (southwestern Poland) from the 14th to the 16th century produced pyrometallurgical slags which currently form unconfined slag heaps in forests or are distributed within soils and streambeds. At present, the slag affected area has approximately 10 km(2).
Chemical and mineralogical analyses of the slags, slag-contaminated and slag-free soils and stream sediments are coupled with leaching experiments and speciation modeling to determine the environmental impact of historical smelting activities. Three subtypes of pyrometallurgical slags occur in the studied area: porous slag and two massive slags (equilibrated slag and undercooled slag) having different phase compositions.
All of the studied slags still contain considerable amounts of metal(loid)s (up to 1.4 wt.% Cu, 1 wt.% Zn, 750 ppm Pb and 300 ppm As). A simple 24-hour laboratory slag-leaching experiment, using three different solutions (distilled water, stream water, citric acid solution), indicate the release of metal(loid)s under simulated natural conditions.
Leachates from a stream water solution and distilled water contain lower concentrations of metal(loid)s (<0.1% of total contaminant concentration in the solid) compared to leachates from a citric acid solution. Furthermore, leaching tests indicate that the release of the metal(loid)s is higher for porous slags than for those having a massive texture.
Chemical analyses of soils, stream sediments and surface water indicate that some elements reach concentrations exceeding environmentally permissible standards (especially in soils: Cu up to 4000 ppm, Zn up to 1500 ppm, As up to 300 ppm, Pb up to 200 ppm).