Environmental Impact Variability of Copper Tailing Dumps in Fushe Arrez (Northern Albania): The Role of Pyrite Separation during Flotation

Abstract

Acid mine drainage and potentially toxic elements release are a major source of pollution in sulfide-rich mining sites. Pyrite is the most impacting mineral due to its high acidification potential when it reacts with water under oxidizing conditions. At the Fushe Arrez dressing plant in Northern Albania, a volcanic massive sulfide copper mining district, pyrite was in past separated, with a double flotation process, to produce a pyrite concentrate and relatively-pyrite-poor tailings. In the last twenty years single flotation has replaced the double flotation process and pyrite has been deposited in pyrite-rich tailings stacked separately from the old ones. The study of the solid tailing materials and natural waters flowing through the dumping area, together with leaching tests show that waters interacting with single flotation tailings are slightly more acidic and much higher in total metal contents than those interacting with double flotation tailings. Also, the metal distribution is different, with the former being higher in sulfide-hosted metals and the latter higher in gangue-hosted metals. It is thus suggested that separation of pyrite can play an important role in the sustainable mining of pyrite-rich ores, either for dumping high hazardous pyrite concentrate separately or for marketing it as a by-product. An implementation of studies for the industrial uses of pyrite is pivotal in this last case.

Buffering Copper Tailings Acid Mine Drainage: Modeling and Testing at Fushë Arrëz Flotation Plant, Albania

“…We here investigated the same tailing dumps collected and partially studied by Grieco et al [16] at the Fushë Arrëz dressing plant. As reported by Grieco et al [16], samples were assembled to be the most representative possible of each dump material. The two dumps cover an area of approximately 6 × 10 4 m 2 (FA4) and 18 × 10 4 m 2 (FA3), respectively.…”

“…After leaching and buffering tests, the solutions were analyzed with two different techniques to evaluate the concentration of the same ions selected by Grieco et al [16]. Sulfur percentage values were assumed based on the same study.…”

“…According to Grieco et al [16] the cations present in high concentration and that require modeling are: Fe 2+ , Fe 3+ , Al 3+ , Cu 2+ , Ca 2+ . Anions deriving from water equilibrium, dissolution of sulfides and carbonates and are: SO 2− 4 , HSO − 4 , CO 2− 3 , HCO − 3 , OH − .…”

“…As the leaching waters contain other soluble ionic species besides those appearing in Equation ( 6) [16], these have to be considered as well. The major ions selected for the implemented model according to their concentration in leaching waters are: Fe 2+ Fe 3+ Al 3+ Cu 2+ Ca 2+ .…”

“…In addition to several other factors affecting AMD, the specific enrichment procedure can play a major role in the potential acidity of dumped tailings. Previous studies show that a different combination of flotation processes results in tailings with quite different environmental impact [16,17] and with high but still variable acidification capacity as a response to leaching tests [16].…”