Geochemical and mineralogical characteristics of some gold mine tailings in the Eastern Desert of Egypt

The adverse environmental effects of mine tailings disposal on the surrounding ecosystems are worldwide environmental problems. Due to environmental issues related to tailings discharged on land surface, detailed tailings characterization is a prerequisite for a long-term management solution. The tailings from four gold mines in Egypt, namely Fatira, El Sid, Barramiya, and Atud were investigated for their geochemical-mineralogical features and the effect of weathering behavior on the release of their heavy elements. The tailings samples were investigated by mineralogical (XRD and ESEM-EDS), physical (grain-size distribution) and geochemical (XRF) techniques. Most of the tailings have uniform silt-size with fine to very finesand and clay. Atud tailings have coarse to fine sands. High carbonate, predominantly calcite was found for the samples from Fatira and Atud, calcite-ankerite from El Sid and dolomite from Barramiya with little sulfide-content. High-mean of Cr (569287 mg/kg), Ni (89191 mg/kg) and Co (4221 mg/kg) values are coinciding with the ultramafic nature in Atud and Barramiya tailings. El Sid tailings have a high-mean concentration of Zn (1357 mg/kg) and Pb (1349 mg/kg). Barramiya tailings have a high-mean As concentration (2635 mg/kg). The Fatira tailings are characterized by high-mean values of Sr (444 mg/kg) and Cu (280 mg/kg) arising from auriferous mineralization. High Sr concentrations in Fatira tailings are mainly due to its adsorption to iron oxides. Pyrite oxidation is conceded along the cracks and/or the edges of the crystals in the El Sid, Barramiya and Atud tailings. The Threshold Effect Level (TEL) values indicated high contamination from heavy elements to the neighboring ecosystem. The tailings were deposited downstream into the small wadis. Wind and water erosion can dissolve efflorescent materials enriched in toxic elements like As, Zn, and Pb at tailings surface. The release of contaminants could be catastrophic for the environment without mine site rehabilitation strategies.