Gold mining tailing: Environmental availability of metals and human health risk assessment

Abstract

The gold ore from sulfide minerals is, in general, ore dressed by means of nine stages among which stand out flotation and cyanidation. The residues of these steps, containing potentially toxic elements, such as As, Cd, Cr, Mn, Zn and Pb disposed of tailings dams, which might be a source of environmental contamination if not suitably disposed and/or in cases of accidents and overflows. Sequential extraction schemes (SES) have been used to estimate the potential environmental availability of contaminants from environmental matrices and, lately, from residues. This research evaluates the environmental availability of As, Cr, Cd, Mn, Pb, and Zn, by using two different SES, Tessier and Marin (BCR) in cyanidation residues. The analytes were quantified by inductively coupled plasma with optical emission spectrometry (ICP OES). A human health risk assessment was performed considering a scenario of soil contamination by the tailing after failure dam, based on the potential environment availability of metals, resulted from distinct SES studied. The results showed that Mn and Pb are the most labile, and therefore the most dangerous and bioavailable for the surrounding environment (≥75%). Moreover, the scenario simulated demonstrated the risk for human health mostly due to As, Cd and Zn.

Keywords: Dam failure; Gold; Mining tailing; Risk assessment; Sequential extraction schemes.