Scholarly record

ACID GENERATION AND METAL LEACHING POTENTIAL OF SULFIDE-BEARING ROCKS IN THE VERHNE-KRICHALSKAYA AREA (WESTERN CHUKOTKA, RUSSIA)

Tatyana Lubkova

Abstract

The natural oxidation of iron-sulfide minerals (mainly pyrite) contained in mine waste material can produce the acid rock drainage (ARD). It leads to low acidity, high sulfate and iron concentration in surface and ground water and its heavy-metal contamination. This study investigates ARD prediction for sulfide-bearing mine waste rocks in the Verhne-Krichalskaya area, where the epithermal gold-silver deposit is located (Western Chukotka, Russia). Twenty samples of waste rocks (altered dacites, andesites and rubblerocks) were collected by drilling during exploration and analyzed to estimate their risk of acidic and contaminated drainage. Geochemical tests included acid-base accounting tests, total-metal contents tests and multiple water leach tests. Trace elements were obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES). Multiple water leachates were analyzed using potentiomentry, conductivity measurement, titration analysis, and inductively coupled plasma mass spectrometry (ICP-MS) to analyze contents of dissolved toxic elements. According the results, altered dacites and rubblerocks generally must be considered as potentially or possible acid generating (PAG or Uncertain) compared to altered andesites which are mainly non-acid generating (Non-AG). Concentrations of some toxic elements (primarily, Al, As, Sb, Mo) in leachates are much above the Environmental design limits (EDLs) used for fishery water quality assessment.

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