Biocycling of Fe in acidic and oxidized mine tailings

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:210505

Fortin, D; Davis, B; Beveridge, T J ^[1]

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1. Univ. of Guelph, Ontario (Canada)

Experiments performed to investigate iron cycling in mine tailings areas at the Kam Kotia Mine in Canada are discussed in this paper. A sequential chemical extraction separated the tailings into iron reactive, iron silicate, and iron pyrite fractions. Bacterial enumeration for sulfate-reducing bacteria and thiobacilli was performed by the most probable number technique. Fresh tailings and bacterial cultures were embedded, sectioned, and studied with transmission/scanning electron microscopy and energy dispersive spectroscopy. Under the highly oxic and acidic conditions near the surface, microbial and chemical oxidation of iron(II) sulfides led to the release of soluble iron in the tailings, with a portion being precipitated as iron (III) oxides on bacterial surfaces. In the lower part of the profile, where slightly oxic and acidic conditions prevailed, the decrease of sulfate and iron concentrations was accompanied by a pH increase and correlated to the presence of sulfate-reducing bacteria, suggesting the formation of iron sulfides within the tailings. Since iron cycling in the tailings depends on both the chemical conditions and the presence of bacteria, it is difficult to model the fate of iron based on chemical parameters only.

• OSTI ID: 210505
• Report Number(s): CONF-9509139--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ACID MINE DRAINAGE
BIOCHEMICAL REACTION KINETICS
IRON
MICROBIAL LEACHING
MINERAL CYCLING
SULFATE-REDUCING BACTERIA
TAILINGS
THIOBACILLUS FERROXIDANS