wAbstract
@A laboratory weathering study using a humidity cell procedure
was conducted on two sulfide-bearing tailing samples from a metallurgical
site in Ontario (Canada). The test was accompanied by microbiological
studies to enumerate the major groups of sulfur-oxidizing bacteria
and determine their potential role at different stages during
the oxidation process. To evaluate the utility of this method,
results were compared with those of previous laboratory and field
studies on the same materials. The mineralogy of the laboratory
samples differs only by the addition of a small amount of hydronium-bearing
natrojarosite [(Na,H3O)Fe3(SO4)2(OH)6]
to one sample. The progress of sulfide oxidation and the rates
of solute release were determined to evaluate the extent of mineral
dissolution. These processes were influenced strongly by the capacity
of the material to generate acidity, which was enhanced by the
presence of hydronium-bearing natrojarosite. Acid-neutralization
processes occurring during the laboratory tests were affected
by reaction kinetics, consistent with field observations. In particular,
the extent of carbonate-mineral dissolution appears to be different
in the laboratory than in the field, where more prolonged rock-water
interaction allowed more complete chemical equilibration. As a
consequence, the capacity of this test procedure to predict weathering
reactions in mine tailings is limited by its inability to reproduce
the weathering sequence observed in the field. The results of
the microbiological study showed that distinct groups of sulfur-oxidizing
bacteria operate at different stages of the oxidative process,
as was observed in field studies where tailings oxidation occurred
under natural conditions, suggesting that microbiological tests
performed for laboratory studies are reflective of field conditions.
Keywords: Kidd Creek; Canada; Tailings; Humidity cells; Laboratory
weatheringx
1. Introduction
2. Materials
3. Methods
@3.1. Humidity cell procedure
@3.2. Microbiological analyses
4. Results and discussion
@4.1. KC sample results
@4.2. KCJ results
@4.3. Metal mobility (As, Cd, Co, Cr, Cu, Ni, and Zn)
@4.4. Microbiological study
5. Conclusions
Acknowledgements
References