Abstract

The aim of this study was to assess arsenic (As) mobilization in an active tailings dam through mineralogical and geochemical characterization study. Arsenite is the predominant As species in the dam with more than 50% of the arsenic bound to the organic fraction. Pyrite and arsenopyrite are the principal opaque minerals remaining in the tailings with relic grains showing rims of oxidation (hematite/goethite). Illite, kaolinite and carbonates act as pH buffers and consume the acid generated during pyrite oxidation and raise the pH to near neutral measured in the tailings dam. At near neutral conditions As is mobilized, which likely combines with the Fe and Ca oxides formed to form ferric-calcium arsenates and deposited in the tailings dam. Some As appear to equilibrate with atmospheric CO₂ and are converted into calcium carbonates with release of arsenic into solution.

Keywords:

Arsenic, arsenopyrite, pyrite, tailings,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.