Shengjia Zeng, Jun Li, Russell Schumann, Roger Smart
Levay& Co.; University of South Australia, Adelaide, South Australia, Australia.
Minerals and Materials Science & Technology, Mawson Institute.
DOI: 10.4236/cweee.2013.22B009   PDF    HTML     4,715 Downloads   7,873 Views   Citations

Abstract

Acid mine drainage (AMD)and toxic metal release generated by oxidation of sulphide minerals, particularly pyrite, in mine wastes,are a critical environmental issue worldwide.Currently, there are many options to diminish sulphide oxidation including barrier methods that isolate pyrite from oxygen or water, chemical additives and inhibition of iron-oxidizing bacteria. This study focuses on understanding the rolethatsilicate and pH conditions play in the formation and stabilisation ofpyrite surface passivation layers found in lab and field studies.The results from pyrite dissolution tests under various conditions showed that the pyrite oxidation rate has been reduced by up to 60% under neutral pH with additional soluble silicate. Solution speciation calculation predicted that crystalline goethite is formed in the experiment without silicate additionbutan amorphous iron hydroxide surface layer is stabilizedby the addition of the silicate, inhibiting goethite formation and continuing pyrite oxidation.This coherent, continuous amorphous layer has been verified in SEM.

Keywords

Acid Mine Drainage; Pyrite; Passivation Coating; Silicate

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Conflicts of Interest

The authors declare no conflicts of interest.

References

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