Biooxidationhasbeensuccessfullyappliedinthefieldofrefractorygoldorepretreatment.Itreferstoaprocessthatusesacidophilicmicroorganismstooxidizeanddeterioratetheminerals,thusmakinggoldavailableforcyanidation.Acidithiobacillusferrooxidans(At.f),achemolithoautotrophic,acidophilic,moderatelythermophilicbacterium,isthemostcrucialmicroorganisminvolvedinbiooxidation.At.fcanobtainenergybyoxidizingferrousironsandreducedsulfurcompoundsintheminerals[1].Asatoxicmetalloidcarcinogen,arsenicisalwaysassociatedwithhydrothermalgolddeposits.Arsenicisfrequentlyfoundasarsenopyrite(FeAsS),realgar(As4S4),orpiment(As2S3)andinrefractorygoldores[2].
