REACTIONS OF AQUEOUS AU1+ SULFIDE SPECIES WITH PYRITE AS A FUNCTION OF PH AND TEMPERATURE

The reactivity of aqueous Au1+ sulfides with FeS2 at pH = 3 and 6 for temperatures of 25 and 90 degrees C has been investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with en ergy dispersive X-ray analysis (SEM/EDXA), and static secondary ion ma ss spectrometry (SSIMS). The presence of both Au1+ and metallic Au are observed upon the FeS2 surface. We show that Au deposition is increas ed at elevated pH or temperature; but the amount of Au deposited is fa r lower than in AuCl4- solutions owing to the greater stability of Au( SH)(x)(1-x) complexes. This is the first evidence of Au1+ pyrite from bisulfide solutions using XPS.