Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy Characterization Of Oxide Ores During Thiosulfate-Mediated Gold Leaching

An applied approach for in situ characterization of oxide ore samples exposed to a thiosulfate-based leaching solution with shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) is discussed. Differences in passive layer growth during thiosulfate leaching were observed in the SHINERS spectra between the untreated and pressure oxidation (POX)-treated oxide ore samples received from Barrick Gold Corporation. The SHINERS spectra revealed that the passive layer at the untreated oxide ore-electrolyte interface contains metal sulfides and significant quantities of polysulfide chains (Sn/Sn2-) of variable lengths after longer exposure to the leaching solution. However, the passive layer observed with the POX-treated sample was found to be predominantly metal sulfides with only a small quantity of polysulfide chains. From these results, it was concluded that the POX pretreatment process may successfully destroy or inactivate minerals found in the ore that are responsible for catalysing thiosulfate decomposition into polysulfides which results in low gold extraction efficiencies. Copyright (c) 2016 John Wiley & Sons, Ltd.