A copper PEEM image of NaEX conditioned Cp sample is shown in
Fig. 5a. Normalised Cu L3-edge NEXAFS spectra collected from12 different
regions of interest (ROI) are shown in Fig. 5ai and aii. TEY Cu L3 spectra
represented in Fig. 5ai show a leading absorption peak at 932.6 eV
along with a small peak at 933.8 eV. The peak at 932.6 is attributed to
CuI in Cp [17,18,31,44], while a broad unresolved shoulder peak at
933.8 eV is indicative of either adsorbed CuEX or CuI oxide. Given the
UV–vis data presented in Fig. 2 indicates the loss of EX from solution
and the ToF-SIMS data shown in Fig. 4 shows the presence of EX at
the surface of Cp under these conditions. The broad unresolved peak at 933.8 eV is likely due to adsorbed CuEX. The spectra represented in
Fig. 5aii shows a comparatively sharp absorption peak at 931.8 eV
representing unoxidised chalcopyrite with no peak near 933.8 eV for
CuI oxides. No evidence of a CuII peak near the pre-absorption edge i.e.
between 930 and 931.3 eV was observed. For the first time PEEM has
been successfully used to study the variation in surface copper speciation
on mineral particles of size d80 of 20 μm under different mineral
pulp conditions.