LAUSR

Changes in mineral surface properties during grinding play a key role in flotation performance. ToF-SIMS surface chemical analytical studies have shown that flotation separation of sphalerite from chalcopyrite is significantly affected by the oxidation of metal species on the surface of sphalerite. The intensity of iron oxyhydroxyl species on the surface of sphalerite has a positive correlation with poor recovery of sphalerite. Given the link between the presence of oxide species on the surface of sphalerite and a lower recovery during Cu flotation, a laboratory study was initiated to evaluate the potential for sphalerite surface oxidation control and improve recovery through grinding. For the investigation, a ball mill which allowed for monitoring pulp chemistry during grinding was utilized to study the impact of grinding conditions on selective flotation of sphalerite. ToF-SIMS was used to identify and measure the variability in sphalerite surface species as a result of the different test parameters. Variable mill parameters include 2 types of grinding media, aeration conditions, addition of FeSO4, and altering the pyrite content in the feed ore. TOF-SIMS analyses of mill discharge samples identified higher intensities of iron oxyhydroxyl species on sphalerite surface subsequent to grinding with mild steel balls, in condition of aeration, use of FeSO4, and by increasing the pyrite content of the feed ore. The higher adsorption of iron oxyhydroxyl species on the surface of sphalerite should be consistent with the lower recovery. To verify this, bench scale flotation tests in the presence and absence of FeSO4 were performed; results correlated iron oxyhydroxyl species with the poor sphalerite recovery.