Kinetic studies of amyl xanthate adsorption and bubble attachment to Cu-activated sphalerite and pyrite surfaces

Kinetic studies of bubble attachment and amyl xanthate (AX) adsorption to CuSO4 (Cu) activated sphalerite and pyrite surfaces were investigated by a novel in-situ approach with high-speed video microscopy (HSVM) and cryogenic X-ray photoelectron spectroscopic (Cryo-XPS). The drainage rate (DR) of thin films between the bubble and the surfaces was linked with the rate of AX adsorption onto the mineral surfaces. The single minerals studies revealed that the drainage (and adsorption) rate on polished pyrite was higher than on polished sphalerite after treatment with AX. However, the AX adsorption rate exhibited a higher value on the Cu-activated sphalerite than on the Cu-activated pyrite, indicating different surface components formed on the minerals surfaces and their different abilities to uptake Cu ions. Modeling AX adsorption rate on the unactivated and activated minerals by a pseudo-first order rate equation revealed the dependence of the drainage (and adsorption) rate on the initial AX concentration and the available active sites on the minerals surfaces. For the two minerals system, AX treatment results showed a significant drop in the adsorption rate of AX on the activated sphalerite with increasing the sphalerite to pyrite surface area ratio from 1:1 to 1:6. It confirmed the dependence of the AX adsorption rate on the available active sites on the minerals. Cryo-XPS confirmed that Cu-xanthate complex on the Cu-activated sphalerite and dixanthogen on the Cu-activated pyrite were the dominant surface components after treating with AX. It showed a selectivity of AX on the activated sphalerite with chemisorbed Cu-xanthate formation. However, consumption of AX with Cu-activated pyrite in the form of dixanthogen as well as Cu- or Fe-xanthate complexes were inevitable, especially when the available pyrite surface area was high in the mixed mineral system.