Abstract: The influence of three different collectors sodium oleate， styrene phosphonic acid and salicylhydroxamic acid on fine cassiterite flotation are investigated by conducting a series of micro-flotation tests， and the mechanism of styrene phosphonic acid collecting cassiterite is assessed by Zeta potential determination， atomic force microscopy and X-ray photoelectron spectroscopy. The experiment results indicates that sodiumoleate， styrene phosphonic acid and salicylhydroxamic acid can improve the floatability of cassiterite in the flotation of fine cassiterite， and the collecting capability of the three collectors towards fine cassiterite decreases in the order as follows: styrene phosphonic acid＞sodium oleate＞salicylhydroxamic acid. The styrene phosphonic acid mainly chemically adsorbs the surface of cassiterite， which forms many selective peak-like adsorption points on the surface of cassiterite and moves the Zeta potential of the surface of cassiterite to the negative direction. The two O atoms losing H+ on the phosphonic acid group can be combined with the Sn atom on the surface of cassiterite， which causes the styrene phosphonic acid is stably adsorbed on the surface of cassiterite.

Key words: Cassiterite, Flotation, Collector, Styrene phosphonic acid, Atomic force microscope