Depressing behaviors and mechanism of an eco-friendly depressant on flotation separation of cassiterite and fluorite

Abstract

Froth flotation has become the dominant technique for separating cassiterite and fluorite. However, due to the limited selectivity of conventional collectors, fluorite was always collected with cassiterite simultaneously in the absence of depressants, which could reduce the grade of concentrate and economic benefits. In this paper, galactomannan (GM) was used as a selective depressant to facilitate the separation of cassiterite and fluorite, and the separation effect was evaluated by the flotation experiments. The results showed that the flotation of cassiterite was significantly depressed while that of fluorite was nearly affected. Moreover, the adsorption mechanism of GM onto the two minerals was investigated by zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS) analyses. It was found that GM was adsorbed on cassiterite through chemisorption and the main active sites of cassiterite to react with GM were Sn. Meanwhile, the adsorption density of GM onto cassiterite was much more than that onto fluorite, which also further caused SPA could not be adsorbed onto the surface of cassiterite in the presence of GM. Therefore, GM could be utilized as a potential depressant for separation cassiterite and fluorite.