The comparison of N-containing collectors on selectivity and froth stability in reverse flotation of silicate minerals from fluorapatite

In this study, four N-containing collectors were compared systematically to study the flotation selectivity, froth layer stability and economic cost in reverse flotation of silicate minerals from fluorapatite. The adsorption of collectors were studied by zeta potential and x-ray photoelectron spectroscopy (XPS) measurements. Froth stability of the slurries with collectors was characterized through froth image and water recovery analysis. The flotation of pure fluorapatite, quartz, mica and raw phosphate ore gave that oleyl amine (OA) and N-(2-hydroxyethyl)-dodecane amide (HEDA) had better selectivity than dodecyl amine (DDA). It was found that the physisorption of OA and HEDA associated with the silicate mineral surfaces through hydrophobic bonding to form hemimicelles. Interestingly in octyl-hydroxamic acid (OHA) flotation, the best selectivity in reverse flotation of silicate minerals from fluorapatite was obtained, because of the chemisorption of O atoms on Al atoms through chelating rings. For froth stability, OA and HEDA induced a denser froth layer than DDA. In OHA flotation slurry, the individual bubbles were larger and easier to coalesce, leading to the lowest water recoveries and froth stability. This study might provide a further understanding on the N-containing collectors in reverse flotation of silicate minerals from fluorapatite.