The selective adsorption of xanthan gum on dolomite and its implication in the flotation separation of dolomite from apatite

In this work, xanthan gum (XG) was exploited as a novel dolomite depressant in the flotation separation of apatite from dolomite in sodium oleate system. The flotation performances and adsorption mechanism of XG towards apatite and dolomite were studied through flotation tests, adsorption capacity measurements, micro-heat tests, atoms density calculations and surface characterizations. Flotation results revealed that XG exhibited strong depression effect on dolomite but barely influenced the flotation of apatite. The results of zeta potential, infrared spectroscopy analysis, adsorption capacity measurements and micro-heat tests proved that XG trended to adsorb on dolomite other than apatite, which hindered the adsorption of NaOL on dolomite and rendered the surface hydrophilic. Atom density calculations indicated that the preferential adsorption of XG on dolomite was due to much more dense and active Ca sites on dolomite surface than that of apatite. XPS results suggested that XG was strongly adsorbed on dolomite surface by means of chelation between -COOH or -OH groups within XG and Ca sites on dolomite, while it was weakly adsorbed on apatite by hydrogen bonding between -OH groups within XG and F atoms on apatite surface.