Impact of geological origin on flotation separation of apatite from dolomite using β-naphthyl sulfonate formaldehyde condensate as depressant

Abstract Under the same flotation conditions, the floatability of apatite is different with respect to geological origin. In this study, we tried to establish the relationship between geological origin and the floatability of apatite from the aspect of chemical compositions. Apatite minerals from igneous, sedimentary metamorphic and sedimentary deposits have been selected for flotation tests and a series of analyses including zeta potential tests, adsorption measurements and XPS analysis. β-naphthyl sulfonate formaldehyde condensate (NSFC) was used as the depressant in this work owing to its low cost as well as its excellent selectivity towards dolomite mineral. The flotation results demonstrate that NSFC showed a strong affinity towards dolomite rather than apatite. However, under the same flotation conditions, the floatability of apatite is highly affected by geological origin. The floatability always follows this given order: sedimentary apatite＞igneous apatite＞sedimentary metamorphic apatite. Combined with the results obtained from zeta potential measurements and XPS analyses, the adsorption of NSFC on these apatite surface is specific adsorption. Moreover, the larger amount of replacement of calcium by iron on apatite surface could result in a stronger formation of chemical bonds between iron elements and sulfo groups, thereby enhancing the hydrophilicity of apatite and consequently reducing its floatability in response.