Effect of geological origin of apatite on reverse flotation separation of phosphate ores using phosphoric acid as depressant

[Display omitted] •Floatability of apatite is affected by geological origin under acidic environment.•Substitution of PO43− by CO32– is different with respect to geological origin.•Apatite with higher crystallinity exhibits lower dissolution rate.•The dissolved Ca2+ and Mg2+ ions deteriorate the floatability of apatite. Apatites of different geological origins exhibit different floatabilities under the direct flotation process. However, the floatability of apatite from different geological origins under reverse flotation, especially in acidic environments, has not yet been reported. In this study, sedimentary (SD), igneous (IG), and sedimentary metamorphic (SM) apatite minerals are chosen as raw materials to investigate the relationship between the geological origin and flotation behavior of apatite in acidic environments, by means of flotation tests and a series of analyses. The geological origin of apatite affects its solubility in an acidic environment. Furthermore, compared to apatite from IG and SM deposits, there is more substitution of PO43− by CO32– on apatite from SD deposits, which accelerates the dissolution of Ca2+ and Mg2+ ions from its surface, thereby causing fewer active sites to remain on its surface. Under the same phosphoric acid dosage, the floatability of the three apatite follows: IG > SM > SD.