1-Hydroxydodecylidene-1,1-diphosphonic acid flotation of bastnäsite: Performance and mechanism.

The recommended hydrophobization mechanism of 1-hydroxydodecylidene-1,1-diphosphonic acid (HDDPA) towards bastnäsite [(Ce,La)CO 3 F]as well as the flotation separation and recovery of bastnäsite from its mixture with calcite. • 1-Hydroxydodecylidene-1,1-diphosphonic acid was used in bastnäsite flotation. • HDDPA achieved an efficient separation of bastnäsite from calcite at pH ∼8.0. • HDDPA3− was glad to replace the CO 3 2- of Ce(III) carbonates on bastnäsite. • The surface Ce(III) of bastnäsite bonded with the O atoms of HDDPA's O P(O)O. To separate and enrich rare-earth elements (REE) minerals from their ores through flotation process has become an attracting topic for REE's strategic position. In the present investigation, the floatability of bastnäsite [(Ce,La)CO 3 F] was explored by using 1-hydroxydodecylidene-1,1-diphosphonic acid (HDDPA) as a collector. The micro-flotation results showed that bastnäsite displayed an eminent floatability under pH 7.0–10.0, and HDDPA realized an efficient separation of bastnäsite from calcite at pH around 8.0. Zeta potential and solution chemistry inferred that at pH 7.5–9.3, HDDPA3− anions were glad to replace the CO 3 2- ions of Ce(Ⅲ) carbonates in/on bastnäsite interface, resulting in a high flotation recovery of bastnäsite. With increasing OH- concentration, the competition ability of OH- against HDDPA anion intensified, gradually the surface Ce(III) hydroxide species increased, and the floatability of bastnäsite reduced. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) recommended that the surface Ce(III) of bastnäsite interacted with the O atoms of HDDPA's O P(O)O group to generate a four membered ring configuration, which hydrophobized bastnäsite particles. [ABSTRACT FROM AUTHOR]