Separation and beneficiation of low-grade phosphate rock: A comprehensive review

The depletion of high-grade phosphate reserves has necessitated the efficient beneficiation of low-grade phosphate rock (LGPR) to ensure a sustainable phosphorus supply. LGPR beneficiation is mainly constrained by fine dissemination and complex gangue assemblages. This review adopts a process-mineralogy perspective, linking mineralogical features to liberation behavior, separation routes, and industrial applicability. Sedimentary LGPR exhibits fine-grained francolite intergrown with carbonate or siliceous gangue, severe sliming, and poor phosphate-carbonate surface selectivity. Igneous LGPR contains coarser fluorapatite but requires integrated removal of silicate, Fe/Ti oxides, carbonate, and sulfide impurities. Liberation and dispersion are prerequisites for separation. Accordingly, mechanical, physical, and chemical strategies for addressing fine dissemination and slime interference are first discussed. Beneficiation routes are then evaluated across rock types by target impurities, particle-size range, separation performance, technological maturity, and environmental impacts. For sedimentary LGPR, flotation-centered separation systems are evaluated, supplemented by classification, gravity separation, sensor-based sorting, electrostatic separation, calcination, and acid leaching. For igneous LGPR, flotation and magnetic separation routes are reviewed. Industrial practice remains concentrated in mature processes, with economic viability governed mainly by grinding energy, reagent consumption, water recycling, P2O5 losses, and residue management rather than feed grade alone. Future advances should focus on rock-specific flowsheet design, intelligent process control, by-product recovery and residue valorization.