Novel and Efficient Organic Phosphonic Acid Inhibitor to Achieve the Flotation Separation of Apatite and Dolomite

In this research, 2-hydroxy phosphonyl acetic acid (HPAA) was employed as an environmentally friendly inhibitor to facilitate the flotation separation of apatite from dolomite. The results of the microflotation test indicated that 15 mg/L HPAA reduced the recovery of dolomite from 82.55% to 21.07%, while the recovery of apatite remained at 79.81%. The flotation test of artificial mixed ore showed that after adding HPAA, the grade of P₂O₅ in the mixed concentrate increased from 19.96% to 26.67%, and the recovery reached 75.88%. Adding Na₃PO₄·12H₂O to the slurry effectively mitigated the influence of interfering ions on the flotation separation of apatite from dolomite. The scanning results of atomic force microscopy showed that the adsorption density and adsorption height of HPAA on the surface of dolomite were both stronger than those on the surface of apatite. The results of X-ray photoelectron spectroscopy showed that HPAA reacted with the Ca and Mg sites on the surface of dolomite. Time-of-flight secondary ion mass spectrometry detected characteristic ion fragments of C₂O₆PCaMg⁺ on the surface of dolomite treated with HPAA, and the ion fragment intensifications of C₂O₆PCaH⁺ and C₂O₆PMgH⁺ were significantly enhanced. The calculation results of density functional theory showed that the configuration of HPAA is the most stable when it simultaneously adsorbs Ca and Mg ion sites on the surface of dolomite. There is electron transfer between O in the HPAA structure and Ca and Mg ions on the mineral surface, indicating that a chemical reaction has occurred between them. This research provides a theoretical basis for the design and development of green flotation inhibitors for phosphate rock.