Fundamental aspects from Bayovar phosphate ore concentration

摘要

Two steps of reverse flotation of silicates with seawater using amidoamine as collector (107mg/L) at natural pH yielded a concentrate from Bayovar phosphate ore with 30% of P_2O_5 grade and metallurgical recovery of 90%. Fundamental studies were performed with pure minerals (apatite/feldspar), salty water and flotation reagent system at pH 8. The formation of precipitates composed by amidoamine and anions from salty water explained the good selectivity. Contact angles were measured to calculate surface energy of solids and free energy of adhesion for apatite/amidoamine precipitate and feldspar/amidoamine precipitate , indicating attraction between particles of apatite/precipitate and feldspar/precipitate, preferably for feldspar. Curves of interaction energy of apatite/ aminoamide precipitate and feldspar/ aminoamide precipitate versus distance between particles (l-20nm) were also built (using DLVO/X-DLVO theories). Hence, the contribution of Lifshitz-van der Waals is the most relevant energy comparing with electrostatic and acid-base. Besides, the interaction energy for feldspar/aminoamide precipitate presented higher magnitude than apatite/precipitate that could explain the selectivity of apatite/feldspar.