Understanding the Flotation Separation of Fluorite from Bayan Obo Deposits Using Phthalic Acid

The rising global demand for fluorite has spurred interest in utilizing coassociated fluorite resources. This study explores using phthalic acid (PA) as a collector to enhance flotation performance for coassociated fluorite in the Bayan Obo Nb-REE-Fe ore in China. The real ore was characterized by a low grade, multiple mineral types, fine intergrowths, and complex interlocking and inclusion relationships among the minerals. The flotation of real ore with PA as a collector yielded high-grade fluorite concentrate suitable for use in the production of anhydrous hydrogen fluoride (AHF). Microflotation tests showed PA's collecting capacity for bastnaesite and fluorite in weakly acidic to weakly alkaline conditions. Zeta potential shifts indicated the adsorption of PA on the surfaces of bastnaesite and fluorite, with electrostatic interactions playing a significant role. Fourier transform infrared spectroscopy (FTIR) revealed absorption peaks for carboxyl groups and benzene ring CC skeletons, while X-ray photoelectron spectroscopy (XPS) analysis showed shifts in binding energies of C 1s, O 1s, Ca 2p, and Ce 3d, confirming chemical bonding between PA and minerals. These findings expand PA's application in flotation and offer insights for efficient coassociated fluorite resource utilization in the Bayan Obo deposit.