Abstract: The flotation behaviour and mechanism of bastnaesite with N-hydroxyl phthalicimide were investigated by ξ-potential measurement,infrared spectrum and quantum chemistry calculation.The results show that 3 oxygen atoms from N-hydroxyl phthalicirnide chelate the rare earth ions on the surface of bastnaesite to form double five-chain O=C-N-O- RE(Ⅲ)-O chelate which is chemically adsorbed on the surface of bastnasite,thus making N-hydroxyl phthalicimide an effective collector for bastnaesite.

Key words: N-hydroxyl phthalicimide, flotation, bastnaesite, collector