Abstract: The application of phthalic acid, a new chelating collector, in the flotation separation of malachite (Cu₂CO₃(OH)₂) and quartz (SiO₂) was studied. The flotation performance of phthalic acid on malachite and quartz was evaluated by micro-flotation test. The results show that phthalic acid has strong adsorption and selectivity for malachite and can effectively separate malachite and quartz. Using phthalic acid as collector, the separation effect of artificial mixed minerals was good at pH 9 and dosage of 80 mg/L. And the recovery of malachite and quartz was 70% and 5%, respectively. The adsorption mechanism was studied by contact angle, SEM-EDS, Zeta potential, adsorption capacity, Fourier Transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that the strong chemical adsorption between phthalic acid and Cu²⁺ ions on malachite surface occurred. After treatment, the hydrophobicity of malachite was greatly improved and the selectivity was good. It can effectively separate malachite and gangue minerals.