Flotation separation of chalcopyrite from galena using locust bean gum as a selective and eco-friendly depressant

Separation of chalcopyrite from galena in a low-alkaline environment is a critical technological process. This study explores the mechanism of the selective flotation depression effect of locust bean gum (LBG) toward galena. This natural polymer is applied for the first time to improve the selectivity of chalcopyrite/galena flotation. After the addition of 5-mg/L LBG at pH 8.0, the recovery of galena using sodium butyl xanthate as a collector drops below 10%, whereas the recovery of chalcopyrite remains over 80%. The selectivity of LBG toward galena is further characterized by adsorption tests, zeta potential measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The interaction mechanism that drives the adsorption process may be the hydrogen bonding between the hydroxylated mineral surface acting as a Bronsted acid and -OH groups from LBG polymer acting as a Bronsted base.