Flotation separation of molybdenite from talc using carrageenan as depressant

Abstract

Due to the strong natural floatability of molybdenite and talc, conventional flotation depressants are difficult to separate these two minerals. As a common depressant, starch has a strong inhibitory effect on both minerals (Castro et al., 2016), while sodium carboxymethyl cellulose has a weak inhibitory effect on both minerals (Chen et al., 2024). Therefore, selecting a proper depressant is the key for achieving the efficient flotation separation. This study investigated the flotation separation of talc and molybdenite using carrageenan as the depressant and sodium butyl xanthate (SBX) as the collector. The micro-flotation test results showed that carrageenan exhibited a strong depressing effect on both talc and molybdenite, and even stronger on molybdenite. However, molybdenite could achieve flotation after adding SBX, while talc was still suppressed. In addition, it was observed that the recovery of molybdenite by adding SBX first was higher than that of adding carrageenan first. A concentrate with a molybdenum grade of 50.64% and recovery of 87.34% was obtained in the artificial ore flotation with the initial grade of 28.52%. The adsorption mechanism of carrageenan on the surfaces of molybdenite and talc was studied using contact angle testing, adsorption capacity testing, zeta potential measurement, Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS) analysis, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analysis. It was concluded that carrageenan physically adsorbs on both mineral surfaces, whereas SBX adsorbs selectively on the surface of molybdenite and competes with carrageenan for adsorption.