Insight into the inhibition mechanism of carboxymethyl cellulose for flotation of dolomite and fluorapatite: Experimental and DFT studies

The flotation separation of dolomite and fluorapatite is difficult due to the similar surface properties. In this study, carboxymethyl cellulose (CMC) was introduced as a depressant for flotation of dolomite and fluorapatite, the adsorption mechanism of CMC on the mineral surfaces was clarified by DFT calculations, XPS analysis , zeta potential and contact angle measurements. The results showed that CMC exhibited a strong inhibitory effect for dolomite under alkaline conditions due to the surface adsorption. Compared with the adsorption of CMC on two Ca sites or two Mg sites of dolomite (104) surface, CMC preferred to simultaneously adsorb at Ca site and Mg site to form a more stable bridge adsorption, the two O in carboxyl group of CMC could bond with Ca and Mg to form chemical adsorption . However, CMC could not be adsorbed on the surface of fluorapatite, and the presence of CMC did not affect the adsorption of collector on fluorapatite surface to make it hydrophobic. Thus, CMC can be used as an alternative depressant for the selective flotation separation of dolomite and fluorapatite.