Inhibited mechanism of carboxymethyl cellulose as a galena depressant in chalcopyrite and galena separation flotation

Abstract

Carboxymethyl cellulose (CMC) is a highly efficient, nontoxic, and biodegradable depressant in Cu-Pb separation. However, poor understanding of the interaction mechanism has hindered the application of CMC in this separation process. Herein, galena was entirely inhibited by 250 mg·L−1 CMC at pH above 10, with minor effects on chalcopyrite flotation. As confirmed in zeta potential tests, CMC adsorbed much more easily to galena than chalcopyrite. The adsorption kinetics of CMC on galena was best described using a pseudo-second-order model dominated by chemisorption. In the presence of CMC, 74.4% of the electrochemical reaction sites on galena were inhibited and the resistance of the galena electrode surface film dramatically increased from 3838.7 to 17547.5 Ω·cm2. The likely mechanism of CMC adsorption on galena is competitive adsorption between CMC and sulfate to Pb2+.