Application of a new depressant dithiocarbamate chitosan in separation of chalcopyrite and molybdenite

The application of a new depressant called dithiocarbamate chitosan (DTC-CTS) in flotation separation of chalcopyrite and molybdenite was firstly tested in present work, and the depression mechanism of DTC-CTS was investigated by contact angle measurement, Fourier Transform Infrared Spectrometer (FTIR) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The flotation test result showed that chalcopyrite could be depressed well by DTC-CTS in the Cu-Mo mixed system. Under the optimum condition of DTC-CTS dosage 0.8 mg/L, kerosene 20 mg/L, methyl isobutyl carbinol (MIBC) 20 mg/L and pH = 6, a Mo concentrate with Mo grade 54.86% and recovery 88.84% can be obtained from the Cu-Mo mixture, and this concentrate had a very low Cu grade of 3.37% with 9.65% recovery. Contact angle measurement results showed that the contact angle of chalcopyrite surface significantly decreased from 80.2° to 62.36°, while that of molybdenite decreased slightly from 71.63° to 67.82°. FTIR analysis showed that the peak of -NCSS shifted from 1446.18 cm−1 to 1459.52 cm−1 in the IR spectra of chalcopyrite after DTC-CTS treatment. It was indicated that DTC-CTS is easier to adsorb on chalcopyrite than molybdenite, and such a result is consistent with Tof-SIMS test. All these details have established that DTC-CTS strongly adsorbs onto the chalcopyrite surface mainly via the head group –NCSS bonding with the metal atoms on chalcopyrite surface. Then, the hydrophilic of chalcopyrite could be increased, which further results in the separation of chalcopyrite and molybdenite.