The effect of calcium hypochlorite on the adsorption of diethyldithiocarbamate (DDTC) on the surface of molybdenite and bismuthinite

Abstract

In this paper, the effect mechanism of calcium hypochlorite on the adsorption of the collector DDTC on the surface of molybdenite and bismuthinite was explored. The single mineral flotation test showed that calcium hypochlorite had significant inhibition on the flotation behavior of bismuthinite, but had no similar effect on that of molybdenite. The results of FT-IR spectra and contact angle measurement indicated that the collector DDTC was not able to adhere to the bismuthinite surface treated with calcium hypochlorite, but could adhere to the molybdenite surface treated with the same way. Synthesizing the results of electrochemical test, thermodynamic analysis, Raman spectra, and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) test, it could be confirmed that calcium hypochlorite could react on the surface of bismuthinite and molybdenite, and the reaction on the bismuthinite surface first produced Bi3+ and Cl-, which continued to react in solution and finally formed BiOCl precipitation, while the reaction on the molybdenite surface formed soluble components, which dissolved into the solution. Therefore, the hydrophilic BiOCl precipitation covered the bismuthinite surface, hindering the adsorption of DDTC, while the soluble components produced on the molybdenite surface entered the solution without affecting its surface wettability and collector adsorption, which maybe was the root cause of the selective depression of calcium hypochlorite.