Understanding the interactions of thiophosphorus collectors with chalcopyrite through DFT simulation

Density functional theory simulations were performed to study the adsorption mechanism of four different thiophosphorus collectors including diethyl dithiophosphate (DEDTPA), diethyl dithiophosphinate (DEDTPI), diethyl monothiophosphate (DEMTPA) and diethyl monothiophosphinate (DEMTPI) on chalcopyrite (1 0 0) and (1 1 0) surfaces. DFT revealed a major reconstruction of sulfur and metal exposed chalcopyrite (1 0 0) surfaces after cleavage. This results into formation of disulfide dimers on the surface and migration of copper and iron inwards with respect to bulk with formation of new Fe Fe, Cu Fe and Cu Cu bonds in the latter after relaxation. Thiophosphorus collectors chemisorb on the sulfur-exposed chalcopyrite (1 0 0) surface through formation of a monodentate covalent bond between sulfur atom from the collector polar head and surface-unsaturated sulfur atom. However, the interaction of the collectors with the metal exposed chalcopyrite (1 0 0) is through physisorption. The interaction of chalcopyrite (1 1 0) surface with thiophosphorus collectors involves bidentate chemical bonding between surface copper and iron atoms and sulfur and/or oxygen atoms of the collector polar-head.