Hydrophobicity of chalcopyrite with dithiophosphate and dithiophosphinate in electrochemically controlled condition

Dithiophosphinate–pyrite interaction: Voltammetry and DRIFT spectroscopy investigations at oxidizing potentials

The electrochemistry of dithiophosphinate (DTPI) adsorption on pyrite was investigated by cyclic voltammetry (CV) and diffuse reflectance infrared Fourier transformation (DRIFT) spectroscopy at oxidizing potentials under acid, neutral, and alkaline conditions. CV study showed that the mineral surface was covered by porous ferric oxyhydroxide species. Irreversible DTPI adsorption on the pyrite surface and inhibition of electron transfer to some extent were also observed from electrochemical work. Major collector species were determined from DRIFT spectroscopy study as adsorbed collector compound, DTPI degrees , and dimer of dithiophosphinate, (DTPI)2. Maximum adsorption density of DTPI was obtained in acid solution. It decreased sharply under neutral and alkaline conditions due to heavy surface oxidation at higher pH.

Voltammetric and drift spectroscopy investigation in dithiophosphinate–chalcopyrite system

The mechanism of dithiophosphinate (DTPI) adsorption on chalcopyrite was investigated by diffuse reflectance Fourier transformation (DRIFT) spectroscopy and by cyclic voltammetry (CV) at various pHs. CV experiments showed that the redox reactions occurred at a certain degree of irreversibility on the chalcopyrite surface in the absence of a collector due to preferential dissolution of iron ions in slightly acid solution and irreversible surface coverage by iron oxyhydroxides in neutral and alkaline solutions. In the presence of DTPI, CV experiments failed to identify the type of the adsorbed DTPI species and electrochemical processes occurring on chalcopyrite due to formation of an electrochemically passive surface layer preventing electron transfer. However, DRIFT spectroscopy tests showed this passive layer to be mainly CuDTPI + (DTPI)2. Both CV and DRIFT spectroscopy established that the activity of collector species decreased with increasing pH due to formation of stable hydrophilic metal oxyhydroxides on the chalcopyrite surface.