DFT-D Investigation of Dithiocarbamate, Thionocarbamate, Mercaptobenzothiazole, and S-Triazine Collector Adsorptions on Pentlandite (Fe5Ni4S8) Mineral Surface

With the increasing demand for nickel, relentless efforts have been made to find alternative and highly selective collectors for recovering pentlandite. This study employed density functional theory (DFT) with dispersion correction to examine the interactions of iron-rich pentlandite (Fe5Ni4S8) mineral surface with various collectors: S-allyl-N-diethyl-dithiocarbamate (ADEDTC), O-isopropyl-N-diethyl-thionocarbamate (IPDETC), sodium mercaptobenzothiazole (SMBT), and sodium-2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT). The plane surface of (311) proved to be the most stable surface with a surface energy of 1.48 J.m−2, aligning well with the experimental X-ray diffraction (XRD) results and morphology. Adsorption simulations were performed on both Ni and Fe atoms of the plane surface of (311). ADEDTC exhibited the most exothermic adsorption energy of −460.58 kJ.mol−1, compared to SMBT (−249.59 kJ.mol−1), IPDETC (−161.01 kJ.mol−1), and SDTBAT (−352.48 kJ.mol−1). The adsorption strengths followed the order ADEDTC > SMBT > SDTBAT > IPDETC. Importantly, these collectors showed a preferential adsorption on the Ni atoms over Fe atoms, indicating selectivity towards Ni sites on the pentlandite mineral surface. These findings suggested that ADEDTC was the most effective collector for flotation applications involving pentlandite. As such, ADEDTC could potentially replace commonly used collectors or be used as a co-collector in the recovery of pentlandite minerals.