Descriptor-Based Explorations on Flotation of Metal Sulfides Using Density Functional Theory Calculations

• Author / Creator

  Tao, Hongbiao

• Descriptor-based computational studies hold great promise for a more efficient optimization strategy for froth flotation of metal sulfides. To achieve this, fundamental insights into the ligand–metal sulfide interaction mechanism and identification of an effective descriptor possessing a predictive power toward the ultimate flotation index are highly desired. In this thesis, we have focused on understanding the trends in catalytic activity of metal sulfides for the oxygen reduction reaction (ORR) and the relative hydrophobic functionality of ligands toward metal sulfide using density functional theory (DFT) calculations. Thermodynamic calculations along the ORR elementary steps reveals that the catalytic activity trend of metal sulfides for ORR relates to its binding affinities toward ORR intermediates. This eventually led to the establishment of the S-3p band center as the descriptor linking the intrinsic attribute of metal sulfides with the corresponding catalytic ability. This descriptor also permits accurate prediction of the type of the anodic reaction product (X2 or MX2) between metal sulfide and xanthate. Regarding the surface hydrophobization of metal sulfides (galena and sphalerite), it is demonstrated that the chemical bond between the commonly used S/O-terminated ligands and metal sulfide is essentially ionic with limited covalency. This is in stark contrast to the conventional perception of these bonds. Moreover, instead of the generally used binding energy concept, we proposed that the electronegativity of ligand captures the relative ligand–metal sulfide bond ionicity, and it can potentially serve as the descriptor with respect to the hydrophobic functionality of the ligands toward metal sulfides. This study, therefore, further advanced our understandings on the catalytic activity of metal sulfides for ORR, shed light on the intrinsic ligand–metal sulfide binding mechanism and provided the thought-provoking descriptors.

• Subjects / Keywords

  • Density Functional Theory calculations
  • Sulfide Minerals
  • Flotation

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-5nqf-x822

• License

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