In situ Raman investigation of dissolved constituent and its evolution in pulp during Zn-S selective flotation with two-step pulp regulation

A new method to determine composition of sphalerite without secondary pollution based on CIELAB color space

“…Raman spectra of the six ZFSs are shown in Figure 2D, which are similar to those reported in the literature 7 . The Raman spectrum is split into two fundamental modes: the longitudinal optical (LO) mode at ∼349 cm −1 (the vibrations are parallel to the exciting light) and the transverse optical (TO) mode at ∼273 cm −1 (perpendicular vibrations) 7,10,11 . In terms of atom bonding, the LO mode (349 cm −1 ) was assigned to the Zn–S vibration, 7–10 while the Raman lines at 298 cm −1 were assigned to the Fe─S vibration mode, both cations being in tetrahedral coordination 21 .…”

“…Meanwhile, Fe–S bond is shorter than Zn–S bond, further strengthening the interaction between Fe and S atoms and causing S atoms bonded to Fe atoms to shift toward Fe atoms (as shown in Figure 2C). 10 Therefore, in terms of geometric structure, the crystal structure becomes more compact with increasing Fe content. Notably as the number of Fe atoms replacing Zn atom increases and the Fe content increases, the color of sphalerite samples darkens.…”

“…7 The Raman spectrum is split into two fundamental modes: the longitudinal optical (LO) mode at ∼349 cm −1 (the vibrations are parallel to the exciting light) and the transverse optical (TO) mode at ∼273 cm −1 (perpendicular vibrations). 7,10,11 In terms of atom bonding, the LO mode (349 cm −1 ) was assigned to the Zn-S vibration, [7][8][9][10] while the Raman lines at 298 cm −1 were assigned to the Fe─S vibration mode, both cations being in tetrahedral coordination. 21 If the LO mode is the fundamental vibration of M─S bonds, one notices that the former shifts to wavenumbers that are lower when M═Fe and higher when M═Zn.…”

“…9 The second series of methods relies on discerning the characteristic spectral lines generated by internal electronic transitions induced by absorbed radiation energy, which facilitates direct and swift identification of the target element content in the mineral. Prominent techniques of this category include Raman spectroscopy, 10 scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), 11 X-ray fluorescence spectroscopy (XRF), 12 and laser-induced breakdown spectroscopy (LIBS). 13 Most previous studies have only used two or three methods to determine Fe or Zn contents in natural sphalerite, while rarely considering secondary pollution or damage to human health caused by different analysis methods.…”