Thiolate layers on metal sulfides characterised by XPS, ToF-SIMS and NEXAFS spectroscopy

X-ray Photoelectron Spectroscopy in Mineral Processing Studies

“…Oxidation of sulfide minerals notably affects their hydrophobicity and floatability but flotation reagents play the main role in their recovery and separation [2,5,[8][9][10]18,22,[91][92][93][94]. Sulfhydryl collectors, particularly alkyl xanthates are the most common reagents [2,5,8,10], so we restrict this overview to xanthates as a representative example.…”

“…Application of surface-sensitive techniques to this field, which is necessary in order to gain insights into the surface composition and chemistry, however, faces with a number of difficulties. The X-ray photoelectron spectroscopy (XPS, also known as electron spectroscopy for chemical analysis ESCA) is a powerful method for surface studies in materials science, catalysis, and other areas [15,16], and is widely utilized for characterization of mineral surfaces and interfaces [10,[17][18][19][20][21][22][23][24].…”

“…Alternative techniques such as Auger electron spectroscopy (AES) [25,26] and secondary ion mass-spectrometry (SIMS, TOF-SIMS) [27] are less informative regarding chemical bonding and also require an ultra-high vacuum environment (UHV). X-ray absorption spectroscopy (XANES/EXAFS), infrared spectroscopy (ATR-FTIR) and Raman spectroscopy are not generally surface-sensitive and unable to determine the total surface composition [18,19,[22][23][24][28][29][30][31][32]. The photoelectron spectroscopy is based on the analysis of electrons emitted under X-ray irradiation from the core levels and the valence band in atoms of materials located in the near-surface region as a function of the binding energy (BE) [15].…”

“…The metal sulfides are the main source of base metals in nature, and are also of vivid interest for materials science. In comparison with the previous reviews of mineral surface studies [5][6][7][8][9][10][17][18][19][20][21][22][23][24], this contribution is focused on methodological aspects, modern trends and developments of XPS along with the limitations concerning elusive (volatile, unstable or buried) entities on sulfide minerals, and the techniques aimed at (quasi) in situ approach. Only some important papers from the XPS application history are overviewed here, and only selected results are discussed in detail as examples.…”

The effect of mixed thiol collectors on the flotation of galena

“…Hanson et al (1985) proposed that, in a binary xanthate-glycine system, the glycine encouraged greater adsorption of the xanthate due to the formation of metal glycinate complexes, which react with the xanthate and finally adsorb on the mineral surface. However, it is known that xanthate will adsorb in multiple layers onto a mineral surface and seems to need little encouragement from a co-collector (Goh et al, 2008).…”