Near-field optical examination of potassium n-butyl 2 xanthate / chalcopyrite flotation products

The present study introduces scattering-type scanning near-field infrared optical nanospectroscopy (s-SNIM) as a valuable and well-suited tool for spectrally fingerprinting n-butyl xanthate (KBX) molecules adsorbed to chalcopyrite (CCP) sample surfaces. The collector KBX is well known to float CCP and is used in beneficiation. We thus identify KBX molecules both by IR optical far and near field techniques, applying attenuated total internal reflection Fourier-transform infrared spectroscopy (ATR FT-IR) in comparison to s-SNIM, respectively. The major KBX band around 880 cm−1 is probed in s-SNIM using both the tunable free-electron laser FELBE at the Helmholtz-Zentrum Dresden-Rossendorf, Germany and CO2 table-top laser illumination. We then are able to monitor the KBX agglomeration in patches of < 500 nm in diameter at the CCP surface, but equally to nanospectroscopically identify the presence of KBX molecules down to the 10−4 M concentration.