Flotation of cassiterite using alkyl hydroxamates with different carbon chain lengths: A theoretical and experimental study

Abstract

The effects of five alkyl hydroxamates (hexyl hydroxamate (C6), octyl hydroxamate (C8), decyl hydroxamate (C10), dodecyl hydroxamate (C12) and tetra-decyl hydroxamate (C14)) with different carbon chain lengths on the flotation behaviour of cassiterite have been studied by using theoretical and experimental methods. Microflotation tests results showed that increasing the carbon chain length improved the collecting abilities of hydroxamates for cassiterite under acidic to weak alkaline conditions. Adsorption measurements suggested that the adsorption amount of hydroxamic species on the cassiterite surface increased along with carbon chain length. Density functional theory (DFT) calculation results indicated that alkyl hydroxamates with a longer carbon chain have lower electronic stabilities and larger dipole moments. In the absence of H2O molecules, hydroxamates with longer carbon chains easily absorbed on the SnO2 surface by chelating 6-membered rings.H2O molecules could spontaneously adsorb on the SnO2 surface. Hydroxamates adsorbed on the hydroxylated SnO2 surface via hydrogen bonding interaction. X-ray photoelectron spectroscopy (XPS) analysis revealed that hydroxamates adsorbed on cassiterite through physical interaction, thereby suggesting that the computational simulation results are reliable.