Flotation of silicate minerals physico-chemical studies in the presence of alkylamines and mixed (cationic/anionic/non-ionic) collectors

Abstract: The mechanism of adsorption of long chain alkyl primary amines and, co-adsorption of amines and alcohols on silicate minerals (quartz and feldspar) were studied using FTIR (DRIFT and IRRAS) and XPS spectroscopy methods. The spectroscopy data were correlated with zeta-potential and Hallimond flotation results. The effect of alkyl chain length of mixed collectors in adsorption at solid/water interface is also examined. In addition, the underlying mechanism of the reported mixed cationic/anionic collector scheme for selective feldspar flotation from quartz is delineated through flotation, zeta-potential and infrared spectroscopy studies. Furthermore, the mixed collector system is applied for a successful separation of albite from Greek Stefania feldspar ore. For the first time, it was shown from infrared spectra that the amine cation forms strong hydrogen bonds with the surface silanol groups. The XPS spectra revealed the presence of molecular amine together with the protonated amine on silicate surface. Based on these observations, a model of successive two-dimensional and three-dimensional precipitation was suggested to explain amine adsorption on a silicate surface. The co-adsorption of long chain alcohols or sulfonates with amine cations leads to formation of a closer packed surface layer with synergistic enhancement of amine adsorption. The enhanced adsorption and hence higher flotation recoveries is discussed in the light of our experimental results.