States of coadsorption for oleate and dodecylamine at selected spodumene surfaces

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 558; pp. 313 - 321
• Main Authors: Zhu, Guangli, Wang, Yuhua, Wang, Xuming, Yu, Fushun, Miller, Jan D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.12.2018
• Subjects: Collector mixture; DFT calculation; Flotation; SFVS; Spodumene; DFT calculation; Flotation; Collector mixture; Spodumene; SFVS
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2018.08.083

[Display omitted] In our latest study, it was reported that the effective flotation separation of spodumene from feldspar could be achieved using a mixture of the anionic collector, sodium oleate (NaOL) and the cationic collector, dodecylamine hydrochloride (DDA). This study is an extension of the previous work to provide further details of the coadsorption and association states for the NaOL/DDA collector mixture at selected spodumene and feldspar surfaces using Fourier transform infrared spectroscopy (FTIR), sum frequency vibrational spectroscopy (SFVS), density functional theory (DFT) calculations, contact angle measurements, and micro-flotation experiments. An important finding from the results was significantly improved collector adsorption at the spodumene (001) surface with small addition of DDA which was responsible for improved spodumene flotation using NaOL as the dominating collector. In the absence of DDA, oleate adsorbed as a well packed monolayer at the spodumene (110) surface, while poor adsorption of oleate with gauche defects was observed at the spodumene and feldspar (001) surfaces. A certain amount of DDA significantly enhanced the collector adsorption at the spodumene (001) surface, but had little or no effect on adsorption at the spodumene (110) surface and the feldspar (001) surface. Under these circumstances, an excellent separation of spodumene from feldspar can be achieved, as confirmed by contact angle and micro-flotation results. On the other hand, good adsorption and ordered structures of DDA and its dominative mixtures were observed at all selected surfaces. DFT calculation indicates that the association of DDA ion with oleate is preferred and accounts for the variations in collector adsorption states at these selected surfaces.