Phase inversion and wettability in testing the extender oil for the flotation of coarse potash ore fractions

• Main Author: Barroilhet Cahuas, Leonardo
• Language: English
• Published: University of British Columbia 2015
• Online Access: http://hdl.handle.net/2429/54778

The effects of amines on the phase inversion of oil/NaCl-KCl saturated-brine emulsions stabilized by KCl particles and on the wettability of KCl surfaces in brine were investigated. Contact angle at the oil/saturated-brine/KCl line of contact, interfacial tension at the oil/saturated-brine interface, and phase inversion measurements were performed to study the applicability of the phase inversion method in the selection of the extender oil(s) for subsequent coarse potash ore flotation tests. Two commercial amines, dodecyl and octadecyl, and two technical amines, TD and HTD, were tested as additives to oil in the preparation of the extender, and three hydrocarbons (cyclohexane, n-decane, and Diesel oil). The contact angle results demonstrated that amines adsorb onto KCl with a clear effect of the equilibration time. The increasing of contact angle with amine concentration was influenced by two equilibrium phenomena: a “fast equilibrium” resulting from the diffusion of large amine molecules to the interfaces and a “slow equilibrium” caused by dissolution/recrystallization of mostly NaCl fine crystallites onto KCl surfaces in saturated brine. This project discusses the existence of eight intermediate states that describe sequentially the changes in KCl wettability caused by the amine adsorption. Each state occurs at a particular amine concentration, which is characteristic of each amine in oil formulation. The contact angles were linked with the emulsion stability, which was described by the final emulsion volume. KCl particles were gradually made hydrophobic and the contact angle and emulsion stability increase until equilibrium with amine concentration. The obtained results suggest that water-in-oil (W/O) emulsions are produced at the equilibrium, while oil-in-water (O/W) emulsions are mostly unstable. The emulsion stability was experimentally found to depend on temperature and additional mixing time; the former lead to the coalescence phenomena, while the latter caused the phase inversion from O/W to W/O emulsions. This project confirms that the phase inversion technique could constitute a quick and reliable lab testing methodology to screen various amines in oil formulations. === Applied Science, Faculty of === Mining Engineering, Keevil Institute of === Graduate