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in Wiley Online Library (wileyonlinelibrary.com) Microscopic mixing using magnetic nanoparticles (MNP) unveils exciting ramifications for process intensification in chemical engineering. This study explores the use of oil-in-water MNP emulsions to achieve mixing in a nonmagnetic continuous phase tantamount to that occurring in equivalent dilute ferrofluid suspensions. To assess the technique, measurements of the torque exerted by ferrofluid emulsions and suspensions of equal magnetic content were performed in rotating, oscillating, and static magnetic fields. Results show that momentum transfer is fairly alike in amplitude and proportionality for the two types of systems of equal magnetic content under the three types of magnetic fields. This implies that momentum of spinning nanoparticles in the emulsions is transferable to the oil droplets containing them which, in return is then transferred to surrounding nonmagnetic liquid. The magnitude of the resulting mixing allows for the foresight of a versatile MNP mixing technology completely separated from the target phase being mixed.

Reliable measurements of hydrophobicity of minerals and ores are important to the study of the separation performance of a froth flotation process. However, surface heterogeneity, which is inexorably linked to actual industrial ores, has always been a challenging factor to characterize with currently existing measurement techniques. In this study, a new apparatus of surface flotation that provides surface floatability and wettability evaluation requiring parsimonious needs in sample consumption is presented. It consists of a continuous‐flow macroscopically flat‐interface flotation cell for the selective separation at a moving liquid‐gas interface between hydrophobic mineral and hydrophilic gangue from scanty mineral samples. To prove the concept, comparative experiments were conducted with a mineral matrix composed of graphite and quartz using the new surface flotation apparatus, a micro‐flotation cell, and a Denver cell. The results obtained from the surface flotation cell indicate that its separation efficiency and its reproducibility are better than the two standard laboratory separation techniques. Use of this new technique provides more and better information related to the wettability of mineral/ore surfaces while requiring as low as 3 g of mineral samples.

In the presence of Cu ions, a packed bed electrochemical reactor (PBER) was employed to deliberately avoid or induce galvanic coupling between pyrite and Cu-activated sphalerite. The effect of galvanic interaction on Cu ions uptake and xanthate adsorption were investigated. Solution chemistry and surface chemistry studies (ethylenediaminetetraacetic acid extraction and time of flight secondary ion mass spectrometry) have observed that when sphalerite and pyrite were galvanically coupled, Cu ions migrated from the pyrite surface to the surface of the sphalerite. Along with the marked decrease in the adsorption of Cu ions on pyrite, xanthate adsorption on the minerals also dramatically dropped. The pseudo-adsorption rate constant for the minerals in the mixed mode is only 0.0583 s -1 , much less than that in the decoupled mode, which is 0.1368 s -1 . This testing program shows that the galvanic coupling of minerals contributes to more copper transfer and Cu ions preferentially adsorbed by sphalerite rather than pyrite. This affects the pyrite surface and causes it to become xanthate unflavoured.