An Experimental Study of Copper Extraction Characteristics in a T‐Junction Microchannel

Abstract

The extraction performance in a T-junction microchannel was investigated experimentally. CuSO 4 /H 2 SO 4 /AD-100/260 # solvent oil was chosen as the working system. The velocities of the aqueous and oil phases were varied from 0.0016 to 0.45 m s -1 , with Re M varying between 9 and 200. The experimental results show that the extraction process of copper in the microchannel is controlled by both reaction intrinsic kinetics and mass transfer, depending on the characteristics of the reaction and the fluid hydrodynamics. The maximum extraction efficiency is about 0.96, and the apparent overall volumetric mass transfer coefficient (k app a) is in the range of 0.02-0.2 s -1. In addition, the effects of the Cu 2+ concentration and the pH in the aqueous phase, the volumetric fraction of AD-100 in the oil phase, and the temperature on the extraction performance were investigated in detail. IntroductionLiquid-liquid extraction, which is also known as solvent extraction, is widely utilized in the process industries such as the petroleum, food, hydrometallurgy and chemical industries, and others. The extraction of copper is a representative process in the hydrometallurgy industry. The introduction of the LIX series extractants by General Mills Company was an exciting innovation for the copper mining industry, creating a great interest in the process of liquid-liquid extraction accompanying chemical reactions [1]. The extraction has been carried out in different contactors, such as the mixer-settler contactors, column contactors, etc. The mixer-settler [2] is free of backmixing between different stages and can be operated under nearly equilibrium conditions between the two phases. However, its recycling solvent and the energy consumption for mechanical stirring are very large. Besides, it requires large space for allocation. Extraction columns, such as sieve plate, pulsed, spray and rotating-disc columns, etc., have also been widely employed [3,4]. Although these contactors benefit from a simple structure, their utilization is limited due to extreme backmixing, which greatly reduces the extraction efficiency. Moreover, some other contactors are also exploited for extraction processes. Doungdeethaveeratana and Sohn [5] studied the extraction kinetics in a cylindrical vessel, and a high dispersion performance of the two immiscible liquid-liquid phases could be obtained by gas agitation so that better extraction efficiency was generated. Merchuk et al. [6] experimentally investigated copper extraction with LIX-64N by means of motionless mixing, and an approximate 92 % of equilibrium was achieved in the Koch static mixer. Nevertheless, some disadvantages still exist in these contactors, such as rigorous operating conditions, long extraction times, small overall volumetric mass transfer coefficients, etc.Microchemical engineering technology, as one of the most important process intensification modes, has been in the focus of industry and academia [7][8][9][10][11][12]. The extremely large surfaceto-volume ratio and the short tr...

Liquid–liquid two‐phase flow in ultrasonic microreactors: Cavitation, emulsification, and mass transfer enhancement

“…Liquid–liquid two‐phase process is widely encountered in a broad range of application areas, such as extraction, emulsification and reactions like nitration, acid catalyzed reaction, and so forth. In the aforementioned fields, mixing between the immiscible phases is usually the rate‐determining step due to large interfacial tension and mass‐transfer resistance at the interface .…”

Formation of liquid–liquid slug flow in a microfluidic T‐junction: Effects of fluid properties and leakage flow

“…Liquid–liquid multiphase transport in microchannels or porous media is an important topic in many areas, such as microchemical reactions, extraction, on‐chip microfluidic applications, oil recovery, and fuel cells . As interfacial forces dominate between immiscible phases at micro‐scale, it tends to minimize the total surface area to form spherical interface, which is the shape taken by an isolated droplet.…”

Intensified Eu(III) extraction using ionic liquids in small channels

“…The increased importance of interfacial phenomena, large interfacial areas and the ability to influence flow patterns make two-phase flows in small units particularly appealing. The benefits of microchannel operation have been clearly demonstrated for liquid-liquid extractions which often involve organic solvents with high hazard ratings (Kashid et al, 2005;Dessimoz et al, 2008;Kashid et al, 2010;Assmann et al, 2013;Xu et al, 2013;Yang et al, 2013).As extraction efficiencies depend on concentration gradients, interfacial area and residence times (Okubo et al, 2008), the exact flow pattern within the separation unit becomes important. Plug (or segmented) flow in particular, where one phase forms dispersed plugs with diameter larger than the channel size separated by continuous phase slugs, is a preferred pattern because the circulation patterns forming in the two phases and the thin films separating the plugs from the channel wall enhance mass transfer (Burns and Ramshaw, 2001;Kashid et al, 2005;Okubo et al, 2008;Jovanović et al, 2012).…”