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 t...