Microfluidic Solvent Extraction of Metal Ions and Complexes from Leach Solutions Containing Nanoparticles

Abstract

Solvent extraction is often hindered by the presence of particles and surfactants that increase the stability of emulsion phases, i.e., crud, thus preventing full recovery of the organic phase and the valuable metal species. It is shown that bypassing the formation of a particle-stabilized crud using a stream-based microfluidic extraction approach has great potential for handling these more challenging and industry-relevant systems provided sufficient throughputs can be realized. Metal ions and complexes are extracted from copper oxide and chromite leach solutions at high efficiencies and extraction rates within the confinement of a microchannel and in the presence of silica nanoparticles. These findings and their implications for process intensification are discussed.

Microfluidic Solvent Extraction of Metal Ions from Industrial Grade Leach Solutions: Extraction Performance and Channel Aging

“…The results for all CuSO 4 leach solutions (model or real, with or without particles) were indistinguishable, with equilibrium reached after contact times of less than 1 min. The complete set of data is presented elsewhere [6]. The results for copper extraction (microSX) shown in Figure 1 (a) are representative of the collection of data.…”

“…The original ore is a natural, heterogeneous material, and the leaching process can liberate other materials that are present. Thus, other than metal ions, mineral leach solutions very often contain fine silica (and other) particles and small amounts of organic material, which are known to slow down or completely arrest phase separation (as discussed above) [6,7]. Poor flow stability and phase separation in microfluidic solvent extractions might be anticipated for such complex solutions and are addressed in the present study.…”

“…Liquid-liquid and liquid-gas extractions can be carried out very efficiently in a microfluidic chip due to the high surface-tovolume ratio [2][3][4][5][6][7][8][9]. Fluids may be contacted as laminar streams [2,[5][6][7][8] or via the formation of droplets [3,4,9], which are maintained for a period of time (contact time) and then phase separated.…”

“…Fluids may be contacted as laminar streams [2,[5][6][7][8] or via the formation of droplets [3,4,9], which are maintained for a period of time (contact time) and then phase separated. The latter may be achieved through several mechanisms, including branching laminar streams at a channel junction [2,[5][6][7][8] or, for droplet dispersions, via spontaneous [10] or triggered [4] coalescence. Solutions containing particles or surfactants, however, pose significant problems for phase separation via coalescence due to the increased emulsion stability, regardless of whether conventional or micro-solvent extraction is used.…”

Solvent extraction of Nd(III) in a Y type microchannel with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester

“…In particular, they have the following advantages [11][12][13][14][15]: (1) an effective extraction in a short time due to high surface area to volume ratio; (2) simple operation and an environment friendly system; and (3) fast and direct amplification via "numbering-up" parallel processing without scale-up effect. Many literatures indicate that solvent extraction can be carried out very efficiently in a microfluidic chip, due to the high surface-to-volume ratio [16][17][18][19].…”