Microfluidic solvent extraction of rare earth elements from a mixed oxide concentrate leach solution using Cyanex® 572

Abstract

Solvent extraction of rare earth elements (REEs) involves hundreds of individual extraction and phase separation cycles, fine adjustment of solution conditions, and individual stage and overall process times that are long. Therefore, we investigated microfluidic solvent extraction (microSX) of REEs from a leached mixed rare earth oxide (REO) mineral concentrate using a phosphorus-based cationic exchange extractant (Cyanex® 572). A Y-Y microchip was used, in which the aqueous and organic phases were contacted for up to 15 s with sub-second resolution. The extraction rate and selectivity for heavy REEs was determined for the prepared leach solution. Good selectivity for heavy REEs was observed using the microchip for leach solutions adjusted to pH 0.7. Extraction rates on the microchip were typically double that observed in conventional (bulk) solvent extractions, except for Lu and Yb, which were three-times faster. The faster extraction can be largely attributed to the higher surface-to-volume ratio achieved in our microfluidic experiments; double that observed for bulk extractions under the conditions employed.

Non-equilibrium solvent extraction in milliflow reactors: Precious and base metal separations with undiluted ionic liquids

“…[21] As such, this technology has been used in numerous solvent extraction studies on metal extractions and separations. [22][23][24][25][26] A popular flow pattern is slug flow (also referred to as plug flow or Taylor flow) where the immiscible phases form a segmented flow of sequential slugs and plugs. Internal vortices are formed inside the plugs due to a shear exerted by the continuous phase on the surface of the plug, leading to a very efficient mass transfer.…”

Effect of polyacrylamide on the process of removing impurities in the rare earth leachate

“…Chemical impurity removal method is commonly used to remove impurities due to its convenience and low cost (Zhang et al, 2016;Zhou et al, 2017;Hamza et al, 2019). Some research has been done in this area, and it has been found that ammonia, ammonium bicarbonate, and sodium sulfide can be used for the removal of impurities (Li and Chi, 1997;Kolar et al, 2016;Zhou et al, 2017). According to these studies, flocs, whose main component is aluminum hydroxide, will be formed in the impurity removal process (Luo et al, 2015).…”

Liquid–Liquid Extraction of Yttrium(III) Using 2-Ethylhexyl Phosphonic Acid Mono-2-ethylhexyl (EHEHPA) in a Microreactor: A Comparative Study

“…REEs (rare-earth elements) are known as the “treasure house of industrial materials” and fairly abundant in the earth’s crust, but the separation and purification of REEs are thorny issues since their physical and chemical properties are nearly identical. , To tackle this challenge, liquid–liquid solvent extraction is the commonly used technology in industrial production, and the increasing demand of security of industrial solvent extraction has become the central focus of scientific research . Currently, microreactors are widely studied in the field of liquid–liquid solvent extraction of rare-earth elements because extracting REEs in microreactors present many attractive properties: (1) Significant increase in boundary area and enhanced mass transfer; (2) low capital and operating costs, low energy consumption, and increase in efficiency of analytical techniques; − (3) significantly improved and safer working environment and avoidance of emulsification. , Although the inability to deal with fluid containing solids is the limitation of microreactors, advantages could be obtained by using microfluidic extraction technology in the REEs separation process …”