Rare earth element enrichment using membrane based solvent extraction

Abstract

Abstract. The chemical, catalytic, electrical, magnetic, and optical properties of rare earth elements are required in broad applications. Rare earth elements have similar physical and chemical properties thus it is difficult to separate one from each other. Rare earth element is relatively abundant in earth's crust but rarely occur in high concentrated deposits. Traditionally, ion-exchange and solvent extraction techniques have been developed to separate and purify single rare earth solutions or compounds. Recently, membrane starts to gain attention for rare earth separation by combining membrane and proven technologies such as solvent extraction. Membrane-based process offers selective, reliable, energy efficient and easy to scale up separation. During membrane-based separation process, one phase passes through membrane pores while the other phase is rejected. There is no direct mixing of two phases thus the solvent loss is very low. Membrane can also lower solvent physical properties requirement (viscosity, density) and backmixing, eliminate flooding phenomenon and provide large interfacial area for mass transfer. This paper will summarize research efforts in developing membrane technology for rare earth element separation. Special attention will be given to solvent extraction related process as the commonly used method for rare earth element separation. Furthermore, membrane configuration and its potentials will also be discussed.

Recent advances in waste lube oils processing technologies

“…Membrane-based processes have been widely used in various fields, such as water treatments [79][80][81][82][83][84][85][86][87], wastewater treatment [88,89], gas separation [90,91], energy conversion [92], medical and chemical processing [93][94][95][96][97], food processing and biotechnology [98][99][100][101][102], and so on, competing with conventional processes [81][82][83][103][104][105][106][107]. The rapid growth in development and application of membrane technologies is due to their interesting features.…”

The Latest Achievements of Liquid Membranes for Rare Earth Elements Recovery from Aqueous Solutions—A Mini Review

“…In recent years, various membrane techniques have been used to remove REEs from different materials (including rare earth ores, waste, and wastewater) because they usually allow not only the selective separation of metal ions but are also reliable, energy-saving, and easy to scale [16]. In general, membranes are barriers separating two different phases, which allows for the selective separation of the mixture of chemical compounds, bypassing some substances and retaining others.…”

“…In general, membranes are barriers separating two different phases, which allows for the selective separation of the mixture of chemical compounds, bypassing some substances and retaining others. They can be categorized based on criteria such as, inter alia, origin (e.g., synthetic, natural), morphology (e.g., porous, non-porous), or driving force (e.g., microfiltration, reverse osmosis) [16][17][18]. One of the types of membranes successfully used to remove or recover different metal ions from various solutions (sources) is a liquid membrane (LM), which enables the solvent extraction and stripping processes in a single step.…”

Graphene Oxide-Based Nanofiltration for Hg Removal from Wastewater: A Mini Review

“…One of the membrane technology techniques considered to separate ions is nanostructured membrane technology. Graphene is one of the materials that has a nanostructure can be used as a thin and flexible membrane sheet with high chemical stability and high mechanical strength [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Monolayer graphene membranes are accepted to be able to remove metal ions very effectively and efficient for wastewater due to their nanopores [ 31 , 32 ].…”