Separation Of Rare Metals Research Articles

Rare metals recycling from spent NCM cathode materials and simultaneous dehydrofluorination of polyvinylidene fluoride (PVDF) in subcritical water

Several studies have examined the recovery of lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn) from used lithium-ion batteries (LIBs). However, the environmentally friendly and cost-effective leaching and efficient separation of rare metals from the active cathode material of LIBs remains a challenge. In this study, we present a novel route for the extraction of high-value metals from the NCM cathode material of spent LIBs using subcritical water-containing polyvinylidene fluoride (PVDF). The experimental parameters such as reaction temperature, time, liquid–solid and mass ratios, were carefully investigated. The raw cathode material and the solid residues before and after leaching were characterized using ICP-OES, XRD, FT-IR and SEM-EDS analyses. Results showed that the maximum extraction efficiencies of Li, Ni, Co, and Mn of (98.69, 98.24, 97.52, and 99.04) %, respectively, were achieved under the optimized conditions of 350 °C, 2 h, 1:3 mass ratio, and 60:1 mL/g liquid–solid ratio. Meanwhile, the experimental results of leaching kinetics revealed that the reaction in the system was controlled by the surface chemical reaction model with the linear fitting degree of (R2 = 0.97–0.99) and the calculated activation energies of 63.72 kJ/mol (for Li), 73.55 kJ/mol (for Ni), 74.99 kJ/mol (for Co), and 71.88 kJ/mol (for Mn). The overall findings of this research concluded that the PVDF-assisted subcritical water extraction process is a beneficial and a promising alternative to other existing methods.

Recovery and Separation of Rare Metals during the Processing of Eudialyte Concentrate with New Reagents of a Series of Phosphoryl Ketones

Recovery and Separation of Rare Metals during the Processing of Eudialyte Concentrate with New Reagents of a Series of Phosphoryl Ketones

The role of citric acid in the flotation separation of rare earth from the silicates

The Nechalacho project is the most advanced large heavy rare earth elements (HREE) project outside of China. Open circuit and locked cycle flotation tests along with pilot plant testing of rare earth elements (REE) concentration from the host rocks are accomplished with collectors of alkyl phosphates and the modifier of citric acid. In this study, the function of citric acid in the separation of rare metals against silicates is investigated by a combination of micro-flotation tests and time of flight secondary ion mass spectrometry (ToF-SIMS) surface chemical analysis. It was observed that there was little effect of citric acid on the REE recovery in the micro-flotation tests conditioned with de-ionized water (DIW). To evaluate the flotation response with excess secondary ions in the pulp, micro-flotation tests were performed to look at changes in recovery as a result of adding Al ions and the subsequent presence of citric acid. The results from three micro-flotation tests (DIW, DIW with the addition of 100mg/L Al and DIW+100mg/L Al and 500g/t citric acid) revealed that the addition of Al ions led to a decrease of REE grade, a lower REE minerals recovery and/or an unexpected promotion of silicates to the concentrate. Citric acid reduced the negative effect generated by the Al ions in the flotation, which was shown by an improvement in REE grade. ToF-SIMS surface analysis of undifferentiated grains from the tests with and without citric acid revealed that grains reporting to the concentrate are doing so in response to collector attachment in combination with having more secondary Al on their surface. Citric acid may partially form aqueous soluble metal–ligand complexes resulting in less Al ions on the grains surface, which were rejected to the tailings. Citric acid also may form chelation competing for adsorption on gangue minerals, resulting in a diminished effectiveness of the activation site.

Separation of thorium ions from wolframite and scandium concentrates using graphene oxide.

The separation of rare metals from the ores and commercially available compounds is an important issue due to the need of their high purity in advanced materials and devices. Important examples of two highly important elements that co-exist in the ores are scandium and thorium. Scandium containing ores and consequently also commercially available scandium compounds often contain traces of thorium which is very difficult to separate. We used graphene oxide for the selective sorption of thorium ions from scandium and thorium mixtures originating from the mined ores as well as from commercially available scandium salts. Our results showed that graphene oxide has an extreme affinity towards thorium ions. After the sorption process the graphene oxide contained over 20 wt% of thorium while the amount of scandium sorbed on GO was very low. This phenomenon of high sorption selectivity of graphene oxide can be applied in industry for the purification of various chemicals containing scandium and for separation of thorium containing mixtures. Alternatively, this methodology can be used for preconcentration of thorium from low-grade ores and its further use in the new generation of nuclear reactors.

ChemInform Abstract: The Preparation of Supported Ionic Liquids (SILs) and Their Application in Rare Metals Separation

AbstractReview: 58 refs.

The preparation of supported ionic liquids (SILs) and their application in rare metals separation

This review summarizes the preparation methods of support ionic liquids (SILs) and their applications in rare metals separation. The rare metals separation includes the recovery of high value metal ions and the removal of heavy metal ions from wastewater. SILs can be used as a kind of highly efficient multifunctional separation materials. The preparation methods of SILs include chemical immobilization technique in which ILs moieties are supported on solid supports via covalent bonds and physical immobilization techniques in which ILs are immobilized on solid supports via physical method such as simple impregnation, sol-gel method. According to the difference of solid supports, this review summarizes the application of polymer supported ionic liquids (P-SILs), silica based material supported ionic liquids (SM-SILs) and membrane supported ionic liquids (M-SILs) in rare metals separation. P-SILs and SM-SILs prepared by chemical method with N-methylimidazolium group can be used as highly efficient anion exchangers with high thermal stability and good chemical stability for adsorption of Cr(VI), Re(VII), Ce(IV). P-SILs prepared via simple impregnation afforded IL functionalized solvent impregnated resins (SIRs) which showed high separation efficiency and selectivity in the separation of rare earths(III) (REs(III)). SM-SILs prepared via sol-gel method with IL doped in the support as porogens or extractant show high removal efficiencies and excellent stability for the separation of RE(III), Cr(III) and Cr(VI). M-SILs with IL as plasticizer or carrier show improved stability, high permeability coefficient and good selectivity for Cr(VI) transport. Different supports and different supporting methods were sufficiently compared. Based on the different practical application, different forms of SILs can be prepared for separation of rare metals with high separation efficiency and selectivity.

Separation of rare metals in plasma chemical pyrolysis of petroleum residues

A method is proposed for separating industrial carbon with rare metals from pyrolysis gases obtained in plasma-chemical processing of hydropyrolysis residues from high-viscosity high-sulfur crude oil (HHC).

Separation of Rare Metals by Solvent Extraction Employing Reductive Stripping Technique

The Separation and purification of vanadium from V/Mo mixture and europium from Sm/Eu/Gd mixture by solvent extraction followed by chemical, electrochemical or photochemical reductive stripping, has been investigated. Vanadium (penta) was first extracted into organic phase along with molybdenum from their solution mixture, and the vanadium reduced either chemically by L-ascorbic acid, electrochemically using platinum electrode or photochemically using low pressure mercury or halogen lamp. The resulting vanadium(tetra) was then separated by selective stripping. In the case of mixed rare earths solution, Eu3+ was reduced to Eu2+ electrochemically using titanium plate electrode or photochemically using low or high pressure mercury lamp. The divalent europium thus obtained was then precipitated selectively to effect separation from samarium and gadolinium.