Primary Amine N1923 Research Articles

A sustainable separation strategy for recovering Sm/Co from SmCo magnets with fatty acid and primary amine

Acidic extractant is a kind of extractants commonly used in critical metal recovery industry, but the saponification wastewater generated during the saponification process inevitably causes environmental pollution. In order to develop a sustainable separation strategy for rare earth, the synergistic effect between lauric acid (LA) and primary amine N1923 (RNH2, with R = C19-C23) was investigated in this paper. The study revealed that the hydrogen bond between LA and RNH2 was helpful to realize the saponification of LA, thereby significantly improving the extraction and separation performance of LA. Unlike the quaternary ammonium or quaternary phosphonium in ionic liquid saponification studied in the previous study, RNH2 can independently combine hydrogen ions to achieve the deprotonation of LA without adding alkali or basic resin, which makes the extraction and separation process more environmentally friendly. Aiming at the recovery of samarium cobalt (SmCo) magnet, the separation of Sm and Co in chloride medium was systematically studied. When LA and RNH2 were combined in equal molar proportions to extract Sm, the extraction system demonstrated a high synergistic coefficient of 61.94, and separation coefficient of Sm and Co was remarkably high at 5326.2. It showed that the LA-RNH2 extraction system for recovering Sm and Co from actual SmCo magnets could achieve 93.19 % recovery of Co, 90.53 % recovery of Sm and 16,222 Sm/Co separation factor. The LA-RNH2 extraction system has shown potential applications in Sm/Co separation and waste SmCo magnet recovery processes. It also provides a novel strategy for the saponification of acidic extractant without alkali consumption and saponification wastewater discharge.

Controllable molecular orientation at the interface and coordination with second hydration-sphere to enhance separation of Pt(IV) and Pd(II) in hydrochloric acid solutions: Mass transfer based separation and molecular dynamics

In conventional liquid-liquid extraction, Pt(IV) and Pd(II) chloride complex anions PtCl62− and PdCl42− in concentrated hydrochloric acid cannot be separated using simple amine extractants according to the ion association mechanism based on the thermodynamic difference in the interaction of their inner sphere coordinated chloride ions with protonated amine. This study exhibits a novel strategy for enhancing the separation of PtCl62− and PdCl42− anions using thin-layer organic membrane-based laminar flow (TOMLF) extraction by controlling the acidified primary amine N1923 (A-N1923) molecular orientation on the surface of concentrated hydrochloric acid with a laminar shear flow. Experiments revealed that the separation selectivity is primarily determined by the interaction of A-N1923 molecules with the outer sphere-bound water molecules around PtCl62− and PdCl42− anions, and is easily controlled by regulating the A-N1923 molecular orientation on the surface of laminar flow. It is a new phenomenon that has not been previously documented. The evolution of A-N1923 molecular orientation and complexation sites induced by laminar shear flow would result in a controllable spatial geometry recognition, therefore promoting or inhibiting the separation of PtCl62− and PdCl42− anions in concentrated hydrochloric acid. This work is expected to provide new insight into the development of hydration-sphere coordination strategies based upon shear-switch laminar flow for controllable host-guest molecule recognition at a flowing liquid-liquid interface.

Selective recovery of thorium and uranium from leach solutions of rare earth concentrates in continuous solvent extraction mode with primary amine N1923

A continuous counter-current extraction for the selective recovery of thorium (Th) and uranium (U) from the Yen Phu (Vietnam) rare earth concentrate leach solutions was systematically studied. The primary amine N1923 was used as an extractant which was prepared in the isoparaffin IP-2028 diluent. Thorium and uranium were selectively recovered in a hydrometallurgical circuit established by continuous mixer-settler extraction, scrubbing, and back-extraction at the laboratory scale. The desired purity of Th and U can be achieved by managing the volume ratio of organic to aqueous phase (O/A ratio) in the corresponding steps. Highly pure Th and U were recovered from the pregnant back-extraction liquor and the raffinate, respectively, which have satisfactory properties for further processing of the subsequent nuclear materials.

Deep understanding of sustainable vanadium recovery from chrome vanadium slag: Promotive action of competitive chromium species for vanadium solvent extraction

The complete separation of vanadium (V) and chromium (Cr) from chrome vanadium slag is still challenging. Many studies focus on the activity of vanadium, while the effect of the other element chromium and their mutual interaction are ignored. Here, we found that proper concentration of chromium can promote the extraction efficiency of vanadium. The extraction of V and Cr with various mass ratios ranging from 8:1–4:3 at different initial pH values using primary amine N1923 were studied. The extraction efficiency of V reached nearly 100%, while none of Cr was extracted when the mass ratio of Cr and V is 0.5 under proper pH. Through the dynamic monitoring of species evolutions during extraction, the transformation of the two metals and advantage extracted species were analyzed. Cr would transfer H+ for the combination of V3O93-/V4O124-, providing a great contribution to the continuous extraction of V. The real leachate was applied and 99.9% vanadium pentoxide was produced at a scale of 50 L/h. This paper offers deep insights of the separation of similar metal elements, and guide sustainable vanadium recovery from hazardous waste.

A novel neutral-base coupling synergistic extraction system of Cyanex923 and primary amine N1923 for the recovery of cerium(IV) and fluorine from sulfuric acid medium

Cyanex923 (A) and primary amine N1923 (B) mixture was developed as a novel neutral-base coupling extraction system for the recovery of cerium(IV) (Ce(IV)) and fluorine (F−) from sulfuric acid (H2SO4) medium. This system demonstrated excellent synergistic effects for both Ce(IV) and F− extraction. In Ce(IV) solution, the maximal synergistic coefficient (Rmax) for Ce(IV) was 2.93 at the Cyanex923 mole fraction (X) of 0.6. In Ce(IV)-F− solution, the presence of F− enhanced the synergistic extraction of Ce(IV) with the Rmax-Ce(IV) of 4.39 at XCyanex923 = 0.6, meanwhile the synergistic coefficient for F− (Rmax-F−) reached 4.33. The synergistic extraction mechanisms were systematically studied through multiple techniques including stoichiometry analysis, FT-IR and NMR characterizations. Equilibrium structures of extracted complexes were determined as Ce(SO4)2∙(A)1.5(B) and CeF(SO4)1.5∙(A)(B). Thermodynamic investigations revealed that the synergistic extraction processes were spontaneous. Specifically, the extraction process for Ce(IV) was endothermic and entropy driven, while the extraction process for Ce(IV)-F− was exothermic and enthalpy driven. The extracted Ce(IV) and F− can be almost stripped completely using HNO3 with additive H2O2, and CeF3 particles were obtained by reductive stripping from Ce(IV)-F− loaded organic phase as confirmed by XRD, SEM and DLS. The Cyanex923-N1923 system achieved comprehensive recovery of Ce(IV) and F− from the Bayan Obo mixed RE H2SO4 liquor and this excellent synergistic extraction performance suggests its high practical application potential.

Extraction and separation of W and rare earth from H2SO4-H3PO4 mixed acid leaching liquor of scheelite by primary amine N1923

Tungsten and rare earth (La) in scheelite can be leached effectively using H2SO4-H3PO4 mixed acid leaching liquor, which contains W, La, and high concentrations of sulfuric and phosphoric acids. It is important to recover W and La from the leaching liquor to efficiently use scheelite. In this study, N1923 extraction and a two-step stripping process were developed to efficiently extract and separate W and La from the leaching liquor. First, W and La were directly extracted using N1923 from the leaching liquor (100 g/L sulfuric acid and phosphoric acid). Under the optimal conditions of N1923 (30% v/v), isooctanol (10% v/v), sulfonated kerosene (60% v/v, O/A (organic/aqueous ratio) 1:1, temperature 25 °C, and contact time 10 min), 99.9% W, and 96.5% La were extracted. High concentrations of sulfuric acid and phosphoric acid were not beneficial for this extraction process. Next, La was separated from the loaded organic phase by stripping using an HCl solution. Under the optimum conditions (HCl 2.5 mol/L, stripping time 20 min, O/A 1:1, and 40 °C) 89.7% La and almost no W were stripped after single-stage stripping. After three cross-current stripping stages, the total La and WO3 stripping reached 99.0% and approximately 0.1%, respectively. La was successfully separated from W. Finally, the remaining W was stripped using an ammonia solution. The amount of WO3 stripped exceeded 99% under the optimum ammonia concentration of 4.0 mol/L, stripping temperature of 40 °C, stripping time of 10 min, and organic/aqueous ratio of 1:1. W and La were extracted and separated efficiently from the H2SO4-H3PO4 mixed acid leaching liquor by N1923 and two-step stripping, respectively.

Recovery of thorium and rare earths from leachate of ion-absorbed rare earth radioactive residues with N1923 and Cyanex® 572

Ion-absorbed rare earth ores radioactive residues (IREORR) are a class of waste residue from the production of rare earth elements (REEs). Because of its radioactive dose, IREORR are usually stored in waste warehouses. IREORR are difficult to be disposed of. However, it contains relatively high concentrations of REEs, which can be considered as a valuable secondary resource. In this paper, a novel process is developed for the separation of thorium (Th) and recovery of REEs from IREORR hydrochloric acid leachate with primary amine N1923 and Cyanex® 572, respectively. The effects of sulfate concentration, extractant concentration and pH on N1923 extraction in hydrochloric acid solution were investigated in detail. The results show that the extraction capacity of N1923 can be improved by adding sulfate to the solution and increasing the concentration of N1923. Acidity has little effect on the extraction of Th when pH is higher than 1. As for the stripping, REEs are more easily stripped from loaded organic phase than Th, and nitric acid is a better stripping agent than hydrochloric acid. Combined with the extraction of Cyanex® 572 for REEs, a fractional extraction experiment for separating Th and enriching of REEs was performed. The yield of Th is higher than 99.9% and the concentration of REEs is enriched to 183.84 g/L.

Recovery of scandium from spent sulfuric acid solution in titanium dioxide production using synergistic solvent extraction with D2EHPA and primary amine N1923

High-efficiency and good-selectivity extraction systems are very attractive in the solvent extraction process. A synergistic extraction of scandium (III) from a spent sulfuric acid solution of titanium dioxide production by using a mixture of bis-2-ethylhexyl phosphoric acid (D2EHPA, P204) and primary amine (N1923) has been proposed in this study. The effect of the molar fraction of N1923 in the mixed extractants on the extraction of scandium was studied and the synergistic enhancement coefficient R was calculated. The maximum synergistic coefficient was found to be 12.50 when the H2SO4 concentration was 0.5 mol·L−1 and the molar fraction of N1923 was 0.5. The synergistic extraction mechanism was also discussed. Appropriately 90% scandium could be stripped from the loaded organic phase in the synergistic extraction system when the nitric acid was 6 mol.L−1. The result of FT-IR spectra well verified the conclusion that the synergistic effect owed to the formation of hydrogen bond NH+···OP, causing a much easier dissociation of proton H of P204. Finally, after three-stage counter-current extraction and stripping, Sc2O5 product with a high purity of 90% was obtained from spent sulfuric acid solution by precipitation and calcination.

Sustainable Extraction and Complete Separation of Tungsten from Ammonium Molybdate Solution by Primary Amine N1923

Complete separation of tungsten from molybdenum has long been a technical bottleneck in the metallurgy of molybdenum because no theoretical basis exists for the complexation and extraction mechanis...

Extraction of thorium using primary amine N1923 levextrel resin by a micro-column

The extraction behavior of thorium from Baotou iron ore with primary amine N1923 levextrel resins by a micro-column was investigated under the decompression technology. Thorium was adsorbed on the micro-column conditioned by 3 mol L−1 HCl solution before use. The washing liquor of 0.5 mol L−1 H2SO4–0.1 mol L−1 H3PO4 solution was used to wash impurity elements and the solution of 3 mol L−1 HCl was used as the eluent for thorium. The method was applied to analyze thorium in the Baotou iron ore sample. The relative standard deviations of thorium in R-715 standard sample, Baotou main ore standard sample and Baotou west ore were of 0.49%, 1.63%, 1.16%, respectively. The accuracy of the method was satisfactory.

Separation and Extraction of Scandium and Titanium from a Refractory Anatase Lixivium by Solvent Extraction with D2EHPA and Primary Amine N1923

Separation and Extraction of Scandium and Titanium from a Refractory Anatase Lixivium by Solvent Extraction with D2EHPA and Primary Amine N1923

Kinetics of V(V) extraction in V(V)-SO42− (Na+, H+)-primary amine N1923-sulfonated kerosene system using single drop technique

The kinetics of V(V) extraction from acidic sulfate medium by primary amine N1923(RNH2) dissolved in sulfonated kerosene has been investigated using a falling single drop technique. The time of drop formation and coalescence was determined and considered for calculating the V(V) transfer flux. The effects of aqueous pH, V(V) concentration and RNH2 concentration on the revised V(V)-transfer flux(F′) have been investigated with aim of obtaining the reaction orders for extraction rate. Activation energies (Ea) of extracted reaction for the aqueous pH of 2.0, 3.0 and 4.0 under the conditions of V(V) concentration of 0.24 mol/L, RNH2 concentration of 0.24 mol/L, temperature of 298 ± 0.5 K and an atmospheric pressure, were −8.04, −9.57 and −12.45 kJ/mol, respectively. The ΔH± for reactions under various operating conditions were also calculated according to the intercept of log(F′h/kT) versus (1/T) plots. The details studies on the kinetics of V(V) extraction from simulated industrial aqueous solution are significant to optimize its separation technology.

Separation of Tungsten from Phosphorus-Containing Molybdate Solution Using Solvent Extraction with Primary Amine N1923

A solvent extraction process for separation of tungsten from phosphorus-containing molybdate solution was developed using acidified primary amine N1923 as extractant. Most tungsten combines with phosphorus to form phosphorus-containing polymeric ions over a proper pH range, while the dominant form of molybdenum is still monomeric ions (MoO42−). The former can be preferentially extracted by acidified N1923. The initial pH, extractant concentration, 2-octanol concentration, and temperature were optimized. By employing an initial pH of 7.5, 15% by volume N1923, 5% by volume 2-octanol, T = 20°C, and O:A ratio of 1:1, 97.0% tungsten was extracted in a single stage, while limiting molybdenum coextraction to 12.5%. The concentration of WO3 in the raffinate was reduced to 0.28 g/L after two-stage continuous countercurrent extraction.

Modeling of liquid–liquid extraction of vanadium with primary amine N1923 in H2SO4 medium

This paper deals with a systematic thermodynamic study on the liquid–liquid extraction of vanadium from aqueous solution (0.001–0.1 mol/kg) using primary amine N1923 (0.004–0.3 mol/kg). Suitable and practical thermodynamic models (Pitzer–Pitzer and Pitzer–Margules) were improved and verified for the first time. Firstly, the Pitzer parameters were correlated based on solid–liquid equilibrium data, and then employed as the initial values in regression progress. Finally, all the interaction parameters (βaq0, βaq1, βRV,RVorg, βR,RVorg, βR,Rorg, ARV,Rorg, Atol,RVorg and Atol,Rorg) were regressed. Liquid–liquid equilibrium data were predicted using those parameters and compared to the experimental results, which confirmed the reliability and suitability of these models for the present system. Furthermore, these models provided excellent predictions of the effect of the initial amine molality and pH value on the extraction, showing great promise for industrial applications.

Three-liquid-phase extraction and separation of V(V) and Cr(VI) from acidic leach solutions of high-chromium vanadium–titanium magnetite

Abstract A new method by liquid–liquid–liquid three phase system, consisting of acidified primary amine N1923 (abbreviated as A-N1923), poly(ethylene glycol) (PEG) and (NH4)2SO4 aqueous solution, was suggested for the separation and simultaneous extraction of V(V) and Cr(VI) from the acidic leach solutions of high-chromium vanadium–titanium magnetite. Experimental results indicated that V(V) and Cr(VI) could be selectively enriched into the A-N1923 organic top phase and PEG-rich middle phase, respectively, while Al(III) and other co-existing impurity ions, such as Si(IV), Fe(III), Ti(IV), Mg(II) and Ca(II) in acidic leach solutions, could be enriched in the (NH4)2SO4 bottom aqueous phase. During the process for extraction and separation of V(V) and Cr(VI), almost all of impurity ions could be removed. The separation factors between V(V) and Cr(VI) could reach 630 and 908, respectively in the organic top phase and PEG middle phase, and yields of recovered V(V) and Cr(VI) in the top phase and middle phase respectively were all above 90%. Various effects including aqueous pH, A-N1923 concentration, PEG added amount and (NH4)2SO4 concentration on three-phase partitioning of V(V) and Cr(VI) were discussed. It was found that the partition of Cr(VI) into the PEG-rich middle phase was driven by hydrophobic interaction, while extraction of V(V) by A-N1923 resulted of anion exchange between NO3− and H2V10O284 −. Stripping of V(V) and Cr(VI) from the top organic phase and the middle PEG-rich phase were achieved by mixing respectively with NaNO3 aqueous solutions and NaOH-(NH4)2SO4 solutions. The present work highlights a new approach for the extraction and purification of V and Cr from the complex multi-metal co-existing acidic leach solutions of high-chromium vanadium–titanium magnetite.

Separation of tungsten from molybdate using solvent extraction with primary amine N1923

The separation of tungsten and molybdenum from solutions containing high concentrations of W(VI) and Mo(VI) using solvent extraction with a primary amine extractant N1923 was studied. W(VI) was selectively extracted over Mo(VI) by acidified N1923 at an equilibrium pH of 7.0. The extractant acidification with HNO3 performed better than with H2SO4 or HCl. The separation factor of W(VI) over Mo(VI) (βWO3/Mo) was mainly affected by the concentration of WO3. The co-extracted Mo(VI) could be scrubbed using ammonia solutions. The concentration of WO3 decreased from 43.6g·L−1 in the feed solution to 5mg·L−1 in the raffinate by a process consisting of two-step extraction and scrubbing, resulting in the decrease in WO3/Mo mass ratio from 1.7 to less than 5×10−4. This could meet the requirement on the preparation of ammonium molybdate (MSA) with MSA-0 grade of Chinese standards. A new solvent extraction process was developed to completely separate W(VI) from molybdate.

Enrichment of Low Concentration Rare Earths from Leach Solutions of Ion-Adsorption Ores by Bubbling Organic Liquid Membrane Extraction Using N1923

A new bubbling organic liquid membrane extraction using primary amine N1923 at large aqueous-to-oil phase ratios was suggested to extract and enrich extremely low concentration rare earths from the acidic sulfate leach solutions of ion-absorbing type rare-earth ores. It was revealed that bubbling organic liquid membrane extraction was in fact an interfacial chemical reaction of organic extractant molecules absorbing at the surface of the organic liquid membrane supported by gas bubbles with the target metal ions in the aqueous solutions. Rare earths with a concentration about 100 mg/L can be extracted selectively and enriched efficiently into the organic extractant liquid membrane layer covered on the surface of dispersed gas bubbles. However, Al in leach solutions was not extractable and remained in the raffinates, due to a kinetic nonequilibrium separation behavior of rare earths and Al on the surface of the organic liquid membrane. It was the differences in reaction rate of rare earths and Al with prim...

Rapid selective extraction of V(V) from leaching solution using annular centrifugal contactors and stripping for NH4VO3

Abstract The efficient and rapid selective extraction of V(V) from leaching solution with sulfated primary amine N1923 was demonstrated. In the single-stage extraction using annular centrifugal contactor (ACC), the influence of the total flow and the speed rotor on extraction percentage of V(V) was investigated using central composite design (CCD), and the results of experimental conditions were analyzed by analysis of variance. The current concentrations of V(V) and Cr(VI) in leaching solution were 23.70g/L and 1.52g/L, respectively. 99.6% of vanadium was extracted and separated from the aqueous solution by employing four-stage countercurrent extraction with annular centrifugal contactors (ACCs). The total contact/resident time of the two phases was 4.8 min, and the separation factor of V(V) and Cr(VI) was 273.9. The two metals in leaching solution can be separated primarily, and then 23.61g/L V(V) and 0.72g/L Cr(VI) in loaded organic phase can be further separated by the stripping. The NH4VO3 with purity of 99.7% was obtained by two steps of separations and studied by the analyses of XRD, SEM and particle size distribution (PSD). The reactions of extraction and stripping in the separation processes were investigated in order to establish a firm conclusion.

Synergistic extraction of gold(I) from aurocyanide solution with the mixture of primary amine N1923 and bis(2-ethylhexyl) sulfoxide in supported liquid membrane

Utilization of supported liquid membrane (SLM) for the extraction of Au(I) from alkaline cyanide solution was investigated. The SLM consisted of a synergistic mixture of primary amine N1923 and bis(2-ethylhexyl) sulfoxide (BESO) in kerosene as carrier and a hydrophobic microporous polyvinylidene fluoride (PVDF) membrane as the solid support. The presence of both BESO and N1923 extractants in the liquid membrane induces an evident synergistic effect, allowing the latter to transfer Au(I) from the highly alkaline solution (pH>9.21). The fundamental parameters influencing the gold transport, such as stirring speed, composition of the liquid membrane, feed pH, NaOH concentration in stripping solution, and initial gold concentration in the feed solution were explored. The gold transport is almost quantitative after 7h under the optimum process conditions: a mixture of (0.50mol/L N1923 + 0.75mol/L BESO) in kerosene as membrane phase, stirring rate of 1000rpm in both phases, 5.0mg/L gold in 0.20mol/L NaCl solution with a pH of 9.60, and 0.10mol/L NaOH as stripping agent. The parameters defining the mass transfer model of Au(I) through the SLM are experimentally determined as: maximum permeability coefficient, P = 31.45 × 10−6m/s, the diffusion coefficient for [Au(CN)2−·RNH3+ ·2BESO] complex across the liquid membrane, Dorg = 1.42 × 10–12m2/s, and the thickness of the aqueous diffusion layer, daq = 2.07 × 10−5 m. Selectivity of this SLM system was evaluated by performing the permeation test of Au(CN)2- with other metal cyanide species in aqueous solution and it was found that the gold ions were preferred over other impurity ones. Finally, stability of this SLM system has also been examined on a continuous run mode and satisfactory stability was observed for five runs.

Separation of V from alkaline solution containing Cr using acidified primary amine N1923 with the addition of trisodium citrate

Abstract Extraction and separation of V(V) and Cr(VI) in the alkaline solution obtained from the Sub-molten Salt Method to treat the high chromium vanadium slags has been a thorny problem in the past decades. In this work, a new liquid-liquid solvent extraction strategy was proposed by using acidified primary amine N1923 (denoted as A-N1923) to separate V(V) from alkaline solution containing Cr(VI) and Al(III). It was indicated that co-extraction of Cr(VI) and Al(III) with V(V) can be avoided with the addition of trisodium citrate previously into the feed solutions. The influence from various factors, including the concentration of trisodium citrate, the initial aqueous pH value, concentration of A-N1923 in the organic phase, diluents in the organic phase, and the initial concentration ratio of V(V) to Cr(VI) in alkaline solutions, on the separation of V(V), Cr(VI) and Al(III) were investigated. The extraction loading capacity of V(V) in the organic phase could reach 6.67 g/L at 298 K. Al(III) in the organic phase can be stripped selectively using 0.18 mol/L trisodium citrate solution, and then V(V) can be recovered by 1.0 mol/L NaNO3 solutions. The regeneration and reusability of the organic phases after stripping were discussed. The present work highlights a novel approach to separate and recover V(V) from alkaline leaching solution containing Cr(VI) and Al(III), especially being applicable for those strongly alkaline solution produced by treating the high chromium vanadium slags using the Sub-molten Salt Method.