Synergistic Solvent Extraction Research Articles

Synergistic solvent extraction system composed of bis(pyridin-2-ylmethyl) dodecan-1-amine and dinonylnaphthalene for enhanced selective extraction of nickel and cobalt

Simultaneous recovery of Ni and Co from Fe(III) and Al is a critical challenge in hydrometallurgical processes. Recognized solvent extraction systems often struggle with selectivity and effective performance in mixed metal ion environments. Herein, a new synergistic solvent extraction (SSX) system comprised of a novel pyridine analog, N,N-bis(pyridin-2-ylmethyl) dodecan-1-amine (BPMDA), and dinonylnaphthalene sulfonic acid (DNNSA) with tributyl phosphate as phase modifier is introduced. The SSX system demonstrates high extraction performance achieving >90% for Ni and >97% for Co in a single-stage extraction process, with high selectivity. Under optimal conditions, the selectivity sequence is observed as Co2+ (>97%) > Ni2+ (>90%) > Mn2+ (<20%) > Fe3+ (<10%) > Mg2+ (<5%) > Al3+ (<2%) > Ca2+ (<1%). Spectroscopic analysis evidences the preferential binding of BPMDA with Ni and Co in the presence of DNNSA, concurrently achieving a significant reduction in the co-extraction of Fe(III) and Al. The selective complexation of Ni and Co using the SSX system offers a highly efficient and selective approach for their extraction, with promising potential for applications in recovery-based processes.

Selective extraction of nickel from acid leach solution of spent lithium-ion batteries using synergistic solvent extraction system consisting of TFCA-4PC

Selective extraction of nickel from acid leach solution of spent lithium-ion batteries using synergistic solvent extraction system consisting of TFCA-4PC

Separation of trace amount of nickel from cobalt sulphate solutions using a synergistic solvent extraction system consisting of dinonylnaphthalene sulfonic acid (DNNSA) and decyl 4-picolinate (4PC)

The current methods for separation of nickel from cobalt sulphate solutions have drawbacks of long flowsheets, release of large volumes of wastewater and incomplete separation of two metals. A synergistic solvent extraction (SSX) system consisting of dinonylnaphthalene sulfonic acid (DNNSA) and decyl 4-picolinate (4PC) is proposed in this work to extract nickel from cobalt sulphate solutions selectively. The extraction of nickel reached 99.7% after five-stage counter current extraction with an A/O volume ratio of 1/6 at 30 °C, resulting in a large increase of Co/Ni mass ratio to 25,700 in raffinate from 56 in feed. The loaded organic phase can be easily stripped using a dilute H2SO4 solution. Application of this process in industry is expected to make an important impact on the production of high-purity cobalt sulphate solutions and to deliver economic benefits.

Lithium Separation and Up-concentration from Battery Recycling Effluent by Synergistic Solvent Extraction

Exponential growth in the electric vehicle (EV) market warrants a stable supply of certain materials including lithium (Li). Due to its criticality and environmental concern, Li recycling from spent batteries is justified. Although there are several industrially established schemes for end-of-life battery recycling, major drawbacks are still encountered regarding Li recovery. In most recycling schemes, Li stands to be the last element that is recovered. This causes major loss of Li during the process and high energy is consumed to recover it from the final effluent i.e. evaporation, rendering Li recovery economically unattractive. Evaporation is generally applied to up-concentrate Li in the effluent to attain the minimum concentration required to induce precipitation and crystallization in Li salt production. In this research, solvent extraction is being proposed as a low energy alternative in Li up-concentration and separation from recycling effluent. The synergistic effect between 2-thenoyl trifluoro acetone (HTTA) and trioctylphosphine oxide (TOPO) as extractants in kerosene as diluent has been tested in batch studies to increase Li concentration in the final solution. Optimal extraction conditions reported include HTTA/TOPO mol ratio 1, shaking speed 250 rpm, extraction time 10 min, aqueous/organic volume ratio 1 and pH 10.1 (Li extraction rate 55.6 %). The maximum loading capacity of organic phase for Li was 1.2 g/L and complete stripping of Li could be achieved using 0.5 M sulfuric acid. It was demonstrated that the solvent extraction scheme can increase Li concentration in the effluent from 0.23 g/L to 10.06 g/L, which is suitable concentration for Li salt production by further precipitation or crystallization.

Separation and Recovery of Copper and Nickel in the Leachate of a Waste IC Lead Frame through Synergistic Solvent Extraction Using a Binary Extractant Containing LIX984N and Cyanex302 Followed by Selective Stripping

The IC lead frame is an essential component in semiconductor packaging, primarily composed of a nickel (Ni)–copper (Cu) alloy in which Ni is electroplated onto a Cu substrate. In this study, synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302, followed by two-stage selective stripping using sulfuric acid (H2SO4) and nitric acid (HNO3) as the stripping agent, was employed to separate and recover Cu and Ni from the leachate of an IC lead frame. The results indicated that under the optimal conditions of synergistic solvent extraction with an extraction pH value of 1, an extractant concentration of 0.015 M LIX984N + 0.0375 M Cyanex302, an extraction aqueous/organic (A/O) ratio of 1:1, and an extraction time of 5 min, the extraction efficiencies for Cu and Ni were 99.8% and 1.17%, respectively. The distribution ratios were DCu 999 and DNi 0.012, resulting in a separation factor of 83,250. In addition, the separation factor was much higher than that of using individual extractant of LIX984N (6208.3) or Cyanex302 (22,185.2). Subsequently, under optimal first-stage stripping conditions, using 0.05 M H2SO4 at a stripping organic/aqueous (O/A) ratio of 1:1, and with a stripping time of 3 min, a stripping efficiency of 99.9% for Ni was achieved. Next, under optimal second-stage stripping conditions, using 5 M HNO3 at a stripping O/A ratio of 2:1, and with a striping time of 3 min, a stripping efficiency of 99.9% for Cu was achieved. Finally, sodium hydroxide (NaOH) was added to the respective stripping solutions to precipitate Ni and Cu ions, followed by calcination treatment for the precipitates to obtain NiO and CuO, respectively. The purity of the former was 99.74% and that of the latter was 99.82%. The results demonstrate that synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302 can almost entirely extract Cu in the leachate of an IC lead frame at a lower extraction pH and a lower extractant concentration, thus reducing the co-extraction of Ni. In addition, less co-extracted Ni in the organic phase can be selectively stripped using dilute H2SO4, thus reducing the co-stripping of Cu. Hence, the effective separation and recovery of Cu and Ni in IC lead frame leachate can be achieved, which contributes to improving the sustainability of natural resources.

Separation of rhodium from iridium through synergistic solvent extraction

There are currently few effective processes for the solvent extraction of rhodium from hydrochloric acid streams, and none that allow rhodium to be selectively extracted over iridium. Realizing this goal could allow rhodium to be recovered earlier in a typical platinum group metal (PGM) refining flowsheet and reduce the environmental impact of PGM refining. In this work, we show that a synergistic combination of a tert-alkyl primary amine LA and various inner-sphere ligands L can be used to recover rhodium via the complex [RhCl5L].HLA2. Although we show that rhodium is extracted by several extractant combinations, it is only readily stripped from the amine/amide synergistic mixture. As this extraction relies on the inner-sphere coordination of the amide to the metal, this process also demonstrates a route to obtain preferential extraction of rhodium over more inert iridium chloridometalates under industrially relevant conditions.

Research on treatment of oil-based drill cuttings based on ionic liquids synergistic solvent extraction

The method of solvent extraction has a good application prospect in the treatment of oil-based drill cuttings, but the existing extractants have the high potential safety hazards of a low flash point and volatility. Therefore, this article proposes to use an ionic liquid with improved safety and strong extraction capacity to treat oil-based drill cuttings through a collaborative solvent extraction method. The extraction effect of different extractants and different ionic liquid synergistic extractants were studied, respectively. The research results showed that [IM18, H2]Br ionic liquid has a good synergistic effect with n-butanol, and the extraction rate could reach 99.14%. The experimental conditions were that the mass ratio of [IM18, H2]Br to n-butanol was 1:10, extraction time was 40 min, and the mass ratio of drill cuttings to extractant was 1:3. Under these experimental conditions, the mixed extractants can be recycled 3 times. The closed flash point of extractants increased from 35 °C to 53 °C, and the boiling point of extractants decreased from 117 °C to 90–107.3 °C. Based on this, the mechanism of ionic liquids synergistic solvent extraction was discussed.

Synergistic Extraction of Ga(III) from Chloride Solution by Mixture of Cyanex 272 and Alamine 336

Aming to select a suitable system for the synergistic solvent extraction of Ga(III), solvent extraction (SX) experiments were carried out by using acidic organo-phosphorous extractants, namely P204, P507 and Cyanex 272, and their mixtures with neutral extractants (TBP, N503) or amine extractants (Alamine 336). Among the studied mixtures, a remarkable synergistic effect for Ga(III) extraction was resulted by the combination of Cyanex 272 and Alamine 336 and the maximal synergistic enhancement coefficient reached 3.11. Compared to the single Cyanex 272, higher equilibrium pH values were observed when mixture of Cyanex 272 and Alamine 336 was employed. The extraction of hydrogen ions by Alamine 336 during the reaction was considered to be responsible for the synergistic extraction, and thus the the extraction of Ga(III) by Cyanex 272 was promoted. Finally, the synergistic extraction stoichiometry of mixture of Cyanex 272 and Alamine 336 for Ga(III) was projected by slope analysis. Ga(OH)A2 was resulted to be the composition of extracted complexes.

Modeling of synergistic solvent extraction of Zr(IV) / HCl / TOA+Cyanex 921 system using statistical analysis and neural network

Multi-linear regression analysis (MLR), radial basis function (RBF) and multilayer perceptron (MLP) of artificial neural network (ANN) with five inputs (temperature, concentrations of HCl, TOA, Cyanex 921, Zr (IV) and percentage of extraction (%E)) as only output were employed for the construction of models. It was observed that ANN (RBF and MLP) performed better as compared to the MLR model. Based on the models proposed, the extraction of Zr(IV) could be predicted under variable experimental conditions of concentrations of HCl, TOA (Tri-n-octylamine), Cyanex 921 (Tri-n-octyl phosphineoxide), Zr(IV) and temperature. The nonlinear and complex relation between the percentage of extraction and operating variables have been determined using two and three layered feed forward neural network with back-propagation of error learning algorithm. Uncertainties in data have been determined in terms of statistical parameters such as root mean-squared error and R-squared values to check the efficiency of the model for prediction.

A new process to produce battery grade lithium carbonate from salt lake brines by purification, synergistic solvent extraction and carbon dioxide stripping

There are abundant lithium resources in China, and the demand for lithium salts is high. However, lithium resources of the sulfate salt lakes in Tibet, such as Baqiancuo Salt Lake, have not been effectively utilised. This study proposes a synergistic extraction system composed of LIX 54, TRPO, and surfactant ADD-1 for efficient lithium extraction from the brine and separation of impurities. The CO2 gas stripped lithium and produced high-purity lithium bicarbonate solution. Thermal decomposition produced lithium carbonate solid from the loaded strip solution. The comprehensive yield of lithium was higher than 95%, and the quality of the lithium carbonate product reached the battery chemical grade standard. This new process offers a new way for the utilisation of lithium resources in salt lakes.

The impact of acidic media on the synergistic solvent extraction of Sm and Lu by mixture of organophosphorus extractants

The impact of acidic media on the synergistic solvent extraction of Sm and Lu by mixture of organophosphorus extractants

Selective co-extraction of critical metals from deep ocean polymetallic nodule leachate and preparation of battery-grade Ni-Co-Mn solution

The high-efficient and economic recovery of Ni, Co, and Mn from the leaching solution is critical for the industrial application of deep-ocean polymetallic nodules processing. To reduce the reagent consumption and wastewater generation presented in the individual metal element separation processes, a synergistic solvent extraction (SSX) process that selectively co-extracted Ni, Co, and Mn by the mixed extractant of pyridine carboxylate ester and naphthalene sulfonic acid was developed. Furthermore, the unit operation optimization and the extraction mechanism were systematically investigated. Experimental results demonstrated that almost all the Ni and Co were selectively extracted and left the impurities such as Ca and Mg in the raffinate by the synergistic extraction under optimal conditions. Moreover, a quantitative extraction of Mn could be achieved by controlling the excess coefficient of the organic extractant. By the aid of FTIR, HRMS, and the slope method, the molecular formula of loaded organic was deduced as Ni(C16H25NO2)2(C28H43O3S)2·2H2O, in which structure nickel forms a stable six-coordination complex with the extractant and H2O. Then, a battery-grade Ni/Co/Mn sulfate solution (Ca less than 0.02 mg/L, Mg less than 0.05 mg/L) was produced by stripping with 0.75 mol/L H2SO4 solutions. In conclusion, recovery of Ni, Co, and Mn from the leaching solution of DPN by the co-extraction with the SSX system is a promising alternative for industrial application due to its highly efficient and economic efficiency brought by the short process, less reagent consumption and wastewater discharge.

Thenoyltrifluoroacetone: Preferable Molecule for Solvent Extraction of Metals—Ancient Twists to New Approaches

A review of the investigations devoted to the solvent extraction processes of metal ions with a chelating ligand thenoyltrifluoroacetone (HTTA) is presented herein. It seems that this molecule has been preferred in the field for more than half a century, and that it is used very often as an extractant for almost all metals. The main objective of the present review is also to provide an overview of the synergistic solvent extraction of lanthanoids, particularly with the use of a β-diketone−neutral mixture. Based on the previous published results in the open literature, the extraction efficiency has been examined in detail and discussed further mainly in terms of the corresponding equilibrium constants among other outlined, so-important parameters. Major conclusions on the role of ligating groups of extractants towards the mechanism, an improved extraction enhancement, and selectivity are additionally provided. The fact that ionic liquids (ILs) appear to be replacing volatile diluents in the field of the liquid–liquid extraction of metals, again with the participation of this β-diketone, is not surprising. As is well known, a very efficient and simple way to determine the stoichiometry of the extracted species in the organic phase is by the simple use of the slope analysis method; however, it is sometimes difficult to perform, either because it somehow requests good solubility of the ligand or because obtained slopes are quite often far from integer values in ILs.

Separation of rare earths in chloride media by synergistic solvent extraction with mixture of HEHAMP and CA12 and stripping with HCl

The synergistic extraction of rare earths (REs) from chloride media by a mixture of two extractants 2-ethylhexylaminomethyl phosphonic acid mono-2-ethylhexyl ester (HEHAMP, HA) and sec-octylphenoxy acetic acid (CA12, HB) was investigated. A remarkable positive synergistic effect was observed at the molar ratio of HEHAMP to CA12 being of 2:3. The extraction of REs was found to be a cation exchange process and the extracted species of Yb3+ was determined as YbCl2HAB. The separation factors (SF) of adjacent heavy REs, i.e. SFYb/Tm and SFLu/Yb, for the mixtures were 2.50 and 1.63, which were much higher than those of the sole HEHAMP and the sole CA12 system. In additional, the values of SFYb/Y and SFLu/Y were 7.17 and 11.14, respectively, which were higher than those of other reported synergistic systems and those of the sole HEHAEP or CA12 system, suggesting that the mixture of HEHAMP and CA12 is a potential synergistic extraction system for the separation of heavy REs and/or Y(III) from other heavy REs. A cascade extraction process for the separation of Y(III) from yttrium-enriched REs feed using the synergistic extraction system was developed, which are superior to sole CA12 system. The Y2O3 product with a purity of 99.4% was obtained by 8 extraction stages and 5 scrubbing stages.

Modelling of lithium extraction with TBP/P507–FeCl3 system from salt-lake brine

• A thermodynamic model was developed for Li extraction by TBP/P507/FeCl 3 system. • The model parameters were optimized by fitting the calculated to experimental data. • Extraction mechanism was clarified by modelling species distribution in organic. Recovery of lithium from Mg-rich salt-lake brines by solvent extraction has been widely studied for high Li + /Mg 2+ selectivity and Li + extraction efficiency. In a previous study, a ternary synergistic solvent extraction system consisting of tributyl phosphate (TBP), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507, denoted as HL) and FeCl 3 was developed, in which high Li + selectivity and efficient Li + stripping simply with water were realized. In this study, to further elucidate the extraction mechanism of the TBP/P507/FeCl 3 system and minimize the efforts on the process optimization for Li extraction from Mg-rich salt-lake brines with different component concentrations from different sources, a thermodynamic empirical model based on mass balances and equilibrium equations has been developed. The model parameters were optimized by fitting the calculated data to experimental results. By calculating the distribution of species in the organic phase with the model, it was found that Li + primarily existed in the form of [Li(TBP) 2 ][FeCl 4 ], followed by [Li(TBP)][FeCl 4 ]. When Li + was stripped with water, Fe 3+ mainly existed in the form of FeCl 2 L·HL·2TBP in the organic phase at low O/A ratios but converted to [H(TBP) 2 ][FeCl 4 ] at high O/A ratios. This thermodynamic model provides a guide for the design of practical process flow.

Extraction equilibrium of molybdenum(VI) and tungsten(VI) in aqueous solutions containing hydrogen peroxide by synergistic solvent extraction with TRPO and TBP

The separation of molybdenum from peroxotungstate solution with neutral phosphorus extractant such as trialkyl phosphine oxide (TRPO), tri-butyl phosphate (TBP) is often accompanied by extraction loss of tungsten, which greatly reduces the separation efficiency. To solve the above problems and optimize process, clarifying the reaction equilibrium of extraction is necessary. However, relevant research, especially the TRPO-TBP synergistic system, has not been reported. Here, based on the effect of extractant concentration and equilibrium pH on Mo and W extraction with three extraction systems (TRPO, TBP and TRPO-TBP), the Mo and W distribution equations in the two phases and the stoichiometry of chemical reactions were determined via slope analysis. The apparent extraction equilibrium constants and cumulative protonation constant of [Mo2O3(O2)4]2− were calculated by successive-approximation method. The order of the extraction equilibrium constants is as follows: logKMo-TRPO-H (5.8) > logKMo-TRPO-TBP-H (4.3) > logKMo-TRPO (3.8) > logKW-TRPO (3.7) > logKMo-TRPO-TBP (2.3). The synergistic mechanism of TBP for Mo and W extraction was revealed through Raman, FT-IR and 31P NMR spectroscopy, proposing a synergistic extraction compound TBP·[H2Mo2O3(O2)4·2H2O]·TRPO. The experimental results showed that keeping a higher equilibrium pH (2–2.5) can improve the separation efficiency of W and Mo, which verified the feasibility of optimization measure proposed based on equilibrium data. This study reveals the extraction mechanism of W and Mo in H+-H2O2/TRPO-TBP system, which can provide some reference for the optimization of separation process.

Synthesis of N-(2-ethylhexyl)-pyridine-4-carboxamide and its synergistic behaviors with dinonylnaphthalene sulfonic acid for the selective extraction of nickel and cobalt

The hydrometallurgical process for the recovery of nickel and cobalt requires a complex and expensive impurity removal process. Solvent extraction is widely used in industry for the separation, purification, and concentration of metals. However, current commercial extractants encounter some difficulties when cobalt and nickel are extracted from solutions containing a large amount of impurities such as manganese and calcium. There is an urgent need to develop new reagents for the selective extraction of Ni and Co. In this study, N-(2-ethylhexyl)-pyridine-4-carboxamide (NEHPCA) was synthesized, and the metal extraction capacity of its synergistic solvent extraction (SSX) system with dinonylnaphthalene sulfonic acid (DNNSA) and tributyl phosphate (TBP) modifier was examined. The experimental results show that the selectivity of the new SSX system has the order Cu > Ni > Co > Zn > Mn > Ca > Al ≈ Cr (III) ≈ Mg ≈ Fe (III), with excellent selectivity for nickel and cobalt. Using an organic phase composed of 0.7 M NEHPCA, 0.35 M DNNSA, and 0.2 M TBP under 1:1O/A operation, after three-stage theoretical extraction, more than 99% of nickel and cobalt can be recovered from a synthetic leaching solution of nickel laterite ore. Mechanistic studies showed that NEHPCA and water molecules participate in the internal coordination of metals, and DNNSA provided coordination anions to achieve charge balance, forming the Ni complex in this SSX system which existed most likely in the form of [Ni(NEHPCA)2(H2O)4](DNNS)2 in the organic phase.

Characterisation of Parameters Influencing the Phase Separation in Copper Solvent Extraction Systems Using Oxime-Type Extractants for the Field Operation

Solvent extraction (SX) is one of the most widely applied hydrometallurgical processes in copper production from oxide ore. As the high-grade ore deposits have been developed and depleted, now only low-grade ore deposits are being developed and are therefore facing obstacles of extreme processing conditions. This results in leaching gangue minerals and requires a more complicated solvent extraction system. Recently, synergistic solvent extraction has been introduced to separate copper from the leached solution with high impurities. However, operational obstacles arise due to the complicated solvent extraction process, including multi-stages of extraction, and using more than one extractant in a single solvent extraction system. The phase separation in solvent extraction is one of the major issues in field operation. A poor phase separation could affect the entire process and eventually cause production loss. Therefore, in this study, the phase separation behaviours were studied in consideration of the field operation. Major parameters considered in the study were the type of diluent, temperature, mixing speed, solution pH and Oxidation Reduction Potential (ORP), and addition of impurities (flocculant and colloidal silica). The phase separation behaviours in the continuous counter-current SX system using a pilot-scale mixer-settler in the above conditions was investigated.

Relative distribution enhancement: a new factor for the evaluation of synergistic solvent extraction

AbstractBACKGROUNDSolvent extraction is one of the most used processes worldwide for metal extraction at an industrial and laboratory scale. As a process that requires an external component, the selection of extractants is one of the most studied topics to find the most suitable ones for a particular case. The use of combined reagents, or so‐called synergistic extractants, is a branch of extraction studies that have proven better results than the use of solvents on their own. However, a comparison between synergistic extractants cannot be made with the currently reported factors. This paper provides a guide on clarifying the implications of the conventional synergistic factor, R, for the evaluation of the best extractant combinations. Moreover, a new indicator is proposed, named relative distribution enhancement factor, H, that will quantitatively measure the efficiency of the extraction and compare extraction enhancement among different experimental research.RESULTSFour references were selected to illustrate the use of the H factor in contrast with the R factor. The usefulness of the new enhancement factor H was demonstrated by evaluating the synergistic solvent extraction of rare earth elements. It was found that the use of R factors can mislead the selection of extractants ratio, and although synergism exists this does not imply an enhanced extraction.CONCLUSIONThe main finding of this work is that the newly developed H factor can easily detect extraction enhancement or diminishment and is not limited to the evaluation of two extractants. © 2021 Society of Chemical Industry (SCI).

Mechanism of Ferric Chloride Facilitating Efficient Lithium Extraction from Magnesium-Rich Brine with Tri-n-butyl Phosphate

The synergistic solvent extraction system comprising tri-n-butyl phosphate (TBP) and FeCl3 has been intensively studied for selective extraction of Li(I) from Mg(II)-rich brine. The extraction occurs via the formation of an ion-pair complex [Li(TBP)x][FeCl4] in which the negatively charged [FeCl4]− neutralizes the positively charged [Li(TBP)x]+. Counterintuitively, many other metal chlorides give much lower Li(I) extraction efficiency than FeCl3, although they can also form chlorometallate anions similar to [FeCl4]−. In this study, the capabilities of CuCl2, AlCl3, InCl3, and SnCl4 for Li(I) extraction with TBP were examined and compared with that of FeCl3, accompanied by speciation studies. It was found that (1) AlCl3 does not form [AlCl4]− while other metal chlorides (CuCl2, InCl3, FeCl3, and SnCl4) can form chlorometallate anions that could facilitate Li(I) extraction and (2) CuCl2, InCl3, and SnCl4 form neutral solvation complexes with TBP strongly, which hinders the formation of chlorometallate anions, but FeCl3 does not form neutral complexes with TBP. Concurrently being able to form [FeCl4]− and to avoid forming neutral complexes facilitates the efficient Li(I) extraction by FeCl3 with TBP.