Search

The world's seas and oceans contain vast amounts of lithium, but the low concentration hereof renders solvent extraction impractical for its recovery. By contrast, seawater desalination brine, after treatment by nanofiltration, contains a roughly tenfold greater concentration of lithium than raw seawater. Hence, lithium can be effectively recovered from such streams using solvent extaction. Compared with other techniques to sequester lithium from dilute solutions, solvent extraction offers the advantages of simple operations, robust and well-established technology and high recovery yields. Thus, we propose a solvent-extraction based process to recover lithium from seawater desalination brine, treated by nanofiltration. The first step comprises the removal of magnesium and calcium using methyltrioctylammonium neodecanoate in p-cymene. This is followed by a lithium extraction step using the extractants Mextral 54–100 and Cyanex 923 in Shellsol D70 diluent. The lithium extract is then scrubbed with water and stripped with hydrochloric acid. Subsequently, residual alkaline earth metals are removed with sodium hydroxide in ethanol and finally lithium is precipitated using sodium carbonate. The solvent extraction, scrubbing and stripping steps were demonstrated on mini-pilot scale in continuous countercurrent mode (in mixer-settlers), while the precipitation steps were demonstrated in batch. The process was found to have an overall yield of 74%, affording a lithium carbonate product with a purity of 97 wt%.

UNLABELLED: A hydrometallurgical process is described for conversion of an aqueous solution of lithium chloride into an aqueous solution of lithium hydroxide via a chloride/hydroxide anion exchange reaction by solvent extraction. The organic phase comprises a quaternary ammonium chloride and a hydrophobic phenol in a diluent. The best results were observed for a mixture of the quaternary ammonium chloride Aliquat 336 and 2,6-di-tert-butylphenol (1:1 molar ratio) in the aliphatic diluent Shellsol D70. The solvent extraction process involves two steps. In the first step, the organic phase is contacted with an aqueous sodium hydroxide solution. The phenol is deprotonated, and a chloride ion is simultaneously transferred to the aqueous phase, leading to in situ formation of a quaternary ammonium phenolate in the organic phase. The organic phase, comprising the quaternary ammonium phenolate, is contacted in the second step with an aqueous lithium chloride solution. This contact converts the phenolate into the corresponding phenol by protonation with water extracted to the organic phase, followed by a transfer of hydroxide ions to the aqueous phase and chloride ions to the organic phase. As a result, the aqueous lithium chloride solution is transformed into a lithium hydroxide solution. The process has been demonstrated in continuous counter-current mode in mixer-settlers. Solid battery-grade lithium hydroxide monohydrate was obtained from the aqueous solution by crystallization or by antisolvent precipitation with isopropanol. The process consumes no chemicals other than sodium hydroxide. No waste is generated, with the exception of an aqueous sodium chloride solution. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40831-022-00629-2. ispartof: JOURNAL OF SUSTAINABLE METALLURGY vol:9 issue:1 pages:107-122 ispartof: location:Netherlands status: published

ispartof: SEPARATION AND PURIFICATION REVIEWS vol:52 issue:3 pages:242-261 status: accepted

A split-anion solvent extraction process was developed for the separation of precious metal ions Au(III), Pt(IV), Pd(II) and Rh(III) from aqueous chloride media using water-saturated ionic liquids. The metal extraction and stripping behavior of the chloride form [A336][Cl], bromide form [A336][Br] and the iodide form [A336][I] of the quaternary ammonium ionic liquid Aliquat 336 were compared. The three ionic liquids extracted Au(III), Pd(II) and Pt(IV) quantitatively in most cases, whereas the co-extraction of Rh(III) was strongly dependent on the acidity and the chloride concentration. Among the studied ionic liquids, [A336][I] achieved the highest separation factors between Pd(II)/Rh(III), Pt(IV)/Rh(III), and Au(III)/Rh(III) at 6 mol L−1 Cl−. Additionally, the selective stripping of the individual metal ions Pd(II), Au(III), and Pt(IV) was only possible from loaded [A336][I] using ammonia solution (NH4OH), sodium thiosulfate (Na2S2O3), and thiourea ((NH2)2CS), respectively. A closed-loop flow sheet was designed for the recovery of the precious metals from chloride media using split-anion extraction with [A336][I]. The integrated process was demonstrated to be suitable for the purification of Rh(III), Pt(IV) and Pd(II) from a complex metal feed such as the leachate of spent automotive catalysts. The ionic liquid-based split-anion extraction process is simple, selective and effective for the sustainable separation of the precious metals, using only one green extractant [A336][I], which can be regenerated for consecutive extraction-stripping cycles.

This study explores the feasibility of an integrated system comprising adsorption and crystallization in a pellet reactor to remove and recover lead from aquatic environment. The selective adsorption of Pb2+ over Ca2+ and Mg2+ was investigated using citric acid modified sugarcane bagasse (SCA) in batch and column systems. Selective separation of Pb2+ from the mixed solution was achieved at a molar ratio 3.22 C o , b a t c h C a + M g / C o , b a t c h P b

Extraction and separation of platinum group metals (PGMs) from secondary raw materials are usually carried out via hydrometallurgical processes. These processes use strongly oxidizing acidic soluti...

PLATInum group metals Recovery Using Secondary raw materials (PLATIRUS), a European Union (EU) Horizon 2020 project, aims to address the platinum group metal (pgm) supply security within Europe by developing novel and greener pgm recycling processes for autocatalysts, mining and electronic wastes. The initial focus was on laboratory-scale research into ionometallurgical leaching, microwave assisted leaching, solvometallurgical leaching, liquid separation, solid phase separation, electrodeposition, electrochemical process: gas-diffusion electrocrystallisation and selective chlorination. These technologies were evaluated against key performance indicators (KPIs) including recovery, environmental impact and process compatibility; with the highest scoring technologies combining to give the selected PLATIRUS flowsheet comprising microwave assisted leaching, non-conventional liquid-liquid extraction and gas-diffusion electrocrystallisation. Operating in cascade, the PLATIRUS flowsheet processed ~1.3 kg of spent milled autocatalyst and produced 1.2 g palladium, 0.8 g platinum and 0.1 g rhodium in nitrate form with a 92‐99% purity. The overall recoveries from feedstock to product were calculated as 46 ± 10%, 32 ± 8% and 27 ± 3% for palladium, platinum and rhodium respectively. The recycled pgm has been manufactured into autocatalysts for validation by end users. This paper aims to be a project overview, an in‐depth technical analysis into each technology is not included. It summarises the most promising technologies explored, the technology evaluation, operation of the selected technologies in cascade, the planned recycled pgm end user validation and the next steps required to ready the technologies for implementation and to further validate their potential. PLATIRUS project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement n° 730224.

A solvometallurgical process for the separation of indium(iii) and zinc(ii) from ethylene glycol solutions using the ionic liquid extractants Cyphos IL 101 and Aliquat 336 in an aromatic diluent has been investigated. The speciation of indium(iii) in the two immiscible organic phases was investigated by Raman spectroscopy, infrared spectroscopy, EXAFS and 115In NMR spectroscopy. At low LiCl concentrations in ethylene glycol, the bridging (InCl3)2(EG)3 or mononuclear (InCl3)(EG)2 complex is proposed. At higher lithium chloride concentrations, the first coordination sphere changes to two oxygen atoms from one bidentate ethylene glycol ligand and four chloride anions ([In(EG)Cl4]-). In the less polar phase, indium(iii) is present as a tetrahedral [InCl4]- complex independent of the LiCl concentration. After the number of theoretical stages had been determined using a McCabe-Thiele diagram for extraction by Cyphos IL 101, the extraction and scrubbing processes were performed in lab-scale mixer-settlers to test the feasibility of working in continuous mode. Indium(iii) was extracted quantitatively in four stages, with 19% co-extraction of zinc(ii). The co-extracted zinc(ii) was scrubbed selectively in six stages using an indium(iii) scrub solution. Indium(iii) was recovered from the loaded less polar organic phase as indium(iii) hydroxide (98.5%) by precipitation stripping with an aqueous NaOH solution. ispartof: RSC ADVANCES vol:10 issue:41 pages:24595-24612 ispartof: location:England status: published

A novel ionic liquid-in-water microemulsion (IL101/TX100/water) was developed for sustainable extraction and separation of precious metals (i.e., Au, Pd, and Pt) in acidic chloride media. Five-step protocol is composed of (i) mixing the feed solution containing precious metals with the ionic liquid based microemulsion; (ii) heating for phase splitting; (iii) phase separation; (iv) stripping; (v) regeneration. The aqueous microemulsion combines green properties of ionic liquid and advantages of microemulsion, and thus affords significant environmental benefits. Phase behaviour and structure of the microemulsion were determined by measuring the conductivity. Effect of various parameters was investigated for the complete extraction and selective recovery of highly pure precious metals (> 99.9% w/w). Based on anion exchange mechanism and micellar structure of the aqueous microemulsion phase, the extraction of Au(III), Pt(IV) and Pd(II) from chloride media characterized by 31P NMR spectroscopies was proposed as{(([P66614]+)m([A]n −)q(Cl−)m-nq)(TX-100)p} where [A]n − refers to the anionic metal species to be extracted, p denotes the average aggregation number of the TX-100 micelles, m the average number of [P66614]+ Cl− molecules in each (TX-100)p micelle and q the average number of [A]n − species extracted per micelle. Two-step stripping strategy was successfully adapted to treat the loaded ionic liquid-surfactant-rich (ILSR) phases with low aggressive media for the selective recovery of Au(III) with Na2S2O3 and Pd(II) and Pt(IV) with thiourea/HCl. The possible recirculation of regenerated ILSR phase without loss of performance was examined within five extraction-stripping cycles. Finally, a flow-sheet towards “zero-waste” concept was proposed for the complete extraction and selective recovery of individual precious metals using environmentally friendly aqueous microemulsion.

An effective solvent extraction-based method has been developed to recover individual platinum group metals (PGMs) (i.e. Pd, Pt and Rh) with high purity from acidic chloride media using phosphonium-based ionic liquid Cyphos IL 101 ([P66614]+Cl−) diluted in xylene used as a model of industrial diluents such as SOLVESSO 150. The system showed the selective co-extraction of Pd(II) and Pt(IV) from a feed solution containing 100 mg L−1 Pt(IV), 55 mg L−1 Pd(II), and 25 mg L−1 Rh(III) in HCl via an anion exchange mechanism, leaving Rh(III) in the raffinate. A McCabe–Thiele diagram demonstrated the quantitative extraction of Pd(II) and Pt(IV) with 0.6 g L−1 [P66614]+Cl− with two counter-current stages at an organic/aqueous (O/A) phase volume ratio of 3/2 at 298 K. The stoichiometry of complexes formed in the organic phases was determined using Job's method and further characterized by 1H, 13C, 31P NMR and UV-vis spectroscopy. More importantly, a two-step stripping strategy was successfully adapted to treat the loaded organic phases with low aggressive media NaSCN and thiourea/HCl for the selective recovery of Pt(IV) and Pd(II), respectively, with high purity >99.9% (w). Three counter-current stages are required for the quantitative stripping of Pt(IV) with 0.1 mol L−1 NaSCN at an O/A ratio of 3, whereas the total stripping of Pd(II) with 0.01 mol L−1 acidic thiourea requires only one stage at an O/A ratio of 5. A series of extraction-stripping processes of up to 5 cycles indicated a possible recirculation of regenerated solvent without loss of performance. Simulated experiments in continuous modes suggest that phosphonium-based ionic liquid such as Cyphos IL 101 can be advantageously used as extractant to recover individually Pd, Pt and Rh from acidic chloride feed solutions as those encountered in the PGM's recycling industry.

The present paper deals with the extractive separation and selective recovery of nickel and lithium from the sulfate leachate of cathode scrap generated during the manufacture of LIBs. The conditions for extraction, scrubbing and stripping of nickel from lithium were optimized with an aqueous feed containing Ni and Li using PC-88A. Over 99.6% nickel was extracted with PC-88A in two counter-current stages at O/A=1 and pH=6.5. Effective scrubbing Li from loaded organic was systematically studied with a dilute solution (). The McCabe-Thiele diagram suggests two counter-current scrubbing stages are required at O/A=2/3 to yield lithium-scrubbing efficiency of 99.6%. The proposed process showed advantages of simplicity, and high purity (99.9%) nickel sulfate recovery along with lithium to ensure the complete recycling of the waste from LIBs manufacturing process.

The present work addresses Au(III) extraction from chloride media using phosphonium-based ionic liquid (Cyphos IL 109) as a novel anion exchanger diluted in xylene. Gold(III) is extracted into the organic phase as [P66614+][AuCl4– ] and can easily be stripped by reduction to Au(I) with CS(NH2)2/HCl or Na2S2O3. A series of extraction-stripping cycles show a possible recirculation of used solvent without loss of performance, as far as the extraction of gold(III) from HCl/Cl– media is concerned. Au(III) was quantitatively (99.4%) extracted from 0.1 mol L–1 HCl initially containing 100 mg L–1 Au(III) with 0.8 g L–1 Cyphos IL 109 with two counter-current stages at O/A = 1, whereas total stripping as Au(I) with 0.02 mol L–1 CS(NH2)2 in 5% HCl or 0.02 mol L–1 Na2S2O3 also needed two counter-current stages, at O/A = 3. Simulations of counter-current modes reveal Cyphos IL 109 can be considered a promising new extractant for complete recovery of Au(III) from Cl– media in pilot scale.

This paper focuses on the extractive separation and selective recovery of cobalt, nickel and lithium from the sulfate leachate of cathode scrap generated during manufacture of lithium ion batteries (LIBs). The conditions for extraction, scrubbing and stripping of cobalt from nickel and lithium are optimized with an aqueous feed containing 25.1 g·dm−3 cobalt, 2.54 g·dm−3 nickel and 6.2 g·dm−3 lithium using Na-PC-88A. 99.8% Co is extracted with 60% Na-0.56 mol·dm−3 PC-88A in two counter-current stages at an O/A phase ratio of 3/1 and an equilibrium pH of 4.5. The “crowding effect” shown for the first time provides effective scrubbing of impurities (Ni and Li) with 2.0 g·dm−3 CoSO4 solution. The McCabe-Thiele diagram predicts the scrubbing of 99.9% Ni and 99.9% Li at an equilibrium pH of 4.75 and O/A of 2/1 in two stages. High purity (99.9%) cobalt sulfate along with Ni and Li from the leach liquor of cathode scrap is recovered by solvent extraction. The proposed process ensures complete recycling of the waste of the manufacturing process of LIBs.

The present paper is focused on solvent extraction of hazardous Cd(II) from acidic chloride media by Cyanex 921, a new extractant mixed with 10% (v/v) TBP in xylene. The optimum conditions for extraction and stripping of Cd(II) were investigated with an aqueous feed of 0.1 mol/L Cd(II) in 2.0 mol/L HCl. McCabe-Thiele diagram was in good agreement with the simulation studies, showing the quantitative extraction (99.9%) of Cd(II) within two counter-current stages utilizing 0.30 mol/L Cyanex 921 at O/A ratio of 3/2 in 10 min. Stoichiometry of the complexes extracted was determined and confirmed by numerical treatment and graphical method, revealing the formation of HCdCl3 · 2L and HCdCl3 · 4L for Cyanex 921(L) concentration in the range 0.03-0.1 mol/L and 0.1-1.0 mol/L, respectively. The thermodynamic parameters for the extraction of cadmium were also determined. The stripping efficiency of cadmium from the loaded organic with 0.10 mol/L HCl was 99.6% in a three-stage counter-current process at an O/A ratio of 2/3. Cyanex 921 was successfully applied for the separation of Cd(II) from Ni(II) in the simulated leach liquor of spent Ni-Cd batteries. The study demonstrates the applicability of the present hydrometallurgical approach for the treatment of hazardous waste, the spent Ni-Cd batteries.