Studies into the separation of the component metals of chrome residue

Chrome residue, the disposal product of a chrome ore pyrometallurgical extraction process, contains a number of valuable metals in oxide form. The bulk extraction of the main metals in residue is investigated by acid dissolution, followed by solvent extraction techniques for the selective recovery of the metals from solution. Efforts have been focused on screening for Cr(III) extractants, and parameter optimization for maximizing extraction efficiency and selectivity of suitable extractants. The implications for a potential process are discussed. This thesis presents laboratory results of studies to determine optimum dissolution and selective metal extraction conditions and reagents

The solvent extraction behaviour of chromium with Bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex [R] 272)

The bulk of the world's known nickel reserves are contained in laterite ores but sulphidic ores remain the main source of the Western world's nickel production. With the continuing increase in nickel consumption and the depletion of sulphidic ores, the traditional source of nickel, the extraction of nickel from lateritic ores has been the subject of research interest worldwide. Advances in pressure acid leaching (PAL) technology have resulted in significant commercial attempts to extract nickel from these ores. Leaching the ore with sulphuric acid at elevated temperatures and pressures allows almost complete dissolution of the nickel and cobalt, a valuable byproduct of these ores, but yields highly contaminated pregnant leach solutions. Separating and purifying the nickel and cobalt from these solutions remains a hindrance to full commercial production. Several purifying techniques have been commercialised but all suffer from continuing technical problems. Among them, however, the direct solvent extraction (DSX) technique offers several advantages. Direct solvent extraction involves the separation of the nickel and cobalt directly from the partially neutralised pregnant liquor stream (PLS) by solvent extraction with Cyanex(R) 272 as the extractant. However certain contaminants adversely affect the solvent extraction process. Among them is chromium and little is known about the solvent extraction behaviour of this metal. The present work investigated the solvent extraction of chromium with Cyanex(R) 272. It was found that the solvent extraction behaviour of chromium(III) and chromium(VI), both of which could be found in PAL-generated PLS, are distinctly different.For chromium(III), solvent extraction tests showed that (a) it is extracted in the pH range 4-7; (b) the extraction is partly influenced by diffusion; (c) the apparent equilibration time is significantly longer than most transition metals; (d) increases in temperature from 22 to 40 C resulted in increases in the extraction; (e) the pH0.5 increases in the order nitrate < chloride < sulphate in the presence of these anions; (f) the presence of acetate depresses extraction of chromium(III) when the solution is allowed to stand before extraction; (g) in the PLS, chromium(III) precipitated at lower pH than that predicted by the solubility product principle; and (h) the pH0.5 decreases as the Cyanex(R) 272 concentration increases. Chromium(III) is initially extracted by solvation of its inner sphere complex, which then undergoes further reaction in the organic phase leading to the formation of a much more stable species that is difficult to strip. A reaction scheme together with a description of both the initially extracted and resulting stable species is proposed. Extraction of chromium(VI), on the other hand, (a) occurs at pH less than 2 by solvation of chromic acid; (b) is independent of the aqueous phase composition; (c) does not occur in the pH range (3-6) used in the separation of nickel and cobalt. The latter is irrespective of temperature up to 40 C, the use of industrial PLS as the aqueous phase or the presence of an anti-oxidant in the organic phase. The stripping of chromium(III) from a loaded organic phase can be achieved using 1-4 mol L-1 mineral acids provided the stable organic species have not formed making industrial scale stripping of chromium(III) from Cyanex(R) 272 difficult. The exact composition of the aqueous phase during extraction affects the stripping efficiency

Towards the recovery of rare earth elements from end-of-life products : hydrometallurgical routes and mathematical modelling of extraction systems

The rare earth elements (REEs) are essential ingredients for the development of modern industry and the transition to a more sustainable economy model. The unique physicochemical features of these elements, such as their magnetism and optical properties, are greatly expanding their application. They have become key elements for the manufacture of many ordinary consumer goods like hybrid cars, fluorescent lamps or electronic devices like mobile phones or tablets. The growing popularity of the rare earth elements derivatives is leading to an increase in the global demand and the price of these elements. Unfortunately, the current availability of these resources is limited due to three main factors: their heterogeneous geological location, their low concentration in the ores, and the environmental issues related with their mining. All these disadvantages concerning the supply of the rare earth elements have led to the study of new techniques to obtain them, such as the recycling of end-of-life products. Recycling of REEs arises as a new secondary source of supply of REEs, especially in Europe where large amounts of technological waste are generated every year. Currently, the recycling of rare earth elements represents less than 1% of the global supply. Nevertheless, some studies in the literature assume that by 2050 the recovery rate of REEs will be 90% for wind turbines, 70% for electrical vehicles and 40% for the rest of derivative products. The research presented in this thesis relies on experimental investigation of new hydrometallurgical routes, the majority of them involving the use of ionic liquids, which could eventually be applied for the recovery of rare earth elements from end-of-life products. Matemathical modelling of the reported extraction systems has been carried out in order to provide a computational instrument that can be easily tailored for prediction of other collecting processes requiring minor adjustments.Les terres rares son ingredients essencials per al desenvolupament de la indústria moderna i la transició cap a un model econòmic més sostenible. Les seves característiques físico-químiques úniques, com el seu magnetisme i propietats òptiques, han precipitat un increment accelerat en l’aplicació d’aquests elements. Les terres rares s’han convertit en elements clau per a la fabricació de molts articles d’ús diari com per exemple, cotxes elèctrics i dispositius electrònics com telèfons mòbils i tabletes. La creixent popularitat dels productes que contenen aquests metalls està provocant un escalat en la demanda global i el preu de les terres rares. Desafortunadament, en l’actualitat, la disponibilitat d’aquests recursos a la natura és limitada degut bàsicament a tres factors: heterogènia localització geològica, baixa concentració als minerals que els contenen i inconvenients mediambientals relacionats amb la mineria. Els inconvenients relacionats amb el subministrament de les terres rares a nivell mundial han propiciat l’estudi de noves tècniques per a la obtenció d’aquests elements mitjançant el reciclatge de productes que els contenen. El reciclatge sorgeix com una font secundària alternativa a la mineria per tal d’assegurar el provisionament de terres rares especialment a Europa, on generem grans quantitats de residus tecnològics cada any. Actualment, la taxa de reciclatge de terres rares se situa per sota l'1% del subministrament global. No obstant, alguns estudis publicats en la literatura assumeixen que l’any 2050, la taxa de recuperació haurà augmentat considerablement, de manera que es reciclarà fins a un 90% de les terres rares provinents d’aerogeneradors, 70% de vehicles elèctrics i 40% de la resta de productes que contenen aquests metalls. La recerca presentada en aquesta tesi es basa, principalment, en la investigació de noves rutes hidrometal·lúrgies, la majoria d’elles utilitzant líquids iònics, que puguin ser implementades en processos de recuperació de terres rares a partir de residus tecnològics. D’altra banda, s’han elaborat models matemàtics dels sistemes d’extracció reportats que pretenen convertir-se en una eina computacional, fàcilment adaptable, per a la predicció del comportament d’extracció en d’altres processos de recuperació amb diferents condicions experimentals

Towards the recovery of rare earth elements from end-of-life products : hydrometallurgical routes and mathematical modelling of extraction systems

Aplicat embargament de la tesi des de la data de defensa fins al juny de 2020. Tesi amb diferents seccions retallades per drets de l'editor.The rare earth elements (REEs) are essential ingredients for the development of modern industry and the transition to a more sustainable economy model. The unique physicochemical features of these elements, such as their magnetism and optical properties, are greatly expanding their application. They have become key elements for the manufacture of many ordinary consumer goods like hybrid cars, fluorescent lamps or electronic devices like mobile phones or tablets. The growing popularity of the rare earth elements derivatives is leading to an increase in the global demand and the price of these elements. Unfortunately, the current availability of these resources is limited due to three main factors: their heterogeneous geological location, their low concentration in the ores, and the environmental issues related with their mining. All these disadvantages concerning the supply of the rare earth elements have led to the study of new techniques to obtain them, such as the recycling of end-of-life products. Recycling of REEs arises as a new secondary source of supply of REEs, especially in Europe where large amounts of technological waste are generated every year. Currently, the recycling of rare earth elements represents less than 1% of the global supply. Nevertheless, some studies in the literature assume that by 2050 the recovery rate of REEs will be 90% for wind turbines, 70% for electrical vehicles and 40% for the rest of derivative products. The research presented in this thesis relies on experimental investigation of new hydrometallurgical routes, the majority of them involving the use of ionic liquids, which could eventually be applied for the recovery of rare earth elements from end-of-life products. Matemathical modelling of the reported extraction systems has been carried out in order to provide a computational instrument that can be easily tailored for prediction of other collecting processes requiring minor adjustments.Les terres rares son ingredients essencials per al desenvolupament de la indústria moderna i la transició cap a un model econòmic més sostenible. Les seves característiques físico-químiques úniques, com el seu magnetisme i propietats òptiques, han precipitat un increment accelerat en l’aplicació d’aquests elements. Les terres rares s’han convertit en elements clau per a la fabricació de molts articles d’ús diari com per exemple, cotxes elèctrics i dispositius electrònics com telèfons mòbils i tabletes. La creixent popularitat dels productes que contenen aquests metalls està provocant un escalat en la demanda global i el preu de les terres rares. Desafortunadament, en l’actualitat, la disponibilitat d’aquests recursos a la natura és limitada degut bàsicament a tres factors: heterogènia localització geològica, baixa concentració als minerals que els contenen i inconvenients mediambientals relacionats amb la mineria. Els inconvenients relacionats amb el subministrament de les terres rares a nivell mundial han propiciat l’estudi de noves tècniques per a la obtenció d’aquests elements mitjançant el reciclatge de productes que els contenen. El reciclatge sorgeix com una font secundària alternativa a la mineria per tal d’assegurar el provisionament de terres rares especialment a Europa, on generem grans quantitats de residus tecnològics cada any. Actualment, la taxa de reciclatge de terres rares se situa per sota l'1% del subministrament global. No obstant, alguns estudis publicats en la literatura assumeixen que l’any 2050, la taxa de recuperació haurà augmentat considerablement, de manera que es reciclarà fins a un 90% de les terres rares provinents d’aerogeneradors, 70% de vehicles elèctrics i 40% de la resta de productes que contenen aquests metalls. La recerca presentada en aquesta tesi es basa, principalment, en la investigació de noves rutes hidrometal·lúrgies, la majoria d’elles utilitzant líquids iònics, que puguin ser implementades en processos de recuperació de terres rares a partir de residus tecnològics. D’altra banda, s’han elaborat models matemàtics dels sistemes d’extracció reportats que pretenen convertir-se en una eina computacional, fàcilment adaptable, per a la predicció del comportament d’extracció en d’altres processos de recuperació amb diferents condicions experimentals.Postprint (published version

Counter-current separation of cobalt(II)–nickel(II) from aqueous sulphate media with a mixture of Primene JMT-Versatic 10 diluted in kerosene

This work claims the use of the mixture of Primene®JMT-Versatic 10 [HJMT+·Versatic-] IL diluted in Kerosene as an extractant for cobalt/nickel separation from sulphate media by solvent extraction technique, its application on a continuous counter-current device is possible because the presence of Primene®JMT in the organic phase allows us to maintain the pH of the equilibrated aqueous phase at an almost stable value. The solvent extraction of cobalt and nickel ions is studied as a function of the extractant concentration in the organic phase and the concentration of both metals. By constructing the McCabe–Thiele diagram, we found that four steps are necessary to separate the cobalt(II) from the nickel(II) in sulphate media. A simulated continuous counter-current experiment corroborated the McCabe–Thiele predictions, obtaining a raffinate containing 83% of the inlet nickel with a purity of 99.9%, working with an A:O ratio 1:2This work was supported by the Spanish Ministry ofEconomy and Competitiveness, MINECO grant number [CTM2017–83581–R].Postprint (updated version

Selective recovery of metals from citric acid leach solutions during the recycling of lithium-ion batteries

Thesis (PhD)--Stellenbosch University, 2022.ENGLISH SUMMARY: Recycling has become an imperative part of the lithium-ion battery (LIB) life cycle due to growing demand for energy storage in applications like electric vehicles and renewable energy technologies, as well as government legislations requiring the recycling of LIBs to reduce environmentally harmful waste. LIB recycling processes must therefore aim to provide a secondary source for strategically scarce metals, like lithium and cobalt, while seeking to reduce the environmental impact of LIB waste. This project aimed to develop a hydrometallurgical process based on environmentally-friendly reagents to recover manganese, lithium, cobalt, and nickel in separate product streams from end-of-life lithium-ion batteries. Organic acids are effective lixiviants in hydrometallurgical recovery of metals from scrap LIBs, having the added benefit of being more environmentally benign than mineral acids. Among these organic acids, citric acid exhibits similar extraction performance when compared to mineral acids. Leaching LiCoO2 (LCO) and LiNixMnyCozO2 (NMC) cathode powder following dismantling and aluminium removal with 1.5M citric acid, 2 vol.% H2O2 at 95°C and 20 g/L for 20 minutes, achieved 93% Al, 90% Co, 96% Li, 94% Mn, and 94% Ni dissolution, confirming citric acid’s performance as lixiviant. A combination of solvent extraction and precipitation technologies was then used to sequentially separate cobalt, lithium, manganese, and nickel from the citric acid leach solution. A diverse range organic extractants, namely: Versatic 10, Cyanex 272, PC-88A, D2EHPA, LIX 84-IC, LIX 984N-C, TBP, Alamine 308, Alamine 336, and Aliquat 336TG was screened to determine which metals can be selectively separated from the citrate leach solution. It was concluded that manganese and residual aluminium are best separated from the PLS under strong acidic conditions with D2EHPA, after which lithium can be separated under weak acidic conditions with D2EHPA in a second subsequent extraction. The cobalt and nickel were separated poorly by the organic extractants and would thus be separated by precipitation from the lithium extraction raffinate. The first separation of manganese and trace aluminium was optimized with 12 vol.% D2EHPA in kerosene at a pH of 2.5 and O/A ratio of 2 when using 3 counter current stages, which separated 99.9% Mn and 80% Al from the PLS. The co-extraction of other metals under optimum conditions was determined to be 7.7% Co, 12.1% Li, and 4.9% Ni. Comparable stripping performance was achieved with sulphuric acid and citric acid from the loaded organic and thus citric acid was chosen as stripping agent. Optimal stripping of the aluminium and manganese loaded organic was achieved with 1.5M citric acid at an A/O ratio of 2, where 78% Mn and 20% Al was stripped in a single stage. The novel second, sequential extraction separated 93.6% Li to a reversible 3rd phase under weak acidic conditions where the optimal lithium separation was achieved with 23 vol.% D2EHPA in kerosene at a pH 5.5 and O/A ratio of 4 with 3 counter-current stages. The co-extraction during the optimum lithium separation included 6.6% Co and Ni. The lithium loaded 3rd phase and diluent emulsion was selectively stripped with 1.5M citric acid and an A/O ratio of 1 to recover 71% Li with 24% Co and Ni in one stage. Optimal nickel precipitation from the lithium extraction raffinate using DMG was achieved with a Ni/DMG ratio of 0.2 at a pH of 8, which enabled 98.5% Ni precipitation with 20% Co co-precipitation. The final effluent from the process had a 96.1 wt.% cobalt purity (metal basis) in the aqueous phase. This hydrometallurgical process was therefore capable of effectively separating the LIB metals from an organic acid PLS to individual metal product streams.AFRIKAANS SUMMARY: Herwinning het ’n noodsaaklike deel van die litiumioonbattery (LIB) se lewensiklus geword as gevolg van die groeiende vereiste vir energieverberging in toepassings soos elektriese voertuie en hernubare energietegnologieë, sowel as regeringswetgewing wat die herwinning van LIBs vereis om skadelike afval vir die omgewing te verminder. LIB-herwinningprosesse moet daarom beoog om ’n sekondêre bron vir strategiese skaars metale, soos litium en kobalt, te voorsien, terwyl ook gepoog word om die omgewingsimpak van LIB- afval te verminder. Hierdie projek het beoog om ’n hidrometallurgiese proses gebaseer op omgewingsvriendelike reagense te ontwikkel om mangaan, litium, kobalt, en nikkel in aparte produkstrome te herwin uit end-van-lewe litiumioonbatterye. Organiese sure is effektiewe loogmiddels in hidrometallurgiese herwinning van metale uit LIB-skroot, wat die toegevoegde voordeel het om meer omgewingsvriendelik te wees as mineraalsure. Onder hierdie organiese sure, het sitroensuur soortgelyke ekstraksiedoeltreffendheid getoon as dit vergelyk word met mineraalsure. Loging van LiCoO2 (LCO) en LiNixMnyCozO2 (NMC) katodepoeier na demontering en aluminiumverwydering, met 1.5 M sitroensuur, 2 vol.% H2O2 by 95 °C en 20 g/L vir 20 minute, het 93% Al, 90% Co, 96% Li, 94% Mn, en 94% Ni-oplossing bereik, wat sitroensuur se doeltreffendheid as loogmiddel bewys. ’n Kombinasie van oplosmiddelekstraksie en presipitasietegnologieë is toe gebruik om kobalt, litium, mangaan, en nikkel sekwensieel uit die sitroensuurloogoplossing te skei. ’n Diverse verskeidenheid organiese ekstraheermiddels, naamlik Versatic 10, Cyanex 272, PC-88A, D2EHPA, LIX 84-IC, LIX 984N-C, TBP, Alamine 308, Alamine 336, en Aliquat 336TG is gekeur om te bepaal watter metale selektief geskei kan word van die sitraatloogmiddel. Dit is vasgestel dat mangaan en residuele aluminium die beste geskei kan word van die logingsoplossing (PLS) onder sterk suur kondisies met D2EHPA, waarna litium geskei kan word onder swak suur kondisies met D2EHPA in ’n tweede opeenvolgende ekstraksie. Die kobalt en nikkel is swak geskei deur die organiese ekstraheermiddels en sou dus geskei moes word deur presipitasie uit die litiumekstraksieraffinaat. Die eerste skeiding van mangaan en spooraluminium is geoptimeer met 12 vol.% D2EHPA in keroseen by ’n pH van 2.5 en O/A-ratio van 2 wanneer drie teenstroomfases gebruik word, wat 99.9% Mn en 80% Al van die PLS geskei het. Die koëkstraksie van ander metale onder optimum kondisies is bepaal as 7.7% Co, 12.1% Li, en 4.9% Ni. Vergelykbare stropingdoeltreffendheid is bereik met swawelsuur en sitroensuur uit die gelaaide organiese middel en dus is sitroensuur gekies as stropingsmiddel. Optimale stroping van die aluminium-en- mangaan-gelaaide organiese middel is bereik met 1.5 M sitroensuur by ’n A/O-ratio van 2, waar 78% Mn en 20% Al gestroop is in ’n enkel fase. Die nuwe tweede, sekwensiële ekstraksie het 93.6% Li geskei na ’n omkeerbare derde fase onder swak suur kondisies waar die optimale litiumskeiding bereik is met 23 vol.% D2EHPA in keroseen by ’n pH 5.5 en O/A- ratio van 4 met drie teenstroomfases. Die koëkstraksie gedurende die optimale litiumskeiding het 6.6% Co en Ni ingesluit. Die litium-gelaaide derde fase en verdunde emulsie is selektief gestroop met 1.5 M sitroensuur en ’n A/O-verhouding van 1 om 71% Li te stroop met 24% Co en Ni in een fase. Optimale nikkelpresipitasie van die litiumekstraksierafinaat deur die gebruik van dimetielglioksim (DMG) is bereik met ’n Ni/DMG-verhouding van 0.2 by ’n pH van 8, wat 98.5% Ni-presipitasie met 20% Co- kopresipitasie in staat gestel het. Die finale uitvloeisel van die proses het ’n 96.1 wt.% kobaltsuiwerheid (metaalbasis) in die waterige fase gehad. Hierdie hidrometallurgiese proses is daarom in staat om die LIB- metale doeltreffend van ’n organiese suur PLS te skei, met individuele metaalprodukstrome.Master

Extraction and separation of zirconium and hafnium using octanol

Zirconium (Zr) and hafnium (Hf) metals have drawn considerable attention due to their various applications, especially in the nuclear industry where zirconium is used as a cladding material for nuclear reactors due its low neutron-capture cross-section and strong resistance to corrosion, whereas hafnium is used as an excellent control rod material for reactors due to its high neutron-absorption capacity. The efficiency of the reactor depends directly on the concentration of hafnium in zirconium. The zirconium should contain a very low concentration of hafnium, not exceeding 100 ppm, for use in the nuclear industry. Due to the fact that zirconium and hafnium occur within the same mineral, there is great interest in separating them in order to produce zirconium and hafnium oxide which can be used in the production of zirconium and hafnium metals appropriate for use in the nuclear industry. Hence, the separation and purification of these elements is of great importance. Solvent extraction techniques are employed to separate and purify these elements on an industrial scale. However, the separation of zirconium and hafnium is a difficult task as both elements exhibit similar chemical and physical properties. The main objective of this investigation was therefore to evaluate the potential of octanol as an alternative extractant to the conventional extractants methyl isobutyl ketone (MIBK) and tributyl phosphate (TBP) due to the problems associated with the latter two extractants. The effect of the different parameters affecting the extraction and separation of these two elements (Zr and Hf) were studied in terms of the initial feed concentration, contact time, extractants, loading capacity, temperature, diluents and stripping agents. It was determined from the results obtained that the different parameters investigated all have important effects on the extraction and separation of zirconium from hafnium. The results indicate that zirconium ions were preferentially extracted over hafnium with undiluted 1-octanol and 2-octanol in 10 % hydrochloric acid and 1.5 M potassium fluoride as feed concentration at a ratio of 1:2. The McCabe-Thiele diagram indicates that four equilibrium stages are required for almost complete extraction of zirconium from the aqueous solution. Sulfuric acid was found to be the most desirable agent for stripping zirconium from the loaded organic solution. A mixture of oxalic acid and nitric acid was considered to be a good stripping agent for hafnium as it could lead to good separation of hafnium from the remaining zirconium. Zirconium and hafnium were neutralized using 25 % ammonium hydroxide solution. After filtration and calcination, the products obtained were characterised using XRD and SEM-EDS analysis. A packed column was also used to compare the effectiveness of the extraction and separation of zirconium from hafnium. It was observed that in order to achieve the optimum mass transfer, greater column height is required.Thesis (PhD)--University of Pretoria, 2019.Chemical EngineeringPhDUnrestricte

Fast contact copper extraction

The intensification of copper solvent extraction was examined in this thesis. Extraction with hydroxyoximes is used in industry for copper separation. The reaction between hydroxyoxime and copper is a two-phase interfacial complexation reaction in which aqueous copper cations exchange with hydrogen ions bound to hydroxyoxime. As extraction is an interfacial reaction, its rate is dependent on the area between phases, that is, an interfacial area (A). Moreover, the rate depends on the stagnant interfacial boundary layer thickness, or diffusion path length (l di f). These variables depend on droplet size, which in turn depends on the mixing conditions in the reactor. Intensified mixing will lead to intensified extraction. Copper extraction kinetic studies were conducted in different contactors. The mass transfer into a single droplet was examined using a concentration determination method based on image analysis. The image analysis method was also used to determine mass transfer into individual droplets during breakage and coalescence experiments. The mass transfer was found to increase during droplet breakage but not during coalescence. The increased mass transfer in breakage was due to an increase in interfacial area and mixing, as the breakage of rising droplet after collision with a blade is a more violent process than coalescence. The coalescing droplets were stationary, and the interfacial area decreased, which led to a constant mass transfer during coalescence. The other devices used in the studies were a conventional stirred tank and rotor-stator devices with intensified mixing. The rotor-stator devices were used in both batch and continuous-flow reactors. The main difference between these reactors and earlier intensified extractors, such as AKUFVE1 or high speed stirring in Morton flask, is the use of a rotor-stator mixer, which leads to intensified mixing in a smaller equipment volume. The kinetic data were modeled using a reactor models developed for copper extraction. The extraction is a two-phase reaction; its equilibrium is dependent on conditions in both phases. This is indicated by a decrease in the extraction equilibrium constant as a function of aqueous phase ionic strength. In a similar manner, the increase in diluent solubility parameter leads to a decrease in equilibrium constant. The kinetic constant of copper extraction increases as a function of mixing intensity. In order to characterize mixing conditions in extraction, the droplet sizes and mixing power were measured. Measurements were made in conventional stirred tank and rotor-stator mixed continuous flow reactor and the droplet sizes were correlated with mixing power. The starting point was a single droplet extraction without mechanical stirring, which naturally yielded the lowest kinetic constant value. As expected the rate increased in a conventional stirred tank as the impeller speed increased, whereas other variables, such as feed concentrations were kept constant. The increase in impeller speed enhanced extraction both in batch and in continuous-flow rotor-stator mixers. Short residence times are required for extraction in rotor-stator reactors because of high mixing intensities. The kinetic reaction constant (k) data of all stirred reactors were dependent on specific mixing power input (P/m) to exponent 0.625. The specific mixing power input was varied in three orders of magnitude when using LIX 984 extractant. The mixing intensity was varied here in a much wider range than in typical mass transfer measurement studies. A comparison of data with other copper extractants revealed that the correlation had reasonable agreement with the kinetic data over five orders of magnitude of P/m. The kinetic constants (k) determined in different devices (single droplet, stirred tank, and rotor-stator reactors) had a good correlation with A2/l di f. The interfacial area and diffusion path length (l di f) depend on droplet size and, on mixing power. Area and diffusion path length cannot vary independently in stirred reactors. Kinetic constant dependence on interfacial area and diffusion path length illustrates the interfacial nature of solvent extraction