Recovery of nickel,cobalt, copper and zinc in sulphate and chloride solutions using synergistic solvent extraction

A number of synergistic solvent extraction (SSX) systems have been developed to recover nickel, cobalt, zinc and copper from sulphuric and chloride leach solutions by the solvent extraction team of CSIRO, Australia. These in-clude (1) Versatic 10/CLX50 system for the separation of Ni from Ca in sulphate solutions, (2) Versatic 10/4PC system for the separation of Ni and Co from Mn/Mg/Ca in sulphate solutions, (3) Cyanex 471X/HRJ-4277 system for the separation of Zn from Cd in sulphate solutions, (4) Versatic 10/LIX63 system for the separation of Co from Mn/Mg/Ca in sulphate solutions, (5) Versatic 10/LIX63/TBP system for separation of Ni and Co from Mn/Mg/Ca in sulphate solutions, (6) Versatic 10/LIX63 system for the separation of cobalt from nickel in sulphate solutions by difference in kinetics, (7) Cyanex 272/LIX84 system for the separation of Cu/Fe/Zn from Ni/Co in sulphate solutions, (8) Versatic 10/LIX63/TBP system to recover Cu/Ni from strong chloride solutions, and (9) Versatic 10/LIX63 system to separate Cu from Fe in strong chloride solutions. The synergistic effect on metal separation and efficiency is presented and possible industrial applications are demonstrated. The chemical stability of selected SSX systems is also reported.     

Solvent extraction of praseodymium using different extractants – a synergistic study

The extraction of praseodymium was investigated from chloride media using different extractants such as D2EHPA, PC88A, Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301, Cyanex 302, LIX 84I, LIX 622N, Alamine 336, Aliquat 336 and their mixtures. The synergistic effect of Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301 and Cyanex 302 were studied with each other. Among all the combinations, the mixtures of Cyanex 921-Cyanex 301 and Cyanex 923-Cyanex 301 showed the synergistic effect on the extraction of praseodymium. Solvent extraction of Pr was carried out with the mixture of 0.5 M Cyanex 301 and 0.5 M Cyanex 923. The McCabe-Thiele diagram indicated the quantitative extraction of Pr in two counter-current stages at an A:O phase ratio of 1:2. The two-stage counter-current simulation study showed 94% of extraction efficiency.     

Chemical Reactivity of Tributyl Phosphate with Selected Solvent Extraction Reagents

It has recently been shown that Cyanex 272 can react with tributyl phosphate (TBP) to form the corresponding butyl ester species under both commercial and anhydrous operating conditions. The present work found that acidic organic extractants MEHPA, DEHPA, Ionquest 801, Cyanex 302, Cyanex 301, and decanoic acid also react with TBP to form the corresponding butyl ester species and dibutyl phosphate under anhydrous conditions at 65°C, whereas non-acidic reagents Alamine 308, LIX 84, LIX 63, and Acorga M5640 do not. Excluding MEHPA, the rate of ester formation appears inversely correlated with the pKa of the organic acid used.     

Extraction and Separation of Zr(IV) and Hf(IV) from Nitrate Medium by Some CYANEX Extractants

Abstract

A solvent extraction study has been carried out to extract and separate zirconium and hafnium from nitrate medium by using some phosphine oxide extractants (CYANEX 921, CYANEX 923, and CYANEX 925) in kerosene. The influence of the different factors affecting the extraction process was studied in detail. Apparently the rate of extraction of Zr(IV) and Hf(IV) in CYANEX 921, CYANEX 923, and CYANEX 925 is reasonably fast. The extraction increases with increasing temperature, suggesting that the reaction is endothermic. The stripping percent of Zr(IV) and Hf(IV) by 0.5 M HNO₃ from the loaded organic phase after two stages reached 97.5% and 10.2%, respectively, which lead to good separation of the two metals. Under the optimum conditions, the extraction of zirconium was about 90, 87.6, and 91.6% and separation factors equal to 17, 21.4, and 40.7 were obtained for CYANEX 921, CYANEX 923, and CYANEX 925, respectively. The results obtained reveal that 2.0 M nitric acid is the optimum acid concentration for the separation of Zr(IV) and Hf(IV) and 0.4 M CYANEX 925 performs more efficient separation compared with other organophosphorus extractants.     

Separation and Recovery of Light Rare-Earths from Chloride Solutions using Organophosphorus based Extractants

In this paper, separation possibilities of light rare-earths (LREs), Ce, La, Nd, and Pr with three acidic organophosphorus extractants such as TOPS 99 (an equivalent of di-2-ethylhexyl phosphoric acid, D2EHPA), PC 88A(2-ethylhexylphosphonic acid mono-2-ethylhexyl ester), and Cyanex 272 (Bis(2,4,4-trimethylpentyl)phosphinic acid) from synthetic chloride solutions of monazite at three initial pH values has been investigated. The composition of synthetic leach liquor is Ce ? 5.4 g/L, La ? 3.12 g/L, Nd ?1.35 g/L, and Pr ? 0.475 g/L at pH 2.0. Using sodium hypochlorite and sodium hydroxide, cerium was precipitated as ceric hydroxide quantitatively. Among the three investigated extractants, TOPS 99 showed better separation factors towards LREs. Therefore, 0.7 mol/L TOPS 99 has been employed for the separation of Nd, and Pr from La in 3-stages at an aqueous to organic phase ratio of 4:1 and pH 2.0. Raffinate contains 2120 mg/L La, 41 mg/L of Nd, and 17 mg/L of Pr corresponding to an extraction efficiency of 32.1%, 96.4%, and 96.2%, respectively. La from loaded organic phase was scrubbed with 9182 mg/L Nd solution and achieved a scrubbing efficiency of 98.2%. 1 mol/L HCl is used for quantitative stripping. A process flowsheet for the separation and recovery of LREs was presented.     

The Hafnium-Selective Extraction Fom a Zirconium(Hafnium) Heptafluoride Ammonium Solution Using Organophosphorus-Based Extractants

ABSTRACT

The suitability of the organophosphorus-based extractants, DiOPA, Ionquest 801 and D2EHPA was evaluated for the selective extraction of Zr and Hf from an (NH₄)₃Zr(Hf)F₇ acidic solution using both dispersive and pertraction solvent extraction (SX). A stock solution of (NH₄)₃Zr(Hf)F₇ was dissolved in either HCl or H₂SO₄ (0.1–8 M). The following extraction variables were investigated: type and concentration of the acidic solution, the contact time, and extractant to metal ratio. Subsequently, the stripping was investigated using (NH₄)₂CO₃, CaCl₂, H₂SO₄ and C₂H₂O₄ in the concentration ranges of 0–2 M. During extraction, scrubbing and stripping using D2EHPA, CaCl₂ and C₂H₂O₄, the Zr purity was increased from 97.2% to 99.0%. When extracting from 4 M H₂SO₄ with 9 wt% D2EHPA, a Hf selectivity of 32% was observed where after stripping with C₂H₂O₄ resulted in a 98.7% recovery of Zr. With 1.2 M CaCl₂ as stripping liquor, almost no Hf and 75% Zr stripping was obtained. During the pertraction 72% Hf and 44% Zr extraction was achieved after 180 min when extracting with 9 wt% D2EHPA from 4 M H₂SO₄. Pertraction based stripping with 1.2 M C₂H₂O₄ yielded 75% of both Zr and Hf, while stripping with 2 M CaCl₂ resulted in 58% Hf stripped with almost no Zr stripping.     

Separation of Cadmium,Cobalt, and Nickel by Solvent Extraction using the Nickel Salts of the Extractants

A new solvent‐extraction process for the separation of cadmium, cobalt, and nickel in sulphate solutions coming from the hydrometallurgical processing of spent Ni‐Cd batteries is proposed. The main innovation is to use nickel salts of the extractants, thus avoiding external pH control in the extraction operation. The extractants are first loaded with nickel in conditioning steps, using a neutralizer for pH control, and afterwards contacted with the aqueous processing solutions for extraction of interested metals with no further need of neutralization. This process is an alternative to the usual approach, which uses the sodium or ammonium salts of the extractants, avoiding introducing these cations in the process stream. Using this approach, the extraction of cadmium with nickel salt of 1 M DEHPA was performed at resulting pH values of 3.8–4.3 producing an organic phase loaded with 35 g/L Cd. Cobalt extraction with the nickel salt of Cyanex 272 was further achieved at resulting pH of 5.1–5.7 obtaining a organic loaded with 6.5 g/L Co.     

Synergistic Effect of D2EHPA and Cyanex 272 on Separation of Zinc and Manganese by Solvent Extraction

The effect of bis-2-ethylhexylphosphoric acid (D2EHPA), bis (2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272), and tri-butyl phosphate (TBP) and their mixtures in various proportions for the separation and extraction of zinc and manganese from sulfate solutions were investigated. Experiments were carried out in the pH range of 0.5–5.0 at 25, 40, and 60°C. It was shown that the extraction of zinc and manganese by D2EHPA and/or Cyanex 272 can be increased by the increase in pH and temperature. The synergistic extraction and separation of zinc and manganese with a mixture of D2EHPA and Cyanex 272 was studied and the results showed that mixing the two extractants improved the extraction capacity of the mixture. Increasing the D2EHPA to Cyanex 272 ratio in the organic phase, caused a right shifting of extraction isotherms of manganese and zinc; shifting the manganese curve was more than zinc. The manganese curve had considerable right shifting with 5% D2EHPA and 15% Cyanex 272. TBP did not affect the zinc (Zn) and manganese (Mn) extraction. The stoichiometric coefficients of Zn and Mn were determined with 20% and 5% D2EHPA and 15% Cyanex 272 by applying the slope analysis method. The organic phase was stripped by sulfuric acid.     

Comparison of separation behavior of Ir(IV) and Rh(III) between tin(II) chloride and ascorbic acid as a reducing agent in the extraction with Cyanex 921 and Cyanex 301

In order to compare the separation of Ir(IV) and Rh(III) between SnCl₂ and ascorbic acid as a reducing agent, solvent extraction with Cyanex 921 and Cyanex 301 was investigated in the HCl concentration range from 1 M to 9 M. Addition of both SnCl₂ and ascorbic acid led to the selective extraction of rhodium by the two extractants, leaving Ir(III) in the raffinate. Since tin was selectively extracted over Rh(I) in the presence of SnCl₂, it is necessary to separate Rh(I) and tin by selective stripping from the organic phase. In the presence of ascorbic acid, the extraction percentage of rhodium by Cyanex 921 was much smaller than that in the presence of SnCl₂. UV spectra was analyzed to verify the reduction reaction of both metal ions. FT-IR was analyzed between fresh and loaded organic solution. The reduction of Ir(IV) and Rh(III) in the presence of ascorbic acid was explained. Selective stripping of Rh(I) over tin from the loaded Cyanex 921 was obtained by the mixture of HCl and (NH₂)₂CS.     

Extraction of Lanthanum and Samarium from Nitrate Medium by some Commercial Organophosphorus Extractants

Abstract

The extraction of lanthanum(III) and samarium(III) from nitrate solutions by some phosphine oxide compounds (Cyanex 921, Cyanex 923, and Cyanex 925) in kerosene was investigated. The influence of the different factors affecting the extraction was studied in detail. The extraction of these metals using the above extractants was compared and the sequence of extraction was found to be Cyanex 921>Cyanex 923?Cyanex 925. The stripping percent of La(III) and Sm(III) by 0.75 M HNO₃ from the loaded organic phase after two stages were 72% and 5.2%, respectively, which could enable a good separation between these two lanthanides.     

Mechanistic study of hafnium and zirconium extraction with organophosphorus extractants

Research on the purification of Zr has increased in the last few decades and although effective processes have been developed, little is known about the mechanism of Hf and Zr extraction; particularly, at low acid concentrations. This study’s aim was to determine the influence of alterations in alkyl substituents on the extraction mechanism of Hf and Zr from sulfate media. Seven organophosphorus extractants (Dio-PA, TPPA, DPPA, TPPO, TPPS, D2EHPA and Ionquest 801) were screened with four of them (Dio-PA, DPPA, D2EHPA and Ionquest 801) resulting in promising extraction results. This was attributed to the activity of the acidic hydroxy phosphinyl (=P(O)OH) group which is responsible for the dimerization and cation exchange properties of the extractant. The extractant and hydrogen ion stoichiometries involved in the extraction mechanism were determined for these four extractants by slope analysis from extractant- and acid-variation experiments. It was found that Dio-PA, D2EHPA, and Ionquest 801 extract via a cation-exchange mechanism, according to [M(OH)₂]²⁺ + 2 HA ? M(OH)₂A₂ + 2 H⁺. In contrast, the extraction with DPPA was best described by a solvated cation exchange (SCE) mechanism, according to [M(OH)]³⁺ + 6 HA ? M(OH)A₃.3HA + 3 H⁺. It was concluded that the presence of electron-withdrawing substituents produced softer Lewis base extractants, which favored the extraction of Hf over Zr from acidic sulfate media.     

Solvent extraction of zirconium(IV) from acidic chloride solutions using the thiosubstituted organophosphorus acids Cyanex 301 and 302

Solvent extraction of zirconium(IV) from acidic chloride solutions has been carried out with the thiosubstituted organophosphorus acids Cyanex 301 and Cyanex 302. The extraction follows an ion exchange mechanism: MO²⁺_(aq) + 2 HA_(org) ? MOA_2(org) + 2 H⁺_(aq), where, M = Zr(IV); HA = Cyanex 301 or Cyanex 302. The plots of log D (distribution ratio) vs log [HA], are linear with slopes of 2, indicating the association of two moles of extractant with the extracted metal species. The plots of log D vs log [H⁺] gave straight lines with a negative slope of 1.7 for Cyanex 301 and 1.8 for Cyanex 302, indicating the exchange of two moles of hydrogen ions for every mole of Zr(IV). Addition of sodium salts enhanced the extraction of metal. The stripping behavior of metal from the loaded organic (LO) with HCl and H₂SO₄ was studied. Increase of temperature during the extraction and the stripping stage increases the metal transfer, showing the process is exothermic. Mixed extractants, the extraction behavior of associated elements such as Hf(IV), Ti(IV), Al(III), Fe(III) and the IR spectra of the metal complexes were studied. Copyright © 2004 Society of Chemical Industry     

Extraction and Separation of Germanium Using Cyanex 301/Cyanex 923. Its Recovery from Transistor Waste

Abstract

The extraction of Ge(IV) from HCl, HNO₃ and H₂SO₄ media in toluene solution of Cyanex 301 and Cyanex 923 is investigated. It is almost quantitatively extracted (～95%) in Cyanex 301 and Cyanex 923 at 8 molL^?1 HCl but the extractions from H₂SO₄ and HNO₃ are poor in the entire investigated range of acid molarity. Detailed investigations were carried out from HCl medium. Based on the slope analysis data the extracting species is identified as GeCl₄·2R (R=Cyanex 301/Cyanex 923). The extraction of Ge(IV) is higher and comparable in diluents like toluene, n‐hexane and kerosene (160–200°C) and there is no correlation between the dielectric constant and the percent extraction. The extractants are stable towards prolonged acid contact and there is negligible loss in their extraction efficiency even after recycling them for several cycles. The extraction behavior of commonly associated metal ions namely As(V)/(III), Sn(IV), Tl(III), In(III), Ga(III), Fe(III), Al(III), Hg(II), and Cu(II) has also been investigated. Based on the partition data conditions for attaining some binary and ternary separations involving Ge(IV) have been optimized. The separation data have been fused to develop a scheme for the recovery (93%) of pure germanium (～99%) from semi conductor waste.     

Uranium Permeation from Nitrate Medium Across Supported Liquid Membrane Containing Acidic Organophosphorous Extractants and their Mixtures with Neutral Oxodonors

Permeation of U(VI) from nitric acid solution has been studied across supported liquid membrane (SLM) using bis[2,4,4 trimethyl pentyl] phosphinic acid (Cyanex 272) either alone or in combination with neutral donors like Cyanex 923 (a mixture of four trialkyl phosphine oxides viz. R₃PO, R₂R′PO, RR′₂PO, and R′₃PO where R: n-octyl and R′: n-hexyl chain), TBP (tri-n-butyl phosphate), and TEHP (tris-2-ethylhexyl phosphate) dissolved in n-paraffin as carriers. Effect of various other parameters such as nature and concentration of receiver phase, feed acidity, uranium concentration, pore size, and membrane thickness on U(VI) transport across SLM were investigated. Transport behavior of U(VI) was also compared with other derivatives of phosphoric acids like 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A), dinonyl phenyl phosphoric acid (DNPPA) under identical conditions and it followed the order: Cyanex 272 > PC88A > DNPPA. 2 M H₂SO₄ was suitable for effective U(VI) transport across SLM. Presence of neutral donors in carrier showed significant enhancement in U(VI) permeation in the order: Cyanex 923 > TBP > TEHP. U(VI) transport decreased with increased membrane thickness as well as decrease in pore size. The optimized conditions were tested for recovery of U(VI) from uranyl nitrate raffinate (UNR) waste generated during purification of uranium.     

Analysis of the Interaction between Organophosphorus Acid and Tertiary Amine Extractants in the Binary Mixtures by Fourier Transform Infrared Spectroscopy (FT-IR)

In the synergistic solvent extraction of rare earth elements by binary mixtures of organophosphorus acid and tertiary amine extractants, the extraction reaction depends on the nature and strength of the interaction between the two extractants in the mixtures. In order to correlate qualitatively the interaction in different mixtures, the FT-IR spectra for organophosphorus acid (D2EHPA, PC88A, and Cyanex 272) and tertiary amine (Alamine 336 and TEHA) extractants and their mixtures have been analyzed. The primary focus was on investigating the changes in the characteristic functional groups of acidic and amine extractants in the binary mixtures as the strength and concentration of these extractants varied. IR spectroscopy of the organics confirmed the interaction in the binary mixtures, and strength of the interaction increased with the increase in the acidity of acidic extractant and the basicity of the amine extractant.     

Reagent Degradation in the Synergistic Solvent Extraction System LIX®63/Versatic™10/Nonyl-4PC

Direct solvent extraction of nickel and cobalt from nitrate-based leach liquors has become of interest due to the successful piloting of nitric acid processes for treating nickel laterite ores. The current study investigated the stability of both hydroxyoxime and nonyl-4PC (nonyl-4-pyridine carboxylate) in LIX 63/Versatic 10/nonyl-4PC under conditions relevant to the recovery of nickel and cobalt from a nitrate-based leach liquor with stripping into sulfuric acid. Nonyl-4PC increased both the rate of hydroxyoxime degradation under the pH 1.5 extract conditions required for a potential nickel–cobalt separation process and the rate of cobalt poisoning of LIX 63. Under strip conditions and the pH 4 extract conditions required for co-extraction of nickel and cobalt, nonyl-4PC did not otherwise affect the rate of hydroxyoxime loss. Additionally, the presence of nitrate anions did not increase the loss of either hydroxyoxime or nonyl-4PC. The combination LIX 63/Versatic 10/nonyl-4PC therefore appears prospective for the co-extraction of nickel and cobalt at pH 4 from nitrate-based leach liquors.     

Effect of organic extractants on the electrocrystallization of nickel from aqueous sulphate solutions

The effect of the presence of commercial organic extractants LIX 84I, Cyanex 272, D2EHPA, Versatic 10 and TBP with or without Mg²⁺ on various electrodeposition parameters for nickel deposition on stainless steel cathode from aqueous sulphate solutions was investigated. The parameters included cathodic current efficiency, deposit morphology, crystal orientation and cathodic polarization. There was no significant variation in the current efficiency in the presence of these additives, but changes were observed in the deposit morphologies and crystal orientations even though all the deposits were bright, smooth and coherent. Changes were also observed in the cathodic polarization behaviour during nickel electrocrystallization in the presence of these additives. The effect of the additives on the electrokinetic parameter, exchange current density (i ₀) has also been investigated.     

Kinetics,Equilibrium, and Thermodynamic of Pb(II) Biosorption by Citric Acid Modified Lawny Grass Containing Cyanex272

Lawny grass loaded Cyanex272 prepared by solid-liquid grind was used to remove Pb(II) in the batch and column process. Carboxylic groups were introduced to the grass by citric acid modification and Cyanex272 was successfully immobilized on grass. The removal rate of Pb(II) on 272-1CG is close to 100%. Cyanex272 also played an important role in improving maximum adsorption capacities from 328 to 380 mg/g and shortening equilibrium time from 60 min to 40 min. Thermodynamic results indicate the adsorption of Pb(II) is spontaneous and endothermic. 0.1 mol/L HCl is used as eluent and desorption percentages reach 95.1%.     

Recovery of hydrochloric acid from galvanizing industrial effluents

The recovery of hydrochloric acid and its separation from iron, zinc and minor elements, in the galvanizing pickling baths, were studied by solvent extraction (SX) and distillation and by distillation and crystallization. Several extractants were tested, the tri-isooctyl amine, Alamine 308, the primary aliphatic amine Primene JM-T and the mixture of four trialkylphosphine oxides, Cyanex 923. Only Cyanex 923 enabled distillation. The results indicated the feasibility of the processes to treat a real effluent using Cyanex 923 and to obtain high HCl concentrations in the distillate (256–330 g/L).     

Process for the Recovery of Cobalt and Nickel from Sulphate Leach Liquors with Saponified Cyanex 272 and D2EHPA

Abstract

In this paper, a process is reported for the recovery of cobalt and nickel from copper raffinate solutions using partially saponified Cyanex 272 and D2EHPA as the extractants. The aqueous feed contains 1.65 g/L cobalt and 16.42 g/L nickel. More than 99.9% cobalt separation was achieved with 0.13 M Cyanex 272 (60% neutralized with alkali) in two counter‐current stages at an aqueous to organic phase ratio of 1.1:1. Co‐extraction of nickel was 0.18% only. Stripping of cobalt from a loaded organic phase was carried out with synthetic spent electrolyte solution at an organic to aqueous phase ratio of 2.5 in two counter‐current stages to generate a pregnant electrolyte solution to produce cobalt metal by electrowinning. Similarly, optimum conditions for nickel extraction with 60% neutralized 1 M D2EHPA at O/A ratio of 1.4 in 2 two stages and stripping of metal with synthetic spent electrolyte at O/A ratio of 1.6 in two stages were standardized. Extraction and stripping efficiencies were >99% and the flowsheet of the process is demonstrated.