Separation of cobalt and zinc from concentrated nickel sulfate solutions with Cyanex 272

BACKGROUND: Removal of cobalt and zinc from concentrated nickel solutions separately using two Cyanex 272 circuits has been practised in the nickel industry. However, no detailed study has been conducted and data are scarce for further improvement. This study aims to optimise the operating conditions and to simplify the process flowsheet. RESULTS: With a synthetic solution containing 100 g L^?1 Ni, 1.4 g L^?1 Co and 0.8 g L^?1 Zn and the organic solution containing Cyanex 272 and TBP in Shellsol D70, the operating conditions of extraction, scrubbing and stripping were optimised. McCabe–Thiele diagrams were constructed to determine the theoretical extraction and stripping stages and a flowsheet to separate cobalt and zinc from nickel was proposed. With this flowsheet, more than 99% cobalt and zinc could be separated, resulting in a pure nickel solution with less than 10 mg L^?1 of cobalt and zinc. CONCLUSIONS: The current study shows that Cyanex 272 can be used to separate cobalt and zinc in one Cyanex 272 circuit effectively from concentrated nickel solutions to obtain very pure nickel solutions suitable for nickel electrowinning or hydrogen reduction. The cobalt and zinc in the loaded strip liquor were concentrated over 10 times and can be separated readily in another much smaller solvent extraction circuit. Copyright © 2010 Society of Chemical Industry     

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.     

Simultaneous solvent extraction of cobalt and magnesium in the presence of nickel from sulfate solutions by Ionquest 801

The simultaneous extraction of Co(II) and Mg(II) from nickel sulfate solutions has been carried out using the organophosphonic extractant Ionquest 801 diluted in Exxsol D‐80. Statistical design and analysis of experiments were used in order to determine the main effects and interactions of the solvent extraction parameters, which were the extraction pH at equilibrium, the temperature, the extractant concentration and the organic/aqueous phase ratio. A statistically designed experiment was also carried out to study the stripping of the Ionquest 801 organic phase loaded with cobalt and magnesium by sulfuric acid solution. The number of stages required for both extraction and stripping processes of cobalt and magnesium was evaluated. The results of continuous counter‐current mini‐plant tests demonstrated the simultaneous recovery of cobalt and magnesium from nickel sulfate solution. Copyright © 2005 Society of Chemical Industry     

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.     

Separation of Cadmium from Cobalt Electrolyte Solution by Solvent Extraction Method Using Modified D2EHPA

Cadmium from high tenor cobalt electrolyte solution was selectively removed using modified di-(2-ethylhexyl) phosphoric acid (D2EHPA). In this study, D2EHPA was converted to Co-D2EHPA after replacing its functional group with Co²⁺ ions. The process parameters, such as pH, organic concentration, O/A ratio, kinetics, etc., were investigated. A significant amount of cadmium was extracted using Co-D2EHPA at equilibrium pH ～ 3.5 and the McCabe-Thiele diagram showed that 100% cadmium can be extracted through three stages using O/A ratio of 1. Stripping tests revealed that 100% cadmium can be stripped from the loaded organic using 0.4 M H₂SO₄ in a single contact.     

Separation and Recovery of Cadmium from Acidic Leach Liquors of Spent Ni-Cd Batteries using Molten Paraffin Wax Solvent Extraction

Separation and recovery of cadmium from sulphate leach liquors of spent Ni-Cd batteries using TBP, HDEHP (D2EHPA), EHEHPA (PC 88A or Ionquest 801 or P507) have been investigated in a laboratory scale. Cadmium can be extracted into paraffin waxes from acidic solutions in the temperature range of 55–75°C using different extractants. The influence of various parameters on extraction and stripping were studied in detail. The feasibility of separation of cadmium from nickel using these extractants and their combination was studied. The mixture extractant of EHEHPA and TBP was found to be the best for the separation of Cd and Ni. A three-stage counter-current extraction simulation test for cadmium extraction was carried out at an A/O phase ratio of 4:1 and pH 2.5. More than 99.97% Cd²⁺ was extracted with the organic phase containing 0.7 mol L^?1 EHEHPA and 0.5 mol L^?1 TBP, while more than 99.97% nickel was left in the raffinate. The cadmium loaded organic phase was stripped with 2 mol L^?1 hydrochloric acid in the stripping stage. The present method can be applied to the separation and recovery of cadmium from acidic leach liquor of spent Ni-Cd batteries or related waste liquor.     

Purification of nickel sulphate solutions containing iron,copper, cobalt,zinc and manganese

Acidic nickel-bearing solution containing iron, cobalt, manganese, zinc and copper was processed through a solvent extraction and precipitation technique to obtain a pure nickel sulphate solution. Iron was extracted using 0.2M Cyanex-272 (partially neutralised) as the extractant. Stripping of iron from the loaded organic has also been studied. After iron recovery through solvent extraction the raffinate still contained 0·25 g dm^?3 of iron which was quantitatively separated by a lime precipitation technique. During this iron precipitation there was no loss of cobalt and nickel but copper, manganese and zinc were coprecipitated to some extent. From the iron-free nickel sulphate solution the other impurities were extracted using the same extractant (Cyanex-272) in a single stage. The metal ions from the loaded organic were stripped using a 0·5% (v/v) H₂SO₄ solution in a single stage. The entire operation needs only seven stages: two stages for iron extraction, three stages for iron stripping from the loaded organic, and one stage each for extraction and stripping of other impurities. In the entire operation the loss of nickel was less than 0·5%.     

Removal of Nickel from Electroless Nickel Plating Rinse Water with Di(2‐Ethylhexyl)phosphoric Acid‐Impregnated Supports

Abstract

Electroless nickel plating technology is playing an increasingly important and indispensable role in many fields such as the electronic and automobile industries. As a result, the treatment of the rinse water containing about 50 mg/dm³ of nickel is becoming a serious environmental problem. Although this water is currently treated by the conventional precipitation method, a method without sludge generation is highly desired. This study explores the possibility of removing and recovering nickel from the rinse water with di(2‐ethylhexyl)phosphoric acid‐impregnated supports (D2EHPA‐IS). Macroporous polymer and oil adsorbents made of synthetic and natural fibers as the supporting materials were tested for the nickel removal abilities from simulated rinse water. In the batch experiments, more than 90% of the nickel can be adsorbed by these D2EHPA‐IS without pH adjustment. The adsorption of nickel reaches the equilibrium within 1.2 ks at 298K at a shaking rate of 140 rpm. The pH‐dependency of the nickel adsorption by the D2EHPA‐IS shows that the nickel is adsorbed by a cation exchange reaction. The adsorbed nickel can then be readily eluted with mineral acids. Most of the IS can be used many times without losing their adsorption abilities. In the column experiments, the breakthrough curves of nickel for these supports indicate that the nickel–D2EHPA complex formed at the high nickel loading region tends to dissolve into the aqueous phase. These findings lead to the conclusion that most of the studied D2EHPA‐IS are effective for the removal and recovery of nickel from an electroless nickel plating rinse water in batch mode.     

Extraction and recovery of rhodamine B,methyl violet and methylene blue from industrial wastewater using D2EHPA as an extractant

The extraction behavior of cationic dyes namely rhodamine B (RB), methyl violet (MV) and methylene blue (MB) from industrial wastewater has been investigated using di-(2-ethylhexyl) phosphoric acid (D2EHPA) in hexane as a carrier. The extraction of cationic dyes increases with decreasing feed phase pH and increasing D2EHPA concentration in organic phase. The stripping percentage of dyes using acetic acid as the stripping agent from loaded D2EHPA was found to increase with increasing acid concentration. 98% stripping efficiency of dyes was achieved with 8.5 mol/L acetic acid solution at an organic:aqueous phase ratio (O/A) of 2:1. Parameters examined include D2EHPA concentration, effect of diluents, effect of pH, effect of initial dye concentration, equilibration time, and various stripping agents, aqueous to organic phase ratio in extraction and organic to aqueous phase ratio in stripping.     

Separation and recovery of heavy metals from concentrated smelting wastewater by synergistic solvent extraction using a mixture of 2-hydroxy-5-nonylacetophenone oxime and bis(2,4,4-trimethylpentyl) -phosphinic acid

Extraction and separation of copper, zinc, nickel, and cadmium from calcium and magnesium in concentrated smelting wastewater by synergistic solvent extraction using a mixture of 2-hydroxy-5-nonylacetophenone oxime (Mextral 84H) and bis(2,4,4 -trimethylpentyl)-phosphinic acid (Cyanex 272) in an aliphatic diluent (DT-100) was studied. The effects of extractant concentrations, equilibrium pH, organic-to-aqueous phase ratios, system temperature, and extraction and stripping efficiencies on the extraction performance of the heavy metals were investigated. Extraction of pH isotherms showed that addition of Cyanex 272 to Mextral 84H causes obvious synergistic shifts for zinc and cadmium and a slightly antagonistic shift for nickel. The separation factor of cadmium over magnesium was 155.7 and the ΔpH₅₀ values between the metals were over 1.00 pH units. Semi-continuous tests for the metals extraction, scrubbing, and stripping were conducted in a continuous extraction apparatus with conditions further optimized for separation of the metals. Nearly 100% of the copper and nickel and over 98% of the zinc and cadmium were recovered with less than 0.1 mg/L copper and nickel, 26 mg/L of zinc, and 10 mg/L of cadmium remaining in the raffinate. A process in which all valuable metals are extracted simultaneously and stripped selectively at optimal conditions is proposed that is entirely feasible for the separation of copper, zinc, nickel, and cadmium from calcium and magnesium in concentrated smelting wastewater. The study determines the fundamental parameters for the treatment of smelting wastewater by solvent extraction.     

Solvent Extraction Studies for Separation of Zn(II) and Mn(II) from Spent Batteries Leach Solutions

This study aims at assessing the possibility of using solvent extraction processes for separating Zn(II) and Mn(II) dissolved in aqueous solutions obtained by acid bioleaching of spent alkaline and Zn-C batteries. In this context, Cyanex 272 and DEHPA were tested as extractant agents, and the former was shown to have better performance. Hence, the effect of four factors (equilibrium pH, extractant concentration, A/O ratio, and temperature) into three response variables (extraction efficiency of Zn, Y_Zn; extraction efficiency of Mn, Y_Mn; separation factor, β) were tested according to a full factorial design (2⁴) with two replicated center points. Our study revealed that Y_Zn depends mainly on the extractant concentration, Y_Mn on the equilibrium pH and β on the equilibrium pH, extractant concentration, and A/O ratio as well as on second and third order interactions. One extraction step is sufficient to reach high extraction of zinc in synthetic solutions, but two stages were required for real leaching liquor. The extraction kinetics is fast (less than 15 min) for both metals, even when real liquor was tested. The organic solvent can be efficiently recovered using a stripping solution of H₂SO₄ 1 M and thus the process can be considered environmentally sustainable.     

Separation of cobalt and nickel from acidic sulfate solutions using mixtures of di(2‐ethylhexyl)phosphoric acid (DP‐8R) and hydroxyoxime (ACORGA M5640)

DP‐8R and ACORGA M5640 extractants diluted in Exxsol D100 were used to co‐extract cobalt and nickel from aqueous acidic sulfate media. The influences of equilibration time, temperature, equilibrium pH and reagent concentrations on the extraction of both metals have been studied. It was observed that both cobalt and nickel extraction are slightly sensitive to temperature but are pH dependent. Metal extraction equilibria are reached within about 5 min contact time. In addition, cobalt extraction depends on the extractant concentration in the organic phase. For a solution containing 0.5 g dm^?3 each of cobalt and nickel and an initial pH of 4.1, conditions were established for the co‐extraction of both metals and selective stripping (with H₂SO₄) of cobalt and nickel. Using the appropriate reagent concentrations the yield (extraction stage) for both metals exceeded 90%, and stripping of cobalt and nickel was almost quantitative. Copyright © 2004 Society of Chemical Industry     

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.     

SOLVENT EXTRACTION OF COBALT AND NICKEL IN BIS (2,4,4-TRI-METHYLPENTYL) PHOSPHINIC ACID, “CYANEX -272”

ABSTRACT A study has been made of the extraction of cobalt and nickel from sulfate solutions into bis(2,4,4 tri-methylpentyl) Phosphinic acid - “Cyanex 272”, diluent Esso solvent DX 3641, for both high and low metal loading in the organic phase. In dilute solution, 0.01 M, extraction constants and enthalpies were determined for both metals. The extraction of cobalt was always favored over that of nickel, increasing with increase in temperature. No structure change with temperature was found for the cobalt-Cyanex complex. Phase modifiers were found to effect the selectivity of “Cyanex 272” for cobalt.

At high metal loading, equilibrium curves for cobalt were fitted using semi-empirical curve fitting, while for nickel a straight line variation was observed. Organic phase polymerization was observed for both metals the degree of aggregation increasing with increase in loading. A step change increase in the viscosity of the organic phase was observed at high cobalt loading. Phase modifiers proved to be ineffective In reducing the increase in organic phase viscosity.     

Cobalt removal from waste‐water by means of supported liquid membranes

BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste‐water. In the present work, the removal of Co(II) from a synthetic CoSO₄ solution containing initial amounts of cobalt(II) in the range 100–200 ppm (0.1–0.2 g dm^?3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di‐2‐ethyl‐hexylphosphoric acid (D2EHPA) and 5‐dodecylsalicylaldoxime (LIX 860‐I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid–liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui‐Cel Extra‐Flow 4 × 28) having a surface area of 19 m², a steady Co(II) flux of 0.140 gm^?2h^?1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm^?3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860‐I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry     

Solvent Extractive Separation of Zirconium and Hafnium from Hydrochloric Acid Solutions by Organophosphorous Extractants and Their Mixtures with Other Types of Extractants

From 1 to 4 M HCl medium, zirconium was selectively extracted over hafnium by organophosphorous extractants (D2EHPA, PC88A, Cyanex 272). In order to increase the separation factor Zr/Hf, mixtures of organophosphorous extractants with amines (Alamine 336, Aliquat 336) or cationic extractants (Versatic acid 10, LIX 63) were employed in 1–4 M HCl medium. Mixtures with Versatic acid 10 and LIX 63 led to depression in the extraction percentages. But the mixture with LIX 63 was found to be the most effective in separating the two metals among the extractant systems tested in this study. The highest separation factor of around 9.5 was obtained with a mixture of 0.01 M LIX 63 + 0.05 M Cyanex 272 at HCl concentration of 2–4 M. The Zr and Hf were effectively stripped from the loaded mixture of LIX 63 + Cyanex 272 by sulfuric acid solution.     

Flüssig/Flüssig‐Extraktion von Indium aus sauren Lösungen

The extraction of indium from a synthetic sulfate‐containing solution using commercial reagents (Cyanex 272, DEHPA, and Cyanex 923) is evaluated on a comparative basis. The extraction profiles of indium (III) were examined with regard to the reagent concentration, the pH value of the aqueous solution, and the indium concentration in a low phase ratio of 1:10. DEHPA and Cyanex 272 are, in contrast to Cyanex 923, very well suited for the extraction of indium. Re‐extraction with HCl and H₂SO₄ is compared.     

Cobalt–manganese separation: The extraction of cobalt(II) from manganese sulphate solutions by cyanex 301

The extraction and stripping reactions of cobalt(II) by Cyanex 301 in Iberfluid diluent from aqueous manganese sulphate solutions has been investigated. The effect of different variables which should influence the extraction-stripping of cobalt was evaluated, including equilibration time, temperature, organic diluent, extractant concentration, aqueous pH, cobalt loading, strip solution concentration, etc. The number of stages required for the extraction and stripping of cobalt was also evaluated. The results were used to define the conditions for the purification of manganese sulphate solutions. © 1998 Society of Chemical Industry     

Solvent Extraction of Au(I) from Auro‐Cyanide Solution with Cetyltrimethylammonium Bromide/Tri‐n‐Butyl Phosphate System using Column‐Shaped Extraction Equipment

Abstract

Solvent extraction of Au(I) from alkaline cyanide solution containing several milligram per liter of gold was investigated with column‐shaped extraction equipment using tri‐n‐butylphosphate (TBP) as extractant with addition of quaternary ammonium salt, cetyltrimethylammonium bromide (CTAB), directly into the aurous aqueous phase in advance. The influences of the volume of TBP and the NaCl concentration in the aurous aqueous phase on Au(I) extraction were investigated. The experimental results for treating 50 L of synthetic auro‐cyanide solution containing 10 mg/L Au(I) and for treating real auro‐cyanide leaching liquor by CTAB/TBP system were reported. The results obtained establish that the column‐shaped extraction equipment was suitable for extracting Au(I) from low content auro‐cyanide solution at high aqueous/organic phase ratio, and that more than 97% of gold(I) could be extracted while the Au(I) concentration in the raffinate was less than 0.3 mg/L. In addition, the stripping of Au(I) from the loaded organic phase and the recycle of the organic phase were also discussed.