Palladium Extraction from Nitric Acid Solutions by LIX 84 and LIX 860-I

ABSTRACT

The extraction of Pd(II) from weakly nitric acid solutions by LIX 84 (2-hydroxy-5-nonylacetophenone oxime) and LIX 860-I (5-dodecylsalicylaldoxime) dissolved in toluene has been studied and compared from the viewpoint of extraction equilibria. The effects of pH, nitrate ions and metal and extractant concentrations on the palladium distribution ratio have been quantified. The extraction rate of Pd(II) from this media is slow but the metal is quantitatively extracted by adding just the stoichiometric amount of the extractants. The experimental data have been treated graphically and numerically by means of the Letagrop-Distr program and can be explained by assuming the formation of the chelate PdL₂. Values of the extraction constants are also given.     

Solvent Extraction of Copper from Nitrate Media with Chelating LIX‐Reagents: Comparative Equilibrium Study

Abstract

Comparative experimental studies were carried out on extraction of copper(II) cations from aqueous acid nitrate media using four LIX‐reagents, representatives of different extractant classes: LIX 984N‐I, LIX 860N, LIX 84‐I and LIX 65N. As a diluent, liquid hydrocarbon undecane was used. The extraction behavior of the LIX‐reagents was compared based on an analysis of the influence of the main factors on the two‐phase mass transfer process: aqueous pH‐value, initial copper and extractant concentrations, and temperature. The experimental data received were used in the calculation of important parameters characterizing the efficiency of copper extraction from nitrate media with different LIX reagents: distribution ratios D, concentration extraction constants K _ex, pH_0.5‐values, and thermodynamic parameters such as enthalpy, entropy, and free energy changes (ΔH ⁰, ΔS ⁰, ΔG ⁰‐values).     

EXPERIMENTAL STUDIES AND PARAMETER OPTIMIZATION OF SEPARATION OF COPPER USING HOLLOW FIBER–SUPPORTED LIQUID MEMBRANE

The separation of copper from a leach liquor bearing 204.59 mol/m³ Cu, 40.83 mol/m³ Zn, 33.94 mol/m³ Co, 255.58 mol/m³ Ni, and 75.72 mol/m³ (NH₄)₂SO₄ has been carried out with a hollow fiber membrane using LIX 84-I as the mobile carrier. Central composite inscribed (CCI) design was used to design the experiments. The factors considered for the CCI design were pH, LIX 84-I concentration in the membrane phase, flow rate, and acid concentration in the strip solution. A reduced quadratic model was found to fit the experimental data. Detailed analysis of the effect of different factors as well as their interaction on the extraction of copper has been done. The optimized condition for maximum copper flux was found to be pH 4.5, 39.88% LIX 84-I, 360 mL/min flow rate, and 7% H₂SO₄ in strip solution. The highest copper flux of 7.46 × 10^?5 mol/m² · s was obtained experimentally at the above conditions, which is in good agreement with the predicted value of 7.57 × 10^?5 mol/m² · s.     

Solvent extraction with LIX 973N for the selective separation of copper and nickel

LIX 973N diluted with Iberfluid was used to co‐extract copper and nickel from ammoniacal/ammonium carbonate aqueous media. The influence of equilibration time, temperature, equilibrium pH and extractant concentration on the extraction of both metals has been studied. It was observed that neither copper nor nickel extraction is sensitive to temperature and equilibrium pH, however nickel extraction equilibrium is reached at a longer contact time (20 min) than that of copper (5 min), in addition nickel extraction depends greatly on the extractant concentration in the organic phase. For a solution containing 3 g dm⁻³ each of copper and nickel and 60 g dm⁻³ ammonium carbonate, conditions were established for the co‐extraction of both metals, ammonia scrubbing and selective stripping (with H₂SO₄) of nickel and copper. Using the appropriate extractant concentration the yield (extraction stage) for both metals is near 100%, whereas the percentage of nickel and copper stripping is also almost quantitative. © 1999 Society of Chemical Industry     

Extraction of molybdenum(VI) from sulfate solutions by LIX 622

The application of LIX 622 (oxime derivative) as an extraction reagent of molybdenum (VI) from sulfate media was studied. The extraction system was studied as a function of contact time, temperature, aqueous pH, diluent of the organic phase and metal and extractant concentrations. The extraction is exothermic and it is dependent on the organic diluent, aqueous pH and reagent concentration. The data have been analysed numerically to determine the stoichiometry of extracted species and their equilibrium constants. It was found that molybdenum was extracted into the organic phase by a complex mechanism which involves the formation of three species (MoO₂L₂, MoO₄H₃HL⁺HSO₄⁻ and MoO₄H₂HL, where L represents the extractant). Molybdenum stripping by acidic and ammonium hydroxide solutions was also studied. © 2000 Society of Chemical Industry     

Experimental and Theoretical Investigation of Distribution Equilibria and Kinetics of Copper(II) Extraction with LIX 84 I and TFA

Batch experiments of copper(II) extraction at equilibrium were carried out in a temperature controlled stirred cell to extract copper(II) with LIX 84-I and 1,1,1-trifluoro-2,4-pentanedione (TFA) diluted in either n-heptane, tetradecane, MIBK, or n-decanol at 298 and 313 K. Extraction efficiency and capacity of copper(II) extraction with acid extractants at equilibrium were measured and analyzed using a theoretical model based on equilibrium extraction kinetics. Experimental and theoretical investigations revealed that TFA and n-decanol are found to be an efficient extractant and diluent, respectively, for copper(II) extraction with high values of extraction capacity.     

Recovery of copper from ammoniacal/ammonium sulfate medium by LIX 54

The extraction‐stripping reaction of Cu(II) by LIX 54 in Iberfluid from aqueous ammonium sulfate medium at pH 8.5 has been investigated. The effects of pH, metal ion, extractant concentration as well as the loading capacity of the reagent were studied. The extraction equilibrium constant for copper was determined numerically to be 7 × 10⁻⁷. Experimental data can be explained assuming the formation of CuR₂ species in the organic phase (R represents the extractant). Copper stripping was studied using typical spent copper electrowinning solutions as stripping medium. The number of stages required for the extraction and stripping of copper was also evaluated. The results were used to asses the conditions for purification of industrial waste solutions (eg spent etchants) containing copper through counter‐current extraction‐stripping. © 1999 Society of Chemical Industry     

Solvent extraction of gold by LIX 79: experimental equilibrium study

The extraction of gold(I) from aurocyanide aqueous solutions using LIX 79 has been studied. Different variables that could affect the extraction system were evaluated: equilibration time, aqueous pH, metal and extractant concentrations, organic phase diluent and aqueous ionic strength. The extraction of the aurocyanide complex with respect to other metal‐cyano complexes has also been studied on both synthetic and real leach solutions. Gold experimental data have been analysed numerically to determine the stoichiometry of extracted species and its equilibrium constant. It was found that gold(I) was extracted into the organic phase by the formation of the species RHAu(CN)₂ (LIX 79=R). Stripping of gold from loaded organic phases was carried out using NaOH or NaCN solutions. © 1999 Society of Chemical Industry     

Mechanistic study of active transport of copper (II) using LIX 54 across a liquid membrane

The present work describes the mechanism of active transport of copper(II) through an immobilized liquid membrane (ILM) containing LIX 54 (β‐diketone) dissolved in Iberfluid as mobile carrier. An uphill transport model has been described and equations have been derived taking into account aqueous boundary layer diffusion and liquid membrane diffusion as simultaneous controlling factors. In the present model, various cases were discussed using the carrier LIX 54 and different chemical species; the diffusional membrane resistance for lower and higher concentrations of extractant was evaluated. The diffusion coefficients were observed to decrease with increase in ­the extractant concentration, ranging from 4.1 × 10⁻³ to 1.65 × 10⁻² mol dm⁻³ Plotting [Cu]₀−[Cu]_t vs time resulted in a slope of [HR]₀A/2Δ_orgV taking into account the complex species, CuR₂, in the membrane. The mass transfer coefficient (Δ_org ⁻¹), the diffusion coefficient of the metal carrier species (D_org) and the thickness of the aqueous boundary layer were calculated from the proposed model for LIX 54. More than 90% of the Cu(II) could be separated using LIX 54 in the presence of various metals such as Ni, Co(II) and Zn. © 2000 Society of Chemical Industry     

Selective and Synergistic Extraction of Nickel from Simulated Cr-Ni Electroplating Bath Solutions using LIX 63 and D2EHPA as Carriers

The main goal of the present study is to explain synergistic extraction of nickel from simulated Cr-Ni electroplating bath solutions (SEBS) using 5,8-diethyl-7-hydroxydodecane-6-one oxime (LIX 63) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractants by emulsion liquid membrane (ELM) technique. The importance of membrane composition and aqueous phase properties on nickel extraction percentage has been highlighted for the selective extraction of nickel. Some important parameters like acid concentration, stripping solution type and concentration, mixing speed, extractant concentrations, phase ratio, and surfactant concentration was studied to improve the extraction and stripping efficiencies. Higher than > 99% of nickel was recovered at optimum conditions within 6 min. The higher separation factors (β_Ni/Cr) were obtained as 580. As a result, the nickel extraction kinetic with D2EHPA has been defined as faster than LIX63. So, the kinetic transport of nickel mainly depends on LIX63 than D2EHPA. According to these results, D2EHPA behaves as a synergistic extractant in the present extraction mechanism.     

Copper Solvent Extraction from Waste Cyanide Solution with LIX 7820

The use of a solvent mixture of a quaternary amine and nonylphenol (LIX 7820) to extract copper cyanide from waste cyanide solution has been studied. Copper extraction is favorable at low pH, whereas a high cyanide‐to‐copper ratio tends to suppress copper loading. The preferential extraction of Cu(CN)₃ ^2? over Cu(CN)₄ ^3? and CN^? has been confirmed by the examination of both the extraction of copper and cyanide by the solvent mixture under different experimental conditions. The solvent mixture also strongly extracted zinc and nickel from the cyanide solution, but it exhibits weak affinity for iron cyanide complex and free cyanide. The important findings suggested the potential application of the solvent mixture for the recovery of copper and cyanide from waste cyanide solutions, by which copper can be extracted and concentrated into a small volume of solution and the barren cyanide solution recycled to the cyanidation process.     

MODELING Cu EXTRACTION FROM ACIDIC SOLUTIONS USING P5100, PT5050, AND LIX 84

The Bureau of Mines studied the extraction of copper (II) from acidic sulfate solutions using commercial extractants LIX 84, P5100, and PT5050. Mathematical models, consisting of sets of nonlinear mass action and mass balance equations, were solved using a commercial equation-solving program on a personal computer. The models suggest that LIX 84 is a mixture of monomelic and dimeric extractant with an extraction equilibrium constant of 145 and a dimerization constant of 65 L/mol; PT5050 appears to be a monomeric extractant with an extraction equilibrium constant of 53; and P5100 shows more complex characteristics, with a monomeric extraction equilibrium constant of 400, a dimer formation constant of 3.7 L/mol, and a modifier-complex formation constant of 5.8 L/mol. For all models, the relative error of fit was less than 6%.     

TBP对LIX84由Cu2+-NH3-Cl——H2O系萃取铜及氨的影响

以Cu2+-NH3-Cl--H2O氨性溶液为被萃水相,在LIX84中添加磷酸三丁酯(TBP),考察了有机相中TBP浓度、被萃水相铜离子浓度、总氨浓度和pH值及相比、LIX84浓度对铜萃取率、共萃氨量的影响. 结果表明,随LIX84中TBP浓度升高,铜萃取率变化不大,负载有机相的共萃氨量明显降低. 有机相中TBP浓度为0.1 mol/L、LIX84浓度为40%、被萃水相铜离子浓度25 g/L、总氨浓度3 mol/L及pH值9.1、相比1:1、萃取时间30 min时,铜萃取率约为81%,与未添加TBP时基本一致,而负载有机相的共萃氨量由未添加TBP时的260 mg/L降至添加TBP后的85 mg/L.     

Co-extraction and selective stripping of copper (II) and molybdenum (VI) using LIX 622

LIX 622 diluted with kerosene was used to co-extract copper (II) and molybdenum (VI) from acidic sulphate solutions. The influence of equilibrium pH and extractant concentration on metal co-extraction has been studied. The extraction of both metals is sensitive to equilibrium pH; however, molybdenum is extracted preferably to copper at acidic pH values. For aqueous phases containing both metals, conditions were established for the co-extraction, selective stripping of copper and molybdenum and NH₃ removal from the stripped organic solution.     

Recovery of copper values from bio-heap leaching of low grade Malanjkhand chalcopyrite ore

M/S Hindustan Copper Limited (HCL), India generates large amounts of lean sulfide ores of copper. The current production of lean copper ores in India is 0.55 million tons with ∼0.3% average copper content. Heap-bioleaching of the lean copper ores in 15 and 30 ton scales was undertaken at IMMT, Bhubaneswar. The leaching study showed 0.09% dissolution of copper from the ore body per day. The leach liquor was processed through solvent extraction and electrowinning. Extraction of copper from the actual leach liquor was carried out with 1.5% LIX 622N in kerosene with zero co-extraction of iron. The copper-free raffinate was fed back to the leaching unit. Stripping of copper from the loaded organic was carried out with 180 kg/m³ H₂SO₄. The copper pregnant electrolyte was passed through a carbon column to make it free from entrained organic and was fed to the electrowinning unit. The increase in current efficiency was due to the increase in the concentration of electrolyte. The energy consumption was 1.7 kWh/kg at a flow rate of 4.5 L/h. Smooth and bright sheets of copper of 99.99% purity were obtained.     

Extraction of zinc from ammoniacal/ammonium sulphate solutions by LIX 54

The extraction of zinc from ammoniacal/ammonium sulphate aqueous media using LIX 54 has been studied. The metal extraction rate has been examined and also the effect of temperature on the extraction of zinc (ΔH° = −8·8 kJ mol⁻¹). The effect of the aqueous pH, and therefore zinc ammine complex formation, on the extraction of zinc was studied. Stripping of the metal from loaded organic phases was carried out at various rates, temperatures (ΔH° = 3·2 kJ mol⁻¹) and sulphuric acid concentrations. The results obtained were compared with others obtained from the literature wherein different extractants were used. © 1998 SCI.     

Separation of Cobalt and Zinc from Manganese,Magnesium, and Calcium using a Synergistic Solvent Extraction System Consisting of Versatic 10 and LIX 63

Abstract

The Boleo leach solution contains large amounts of manganese (45 g/L), magnesium (25 g/L) and small amounts of cobalt (0.2 g/L) and zinc (1 g/L) in sea water. Due to the high manganese concentration, it is very difficult to separate cobalt and zinc from manganese, magnesium, and calcium using conventional solvent-extraction processes, which has led to the development of a synergistic solvent extraction (SSX) system consisting of Versatic 10 and LIX®63. By adding 0.4 M LIX 63 to 0.5 M Versatic 10, large synergistic shifts were obtained for cobalt (max. ΔpH₅₀ 4.24) and zinc (max. ΔpH₅₀ 1.62). After a single contact at pH 4.5, the extraction of cobalt was almost complete and that of zinc 80%. The extraction of manganese was 1.55%, and almost no magnesium and calcium were extracted, indicating excellent separation of cobalt and good separation of zinc from manganese, magnesium, and calcium. The SSX system was further optimized to reduce the co-extraction of manganese with the synthetic Boleo demonstration plant solution. It was found that with 0.33 M Versatic 10 and 0.30 M LIX 63, the SSX system composition approached optimum. After a single contact at pH 5.5, the extractions of cobalt and zinc were 93% and 70%, respectively, while the manganese concentration in the loaded organic solution was only 0.28 g/L. The extraction and stripping kinetics of cobalt and zinc were rapid. The SSX system was tested in two integrated pilot-plant trials with excellent results. Baja Mining has planned to implement the SSX circuit in their future Boleo plant.     

SPECTROSCOPIC STUDY OF THE EXTRACTION OF NICKEL BY 2-HYDROXY-5-NONYLBENZOPHENONE OXIME (LIX 65N) AND 5,8-DIETHYL-7-HYDROXYDODECANE-6-ONE OXIME (LIX 63).

ABSTRACT

A novel method for determination of solvent extraction equilibria and kinetics using Infrared attenuated total reflectance spectroscopy (ATR) is described. The method allows complete, quantitative kinetic studies using a total of one gram of extractant. Solvent extraction of aqueous Ni²⁺ into 0.5 - 1.0 μm films of Apiezon M (ApM, aliphatic hydrocarbon) containing the title reagents was examined. In contrast with LIX 65N extraction which proceeds solely through the LIX 65N anion, extraction of Ni²⁺ by LIX 63 proceeds through both neutral and anionic forms of LIX 63. This results in a kinetic rate law having two terms, each exhibiting first order dependence on both [Ni²⁺] and [LIX 63]₀. For mixtures of LIX 65N and LIX 63 (LIX 63:LIX 65N ≤ 0.12) In the ApH films, the rate law has only one term, of orders [LIX 65N]₀ ¹, [LIX 63] ₀ ¹, [Ni²⁺]¹, and [H⁺]^?1. While the equilibrium constants favor Ni(LIX 65N)₂, the relatively large rate of reaction of the neutral LIX 63 leads to a catalysis of the overall LIX 65N extraction.     

Copper(II) Extraction from Phosphoric Acid Media by 5‐Dodecylsalicylaldoxime (LIX 622)

Abstract

The extraction of Cu(II) from phosphoric acid media (0.4–7.3 M) by the commercial reagent LIX 622 in toluene has been studied. Experimental results have been treated numerically and the formation in the organic phase of the complex CuR₂, HR being 5‐dodecylsalicylaldoxime, has been proposed. Values of the conditional extraction constants, which increase with the phosphoric acid concentration, are given. Organic extracts have been analyzed by EPR spectroscopy. The presence of a square planar complex of Cu(II) has been deduced confirming the stoichiometry CuR₂.     

Selective removal of copper ions from aqueous solutions using modified silica beads impregnated with LIX 84

Silica beads immobilized with 2‐hydroxy‐5‐nonylacetophenoneoxime (LIX 84) were prepared after silica surface modification by γ‐aminopropyltriethoxysilane (SB‐L). Batch and packed‐column tests were conducted to evaluate the metal ion removal capabilities of the prepared adsorbent. Equilibrium isotherms of the SB‐L with aqueous solutions containing copper ions were obtained. In addition, the kinetic performances for copper ion removal from aqueous solutions were investigated. The results showed that the amount of extraction increases with solution pH in the range between 1.5 and 5. The selectivity was also experimentally investigated, these results showed that the SB‐L adsorbed copper ions selectively in the presence of other metal ions such as Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Ca²⁺ and Mg²⁺. From the regeneration experiments, it was found that the copper ions adsorbed at the SB‐L surface were recovered by acidic solutions. The recovery ratios were between 78% and 90%, depending on the types of acidic solutions. The results showed that the SB‐L prepared may be used for the selective extraction of copper ions from aqueous solutions. © 1999 Society of Chemical Industry