LIX 84-I Research Articles

Highly efficient and eco-friendly process for selective recovery of copper from waste printed circuit boards via pyrolysis and ammoniacal solvoleaching

This study proposes a process combining pyrolysis and ammoniacal solvoleaching to selectively recover Cu from waste printed circuit boards (WPCBs). Optimal pyrolysis conditions were determined by investigating parameters such as temperature, heating rate, N2 flow rate, holding time and particle size. Under the conditions: 500 °C temperature, 20 °C/min heating rate, 0.3 L/min N2 flow rate, 10 min time and +9.50 mm particle size, ∼25% of weight loss was obtained. The pyrolyzed mass underwent further physical separation process involving impact crushing, magnetic- and gravity separations to enrich metals into a concentrate. Copper in the resulting concentrate was selectively extracted using a one-stage ammoniacal leaching and solvent extraction process (ammoniacal solvoleaching), employing an oxime-based organic extractant, LIX 84-I with a small volume of NH4OH. Ammoniacal solvoleaching was optimized by considering parameters such as stirring speed, time, LIX 84-I concentration, volume of aqueous ammonia, temperature and pulp density. Under the following conditions: 500 rpm, 0.3/0.3/10 (g/mL/mL) of sample/NH4OH/LIX 84-I (0.8 M), 3 h time and 25 °C temperature, quantitative Cu dissolution was achieved after two-stage solvoleaching. Cu solvoleaching followed the Avrami model, with an activation energy of 28.95 kJ/mol in the temperature range 15–45 °C (298–318 K) for the mixed control mechanism. LIX 84-I could be recycled without loss of extraction performance. Cu concentration was further enriched during stripping stage using H2SO4. A flowsheet for the sustainable metal recovery from WPCBs was developed.

Evaluating cationic extractant systems containing Versatic 10 on the solvent extraction of metals from an Ni lateritic sulfuric solution

The solvent extraction of Ni, Co, Cu, Ca, Mn, Mg, and Zn was evaluated in this work using Versatic 10 and its mixture with D2EHPA, Cyanex 272, Cyanex 301, LIX 84-I, and LIX 860N-IC. The aqueous phase reproduces a liquor obtained by applying a sulfation-roasting-leaching process in an Ni lateritic ore after precipitation of Fe, Al, and Cr. Tests were conducted at 40 °C, A/O ratio = 1, and [extractant] = 0.5 M. It was found that Cu, Ni, Co, Zn, and Mn can be separated from Ca and Mg by Versatic 10 at pH 6.5. Similarly, Cu, Zn, Co, and Ni can be separated from Mn, Ca, and Mg by Versatic 10 + Cyanex 301 at pH 1.5, whose antagonism on Mn extractions favors Co/Mn and Ni/Mn separation at pH 1–2. Synergism was verified on Ni extractions with Versatic 10 + LIX 84-I and Versatic 10 + LIX 860 N-IC systems. Cu, Ni, and Co are preferentially extracted over Zn, Mn, Ca, and Mg by Versatic 10 mixed with LIX 860 N-IC and LIX 84-I at pH 4 and 5, respectively. Stripping tests using Ni electrolyte solution (50 g/L Ni + 1 M H2SO4) from the loaded Versatic 10 + LIX 860 N-IC resulted in the recovery of 80% Ni, 70% Co, and 42% Cu. These four organic systems may have potential applications in direct SX operations. Conversely, Versatic 10 + D2EHPA and Versatic 10 + Cyanex 272 preferentially extract some impurities over Co and Ni. At pH 3, Zn, Ca, Cu, and Mn can be removed over Co and Ni using Versatic 10 + D2EHPA; synergism was found to Mn extractions. Versatic 10 + Cyanex 272 separated Zn, Cu, and Mn at pH 3.5 leaving Co, Ni, Ca, and Mg in the raffinate; synergism was found to Ca extractions. Targeting the extraction of impurities over Co and Ni, Versatic 10 + D2EHPA is superior to Versatic 10 + Cyanex 272, with potential application to treat liquors obtained from the dissolution of MHP.

Non-dispersive solvent extraction as an alternative for sulfuric acid and copper recycling from membrane distillation concentrate of gold mining wastewater

The wastewater from the pressure oxidation process is a complex stream enriched in sulfuric acid and dissolved metallic species, conventionally treated by neutralization, a technique that does not allow for by-product recovery. Previous studies focused on water recovery from the wastewater by membrane distillation and the concern related to concentrate production after water is recovered is now addressed by using hollow-fiber membrane contactors in non-dispersive solvent extraction processes intended for sulfuric acid and copper recycling. Tris(2-ethylhexyl)amine (TEHA), Aliquat 336, and Lix 84-I were used as extractants, the first two for acid recovery and the latter for copper. It was investigated the contribution of different organic phases flow rate (4–12 cm3/s), organic phase composition (5–15 wt%), and temperature (30–60 °C) on the performance of hollow fiber membrane contactors, with an in-depth disclosure of mass transfer phenomena limiting the extraction efficiency. For both acid and copper recovery, a reduction in viscosity forces prevails over the decrease in inertial forces, improving the flow regime. Even so, the predominant mechanism was the diffusive transport of both solutes into the fluid, across the membrane pores, rather than being carried along by the aqueous phase flow. The acid and copper recovery from membrane distillation concentrate achieved values greater than 91%, which represents an acid stream containing 5.86 g-H2SO4/L and an aqueous copper solution with a concentration of 269.0 mg/L, both at high purity. It was discussed different opportunities for their reuse within the gold ore processing circuit and challenges related to their external commercialization. Preliminary economic analysis suggested that the mineral acid would present slightly higher costs than currently practiced (0.54 US$/kgH2SO4; market prices: 0.03–0.11 US$/kgH2SO4), although the operational costs related to copper were comparable with market prices (11.58 US$/kgCu; market prices: 10.31 US$/kgCu). In a broad context, the opportunity for acid and sulfuric acid recycling has the potential to extend sustainability in the mining sector.

Polymeric Microcapsules as Robust Mimics of Emulsion Liquid Membranes for Selective Ion Separations.

Selective ion separations are increasingly needed to combat water scarcity, recover resources from wastewater, and enable the efficient recycling of electronics waste. Emulsion liquid membranes (ELMs) have received interest due to rapid kinetics, high selectivities, and low solvent requirements but are too unstable for industrial usage. We demonstrate that polymeric microcapsules can serve as robust, solvent-free mimics of ELMs. As a proof of concept, we incorporated the copper-selective ligand Lix 84-I in the walls of microcapsules formed from a commercial polystyrene-b-polybutadiene-b-polystyrene triblock polymer. The microcapsules were formed from a double-emulsion template, resulting in particles typically 20-120 μm in diameter that encapsulated even smaller droplets of a dilute (≤0.5 M) H2SO4 solution. Batch experiments demonstrated facilitated-transport behavior, with equilibrium reached in as little as 10 min for microcapsules with 1% ligand, and with ∼15-fold selectivity for Cu2+ over Ni2+. Furthermore, the microcapsules could be packed readily in columns for flow-through operation, thus enabling near-complete Cu2+ removal in ∼2 min under certain conditions, recovery of Cu2+ by flowing through fresh dilute H2SO4, and reuse for at least 10 cycles. The approach in this work can serve as a template for using selective ligands to enable robust and simple flow-through processes for a variety of selective ion separations.

Recovery of surface-plated metals from lead frame scrap using selective leaching and solvent extraction

The selective leaching of surface-plated metals from lead frame scrap followed by metal separation and enrichment through solvent extraction has been investigated. The leaching of lead frame scrap using H2SO4 solution under non-oxidizing and oxidizing conditions could efficiently and selectively dissolve Ni, leaving majority of Cu-substrate in the leach residue for further processing. The leaching carried out in a 1.0 M H2SO4 solution at 400 rpm agitation speed, 90 °C temperature and 15 g/L pulp density yielded a Ni leaching efficiency of 98.6% for 240 min (non-oxidative), but required only 60 min to reach the Ni efficiency of 96.4% while supplying 1.0 L/min O2 (oxidative). For both leaching systems, Cu dissolution was found to be <7% only without any dissolution of precious metals contained in the scrap. The kinetic study showed that the Ni leaching under non-oxidizing conditions proceeded by a single rate-controlling step following film diffusion model with activation energy of 12.6 kJ/mol in the temperature range 50–90 °C.The Ni leaching in oxidative system was however, controlled by a mixed control model comprising film diffusion and chemical reaction with the activation energy of 40.0 kJ/mol in the same temperature range. These results were corroborated by SEM analysis of the leach residue. Subsequently, leach liquor obtained from the oxidative leaching (0.84 g/L Cu2+ and 0.32 g/L Ni2+) was subjected to solvent extraction using LIX 84-I. Based on the extraction data, a two-stage counter-current extraction at A/O ratio = 10/1 was required using 20% LIX 84-I to quantitatively extract and enrich Cu2+ from the solutions (equilibrium pH 2.5). The stripping of Cu-loaded organic phase indicated that a three-stage counter-current stripping using 200 g/L H2SO4 at O/A ratio of 5/1 was required. Nickel(II) from the copper free aqueous solution was extracted and enriched using 20% LIX 84-I at an A/O ratio of 5/1, and was stripped from the loaded organic phase using 20 g/L H2SO4 at O/A ratio of 5/1. The hydrometallurgical route of selective leaching-SX results in not only Cu- and Ni-rich solutions suitable for recovery of final products, but also Ni-free lead frame scrap for further processing by smelting. Finally, a flowsheet has been proposed for the total recycling of lead frame scrap.

Membrane distillation and dispersive solvent extraction in a closed-loop process for water, sulfuric acid and copper recycling from gold mining wastewater

Membrane distillation (MD) and dispersive liquid–liquid extraction (d-LLE) were integrated for gold mining wastewater beneficiation and better use of natural resources. MD presented an average permeate flux of 5.51 ± 0.14 L/m2·h, without a significant flux decay (p < 0.001), and rejection efficiencies for acid and metallic species>98.7%. Five different extractants were studied for sulfuric acid recovery from MD concentrate. Considering the extraction and stripping efficiency, tris-2-ethylhexylamine (TEHA) was the most appropriate alternative for sulfuric acid extraction, requiring 2 stages of extraction and 1 of striping to achieve a recovery>95%. The endothermic nature of acid extraction contributed to the integration of d-LLE and MD, designating a proper destination for MD concentrate, a stream often forgotten while discussing membrane separation processes for wastewater treatment. Copper was then selectively recovered from the raffinate from acid extraction (βCu/Fe = 4,274, βCu/Al = 176, and βCu/Mg = 1,262) by Lix 84-I. A single contact stage ensured that 99.3% of copper was recovered. Fourier-transform infrared spectra demonstrated that the acid extraction mechanisms involve amine salts formation, whereas copper is extracted by anion exchange processes. The economic assessment was favorable for water (US$/m3 0.23) and copper (US$/kgCu 4.25) recovery, with prices lower than currently practiced for both commodities. For sulfuric acid, the operational expenditures corresponded to US$/kgH2SO4 0.423, slightly higher than its marketable price. Overall, the integrated system could be inserted in a perspective that departs from the linear focus of raw material utilization, prioritizing recycling and reuse processes.

Study on hydrometallurgical recovery of copper and rhenium in processing of substandard copper concentrates

Over the past decade, there has been a steady growth in demand for rare metals, with rhenium being one of the most highly demanded, but also one of the most expensive and difficult to obtain. The high demand for rhenium is due to its use as a key component of metallurgical alloys or as a component of catalysts used in the oil refining industry. The aggregate of facts causes profitability of processing of the rhenium-containing mineral resources, which also are the copper substandard concentrates obtained at processing of the Zhezkazgan sandstones. The study focuses on the processes of extraction of copper and sorption recovery of rhenium from solutions of ammonia leaching of copper substandard concentrates. Model solutions similar in the elemental composition to solutions of ammonia leaching solutions of copper substandard concentrates obtained during the processing of Zhezkazgan sandstones were used as an object of the study. The paper estimates extraction characteristics of copper recovery using LIX 84-I solution in kerosene, as well as sorption characteristics of the rhenium recovery process using the Purolite PPA100 anion exchanger. Based on the obtained characteristics the possibility of hydrometallurgical processing of ammonia leaching solutions of substandard copper-sulfide concentrates, and recovery of the obtained commercial products is shown.

Sustainable treatment of bimetallic (Ag–Pd/α-Al2O3) catalyst waste from naptha cracking process: An innovative waste-to-value recycling of precious metals

Bimetallic (Ag–Pd/α-Al2O3) catalysts are essentially applied to naptha-cracking process with a controlled CO2 emission. After losing the catalytic properties in long run, the landfilling disposal of spent catalysts poses severe stress to the environment and deprivation of precious metals. Therefore, an innovative solvo-chemical recycling approach that involving the solid-liquid and liquid-liquid mass transfer phenomena was studied. The parametric variations for dissolving precious metals yielded >98% efficiency at a lixiviant concentration, 2.0 mol L−1 HCl; pulp density, 20% (wt./vol.); agitation speed, 300 rpm, temperature, 90 °C, and duration, 60 min. The activation energy of silver (6.9 kJ mol−1) and palladium (11.9 kJ mol−1) leaching indicated that the process was governed by a diffusion-controlled mechanism. Subsequently, silver and palladium were separated using 0.15 mol L−1 LIX 84-I at different acid concentration that yielding the maximum separation factor (β(Ag/Pd) = 12,501) at 2.0 mol L−1 HCl. Stripping of separately (Ag/Pd)-loaded organic solutions with different solutions of HNO3, (NH4)2SO4, and CH4N2S showed higher affinity for thiourea, yielding 56%, 38%, and 87% efficiency, respectively. Thus the counter-current extraction at an organic-to-aqueous (O:A) ratio of 1:2.5 and stripping with 0.5 mol L−1 CH4N2S at an O:A ratio of 2:1 yielded a five-fold enrich solutions of precious metals (75.2 mg L−1 Ag and 188.5 mg L−1 Pd) with a purity of >99.9%. The process essentially aims to Goal 12 under the United Nations’ Sustainable Development Goals for sustainable recycling of industrial wastes consequently conserving the natural mineral reserves.

Process Flowsheet Development for Separation of Sm, Co, Cu, and Fe from Magnet Scrap.

A complete process flowsheet to recover metal values from Sm2Co17-type magnet scrap was investigated. The magnet scrap was leached in chloride medium at pulp density of 2% (w/v) under the optimum conditions of 15% (v/v) HCl and 5% (v/v) H2O2 at 70 °C for 3 h, which yielded 98.5% Sm and 99% Co extractions. The full factorial Design of Experiment technique was adopted for the optimization of leaching conditions. Sm was selectively separated from the leach liquor as precipitated double salt using Na2SO4. The precipitated double sulfate was later converted to Sm-oxalate, which was subsequently calcined to produce pure Sm2O3. Following Sm separation, Fe was removed through precipitation by raising the pH to 3.0. For Cu and Co recovery, solvent extraction techniques using LIX 84I and Na-CYANEX 272, respectively, were followed. The McCabe–Thiele diagrams for extraction as well as stripping were presented for both Cu and Co.

Simple and complete separation of copper from nickel in the ammoniacal leach solutions of metal coated ABS plastic waste by antagonistic extraction using a mixture of LIX 84-I and TBP

A solvent extraction-based method using mixed extractants of LIX 84-I and TBP has been developed for complete separation of copper from nickel in the ammoniacal leach solutions of ABS plastic waste. The selective separation of copper was facilitated by the antagonistic effect of the extractants on depressing nickel extraction. The FTIR spectra indicated the possibility of hydrogen bonding between H-atom of hydroxyl group of LIX 84-I and O-atom of phosphoryl group of TBP while lowering the availability of extraction sites of LIX 84-I and increasing the bulky alkyl groups in the organic phase, causing the antagonism desired for Ni extraction. A McCabe-Thiele diagram of copper exhibited that a four counter-current stage at operational conditions of 0.5 M LIX 84-I + 0.5 M TBP, aqueous/organic (A/O) phase ratio of 1.3/1 and 25 °C was required to achieve the quantitative selective extraction of copper from real solution of ABS plastic waste with Cu2+ and Ni2+ concentration of 8.14 and 2.57 g/L, respectively, without any coextraction of nickel to the organic phase. Complete stripping and enrichment of copper was reached after a three counter-current stage using 2.0 M H2SO4 solution at O/A phase ratio of 2/1; copper in the stripped solution was found to be 21.03 g/L. Recycling of the mixed extractants for reuse in copper and nickel separation was demonstrated, and thereafter, a recommended flowsheet of recycling metals from ABS plastic waste was given. The antagonistic extraction system comprising of oxime-based extractant, LIX 84-I, and organophosporus extractant, TBP, presented in this study shows a potential for sustainable metal separation process.

Role of ethanol on particle size and morphology during copper oxalate synthesis by Precipitation-Stripping

Copper oxalate particles were synthesized from a copper loaded oil phase using the precipitation-stripping (PS) technique with oxalic acid as the stripping and precipitating agent. The copper source was a spent ammoniacal printed circuit board etch solution and LIX 84I was the metal extractant. The role of ethanol in stripping solution on stripping rates, particle morphology and size was investigated. An increase in ethanol concentration enhanced both rate and extent of stripping. PS with aqueous oxalic acid resulted in cushion shaped particles with a wide size distribution which changed to flat discs with an increase in precipitation time. Changes in the polarity, dielectric strength, coupled with significant reduction in the interfacial tension between oil and aqueous phases due to the presence of ethanol in the stripping solution resulted in spherical submicron particles with a narrow size distribution. This investigation paves way for a process to synthesize submicron oxalate particles.

Extraction of nickel and cobalt from a laterite ore using the carbothermic reduction roasting-ammoniacal leaching process

The carbothermic reduction roasting followed by ammoniacal leaching of a Ni-laterite ore from Bajaur (Pakistan) has been studied first time for its potential exploitation via the Caron process. The use of fuel oil as reductant can be costly in Pakistan, therefore, plenty available coal was employed in this study. The roasting parameters like coal mixing proportion (5–15 wt%), temperature (600–900 °C), additive dosage (3–12 wt%), and time (15–180 min) were varied to optimize the selective reduction of Ni and Co. The extent of goethite phase transformation of roasted products characterized through the X-ray diffraction (XRD) analysis could depict sharp peaks for the formation of Ni-Fe alloy phase in the presence of an additive, Na2SO4. The optimal reduction condition was observed to be laterite ore mix with 10 wt% coal and 9 wt% Na2SO4, and roasted at 800 °C for 120 min. Leaching of the roast-reduced product performed in NH4OH–(NH4)2CO3 solutions (150 g/L total NH3) was influenced by carbonate ion concentration and yielded >90% Ni and 67% Co. The apparent activation energy of Ni, 21.2 kJ/mole and Co, 7.6 kJ/mole indicated to follow intermediate-controlled and diffusion-controlled mechanism, respectively. Furthermore, the leach liquor was pre-oxidized and contacted to 10 vol% of LIX 84-I; yielding a selective extraction of >97% Ni over Co at the organic-to-aqueous ratio of 1. Results presented in this paper suggest that the extraction of Ni and Co from Bajaur lateritic ore is technically feasible through the Caron process, and can be useful to others as well.

Investigation of the factors affecting oil agglomeration using different reagent mixtures as a bridging liquid

ABSTRACT In this study, the effects of some process parameters on oil agglomeration performance of lignite were investigated using different reagent mixtures as bridging liquids. The organic solvent extraction reagents (with trade names of Dehpa, LIX 84-I, LIX 984 NC) and classical bridging liquids (kerosene, diesel oil, fuel oil no.4) and their mixtures at different ratios were used as bridging liquids. The effects of bridging liquid type and concentration, solid ratio and agglomeration time were investigated and the results were analyzed on terms of yield, combustible recovery, and ash value. The optimum conditions were obtained using a mixture of 60% of fuel oil no.4 + 40% of diesel oil (wt.%), at a liquid concentration of 20% (wt.%), a solid ratio of 2% (wt.%) and an agglomeration time of 20-min. Under these conditions the maximum yield, combustible recovery, and minimum ash were achieved and were 70.22%, 77.65% and 9.99%, respectively.

Hydrometallurgical recycling of surface-coated metals from automobile-discarded ABS plastic waste

The ammoniacal leaching of surface-coated metals from automobile-discarded ABS plastics followed by their recovery through solvent extraction has been investigated. The leaching of ABS (typically containing 4.1% Cu, 1.3% Ni, and 0.03% Cr) could efficiently dissolve the ammine complexes of Cu and Ni, leaving Cr unleached as fine particles. The optimization studies for achieving the maximum efficiency revealed that the leaching of metal ions in different ammoniacal solutions follows the order CO32− > Cl− > SO42−. The leaching carried out in a carbonate medium by maintaining the total NH3 concentration 5.0 M at a NH4OH/(NH4)2CO3 ratio of 4:1, pulp density of 200 g/L, agitation speed of 400 rpm, temperature of 20 °C, and time of 120 min yielded the optimum efficiency of >99% Cu and Ni (i.e., 8.14 g/L and 2.57 g/L, respectively, in the leach liquor). Subsequently, the solvent extraction of metals from ammoniacal leach liquor as a function of extractant (LIX 84-I) concentration and organic-to-aqueous (O:A) phase ratio was examined. Based on the extraction data, a three-stage counter-current extraction at O:A = 1:1 was validated using 0.8 M LIX 84-I, yielding the quantitative extraction of both metals into the organic phase. Thereafter, the stripping of metals in acid solutions indicated that 0.5 M H2SO4 could quantitatively strip Ni from the loaded organic phase; however, ∼27% Cu was also co-stripped. The rest of Cu from the Ni-depleted organic phase was separately stripped with 1.0 M H2SO4 that can be directly sent to the electrowinning process. On the other hand, the co-stripped metals from the acidic solution can be easily separated, again using LIX 84-I as the extractant, by adopting the pH-swing method. Finally, a process has been proposed for the hydrometallurgical recovery of surface-coated metals from waste ABS plastics; that does not affect the physicochemical characteristics of the polymer substances for their reuse.

The Effects of a Novel Bridging Liquid Mixtures on Lignite Enrichment Using the Oil Agglomeration Process

ABSTRACTThis study investigated enrichment of lignite coal with oil agglomeration by using the mixtures of different bridging liquids. In oil agglomeration, the effects of many processing parameters such as the bridging liquid type and concentration, solid ratio and agglomeration time were investigated. The most suitable oil agglomeration conditions were determined to be a mixture of 40% of LIX 84-I + 60% of kerosene (wt.%) as a bridging liquid, 20% (wt.%) of bridging liquid concentration, solid ratio of 3.6% (wt.%) and 15 minutes of agglomeration time. Using these optimum conditions, the ash content of lignite was reduced from 49.60% to 10.33%, at a yield and combustible recovery of 32.80% and 58.36%, respectively.

Reclamation of copper from spent ammoniacal Printed Circuit Board (PCB) etch solutions

Ammoniacal spent etch liquors is a potential source for copper recovery. In the present investigation copper was extracted from spent ammoniacal PCB etch solutions using hydroxyoxime LIX 84I. Maximum extraction was observed at equilibrium pH of 8.9. Three counter-current stages were required for quantitative extraction of 51.8 g/L copper from the spent liquor using 50%v/v extractant at an O/A ratio of 1.5. It was also possible to achieve quantitative extraction with 20% v/v extractant concentration at an equilibrium pH of 8.9 and O/A ratio 4.5:1. Precipitation −stripping of the loaded organic phase using oxalic acid led to reclamation of copper as copper oxalate. Contacting the oil phase fully loaded with copper in 50% v/v extractant, with 1 M oxalic acid at equal O/A resulted in 77.4% copper getting stripped in first contact, quantitative stripping was achieved in the second contact with fresh acid. There was a close agreement between the experimental and predicted yields based on solubility plots developed for copper-oxalic acid system. Co-extracted ammonia to the organic phase was stripped as soluble ammonium oxalate offering an inherent advantage over the conventional stripping process where build-up of ammonium sulphate is observed during electrowinning process. Calcinations for three hours formed copper oxide, XRD and chemical analysis confirmed the formation of pure copper oxide. The copper present in waste etchant could thus be appropriately converted to value added product.

Solvent extraction of praseodymium using different extractants – a synergistic study

ABSTRACTThe 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.

Extraction-Stripping Patterns during Co-Extraction of Copper and Nickel from Ammoniacal Solutions into Emulsion Liquid Membranes Using LIX 84I®

Extraction of nickel and its co-extraction with copper from ammoniacal media into emulsion liquid membrane systems (ELMs) was investigated using LIX 84I as the carrier. Measurement of the solute stripped in the internal phase of emulsion opened a new dimension in the study of the ELM extraction processes. The effect of operating parameters such as feed pH, initial feed concentration, and treat ratio of emulsion to feed and the effect of emulsion parameters such as internal phase stripping acid concentration, carrier concentration, and internal phase volume fraction were investigated. The optimal pH for extraction was 8.1. The overall extraction process was strongly favored by the factors that lead to enhancement of uptake of metal ions such as increase in the carrier concentration and the treat ratio. Investigations on the stripping patterns in W/O emulsions revealed that sulfuric acid of 1.0 M concentration was optimal for nickel stripping in ELMs but the process was slow. Stripping of copper was relatively fast and was favored by higher acid concentrations. The amount of nickel extracted declined in the presence of copper during co-extraction of copper and nickel and the amount of copper stripped in the internal phase of the emulsion was equivalent to the amount of nickel loaded by the emulsion. In general, almost 55% of the metal loaded in the emulsion was found to get stripped in the duration of the runs. Hence, there is scope to formulate emulsions and tune other operating parameters to achieve selective separation of one of the two metals co-extracted in the internal phase of the emulsion.

A conceptual process for copper extraction from chalcopyrite in alkaline glycinate solutions

A conceptual flowsheet is proposed and the main processing steps are evaluated for the alkaline processing of chalcopyrite where glycine is the complexing agent. Glycine is utilised in an oxidising, alkaline environment to leach chalcopyrite at atmospheric pressure and mildly elevated temperatures. Process steps to recover copper and glycine from alkaline aqueous solutions were also investigated. The leaching of chalcopyrite flotation concentrate in glycine solutions was conducted at different leach conditions in a 1.25L leach reactor with an agitated slurry and controlled dissolved oxygen (DO) concentration. In the presence of air, oxygen or hydrogen peroxide or a mixture thereof, glycine can dissolve copper from chalcopyrite at either ambient or elevated (40–60°C) temperatures and atmospheric pressure. Increasing temperature, pH, glycine concentration and DO concentration all increase the rate and extent of copper extraction. The extraction of copper from “as-received” chalcopyrite flotation concentrate, at a particle size of 100% −45μm, in solutions containing 0.4M glycine at 60°C with 25ppm DO, was 40.1% after 24h. If the chalcopyrite concentrate underwent an ultrafine grind to100% −10μm with prior alkaline atmospheric pre-oxidation, 92% of the copper is leached within 17 h at 60°C, atmospheric pressure and 9% solids during a batch leach. Pyrite associated with the chalcopyrite remained unreacted during leaching of chalcopyrite and iron concentration in the final pregnant solution was found to be less than 20mg/L. Copper recovery by sulfide precipitation from the leach solution as pure covelite was up to 99.1% at a Cu:S2− molar ratio of 1:1. Solvent extraction (SX) experiments with LIX 84-I demonstrated that copper can be extracted into the organic phase up to 99.4% in a single stage at an equilibrium pH range 8.8–10.0. It is shown that copper can be stripped from the organic phase in a single stage acidic strip using conventional acidic return electrolyte containing 180g/L sulfuric acid. During copper recovery by precipitation as sulfide, or by solvent extraction, the glycine is made available for recycling and reuse as a barren leach solution, after treatment with lime.

Selective transport and simultaneous separation of Cu(II), Zn(II) and Mg(II) using a dual polymer inclusion membrane system

A dual polymer inclusion membrane (PIM) system is proposed for the simultaneous separation and enrichment of Cu(II), Zn(II) and Mg(II). PIMs containing 2-hydroxy-5-nonylacetophenone oxime (LIX 84I) and di(2-ethylhexyl) phosphoric acid (D2EHPA) as carriers were prepared in order to separate Cu(II) and Zn(II) from solutions containing multiple cations. The transport results indicate that the simultaneous separation of the three metal ions is highly dependent on the feed pH. At pH 2, Zn(II) and Cu(II) can be selectively transported into the respective stripping solutions, leaving Mg(II) in the raffinate. The dynamic transport model was established and confirms that the kinetic reaction rate is the controlling factor in the transport and separation of the metal ions. XPS and IR spectral analyses were carried out to elucidate the membrane extraction mechanism. As a novel application of the PIMs, the stability and uphill effect of the dual PIM system were also tested and has been compared with the performances of liquid membrane systems.