Leach Liquor Research Articles

Stepwise recovery of cerium and fluorine from bastnaesite: Utilizing complex properties of B-F to obtain high purity CeO2 and KBF4

This research investigates a new approach for recovering fluorine and cerium from a boric-acid-added bastnaesite sulfuric leaching liquor by Cyannex923. Systematic research of the effects of H3BO3 on bastnaesite leaching, extraction and stripping process was studied. The process mechanism and conditions in each step, including concentrations, proper pH, K/B and B/F ratio and temperature, were also determined. The result describes that that the formation of B-F complex improves the extraction of Ce and F. The formation of B-F complex also provides a new method to realize the separation and stepwise recovery of Ce and F. After Ce, B and F were co-extracted, Ce/B-F loaded organic phase are stepwise stripped by H2SO4 + H2O2 and NH3·H2O, allowing recovery of KBF4 with 97.12 % purity and CeO2 with 99.95 % purity from stripping solutions. The size distribution and SEM images of KBF4 product were given as well, which showed KBF4 was mainly 1 μm particles and dispersed well. Furthermore, the whole process based on the mechanism was designed and confirmed by cascade extraction test.

A roast-leach process for the recovery of vanadium from vanadium-bearing gasifier slag (VBGS) using citric acid as a green reagent: Leaching studies and statistical analysis for sustainable processing

The vanadium-bearing gasifier slag (VBGS) generated by petroleum industry as solid waste is considered as one of the valuable vanadium-containing resources. So, recovery of vanadium from VBGS is important from the environmental and industrial points of view. This work investigates vanadium leaching from VBGS at atmospheric pressure using a green reagent and achieves comprehensive utilization of the slag. Citric acid, an eco-friendly leachant, was used to recover V. Different leaching parameters were optimized and the maximum vanadium recovery of 98.8% was achieved at the optimum leaching condition of pH 1.5–1.7, temperature 75 °C, citric acid concentration 2.5%, pulp density 10% and leaching time 30 min. The leaching of vanadium showed that there were two stages in the kinetics of leaching. In the first 30 min, a sharp increase in the amount of vanadium extracted was observed and at longer times, leaching rate decreased. The blue colour of the leach liquor (LL) indicated that vanadium was leached in the form of V4+. The experimental data were employed as an input to the response surface methodology (RSM) to determine the best dependent/independent variables and predicted optimum condition to obtain maximum leaching efficiency. Finally, the present process results in the utilization of industrial waste to recover valuable metal ion and minimization of vanadium bearing primary resources.

Adsorptive removal of Uranium (VI) using zeolitic imidazole framework (ZIF)-67 from alkaline leach liquor

As the applications of nuclear technology diversify, development of adsorbents with superior selectivity and adsorption capacity for the removal of Uranium (U) from aqueous stream becomes imperative. In this article, zeolitic imidazolate framework-67 (ZIF-67) is used to examine the removal of U from simulated and actual alkaline leach liquor. The influence of pH and adsorbent dose were also analyzed. The synthesized ZIF-67 reveals a significant amount of U uptake capacity (396 mg g−1) and remarkable removal percentage for U in both synthetic and alkaline leach liquor (>98 % and 97.4 %, respectively). Based on various characterization techniques, a detailed U adsorption mechanism was established. The alkaline leach liquor was comprehensively characterized and different parameters (both before and after U adsorption) were determined. The ZIF-67 adsorbent showed satisfactory regeneration performance and structural integrity, with>80 % U removal after 5th regeneration cycle. For the purpose of forecasting the adsorption kinetics and related mass transfer parameters, a first principle based pore diffusion-adsorption model was used.

One-step extraction and solidification of uranium (VI) from sulfate leaching liquor using bifunctional ionic liquids

Three bifunctional [DODMA]+[DGA]- ionic liquids were synthesized starting from [DODMA]+[Cl]- surfactant and N, N-dialkyl-diglycolamide acid (DGA), which were employed for extraction of U(VI) from real leach solution. The simultaneous purification and solidification of uranium (VI) were realized in one-step process in sulfuric acid medium, and the extracted solid captured more than 99 % uranium (VI) was found to aggregate at the biphasic interface. XPS, FT-IR, ESI-MS and TGA analysis revealed that U(VI) ions were assembled into uranium-containing solids by coordination of uranyl ions and dicarbonyl groups of [DGA]- anions using amphiphilic property of [DODMA]+ cations. An unusual multi-step extraction mechanism by anionic exchange was proposed to elucidate the excellent selectivity for U(VI). The present bifunctional ionic liquids exhibited the high affinity for U(VI) compared to 18 main elements assayed in ore leaching liquor. The key interfering ions such as Fe(III) and V(V) were hardly extracted to enrich in the extracted solid, and the good separation factors were obtained in 280 for U/Fe and 117 for U/V. Without further back-extraction, final precipitation and other relevant operation, the proposed one-step strategy was considered as a sustainable or promising process for easier recovery of U(VI) in sulfate leaching liquor.

Synthesis and characterization of nano sodium vanadate rods from fly ash produced from heavy oil-fired electrical power stations

In the current study, an original, economic, and eco-friendly technique was used in the preparation of sodium vanadate nanorods from the leach liquor of fly ash. Most researchers recover vanadium oxide from fly ash rather than nano vanadium, and they also synthesized nano sodium vanadate by a hydrothermal method consuming high energy. Selective precipitation method using sodium carbonate was used in the preparation of sodium vanadate nanorods. The optimum conditions for the leaching process are temperature, time, L/S, and sodium carbonate amount. 70 °C, 60 min, 10/1, and 130 g/l, respectively. Under these conditions, approximately 80% of the vanadium in fly ash was leached. Sodium vanadate nanorod synthesis gives the best yield and purity of the final product by a simple process. Using X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transform Infrared (FTIR), and Dynamic Light Scattering (DLS), the synthesized NaV6O15 nano rods have been characterized.

Recycling of NdFeB magnets employing oxidation, selective leaching, and iron precipitation in an autoclave.

The increasing production of neodymium-iron-boron (NdFeB) magnets for technological applications results in disposal problems. NdFeB magnets contain a significant quantity of rare earth elements (REEs). China is the largest REEs producer, but it applies quotas and increases the export prices of REEs. To address this issue, this study aims at investigating the recovery process of REEs from scrap NdFeB magnets. After oxidation of NdFeB magnet powders, selective leaching with nitric acid was carried out to achieve high-purity REE-rich leaching liquor. First, the oxidation kinetics of NdFeB powders was studied in detail to determine the oxidation temperature and duration. Afterwards, the effects of selective leaching parameters, including acid concentration, leaching temperature, stirring speed and solid/liquid ratio, were examined by analysis of variance (ANOVA) analysis based on Taguchi method. The most substantial parameters were assigned to be the temperature and solid/liquid ratio. Eventually, the dissolution kinetics were studied to propose a model for REEs. Several universal equations for dissolution kinetics were tested, and (1 - (1 - x) = k × tn) gives the best results for REEs. The findings show that the leaching process follows the shrinking core model. Activation energy was calculated to be 40.375 kJ mol-1 for REEs. As the last step, the iron dissolved during leaching was precipitated as hematite in the autoclave. The hematite precipitation experiments were performed based on the Box-Behnken design. The effect of precipitation parameters was investigated by ANOVA analysis, and the precipitation process was optimized using response surface methodology (RSM), which resulted in the minimum iron and maximum REEs content in the leach liquor.

Evaluation of acid mine drainage (AMD) from tailings and their valorization by copper recovery

Recent investigations have found that the mining industry generates approximately 10 billion tons of tailings per year, tending towards doubling this amount by 2035. For this reason, a systematic method is needed to study acid mine drainage (AMD) potential, as well as determining the dissolution of potentially toxic elements (PTEs). Furthermore, the possible recovery of base or precious metals could transform the tailings into value-added materials. In the present investigation, the potential for the generation of acid mine drainage in a sample of mine tailings was evaluated, as well as an analysis of the dissolution of PTEs through a sequential extraction of appropriate chemical solutions with increasing strength of reactivity to identify base or precious metals that can be recovered through a metallurgical process consisting of leaching, solvent extraction and electrolysis, operating at moderate pressure and temperature. The results of this research showed that these tailings contain approximately 3.7% of pyrite occluded in silicates and therefore are not a high risk for generating acid drainage and PTEs dissolution. On the other hand, a process for obtaining metallic copper was proposed, which resulted in a leaching liquor with 1226 ppm using 0.21 M H2SO4 and a pulp density of 300 g/L. Solvent extraction in a single stage allowed the leach liquor to be concentrated at 9200 mg Cu/L, recovering the majority of the copper in metallic form by electrolysis.

Leaching of rare earths from Abu Tartur (Egypt) phosphate rock with phosphoric acid

The leaching of rare earth elements (REEs) from Egyptian Abu Tartur phosphate rock using phosphoric acid has been examined and was subsequently optimized to better understand if such an approach could be industrially feasible. Preliminary experiments were performed to properly define the design of experiments. Afterward, 24 full factorial design was implemented to optimize the leaching process. Optimum REEs leaching efficiency (96.7 ± 0.9%) was reached with the following conditions: phosphoric acid concentration of 30 wt.-% P2O5, liquid/solid ratio, mL/g, of 5:1, at 20 °C, and 120 min of leaching time. The apparent activation energy of the dissolution of REEs from phosphate rock using the phosphoric acid solution was -19.6 kJ/mol. D2EHPA was subsequently applied as an organic solvent for REEs separation from the acquired leach liquor. REEs stripping and precipitation were conducted, and finally, rare earth oxides with a purity of 88.4% were obtained. The leach liquor was further treated with concentrated sulfuric acid to recover the used phosphoric acid and produce gypsum with a purity of >95% at the same time. A flow diagram for this innovative cleaner production process was developed, and larger-scale experiments are proposed to further understand this promising approach to comprehensive phosphate rock processing.

Decellularized tilapia fish skin: A novel candidate for tendon tissue engineering.

The poor regenerative ability of injured tendon tissues remains a clinical challenge. However, decellularized extracellular matrix (ECM) combined with stem cells shows promise. In contrast to bovine and porcine ECM, marine-derived decellularized ECM has several advantages; it is easily obtained, poses less biological risk, and is not contraindicated on religious grounds. This study successfully fabricated decellularized tilapia fish skin (DTFS) with copious preserved collagen fibers and natural pore structures. The outer layer is smooth and dense, while the inner layer has a soft structure with a rough surface. After crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), crosslinked DTFS (C-DTFS) showed improved mechanics in dry and wet conditions. In vitro, the leach liquor of crosslinked DTFS showed no cytotoxicity and promoted migration and tenonic differentiation of tendon-derived stem cells (TDSCs). Meanwhile, TDSCs seeded in the inner surface of DTFS maintained viability, differentiated, and exhibited spreading. Furthermore, cell-seeded scaffolds guided the regeneration of tendon tissue in a rat Achilles tendon defect model. Our results suggest that DTFS combined with TDSCs is a novel and promising therapeutic option for tendon tissue engineering.

Ecological treatment of El Kriymat boiler ash for recovering vanadium, nickel and zinc from sulfate leach liquor

The primary goal of this work is to develop a technology that allows for the recovery of metal values from waste products, thereby promoting the wise and efficient use of our nation's resources. To achieve this goal, an industrial waste of El Kriymat boiler fly Ash was used for recovering its content of vanadium, nickel and zinc. About 97, 95 and 99% respectively of these economic elements were first dissolved from boiler fly ash magnetic concentrate (after physical concentration). Leaching experiments using optimum conditions include: 180 g/L sulfuric acid concentration and 4% solid/solid proportion manganese dioxide acts as an oxidant at 80 °C. The recovery of vanadium (V) metal ions was carried out using 3% Alamine 336 in kerosene at an equilibrium pH value of 0.9. Subsequently, 15% sodium sulfide solution was used for co-precipitation of nickel and zinc metal ions in the raffinate solution at pH value of 3.5.Graphical

Release-type bacteriostasis of Cu-bearing stainless steel against planktonic bacteria served in liquid system

Cu-bearing stainless steel (SS) with excellent broad-spectrum antibacterial property while maintaining the original mechanical properties of SS may quite be a more advantageous substitute for ordinary SS. Compared with its performance of directly inactivating the attached bacteria, the ability of Cu-bearing SS to kill planktonic bacteria for the applications in liquid system is still challenging ambiguous. Therefore, in this study, a corrosive medium containing chloride ions was applied to investigate that the service of SS in a liquid environment, such as water treatment system. The ions release behavior, release-type bacteriostasis against planktonic bacteria and the evolution of corrosion resistance for Cu-bearing 304L SS were investigated. Electrochemical test combined with X-ray photoelectron spectroscopy measurement proved that the passive film on 304L-Cu SS exhibited a significant game behavior including dissolution and repair processes, which eventually tends to be stable, ensuring the corrosion resistance in service. Compared with the artificial configuration solution with the same concentration of Cu ions, the antibacterial test confirmed that a better antibacterial performance against planktonic bacteria of the leach liquors derived from 304L-Cu SS. In particular, reactive oxygen species overexpression induced by the synergistic effect of multiple metal ions acted a crucial part in clarifying the relevant mechanism of bacteriostasis.

Recovery of cobalt as mesoporous Co3O4 from ammonia leaching solution of spent lithium battery cathode material via reductive ammonia distillation and thermal decomposition

Ammoniacal leaching system is widely applied to cobalt extraction due to its selectivity and mild leaching conditions. However, in ammonia leach liquor, the complexation of Co3+ and ammonia is stable (K[Co(NH3)63+] = 4.5 × 1033), which brings difficulties to cobalt recovery. In this work, a clean and sustainable process for recovering Co3+ as mesoporous Co3O4 product was proposed from NH3(NH4)2CO3 system, which included reductive ammonia distillation and thermal decomposition. Firstly, through ammonia distillation with simultaneous addition of hydrazine hydrate as a reducing agent, more than 97 % of cobalt can be precipitated in the form of (NH4)1.89Co7.88(CO3)6(OH)6(H2O)4.27 under the optimal conditions. Mechanism analysis shows that the addition of hydrazine hydrate can reduce part of Co3+ to Co2+, which is beneficial to the precipitation of cobalt. Subsequently, the Co3O4 products were prepared at 300 °C for 3 h via thermal decomposition of the precipitation. Meanwhile, the phase transformation and morphology changes of the product were investigated in-depth via relevant characterization methods. This process not only achieves efficient recovery of cobalt from the ammoniacal solutions but also the evaporated ammonia and residual solution can be returned to ammonia leaching.

Effects of Organic Acid Root Exudates of Malus hupehensis Rehd. Derived from Soil and Root Leaching Liquor from Orchards with Apple Replant Disease.

Organic acids secreted by plants, such as p-hydroxybenzoic acid, ferulic acid, cinnamic acid, and benzoic acid, can inhibit seed germination and root growth. The effects of root and soil leaching liquor from orchards on the growth of M. hupehensis Rehd. seedlings under sand culture are studied; the seedlings are sampled at 15, 30, 45, and 60 d. Changes in the amount of root exudates are determined using HPLC. Low concentrations of root leaching liquor (A1) and soil leaching liquor (B1) significantly promoted plant growth and chlorophyll synthesis; high concentrations of root leaching liquor (A6) and soil leaching liquor (B4-6) inhibited growth. Low concentrations of soil leaching liquor had no significant effect on the POD, SOD, and CAT activities. A5-6 and B5-6 significantly decreased Fv/Fm and qP values, respectively, and increased NPQ values. All root and soil leaching liquor treatments inhibited the secretion of gallic acid, hydroxybenzoic acid, benzoic acid, and phloridzin, and promoted the secretion of caffeic acid. The root leaching liquor treatments inhibited the secretion of catechin and promoted the secretion of phloretin. The soil leaching liquor treatments promoted the secretion of cinnamic acid. The secretion of other phenolic acids is likely associated with the different concentrations of leaching liquor.

Extraction of tungsten and molybdenum from waste alloy assisted by a recyclable roasting additive: β-MnO2

Extraction of molybdenum (Mo) and tungsten (W) from waste alloy significantly impacts the alleviation of resource shortage and ecological environment. In this study, Mn additive was utilized as a recyclable roasting aid to convert Mo and W for facilitating extraction, by considering thermodynamic calculations. The effect of β-MnO2 as a roasting additive on the phase evolution of Mo, W, and Mn elements and the optimal process conditions were evaluated by XRD, SEM-EDS, thermal analysis, and alkali leaching experiments. Notably, Mo and W in the alloy waste got oxidized and converted into soluble MnMoO4 and MnWO4, respectively, under the conditions of roasting temperature of 750 °C, β-MnO2 amount of 75% of waste alloy mass, and time of 1 h. During alkaline leaching, 100.00% Mo and 99.59% W in the roasted product were extracted, which was accompanied with the precipitation of leached residue of α-MnO2, Mn3O4, and Mn2O3 from Mn present in the leach liquor (NaOH concentration 2 mol⋅L−1, solid–liquid ratio 10% (w/v), time 5 h, temperature 90 °C). When the recycled leached residue was employed in the next roasting process, the leaching efficiency of Mo and W was maintained above 98.56%. Moreover, the reaction mechanisms of roasting and leaching were investigated by kinetics study. Roasting with β-MnO2 fundamentally reduced the production cost with the high extraction efficiency of Mo and W, and the flue gas recovery process was no longer required, which is beneficial to industrial application.

Development of a recovery process of thorium and possible separation of rare earths from Korean monazite

ABSTRACT Systematic studies were carried out to leach out rare earths and recover thorium from Korean monazite. Monazite was processed with acid baking process (sulfation) where rare earth elements (REEs) and thorium phosphates were transformed to water-soluble sulfates. Various experimental factors such as temperature, H2SO4/monazite concentrate ratio and time were studied to get optimized sulfation system. Near to 88% of leaching of REEs and Th was performed after sulfation followed by water leaching. Moreover, by using 0.1 mol/L of primary amine Primene JM-T (tri-alkyl-methylamine), thorium was separated (more than 95%) from the light rare earth elements present in the leach liquor. Subsequently, rare earth elements were separated by solvent extraction technique using Cyanex 572 as an extractant at different pH conditions. High separation coefficients for different rare earths were obtained with Cyanex 572, while Primene JM-T resulted in the complete separation of the thorium from the leach liquor.

Hydrometallurgical recovery of manganese and nickel and isolation of tantalum from obsolete tantalum capacitor

Tantalum capacitor demand is rapidly growing, primarily from the electronic and superalloy industries. Indeed, the global tantalum market is anticipated to boost at a compound annual growth rate of around 6% over the next decade. With increasing technological advancements, electronics' obsolescence rate has also increased. The obsolete capacitors from these electronics are a rich secondary resource for recycling strategically and economically significant metals. In this article, we have developed an environment-friendly hydrometallurgical route for recovery of manganese and nickel from the tantalum capacitors. Firstly, silica-free tantalum capacitor procured after pre-processing was leached using hydrochloric acid (1–3 M) for preferred dissolution of manganese and nickel, to facilitate a tantalum-rich residue. Manganese was then selectively separated from leach liquor using solvent extraction with D2EHPA and CYANEX272, with the extraction efficiency of each reagent compared. Quantitative dissolution of both manganese (99.9%) and nickel (98.9%), with no tantalum dissolution, was witnessed under the optimized leaching condition of 3 M HCl, 50 g/l pulp density, 60 °C, and 120 min. Kinetic data for manganese and nickel in the temperature range of 30–60 °C demonstrated the leaching reaction at the surface to be the rate controlling step. D2EHPA and CYANEX272 each showed excellent selectivity for manganese under the optimized conditions. However, CYANEX272 proved to be a better extractant in light of higher extraction efficiency in single-stage extraction (∼75%), than D2EHPA (∼40%), with less organic consumption. Above 99% manganese was selectively extracted with predicted 2-stages extraction by McCabe-Thiele plot using CYANEX272 under the optimized condition.

Lithium-Ion Battery Recycling: Metal Recovery from Electrolyte and Cathode Materials by Electrodialysis

The potential of electrodialysis to recycle spent lithium-ion batteries was assessed by investigating the recovery of lithium(I) from a synthetic solution representative of the aqueous effluent generated by shredding spent lithium-ion batteries underwater. Likewise, electrodialysis was tested for the selective recovery of lithium(I) towards cobalt(II), nickel(II) and manganese(II) from a synthetic solution representative of the leaching liquor of cathode materials. NMR spectroscopy showed that the implementation of electrodialysis to extract lithium from the aqueous effluent produced during battery shredding underwater should take into account the presence of HF generated by PF6− hydrolysis. In particular, it seems relevant to perform shredding under calcium chloride solution in order to precipitate fluoride and reduce HF generation. This work also showed that electrodialysis is an interesting technology for selectively recovering lithium from the leach solution of spent cathode materials, providing that divalent cations were previously removed to avoid metal precipitation inside the electrodialysis membranes. After removing cobalt(II) and nickel(II) at pH 2.8 and manganese(II) partially at pH 5.5 by using the ion exchange resin Dowex M4195, it is possible to extract and selectively concentrate lithium by electrodialysis without coextracting manganese(II) by using a lithium-selective membrane (faradic efficiency of 57.6%, permselectivity for lithium towards manganese of 6.9). Finally, a hybrid flowsheet implementing mineral processing and hydrometallurgy, including electrodialysis, ion exchange and crystallization stages, was proposed based on these results to reduce effluent generation and produce metal salts from spent lithium-ion battery.

Recovery of Pd(II) by solvent extraction with a dithiophenol-based extractant from the undiluted leachate of spent automotive catalysts followed by water scrubbing and thiourea stripping

Extractants with high recognition ability for specific platinum-group metals are essential for the selective and effective recovery of these valuable metals from spent materials. We previously developed extractants that could separate Pd(II) from the leachate of spent automotive catalysts; however, some challenges remained. In this study, a dithiophenol-based extractant bearing three sulfur atoms was developed to effectively and rapidly recover Pd(II) from the undiluted leachate of spent automotive catalysts. The Pd(II) extraction ability (E%) of this extractant was evaluated via liquid–liquid extraction experiments using a Pd(II) single-metal solution with different shaking times and HCl concentrations, Job plot analysis, and extraction behavior studies of Pd(II) in a simulated solution. Effective Pd(II) extraction from the undiluted leach liquor was achieved by adjusting the extractant concentration. After extraction, the metal-loaded organic phase was scrubbed with water to remove the Fe(III) co-extracted from the liquor. The Pd(II) ions were then stripped from the scrubbed organic phase using 0.1 M thiourea. The stripping produced the Pd(II) salt [Pd(thiourea)4]2+∙2Cl− with a stripping efficiency of ca. 100%. The Pd(II) extraction mechanism was estimated using single-crystal XRD and 1H NMR spectroscopy. The DFT calculations indicated that at least two sulfur atoms of the synthesized extractant are involved in the extraction of one Pd(II) atom.

Lithium extraction from β-spodumene: A comparison of keatite and analcime processes

The conventional processing of β-spodumene involves decrepitation at about 1100 °C, digestion with concentrated sulfuric acid at 250 °C, and several purification stages that identify the process with high energy, feedstock, and by-product intensity. In addition to the low-value by-product of sodium sulfate (Na2SO4), the disposal cost of another by-product, hydrogen aluminosilicate (HAlSi2O6, aka keatite-HAlSi2O6), drives the research to avoid its formation in lithium refineries or converting this material into marketable products such as zeolites. Two processes are developed to leach lithium from β-spodumene in a single digestion step using solutions of NaCl, with and without the addition of NaOH, operating at up to 200 °C. The optimised processes extract at least 92.9% of Li by varying the leaching time, temperature, liquid to solid mass ratio, NaCl/β-spodumene mass ratio, solution pH and agitation. The two processes are simple, prevent using concentrated sulfuric acid and preclude forming HAlSi2O6 and Na2SO4 by-products, resulting in significantly lower amounts of impurities in the leach liquor, and high selectivity for lithium extraction. The keatite process functions at circumneutral pH, high NaCl/β-spodumene and L/S ratios and generates sodium aluminosilicate (keatite-NaAlSi2O6) as a by-product. The analcime process requires alkaline pH to produce analcime (NaAlSi2O6·H2O) as a by-product. The study demonstrates a shift in the mechanism between circumneutral and alkaline conditions from ion exchange to dissolution-precipitation (i.e., recrystallisation). In an analogy to keatite and analcime processes for NaCl, we also investigate the extraction of lithium from β-spodumene with KCl with and without KOH but find both reactions to be ineffective in recovering Li. The analcime process offers a cleaner and less hazardous alternative to the conventional sulfuric acid process while maintaining a high lithium extraction effectiveness, rapid reaction rates and high concentration of Li in the leach.

Solvent Extraction Studies of Copper from a Heap Leach Liquor Using Mextral 5640H

In this study the extractive capability of Mextral 5640H was investigated for extraction of copper from a heap leach liquor. In this regard, the influence of parameters such as pH (0.2–2.8), extractant concentration in kerosene diluent (2.5%–10% v/v), temperature (25–70 °C), contact time (0–300 s), stirring speed (100–1200 rpm), phase ratio (O/A) (0.6–1.8) and Cu initial concentration (0.5–2 g/L) in the leach liquor were examined and optimized. The findings demonstrated that the Mextral 5640H extractant had a very high efficiency and selectivity in copper extraction from the leachate. 98.17% Cu, with less than 0.5% of Fe and Mn, were extracted at pH 1.6, 10% (v/v) Mextral 5640H concentration, ambient temperature (25 °C), 400 rpm stirring speed, 2 min contact time and an O/A phase ratio of 1:1. Under equilibrium conditions it was found that one mol of Cu is extracted by 7 mol of Mextral 5640H. Additionally, analysis using a McCabe–Thiele diagram suggests a two-stage extraction to reach the maximum extraction of copper (99.5%) from the leachate at operational condition using industrial mixer-settlers. Furthermore, a thermodynamic study was conducted, and the measured values of ΔH = 15.13 kJ/mol, ΔG = −6.95 kJ/mol and ΔS = 74.10 J/mol/K indicate an endothermic, spontaneous nature and high affinity of copper extraction.