Pregnant Leach Solution Research Articles

Diffusion dialysis and extraction integrated system for recovery of cobalt(II) from industrial effluent

This paper presents multistage hydrometallurgical separation of Co(II) from wastewater, achieved in an integrated system containing diffusion dialysis (DD) to decrease the acidity of the industrial effluent – pregnant leach solution (PLS), followed by precipitation of Al(III), Fe(III) and Cr(III) hydroxides, selective extraction of Co(II) with bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), stripping of Co(II) from the loaded organic phase to form an electrolyte. DD results indicate that minimum metal ion content in the dialysate and high concentration of H+ (1.5−3 M) can be achieved by conducting the process at a low flow rate, but for a longer time. The feed after DD was effectively purified by precipitation of Cr(III), Al(III) hydroxides, and some admixtures of Cu(II) and Fe(III) to ensure that those metals will not disturb the liquid-liquid extraction of Co(II) at pH 5.2. High distribution ratio values for Co(II) extraction mean that ions of this metal can be selectively separated from the remaining ions present in the feed, especially Ni(II), and transported to the organic phase. The application of H2SO4 solution and the dialysate as stripping phases indicates that the dialysate more efficiently stripped most of the metal ions from the extract, thus forming Co(II) rich electrolyte for further electrodeposition of the metal. Finally, Co(II) electrowinning from a model stripping solution was investigated and the preliminary results showed that good quality metallic cobalt can be deposited.

Isolation of Zinc, Copper, and Nickel from Glutamate Media by Solvent Extraction

Solvent extraction scheme to isolate Zn, Cu, and Ni from glutamate media as hypothetical product of electric arc furnace dust alkaline leaching was developed, with concentrations being 17.6, 0.35, and 0.14 g/L, respectively. Three extractants were investigated: Cyanex 272, DEHPA, and Acorga M5640 selectively separated Zn, Ni, and Cu from each other. Aside from pH, parameters investigated included O/A ratio, extractant concentration in kerosene as diluent, and sulfuric acid concentration as stripping agent. pH was the most critical factor in determining the separation factor among three metals since pH controlled metal speciation in pregnant leach solution and regulated the interaction between metal ions and extractant. Based on previous studies, a flowsheet for Zn, Cu, and Ni isolation is proposed, which obeys the following sequence: Zn separated from Cu and Ni by Cyanex 272 (in pregnant leach solution at pH 8, log separation factor Zn–Cu 4.78, Zn–Ni 2.51), followed by Ni separation from Cu by DEHPA (in raffinate at pH 7, log separation factor Ni–Cu 3.92), and finally Cu extraction (in raffinate at pH 4, log distribution coefficient 3.19). Sulfuric acid was proved to be a suitable stripping agent with optimum concentrations of Zn, Ni, and Cu being 0.5, 0.25, and 2 M, respectively.

Selective leaching of a mixed nickel-cobalt hydroxide precipitate in sulphuric acid solution with potassium permanganate as oxidant

ABSTRACT Selective leaching of a mixed nickel-cobalt hydroxide precipitate was investigated using potassium permanganate as oxidant in sulfuric acid solution. 94.9% Ni, 50% Co and 0.6% Mn were dissolved under the following conditions: sulfuric acid concentration of 0.75 M, potassium permanganate of 5 g/L, temperature of 30°C, leaching duration of 60 min, solid-to-liquid ratio of 1/10, and stirring speed of 400rpm. The pregnant leach solution was subjected to a solvent extraction process. 98% Co and 99% Mn were extracted at pH 4.84 with 30% (v/v) Cyanex 272, leaving essentially all nickel in the raffinate. Based on the experimental results, a flowsheet is proposed.

Ammoniacal Solvoleaching of Copper from High-Grade Chrysocolla

The copper silicate ore chrysocolla forms a large potential copper resource, which has not yet been fully exploited, due to difficulties associated with its beneficiation by flotation and metallurgical processing. Direct acid leaching of chrysocolla causes silica gel formation. Therefore, in this work, the feasibility of solvometallurgical methods to leach copper from high-grade chrysocolla while avoiding issues with silica gel formation was assessed. Ammoniacal solvoleaching was performed with a solvent comprising the chelating extractant LIX 984 N or the acidic extractant Versatic acid 10 in an aliphatic diluent (ShellSol D70 or GTL Fluid G70), combined with a small volume of aqueous ammonia. In the three-phase system, aqueous ammonia dissolves copper from milled and sieved chrysocolla, while copper is simultaneously extracted to the organic phase, releasing ammonia that can be reused for further extraction. The best results were obtained with LIX 984 N as extractant: using a 50 vol% LIX 984 N solution, about 75% of copper could be extracted after 60 min of leaching at 25 °C. The stripping of copper from the pregnant leach solution was optimized. Quantitative stripping of copper was achieved with 1.89 M sulfuric acid and the final aqueous solution of copper sulfate had a concentration of 33 g L−1. Experiments in a leaching reactor (1 L) and small battery of mixer-settlers (3 stages, 35 and 143 mL effective volume in the mixer and the settler, respectively, per stage) were successfully conducted and allowed to recover copper with a purity of 99.9%. A conceptual flow sheet has been developed.Graphical

Process design for the Ivana uranium-vanadium mill

ABSTRACT Blue Sky Uranium Corporation’s Amarillo Grande Project in Rio Negro Province, Argentina, features the Ivana near-surface uranium deposit, which has significant vanadium credits. This article begins by reviewing the project location and the specific qualities of the Ivana deposit that led to decisions on the Ivana mining and mineral processing methods. The bulk of the article describes the thought process that resulted in the innovative and unique conceptual milling process for uranium and vanadium recovery. The deposit mineralogy is described in detail. The milling process begins with attrition scrubbing of the mined material to reject coarser barren material and increase mill feed grade by four times. Alkaline carbonate leaching is followed by pressure filtration. The pregnant leach solution is concentrated with concomitant reagent and water recovery using membrane filtration. Activated carbon columns remove the organic impurities from the concentrated leach solution, which then feeds the unique solvent extraction circuit. The solvent extraction process separates uranium and vanadium. Uranium is precipitated as uranium peroxide, which is calcined to U3O8. Vanadium is precipitated as ammonium vanadate, which is calcined to V2O5. The process releases no liquid effluents to the environment.

Nitrophosphate Solution Purification by Calcium Precipitation as Gypsum

Phosphate ores are one of the most important secondary sources of rare earth elements (REEs). The Esfordi phosphate concentrate (Yazd Province, Iran) contains 13.1% phosphate, 34.6% calcium, and 1.09% REEs. After selective leaching of the concentrate with 35% nitric acid at 60°C for 70 min, a pregnant leach (nitrophosphate) solution containing 143.6 g/L calcium, 53.1 g/L phosphorus, and other impurities was obtained. Sulfuric acid was used to remove calcium from the pregnant leach solution in the form of gypsum, and the effect of the stoichiometric ratio of sulfate to calcium was investigated. The results showed that at a sulfate-to-calcium molar ratio of 1, 99.5% of calcium, 95.2% of cerium, 92.8% of La, and 96.5% of Nd were precipitated from the solution. Phosphate co-precipitation with gypsum was < 10%. As the stoichiometric ratio of sulfate to calcium increased, the co-precipitation rate of phosphate decreased. The results of the present study showed that in the two-stage leaching method of REE production from phosphate ores, calcium precipitation in the form of gypsum is an effective method for purifying the solution from calcium.

Effect of multistage solution–mineral contact in in-situ recovery for low-grade natural copper samples: Extraction, acid consumption, gangue-mineral changes and precipitation

Recent decreases in the grades of copper reserves have stimulated interest in alternative mining technologies, such as in-situ recovery (ISR), which may be an attractive mining approach for low-grade ores. In ISR operations, lixiviant contacts subsurface ore when it is pumped through the deposit. Continuous flow of lixiviant with suitable properties (such as pH and solution potential, Eh) is required from the wellfield injection point through the ore to the recovery point. Leach solution pH and Eh adjustment is not possible between boreholes and therefore, undesired precipitate formation may result, which could produce blockages and restrict solution flow. Our experiments aimed to simulate the chemical processes that may occur when leach solution travels through an ore deposit from the injection to the recovery well by contacting a pregnant leach solution with fresh ore over multiple stages. Low-grade natural ore that contained refractory copper sulfides mixed with gangue minerals was leached with iron (III) as an oxidant in sulfuric, hydrochloric or methanesulfonic acid at 90 °C. The leach solution was contacted for 72 h with fresh ore in five successive stages, without acid or oxidant replenishment. Although copper extraction continued for the duration of the five stages, the copper extraction dropped off after two contact stages. Precipitates formed in all solutions after three contact stages; akaganeite precipitated in the chloride systems and jarosite and gypsum formed in the sulfate systems after the second contact stage. The extent of precipitation is predicted to increase with an increase in temperature and pH. These findings provide insights into the behaviour that could be expected in ISR operations and factors that influence borehole spacing and ensure continuous lixiviant–ore contact subsurface.

Leaching and recovery of gold from ore in cyanide-free glycine media

Glycine has recently gained plenty of attention in gold processing as an alternative lixiviant to cyanide due to its non-toxicity, efficiency in metal dissolution as well as selectivity for valuable metals. This paper presents an investigation on the combination of agitated reactor leaching and recovery of gold from mildly refractory ore in cyanide-free alkaline glycine media. Optimal leaching parameters for gold extraction were evaluated using response surface methodology. The investigated parameter range was 0.5–2 M for glycine concentration, pH of 10–12 and temperatures of 23–60 °C, with constant leaching time (24 h) and solid/liquid ratio (100 g/L). Based on the experimental series, a mathematical tool was built to predict gold extraction. It was found that, in the investigated parameter range, glycine concentration did not have a statistically significant effect on gold dissolution. Conversely, both temperature and pH had a substantial role in leaching kinetics. The statistical model suggested that the optimal conditions for gold dissolution were 1.25 M of glycine, pH = 12, and T = 60 °C, corresponding to a predicted 87% gold extraction. The experimental verification showed good reliability of the model with 90% extraction of gold achieved under the predicted optimum conditions. The addition of 15 g/L of activated carbon to the pregnant leach solution (PLS) could provide 100% recovery of gold from solution onto activated carbon, i.e. holistic recovery of 90%. Presence of carbon in leach (CIL) resulted in slightly lower (95%) gold uptake from solution and significantly decreased the holistic gold recovery down to 77%. Additionally, the applicability of direct electrochemical carbon-free recovery method, namely electrodeposition–redox replacement (EDRR), was investigated. In the synthetic solution, a gold recovery as high as 88% was achieved (1247 cycles). However, in the real PLS, only 35% of gold was recovered, which is attributed to different speciation of metals and presence of the other dissolved elements.

Effect of the chloride content of seawater on the copper solvent extraction using Acorga M5774 and LIX 984N extractants

In recent years, the application of non-conventional water sources, such as seawater in metal extraction industries located in arid and semi-arid areas have been increased. In this study, the integration of seawater in the solvent extraction of copper hydrometallurgical operation was investigated. Accordingly, two commercial copper extractants, Acorga M5774 and LIX 984N were used in extraction of copper from a sulfate–chloride solution containing seawater. The results showed a higher concentration of copper in the pregnant leach solution (PLS) as a result of using seawater; however, the concentration of Fe and the impurities that are associated with seawater, i.e., Cl, Na, Mg, Ca, K were also increased. The presence of the chloride ion resulted in a higher copper extraction at pH values below 1.5. Synergistic system of LIX 984 N and Acorga M5774 (1:1 vol mixture 15% v/v) was found more efficient in extraction of copper at pH values below 1.5 in comparison to sole LIX 984 N and Acorga M5774. Similarly, the extraction of impurities (Na, Mg, K, and Cl) were observed less when a mixture of extractants were used. The results showed that increasing the chloride concentration had a negative effect on copper extraction as the organic to aqueous ratio was decreased. The copper extraction mechanism was also studied using single LIX 984N, Acorga M5774, and a 1:1 vol mixture of these two extractants at chloride concentrations of 0 and 40 g/L. Increasing the chloride concentration resulted in the involvement of more organic molecules.

Environmental Aspects of Cu Recovery from Evaporative Solids on the Surface of Old Weathered Tailings: Sarcheshmeh Mine, SE Iran

The enormous amount of water-soluble evaporative solids (about 150 t/ha) that has formed on the old weathered tailings in the semi-arid climate of the Sarcheshmeh area, in SE Iran, stores acidity and potentially toxic elements, such as Cd (8.8 ± 3.7 mg/kg), Co (242 ± 43 mg/kg), Cu (11,220 ± 3500 mg/kg), Mn (8400 ± 3400 mg/kg), Ni (176 ± 38 mg/kg), S (12.82 ± 1.01%), and Zn (2670 ± 880 mg/kg). We assessed the potential of recovering Cu from these evaporative solids and the likely environmental aspects of doing so. The total Cu concentrations ranged from 7380 to 17,850 mg/kg. The mean Cu concentration in the produced pregnant leach solution (PLS) was 13,210 mg/L, which after cementation reached 94.40 mg/L, corresponding to a Cu recovery efficiency of 99.2%. During the cementation process, the Fe concentration increased in the final barren solution (FBS). In addition to the positive environmental role of Fe in the co-precipitation of potentially hazardous trace elements, the pH range of FBSs was 4.02–4.17, which was higher than the pH range of the initial PLSs (pH 3.25–3.40). Thus, collecting evaporative solids from the surface of old-weathered tailings can provide valuable Cu and improve the quality of the tailings pond recycling water by reducing the risk of diminishing of water quality, especially during heavy rainfall events.

Design of an advanced hydrometallurgy process for the intensified and optimized industrial recovery of scandium from bauxite residue

This study aims to the industrial scale development of Bauxite Residue leaching for Scandium recovery, by optimizing a hydrometallurgy method and taking account appropriate design concepts for process intensification. Approaching the design issue either by adapting arithmetic methods, or using related software, showed inconsistent convergence, which is caused by the process particularities and non-conventional characteristics (i.e., feed flow-rates dependent on reflux ratio, hybrid of continuous and intermittent processes, etc.). Seeking also for process economic viability, typical cost-based objective functions showed to deviate from optima with a real economic sense. To deal with both challenges, necessary modeling simplification for advanced Leaching with Mineral Acids (LMA) was made, coupled with commercial economics and profit-based objective functions. Under the design aspect, additional constraints were introduced for the Pregnant Leach Solution (PLS) that were arisen from the subsequent Resin ion eXchange (RX) and the avoiding of colloidal silica gel formation. The optimized leaching resulted to the highest possible: solids-to-liquid ratio; molarity for RX-complying PLS; and temperature for acceptable [Si] (e.g., SL = 33.3 %, CFA = 0.31 M, TL = 32 °C, PL = 1 atm, N = 1.01, τL≥1 h). Also, the developed simulation model can have expanded application for different LMA cases, and the introduced economic evaluation method is suitable for the production of various internationally traded commodities.

Leaching of Rare Earth Elements from Central Appalachian Coal Seam Underclays

Rare earth elements (REE) are necessary for advanced technological and energy applications. To support the emerging need, it is necessary to identify new domestic sources of REE and technologies to separate and recover saleable REE product in a safe and economical manner. Underclay rock associated with Central Appalachian coal seams and prevalent in coal utilization waste products is an alternative source of REE to hard rock ores that are mainly composed of highly refractory REE-bearing minerals. This study utilizes a suite of analytical techniques and benchtop leaching tests to characterize the properties and leachability of the coal seam underclays sampled. Laboratory bench-top and flow-through reactor leaching experiments were conducted on underclay rock powders to produce a pregnant leach solution (PLS) that has relatively low concentrations of gangue elements Al, Si, Fe, and Th and is amenable to further processing steps to recover and produce purified REE product. The leaching method described here uses a chelating agent, the citrate anion, to solubilize elements that are adsorbed, or weakly bonded to the surface of clay minerals or other mineral solid phases in the rock. The citrate PLS produced from leaching specific underclay powders contains relatively higher concentrations of REE and lower concentrations of gangue elements compared to PLS produced from sequential digestion using ammonium sulfate and mineral acids. Citrate solution leaching of underclay produces a PLS with lower concentrations of gangue elements and higher concentrations of REE than achieved with hydrochloric acid or sulfuric acid. The results provide a preliminary assessment of the types of REE-bearing minerals and potential leachability of coal seam underclays from the Central Appalachian basin.

Monosodium Glutamate as Selective Lixiviant for Alkaline Leaching of Zinc and Copper from Electric Arc Furnace Dust

The efficacy of monosodium glutamate (MSG) as a lixiviant for the selective and sustainable leaching of zinc and copper from electric arc furnace dust was tested. Batch leaching studies and XRD, XRF and SEM-EDS characterization confirmed the high leaching efficiency of zinc (reaching 99%) and copper (reaching 86%) leaving behind Fe, Al, Ca and Mg in the leaching residue. The separation factor (concentration ratio in pregnant leach solution) between zinc vs. other elements, and copper vs. other elements in the optimum condition could reach 11,700 and 250 times, respectively. The optimum conditions for the leaching scheme were pH 9, MSG concentration 1 M and pulp density 50 g/L. Kinetic studies (leaching time and temperature) revealed that the saturation value of leaching efficiency was attained within 2 h for zinc and 4 h for copper. Modeling of the kinetic experimental data indicated that the role of temperature on the leaching process was minor. The study also demonstrated the possibility of MSG recycling from pregnant leach solutions by precipitation as glutamic acid (&gt;90% recovery).

Cobalt–Nickel Pertraction Refinery to Process Pregnant Leach Solution from Recycled Spent Catalysts Part 1: Cobalt Extraction from a Binary System

ABSTRACT Owing to the recent increase in the global demand for Co, new cobalt–nickel refinery capacity is required. While solvent extraction is one of the most important separation and purification techniques in hydrometallurgy, pertraction, also called membrane-based solvent extraction, offers various advantages over conventional solvent extraction. In this study, pertraction was used to purify a pregnant leach solution obtained from spent hydrotreatment catalysts that had been produced by Minemet. A block flow diagram and mass balance for the cobalt–nickel refinery were developed and used in the experimental design. Extraction isotherms were determined as well as mass transfers optimised using a circulating batch pertraction setup for both synthetic and industrial cobalt–nickel mixed metal solutions. A comprehensive set of models was applied to translate the experimental data into a conceptual design of the industrial cobalt–nickel pertraction refinery to process pregnant leach solution from the Minemet plant.

Effect of Holed Ferrum electrodes (HFE) on the efficiency of the electrocoagulation process for copper recovery and optimization of parameters, using RSM

The present study investigated the electrocoagulation (EC) process using holed Ferrum electrodes (HFE) in the mineral industries for copper recovery from the pregnant leach solution (PLS). To this end, the response surface methodology was used to optimize factors affecting copper recovery in the EC process. The Box-Behnken design was employed to optimize experiments and effects of four independent variables - including initial pH (X1), current density (X2), electrode distance (X3), and electrolysis time (X4) - were studied to investigate copper recovery. Moreover, a linear model was used to calculate the copper recovery rate. The most important independent variables and their interaction were evaluated using ANOVA. Optimal operating conditions with copper recovery were obtained at the initial pH of 5.2, current density of 438.2 mA/cm2, electrode distance of 2.10 cm, and electrolysis time of 68.05 min. The copper grade yield was above 90% that was shown by XRD and SEM-EDAX analyses. The results of the SEM-EDAX analysis indicated that the main elements contained in particles included copper (82.5%–90.4%), Fe (6.2%–8.6%), and O2 (3.4%–8.9%), respectively. Moreover, the results of XRD studies confirmed that the minerals formed in the studied samples were mostly classified into two main phases of copper and cuprite, and that the rare phase included quartz minerals. It is concluded that the EC process as a reliable method has highly desirable capability in the recovery of soluble copper and recycling of water from mineral industries, especially in mineral processing plants.

Improvement effect of organic ligands on chalcopyrite leaching in the aqueous medium of sulfuric acid‑hydrogen peroxide-ethylene glycol

The addition of ethylenediaminetetraacetic acid (EDTA) to a 1 M H2O2 leaching solution with low concentrations of sulfuric acid (0.007 M) and ethylene glycol (EG) (0.1 M) promotes significant increases of copper and iron leached from chalcopyrite. However, copper purification by solvent extraction is not possible due to the elevated stability of copper-EDTA and iron-EDTA complexes in the resulting leach liquor. Therefore, a two-stage process is presented that enables copper and iron dissolution at ambient temperature and pressure (26 °C and 101.325 kPa, respectively), without the necessity of solvent extraction. The proposed process uses the H2SO4-H2O2-ethylene glycol leaching solution in combination with organic ligands (oxalic acid (OxA) or EDTA). The first stage, using the leaching solution with oxalic acid, dissolved 29.5% of iron and transformed 49% of the copper to an oxalate salt; while in the second stage, the H2SO4-H2O2-ethylene glycol-EDTA leaching solution favored both the rapid dissolution of the copper oxalate salt and the chalcopyrite that did not react in the first stage. In this manner, the pregnant leach solution (PLS) from the second stage contained 90% and 35% of the total copper and iron, respectively, which may be electrowon directly. These results showed that the use of organic ligands promotes the formation of copper and iron complexes which help to delay, but not to avoid the decomposition of hydrogen peroxide due to a Fenton reaction and therefore, this results in an increase of the percentages of copper and iron leached, which permits processing at higher pulp density (50 g/L).

Nickel Metal Hydride Battery Waste: Mechano-hydrometallurgical Experimental Study on Recycling Aspects

In this research, the recycling of industrially collected and crushed nickel metal hydride battery waste, rich in valuable metals such as Ni and rare earth elements (REE), was investigated. The crushed waste was characterized based on elemental distribution per particle size class and density. Although issues with sieving, such as agglomeration of shredded separator fibers, were observed, a good separation of Fe and plastics could be achieved by using a 1-mm sieve size. It was observed that, as the waste battery particles were washed with water, some organic compounds were dissolved. Acid consumption of 14 mol H+ ions per 1 kg of battery sample (sieve fraction—1 mm) was determined to be sufficient to achieve the desired final pH of < 1. Selectivity of the leaching at higher equilibrium pH was also investigated by using dilute H2SO4. Pregnant leach solution rich in Ni (46 g/L) and REEs (La: 9 g/L, Ce: 7.5 g/L, Pr: 1.4 g/L, Sm: 0.29 g/L, Y: 0.17 g/L) was obtained and REE precipitation was investigated as a function of dilute Na2SO4 solution concentration (0.01–0.5 M) at a temperature of 50 °C. The best precipitation efficiency was achieved with a Na:REE ratio of 9.1, which resulted in a > 99% precipitation efficiency for the REEs.

Recovery of valuable metals from mining and mineral processing waste

Ammonia-thiosulfate-copper leaching, aided by a direct current electrochemical impact, is proposed to extract gold (Au), silver (Ag) and copper (Cu) from old flotation tailings mixed with waste rock. Over 80 % of Au available in the waste material and over 75 % of Cu and Ag were extracted into the pregnant leach solution (PLS) at room temperature. Electrowinning from that PLS recovered around 92 % of Au and Cu, and about 87 % of Ag in the cathode deposit that is suitable for further metallurgical refining. The results are better, compared to leaching in the same system but without electrochemical impact and at air addition. The proposed direct current aided method is promising and more environmentally friendly compared to cyanide and even to sodium thiosulfate leaching.

Recovery of yttrium and europium from spent fluorescent lamps using pure levulinic acid and the deep eutectic solvent levulinic acid-choline chloride.

A solvometallurgical approach for the recovery of rare-earth elements from lamp phosphor waste was developed. The solubility of individual phosphors in different deep-eutectic solvents (DESs) was measured. The DES levulinic acid–choline chloride (xChCl = 0.33) showed high solubility of the YOX phosphor (Y2O3:Eu3+) and low solubility of the HALO phosphor (Sr,Ca)10(PO4)(Cl,F)2:Sb3+,Mn2+, which does not contain any rare-earth element. This DES was selected for further investigation. When the DES was compared to pure levulinic acid, very similar leaching behaviour was observed, showing that the proton activity is more important than the chloride as a metal ligand. The leaching of YOX and HALO using levulinic acid–choline chloride (xChCl = 0.33) or pure levulinic acid was optimised in terms of water content, temperature and leaching time. The optimised parameters were validated in a synthetic mixture of phosphors and in real lamp phosphor waste. The co-dissolution of HALO is higher in the real waste than in the synthetic mixture. The real waste was also leached with an aqueous solution of hydrochloric acid, which was non-selective against dissolution of YOX, and with the functionalised ionic liquid betainium bis(trifluoromethylsulfonyl)imide. The ionic liquid gave a similar selectivity as levulinic acid, but is much more expensive. The recovery of the metals from the pregnant leach solution was tested via precipitation with oxalic acid and solvent extraction. Oxalic acid precipitation was not suitable for the DES system. The metals could be extracted via solvent extraction with the acidic extractant bis(2-ethylhexyl)phosphoric acid (D2EHPA) and stripped by an aqueous hydrochloric acid solution. Pure levulinic acid was found to be more suitable than the corresponding ChCl-based DES for the selective recovery of YOX.

Enrichment and extraction of lanthanum from Belitung silica sand using sulfuric acid heap leaching, precipitation and complexation with phytic acid

In this study, enrichment and extraction of lanthanum from Belitung silica sand was carried out using heap leaching, precipitation and complexation methods. Complexation with phytic acid with impurities metal ions on pregnant leach solution (PLS) from silica sand at room temperature was also investigated. This method is cheap, practical, no destruction needed, and the preparation is simple and easy. The precipitation method using sodium sulfate was carried out to separate the metals and impurities present in the solution. The heap leaching of the metals was performed by varying the parameters such as acid concentration (0.001–3 M) and volume of sulfuric acid solution (50–250 mL). Concentration of lanthanide and composition of metal ions of samples were determined using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The optimum concentration and volume of H2SO4 as a leaching agent was 3 M and 250 mL, respectively, with the result of the lanthanum salt as high as 1.637 ppm. The hexaphosphate groups of phytic acid as active sites is favorable selective to bind with Al3+ metal ions, thus it is expected to have high effectiveness for lanthanum enrichment. From the ICP-OES results in the complexation using phytic acid, lanthanum was obtained of 0.709 ppm (11.29%) with its purity of ∼67%. These results suggested that lanthanum can be extracted from Belitung silica sand using the acid leaching, precipitation and complexation methods.