Mixed solvent systems for the extraction and stripping of iron(III) from concentrated acid chloride solutions

The extraction of concentrated iron(III) from acid chloride solutions has been investigated with methyl isobutyl ketone (MIBK), tri-n-butyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA), and their mixtures in various proportions, at different acid concentrations. On comparing the extraction of iron(III) with mixed and individual extractant, it was found that both D2EHPA-MIBK and D2EHPA-TBP mixtures exhibit synergism, the latter having better extraction ability. The synergistic coefficients, at different initial acid concentrations for each mixed extractant system, were evaluated and compared. An increase in the concentration of MIBK and TBP in the mixed organic resulted in higher synergistic coefficient. The stripping of iron(III) from loaded D2EHPA was found to increase with the strip feed acid concentration, while from loaded organic mixtures, it initially increased and then decreased. Stripping of iron(III) from D2EHPA-MIBK loaded solvent is better then D2EHPA-TBP. The extracted iron species formed and the stripping reactions have been proposed. Ultraviolet visible spectra of the stripped organic phase support the result and the proposed mechanisms.     

The extraction of iron(III) from aqueous sulphate solutions by primene sulphate

A study of the extraction of iron(III) from aqueous sulphate media by the primary amine Primene 81R at 50°C has been made. The compound extracted from the organic phase with Primene 81R sulphate in kerosene has been isolated and recrystallized from a methanol-acetone mixture and has been shown to have the stoichiometric formula 3(RNH₃)₂SO₄·(Fe(OH)SO₄)₂ represents the alkyl groups associated with the amine. It has been shown that the extraction of iron(III) occurs by an adduct formation reaction between primary amine sulphate molecules and the species IFe(OH)SO₄I₂ from the aqueous phase. On the basis of the experimental data and spectral studies a dimeric structure is suggested for the extracted complex.     

The extraction of iron(III) from aqueous acid solutions by di(2-ethylhexyl)phosphoric acid

The extraction of iron(III) from aqueous solutions containing sulphuric, hydrochloric and nitric acids by di(2-ethylhexyl)phosphoric acid (DEHPA) in kerosene has been investigated under different conditions. As a result, it is found that although extraction is dominated by an ion-exchange reaction, the rate of iron(III) extraction from sulphuric acid solutions to reach equilibrium is relatively slow in comparison with that from hydrochloric or nitric acid solutions. In the extraction from aqueous solutions containing hydrochloric or nitric acid, however, the DEHPA combines with iron(III) according to the solvating reaction at higher aqueous acidity. From studies on the rate of the extraction from sulphuric acid solutions, examined under non-equilibrium, it is confirmed that dependencies of extraction rate on hydrogen ion and DEHPA concentrations are in the first and inverse first orders, respectively. The hydrolyzed species is considered to interpret the extraction mechanism in this system.     

The extraction of Fe(III) from ammonium chloride solutions with capric acid

Extraction equilibria in the FeCl₃NH₄Clcapric acidCCl₄ system were investigated. Using slope analysis the results were interpreted in terms of the formation of the binuclear species [Fe(OH)R₂]₂ and [Fe(OH)₂R·HR]₂ in the organic phase. From calculations of the complex formation function and the experimental data it was shown that the effect of Fe(III) hydrolysis in the aqueous phase on metal extraction may be neglected.     

The solvent extraction of lead from chloride solutions using di(2-ethylhexyl)phosphoric acid

Lead has been extracted from chloride solutions into kerosene containing excess di(2-ethylhexyl)phosphoric acid, using various concentrations of metal and extractant. Extraction proceeded readily, but the results indicated that 1.6 hydrogen ions were exchanged per atom of lead extracted, rather than 2.0 as would be expected for a divalent metal ion. Extraction was unaffected by metal concentration over the range studied (0.1–1.0 g l^?1), and the results were highly consistent. The unique log D vs. pH relation allowed simple collection of data for contact stage evaluation by rearrangement of the familiar solvent extraction equations and use of empirically derived constants. An S-shaped extraction isotherm resulted, which limits the ease with which aqueous lead concentrations may be reduced by extraction with di(2-ethylhexyl)phosphoric acid.     

As,Sb, and Fe removal from industrial copper electrolyte by solvent displacement crystallisation technique

The presence of impurities in the copper electrolyte increases the energy consumption of an electrorefining process and contaminates the deposited copper on cathode. The concentration of impurities increases over time making it necessary to remove them from the solution. This research introduces a fast, effective, and simple method to refine the industrial electrolyte from arsenic, iron and antimony by solvent displacement crystallisation technique. In this method, when alcohol is added to the electrolyte, the impurities precipitate from the solution as amorphous arsenato antimonite phase. Results show that Fe, Sb, and As are removed from the copper electrolyte by 75.2, 96.9 and 99.8%, respectively. Electro winning experiments show that the electric energy consumption for electrodeposition of copper is 15.5% lower when the electrolyte is free of impurities.     

Separation of praseodymium(III) from aqueous solutions by nanofiltration

Abstract

The increased demand for rare earth elements in commercial products is increasing their production, which in turn increases public exposure to rare earth elements. The objective of the present work is to study the separation of praseodymium from aqueous solutions by a commercial nanofiltration membrane (NF-300) at various operating conditions. The permeate and feed samples were analysed with inductively coupled plasma atomic emission spectrometry (ICPAES) to find praseodymium [Pr(III)] concentration. The results indicated that the separation of Pr(III) ions increased with increase in applied pressure (2–10 bar) and cross flowrate (4–16 L min^?1); and decreased with increase in feed concentration (10 mg L^?1 PrCl₃ – 100 mg L^?1 PrCl₃). The highest observed separation of the Pr(III) was found to be 89·07 and 84·20% for an initial feed concentration of 10 and 100 mg L^?1 PrCl₃ respectively. It was also observed that separation of Pr(III) increases to 99·28 and 99·30% in complexation step by using ethylene diamine tetra aceticacid (EDTA) and diethylene triamine penta aceticacid (DTPA) respectively, as the chelating agent has generally influenced by pH (2 –10).

La demande accrue d’éléments de terres rares dans les produits commerciaux augmente leur production, ce qui, à son tour, augmente l’exposition du public aux éléments de terres rares. Le but de ce travail est d’étudier la séparation du praséodyme à partir de solutions aqueuses au moyen d’une membrane commerciale de nanofiltration (NF-300) sous diverses conditions d’utilisation. On a analysé les échantillons de perméat et d’apport au moyen de la spectroscopie d’émission atomique avec plasma induit par haute fréquence (ICPAES) afin de déterminer la concentration du praséodyme [Pr(111)]. Les résultats indiquaient que la séparation d’ions de Pr(111) augmentait avec une augmentation de la pression appliquée (2–10 bar) et de la vitesse de l’écoulement transversal (4–16 L min^?1) et diminuait avec une augmentation de la concentration de l’apport (10 mg L^?1 PrCl₃ – 100 mg L^?1 PrCl₃). On a trouvé que la valeur la plus élevée de séparation observée pour le Pr(111) était de 89·07 ou de 84·20% pour une concentration initiale de l’apport de 10 ou de 100 mg L^?1 de PrCl₃, respectivement. On a également observé que la séparation du Pr(111) augmentait jusqu’à 99·28 ou 99·30% dans une étape de complexation en utilisant de l’acide éthylènediaminetétracétique (EDTA) ou de l’acide diéthylènetriamino-pentaacétique (DTPA), respectivement, comme agent chélateur, influencé généralement par le pH (2–10).     

分子识别技术(MRT)在铜精炼中的应用—从铜电解液中除铋

在世界经济中,高纯电解铜是一种重要的商品,主要用来生产铜线。全球冶炼厂处理来自不同产地的矿石,生产出高纯电解铜。这些铜精矿通常含有0.1%的铋。如果最终产品中的铋含量超过2×10^-6,会导致产品出现脆性,使得铜产品不适合用于拉丝生产。IBC先进技术有限公司开发出一种有效的除铋系统,用于分离铜电解液中溶解的铋,使铋含量达到一个理想的水平。该系统与铜生产系统一体化,可实现连续作业。IBC采用一种分子识别技术（MRT）工艺来进行分离作业。在该工艺中,专门设计的螯和剂或配位体与固体骨架（例如硅胶）进行化学结合,产生一种称为SuperLig^的固相系统。这套除铋系统已经用于几家电解厂的铜精炼生产中。本文介绍了从铜电解液中分离和回收铋的工艺步骤,这些工艺步骤包括:吸收、一段洗涤、预解吸、主要解吸、后解吸、二段洗涤、铋沉淀,给出了每个步骤控制和监测的项目。本文讨论了采用其它技术控制铋的局限性。作者还介绍了MRT系统为铜电解厂带来的经济效益,这些铜电解厂都存在铋的问题。     

Computer modelling of the solvent extraction of iron by versatic acid from aluminium nitrate solutions

The development of a chemically based computer model of the extraction of ferric iron from concentrated aluminium nitrate solutions by Versatic 10 is outlined. The model uses previously determined equilibrium constants to calculate the distribution of iron in the various metal complexes present in the organic phase, together with empirical relationships for the pH changes occurring in the aqueous phase during extraction. A mean error of ±13% was found between computer predicted and experimentally determined organic phase iron concentrations for a four-stage counter-current extraction system. It is concluded that iron extraction by Versatic 10 is a technically feasible method of achieving aluminium nitrate with a sufficiently low iron content to enable the production of smelter grade alumina.     

Ethyl-bis-triazinylpyridine (Et-BTP) for the separation of americium(III) from trivalent lanthanides using solvent extraction and supported liquid membrane methods

The present paper deals with the solvent extraction and supported liquid membrane studies on Ln(III)/An(III) separation using ethyl-bis-triazinylpyridine (Et-BTP) as the extractant. The solvent extraction studies involved evaluation of a) diluents, b) phase modifiers, c) stripping agents and d) role of feed acidity. Though reasonably high separation factor values were obtained when Et-BTP was used along with α-bromo carboxylic acids, the mixtures could not be used for liquid membrane studies due to unsatisfactory stripping. On the other hand, a combination of Et-BTP with chlorinated cobalt dicarbollide (CCD) in nitrobenzene resulted in significant Am(III) mass transfer when used in the solvent extraction as well as SLM studies. Improved transport, membrane stability, and decontamination from lanthanides were observed when the organic phase diluent composition was 60% nitrobenzene + 40% n-dodecane. Using 0.02 M Et-BTP along with 0.005 M CCD in 60% nitrobenzene + 40% n-dodecane, the SLM studies on a mixture of ²⁴¹Am, ¹⁵²Eu and ¹⁴⁷Nd in a feed containing 0.1 M HNO₃, indicated quantitative Am³⁺ transport in 3.5 h with co-transport of about 8% Nd³⁺ and 22% Eu³⁺.     

Improvement of the technology of iron removal from electrolyte solutions in nonferrous Metallurgy

An improved variant for the purification of a nickel electrolyte from iron has been developed. According to the flow chart proposed for purification, copper is first extracted by carburization with nickel and iron hydroxide then precipitates upon the introduction of nickel carbonate and oxidation with air oxygen. The iron hydroxide is subjected to conversion into ferrisulfite with the thermal hydrolysis of a suspension and the filtration and washing of the hydrolyzate and to heat treatment to obtain pigment iron(III) oxide.     

Solvent extraction of gallium(III) from sodium hydroxide solution by alkylated hydroxyquinoline

The distribution equilibria and kinetics of the extraction of gallium(III) from sodium hydroxide solutions by 7-(5,5,7,7-tetramethyl-locten-3-yl)-8-hydroxyquinoline (Kelex 100, designated HQ in the following) in kerosene have been examined under various conditions. From the dependence of the distribution coefficient on the concentrations of aqueous hydroxide and Kelex 100 it is deduced that the extraction can be expressed as Ga(OH)⁻₄(a) + 3 HQ(o) ⇄ GaQ₃(a) + OH⁻(a) + 3 H₂ O(a). Furthermore, the kinetic results suggest that gallium(III) is taken up through the formation of either of two different activated species, Na⁺[Ga(OH)₃ ], OH⁻ and Na⁺ · Na⁺[Ga(OH)₃], depending on the concentration of sodium hydroxide in the aqueous phase.     

Recovery of Al(III) and Fe(III) from mixed chloride solutions containing platinum(IV)

The sorption of Fe(III), Al(III) and Pt(IV) from the individual and mixed chloride solution was investigated by using PC88A resin. With the increase of HCl concentration to 5 M, the distribution coefficient of Fe decreased slowly, while that of Al decreased rapidly and the distribution coefficient of Pt was nearly zero in our experimental range. Batch experiments showed that it was possible to extract both Fe and Al simultaneously by adjusting HCl and PC88A resin concentrations. However, continuous extraction chromatographic experiments indicated that simultaneous sorption of Al as well as Fe was difficult in our experimental range. Two extraction chromatographic steps would extract most of Fe and 90% of Al from the mixed solution, while Pt was not extracted. Extraction chromatography of the mixed chloride solution with PC88A resin was found to be fast and simple.     

Synergistic extraction of iron(III) at higher concentrations in D2EHPA-TBP mixed solvent systems

The extraction of iron(III) from chloride solutions at macrolevel concentration by different solvents such as tri-n-butyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA), and their mixture in various proportions has been investigated at different acid concentrations. The synergistic extraction of iron(III) with a mixture of TBP and D2EHPA was studied and the results were compared with that of the extraction by individual solvent alone. An increase in the concentration of the synergist, TBP, in the D2EHPA-TBP solvent system resulted in an increase in the synergistic co-efficient value. The experimental data are treated graphically to explain the formation of organic phase extracted species, and the equilibrium extraction constants for the species are determined. It is found that a maximum of two molecules of TBP are adducted to the extracted species of the corresponding nonsynergistic system. Stripping of iron(III) with hydrochloric acid from loaded D2EHPA was found to increase with an increase in acid concentration. In the case of D2EHPA-TBP mixtures, stripping efficiency was increased with an increase in acid concentration up to a certain level and then it was decreased. The experimental results indicate that an iron exchange reaction between loaded D2EHPA and TBP proceeds during stripping at a higher concentration of hydrochloric acid (from mixed loaded solvent system). A plausible mechanism for iron(III) extraction and stripping has been discussed.     

溶剂萃取法从含钒浸出液中提钒的研究进展

提钒原料、浸出工艺及浸出条件等将决定浸出液中钒的存在形态及净化方法.溶剂萃取法可有效净化回收浸出液中的钒,具有处理量大、选择性高、可回收利用、产品纯度高等优点,在钒冶金中得到越来越广泛的应用.笔者针对不同提钒原料所得到的含钒浸出液,综述了各类萃取剂以一定萃取机制从中萃取钒的研究现状.讨论了萃取过程中溶液pH值、协萃剂、萃取时间、杂质元素及萃取预处理等因素对钒萃取分离的影响,并介绍了溶剂萃取法从含钒浸出液中提钒新技术,提出了钒溶剂萃取技术的未来发展方向.      

The extraction of copper(II) and iron(III) from chloride and sulphate solutions with LIX 64N in kerosene

A comparison has been made of the extraction of Cu(II) and Fe(III) from chloride and sulphate solutions with LIX 64N in kerosene. The effects on extraction of pH, anion concentration, and temperature were examined, and attention was paid to the ionic strength of the aqueous media, some of which contained aluminium and magnesium; extraction was carried out under ‘practical’ rather than ‘ideal’ conditions. Extraction of both Cu and Fe was enhanced from chloride solutions compared with sulphate; although separation of Cu from Fe was slightly reduced, extraction of Cu from chloride liquors appears to be applicable to commercial leach solutions.     

Recommended nomenclature for solvent extraction (liquid-liquid distribution)

Recommendations are presented for nomenclature in solvent extraction chemistry and processes including definitions, preferred symbols, and comments on the acceptability or otherwise of certain terms and their use in particular situations. An attempt has been made to generalize the definitions to include any system of two immiscible liquid phases.     

Efficient extraction and stripping of Nd(III), Eu(III) and Er(III) by membrane dispersion micro-extractors

The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and low efficiency if operated at the above condition. Membrane dispersion micro-extractor, owing to its well-dispersed, high surface-to-volume ratio and fast mass transfer rate, was employed in our work. Nd(III), Eu(III), Er(III) were chosen to represent light, medium, heavy rare earth elements (REEs). The extraction process of REEs with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) was investigated by membrane dispersion micro-extractors. Firstly, the extraction equilibrium of these three elements was explored in the stirred conical flasks, and it is indicated that the extraction efficiencies can be 0.95, 0.97 and 0.98, respectively within 40 min at phase ratio of 100:1. Then the effects of operational conditions such as the residence time, organic and aqueous flow rates on extraction efficiency were also explored in micro-extractors. The results indicate that the efficiency decreases and then increases if increasing aqueous phase flow rate, residence time and droplets' diameter are the key factors of this process. Increasing the phase ratio reduces the extraction efficiency significantly. When the REEs solution has an initial pH of 4.00, the flow rates of continuous and dispersed phase are 40 and 1.6 mL/min, respectively, and 90 mg/L Nd (III), Eu(III) and Er(III) is extracted by 1 mol/L P507 at the out-let length of 8 m. The extraction efficiencies are 0.978, 0.983 and 0.991, respectively. Finally the stripping process was also studied with the micro-extractor. The stripping efficiencies of Nd(III), Eu(III) and Er(III) can reach 0.99, 0.96 and 0.91, respectively when the out-let length is 8 m and the concentration of hydrochloric acid is 1 mol/L. The developed approach offers a novel and simple strategy on the fast extraction and enrichment of low concentration rare earth elements from waste water.     

Determination of organic phase complexes formed on extraction of iron(III) from aluminium nitrate solutions with versatic 10

The extraction of Fe(III) from concentrated aluminium nitrate solutions by Versatic 10 in Escaid 110 was studied, using an AKUFVE system for the determination of extraction isotherms at constant pH values. The extraction data were analysed initially by classical slope analysis but this was found to be inadequate due to the complexity of the organic phase speciation. A statistical technique was then used to evaluate the compositions of the organic phase complexes by finding the best fits to the extraction data. Equilibrium constants governing the extraction of these complexes were calculated. Independent measurements of the amount of Versatic acid bound in the organic iron complexes were made by quantitative infrared analysis of organic extracts. Agreement between the statistical and infrared results was good. Complexes of the general form (Fe(OH)_3? V_n·sHV)_x were found, where n varied from 1 to 2 and s from about 0.5 to 2.5, with both decreasing as the iron loading in the organic phase was increased. Values of 2 or 3 were generally found for x, indicating the predominance of dimers and trimers.