New Environment-Friendly Approach for Bastnasite Metallurgic Treatment (I): Extraction of Tetravalent Cerium from Sulphuric Acid Medium with Di(2-ethylhexyl) Phosphoric Acid

Bastnasiteisamainsourceofrareearthproducts inwhichCeO2/REOisabout50%.Atpresent,a cidity leachingcombinedwithalkali conversion method[1]iscommonlyusedinthebastnasitetreat ment.Thismethodisunfriendlytotheenvironment becausetheradioactiveelementofthoriuman…     

核燃料循环中所用含磷萃取剂的辐照稳定性研究

对核燃料后处理以及高放废液处理中所用的含磷萃取剂的辐照稳定性已经进行了广泛的研究。对正辛基苯基-N，N’-二异丁基胺甲酰甲基氧化膦(CMPO)、二(2-乙基己基)磷酸(DEHPA)以及混合三烷基氧化膦(TRPO)等的辐照稳定性的研究进行了综述。主要介绍了CMPO、DEHPA和TRPO的辐解产物；辐照对萃取和保留的影响以及辐照后溶剂的净化方法。     

Cobalt removal from waste‐water by means of supported liquid membranes

BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste‐water. In the present work, the removal of Co(II) from a synthetic CoSO₄ solution containing initial amounts of cobalt(II) in the range 100–200 ppm (0.1–0.2 g dm^?3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di‐2‐ethyl‐hexylphosphoric acid (D2EHPA) and 5‐dodecylsalicylaldoxime (LIX 860‐I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid–liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui‐Cel Extra‐Flow 4 × 28) having a surface area of 19 m², a steady Co(II) flux of 0.140 gm^?2h^?1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm^?3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860‐I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry     

Adsorption studies of Cr(III) ions from aqueous solutions by DEHPA impregnated onto Amberlite XAD7 – Factorial design analysis

The present paper investigates the adsorption of Cr(III) ions using the SIR, prepared by impregnation of Amberlite XAD7 with di-(2-ethylhexyl)-phosphoric acid (DEHPA), which has been chosen as an extractant for the purpose of this study. The Amberlite XAD7–DEHPA resin was impregnated with DEHPA and ethylic alcohol as solvent trough dynamic column impregnation method. The influence of different physicochemical parameters (pH, resin dosage, initial concentration of Cr(III) ions, contact time and temperature) upon the adsorption capacity of XAD7–DEHPA, in the Cr(III) ions removal process from aqueous solution, has been investigated. The pH for Cr(III) ions adsorption was found as 3.0 for this material. The results showed that the adsorption equilibrium was reached after 45 min. The adsorption process is best described by the pseudo-second order kinetic model. Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The maximum adsorption capacity is ∼3 mg Cr(III) ions/g SIR. The thermodynamic studies allowed us to determine the thermodynamic parameters ΔG°, ΔH° and ΔS°. In this paper the factorial design of experiments was used to study the performance of the adsorption process.     

从硫酸盐溶液中协同萃取镓

A novel extractant mixture, di-2-ethylhexyl phosphate (DEHPA) plus HX, was proposed and tested for recovering gallium from sulfate solution. It was found that the extraction capacity of DEPHA for gallium from sulfate solution could be enhanced significantly due to the synergistic effect of acidic extractant HX. Gallium extraction is negligible below pH 0 and highly sensitive to pH of aqueous phase in the range from 0 to 1, and satisfactory extraction can be gained at pH＞1. More than 96% Ga extraction was obtained using 15% DEHPA plus 2% HX. Although Fe (Ⅲ) was found to be extracted preferentially to Ga (Ⅲ), effective extraction of Ga (Ⅲ) was possible by reducing ferric to the ferrous state prior to extraction. A loaded organic phase containing 0.48g. L-1 Ga could be produced from solution of 0.12g@L-1 Ga at A/O ratio of 4: 1 via three mixer-settler operation stages.Gallium was stripped quantitatively from the loaded organic phase with 1.5 mol@L-1 of sulfuric acid.     

Uranium extraction from partially neutralised and diluted phosphoric acid using a synergistic organophosphorous solvent mixture

A process is described for the separation of uranium from partially neutralised and diluted phosphoric acid (PNDA) which is generated in fertiliser plants when phosphoric acid is used to scrub ammoniacal vapours from the neutralisation reactors. The separation process is based on solvent extraction using a synergistic mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) with tri-n-alkyl phosphine oxide (TAPO). The effects of process parameters including concentration of DEHPA and TAPO, temperature and degree of neutralisation of acid have been investigated. Laboratory scale and pilot plant scale tests have been carried out. The extraction reaction is found to be exothermic with enthalpy effect of 30 kJ/mol. Tests on stripping of extracted uranium and recovery of uranium have been carried out and results are reported. Analysis of data indicates significant differences in the mechanism of uranium extraction from PNDA and the mechanism reported in literature for extraction of uranium from weak phosphoric acid using a similar solvent mixture.     

Separation of Cadmium,Cobalt, and Nickel by Solvent Extraction using the Nickel Salts of the Extractants

A new solvent‐extraction process for the separation of cadmium, cobalt, and nickel in sulphate solutions coming from the hydrometallurgical processing of spent Ni‐Cd batteries is proposed. The main innovation is to use nickel salts of the extractants, thus avoiding external pH control in the extraction operation. The extractants are first loaded with nickel in conditioning steps, using a neutralizer for pH control, and afterwards contacted with the aqueous processing solutions for extraction of interested metals with no further need of neutralization. This process is an alternative to the usual approach, which uses the sodium or ammonium salts of the extractants, avoiding introducing these cations in the process stream. Using this approach, the extraction of cadmium with nickel salt of 1 M DEHPA was performed at resulting pH values of 3.8–4.3 producing an organic phase loaded with 35 g/L Cd. Cobalt extraction with the nickel salt of Cyanex 272 was further achieved at resulting pH of 5.1–5.7 obtaining a organic loaded with 6.5 g/L Co.     

The Metals Industries in the Eighties: A Preface to the Arden House Conference∗

The changing nature of the world metals industry was the subject of a three-day meeting of experts from around the world. The conference, held in May, 1986 and sponsored by the United States Bureau of Mines and the Henry Krumb School of Mines of Columbia University, included sessions on: the current status of the industries; changes in metals demand; changes in metals supply and trade; implications for the private sector; and implications for the public sector. The article introduces the issues raised at the Arden House Conference.     

有机磷(膦)酸对碱土金属的萃取

Solvent extraction equiliria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester, di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent of the e/r value and hydration energy of the metal ions. The minor shift of the P→O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P→O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compunds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effects is explained by using IR spectra of the loaded organic phase.     

Solvent Extraction Studies for Separation of Zn(II) and Mn(II) from Spent Batteries Leach Solutions

This study aims at assessing the possibility of using solvent extraction processes for separating Zn(II) and Mn(II) dissolved in aqueous solutions obtained by acid bioleaching of spent alkaline and Zn-C batteries. In this context, Cyanex 272 and DEHPA were tested as extractant agents, and the former was shown to have better performance. Hence, the effect of four factors (equilibrium pH, extractant concentration, A/O ratio, and temperature) into three response variables (extraction efficiency of Zn, Y_Zn; extraction efficiency of Mn, Y_Mn; separation factor, β) were tested according to a full factorial design (2⁴) with two replicated center points. Our study revealed that Y_Zn depends mainly on the extractant concentration, Y_Mn on the equilibrium pH and β on the equilibrium pH, extractant concentration, and A/O ratio as well as on second and third order interactions. One extraction step is sufficient to reach high extraction of zinc in synthetic solutions, but two stages were required for real leaching liquor. The extraction kinetics is fast (less than 15 min) for both metals, even when real liquor was tested. The organic solvent can be efficiently recovered using a stripping solution of H₂SO₄ 1 M and thus the process can be considered environmentally sustainable.