摘要:

The U.S. Bureau of Mines investigated solvent extraction methods for recovering germanium from sulfuric acid leach filtrates. A new organic extractant system was developed which synergistically and selectively recovered germanium from these solutions. A continuous solvent extraction circuit was operated for over 150 hr, extracting over 90% of the germanium from 0.30 g/L Ge filtrates containing 40 to 60 g/L free acid. Over 90% of the loaded germanium was stripped from the organic phase with water at 75 °C. A section on germanium and gallium co-extraction is also presented.

ISSN:0736-6299    

DOI:10.1080/07366299108918060

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The synergic extraction of Ni from ammoniacal sulfate solution by mixtures of LIX 64N and Kelex 100 was studied using slope analysis, continuous variation, and mathematical modeling. This extractant pair was discovered as part of a study to find extractants that perform •at the higher pH level needed for leaching Cu, Ni, and Co, and thus eliminate ammonia stripping/recharging steps in current processes. Ni was more efficiently extracted at higher pH with the LIX 64N/Kelex mixture than with either extractant alone. A model is proposed based on four different stoichiometrics, each contributing to the overall reaction. Those four Ni/LIX 64N/ Kelex species are 1/2/0, 1/0/3, 1/1/1, and 1/2/1. Ammonia is coextracted, but can be selectively scrubbed with 2 g/L H2S04Ni can be selectively stripped from the Ni- and Cu-loaded extractants with 10 g/L H2S04then Cu is stripped with 150 g/L H2S04A continuous process was simulated with a batchwise circuit, which showed no loss of extraction efficiency in 10 cycles.

ISSN:0736-6299    

DOI:10.1080/07366299108918061

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The tertiary amine extractants N,N,N’,N’-tetra-n-octylethylenediamine, N,N-di-n-octyl-2-(aminomethyl)pyridine and Alamine 336 were used to extract cobalt(II) from a thiocyanate medium. The extraction equilibria were identified and the extraction constants for these equilibria are presented.

ISSN:0736-6299    

DOI:10.1080/07366299108918062

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The extraction of strontium picrate with various open-chain ether dicarboxylie acid diamides, ether dicarboxylie monoamido acids and N-alkyl imino diacetic diamides has been investigated. The influence of pH, diluents and counter anions on the extraction equilibrium was studied. The extraction results are discussed in relation to the structure of the investigated amido podands and compared with crown compounds and open-chain structure analogous. The performed investigations show clearly the amido group is decisive for the extraction properties.

ISSN:0736-6299    

DOI:10.1080/07366299108918063

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The extraction properties of ami do podands 1 - 3_ have been investigated. The ether dicarboxylic acid diamide i shows a clear preference for the extration of rare earth metal ions Yb(III)-, La(III) and the alkaline-earth metal ions Ca(II), Sr(II) as well. Due to the presence of the carboxylic group the ether dicarboxylic acid monoamide, 2. extracts the ions of the 3d-elements Cu(II), Co(II) and Zn(II), too. High distribution ratios have been obtained mainly for soft and medium-hard transition metal ions with the N-alkyl imino diacetic acid diamide 3_. Under the experimentally chosen conditions, alkali metal ions such as Na(I) and K(I) are practically not extracted by the investigated amido podands.

ISSN:0736-6299    

DOI:10.1080/07366299108918064

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The selective distribution of alkaline earth metal ions between carbon tetrachloride and aqueous sodium perchlorate solutions has been investigated by adding chelate forming llgand (thenoyltrifluoroacetone, TTA) and adduct forming llgand (trloctylphosohlne oxide, TOPO) of high concentrations (0.1 M) at 298 K. The separation of alkaline earth metal ions Is explained in terms of their solvent extraction with hydrogen ion in aqueous solutions. The selectivity series, Mg2 +> Ca2 +> Sr2+> Ba2+was established by the solvent extraction method. On the other hand, the selectivity series by the ion-exchange method has been known as Ba2+> Sr2+> Ca2+> Mg2+using crystalline dihydrogen tetratitanate hydrate fibers, H2Ti4O9-nH2O, and aqueous solutions at 298 K. The difference in the two selectivity series is interpreted by the solvation (former) and hydration (latter) effects of metal ions. The values of the separation factors for alkaline earth metal ions given by the combination of the two methods is extremely high, and all probable pairs of these metal Ions can completely be separated.

ISSN:0736-6299    

DOI:10.1080/07366299108918065

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Sal icylaldehyde n-alkanohydrazones (SAAH or H2L) having 1 to 13 carbon atoms in their alkyl chains were synthesized and used for the extraction of some lanthanoid ions (Ln3+) including praseodymium, europium and ytterbium ions from aqueous solutions containing both tri-n-butyIphosphate (TBP) and perchlorate into I,2-dichloroethane The extracted species were (Ln3+) (HL-)2(TBP)3(C101,-) for all SAAH. The partition coefficients, Kd, of SAAH increased with an increase in the carbon number of the alkyl chain, the increment of log Kb being 0.64 per a carbon atom. The acid dissociation constants of SAAH also increased slightly with an increase in the carbon number, but the extraction constants of their lanthanoid complexes were almost independent of the length of the alkyl chain.

ISSN:0736-6299    

DOI:10.1080/07366299108918066

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In electrochemically assisted ion exchange (EIX), a water splitting reaction is used to promote the ion-exchange properties of materials which are incorporated into electrodes. Thus cobalt(II) may be extracted using alpha-zirconium hydrogen phosphate (ZrP) in a matrix of an unreactive polymer in which a platinised titanium electrode is embedded. Although ZrP is an inefficient ion-exchanger under normal (non-assisted ) conditions, EIX promotes the cation exchange behaviour by generation of hydroxyl ions (0H-) at the cathode. There was no observable precipitation of cobalt(II) hydroxide and no plating-out of the cobalt. The process of exchange proceeds entirely by an ion exchange mechanism. There is some base hydrolysis of the ZrP in the vicinity of the cathode, particularly in the first few cycles. Elution may be achieved by reversal of the applied electrical potential in conjunction with a solution pH of less than 2.3. For comparable electrodes, the rate of exchange, using EIX, is significantly greater and the final concentration lower, than is achieved by the use of normal ion exchange.

ISSN:0736-6299    

DOI:10.1080/07366299108918067

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Apple residues (AR) from the cider-making process have been used as a cheap alternative ion exchange polymeric material. These residues were chemically modified in order to increase stability and ion exchange capacity. The ion exchange equilibria of copper, zinc and nickel onto the original residues (AR) as well as onto residues submitted to xanthation and phosphata-tion reactions have been studied. The experimental data fit the Langmuir equation adequately; saturation capacities, distribution constants and separation factors have been calculated.

ISSN:0736-6299    

DOI:10.1080/07366299108918068

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor