摘要:

The current state-of-the-art is design and scale-up procedures for column-type liquid-liquid extractors is reviewed. This covers both the hydrodynamical factors which determine column cross-section and throughput, and those which influence mass transfer via drop-size and holdup, mass transfer coefficient, axial dispersion, drop interactions (i.e., breakage and coalescence), and Marangoni effects. The application of these principles to column design and scale-up is then discussed. It is concluded that for the present, both a matrix inversion method, and a simplified analytical method of adequate accuracy both for performance evaluation from pilot scale data, and for the design of both single-solvent and dual-solvent extractors, are the most suitable. Finally, the possibility is considered of developing more advanced methods based both on Monte Carlo procedures and on direct dynamic simulation by computer.

ISSN:0882-7508    

DOI:10.1080/08827509808914158

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The systems Ca(II)-As(III)-H2O and Ca(II)-As(V)-H2O were studied by equilibrating mixtures of calcium oxide and arsenious or arsenic acid solution at 25°C for one month. Where the pH of the final solution was likely to be greater than 8, care was taken to exclude atmospheric carbon dioxide. Chemical analysis of the final solid phases and the associated solution from each experiment for calcium and arsenic, together with X-ray diffraction analysis of the solids and an inspection of graphed relationships, indicated the existence of the compounds Ca(AsO2)2and CaAsO2OH 1/2H2O in the system Ca(II)-As(III)-H2O; and Ca(H2AsO4)2, CaHAsO4H2O, Ca3(AsO4)24H20 and Ca2AsO4OH 2H2O in the system Ca(II)-As(V)-H2O. The solubility and stability regions for these compounds were assessed as a function of pH, and solubility constants and conditional free energies of formation for each compound calculated from the solubility data obtained.

ISSN:0882-7508    

DOI:10.1080/08827509808914159

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Tri-n-Butyl Phosphate has been found to be an extractant-par-excellence for nuclear fuel reprocessing. It has a unique combination of physical and chemical proerties and is commercially available at relatively low cost. However, the other homologues of TBP-with branched alkyl chains as well as linear alkyl chains-do possess advantages for specific applications that merit attention. Thus, a relative comparison of the extraction properties of the trialkyl phosphates is rewarding, both from a fundamental as well as technological point of view. The present review attempts to survey the data reported and the understanding generated on the extraction of actinides by trialkyl phosphates, with an emphasis on the elements U, Th and Pu, taking into account their importance derived from their primary role in the nuclear fuel cycles. While reviewing the data, emphasis is placed on data measured for extraction by 1.09 M solution of the extrac-tant, from nitric acid medium.

ISSN:0882-7508    

DOI:10.1080/08827509808914160

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Liquid surfactant membranes, noted as a novel separation technique, have potential applications in many fields, especially in extractive metallurgy. High separation efficiency with the membranes can be achieved by using type I and type II facilitated transport mechanisms to maximize both the flux through the membranes and the capacity of the internal receiving phase for the diffusing species. Mass transfer models for both facilitated transport mechanisms are developed by taking into account the mass transfer and the reactions both inside and outside the emulsion globules, and perturbation solutions to the resulting nonlinear equations are presented. A Carrier Facilitated Transport Factor, defined as the ratio of the extraction rate constant for type II facilitation to that of type I facilitation, is proposed to account for the effect of carriers in the membrane on the extraction rate. Model predictions are in good agreement with the experimental data on batch extraction of acetic acid and auric chloride from their respective aqueous solutions.

ISSN:0882-7508    

DOI:10.1080/08827509808914161

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Extractants and processes used and proposed for recovery of arsenic, antimony and bismuth from copper electrolytes are presented and discussed. The use of the following extractants is duscussed: tributyl phosphate, partial esters of phosphoric acid (mono(2-ehtylhexyl)phosphoric acid, bis(2-ethylhexyl)phosphoric acid and mono(isooctadecyl) phosphoric acid, - DS 5834), esters of alkylphosphonic acids, trialkylphosphine oxide, CYANEX® 923 extractant, hydroxamic acids, LIX 1104, alcohols (2-ethyIhexanol and others), hydrophobic diols and alkylpolyphenols. The chemistry and processes are presented and discussed.

ISSN:0882-7508    

DOI:10.1080/08827509808914162

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor