British Nuclear Fuels Plc

Idaho Research Foundation, Inc.

Neil Graham Smart

Chien M Wai

Yuehe Lin

Igor V Smirnov

Nigel Dennis Tinker

Timothy Nicholas Milner

Robert George Holmes

Alexander Hamilton Smith

Anthony Alan Clifford

Cindy Phelps

Mark D Burford

Michael Darbyshire

Andrey Y Shadrin

Vassily A Babain

Fred H Hunt

Catherine M Cowey

Andrey A Murzin

Vadim A Starchenko

Keith D Bartle

Metal ions are removed from solid surfaces which may be contaminated with one or more radionuclides by contacting the solid surfaces with the supercritical fluid, as, for instance, carbon dioxide containing both an acidic ligand and organic amine. The metal ions are extracted from the solid surface and the extract is separated from the solid surface.

Method for removing inorganic matter from solid surfaces

A method for separating a desired metal or metalloi from impurities using a supercritical extraction process based on solubility differences between the components, as well as the ability to vary the solvent power of the supercritical fluid, is described. The use of adduct-forming agents, such as phosphorous-containing ligands, to separate metal or metalloid chelates in such processes is further disclosed. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of &bgr;-diketones; phosphine oxides, such as trialkylphosphine oxides, triarylphosphine oxides and alkylarylphosphine oxides; phosphinic acids; carboxylic acids; phosphates, such as trialkylphosphates, triarylphosphates and alkylarylphosphates; crown ethers; dithiocarbamates; phosphine sulfides; phosphorothioic acids; thiophosphinic acids; halogenated analogs of these chelating agents; and mixtures of these chelating agents. In especially preferred embodiments, at least one of the chelating agents is fluorinated.

Method for separating metal chelates from other materials based on solubilities in supercritical fluids

A process for the decontamination of radioactively contaminated metal which comprises contacting the metal with a decontamination reagent solution containing an organic acid and an oxidising agent, allowing said solution to react with the contaminated metal at a pH of up to 4.5, treating the resulting solution to cause substantially complete precipitation of dissolved metal together with radionuclides and separating precipitated material, containing radioactive contaminants, from said solution.

Decontamination of metal

A method for dissociating metal-ligand complexes in a supercritical fluid by treating the metal-ligand complex with heat and/or reducing or oxidizing agents is described. Once the metal-ligand complex is dissociated, the resulting metal and/or metal oxide form fine particles of substantially uniform size. In preferred embodiments, the solvent is supercritical carbon dioxide and the ligand is a .beta.-diketone such as hexafluoroacetylacetone or dibutyldiacetate. In other preferred embodiments, the metals in the metal-ligand complex are copper, silver, gold, tungsten, titanium, tantalum, tin, or mixtures thereof. In preferred embodiments, the reducing agent is hydrogen. The method provides an efficient process for dissociating metal-ligand complexes and produces easily-collected metal particles free from hydrocarbon solvent impurities. The ligand and the supercritical fluid can be regenerated to provide an economic, efficient process.

Method and apparatus for dissociating metals from metal compounds

Solvent extraction

Solvent extraction of metal containing species

A method of separating a solute from a supercritical fluid which includes reducing the pressure of the supercritical fluid and is characterized in that the supercritical fluid and solute are mixed with another fluid, eg an inorganic or organic solvent under pressure, to cause a partial reduction in the pressure of the supercritical fluid followed by reduction of the pressure of the fluid mixture comprising the supercritical fluid and said other fluid. The fluid mixture pressure reduction may occur in a collection device. Such a device may have a collection solvent already present therein. The said other fluid used partially to depressurise the supercritical fluid may act as a collection solvent in a collection device. The collection device may include one or more collection vessels or alternatively a solid phase trap or a packed column for the purpose of trapping and collecting the solute.

Separating solutes from solutions

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Workington, United Kingdom

Neil Graham Smart