Abstract: An apparatus for the extraction of constituents present in a substance by means of an extraction fluid constituted by a supercritical fluid or a pressurized liquid. According to this apparatus, in an exterior (3) contacting takes place between the substance and the extraction fluid in order to dissolve the constituents in fluid. The fluid leaving the extractor is then treated to separate the extracted constituents. The fluid is expanded at a pressure p.sub.1. Firstly, the less volatile constituents are separated in a liquid-gas separator (41), the separated gas is then liquefied in gas separator-liquefier (13) and the thus liquefied gas is rectified in column (19) to concentrate the extracted constituents in the liquid phase. The extraction fluid can be carbon dioxide gas.

Abstract: Liquid-liquid exchanger where a dispersed phase circulates also in a continuous phase, wherein an electrocoalescer is placed in that part of the exchanger located between the dispersed phase inlet and the continuous phase outlet.Application to the separation of uranium isotopes by chemical exchange.

Abstract: A process for the purification of uranium hexafluoride containing traces of neptunium fluoride and/or plutonium fluoride, wherein the uranium hexafluoride to be purified is contacted with a metal fluoride chosen from the group including lead fluoride PbF.sub.2, uranium fluorides of UF.sub.4+x in which x has a value between 0 and 1 and chromium trifluoride CrF.sub.3, at a temperature such that the plutonium and/or neptunium fluorides are reduced, and wherein the thus purified uranium hexafluoride is recovered.