Abstract: A process and installation for the separation of heavy and light compounds is provided. According to the process, a solid or liquid phase containing the compounds to be separated is contacted with a supercritical fluid in an extractor, after which the supercritical fluid containing compounds leaving the extractor undergo nanofiltration for recovering a permeate flow containing the light compounds and a retentate flow containing the heavy compounds. The invention has particular utility for separating fats in food stuffs such as butter or fish oil.

Abstract: A process for the treatment of products constituted by hides and skins with a view towards their transformation into leather, and for the treatment of leather which involves contacting the product with a dense, pressurized fluid, such as CO.sub.2, in the supercritical state or pressurized liquid, which optionally contains one or more active substances and a specified pressure Pi and temperature Ti, in order to provide degreasing of the skins if pure dense fluid is used, or to impregnate the products with active substances such as tanning, stiffening, dyeing or waterproofing agents. The products are subsesquently brought to atmospheric pressure to eliminate the dense fluid therefrom.

Abstract: The invention relates to a reverse osmosis or nanofiltration membrane and to its production process. This membrane comprises a porous support made from an inorganic material coated on one face with a first mesoporous inorganic material layer, e.g. of TiO.sub.2, having a mean pore radius below 10 nm and a second active layer, having a thickness of 0.1 to 1 .mu.m, made from sulphonated polysulphone, polybenzimidazolone, grafted polyvinylidine fluoride or Nafion..RTM.

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: 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.

Abstract: A chemical process of isotopic enrichment of uranium makes use of isotopic exchange between an aqueous phase loaded with uranium III and another phase charged with uranium IV. Reduction and oxidation of uranium in aqueous phase are carried out using the same electrolyzer. Reduction may be by zinc amalgam which is later electrolytically reduced.