Abstract: The invention relates to a method of manufacturing permeable mineral membranes.The method of the invention is characterized in that a thin layer of gel of peptised hydroxide of at least aluminum is deposited on a permeable perous substrate and the resulting membrane is dried and fired at a temperature between 500.degree. and 1100.degree. C.The resulting membranes can be used for isotopic separation of gases or for filtration and ultrafiltration.

Abstract: The invention relates to a process for the production of porous, permeable, mineral membranes.According to this process, on a porous, permeable substrate is formed a thin layer of at least one mineral compound chosen from among the simple or mixed metal oxides, except aluminum oxide and mixed aluminium oxides, simple or mixed metal hydroxides, except aluminium hydroxide and mixed aluminium hydroxides and mixtures thereof on the basis of a suspension in a liquid of colloidal or non-colloidal particles, said compound or a precursor thereof having particle sizes below 10 .mu.m. The suspension is kept in the finely divided state by the continuous application of energy to the reaction medium. The thus obtained membrane is dried and then annealed at a temperature between 400.degree. and 1100.degree. C.The use of a suspension of ultrafine colloidal or non-colloidal particles makes it possible to obviate the compression stage and obtain microporous layers with very small pore radii.

Abstract: An apparatus and process are disclosed for separation of isotopes by gaseous diffusion. The apparatus comprises at least one assembly of microporous capillary tubes having a hydraulic diameter below 0.5 cm, an average pore radius below 200 .ANG., a thickness between 20 and 500 microns, a length of at least 25 cm, a porosity between 10 and 60% and a permeability to air between 10.10.sup.-7 and 100.10.sup.-7 mole/cm/.sup.2 /min/cm of mercury. The tubes are made from an inorganic material and have a circular, square or rectangualr cross-section.

Abstract: The invention relates to a support for a ceramic porous barrier of the kind used for obtaining a concentration of uranium 235 in uranium hexafluoride by ultrafiltration. The support is formed by superposing a number of layers in the form of pastes, the particle size being homogeneous and constant in each layer and decreasing from the outer towards the inner layers. The pastes are prepared from powdered materials such as metals, oxides, silicates, borides, nitrides and halides to which mineral binders are added. The pastes are simultaneously extruded or co-extruded after which the resulting support is baked.