Abstract: An apparatus (1) for thermal denitration of a uranyl nitrate hydrate to uranium trioxide UO3. The apparatus (1) comprises a burner (114) and a reaction chamber (110) configured to carry out thermal denitration of uranyl nitrate hydrate and to form uranium trioxide UO3 in the form of particles. The apparatus also comprises a separating chamber (120) suitable for separating UO3 particles from the gases resulting from the thermal denitration carried out in the reaction chamber (110), and at least one filter (130) configured for purifying the gases. The separating chamber (120) is a decanting chamber into which the reaction chamber (110) directly opens out. The filter (130) is capable of performing the separation at a temperature greater than or equal to 350° C. The invention also relates to use of such an apparatus, to a thermal denitration process and to UO3 particles obtained by such a process.

Abstract: An apparatus (1) for thermal denitration of a uranyl nitrate hydrate to uranium trioxide UO3. The apparatus (1) comprises a burner (114) and a reaction chamber (110) configured to carry out thermal denitration of uranyl nitrate hydrate and to form uranium trioxide UO3 in the form of particles. The apparatus also comprises a separating chamber (120) suitable for separating UO3 particles from the gases resulting from the thermal denitration carried out in the reaction chamber (110), and at least one filter (130) configured for purifying the gases. The separating chamber (120) is a decanting chamber into which the reaction chamber (110) directly opens out. The filter (130) is capable of performing the separation at a temperature greater than or equal to 350° C. The invention also relates to use of such an apparatus, to a thermal denitration process and to UO3 particles obtained by such a process.

Abstract: The invention relates to a silicon carbide or metal carbide foam to be used as a catalyst or catalyst support for the chemical or petrochemical industry or for silencers, as well as the process for producing the same. The foam is in the form of a three-dimensional network of interconnected cages, whose edge length is between 50 and 500 micrometres, whose density is between 0.03 and 0.1 g/cm3 and whose BET surface is between 20 and 100 m2/g. The carbide foam contains no more than 0.1% by weight residual metal and the size of the carbide crystallites is between 40 and 400 Angstroms. The production process consists of starting with a carbon foam, increasing its specific surface by an activation treatment using carbon dioxide and then contacting the thus activated foam with a volatile compound of the metal, whose carbide it is wished to obtain.

Abstract: A process for the production of a metal carbide having a BET specific surface area of 10 to 200 m.sup.2 /g, in which a reaction mixture including carbon having a specific surface area of at least 200 m.sup.2 /g and a compound of the metal to be reacted with the carbon which is volatile at 900.degree. C. to 1400.degree. C. is introduced into a reactor, the reactor is scavenged by a flow of inert gas and the reaction mixture is heated under the flow of inert gas at 900.degree. to 1400.degree. C. for a time sufficient to volatilize the metal, reduce the volatilized metal compound to the metal with and carburize the metal by reaction with carbon, forming the metal carbide. The metal carbide formed is cooled under the flow of inert gas.

Abstract: An industrial process for the obtaining, preferably without casting, of its of high-purity master alloy based on at least one rare earth and at least one transition metal by metallothermic reduction of a compound of said rare earth by means of a reducing agent such as alkali or alkaline earth metals, characterized in that the transition metal is introduced into the starting reaction mixture, at least in part in the form of a compound which can be reduced by the reducing agent used.