Abstract: Hydrocarbons, e.g., ethylene, are steady-state catalytically oxychlorinated into chlorocarbons, e.g., 1,2-dichloroethane, by fluidizing a fluidizable charge by directing a gaseous feedstream containing a hydrocarbon therethrough and therein oxychlorinating such hydrocarbon, the gaseous feedstream further comprising an oxygen-containing gas and gaseous hydrochloric acid and the fluidizable charge comprising immixture of a catalytically effective amount of an oxychlorination catalyst and particles of a catalytically and chemically inert solid substance, and which further comprises introducing a solution or suspension of a catalytically active copper compound into such fluidized charge during the oxychlorination reaction.

Abstract: Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-alumina, well adopted for conversion into refractory bricks or ceramic composites, are prepared by crystallizing a settled fine powder of amorphous alumina, transition alumina or alumina hydrate, advantageously in the presence of a fluoro-compound flux, into a coherent mass of such hexagonal platelets of .alpha.-alumina.

Abstract: Gamma-aluminum oxynitride ground powders, white in color and well suited for conversion into optically transparent ceramic shaped articles, 100% of the particles of which being less than 10 .mu.m in size and exhibiting a transmittance of at least 8%, are prepared by grinding particulate gamma-aluminum oxynitride agglomerates having a porosity of greater than 75%, such agglomerates themselves being produced by interreacting dry powdery admixture of aluminum nitride, alpha-alumina, and an alumina of high specific surface area or precursor thereof.

Abstract: The invention relates to a continuous process for the preparation of aluminum nitride by the carbonitriding of alumina. According to this process, a reaction that uses alumina, carbon, and a resin that generates carbon by pyrolysis is performed in a methodical reactor. The invention relates to a continuous process for the preparation of aluminum nitride by the carbonitriding of alumina.

Abstract: The present invention relates to a new process for the manufacture of fine powder of silicon nitride, to this powder and to the sinters obtained from the latter. The process comprises the reaction, in a nitrogen countercurrent and in continuous fashion, of silica, carbon and a seed crystal, in the presence of a volatile compound of a metal chosen from the group consisting of Be, Mg, Ca, Sr, Ge, Sn, Ti, Hf, Na and Ba, in a reaction zone possessing a temperature gradient, comprising a hot zone in which the said metal compound passes into the gaseous state and a cold zone in which the said metal compound in the gaseous state condenses, the said metal compound in the gaseous state being carried from the hot zone to the cold zone by the nitrogen countercurrent.

Abstract: Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-alumina, well adopted for conversion into refractory bricks or ceramic composites, are prepared by crystallizing a settled fine powder of amorphous alumina, transition alumina or alumina hydrate, advantageously in the presence of a fluoro-compound flux, into a coherent mass of such hexagonal platelets of .alpha.-alumina.

Abstract: Aluminum nitride (AlN) is continuously produced by continuously carbonitriding a continuously replenished charge of alumina, for example successive charges of alumina/carbon extrudates, in a reaction zone comprising at least one conduit, the ratio of the exchange surface area/volume of which at least one conduit ranging from 5 to 50 m.sup.-1, preferably from 10 to 50 m.sup.-1, and continuously withdrawing product AlN therefrom.

Abstract: The invention relates to a continuous process for the preparation of aluminium nitride by the carbonitriding of alumina.According to this process, the reaction, which employs alumina, carbon and nitrogen, is carried out in a moving-bed reactor characterized in that the reaction area has a plurality of conduits.

Abstract: Whisker-free particulates of silicon nitride (Si.sub.3 N.sub.4), e.g., spheres, beads, or a variety of other shaped articles exhibiting a regular and controlled particle size, are produced by incorporating a primary reaction mixture of silica and carbon into a porous, carbon-based matrix material, next carbonitriding the composite thus formed, and characteristically eliminating excess carbon from the carbonitrided composite.

Abstract: Macrocrystalline .alpha.-alumina hexagonal platelets, well adapted as reinforcing materials and polishing agents, are prepared by calcining admixture of transition or hydrated alumina and a fluorocompound flux, such fluorocompound flux having a melting point of up to 800.degree. C. and, in the molten state, serving to dissolve the transition/hydrated alumina.

Abstract: Hydrocarbons, e.g., ethylene, are steady-state catalytically oxychlorinated into chlorocarbons, e.g., 1,2-dichloroethane, by fluidizing a fluidizable charge by directing a gaseous feedstream containing a hydrocarbon therethrough and therein oxychlorinating such hydrocarbon, the gaseous feedstream further comprising an oxygen-containing gas and gaseous hydrochloric acid and the fluidizable charge comprising immixture of a catalytically effective amount of an oxychlorination catalyst and particles of a catalytically and chemically inert solid substance, and which further comprises introducing a solution or suspension of a catalytically active copper compound into such fluidized charge during the oxychlorination reaction.

Abstract: A process is disclosed for producing sintered mixed metal oxide nuclear f pellets containing UO.sub.2 and the oxide of at least one other fissionable or rare earth element M, the pellets being directly soluble in nitric acid without nitric acid additive or prior treatment of the pellets. The process comprises the steps of mixing together nitrate solutions of the elements, concentrating the mixture of solutions, thermally denitrating the concentrated nitrate mixture without additives, to obtain an intermediate mixed oxide powder, calcining the intermediate mixed oxide powder, reducing the calcined mixture, stabilizing the uranium oxide UO.sub.2 in the reduced oxide mixture, shaping and pressing the resulting stabilized, reduced oxide mixture to obtain pellets of green material, sintering the pellets of green material and grinding the sintered pellets.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: Process for the preparation of pulverulent metallic oxides with predetermined reactivity which is adjusted by the specific surface area, which are intended to be subjected to subsequent conversions, by thermal treatment of corresponding nitrates in the form of an aqueous solution or of a solids material, consisting of hydrated uranyl nitrate, on its own or in admixture with at least one of thorium nitrate, cerium nitrate and plutonium nitrate, which process is characterized in that it consists of two treatment stages:(a) the first stage essentially consisting of incompletely dehydrating the hydrated uranyl nitrate.(b) the second stage essentially consisting of decomposing the product resulting from the first stage by calcination under controlled steam pressure.The process is used for obtaining uranium oxide on its own or in admixture with thorium oxide, cerium oxide and plutonium oxide, with a view to subsequent chemical conversions and/or sintering.

Abstract: A process for the production of uranium trioxide having a large specific surface by the thermal denitration of hydrated uranyl nitrate corresponding to the formula UO.sub.2 (NO.sub.3).sub.2 .multidot.xH.sub.2 O, in which 2.ltoreq.x.ltoreq.6, characterized in that, in a first stage, the said nitrate is treated in the form of a liquid at room temperature in the range from 160.degree. C. to 260.degree. C. until a solid phase containing at least 55% by weight of uranium is obtained and, in a second stage, the said solid phase is progressively heated to a temperature of at most 600.degree. C. at a heating rate of at most 1000.degree. C. per hour, and is kept at this temperature of at most 600.degree. C. until a second solid phase of UO.sub.3 having a large specific surface is obtained. The UO.sub.3 product produced has a specific surface of at least 10 m..sup.2 g.sup.-1.

Abstract: Processes for the preparation of pure alumina powders or pure non-stoichiometric alumina-magnesia spinel powders starting with ammonium alum-based compositions which are dehydrated, the dehydration being carried out on dehydrated salts having a bulk density less than 0.2 kg/dm.sup.3 and wherein the dehydration is followed by a calcination with a heating schedule containing at least one intermediate stage at 750.degree. to 850.degree. C., the process of the invention permitting the reproducible production of such aluminas or spinels having specific surfaces of from 100 to 200 m.sup.2 /g and characterized by a very high homogeneity which guarantees a rigorously unimodal pore structure, such aluminas and spinels being useful in preparing isotopic enrichment barriers for gaseous diffusion, as well as metal polishes, catalysts, and catalyst supports.

Abstract: Process for the preparation of high purity alumina containing less than 0.1 weight percent of residual chlorine starting from impure aluminum chloride solutions, which process comprises a crystallization step to provide aluminum chloride hexahydrate crystals having a diameter of from about 400 to about 4000 micrometers in the presence of hydrochloric acid; washing the aluminum chloride hexahydrate crystals so obtained with pure hydrochloric acid; and pyrohydrolyzing the washed crystals of aluminum chloride hexahydrate at a temperature of from about 700.degree. to about 1300.degree. C., in which pyrohydrolysis a gas is forced through a layer of the washed aluminum chloride hexahydrate so as to remove the gaseous reaction products while obviating any possible movement of the solid by the gas, the process particularly producing transition aluminas simultaneously having a specific surface area greater than 100 m.sup.2 /g and a chlorine content less than 0.1 weight percent.

Abstract: Process for preparing high purity aluminas from ammonium alum, the process comprising separately dehydrating the alum and thereafter thermally decomposing the dehydrate, wherein the thermal decomposition is carried out by forcing a gas through a layer of the dehydrated alum so as to continuously remove the gaseous reaction products formed without removal of solids by the carrier gas, and providing improved productivity of high purity transition aluminas having specific surfaces above 125 m.sup.2 /g and/or bulk densities above 0.2 g/cm.sup.3, the transition aluminas so obtained being characterized by their greater reactivity for the preparation of corundum so that corundum having a bulk density greater than 0.4 g/cm.sup.3 can be economically prepared.

Abstract: The present invention relates to an anhydrite binder and to the method of making the same from the gypsum by-product (phosphogypsum) resulting from the production of phosphoric acid by the wet method, said binder comprising particulate anhydrous CaSO.sub.4 with an insoluble CaSO.sub.4 content of at least 93%, an average particle size diameter of 5 to 30, with 15% by weight or more of the particles having a diameter smaller than 10.mu. and 20% by weight or more of the particles having a diameter larger than 20.mu., and a pore volume of less than 0.29cc/g in the case of pores having a radius less than about 6.6.mu..