Abstract: A process for preparing fine aluminium nitride (AlN) powder is described using an inorganic flocculant based on polyaluminium chloride (PAC) having the following structural formula:Al.sub.n (OH).sub.m Cl.sub.3n-mwhere n and m are positive whole numbers and n is greater than m/3.

Abstract: A process for the preparation of monoliths of aerogels of metal oxides, which aerogel is either constituted by one single oxide, or is constituted by a mixture of oxides, is disclosed, which process consists of the following operating steps:(a) the relevant metal alkoxide(s) is/are mixed with water in the presence of a catalyst of acidic character;(b) the so obtained mixture is hydrolysed;(c) a colloidal suspension of the oxide of a metal equal to, or different from, the metal(s) used in the (a) step is added to the hydrolysate;(d) the so obtained colloidal solution is caused to turn into a gel (gelation) having the desired shape and dimensions;(e) the gel is washed;(f) the gel is dried at values of temperature and pressure which are higher than the critical pressure and temperature values of the solvent used for the washing.

Abstract: A method is disclosed for producing solid materials in form of microspheres or spherules for a number of applications, such as nuclear fuel, catalyst, fluid beds for fluidization and other like applications. An inert gas shield is provided to surround the droplets of liquid from which the microspheres shall be originated so as to prevent a premature reaction of such droplets with the reactive gas. Provision is made for renewing the braking foam placed over the liquid reactive bath and the reactive gas is supplied in the form of a blade-like stream so as to improve the contact time and intensity between the droplets and the reactive gas.

Abstract: An apparatus is disclosed for producing solid materials in form of microspheres or spherules for a number of applications, such as nuclear fuel, catalyst, fluid beds for fluidization and other like applications. An inert gas shield is provided to surround the droplets of liquid from which the microspheres shall be originated so as to prevent a premature reaction of such droplets with the reaction gas. Provision is made for renewing the braking foam placed over the liquid reactive bath and the reactive gas is supplied in the form of a blade-like stream so as to improve the contact time and intensity between the droplets and the reactive gas.

Abstract: A process for the production of microspheres of thorium oxide, uranium oxide or plutonium oxide and mixtures thereof, containing carbon. The microspheres are prepared by first forming an aqueous alkaline solution of a salt of said metals which will precipitate to a solid form in a concentrated alkaline medium together with an alkaline polymerizable organic monomer and carbon, thereafter dripping this solution into a concentrated alkaline medium wherein metal hydroxide is precipitated out and said monomers polymerized to thereby form said microspheres. The precipitated metal compounds with polymerized monomer and carbon are washed to remove unwanted ions and dried by various methods such as air currents, infrared lamps, high frequency microwaves or preferably by azeotropic distillation whereby the washed particles are dispersed in an organic liquid immiscible with water which is then boiled off. Simple liquids include 1,1,1-trichloroethane, carbontetrachloride and xylene.