GB1317388A - Method of manufacturing spherical particles - Google Patents

Abstract

1317388 Making spherical particles BELGONUCLEAIRE SA 19 Oct 1971 [20 Oct 1970 (2)] 48584/71 Heading B5A [Also in Division C1] Spherical particles, especially nuclear fuel particles, are made by projecting a stream of gas which carries liquid droplets on to the surface of a bath at an acute angle thereto, the bath containing a liquid which will cause the droplets to solidify, or to form pellicles. Preferably the bath 7 has a thin surface covering 10 of a further liquid which is inert and has a desnity only slightly lower than that of the main liquid 11; the gas stream issuing from a nozzle 4 produces a wave 8 on the surface of this inert layer and the droplets roll down it to acquire spherical form before entering the liquid of the bath which preferably contains a reagent which will result in the formation of a solid precipitate. For nuclear fuel the droplets are formed from a solution or dispersion of salts of uranium, plutonium, thorium or other transuranian elements. In an example a solution of uranylnitrate is prepared from butylglycol and methylcellulose and an aqueous solution of this with nitric acid is fed through an injector 2 fitted with a stop-valve 3, a gas stream, e.g. of air, nitrogen or argon, being supplied through the outer tube 4 and the angle to the horizontal 6 being less than 45 degrees and preferably between 25 and 35 degrees. The bath contains a layer 10 of amyl alcohol floating on liquid ammonia 11 in a cylindrical bath and the droplets are projected tangentially to the peripheral rim. The droplets form into pellicles as they fall through the liquid ammonia and the reaction then continues until they are transformed into ammonium-diuranate particles which are filtered, dried and sintered in a reducing atmosphere to uranium dioxide. Suitable quantities and dimensions are given for the components. The inert liquid may be other organic alcohols or compounds such as benzene, xylene or heptane.