Process and apparatus for producing spherical particles and fibers with a specially fixed size from melts

A process for producing spherical particles with an analytically predetermined diameter from a melt comprising:

• establishing a kinematic viscosity of the melt in a range of 0.001 to 10 cm.sup.2 /sec.;
• wherein said melt comprises essentially at least one material selected from the group comprising metal, slag, flux and the mixture thereof;
• introducing the melt through a conduit having an outlet which provides a predetermined outflow velocity in a range of 5 to 500 cm/sec onto a rotating disk having a flat refractory surface, said disk having an effective diameter in the range of 50 to 200 mm and a rotational speed of 3,000 to 30,000 rpm;
• setting said conduit having a radius r.sub.o of 3 to 30 mm so that the distance h.sub.o between said conduit outlet and said disk surface is maintained within a range of (r.sub.o /2) to (r.sub.o /2+2 mm), wherein r.sub.o is the radius of said conduit;
• said melt forming a thin film stream with a predetermined thickness, at least, in the proximity of the periphery of said disk surface by centrifugal force, said thin film being provided with a tangential velocity component as well as a radial velocity component throughout the entire thickness thereof, said thickness being controlled by said effective diameter of said disk surface in the aforesaid range of 50 to 200 mm and said rotational speed of said disk in a range of 3,000 to 30,000 rpm and said kinematic viscosity of the melt;
• whereby said thin film stream is projected into free space from the periphery of said disk by said centrifugal force and split into free linear streams with a predetermined radius by a sudden removal of said tangential velocity component and from additional action resulting from surface tension;
• forcing a gas having a lower temperature and a higher pressure than atmospheric values against said linear streams, said gas streams being parallel and counter in direction to said linear streams of the melt, thereby shortening the time and path of the space motion of said linear streams;
• said free linear streams rapidly splitting into spherical droplets with a predetermined diameter by rapidly decelerating the velocity of said streams to a fixed value from the effects of surface tension acting on said streams;
• and
• solidifying said spherical droplets whereby spherical particles with an analytical predetermined diameter are produced.