Method for making spherical particles

A process for making spheres from a multiplicity of minute particles, the process comprising, in combination:

• introducing a multiplicity of the particles into a fluidizing bed;
• directing an inert fluidizing gas into the bed to suspend the particles in an inert atmosphere and thereby fluidize the same;
• applying heat to the fluidizing gas to raise the temperature of the particles sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said bed;
• and
• thereafter cooling the spherical particles while maintaining the particles in a fluidized condition for a period of time sufficient to cause the setting of the spheres.

A process for making spheres from a multiplicity of minute particles, the process comprising, in combination:

• introducing a multiplicity of the particles into a first fluidizing bed;
• directing a fluidizing material into the first bed to suspend the particles therein and thereby fluidize the same, the fluidized particles moving substantially randomly within said bed but without appreciable vertical movement of the mass of particles;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said first bed;
• and
• thereafter transferring said particles to a second fluidizing bed, the second bed maintaining the particles in a fluidized condition for a period of time sufficient to cause the setting of the spheres.

A process for making spheres from a multiplicity of minute particles, the process comprising, in combination:

• applying a protective coating to the particles;
• introducing the particles into a fluidizing bed;
• directing a fluidizing gas into the bed to suspend the particles therein and thereby fluidize the same;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said bed;
• cooling the spherical particles while maintaining the particles in a fluidized condition for a period of time sufficient to cause the setting of the spheres;
• and
• removing said coating from the spherical parti- cles.

A process for making spheres from a multiplicity of minute particles, the process comprising, in combin- ation:

• coating the particles with an oxidizable protective material;
• introducing the thus coated particles into a sphere forming enclosure;
• heating the particles to an elevated temperature sufficiently high to shape the particles into spherical form;
• thereafter cooling the particles for a period of time sufficient to cause the setting thereof to form spheres;
• and
• exposing the spheres to an oxidizing atmosphere to oxidize and remove said coating.

A process for making spheres from a multiplicity of minute particles, the process comprising, in combina- tion:

• coating the particles with an oxidizable adherent protective material, the amount of coating material applied to the particles lying within the range of from about 0.1% to about 0.5% by weight;
• introducing the thus coated particles into a sphere forming enclosure having an inert atmosphere;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form;
• thereafter cooling said particles for a period of time sufficient to cause the setting thereof to form spheres;
• and
• completely removing said coating from the spherical particles by oxidizing said coating.

A process for making glass spheres from minute glass particles, the process comprising, in combination:

• coating the glass particles with an oxidizable adherent protective material;
• introducing the thus coated particles into a sphere forming enclosure having an inert atmosphere;
• heating the particles to an elevated temperature sufficiently high to shape the particles into spherical form while in said enclosure;
• thereafter cooling said particles for a time sufficient to cause the setting of the spheres;
• and
• exposing the spheres to an oxidizing atmosphere to oxidize and remove said coating.

A process for making spheres from a multiplicity of minute particles, the process comprising, in combination:

• coating the particles with an oxidizable protective material;
• introducing the thus coated particles into a first fluidizing bed;
• directing an inert gas into the first fluidizing bed to suspend the particles in an inert atmosphere and thereby fluidize the same;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said first bed;
• transferring said particles to a second fluidizing bed, the second bed maintaining to continue to maintain the particles in a fluidized condition for a period of time sufficient to cause the setting of the spheres;
• and
• removing said coating from the spherical parti- cles.

A process for making glass spheres from minute glass particles, the process comprising, in combin- ation:

• coating the glass particles with an oxidizable adherent protective material;
• introducing the thus coated particles into a first fluidizing bed having an inert atmosphere;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said first bed;
• cooling said particles while maintaining the particles in a fluidized condition for a time sufficient to cause the setting of the spheres;
• and
• transferring the particles to a second fluidizing bed having an oxidizing atmosphere, the particles being maintained in a fluidized condition in said second bed for a period of time sufficient to oxidize and completely remove the protective coating thereon.

A process for making glass spheres from minute glass particles, the process comprising, in combin- ation:

• coating the glass particles with an oxidizable adherent protective material;
• introducing the thus coated particles into a first fluidizing bed having an inert atmosphere;
• heating the particles to an elevated temperature sufficiently high to allow surface tension to shape the particles into spherical form while in a fluidized condition in said first bed;
• cooling said particles while maintaining the particles in a fluidized condition for a time sufficient to cause the setting of the spheres;
• transferring the fluidized particles to a second fluidizing bed having an oxidizing atmosphere, the particles being maintained in a fluidized condition in said second bed for a period of time sufficient to oxidize and remove the protective coating thereon;
• and
• thereafter transferring said particles to a third fluidizing bed to further cool the particles.