Process and apparatus for producing fine particles

A process for producing fine particles, comprising the steps of:

• introducing a material for producing, the fine particles into a thermal plasma flame to make a vapor-phase mixture;
• and
• quenching the vapor-phase mixture to form the fine particles,
• wherein said step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:
• dissolving the material for producing the fine particles in a solvent to prepare a solution;
• and
• making the solution into a form of droplets so as to introduce the solution in a droplet form into the thermal plasma flame.

A process for producing fine particles, comprising the steps of:

• introducing primary fine particles formed by a predetermined treatment into at least one cyclone to subject the primary fine particles to cooling and classification based on a predetermined particle size;
• removing coarse particles having a particle size equal to or greater than the predetermined particle size by the classification;
• and
• recovering secondary fine particles having a particle size of 100 nm or less which are left upon removal of the coarse particles;
• wherein the treatment for forming the primary fine particles is a treatment in which a material for producing the fine particles is dispersed and then introduced into a thermal plasma flame so as to evaporate the material for producing the fine particles to make a vapor-phase mixture.

A fine particle producing apparatus, comprising:

• a material supplying section that disperses a material for producing fine particles and supplies the dispersed material into a thermal plasma flame;
• a plasma torch connected to said material supplying section that generates said thermal plasma flame so as to evaporate the material for producing the fine particles to make a vapor-phase mixture;
• a cooling chamber connected to said plasma torch that provides a space necessary to quench said vapor-phase mixture;
• and
• a gas supplying section that supplies a as of an amount sufficient to quench the vapor-phase mixture toward a tail of said thermal plasma flame.

A fine particle producing apparatus, comprising:

• a material supplying section that disperses a material for producing fine particles and supplies the dispersed material into a thermal plasma flame;
• a plasma torch connected to said material supplying section that generates said thermal plasma flame so as to evaporate the material for producing the fine particles to make a vapor-phase mixture;
• a cooling chamber connected to said plasma torch that provides a space necessary to quench the vapor-phase mixture;
• and
• at least one cyclone as a classifying section into which primary fine particles formed by quenching the vapor-phase mixture are introduced.