Process and Apparatus for Producing Fine Particles

• US 20080006954A1
• Filed: 09/07/2005
• Published: 01/10/2008
• Est. Priority Date: 09/07/2004
• Status: Active Grant

• Current Assignee: Nisshin Engineering, Inc. (Nisshin Seifun Group Incorporated), Nisshin Seifun Group Incorporated
• Original Assignee: Nisshin Engineering, Inc. (Nisshin Seifun Group Incorporated), Nisshin Seifun Group Incorporated
• Inventors: Fujii, Takashi, Nakamura, Keitaroh, Yubuta, Kazuhiro
• Granted Patent: US 7,828,999 B2
• Time in Patent Office: Days
• US Class Current: 264/005
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 2219/0869 Feeding or evacuating the reactor
• CPC Class Codes: B01J 2219/0871 Heating or cooling of the reactor
• CPC Class Codes: B01J 2219/0877 Liquid
• CPC Class Codes: B01J 2219/0884 Gas-liquid
• CPC Class Codes: B01J 2219/0898 Hot plasma
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 13/34 by oxidation or hydrolysis of sprayed or atomised solutions
• CPC Class Codes: C01F 7/027 Treatment involving fusion or vaporisation
• CPC Class Codes: C01F 7/30 Preparation of aluminium oxide or hydroxide by thermal decomposition or by hydrolysis or oxidation of aluminium compounds
• CPC Class Codes: C01F 7/308 Thermal decomposition of nitrates
• CPC Class Codes: C01G 1/00 Methods of preparing compounds of metals not covered by subclasses C01B, C01C, C01D, or C01F, in general electrolytic production of inorganic compounds C25B1/00
• CPC Class Codes: C01G 1/02 Oxides
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C09C 1/407 Aluminium oxides or hydroxides

Abstract

A fine particle producing process introduces a material for producing fine particles into a thermal plasma flame to make a vapor-phase mixture and quenches the vapor-phase mixture to form the fine particles. In the process, the material for producing the fine particles is dispersed or dissolved in a dispersion medium or solvent, preferably containing a combustible material to prepare a dispersion such as a slurry, a colloidal solution or a dissolution solution, the dispersion is made into a form of droplets, or the material for producing the fine particles is dispersed with a carrier gas and a combustible material and the dispersion in a droplet form or the dispersed material is introduced into the thermal plasma flame. In the fine particle producing process and apparatus, a gas of an amount sufficient to quench the vapor-phase mixture is supplied toward a tail of the thermal plasma flame. In the process and apparatus, primary fine particles are introduced into a cyclone to be subjected to cooling and classification and secondary fine particles having a particle size of 100 nm or less which are left upon removal of coarse particles are recovered.

Claims

1. 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;

dispersing or dissolving the material for producing the fine particles in a dispersion medium or solvent containing a combustible material to prepare a dispersion; and

making the dispersion into a form of droplets so as to introduce the dispersion in a droplet form into the thermal plasma flame, or dispersing the material for producing the fine particles with a carrier gas and a combustible material and introducing the dispersed material for producing the fine particles into the thermal plasma flame.

8. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles in a combustible material to prepare a slurry;

making the slurry into the form of droplets; and

introducing the slurry in the droplet form into the thermal plasma flame.

9. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles using a dispersion medium and a combustible material to prepare a slurry;

making the slurry into the form of droplets; and

introducing the slurry in the droplet form into the thermal plasma flame.

10. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles in a dispersion medium, and then adding thereto a combustible material to prepare a slurry;

making the slurry into the form of droplets; and

introducing the slurry in the droplet form into the thermal plasma flame.

12. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

suspending the material for producing the fine particles in a combustible material to prepare a colloidal solution;

making the colloidal solution into the form of droplets; and

introducing the colloidal solution in the droplet form into the thermal plasma flame.

13. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

suspending the material for producing the fine particles in a dispersion medium and a combustible material to prepare a colloidal solution;

making the colloidal solution into the form of droplets; and

introducing the colloidal solution in the droplet form into the thermal plasma flame.

14. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

suspending the material for producing the fine particles in a dispersion medium, and then adding a combustible material to prepare a colloidal solution;

making the colloidal solution into the form of droplets; and

introducing the colloidal solution in the droplet form into the thermal plasma flame.

16. The process for producing fine particles according to claim 1, wherein the 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 using a combustible material to prepare a dissolution solution;

making the dissolution solution into the form of droplets; and

introducing the dissolution solution in the droplet form into the thermal plasma flame.

17. The process for producing fine particles according to claim 1, wherein the 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 using a solvent and a combustible material to prepare a dissolution solution;

making the dissolution solution into the form of droplets; and

introducing the dissolution solution in the droplet form into the thermal plasma flame.

18. The process for producing fine particles according to claim 1, wherein the 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, and then adding a combustible material to prepare a dissolution solution;

making the dissolution solution into the form of droplets; and

introducing the dissolution solution in the droplet form into the thermal plasma flame.

20. The process for producing fine particles according to claim 1, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles using a carrier gas and a combustible material; and

introducing the dispersed material for producing the fine particles into the thermal plasma flame.

21. The process for producing fine particles according to claim 1, wherein the combustible material has action of stabilizing the thermal plasma flame. Note that various liquid and solid materials can be used as the combustible material.

26. The process for producing fine particles according to claim 1, wherein components that constitute the material for producing the fine particles are simple oxides, composite oxides, double oxides, oxide solid solutions, metals, alloys, hydroxides, carbonate compounds, halides, sulfides, nitrides, carbides, hydrides, metal salts or organometallic compounds that contain at least one element selected from the group consisting of the elements having atomic numbers of 3 to 6, 11 to 15, 19 to 34, 37 to 52, 55 to 60, 62 to 79, and 81 to 83.

2. 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.

11. The process for producing fine particles according to claim 2, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

suspending the material for producing the fine particles in a dispersion medium to prepare a colloidal solution;

making the colloidal solution into the form of droplets; and

introducing the colloidal solution in the droplet form into the thermal plasma flame.

15. The process for producing fine particles according to claim 2, wherein the 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 dissolution solution;

making the dissolution solution into the form of droplets; and

introducing the dissolution solution in the droplet form into the thermal plasma flame.

23. The process for producing fine particles according to claim 11, wherein one or more substances selected from the group consisting of a surfactant, a high polymer, and a coupling agent are added singly or in admixture to the colloidal solution.

24. The process for producing fine particles according to claim 15, wherein one or more substances selected from the group consisting of a surfactant, a high polymer, and a coupling agent are added singly or in admixture to the dissolution solution.

3. 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

supplying a gas of an amount sufficient to quench the vapor-phase mixture toward a tail of the thermal plasma flame to form the fine particles.

7. The process for producing fine particles according to claim 3, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles in a dispersion medium to prepare a slurry;

making the slurry into the form of droplets; and

introducing the slurry in the droplet form into the thermal plasma flame.

19. The process for producing fine particles according to claim 3, wherein the step of introducing the material for producing the fine particles into the thermal plasma flame comprises the steps of:

dispersing the material for producing the fine particles using a carrier gas; and

introducing the dispersed material for producing the fine particles into the thermal plasma flame.

22. The process for producing fine particles according to claim 7, wherein one or more substances selected from the group consisting of a surfactant, a high polymer, and a coupling agent are added singly or in admixture to the slurry.

25. The process for producing fine particles according to claim 19, wherein one or more substances selected from the group consisting of a surfactant, a high polymer, and a coupling agent are added singly or in admixture to the dispersed material for producing the fine particles.

4. 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.

5. The process for producing fine particles according to claim 4, 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.

6. The process for producing fine particles according to claim 5, wherein, in the treatment for forming the primary fine particles, after the material for producing the fine particles is evaporated to make the vapor-phase mixture, a gas for quenching the vapor-phase mixture is supplied toward a tail of the thermal plasma flame in an amount of from 200% to 5,000% of an amount of the gas introduced into the thermal plasma flame.

27. 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 gas of an amount sufficient to quench the vapor-phase mixture toward a tail of said thermal plasma flame.

30. The fine particle producing apparatus according to claim 27, wherein said material supplying section comprises:

a material preparing section that disperses the material for producing the fine particles to prepare a slurry and stores the slurry thus prepared; and

a spray section that is connected to said material preparing section, and that sprays the slurry into said thermal plasma flame inside said plasma torch.

31. The fine particle producing apparatus according to claim 27, wherein said material supplying section comprises:

a material preparing section that suspends the material for producing the fine particles or subjects a solution of material for producing the fine particles to a chemical reaction to prepare a colloidal solution and stores the colloidal solution thus prepared; and

a spray section that is connected to said material preparing section, and that sprays the colloidal solution into said thermal plasma flame inside said plasma torch.

32. The fine particle producing apparatus according to claim 27, wherein said material supplying section comprises:

a material preparing section that dissolves the material for producing the fine particles to prepare a dissolution solution and stores the dissolution solution thus prepared; and

a spray section connected to said material preparing section that sprays the dissolution solution into said thermal plasma flame inside said plasma torch.

33. The fine particle producing apparatus according to claim 27, wherein said material supplying section comprises:

a powder material supplying section that delivers a powder material as the material for producing the fine particles from a section for its storage; and

a section for transportation by gas connected to the powder material supplying section that disperses the powder material with a carrier gas and supplies the dispersed material into said thermal plasma flame inside said plasma torch.

28. 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.

29. The fine particle producing apparatus according to claim 28, further comprising:

a gas supplying section that supplies a gas of an amount sufficient to quench the vapor-phase mixture toward a tail of said thermal plasma flame.