Process for the production of an exothermically reacting composition

• US 6,416,600 B1
• Filed: 08/17/1995
• Issued: 07/09/2002
• Est. Priority Date: 08/17/1994
• Status: Expired due to Fees

• Current Assignee: Imperial Chemical Industries PLC (IMPERIAL CHEMICAL INDUSTRIES)
• Original Assignee: Imperial Chemical Industries PLC (IMPERIAL CHEMICAL INDUSTRIES)
• Inventors: Graham, Derek Alexander, Clarke, Kay Heather, Oliver, Ray
• Primary Examiner(s): Miller, Edward A.
• Application Number:
  US08/516,259
• Time in Patent Office: 2,518 Days
• Field of Search: 149/19.92, 149/109.6, 264/3.4
• US Class Current: 149/109.6
• CPC Class Codes: C06B 21/0091 Elimination of undesirable or temporary components of an intermediate or finished product, e.g. making porous or low density products, purifying, stabilising, drying; Deactivating; Reclaiming; porous inert particles or chemicals compounded for these purposes C06B23/00
• CPC Class Codes: F26B 5/065 the product to be freeze-dried being sprayed, dispersed or pulverised

Abstract

A process for the production of an exothermically reacting composition, such as a propellant or explosive, containing at least one normally solid reactive constituent comprises the steps of:

forming a uniform dispersion of the ingredients of the said composition in a carrier liquid;

forming droplets of said dispersion;

feeding said droplets into a cooling medium at a temperature below the freezing point of said carrier liquid to form solidified droplets; and

freeze-drying said solidifed droplets.

Claims

1. A process for the production of particles comprising an exothermically reacting composition containing at least one normally solid reactive constituent comprising:

forming a uniform dispersion of ingredients of said composition in a carrier liquid;

forming droplets of said dispersion;

spraying said droplets into a gaseous medium at a temperature below the freezing point of said carrier liquid to form solidified droplets in said gaseous medium; and

freeze-drying said solidified droplets.

2. A process as claimed in claim 1 wherein the exothermically reactive composition comprises at least one reactive ingredient which is soluble in the carrier liquid and is at least partially dissolved in the carrier liquid.

3. A process as claimed in claim 1 wherein the said reactive constituent is water-soluble and the said carrier liquid comprises water.

4. A process as claimed in claim 1 wherein the dispersion is formed into droplets having diameter in the range from 50-500 microns.

5. A process as claimed in claim 1 wherein the temperature of the cooling medium is in the range −

40 to −

195°

C.

6. A process as claimed in claim 1 wherein the said solidified droplets are freeze-dried by heating in a vacuum chamber at a pressure below the triple point of the solvent, and condensing the sublimed solvent vapour on a cold surface.

7. A process as claimed in claim 4 wherein the droplets have a diameter in the range of 75 to 200 microns.

8. A process as claimed in claim 6 wherein the pressure is below 6.11 mbar.

9. A process as claimed in claim 8 wherein the pressure is maintained at 0.1 to 2.0 mbar.

10. A process as claimed in claim 6 wherein the solvent is water.

11. A process as claimed in claim 1 wherein the gaseous cooling medium is selected from the group consisting of air, nitrogen, carbon dioxide, argon and helium.

12. The process as claimed in claim 1 wherein the gaseous medium is recycled through a refrigeration means.

13. The process as claimed in claim 1 wherein the gaseous medium is cooled by a recycled refrigerated fluid.

14. The process as claimed in claim 1 wherein the particles have a pore size of from 0.2 to 10 microns.

15. The process as claimed in claim 1 wherein the particles have a pore size of from 0.2 to 1 micron.

16. The process as claimed in claim 1 wherein the particles have a porosity of from 10% to 80% by volume.

17. The process as claimed in claim 1 wherein the particles have a porosity of from 40% to 70% by volume.

18. The process as claimed in claim 1 wherein the reactive constituent is a mixture which includes sodium azide and iron oxide;

ammonium nitrate and a fuel;

ammonium nitrate and carbon black;

potassium nitrate, carbon and sulfur;

potassium nitrate and sodium poly(styrene sulfonate);

potassium permanganate and antimony;

ferric oxide and boron; and

/or potassium nitrate and boron.