WO2001036898A2

WO2001036898A2 - Demilitarization of wax desensitized explosives

Info

Publication number: WO2001036898A2
Application number: PCT/US2000/040887
Authority: WO
Inventors: Michael J. Chanak; Bruce A. Bromberek
Original assignee: Gradient Technology
Priority date: 1999-09-14
Filing date: 2000-09-13
Publication date: 2001-05-25
Also published as: WO2001036898A3

Abstract

A method for demilitarizing munitions, typically military shells, containing an explosive composite material comprised of an explosive component and a wax component as a binder and desensitizing agent. The shells are opened to expose the explosive composite material, which is then removed from the shell by any suitable means. The wax component is then separated from the explosive component by dissolving the wax in a suitable solvent, then flashing off the solvent for recycle.

Description

DEMILITARIZATION OF WAX DESENSITIZED EXPLOSIVES

Field of the Invention

The present invention relates to a method for demilitarizing munitions, typically military shells, containing an explosive composite material comprised of an explosive component and a wax component as a binder and desensitizing agent. The shells are opened to expose the explosive composite material that is then removed from the shell by any suitable means. The wax component is then separated from the explosive component by dissolving the wax in a suitable solvent, then flashing off the solvent for recycle.

Background of the Invention

Surplus munitions present a unique problem to the US military. The US military must prioritize its spending to effectively defend the interests of the United States in this current period of tight budget constraints. Maintaining aging and surplus munitions tightens defense budgets because it requires expenditures for security and storage facilities. Further, the US military must regularly destroy a significant amount of munitions that are surplus, that have deteriorated, and that are obsolete.

In the past, munitions stocks have been disposed of by such methods as dumping them in the ocean, or by open burn/open detonation (OB/OD) methods. Although such methods effectively destroy munitions, they fail to meet the challenge of minimizing waste by-products in a cost-effective manner. Further, such methods of disposal are undesirable from an environmental point of view because they contribute to contamination of the oceans and/or to the pollution of the atmosphere. For example, OB/OD methods, the most inexpensive and technologically simple disposal methods available, produce relatively high levels of NO_x, acidic gases, particulates, and metal waste. Furthermore, incomplete combustion products can leach into the soil and contaminate ground water from pits used for open burn methods. Often the surrounding soil and ground water must be remediated to meet environmental guidelines after OB/OD methods have been used. Conventional incineration methods can also be used to destroy munitions, but they require a relatively large amount of fuel. They also produce relatively large amounts of gaseous effluent that must be treated to remove undesirable components before it can be released into the atmosphere. Thus, OB/OD and incineration methods of disposing of munitions become impractical owing to increasingly stringent federal and state environmental protection regulations. Further, today's ever-stricter environmental regulations require that new munitions and weapon system designs address demilitarization processing issues.

Munitions containing wax as a desensitizing agent are presently in need of demilitarization. One of the most common formulations, Composition A-3, is prepared by adding melted wax, usually beeswax, and a surfactant to explosive crystals in hot water. The solution is mixed and passed through rollers and dried to form wax- coated particles. The resulting composite particles were typically comprised of about 91 wt.% explosive and about 9 wt.% wax. The particles are then press loaded into munition casings (shells). The wax coating protects the explosive crystals from the intense point stresses and friction experienced during manufacturing and handling, thus preventing premature detonation. A conventional method for demilitarizing wax- desensitized munitions was to use hot water to melt the wax with the expectation that the explosive crystals would settle out. Unfortunately, the degree of recovery of explosive fell substantially short of expectations. In addition, such technology cannot be used with aluminum containing munitions, nor can it be applied to munitions made with high melting point waxes (m.p. > 100°C).

Thus, there is a need in the demilitarization art for processes that will meet the goals of resource reuse and recovery of the explosive component at commercially acceptable yields. The process of the present invention meets these goals with respect to the demilitarization of wax-desensitized munitions.

Summary of the Invention

In accordance with the present invention, there is provided a process for demilitarizing a munition containing a wax desensitized explosive material comprised of a wax component and an explosive component, which process comprises: a) exposing the wax desensitized explosive material in the munition; b) removing the wax desensitized explosive material from the munition; c) dissolving at least a fraction of the wax with a solvent in which the wax is at least partially soluble at about room temperature, thereby resulting in a wax/solvent component and an explosive component; d) separating the wax/solvent component from the explosive component; e) collecting the explosive component; f) separating the wax component from the solvent; g) collecting the wax component; h) recovering the solvent.

In a preferred embodiment, the wax is a naturally occurring wax, preferably beeswax.

In another preferred embodiment the solvent is an alkane solvent.

In still another preferred embodiment the solvent is a normally liquid solvent.

In another preferred embodiment the explosive is selected from the group consisting of RDX and HMX.

In yet another preferred embodiment the munition is a military shell and the wax desensitized explosive material is removed from the shell by use of a high- pressure fluid jet.

In still another preferred embodiment of the present invention the pressure of the fluid jet is from about 20,000 psi to about 150,000.

In another preferred embodiment the fluid of the fluid jet is a solvent in which the wax is at least partially soluble. Detailed Description of the Invention

Munitions that are the subject of this invention are wax-desensitized munitions. That is, munitions that contain a major amount of explosive component and a minor amount of wax to desensitize the explosive component. The wax bonds and coats the explosive component, thereby protecting it from the intense point stresses and friction experienced during manufacturing and handling. This prevents premature detonation The wax can be any naturally occurring or synthetic wax that is suitable for use in munitions. Waxes are typically referred to as "synthetic" if they are fractionally distilled from petroleum and specific portions reblended. Natural waxes are waxes derived from animal, insect, mineral/petroleum, and vegetable sources. Non-limiting examples of waxes that are suitable for being recovered in the process of the present invention include: a) insect and animal waxes, preferably beeswax, Chinese insect wax, wool wax, and spermaceti; b) vegetable waxes, such as candelilla, carnauba, Japan wax, ouricury wax, rice-bran wax, jocoba, castor wax, and bayberry wax; c) mineral waxes, such as montan wax, peat wax, ozokerite and ceresin waxes; d) petroleum waxes, such as paraffin and microcrystalline waxes; and e) synthetic waxes, such as polyethylene waxes, and mixtures thereof.

The most preferred wax is beeswax since there is a substantial stockpile of munitions that contain beeswax as a desensitizing agent.

In order to demilitarize munitions containing wax desensitized explosives, under modern demilitarization requirements, all components of the munitions need to be recovered is a commercially useful form that is not harmful to the environment. Prior art attempts to recover the wax component from the explosive component involved the use of hot water to melt the wax with the expectation that the explosive component would merely settle out. Surfactants were added to improve the separation of the explosive from the water/wax phase, but the degree of separation was far less than desirable and commercially feasible. The present invention is capable of overcoming these shortcomings.

Non-limiting examples of explosives that can be used in wax- desensitized munitions of the present invention include: cyclotrimethylenetrinitramine (RDX); cyclotetromethylene tetranitramine (HMX); 2-methyl-l,3,5-trinitrobenzene (TNT); Amatol (Ammonium Nitrate/TNT); Cyclotol (RDX TNT); Octol (HMX TNT); and any of the preceding combined with aluminum particles (Al). Preferred are RDX, TNT, and HMX.

Non-limiting examples of standard military explosives containing waxes are: Composition B and B-5 (RDX/TNT); Torpex 2 and Torpex D-l (RDX TNT/A1); HBX, HBX-1, and IINX-3 (RDX TNT/Al); H-6 (RDX TNT/AI); Composition A-3, A- 5, A-6, A-7 (RDX).

Solvents suitable for use herein are those solvents in which the wax is at least partially soluble. Preferred are those solvents that will dissolve substantially all of the wax. More preferred solvents are those that will dissolve substantially all of the wax while having substantially no solvent properties with respect to the explosive component. Non-limiting examples of solvents that can be used in the practice of the present invention include Ci to Cio alkanes, especially the C₅ to C₈ alkanes, more preferably hexane or heptane. Also suitable are ethylene, propylene, butylene, sulfur dioxide, CHF₃, CC1F₃, CFBr₃, CF₂=CH₂, CF₃-CF₂-CF₃, CF₄, CF₄, CH₃-CF₃, CHC1₂, nitrogen, dichlorodifluor methane, carbon dioxide, dimethylether, methyl fluoride, and halogenated hydrocarbons, and mixtures thereof. Preferred are the alkanes, more preferably the C₅ to C₈ alkanes, and most preferably hexane or heptane. It is more preferred that the solvents be used in a liquid state, although it is within the scope of this invention that solvents in the gaseous state be used. Also, conditions at which the solvent is used to extract the wax can be either supercritical or subcritical conditions.

In one preferred embodiment the present invention will be practiced by exposing the wax desensitized explosive material in the munition, preferably a military shell, for removal. Any suitable technique can be used to expose the explosive material. For example, the explosive material can be exposed by cutting open the shell using any appropriate cutting method known in the art. One preferred cutting method is the use of a fluid jet. It is preferred that the shell be cut across its longitudinal axis at a point that would expose substantially all of the wax desensitized explosive for removal. That is, an end of the shell. The wax desensitized explosive material can also be exposed by removing the fuse, or fill plug, of the shell, thereby exposing the wax desensitized material. Any suitable technique can be used to remove the wax desensitized explosive material from the shell. For example, the shell can be heated to a high enough temperature that will soften the wax but below a temperature that will induce detonation of the explosive component. Typical temperatures will be from about 60°C to about 220°C, preferably from about 80°C to about 180°C.

The wax can be dissolved in the solvent at any suitable temperature, preferably from about 5°C to about 220°C, more preferably from about 60°C to 220°C, and most preferably from about 80°C to about 180°C.

The wax desensitized explosive material can also be removed from the shell by use of fluid jet washout technology at pressures that are effective to erode, or comminute, the wax desensitized explosive material. The preferred type of fluid jet washout equipment which can be used in the practice of the present invention is described in US Patent No. 5,737,709 which is incorporated herein by reference. It is preferred that the fluid jet washout step of the present invention be able to achieve a 5X cleanliness that is required by Army Material Command Regulation 385-5 for explosives and Army Material Command Regulation 385-61 for chemical weapons.

The operating pressure of the fluid jets will be from about 20,000 to 150,000 psi, preferably from about 40,000 to 150,000 psi. The preferred range of pressures can be used provided that the diameter of the washout stream is in the range of about 0.001" to about 0.02".

It is within the scope of the present invention that the washout fluid be chilled to a temperature below the melting point of the wax component of the wax desensitized explosive material. If chilled, it is preferred that it be at a temperature from about 5 to 15°C, more preferably to a temperature from about 10 to 15°C. If the fluid used for the fluid jet is water, the washed out wax desensitized explosive material, which is now in particulate form, is dried by conventional drying techniques prior to being exposed to the solvent. One preferred embodiment is to combine the steps of removal of the wax desensitized explosive material and solubihzing the wax. For example, a fluid jet can be used to remove the material from the shell, and the fluid can be a solvent with respect to the wax.

The following examples are presented for illustrative purposes and are not to be considered limiting the present invention in any way.

Examples

Experiments were performed with surrogate wax desensitized material.

Surrogate Composition A3 material was manufactured by melting a measured amount of beeswax with nine times the amount (by weight) of glass beads. The glass beads, similar in size and shape to RDX crystals, were added to the melted wax to form a paste, which paste was placed in a shell casing. The wax/glass bead mixture was allowed to cool and harden. This resulted in a solid mass of glass beads encased in wax.

To recover the glass beads from the wax/glass bead composite material, the composite material is removed from the shell casings and fed as large solid particles into a vessel. Hexane is then introduced into the vessel and the composite solid particles treated with hexane solvent at a temperature of about 70°F for about 3 minutes. The solvent quickly dissolved the wax and the glass beads settled out of solution. The glass beads were then removed and washed with additional hexane. The solvent was then flashed off and the glass particles recovered. The wax containing solvent was flashed to recover the wax.

In the case of actual explosive material an additional processing step is required. A passivating solution such as water or alcohol is added to the recovered explosive crystals to decrease sensitivity, thus decreasing the risk of explosion.

Claims

What is claimed is:

1. A process for demilitarizing a munition containing a wax desensitized explosive material comprised of a wax component and an explosive component, which process comprises:

a) exposing the wax desensitized explosive material in the munition;

b) removing the wax desensitized explosive material from the munition;

c) dissolving at least a fraction of the wax with a solvent in which the wax is at least partially soluble at about room temperature, thereby resulting in a wax/solvent component and an explosive component;

d) separating the wax/solvent component from the explosive component;

e) collecting the explosive component;

f) separating the wax component from the solvent;

g) collecting the wax component; and

h) collecting the solvent for recycle.

2. The process of claim 1 wherein the wax is a naturally occurring wax.

3. The process Of claim 2 wherein the wax is a beeswax.

4. The process of claim 1 wherein the wax is a synthetic wax.

5. The process of claim 1 wherein the solvent is selected from the group consisting of C] to Cio alkanes, ethylene, propylene, butylene, sulfur dioxide, CHF₃, CC1F₃, CFBr₃, CF =CH₂, CF₃-CF₂-CF₃, CF₄, CF₄, CH₃-CF₃, CHC1₂, nitrogen, dichlorodifluor methane, carbon dioxide, dimethylether, methyl fluoride, and halogenated hydrocarbons, and mixtures thereof.

6. The process of claim 5 wherein the solvent is a C₅ to Go alkane.

7. The process of claim 6 wherein the solvent is hexane or heptane.

8. The process of claim 1 wherein the temperature at which the wax is dissolved in the solvent is from about 60°C to about 220°C.

9. The process of claim 8 wherein the temperature at which the wax is dissolved in the solvent is from about 80°C to about 180°C.

10. The process of claim 1 wherein the explosive component is selected from the group consisting of cyclotrimethylenetrinitramine (RDX); cyclotetromethylene tetranitramine (HMX); 2-methyl-l,3,5-trinitrobenzene (TNT); Amatol (Ammonium Nitrate TNT); Cyclotol (RDX TNT); and Octol (HMX TNT).

1 1. The process of claim 10 wherein there is also present aluminum particles.

12. The process of claim 1 1 wherein the explosive is selected from the group consisting of RDX, TNT, and HMX.

13. The process of claim 1 wherein the wax desensitized material is removed from the munition by use of a high-pressure fluid jet.

14. The process of claim 13 wherein the fluid is water.

15. The process of claim 13 wherein the fluid is solvent with respect to the wax component.

16. The process of claim 1 wherein the munition is a military shell.

17. A process for demilitarizing a military shell containing a wax desensitized explosive material comprised of a wax component and an explosive component, which process comprises: a) exposing the wax desensitized explosive material in the shell by cutting the shell open across its longitudinal axis; b) removing the wax desensitized explosive material from the shell; c) dissolving at least a fraction of the wax with an alkane solvent in which the wax is at least partially soluble at about room temperature, thereby resulting in a wax/solvent component and an explosive component; d) separating the wax/solvent component from the explosive component; e) collecting the explosive component; f) separating the wax component from the solvent; g) collecting the wax component; h) collecting the solvent for recycle.

18. The process of claim 17 wherein the solvent is selected from the C| to Cio alkanes.

19. The process of claim 17 wherein the solvent is hexane.

20. The process of claim 17 wherein the wax is a naturally occurring wax.

21. The process of claim 20 wherein the wax is a beeswax.

22. The process of claim 20 wherein the temperature at which the wax is dissolved in the solvent is from about 80°C to about 180°C.

23. The process of claim 22 wherein the explosive component is selected from the group consisting of cyclotrimethylenetrinitramine (RDX); cyciotetromethylene tetranitramine (HMX); 2-methyl-l,3,5-trinitrobenzene (TNT); Amatol (Ammonium Nitrate/TNT); Cyclotol (RDX/TNT); and Octol (HMX TNT).

24. The process of claim 23 wherein there is also present aluminum particles.

25. The process of claim 23 wherein the explosive is selected from the group consisting ofRDX, TNT, and HMX.

26. The process of claim 23 wherein the fluid is water.

27. The process of claim 23 wherein the fluid is solvent with respect to the wax component.