US Government As Represented by the Secretary of the Army

William S Melvin

Robert E Betts

Lawrence B Thorn

Porter H Mitchell, Jr

James F Graham

Porter H Mitchell

A method to extract and recover nitramine oxidizers from solid propellant ing liquid ammonia employs four basic steps which are: (1) propellant removal by cutting or eroding into small pieces, followed by, (2) solution of the oxidizers by liquefied gas solvent ammonia, (3) separation of the insoluble binder, metal fuel, and additive components by filtration and recovery of the solid oxidizer by evaporation of the liquefied gas solvent ammonia, and (4) recompression to liquefy the gas solvent for reuse. The process is a closed system with no release of solvent to the environment. Cycle 1 reduces propellant size to 1/4 inch or less to achieve efficient extraction in cycle 2 where insoluble ingredients (binder, metal fuel, additives) are separated from soluble ingredients. Insolubles are recovered and the solubles are recovered in cycle 3 by evaporation of the liquefied gas solvent ammonia. Cycle 4 is a solvent liquefaction and recycling of the liquid ammonia to the closed system. Washing the extracted ingredients in ethanol separates insolubles, nitramine and impurities from solubles, degraded nitroglycerine and other plasticizers. Standard acetone/water or cyclohexanone/water solution is employed for recrystallization of nitramine (HMX and RDX) which are recovered in high purity.

Method to extract and recover nitramine oxidizers from solid propellants

A high impulse, non-detonable solid propellant grain is prepared from a cd detonable proepllant composition having a small critical diameter of less than one inch and an uncured detonable propellant composition having a large critical diameter of several inches. The method of preparation comprises grinding or cutting the cured detonable propellant composition into granules less than its critical diameter in any direction. An uncured propellant composition, in a predetermined amount of les than its critical diameter, is prepared, and the granules of the cured propellant are added and blended with the uncured propellant composition (which serves as the propellant binder) to form a homogeneous propellant blend. The homogeneous propellant blend is cured to yield a high impulse, non-detonable solid propellant grain having a critical diameter less than the critical diameter of the uncured propellant composition.

High impulse, non-detonable propellant

A method to extract and recover plasticizers and their stabilizers from solid propellants, explosives, and pyrotechnics (PEP source compositions) employs near critical liquid (NCL) or supercritical fluid (SCF) CO.sub.2 as the solvent. The extraction and ingredient recovery method provides an environmentally acceptable alternative to traditional open burning and destruction of PEP source compositions. CO.sub.2 solvent is nontoxic, nonflammable, noncorrosive, inexpensive, and does not generate any additional toxic or hazardous wastes. The solvent is totally inert when it is confined, pressurized, and possibly heated in direct contact with an energetic propellant or munition within a rocket motor or similar pressure vessel. CO.sub.2 readily undergoes a gas-to-liquid phase change to NCL conditions when confined and compressed to a pressure of 831 psig or greater at ambient temperature. By further increasing the pressure and temperature of NCL CO.sub.2 to 1058 psig and 31.3.degree. C. or greater, respectively, SCF conditions of CO.sub.2 are obtained. Either NCL or SCF CO.sub.2 has the capability to be a selective solvent for soluble plasticizers (e.g., nitroglycerin) and their stabilizers (e.g., diphenylamines and nitroanilines) from double base and crosslinked double base propellants, munitions and pyrotechnics. All undissolved propellant and munition ingredients are filtered from the NCL or SCF CO.sub.2 solvent prior to the pressure reduction/volume expansion recovery cycle. The recovery of soluble plasticizers and stabilizers from a NCL or SCF CO.sub.2 solvent system is achieved by allowing the NCL or SCF solvent to undergo pressure reduction and phase change to the gaseous state. The gaseous CO.sub.2 is then recycled for additional use in the method.

Extraction and recovery of plasticizers from solid propellants and

Liquid ammonia is maintained at the required operating conditions to efficiently and rapidly achieve propellant demilitarization including recovery of ammonia perchlorate (AP) for reuse, by an environmentally safe method to comminute and remove propellant from existing rocket motor hardware. The method is also applicable to both solid and ground composite propellant which includes scrap or waste propellant. A disclosed demilitarization unit employed in the ammonium perchlorate recovery method is comprised of a supply and high pressure spray system for liquid ammonia, an extraction system, oxidizer recovery system, and an ammonia recovery, drying, and recycling system. The method is workable at ambient temperature since ammonia is liquified under its own vapor pressure at 114 psig; however, increased temperature further enhances the extraction efficiency of the system. Solubilized ammonium perchlorate is separated after a phase change takes place through a liquid-gas expansion nozzle which provides a direct method to 'automatically precipitate and chemically grind' so to speak, the solid oxidizer AP particles to a predetermined, uniform size and configuration in accordance with established, solute purification techniques based on various temperature, pressure, and liquid nozzle spray conditions for particle size control when precipitated from a solvent. This method results in the rapid fall out of AP from liquid ammonia during the phase change or gasification stage since AP is insoluble in gaseous ammonia.

Method to dimilitarize extract, and recover ammonium perchlorate from

An effective method to recover the catalyst material, ferrocene or its deatives, from high burn rate propellants comprises the method which uses compressed gas in the form of a near critical liquid to extract, remove, and recover the specific catalyst material directly from rocket motors or from chunks of cut propellant. The method comprises introducing compressed carbon dioxide into a pressure vessel containing the propellant from which the catalyst material is to be recovered. The carbon dioxide as a near critical liquid (NCL) is circulated within the pressure vessel where extraction of ferrocene or its derivatives directly from the propellant takes place. The NCL with extractibles is transported to a warming and recovery zone where the extractibles are recovered after the carbon dioxide is volatilized and returned for recycling, compressing, and further extracting after being adjusted to a near critical liquid. Analytical data indicates that from 99.8% to 100% of ferrocence or its derivatives is readily recoverable from propellant which is undergoing demilitarization after it is determined to have burning rate, sensitivity, or other measureable changes to be out of system specification. After recovery of the high dollar value catalyst material, the propellant can be safely handled for removal using conventional water jet apparatus to cut and remove the propellant for reclamation of any of the propellant ingredients.

Demilitarization of high burn rate propellants containing ferrocene or

The mixing of high solids loaded propellants is accomplished under reduced viscosity conditions by employing near critical liquid (NCL) carbon dioxide as the processing fluid in a volume amount from about 10 to about 20 percent of the volume of the propellant ingredients. A typical propellant composition contains about 88 percent solids portion by weight comprised of ammonium perchlorate, aluminum powder, ballistic modifiers, and bonding agent and about 12 percent liquid portion by weight comprised of liquid polymers, plasticizers, and curatives. NCL carbon dioxide facilitates low viscosity mixing of propellant ingredients in a completely inert processing fluid. The method allows the entire mixing procedure to be conducted under reduced temperature conditions (e.g., 90.degree. F. vs 140.degree. F.), and thereby, provides for extended propellant pot life. Pressure mixing in a range of 760 psig to 1000 psig enables carbon dioxide to be maintained as a NCL to assist propellant mixing. When propellant mixing is completed, depressurization of the mixing chamber enables the NCL carbon dioxide to undergo a phase change to its gaseous state. Venting to ambient conditions, releases the gas from the propellant composition. Residual amounts of dissolved carbon dioxide can be completely removed under vacuum prior to propellant casting. If desired, the gaseous carbon dioxide can be contained and recycled for further use.

Processing of high solids propellant

A rocket motor that has a fast burning propellant therein with a dispenser rrangement for dispensing a fluid chemical suppressant into the exhaust gases of the solid propellant for reducing the flash signature.

Injectable fluid flash suppressor

A method and design are disclosed for the introduction of ammonia gas into he rocket motor gas environment wherein the ammonia gas functions to suppress the flash signature. The firing and pressurization of a sealed container having suppressant vents results in the rupturing of one or more seals for the container containing clathrate means from which adsorbed liquid or gaseus ammonia is boiled out and discharged and mixed with combustion gases prior to being discharged through the exhaust nozzle of a rocket motor. The design for the container for containing clathrate means include as part of one embodiment a toroidal shaped container for installing within the rocket motor exhaust nozzle wherein the container functions as the throat of the exhaust nozzle of the rocket motor. Other embodiments feature the clathrate means in a sealed container which additionally houses the ignitor means. The combination ignitor-clathrate means container is provided with a seal which ruptures when the ignitor means is fired, and the container is additionally provided with suppressant vents along the periphery and the end of the combination container through which the suppressant gas ammonia is boiled out of the clathrate means and subsequently discharged and mixed with rocket motor combustion gases prior to being exhausted through a rocket motor exhaust nozzle environment wherein the ammonia gas functions to suppress the flash signature.

Growing community of inventors

Huntsville, AL, United States of America

William S Melvin