WO1992013117A1

WO1992013117A1 - Electrochemical desensitization process

Info

Publication number: WO1992013117A1
Application number: PCT/US1992/000551
Authority: WO
Inventors: George Chin; Rex M. Smith; Michael K. Wong; Patrick J. Wagner
Original assignee: Aerojet-General Corporation
Priority date: 1991-01-24
Filing date: 1992-01-24
Publication date: 1992-08-06
Also published as: DE4290097T1; UA26910C2; JPH05504379A; EP0522140A1; JPH0747832B2; GB2258245B; GB2258245A; EP0522140A4; GB9220055D0

Abstract

Potentially hazardous compositions containing solid combustible fuels, oxidants, nitro-containing, nitramine-containing or nitrato-containing compounds and, in many cases, binders are desensitized by electrolysis at low current and over an extended period of time. Compositions containing binders are first oxidized at the anode (17, 18) to cause decomposition and swelling of the binder, followed by further oxidation of the remaining components of the composition or switching of the polarity (46) to cause reduction, as needed. The resulting compositions have a lowered sensitivity to initiation by such external influences as inadvertent impact or inadvertent electrostatic discharge.

Description

ELECTROCHEMICAL DESENSITIZATION PROCESS

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of co-pending application

Serial No. 07/645,382, filed January 24, 1991.

This invention lies in the field of electrochemical processes and equipment in which electrochemical reactions are conducted.

BACKGROUND OF THE INVENTION Compositions containing energetic compounds such as nitratoesters, mtramines and/or other nitro-group-bearing compounds, combustible fuels, oxidants and combinations of these are used for a variety of functions in a wide range of industrial and other types of applications. A problem commonly encountered with the use of such compositions is that they are difficult to dispose of in an ecologically acceptable manner. These compositions have a potential for the accidental or spontaneous initiation of a forceful reaction accompanied by the sudden release of a large amount of energy. Initiation may result from external influences such as an inadvertent impact or an accidental electrostatic discharge, and environmental and safety considerations require such a potential for danger to be reduced or avoided.

SUMMARY OF THE INVENTION

It has now been discovered that compositions of the type described above can be effectively desensitized, and thus rendered much less susceptible to inadvertent initiation, in a nonhazardous and controlled manner by electrolysis. In accordance with this invention, the composition is placed in contact with two electrodes and an electric current is passed from one to the other through the composition. One or more of the active components in the compositions undergoes an electrolytic conversion in an oxidation or reduction reaction (or both) at the appropriate electrode, thereby lowering the susceptibility of the composition to initiation. In certain applications of the invention, the compositions are combinations of nitro-group-bearing compounds, fuels and oxidants, and several reactions occur simultaneously, in which case nitro groups on the nitro-group-bearing compounds are reduced to amino groups or to alcohol ( — OH) groups and nitrogen gas, oxidants are reduced, and fuels are oxidized, all simultaneously. Other components of the composition which are susceptible to oxidation or reduction, such as binder materials and other additives, will also undergo conversion. The current will be continued for such time as needed to desensitize the composition to a degree considered adequate for purposes of reducing hazards associated with disposal. The invention is generally applicable to solid energetic compounds. The invention is most conveniently performed by macerating the solid material and combining it with a liquid to form a sluπy prior to placing it in contact with the electrodes. The liquid will be one which will improve the transport of ions through the composition in response to the electric current, and preferably one which will dissolve one or more of the components of the composition to produce a dissolved electrolyte. The efficiency of the process will generally increase as the contact area between the solid and the liquid increases, and thus, higher degrees of maceration will generally result in improved efficiencies.

In preferred embodiments of the invention where the solid composition contains a binder, the composition is placed in the electrolysis cell closer to one of the two electrodes than to the other, and preferably in contact with the closer electrode. The electrodes are then energized through a polarity switch which enables one to reverse the polarity. The electrode which is closer to the solid composition (ie., the working electrode) is first energized as an anode, thereby causing the binder to oxidize. This oxidation and resulting decomposition of the binder cause the composition to swell, thereby improving access of the ions produced by the electric current to the other components of the composition. The polarity is then either maintained or switched, depending on the remaining materials to be decomposed and the type of decomposition reaction required. For reduction reactions, the working electrode is switched to a negative polarity (cathode), whereas for oxidation reactions, the working electrode is held at a positive polarity (anode). When energetic nitro, nitramine or nitrato compounds are sought to be decomposed, for example, a negative polarity is applied to the working electrode.

Advantages of the invention include the elimination of the need for special solvents otherwise required in the disposal of such materials, the ability of the invention to permit the decomposition of two or more sensitive components simultaneously, the ability to decompose the components with electricity at low current density and voltage, and the ability to conduct the decomposition with simple, readily constructed equipment. Other features, objects and advantages of the invention will become apparent from the description which follows. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a desensitizing processor which can be used in performing the process of the present invention.

FIG. 2 is a block diagram of a system for driving, controlling and monitoring the processor of FIG. 1.

FIG. 3 is a perspective view of a cell which may be used in the practice of the invention and is of a different configuration from that of FIG. 1.

FIG. 4 is a diagram showing the cell of FIG. 3 in combination with electrical and temperature control systems. FIG. 5 is a diagram showing a third type of cell in which the present invention may be practiced.

FIG. 6 is a plot of nitroglycerin content vs. time in a propellant composition undergoing desensitization in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

The present invention is applicable to a wide range of compositions of the type described above, including various formulations of propellants and explosives. Examples are single-base propellants, double-base propellants, cast double-base propellants, crosslinked propellants, single-component and multi-component explosives and plastic-bonded explosives. These compositions typically include explosive components, oxidants, fuels, and binders, the latter including both energetic and nonenergetic substances, including fuel-rich and/or oxidizer-rich binders, and other additives such as plasticizers, bonding agents, extenders, catalysts, stabilizers, lubricants and other types of modifiers, fillers and functional substances. Examples of specific energetic components, including oxidizers, are ammonium nitrate (AN), ammonium perchlorate (AP), ammonium picrate, 2,4-diamino-l,3,5-trinitrobenzene (DATB), diazodinitrophenol (DDNP), diethylnitramine dinitrate (DINA), ethylenedinitramine (EDNA), ethylene glycol dinitrate (EGDN), cyclotetramethylene tetranitramine (HMX), lead azide, lead styphnate, mannitol hexanitrate (MN), mercury fulminate, nitrocellulose (NC), nitroglycerin (NG), nitromethane (NM), pentaerythritol tetranitrate (PETN), picric acid (PA), cyclotrimethylene trinitramine (RDX), trinitrophenylmethylnitramine ("Tetryl"), 2,2,2-trinitroethyl 4,4,4- trinitrobutyrate (TNETB), tetrazene, tetranitromethane (TNM), 2,4,6-trinitrotoluene (TNT), and 2-nitrodiphenylamine (2NDPA). Examples of fuels included in these compositions are aluminum and other metals or metal hydrides. Examples of binders and other additives, which are also part of the fuel, are polysulfides, polyurethanes, polybutadienes, triacetin, resorcinol, and graphite. These lists are not exhaustive, but merely illustrative of the types of materials included in compositions which can be treated in accordance with this invention.

The form in which the composition is desensitized in accordance with this invention is not critical, provided that electric current can pass through the composition. Many compositions to which the invention is applicable are solid in form prior to treatment, and certain of these will be capable of desensitization in solid form, depending on the composition itself and the electrolysis apparatus. In most cases involving solid compositions, however, best results will be obtained by first the composition to a sluπy and performing electrolysis on the slurry. The liquid used to form the sluπy will be any liquid capable of conducting an electric current ionically, preferably a polar liquid capable of dissolving salts, acids or bases to form an ionically conducting electrolyte. It is also preferred that the liquid be one which will partially dissolve one or more of the active components of the composition, Le., those which are the source of the detonation risk. This will help leach out some of the active component and enhance its decomposition when subjected to the electric current

Examples of polar liquids are water and aqueous media in general, low molecular weight alcohols such as methanol, ethanol, propanol, isopropanol, butanol and isobutanol, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Other possibilities and examples will readily occur to those skilled in the art Water is preferred for purposes of low cost, safety and ease of use.

The amount of liquid used to form the slurry is also not critical, and will be selected primarily on the basis of practical considerations of equipment scale, and ease of handling, processing and transferring. In most cases, the proportion of liquid actually used will range from about 30% to about 90% by volume of the slurry, with amounts between about 50% and about 75% preferred.

As an optional variation, additives which are not part of the composition itself may be incorporated in the slurry to enhance and accelerate the electrolysis. Such additives may for example be materials that increase the electrical conductivity of the slurry, and also materials that degrade the nitro-, nitramine- and nitrato- containing compounds present in the composition. Examples of such additives are alkali metal, alkaline earth metal and ammonium hydroxides or other water-soluble inorganic bases, water-soluble acids and salts, and sulfides, sulfates, sulfites and polysulfides of alkali metals, alkaline earth metals and ammonia. Examples of alkali or alkaline earth metals are sodium, potassium, and calcium. Potassium is the most commonly used for nitro compound degradation and thus preferred. Additives of this kind are most conveniently used in solution, dissolved in polar solvents such as methanol, ethanol, acetone or dimethyl sulfoxide. Further optional additives are catalysts for the reactions taking place in the desensitization process. Metal catalysts in combination with hydrogen gas, for example, catalyze the reduction of energetic compounds. An example is iridium, which may be used in the form of iridium oxide, preferably as a coating on the electrode at which hydrogen gas is generated. While the method of performing the electrolysis of the present invention is not critical, and may be varied widely while still obtaining acceptable and effective results, it is preferred that a low current density be used over an extended period of time. The term "current density" is used herein to denote the amount of current per unit area of electrode surface. In processing cells where the two electrodes differ significantly in surface area, the surface area used in determimng the current density is that of the electrode which offers the highest resistance to current flow.

The process is to be conducted under such conditions of time, temperature and current density that the reactions which take place occur in a non- self-propagating manner, __., are not subject to spontaneous acceleration but are driven essentially entirely by the electric current The optimum or preferred current for any particular application of this invention will depend on the scale of the process, including the amount of material to be treated, the size of the equipment and the time period available for the treatment In most cases, however, effective results are obtained with a current density not exceeding about 0.30 amps/cm², preferably not exceeding about 0.20 amps/cm². Currents as low as 0.01 amps/cm² will be useful and practical in certain small scale systems. The preferred range for most systems is therefore about 0.01 amps/cm² to about 0.20 amps/cm², with about 0.01 amps/cm² to about 0.03 amps/cm² particularly preferred. In many cases it will be advantageous to gradually decrease the applied electrode potential (and hence the current) as desensitization proceeds. As the concentration of an energetic compound decreases, the applied potential may be lowered in the direction of the minimum activation potential, since progressively less reducing agent is required. In the optimal practice of the invention, the potential is adjusted at intervals to the lowest potential that will maintain the maximum negative slope for the depletion curve. The temperature is not critical, the only consideration being that the temperature itself not create a hazardous situation or cause any substantial amount of vaporization. While the rate of desensitization increases with increasing temperature, the invention is readily and adequately conducted at ambient or room temperature, ie., 20 to 25°C. Cooling of the system during the process is generally not required, and the temperature will frequently rise due to the electric current itself. In most cases, the rise will not be sufficient to require temperature control. In the preferred practice of the invention, the temperature is maintained at an elevated level. For aqueous systems, a preferred temperature range is above about 140°F (60°C) yet safely below the boiling temperature of 212°F (100°C). Elevated temperature increases the reaction rate and reduces the decomposition activation energy requirements. The increased reaction in the slurry further increases the cell conductivity which lowers the electrode overvoltage requirements. The length of time during which the desensitization is permitted to proceed will be any duration which will achieve the desired degree of desensitization at the current used. In most cases, the duration will be greater than about twenty minutes, preferably greater than about 1 hour, and most preferably greater than about 4 hours. The electrodes may be constructed of any of the materials which are known for use as electrodes. The actual material to be used may be varied widely. Selection of the material for any particular application, however, will be influenced by a number of factors. For example, preferred materials will generally be those which are the least susceptible to degradation from the passage of electric current In certain systems, furthermore, the preferred materials will be those which are inert to the electrochemical reactions which will occur during the process. In certain other systems, it will be preferable to use electrodes which themselves become reduced or oxidized during the process. In still other systems, it will be preferable to use electrodes which absorb reactants or products of the electrochemical reactions occurring in the process.

With these considerations in mind, examples of types of materials from which the electrodes can be formed are metals, graphite, metal oxides and conducting polymers. Examples of specific metals are copper, silver, aluminum, platinum, titanium and zinc. Examples of metal oxides are Pb0₂ (lead dioxide), Mn0₂ (manganese dioxide) and NiFe^ (nickelous ferric oxide). Examples of conducting polymers are polyaniline, polyacetylene and polypyrrole. Each type of electrode will offer advantages for particular types of compositions being treated. For example, in systems where electrolysis results in hydrogen evolution, metals with high hydrogen overpotentials (also referred to as "high hydrogen overvoltages") may be used to reduce or eliminate the release of gaseous hydrogen. For systems where oxidation of the electrode may occur at the anode, metal oxides or noble metals are preferred in order to preserve the anode. Other reasons and motivations and the appropriate selections in each case will be apparent to those skilled in the art.

The configuration and spacing of the electrodes and the design and construction of the electrolysis cell are not critical, and will be varied according to the needs of the system. The cell may for example be a single-vessel cell, a partitioned cell two half-cells. The cell efficiency will depend at least in part on the electrode surface area, since the electrochemical reactions take place at the electrode surfaces. For use on full-scale quantities of material, the electrodes will generally be spaced from about 1cm to about 100cm apart, preferably from about 3cm to about 30cm.

The cell itself may be constructed of any inert material capable of withstanding the operating conditions and pH of the materials treated and used in the process. Nonconductive materials of construction such as plastic will generally be the most prefeπed, although a wide range of other materials may be used as well. Alternatively, the cell may be constructed of a conducting material with the cell walls serving as one of the electrodes. For systems in which the composition being treated is in the form of a slurry, a mechanism for agitation or mixing of the slurry is preferably included, for purposes of keeping the slurry in suspension and of exposing the components of the composition to the electric current in an efficient and uniform manner. It will also be advantageous to periodically or intermittently remove deposited solids from the electrodes to maximize the electrode surface area for exposure to the s iny and thereby optimize the efficiency of the cunent flow. Further optional features include temperature detectors and voltage detectors, which may be placed on or near the electrodes or at any location in the cell, as well as pH probes.

Electrolysis may be conducted using any of a variety of electric cunent profiles. The actual type of cunent may be varied, although certain types may be preferable for treating certain compositions. In general, alternating cunent, direct cunent or pulsed cunent may be used. For alternating cunent the frequency may vary and is not critical. For pulsed cunents, each pulse will be direct cunent. The pulse duration however may vary. A computer is particularly useful for control of pulse switching and duration. The degree to which the composition is electrolyzed in the practice of the invention is also noncritical and may vary. In cases where the composition is being treated for purposes of disposal and must meet specific requirements or conform to regulations before being disposed of, it is only necessary that the composition be electrolyzed to a sufficient degree that such requirements or regulations be met It will generally not be necessary to proceed to substantially full electrolysis of those components which present a hazard, Le., to a degree where at most only trace amounts are present. In most cases, for example, it will be acceptable and sufficient to convert at least 30%, preferably at least about 70%, and preferably at least about 90%, of the nitro groups of the composition to amino groups by the electrolysis. Likewise, it will in most cases be acceptable and sufficient to reduce at least about 30%, and preferably at least about 70%, of the oxidant contained in such compositions.

Turning now to FIG. 1, one example of an electrolytic cell 11 in which the process of the invention may be performed is shown. The sluπy 12 to be desensitized is placed in an open-top vessel 13. The vessel 13 is supported on a turntable 14, electrically powered to rotate. The turntable may be constructed with the capability of being raised or lowered to place it in contact, or remove it from contact, with the other components of the structure entering the vessel through its opening from above.

Placed over the turntable 14 and vessel 13 are a support stand 15, constructed to span the vessel opening. Secured to the stand are a stiner bar 16 and electrodes 17, 18, arranged to extend downward into the interior of the vessel 13 and thereby be submerged in the sluπy 12. The stiner bar 16 is rigidly attached to a first tier 19 of the support stand and remains stationary as the turntable 14 rotates. The apparatus shown in FIG. 1 further includes a mechanism for scraping the electrodes clean of deposited solids. The electrodes in this example are rod-shaped, and the scraping mechanism consists of a pair of scraper cages 22, 23, each sunounding one of the electrodes with a small gap as clearance. The scraper cages are rigidly affixed to the first tier 19 of the support stand, whereas the electrodes 17, 18 are mounted for vertical movement inside the scraper cages. The electrodes extend from a common yoke 24 which is secured in a movable fashion to a second tier 25 of the support stand. The electrodes pass through openings in the first tier 19 of the stand above the scraper cages 22, 23, and extend into the space inside the scraper cages. The fit is sufficiently loose to permit movement of the electrodes within the cages, but with a sufficiently small gap that effective removal of deposited solids is achieved by the movement

The yoke 24 which joins the electrodes is suspended from the second tier 25 of the support stand by a movable rod 26 whose motion is controlled by an air cylinder 27, which may for example be a double-acting short stroke actuator cylinder. The movable rod 26 is shown in the extended position. Upon command by the appropriate signal, the actuator cylinder 27 retracts the rod 26, moving the electrodes upward inside the stationary scraper cages. The actuator cylinder holds the rod in this retracted position until a further signal actuates the return of the rod to the extended position. It will be clear from the drawing that only a short range of motion of the rod is needed for the electrodes to move sufficiently to be scraped by the scraper cages.

FIG. 2 represents a system diagram for the operation of a desensitizing processor of the type shown in FIG. 1. The electrolytic cell 11 is shown, with the electrodes 17, 18. Also included are a pH probe 31 extending into the slurry, and an associated pH monitor 32; a voltage sensor 33 or pair of sensors, one attached to each of the scraper cages, and an associated voltage gradient monitor 34 for monitoring the voltage gradient between the electrodes; a temperature detector 35 or pair of detectors, one attached to each scraper cage, and an associated temperature gradient monitor 36 for monitoring the temperature gradient in the slurry; a heat exchanger 37 and an associated temperature control system 38 controlled by the temperature gradient monitor 36; a turntable drive 39 controlled by a turntable controller 40; and the electrode actuator cylinder 27 controlled by an actuator controller 41.

Electric power supplied by a power source 44 is controlled by series cunent regulators 45 and a polarity switching controller 46. A gas analyzer system 47 is also included to monitor the gas composition above the slurry. Each of these units is governed by a process controller and alarm system 48, which is in turn controlled by a computer 49 equipped with a data/alarm display 50, a control console 51, and a unit for data documentation 52. An automation unit 53 further provides the system with the capability of automated operation.

A second example of an electrolytic cell in which the invention may be performed is shown in FIG. 3, and this second cell is shown together with power supply and temperature control systems in FIG. 4. As shown in FIG. 3, this cell is a rectangular open-top tank 61, preferably made of a transparent electrically and chemically inert material such as glass. One electrode 62 is a planar rectangular electrode positioned horizontally at the bottom of the tank, and the other electrode 63 is a second planar rectangular electrode of the same size as the first, positioned horizontally inside the tank at a level above the first. The sluπy of macerated propellant (or similar composition) 64 is placed above the lower electrode 62, leaving a gap 65 between it and the upper electrode 63. The gap is filled with water 66 which also covers the upper electrode 63. Liquor from the propellant maceration operation may be used as the water. The two electrodes are electrified by appropriate voltage supply lines 67, 68. In the anangement shown, the lower electrode 62 serves as the cathode and the upper electrode 63 serves as the anode.

Either electrode may be a continuous solid plate or a plate of grill-type or honeycomb-type structure, in all cases preferably flat. Since gns bubbles are normally generated during the electrolysis, it is preferable that the upper plate be of a grill-type or honeycomb-type structure to permit the gas bubbles to escape. Alternatively, the upper plate may be a continuous solid tilted slightly to accelerate the escape of the bubbles. The plate size is not critical for either of the two plates. Successful results have been obtained with plate sizes ranging from 2 to 40 square inches (13-258cm²), although larger plates may also be successfully used.

The FIG. 4 drawing shows the cell inside a temperature control jacket 71. Circulation of the coolant through the jacket and control of the coolant temperature is achieved by a heating/cooling unit 72 which relies on a thermocouple probe 73 extending inside the cell, the probe being coated with a layer of non- conductive material. The unit will contain a pump, controls for setting a setpoint temperature, and a heating and/or cooling mechanism, and may be of conventional construction and operation. The voltage supply lines 67, 68 are fed by a power supply 74 through a polarity switch 75 which permits the operator to select which of the electrodes is the anode and which the cathode and to switch back and forth between them.

The system shown in FIGS. 3 and 4 may be operated in a variety of ways, depending on the nature of the propellant being treated and what types of desensitization reactions are required. In a typical operation, macerated propellant is placed on the lower electrode 62 in a layer of uniform thickness, and the upper electrode 63 is then suspended (by conventional suspending means) above the propellant layer. The gap 65 between the upper surface of the propellant layer and the lower surface of the upper electrode will be at least about 0.5 inch (1.27cm) in most cases to provide best results, and preferably about 1.0 inch (2.54cm).

A third example of an electrolytic cell system is shown in FIG. 5. This system consists of two half cells, which may be refened to for convenience as a primary half cell 81 and a secondary half cell 82. A working electrode 83 extends into the primary half cell 81, and a reference electrode 84 extends into the secondary half cell 82. The two half cells are connected by an electrolyte bridge 85. The electrodes and electrolyte bridge are of conventional materials and construction. Electrical leads 86, 87 supply voltage to the electrodes from a power supply 88, and the polarity of the leads is controlled by a polarity switch 89, as in FIG. 4. Macerated propellant 90 is placed only in the primary half cell 81. The secondary half cell 82 and the remainder of the primary half cell are filled with water, or with liquor left over from the maceration of the propellant, or any other conductive medium.

In a typical operation of a system such as that shown in FIG. 5, the desensitization process is begun by switching the polarity switch 89 to connect the electric supply line 87 which supplies voltage to the working electrode 83 to the positive pole of the power supply 88, causing the primary cell to function as an anode, while simultaneously connecting the reference electrode 84 to the negative pole of the power supply. The anodic reaction in the primary half cell causes the oxidizing agents in the macerated propellant to attack the binder material in the propellant causing the propellant to swell. The swelling provides an increased access to the energetic compounds that were bound with the binder material. Once swelling has occuned, the polarity of the electrodes is reversed by the polarity switch to produce a cathodic reaction in the primaiy half cell. This results in the desensitization of the energetic compounds. The following examples are offered strictly for purposes of illustration. They are intended neither to limit nor to define the invention in any manner.

EXAMPLE 1 This example illustrates the desensitization of a propellant composition >^" by use of the present invention. The propellant composition was as follows:

100.0

To conduct the desensitization, the propellant composition was macerated and combined with water to form a slurry, of which the final water content was 45% by weight The slurry was then placed in an electrolytic cell apparatus consisting of a 400-mL beaker of nonconductive material with two aluminum electrodes spaced 4cm apart and a source of direct cunent. The amount of slurry charged to the beaker was 155mL. Direct cunent was applied at a cunent density of 0.02 amps/cm², and maintained for four days. During this time, the mixture was manually mixed three times per day and water was added as necessary to maintain the initial liquid level.

At the end of the four-day period, the cunent was turned off and the slurry removed from the plastic container. Water was then removed from the slurry by decantation and evaporation, to return the propellant materials to solid form. Analyses and standard sensitivity tests were then performed to compare the treated material with the starting material prior to being formed into the slurry. The analyses included determinations of the levels of ammonium perchlorate, HMX and NG, and the sensitivity tests included a Naval Ordnance Laboratory Card Gap Test and a Bureau of Mines Dropweight Impact Test Each of the sensitivity tests was conducted according to standard procedures well known and readily available to those skilled in the art The Card Gap Test was conducted using zero cards. The term "positive" in the Card Gap Test indicates detonation under the conditions used in the test and the term "negative" indicates lack of detonation. In the Impact Test, the value given is the minimum height from which a 2-kg weight dropped onto the sample caused the sample to detonate, an increase in the value representing a loss in sensitivity. The results of all tests comparing the material before and after the electrolysis are listed in Table II.

The data in Table II clearly show the loss in sensitivity brought about by electrolysis practiced in accordance with the present invention.

EXAMPLE 2

This example is a further illustration of the desensitization of a propellant composition by use of the present invention, this time using a catalyst and showing the depletion rate of nitroglycerin.

The propellant composition was the same as that used in Example 1, and as in Example 1, the composition was macerated and combined with water to form a sluπy having 45% by weight water. The sluπy was placed in four cells similar to those depicted in FIG. 1; the volumetric capacity of each cell was 1 liter, and the amount of slurry charged to each cell was 600mL. Each cell contained an anode and cathode, each 6 inches (15.2cm) in length and 0.5 inch (1.3cm) in diameter, and spaced apart by a distance of 2 inches (5.1cm). The cathode was a titanium electrode with an iridium oxide coating. Direct cunent at 1.3 amps was applied and maintained for a period of time which differed for each cell - 2, 4, 8 and 24 hours in length, respectively. During each period, the cell and its contents were left undisturbed; no mixing occuned. The cunent was then turned off and the slurries were removed from the cells and dried to solid form. Analyses and standard sensitivity tests were performed on each treated and dried sample to compare the treated material with samples of material identical to the starting material before it had been formed into a sluπy. The analyses included a determination of the weight percent of NG and a Bureau of Mines Dropweight Impact Test, according to the same procedure used in Example 1. The results of these tests are shown in Table III below, and the nitroglycerin depletion in terms of percent of the original amount is plotted in FIG. 6.

TABLE III Results of Desensitization

Nitroglycerin, weight % Impact, cm:

The data in Table III clearly show a gradual loss in sensitivity attributable to the process of the invention.

The apparatus and system depicted and described herein are merely illustrative. Modifications, variations, and alternative anangemer s and designs which, although differing from that described above, still embody the basic concepts and spirit of the invention will be readily apparent to those skilled in the art.

Claims

WHAT IS CLAIMED IS:

1. A process for treating a composition containing one or more energetic compounds tending upon initiation to produce pressurized gaseous products, to substantially reduce the sensitivity of said composition to inadvertent initiation, said method comprising: (a) placing said composition in electrical contact with a pair of electrodes to form a continuous path for the passage of an electric cunent between said electrodes; and

(b) passing an electric cunent between said electrodes through said composition, thereby performing by electrolysis, in a non- propagating manner, at least one electrochemical reaction resulting in the conversion of said energetic compounds to less energetic or non- energetic compounds.

2. A process in accordance with claim 1 in which said energetic compounds are nitro-group-bearing compounds, and said electrochemical reaction of step (b) is a reaction selected from the group consisting of (i) the conversion of at least a portion of the nitro groups of said nitro-group-bearing compounds to amino groups, and (ii) the conversion of at least a portion of said nitro groups to alcohol groups and nitrogen gas.

3. A process in accordance with claim 1 in which said composition contains solid combustible fuel, solid oxidant and solid or liquid nitro-group-bearing compounds, and said electrochemical reaction of step (b) is one or more reactions selected from the group consisting of (i) the oxidation of at least a portion of said fuel, and (ii) the reduction of at least a portion of said oxidant, (iii) the conversion of at least a portion of the nitro groups of said nitro-group-bearing compounds to amino groups, and (iv) the conversion of at least a portion of said nitro groups to alcohol groups and nitrogen gas.

4. A process in accordance with claim 3 further comprising combining said composition with a liquid to form a slurry prior to step (a), and in which steps (a) and (b) are performed with said composition in slurry form.

5. A process in accordance with claim 4 in which said liquid is a member selected from the group consisting of water, low molecular weight alcohols and ketones.

6. A process in accordance with claim 4 in which further comprising mixing said slurry continuously during step (b).

7. A process in accordance with claim 4 in which said liquid is water.

8. A process in accordance with claim 4 in which said liquid is water and in which said composition is further combined with a water-soluble inorganic base, acid or salt in forming said sluπy.

9. A process in accordance with claim 1 in which said energetic compounds are nitro-group-bearing compounds, and said composition is a liquid solution of said nitro-group-bearing compounds.

10. A process in accordance with claim 1 in which step (b) comprises applying direct cunent between said electrodes.

11. A process in accordance with claim 1 in which step (b) comprises applying alternating cunent between said electrodes.

12. A process in accordance with claim 1 in which step (b) comprises applying pulses of direct cunent between said electrodes.

13. A process in accordance with claim 3 in which step (b) comprises converting at least a portion of the nitro groups in said nitro-group-bearing compounds to amino groups or to alcohol groups and nitrogen gas.

14. A process in accordance with claim 3 in which step (b) comprises oxidizing at least a portion of said fuel.

15. A process in accordance with claim 3 in which step (b) comprises reducing at least a portion of said oxidant.

16. A process in accordance with claim 3 in which step (b) comprises converting at least a portion of the nitro groups in said nitro-group-bearing compounds to amino groups or to alcohol groups and nitrogen gas, and reducing at least a portion of said oxidant.

17. A process for treating a composition containing one or more energetic compounds bound together by a polymeric binder, said energetic compounds including at least one member selected from the group consisting of nitro- group-bearing, nitramine-group-bearing and nitrato-group-bearing compounds, to substantially reduce the sensitivity of said composition to inadvertent initiation, said method comprising:

(a) placing said solid composition in contact with a first electrode in an electrolytic cell which further contains a liquid medium connecting said first electrode and a second electrode in said cell; (b) with said first electrode energized as an anode, passing an electric cunent between said first and second electrodes to at least partially oxidize said binder; and

(c) subsequent to step (b), energizing said first electrode as a cathode and passing an electric cunent between said first and second electrodes to reduce at least a portion of said energetic compounds.

18. A process for treating a composition containing one or more energetic compounds bound together by a polymeric binder, said energetic compounds decomposable by oxidation, to substantially reduce the sensitivity of said composition to inadvertent initiation, said method comprising: (a) placing said solid composition in contact with a first electrode in an electrolytic cell which further contains a liquid medium connecting said first electrode and a second electrode in said cell; and (b) with said first electrode energized as an anode, passing an electric cunent between said first and second electrodes to at least partially oxidize said binder and to at least partially oxidize said energetic compounds.

19. A process in accordance with claims 17 or 18 in which step (a) comprises placing said solid composition in contact with said first electrode only.

20. A process in accordance with claims 17 or 18 in which said liquid medium is a member selected from the group consisting of an aqueous medium, low molecular weight alcohols and ketones.

21. A process in accordance with claims 17 or 18 in which said liquid medium is an aqueous medium.