Patent Application
20240200922
The present invention relates generally to disposal of ammunition, and specifically to a method and apparatus for electrochemical ammunition disposal and material recovery.
Armed forces, police organizations, and other armed entities world-wide possess large quantities of surplus and obsolete ammunition. Existing ammunition disposal processes have serious disadvantages. For example, ocean dumping and disposal in landfills are no longer environmentally acceptable. Disassembly and pre-treatment to remove or render safe the explosive components is costly and requires extensive safety measures. The same concerns apply to destruction of ammunition by detonation methods, which further make component separation and recovery difficult. Additionally, long-term storage of surplus and obsolete ammunition is neither safe nor cost-effective.
U.S. Pat. No. 10,514,242 discloses a method and apparatus for electrochemical ammunition disposal and material recovery, ammunition cartridges are placed in an acidic aqueous solution that is in contact with a cathode and an anode. The ammunition cartridges have a casing that includes an alloy of copper and zinc. The ammunition cartridges are agitated in the acidic aqueous solution as a voltage is applied between the anode and the cathode. The applied voltage is effective to oxidize and dissolve zinc from the copper-zinc alloy. Copper metal derived from the alloy can be recovered as a solid, and zinc ion derived from the alloy can be recovered as a solution. The apparatus disclosed can be an anode and cathode simply hanging into an acidic solution on opposite sides of a container or can comprise a rotating container for agitating the ammunition where the container is at least partially submerged in the acid bath, and where the container has a solution-permeable outer layer of electrically insulating material substantially surrounding other components of the container and defining a volume, an anode comprising lead and disposed on an inner surface of the outer layer or within the volume defined by the outer layer, and a cathode comprising copper, disposed within the volume defined by the outer layer, and physically separated from the anode.
A need remains for a more efficient method and apparatus.
Disclosed herein is an apparatus for electrochemical ammunition disposal and material recovery, the apparatus comprising: a vessel for holding an acidic aqueous solution; an anode at least partially immersed in the acidic aqueous solution; physically separated from the anode, a movable cathode at least partially immersed in the aqueous solution, wherein the movable cathode in a first position has a first surface which is not-immersed in the aqueous solution; a cleaning implement to remove material on the first surface of the cathode; and a power supply for applying a voltage between the anode and the cathode.
Also disclosed herein is a method for recovery of materials from and disposal of ammunition comprising providing a vessel containing an acidic aqueous solution and a rotatable cathode which is partially immersed in the acidic aqueous solution where rotation of the cathode causes a portion of the cathode to be immersed and another portion to not be immersed in the acidic aqueous solution; placing ammunition in the acidic aqueous solution; wherein either the ammunition or a separate metal element at least partially immersed in the acidic aqueous solution serves as an anode; and wherein the ammunition comprises at least one metal which dissolves in the acidic aqueous solution when a voltage is applied and which has a positive standard reduction potential; providing a voltage between the anode and the cathode to dissolve the at least one metal and deposit the at least one metal onto the cathode; cleaning the deposited at least one metal from the portion of the cathode not immersed in the acidic aqueous solution.
The invention will be more fully understood by reference to the detailed description, in conjunction with the figure.
The present invention is directed towards electrochemical ammunition disposal and material recovery. While the method and apparatus of electrochemical ammunition disposal and material recovery disclosed in U.S. Pat. No. 10,514,242 had advantages over thermal methods of recovery of metals, means of recovery of metals from the cathode is not specifically addressed and could be inefficient and labor intensive. For instance, in the embodiment shown in
The method and apparatus disclosed herein can be used to separate the components in ammunition cartridges for further materials recovery. The method and apparatus disclosed herein are useful for disposal of small arms ammunition with brass cartridges, although it may be adapted to other types of ammunition.
In general, a cartridge (also called a round or a shell) is a type of ammunition packaging a bullet or shot, a propellant substance, and a primer within a metallic, paper, or plastic case that is precisely made to fit within the firing chamber of a firearm. The primer is a small charge of an impact-sensitive or electric-sensitive chemical mixture that can be located at the center of the case head, inside a rim, or in a projection such as in a pinfire or teat-fire cartridge. Military and commercial producers continue to pursue the goal of caseless ammunition. Some artillery ammunition uses the same cartridge concept as found in small arms. In other cases, the artillery shell is separate from the propellant charge.
Components of ammunition intended for machine guns, rifles and pistols may be divided into explosive materials (gunpowder), projectiles (lead bullet heads) and cartridge cases (e.g., metal shells, particularly brass shells). Brass is an alloy of copper and zinc. The method and apparatus disclosed herein enable separation of the four components of lead, gunpowder, metals from the cartridges (e.g., copper and zinc) for further recovery. While the apparatus and method can be used for disposal of small arms ammunition as discussed above, it is also applicable to larger scale ammunition types, and the electrochemical process parameters can be modified to recover metals other than or in addition to copper, zinc, and lead. Such other metals can include tin (e.g., as an alloy with lead), nickel (e.g., as an alloy with copper), tellurium (e.g., as an alloy with copper), iron (e.g., in a steel jacket), tungsten and depleted uranium (e.g., for armor piercing), among others. The skilled electrochemist can adjust the electrochemical conditions of the method to recover such other metals. Generally, metals in alloys behave in one of three ways under the process conditions: (1) they dissolve in the acidic aqueous solution, (2) they dissolve from the alloy and redeposit on the cathode as metal, or (3) they do not dissolve, but because other metal(s) in the alloy dissolve, they are transformed to a typically powdered form of metal, which collects at the bottom of the container holding the acidic aqueous solution. For example, tellurium will not dissolve and will collect at the bottom of the container. As another example, zinc will dissolve in the acidic aqueous solution, from which it can be recovered by adding a soluble phosphate salt to the acidic aqueous solution, which creates a zinc phosphate precipitate. Metals that can dissolve and that have a positive standard reduction potential, such as copper, can redeposit on the cathode.
Water can corrode metal shells, particularly, brass shells over a long period of time. Acids and caustics promote the corrosion process. The method and apparatus disclosed herein use electric current to enhance and accelerate the dissolution of a shell in a diluted acid solution, thus releasing energetic material and separating the metals.
The apparatus includes a vessel for holding an acidic aqueous solution. The vessel can be structured so as to be able to receive a cathode that is at least partially immersed in the acidic aqueous solution. The vessel can be structured so as to be able to receive an anode that is at least partially immersed in the acidic aqueous solution. The vessel can be structured so as to be able to receive a container having an outer layer that is permeable to the acidic aqueous solution. The vessel can include a drain mechanism to facilitate removal of acidic aqueous solution comprising dissolved metals for later recovery.
The acidic aqueous solution can be a solution suitable for the ammunition being processed. The acidic aqueous solution can be a strong acid, preferably a strong inorganic acid. Suitable acids include, for example, nitric acid, sulfuric acid, and combinations thereof. The concentration of acid in the acidic aqueous solution can be, for example, 2 to 30 weight percent, or 2 to 25 weight percent, or 2 to 20 weight percent, or 5 to 20 weight percent, based on the total weight of the acidic aqueous solution. For example, the acidic aqueous solution can comprise sulfuric acid at a concentration of 5 to 20 weight percent.
The cathode is partially immersed in the acidic aqueous solution but is moveable to a position such that a portion of the cathode is not immersed in the acidic aqueous solution so as to be able to readily remove metal that has deposited on the cathode. Particularly, the cathode can be rotatable such that while a portion remains immersed in the acidic aqueous solution another portion is not immersed and a cleaning implement can be used to remove a metal, such as copper, deposited on the cathode.
The cleaning implement can be a cleaning edge that can scrape a surface of the cathode that is not immersed in the acidic aqueous solution. For example, for a cylindrical cathode a cleaning edge can be placed in contact with a portion of the cathode not immersed in the acidic aqueous solution and the metal scraped off by rotation of the cathode. Alternatively, or in addition to such cleaning edge, if the metal is not plated onto the cathode, a vacuum, a washing device, or a combined washing and aspiration device can be as the cleaning implement. The rotating cathode has the benefit of enabling the electrochemical separation to continue while simultaneously recovering the metal deposited on the cathode. For example, copper will deposit on the cathode such that it can be removed and collected by operation on the moveable cathode with the cleaning implement. The copper removed can be transferred from the cleaning implement (e.g., cleaning edge) to a collection container. The cleaning implement should be located such that deposited metal removed from the cathode does not fall back into the aqueous acidic solution. For example, a cleaning edge could be located at an edge of the vessel and extending to contact the cathode. As another example, shielding between the cleaning implement and the acidic aqueous solution could be used.
Since power is applied to the cathode, a cleaning edge preferably comprises an electrically insulating contact surface. Suitable materials for a cleaning edge include the electrically insulating material having a volume resistivity of at least 1012 ohm-centimeters, or at least 1013 ohm-centimeters, or 1012 to 1016 ohm-centimeters. Examples include certain polymers or ceramic materials.
The cathode comprises a conductive material. The specific conductive material can be selected for the chemistry of the ammunition to be processed. For example, the cathode can comprise titanium, stainless steel, or copper.
If the cathode is rotated to expose a portion above the acidic aqueous solution to the cleaning implement for removal of material, a motor can be provided to facilitate such rotation.
The apparatus includes an anode. The ammunition itself could function as the anode when made of a conductive metal and connected to a power source to apply the necessary voltage between the anode and cathode. For example, such ammunition could be hung into the acidic aqueous solution. Alternatively, a separate anode can be provided and at least partially immersed in the acidic aqueous solution. An anode in the apparatus and method disclosed herein is a conductive material. The specific conductive material can be selected for the chemistry of the ammunition to be processed. For example, the anode can comprise lead or stainless steel. The anode can be chosen from a conductive material which is inert to, or resistant to, or substantially resistant to the acidic aqueous solution.
An agitator can be included to agitate pieces of ammunition that are immersed in the acidic aqueous solution to be processed for recovery of components. Agitating the ammunition (e.g., cartridges) can cause them to make physical contact with the anode, which can increase the electrical efficiency of the method.
For example, a hollow, solution-permeable container can be used to hold the ammunition. This container can be moved (e.g., rotated) to provide agitation of the ammunition. The solution-permeable container can comprise an anode. An anode can be located within the hollow region of the hollow, solution-permeable container. The anode can be in contact with the ammunition in the container. For example, an anode can comprise an anodic material dangling into the container from a center axis. For example, the ammunition to be processed connected to an electric source through a conductive material (e.g., anode dangling into the container) can function as an anode. For example, the anode can comprise a conductive material, such as stainless steel, connected to an electrical source by a coated wire. The coating on the wire can provide protection of the conductive material from the acidic aqueous solution. The coated wire can hang or dangle into the container. The container can comprise an electrically insulating material. For example, the electrically insulating material can comprise a polymer having a volume resistivity of at least 1012 ohm-centimeters, or at least 1013 ohm-centimeters, or 1012 to 1016 ohm-centimeters. Solution permeability can be provided, for example, by small pore in the shell (also referred to as wall or outer layer) of the container. Pore size should be small enough that solids remaining after processing do not pass through the pores but that enable adequate fluid flow of the acidic aqueous solution and dissolved metals into the rest of the vessel. For example, pore size can be from ⅛ inch to ½ inch or to ⅜ inch to ¼ inch or to 3/16 inch (or from 3 mm up to 12 mm or up to 9 mm, or up to 6 mm or up to 4.5 mm). The container can be in the shape of a cylindrical drum or polygonal drum.
The apparatus can include a lift device to move the hollow, solution permeable container into and out of the acidic aqueous solution to load the ammunition for recovery and to unload solids (e.g., lead) remaining in the container after the electrochemical processing.
A power supply is connected to the cathode and anode and used to apply a voltage between the anode and the cathode. Applying a voltage between the anode and the cathode facilitates oxidation and dissolution of the alloys in the ammunition—e.g., oxidizing and dissolve zinc from the alloy comprising copper and zinc. The voltage can be varied to achieve a desirable current, which in turn is proportional to the disposal rate of the ammunition. In some embodiments, the voltage between the anode and the cathode is 0.5 to 50, or 0.5 to 20 volts, or 1 to 10 volts, or 1 to 5 volts. The power supply can be a direct current power supply connected to the anode and cathode. A current can thus be supplied through the acidic aqueous solution. For example, the current can be 1 to 20 or 1 to 5 amps.
The skilled electrochemist understands that the process parameters of voltage, anode surface area, cathode surface area, and anode-cathode separation are interrelated and can be adjusted to provide a desired current.
As shown in
There is no particular limit to the size or quantity of the ammunition cartridges because the method and apparatus are scalable. In some embodiments, at least a portion of the ammunition cartridges have a caliber of 0.1 to 2 or greater (corresponding to a barrel diameter of 2.54 to 50.8 millimeters, or greater); or a caliber of 0.2 to 1 (corresponding to a barrel diameter of 5.08 to 25.4 millimeters), or 0.2 to 0.5 (corresponding to a barrel diameter of 5.08 to 12.7 millimeters).
The method is suitable for whole ammunition. For example, at least a portion of the ammunition cartridges can comprise a bullet, a primer, and gunpowder in addition to the alloy comprising copper and zinc. At least a portion of bullet-derived lead, at least a portion of the primer, and at least a portion of the gunpowder can each recovered as solids. In one specific example, the ammunition cartridges each independently have a caliber of 0.1 to 2; at least a portion of the ammunition cartridges further comprise a bullet comprising lead, a primer, and gunpowder; the acidic aqueous solution comprises sulfuric acid at a concentration of 5 to 20 weight percent; and at least a portion of bullet-derived lead, at least a portion of the primer, and at least a portion of the gunpowder are each recovered as solids.
The anode and the cathode are physically separated. An effective physical separation of the anode and the cathode will depend on the scale of the apparatus and can be determined by the skilled person. In some embodiments, physical separation of the anode and the cathode is at least 2 centimeters, or at least 5 centimeters, or at least 10 centimeters.
The invention includes at least the following aspects.
Aspect 1: An apparatus for electrochemical ammunition disposal and material recovery, the apparatus comprising: a vessel for holding an acidic aqueous solution; an anode at least partially immersed in the acidic aqueous solution; physically separated from the anode, a movable cathode at least partially immersed in the aqueous solution, wherein the movable cathode in a first position has a first surface which is not-immersed in the aqueous solution; a cleaning implement to remove material on the first surface of the cathode; and a power supply for applying a voltage between the anode and the cathode.
Aspect 2: The apparatus of Aspect 1 wherein the cleaning implement is a cleaning edge that is placed against the first surface, such that, by relative movement of the cathode against the cleaning edge, material on the surface can be removed from the cathode.
Aspect 3: The apparatus of Aspect 2 wherein the cathode is cylindrical and is moveable against the cleaning edge by rotation.
Aspect 4: The apparatus of Aspect 2 or 3 wherein the cleaning edge is positioned such that material removed from the cathode surface can be collected in a collection container and is prevented from re-entering the vessel.
Aspect 5: The apparatus of any of Aspects 2-4 wherein the cleaning edge is electrically insulating, preferably having a volume resistivity of at least 1012 ohm-centimeters.
Aspect 6: The apparatus of any of the preceding claims having a hollow, solution permeable container 20 having the anode disposed therein, preferably wherein the anode comprises a piece of conductive metal electrically connected to a power source by a coated wire which is dangling into the hollow-solution permeable container, where the piece of conductive metal is physically and electrically connected to the coated wire.
Aspect 7: The apparatus of Aspect 6 wherein the hollow, solution permeable container comprises a porous, electrically insulating shell, preferably comprising an electrically insulating polymer having a volume resistivity of at least 1012 ohm-centimeters.
Aspect 8: The apparatus of Aspect 6 or 7 wherein the hollow, solution permeable container has a first end and a second end and a perimeter surface extending from the first end to the second end and the hollow-solution permeable container, preferably a cylindrical or polygonal drum, more preferably a polygonal drum such as octagonal or hexagonal, is mounted with the first end and second end horizontal to each other and to enable rotation of the container to provide agitation of contents of the container.
Aspect 9: The apparatus of Aspect 8 further comprising a motor to rotate the hollow-solution permeable container.
Aspect 10: The apparatus of any of the preceding Aspects wherein the anode comprises ammunition to be disposed.
Aspect 11: The apparatus of any of the preceding Aspects comprising an agitator to agitate ammunition to be disposed in the acidic aqueous solution.
Aspect 12: The apparatus any of the preceding Aspects comprising a motor to rotate the cathode.
Aspect 13: The apparatus of any of the preceding Aspects comprising a drain for the vessel.
Aspect 14: The apparatus of any of the preceding Aspects wherein the acidic aqueous solution comprises sulfuric acid, preferably at a concentration of 5 to 20 weight percent, based on the weight of the acidic aqueous solution.
Aspect 15: The apparatus of any of the preceding Aspects wherein the anode comprises stainless steel.
Aspect 16: The apparatus of any of the preceding Aspects, wherein the cathode comprises stainless steel.
Aspect 17: An apparatus for electrochemical ammunition disposal and material recovery, the apparatus comprising: a vessel for holding an acidic aqueous solution; a hollow, solution permeable container capable of holding ammunition wherein an anode which is at least partially immersed in the acidic aqueous solution is located within the hollow solution permeable container and electrically connected to a power source by a coated wire dangling into the hollow, solution permeable container the coated wire being physically and electrically connected to the anode, and wherein the hollow, solution-permeable container has a first end and a second end and a perimeter surface extending from the first end to the second end as is mounted with the first end and second end horizontal to each other and to enable rotation of the container on an axis from the first end to the second end to provide agitation of contents of the container and where a door in the container, for example one of the ends, can be open to enable placement and removal of ammunition from the hollow, solution permeable container; physically separated from the hollow, solution permeable container, a movable cylindrical cathode at least partially immersed in the aqueous solution, wherein the movable cathode in a first position has a surface which is not-immersed in the aqueous solution; a cleaning edge that is placed against the surface, such that, by rotation of the cathode against the cleaning edge, material on the surface can be removed from the cathode; a power supply for applying a voltage between the anode and the cathode, and at least one motor for rotating the cathode and the anode.
Aspect 18: A method for recovery of materials from and disposal of ammunition comprising providing a vessel containing an acidic aqueous solution and a rotatable cathode which is partially immersed in the acidic aqueous solution where rotation of the cathode causes a portion of the cathode to be immersed and another portion to not be immersed in the acidic aqueous solution; placing ammunition in the acidic aqueous solution; wherein either the ammunition or a separate metal element at least partially immersed in the acidic aqueous solution serves as an anode; and wherein the ammunition comprises at least one metal which dissolves in the acidic aqueous solution when a voltage is applied and which has a positive standard reduction potential; providing a voltage between the anode and the cathode to dissolve the at least one metal and deposit the at least one metal onto the cathode; rotating the cathode so a portion that was immersed is not immersed; and cleaning the deposited at least one metal from the portion of the cathode not immersed in the acidic aqueous solution.
Aspect 19: The method of Aspect 18 where cleaning step comprises moving the cathode against an electrically insulating cleaning edge, preferably rotating the cathode.
Aspect 20: The method of Aspect 18 or 19 wherein the ammunition comprises an alloy of copper and zinc.
Aspect 21: The method of any one of Aspects 18-20 wherein the acidic aqueous solution comprises sulfuric acid.
Aspect 22: The method of any one of Aspects 18-21 wherein placing the ammunition in the acidic aqueous solution comprises placing the ammunition in a solution-permeable container and placing the container in the acidic aqueous solution.
Aspect 23: The method of Aspect 22 further comprising moving the solution-permeable container is moved to agitate the ammunition in the acidic aqueous solution.
Aspect 24: The method of Aspect 23 wherein the movement comprises rotation.
Aspect 25: The method of any one of Aspects 18-24 wherein the ammunition comprises a casing, a casing comprising an alloy comprising copper and zinc; a bullet comprising lead; a primer; and gunpowder.
Aspect 26: The method of Aspect 25 wherein at least a portion of bullet-derived lead, at least a portion of the primer, and at least a portion of the gunpowder are each recovered as solids.
Aspect 27: The method of any one of Aspects 18-26 wherein the metal deposited on the cathode comprises copper.
Aspect 28: The method of any one of Aspects 18-27 wherein zinc ion is recovered in acidic aqueous solution.
Aspect 29: The method of any one of Aspects 18-28 wherein the cleaning occurs while applying the voltage.
Aspect 30: The method of any one of Aspects 18-28 wherein the cleaning occurs after applying the voltage.
The term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A, X employs B, or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. Moreover, articles “a” and “an” as used in the subject specification and annexed drawings should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt. % to 25 wt. %,” etc.). Moreover, stated upper and lower limits can be combined to form ranges (e.g., “at least 1 or at least 2 weight percent” and “up to 10 or 5 weight percent” can be combined as the ranges “1 to 10 weight percent”, or “1 to 5 weight percent” or “2 to 10 weight percent” or “2 to 5 weight percent”).
The disclosure may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The disclosure may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/025482 | 4/20/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63183669 | May 2021 | US |
