Nestled within 100 square miles in Southern Indiana, Crane Army Ammunition Activity supports the hi-tech mission of destroying obsolete munitions for the Department of Defense. For more than two decades, white phosphorous rounds have been successfully demilitarized within a closed system and converted into agriculture fertilizer, both ensuring the future readiness for the storage of increasingly modernized munitions and providing a product that supports America's farmers.
An obstacle presented itself in an otherwise smooth operation when the need to demilitarize red phosphorous rounds became imperative in continuing future readiness for the Joint Warfighter. Due to small molecular differences that caused differing burning points, Crane Army engineers had to work to design a process that would ensure the safe extraction of red phosphorous so that the mission could continue on for decades to come.
The History
In 1989, the mission to demilitarize white phosphorous in a closed system and turn it into phosphoric acid was brought to Crane Army Ammunition Activity. Since that time, the white phosphorous-to-phosphoric acid conversion plant has been considered a successful mission. Not only does it demilitarize an obsolete munition in a safe and environmentally friendly way, it produces two revenue generating materials: agricultural fertilizer and metal for recycling.
In one day, the facility produces 48,000 pounds of phosphoric acid. To do this, a hole is punched into the munition containing white phosphorous, and is inserted into a modified rotary kiln furnace via a gravity feed system. Two 75 horsepower blowers are used to maintain a negative pressure on the material, which draws the heated vapors through a flow/counter flow hydration system to produce the phosphoric acid concentration. The facility's design to meet environmental standards in a profitable way made it a flagship in the search for closed system demilitarization processes.
About twenty years later, a new problem presented itself. There was a growing stockpile of a variety of munitions containing red phosphorus taking up square footage in storage that could be used to house more modern munitions. At the time, there was no method or process in place to safely dispose of red phosphorus via open burning or open detonation. The composition acts similarly to white phosphorus, however a two molecule difference meant that a new process would have to be created.
"Previously, we had no capability of getting rid of red phosphorus," CAAA's demilitarization program manager Paul Allswede said. "We couldn't open burn it because of the negative environmental impacts, so there were developmental steps taken to address the shortfall for the Department of Defense. That was when the question of, 'Can you process it through the white phosphorus-to-phosphoric acid conversion plant' came about."
The Partnership
After the need was established, SciTech Services won the Department of Defense Ordnance Technology Consortium contract to develop an economical and environmentally friendly process that would convert the red phosphorous found in smoke grenades to phosphoric acid.
Specifically, they wanted to utilize an existing demilitarization capability, the white phosphorus-to-phosphoric acid conversion plant at Crane Army. SciTech Services then sub-contracted Gradient Technology to perform the design, fabrication, and integration of a prototype machine that had the ability to disassemble the smoke grenades and remove the material. Since 1999, Gradient Technology and Crane Army have worked together on several different demilitarization projects.
"The government required a demilitarization solution that would not only provide a demilitarization method for the red phosphorous grenade itself, but also liberate the material and package it in such a way that it could be fed into CAAA's white phosphorous-to-phosphoric acid facility," Gradient Technology Program Manager Joe Carroll said. "The entire initiative was based on the desire to have an environmentally safe process."
Unlike white phosphorus munitions that can be sliced open or have holes punched into the projectile to start the conversion process immediately, red phosphorus has an extremely low ignition point. This meant the extraction process of the red phosphorous from certain munitions containing red phosphorous would be much more difficult than that of munitions containing white phosphorous. Gradient Technology was able to develop a process that safely removes the red phosphorus from the round with the lowest probability of ignition.
Last year, a limited test was done which proved that the system was viable, and the process was put in place to begin demilitarizing L8A3 Smoke Grenades.
The Process
The L8A3 Smoke Grenade is an obscurant that, when used, generates a smoke screen to provide cover for the Soldier. It contains red phosphorous. Items containing red phosphorous require protocols to be in place in order to ensure the safe storage and handling of the munition because of the hazardous byproducts that red phosphorous can create.
"Red phosphorus outgasses phosphine, meaning that as the composition sits in storage it will throw off a gas," Allswede said. "When the composition is stored in the ammo cans there are gas-absorbing modules that absorb the phosphine, which is odorless, flammable and very hazardous. However, if the temperature of the ammo can gets too high the phosphine will out-produce what can be absorbed by the gas-absorbing modules."
While storage is an option for the grenade, a concentrated amount of phosphine can be very dangerous to those who deal with it in close proximity. It is flammable and toxic, which is why having a method to dispose of it in a timely manner in order to avoid storage is very important.
There are several steps involved in demilitarizing an L8A3 Smoke Grenade. An operator places the grenade into the modular unit created by Gradient Technology where the cylindrical rubber piece containing the composition is separated from the energetic. At this point, the energetic is taken out of the unit by the operator and it is taken to be demilitarized at another time in a different place by a different method.
The rubber piece containing the composition is then drilled to bore out the red phosphorous crumbles. The crumbles fall into a metal canister below, and the now empty rubber piece is scrubbed clean and becomes waste designated for a landfill.
"At this point, the red phosphorous is at its most vulnerable to start a smolder or fire," Allswede said. "When you work with red phosphorous, it's like drilling into a box of matchheads. The material by nature wants to burn and we're trying to drill through it without burning."
To safeguard operators in the event of a smolder, Gradient Technology designed the modular unit, within which the smoke grenade is disassembled and the red phosphorous is removed, with different levels of protection.
"The material, a quarter-inch inch thick steel plate, was selected to provide protection from the biggest threat of an ignition, the burster tube," Carroll said. "The walls of the modular unit are designed to withstand a detonation of the burster tube and properly mitigate the hazards involved, including fragmentation, thermal flux, and heat."
Aside from a detonation, another safety concern throughout the process is the outgassing of phosphine. In order to protect operators from the build-up of the gas, a ventilation system was put in place to ensure that the operator is not exposed to the hazardous gas.
"The ventilation system built in to the machine properly vents the air from inside the machine," Carroll said. "There are safety interlocks built into the computer logic that won't even allow the machine to operate unless the ventilation is sufficient."
Carroll also mentioned that in the event of an ignition or smolder of the material, the unit's ventilation system will contain and exhaust the smoke or gas generated by the burn and prevent the operator from being exposed to the harmful fumes.
There were isolated smolder incidents during the limited test run, so CAAA engineers designed and conducted an experiment to determine what needed to be done to reduce the risk of smoldering. To combat this issue, the process has two separate holding points that allow for the material to cool before it is packed onto a pallet with other canisters that are ready to be taken to the next step in the process.
"The cooler the material gets, the more stable it becomes," Allswede said.
Right after the crumbles fall into the metal canister, the canister sits in one spot for approximately eight minutes. After that, it is moved to another area to cool. Only then will an operator come to move the canister on to a pallet of other canisters that are ready to be transferred to the white phosphorous-to-phosphoric acid conversion plant to be demilitarized.
The Future
After this process takes place, the red phosphorous is treated like the white phosphorous. It goes to the same conversion plant and is converted into phosphoric acid that will eventually be used for fertilizer.
All around there are benefits to this type of closed demilitarization system. Not only is CAAA getting rid of a munition that can become hazardous as it begins to deteriorate, it is also generating revenue that will offset production costs which ultimately will save taxpayer dollars.
"Revenue is just the icing on the cake," Allswede said. "The real mission is reducing the stockpile of an unsafe, obsolete munition."
Gradient Technology also has the opportunity to further their industry's mission.
"This type of collaborative program execution allows the industry to utilize its expertise in engineering, equipment design and custom fabrication to support the government's mission while freeing up the government's resources to support the main mission, which is to support the Warfighter," Carroll said.
Growing the capability to demilitarize red phosphorous was not an easy task, but it was an important one for many reasons. Not only is this capability important for destroying an obsolete munition in a way that does not cause harm to the environment, it is also now a key element in ensuring the readiness of our nation's Warfighter.
"The ability to transition from white phosphorous to red phosphorous munitions demilitarization will provide a safe and environmentally friendly method for disposal of items with no other means of demilitarization," CAAA's Deputy to the Commander Norman Thomas said. "This process will not only provide a useable product for fertilizer manufacturers but will also free up 35,000 square feet of valuable storage space. This storage space will then be used to store more relevant munitions and improve readiness for today's Soldiers."
Currently, this effort is funded by the Product Director for Demilitarization and managed by the Joint Munitions Command Industrial Capabilities Directorate - Demilitarization Division.
The Red Phosphorous Demilitarization process is a Department of Defense Ordnance Technology Consortium contract to develop an economical and environmentally friendly process to download the red phosphorous from smoke grenades to further utilize an existing demilitarization capability, the white phosphorous-to-phosphoric acid conversion plant at CAAA, to convert the red phosphorous into phosphoric acid.
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