A new fertilizer that fizzles in a homemade bomb instead of exploding could save lives around the world.
Evildoers have long known that common ammonium nitrate fertilizer can be easily transformed into a cheap and brutally effective explosive to be used in improvised weapons. Here’s a U.S. military test of a 300-pound fertilizer bomb using such a design:
The problem is that controlling a ubiquitous product such as ammonium nitrate fertilizer — which has such beneficial uses — is almost impossible, so the big brains at Sandia National Laboratories wisely moved in to end this abuse:
A Sandia engineer who trained U.S. soldiers to avoid improvised explosive devices (IEDs) has developed a fertilizer that helps plants grow but can’t detonate a bomb. It’s an alternative to ammonium nitrate, an agricultural staple that is also the raw ingredient in most of the IEDs in Afghanistan.
Ammonium nitrate fertilizer is illegal in Afghanistan but legal in neighboring Pakistan, where a quarter of the gross domestic product and half the workforce depend on agriculture. When mixed with a fuel such as diesel, ammonium nitrate is highly explosive. It was used in about 65 percent of the 16,300 homemade bombs in Afghanistan in 2012, according to government reports. There were 9,300 IED events in the country in 2009.
Ammonium nitrate explosives are not limited to Afghanistan. More than 700 IED attacks take place outside Afghanistan each month, and more than 17,000 global IED events have occurred in 123 countries in the past two years. The United States witnessed how deadly ammonium nitrate can be in the 1995 Oklahoma City bombing that killed 168 people.
U.S. efforts to curb the flow of ammonium nitrate fertilizer into Afghanistan through seizures, export controls and diplomacy have had limited success. The Joint Improvised Explosive Device Defeat Organization (JIEDDO) was established by the Department of Defense in 2006 to reach out to the armed services, private sector and academia for counter-IED technologies. JIEDDO last year issued a call for ideas on how to neutralize ammonium nitrate as an IED explosive.
Sandia optical engineer Kevin Fleming took on the challenge and developed a fertilizer formula as good as, if not better, than ammonium nitrate, but not detonable. “I looked at it differently,” said Fleming, who retired from the labs in February. “I’ve been an organic gardener since I was eight. We had five acres in Las Cruces with the problems of calcareous soils that are very similar to those in the Middle East. I know something about commercial farming.”
Okay, here’s where the heavy science drops hard:
From a terrorist’s perspective, ammonium nitrate has an Achilles heel. The ammonium ion is weakly attached to the nitrate ion. They hang onto each other, but the right chemical reaction can easily pull them apart. Fleming reasoned you could separate the ions by adding a compound they would rather cling to, called a metathesis reaction. “It would change into something else at the molecular level,” he said.
Fleming tried several materials including iron sulfate, a readily available compound that steel foundries throw away by the tons. When mixed with ammonium nitrate, the iron ion “grabs” the nitrate and the ammonium ion takes the sulfate ion. Iron sulfate becomes iron nitrate and ammonium nitrate becomes ammonium sulfate. This reaction occurs if someone tries to alter the fertilizer to make it detonable when mixed with a fuel.
“The ions would rather be with different partners,” Fleming said. “The iron looks at the ammonium nitrate and says, ‘Can I have your nitrate rather than my sulfate?’ and the ammonium nitrate says, ‘I like sulfate, so I’ll trade you.’”
Ammonium sulfate and iron nitrate are not detonable, even when mixed with a fuel, as is ammonium nitrate. “It’s a different compound,” said Fleming, who completed work on the formula in late 2012. “At the chemical level it’s a great fertilizer but does not detonate.”
Sandia chemical engineer Vicki Chavez ran a small-scale proof-of-concept of the reaction, and validated it. “We were able to prove that there was little to no ammonium nitrate left in the resulting process,” she said. “It was very cool. We looked at pure ammonium nitrate and pure ammonium sulfate. The resulting sample looked more like ammonium sulfate.”
Fleming said iron sulfate in fertilizer adds iron and acidifies soil. “It does good things for soil health. It takes alkaline soil and makes it more neutral, closer to an ideal pH level,” he said. “The closer you get a neutral pH, the more crops grow. Crop yield would improve significantly.
Awesome, right? But here’s the best part: Sandia could have patented the formula but opted to waive ownership rights for humanitarian reasons.
Images: Sandia National Laboratories, YouTube, Randy Montoya