The inventor is Kevin Fleming, a retired Sandia National Laboratories engineer, and Sandia said it won't patent the fertilizer or license the formula so it can be freely available.
"One of Sandia's priorities is deploying the technologies that result from our research for the public good," said Pete Atherton, senior manager of industry partnerships at Sandia. "We think that making the fertilizer formula as accessible as possible is the best way to accomplish this mission."
Sandia said ammonium nitrate has an Achilles' heel from a terrorist's perspective. The ammonium ion is weakly attached to the nitrate ion but the right chemical reaction can easily pull them apart.
Fleming reasoned the ions could be separated by adding a compound they would rather cling to, called a metathesis reaction.
Fleming took iron sulfate and mixed it with ammonium nitrate. The result: 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, Sandia said.
Ammonium sulfate and iron nitrate cannot be detonated even when mixed with a fuel.
"It's a different compound," said Fleming. "At the chemical level it's a great fertilizer but does not detonate."
The formula was completed late last year and validation tests conducted.
"We were able to prove that there was little to no ammonium nitrate left in the resulting process," said Sandia chemical engineer Vicki Chavez. "It was very cool. We looked at pure ammonium nitrate and pure ammonium sulfate. The resulting sample looked more like ammonium sulfate."