Explosives go unleaded

Explosives could become safer following the synthesis of lead-free environmentally-friendly primary explosives, by US researchers.

Primary explosives are used to detonate more powerful, but also more stable, secondary explosives, such as dynamite and TNT. For the past 100 years, the lead-based compounds lead azide and lead styphate have been the most widely used primary explosives. 

But lead poses toxicity concerns. A 1991 study showed that employees at an FBI shooting range had lead contamination levels 10 times higher than US government limits. Candidates for more environmentally-friendly primary explosives have so far been too unstable or contained other toxic compounds. 

By studying previously developed explosive compounds, researchers led by Thomas Meyer from the University of North Carolina, Chapel Hill, based their primary explosive around a non-toxic compound that was highly energetic and rich in oxygen and nitrogen. They found that 5-nitrotetrazolato-N² (NT) possessed just these properties, and created four primary explosive compounds by combining NT with various metal ions, including Na⁺, Fe²⁺ and Cu²⁺.

Meyer and his colleagues tested these compounds and discovered that they were actually better primary explosives than lead azide and lead styphate, being more stable but just as effective at triggering large explosions. 

Jon Evans