If you ever see a large industrial metal fire (yes, they happen) on the news, you may be surprised at what the firefighters do to extinguish it: nothing. Several metals, including lithium, sodium and magnesium, can burn easily, and from time to time large amounts catch fire in factories. But even heaps of burning metal need not cause immediate panic. They don’t blow up; instead they tend to build up ash that chokes off their oxygen supply, so they slowly burn out.
In fact, magnesium reacts so well with CO2 that it will burn inside –109°F dry ice (the solid form of carbon dioxide). This jack-o’-lantern was made by lighting a handful of magnesium shavings stuffed into a hole carved in the back of a block of dry ice. It burned crazy bright for about a minute.
Water and foam are even worse on metal fires. If the metal is molten, the resulting steam explosion tends to fling it everywhere. What’s more, some hot metals can split water into oxygen and hydrogen, creating the likelihood of a major hydrogen gas explosion.
Next time there’s a sodium fire, the firefighters plan to do one simple thing: walk away. Metal fires are just too hot to handle.
ACHTUNG! Don’t try this at home. Burning metals are dangerous and unpredictable. Ordinary fire extinguishers can spread the fire or cause explosions.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.