What Is in Road Flares? (spiegl.org)

by hyperific 33 comments 39 points
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33 comments

[−] jaggederest 30d ago
For extraction, you'd want to use different solvents that have different dissolving properties - usually something like water, ethanol, DCM, acetone, MEK, methanol, toluene or whatever.

For strontium, it looks like it's relatively soluble in short chain alcohols (methanol/ethanol) compared to the other two, so you'd crash out the potassium perchlorate by dissolving the mixture in water, then reducing the temperature to cause perchlorate to drop out of solution, then mix in a moderate amount of methanol to crash the potassium nitrate out, being left with a reasonably pure strontium nitrate, that you could then hot filter and recrystallize in anhydrous methanol if you wanted >90% purity. One or two rounds of recrystallization will leave you in the high nineties, probably above 97%.

This is a classic chemistry workup kind of problem and there are interesting engineering challenges embedded in it.

Of course... practical people just buy technical grade strontium nitrate and make fireworks out of it directly, as the article says.

[−] Athas 30d ago
This page reads like an exasperated response to constant discussions and requests for how to extract strontium nitrate from road flares, and emphasizes that it is hard and pointless in the first place. I never noticed such discussions, but maybe it's outside of my bubble! Quite an amusing read nonetheless.
[−] terribleperson 29d ago
That sounds like the kind of discussion that might show up on the venerable sciencemadness.org
[−] jimnotgym 30d ago

>Some older flare formulations also had things such as pitch, asphalt, wax, tallow, potassium chlorate and

black powder. Those are not likely to be part of modern flare formulations.

Most of the formulations in the table have charcoal, potassium nitrate or other oxidiser, and sulfur. Surely, to say they don't contain black powder is semantics, when they contain the ingredients of black powder?

[−] oasisbob 30d ago
You can look at pasta and bread the same way.

Potassium perchlorate and powdered aluminum can be used to make flash powder. Just because road flare contains both doesn't mean it's going to explode in your hand.

[−] ck2 30d ago
I don't know why this makes me think of it but the coolest "burning" thing has to be an "Oxygen Candle"

https://en.wikipedia.org/wiki/Chemical_oxygen_generator#Oxyg...

https://minearc.com/oxygen-candles-providing-emergency-air/

https://www.youtube.com/watch?v=g3Ud6mHdhlQ

Unfortunately they are "boring" in comparison, no flame/glow

[−] bookofjoe 30d ago
https://www.amazon.com/Visibility-Eco-Friendly-15-Minute-Saf...

>Specified and approved by the Bureau of Explosives and Underwriters Laboratories. No expiration date on road flares, the date shown on the flare is manufactured date. Orion flares will burn in all weather conditions, waxed Flare w/Plastic Cap. 15 Minute Burn Time — Non Perchlorate Formula

[−] NoSalt 30d ago
I've always wanted to activate a road flare. It looks so cool when they do it on TV and the movies.
[−] mikestew 30d ago
Amazon and your local auto parts store both sell them, they’re not expensive, so what’s holding you back? Just remember that they burn for 20 minutes or so, and you can’t extinguish them. (Well, a bucket of sand works.)
[−] gwbas1c 30d ago
So what happens when they are put into a bucket of water?

Answered my question: https://www.youtube.com/watch?v=SldmXuV3cLI

[−] mikestew 30d ago
There’s a reason that I specified sand in your bucket. :-)
[−] NoSalt 30d ago
To be honest, I would be slightly nervous about getting into trouble with the law.
[−] dylan604 30d ago
For what? What are you planning on doing with a lit road flare that would get you in trouble?
[−] NoSalt 30d ago
I thought it would be equivalent to calling in a "fake" emergency, or abusing the 911 system, or something like that.
[−] fergie 30d ago
I'm missing some context here: Why do we want to extract strontium nitrate anyway?
[−] brazzy 30d ago
Um... some context? What even are road flares? And why would I want to extract strontium nitrate from them?