3 replies to this topic

[mshaner]

Hopefully I won't get blasted for this question. I did a search and came up empty.

Yes, I know that lead media is best when surfaced with antimony, but that being said (and the fact that I'm making my own) can the balls just be coated or do they have to be melted down and homogenized with the antimony? Moreover, is it necessary to add tin to the picture? I'm hoping I don't have to melt these things down and just so you'll have some context - I'm milling down some Mg "chips".

Thanks,

Shane

[BigG]

You have to melt them down to create an Antimony Lead alloy. This will require some sort of a simple furnace. Tin is not a must although it makes alloying easier.

[Phoenix]

For milling metals, lead is IMHO, not the best choice really. If you've just got a fuel in your mill, the media needn't be non sparking. (Since the oxygen in the mill will be quickly consumed by the metal powder as it oxidises, a F/A explosion is not likely). Lead will get the job done eventually, but since Mg is harder than lead (and possibly hardened lead?) it won't be terribly efficient. I have tried with lead, and never got anywhere much, and the aluminium came out a nasty black/grey colour, which was lead, not aluminium carbide (so no, it wasn't dark Al). Steel will work much better. I have used bolts to mill aluminium, which worked quite well, and the Al came out shiny and silver. I have also used flint pebbles, which weren't quite as good, possibly as they were rounded not angular.

BTW, you probably already know this, but just in case; milling metals can be a rather hazardous procedure, as a pyrophoric powder can be produced. This means it will ignite spontaneously on contact with air. You can appreciate what happens when you open the jar and start screening out the media. Make sure you know what you are doing before attempting this. This problem and ways to avoid it were discussed a few weeks ago on rec.pyrotechnics, and probably have been many times before. Search throught the Google archive and read, if you haven't already.

[mshaner]

Thank you for all the insight. I've been contemplating this for about a month now. Frankly, my motivation is the fact that it drives me nuts know I have all these chips that I can't use in my propellants. Firefox ships them with the 325 mesh Mg. I spoke with Gary at Firefox just this week and his largest concern was with the moisture as I live in an area with high humidity.

To offset this, I'm going to load the barrel in the AC and will only mill the stuff 2-3 hours at a time and remotely, of course! I'm using a PVC barrel with a twist-in top and you know that is not airtight, if you will, so would it be better to open the top slowly or spin it right off? Also, I have no desire to take it down to a 325 mesh - just something useable.

Anymore thoughts

Shane