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Newsgroups: rec.pyrotechnics
From: (Arno Hahma)
Subject: Re: Homemade Al Dust Purity
Message-ID: <>
Date: Fri, 22 Apr 1994 05:41:18 GMT

In article <>,  <> wrote:

>yet... i can tell you it won't work! Magnesium easily oxidizes with water,
>and it would be totally useless. Magnulium (alloy 50% magnesium + 50%
>aluminum) isn't quite as bad, and might survive if you remove it fast enough,

If you plan to grind magnalium, such an abrasive method is not
necessary. Magnalium is very brittle and can be easily ground with a
mortar and pestle or better, a ball mill (that is how
magnalium is ground industrially).

If a ball mill is used, it is a good idea to fill it with nitrogen or
other inert gas before starting the mill. Note, that carbon dioxide is
not inert here nor are chlorinated solvent vapors. Hydrocarbon vapors
are inert in respect to magnesium.


Newsgroups: rec.pyrotechnics
From: John De Armond
Subject: Re: Am I magnesium?
Message-ID: <>
Date: Sat, 11 Jun 94 00:24:20 GMT (Jerry Ethridge) writes:

>machine a small cube or rectangle of exact dimensions and weigh it.
>This will give you the density and will tell you if you have pure
>Mg, Al, or an alloy. If you are sure that the alloy is just Al and Mg,
>then the percentages can be found by solving the simultaneous equations:

>density(Al) * Vol(al) + density(Mg) * Vol(Mg) = total mass

>Vol(Al) + Vol(Mg) = total Volume

>Solve for Vol(Al) and Vol(Mg).

>If you machine your volume of metal to high tolerances and use an
>accurate scale, you can get a very good indication of the
>percentages of both metals.

Or if you don't want to mess with machining a piece, you can measure
the volume of an arbitrary piece using the water displacement method.
Simply fill a container with water containing a little soap (to kill
the surface tension) right up to the brim.  Carefully place the object
in the water, being careful not to splash.  Arrange to collect the
overflowed water.  That amount of water has the same volume as the metal

Back to the subject, it is highly unlikely that a consumer-grade "mag"
wheel has any magnesium in it.  A reliable source for magnesium are
motorcycle engine sidecovers.  Many are made of almost pure magnesium and
the japs are nice enough to mold the word "magnesium" into the cover
somewhere.  A motorcycle junkyard is a good place to start.


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