8 replies to this topic

[Gary]

Hi,

I have a block of high-purity magnesium metal, from which I wish to obtain a fine magnesium powder for use in magnesium stars, fountains, etc.
I'm not too keen on ball-milling, because of the pyrophoric nature of the fine powder obtained by this method.
Are there any viable alternative methods for producing a fine magnesium powder from a solid block of magnesium metal?
Magnesium powder seems very hard to come by, which is why I have resorted to producing my own Mg powder from a solid block of Mg.

Cheers,

Gary

[Asteroid]

I didn't think magnesium was pyrophoric to the same extent as aluminium, but i may well be wrong. Using a ball mill, if you open it on a regular basis, pyrophoria is not much of a hazard.
Otherwise try this method.
Also while going looking for the metal grinder I found this PDF on handling pyrophoric reagents which might interest you.

[EnigmaticBiker]

I've used a different method mentioned here, using oil to overcome the pyrophoric reaction problem.

http://www.pyrosocie.......=260&st=420

[Gary]

I have a possible solution:
1. Produce magnesium turnings or coarse granules, using a file or sander.
2. Coat these in oil prior to placing them in the ball-mill. Also, coat the media and the inner surface of the mill with oil.
3. Ball-mill using the hardest media, until a very fine powder is produced. Hopefully, the oil should exclude oxygen from the Mg and thus prevent an exothermic pyrophoric reaction.
4. Add the oil-coated Mg powder to a detergent solution to remove the oil. Dissolve some potassium dichromate to slow the reaction between Mg and water.
5. Filter the magnesium under suction (use a Buchner apparatus, with a hand -operated vacuum pump).
6. Wash with more detergent solution to remove traces of oil.
7. Now wash with warm water to remove traces of detergent.
8. Treat the Mg with a solution of potassium dichromate to protect it from atmospheric oxygen.
9. Filter and allow the Mg powder to dry.

I have a possible solution:
1. Produce magnesium turnings or coarse granules, using a file or sander.
2. Coat these in oil prior to placing them in the ball-mill. Also, coat the media and the inner surface of the mill with oil.
3. Ball-mill using the hardest media, until a very fine powder is produced. Hopefully, the oil should exclude oxygen from the Mg and thus prevent an exothermic pyrophoric reaction.
4. Add the oil-coated Mg powder to a detergent solution to remove the oil. Dissolve some potassium dichromate to slow the reaction between Mg and water.
5. Filter the magnesium under suction (use a Buchner apparatus, with a hand -operated vacuum pump).
6. Wash with more detergent solution to remove traces of oil.
7. Now wash with warm water to remove traces of detergent.
8. Treat the Mg with a solution of potassium dichromate to protect it from atmospheric oxygen.
9. Filter and allow the Mg powder to dry.

PS: use potassium dichromate (sold as chrome mordant) with caution- it is toxic and carcinogenic.

[BigBang]

Hi,

I have a block of high-purity magnesium metal, from which I wish to obtain a fine magnesium powder for use in magnesium stars, fountains, etc.
I'm not too keen on ball-milling, because of the pyrophoric nature of the fine powder obtained by this method.
Are there any viable alternative methods for producing a fine magnesium powder from a solid block of magnesium metal?
Magnesium powder seems very hard to come by, which is why I have resorted to producing my own Mg powder from a solid block of Mg.

Cheers,

Gary

A lot of trouble to go to, to get Mg powder! Actually Mg powder is not that difficult to find. There are several places where it can be bought, most of which are mentioned on this forum. Also its not that expensive.

[Gary]

A lot of trouble to go to, to get Mg powder! Actually Mg powder is not that difficult to find. There are several places where it can be bought, most of which are mentioned on this forum. Also its not that expensive.

I have tried various websites for Mg powder, but to no avail. I got no reply from Active Metals.
Another website told me that they would sell me magnesium provided I could demonstrate knowledge of how to extinguish a Mg fire (well, do'nt use water or CO2) and produce documentation to prove that the fire brigade are aware of my hobby! I am only after about 500g to 1kg of the stuff, not hundreds of kilograms!
Would you be willing to divulge your source?

[starseeker]

I have tried various websites for Mg powder, but to no avail. I got no reply from Active Metals.
Another website told me that they would sell me magnesium provided I could demonstrate knowledge of how to extinguish a Mg fire (well, do'nt use water or CO2) and produce documentation to prove that the fire brigade are aware of my hobby! I am only after about 500g to 1kg of the stuff, not hundreds of kilograms!
Would you be willing to divulge your source?

Hi Gary,
try www.hobbychem.co.uk,i think they sell Mg powder,i have used them a few times and very quick delivery etc,
regards,
vince.

[BigBang]

Hi Gary,
try www.hobbychem.co.uk,i think they sell Mg powder,i have used them a few times and very quick delivery etc,
regards,
vince.

1kg of Mg powder, thats a lot! If you want that amount, hobbychem is not the place to go, they are very expensive, (i dont think they sell Mg powder anyway)

For larger amounts Keten is going to work out much cheaper. The only problem with them is that its a bit hit and miss whether you get your stuff. He used to be very unreliable, but he has improved recently.

Edited by BigBang, 13 February 2007 - 11:36 PM.

[BrightStar]

Another website told me that they would sell me magnesium provided I could demonstrate knowledge of how to extinguish a Mg fire (well, do'nt use water or CO2) and produce documentation to prove that the fire brigade are aware of my hobby! I am only after about 500g to 1kg of the stuff, not hundreds of kilograms!

Ummm... 1kg of Mg powder would easily burn your workshop to the ground. Your potential suppliers do have a point here. How would you extinguish it?

Suppliers for small quantites of fine atomised and various other grades of Mg do pop up on Ebay from time to time. The quality can be variable though - some of it is quite oxidised but is still usable for illuminants etc.

Edited by BrightStar, 14 February 2007 - 12:08 AM.