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Mirage
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[*] posted on 6-2-2012 at 16:45
Making Antimony Metal


I have been wanting to make some Antimony metal for a while ever since I got some antimony trisulfide. I know that I would need a reducing agent to reduce the Antimony ion to its metal, but I have no idea what sort of reducing agent would work since Sb2S3 is only soluble in acidic conditions. Does anyone have any experience with this? Does anyone have any processes?

Thank you for any contributions

Mirage
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watson.fawkes
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[*] posted on 6-2-2012 at 19:01


Quote: Originally posted by Mirage  
Does anyone have any processes?
(1) Roast in open air to convert the sulfide to the oxide. (2) Smelt with carbon under a carbonate flux.

Disclaimer: Never done this myself.
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Mirage
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[*] posted on 6-2-2012 at 19:23


Okay, does anyone have any direct reduction reactions that would work? If not I'll try and figure out how to smelt it with the carbon.

Thanks for your idea!
Mirage
Quote: Originally posted by watson.fawkes  
Quote: Originally posted by Mirage  
Does anyone have any processes?
(1) Roast in open air to convert the sulfide to the oxide. (2) Smelt with carbon under a carbonate flux.

Disclaimer: Never done this myself.
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Mirage
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[*] posted on 6-2-2012 at 20:02


I beleive that I have made (impure) Antimony Metal. I roasted in a small beaker(wish I'd done it in a test tube) and after a minute, SO2 began to form. After a while, these fumes subsided, and none more was formed. I realized that I should have done this in test tube as it began to solidify on the beaker. As I began to try and chip it out, I found a crack forming on it, and decided the loss of a small beaker like this wasn't a big deal and broke it. I got a silvery gray metallic compound that resembles Antimony. Is antimony not reactive enough to oxidize in air and the sulfur just combined with air to form SO2? I've got some pics if you want.

Mirage

[Edited on 7-2-2012 by Mirage]
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watson.fawkes
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[*] posted on 7-2-2012 at 04:21


Quote: Originally posted by Mirage  
I beleive that I have made (impure) Antimony Metal. I roasted in a small beaker(wish I'd done it in a test tube) and after a minute, SO2 began to form. [...] Is antimony not reactive enough to oxidize in air and the sulfur just combined with air to form SO2?
It's possible you fired it in insufficient atmosphere and got a bit of metal still mixed with the sulfide. I can't tell from your description. Antimony is definitely reactive enough to oxidize, though. Antimony oxide is the major industrial product containing antimony; it's used as a fire retardant.

Ceramic crucibles are far more suitable for this work than any kind of glass. Small assay crucibles in the 30g capacity range sell for less than $5.
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[*] posted on 7-2-2012 at 06:36


Going by the reduction of SnO2 (tin and antimony are very similar) with carbon, reduction of antimony oxide with carbon will need at least red heat. Ceramic is indispensable.



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[*] posted on 7-2-2012 at 06:37


If you want to make antimony powder using a wet chemical process, dissolve the antimony trisulfide in concentrated hydrochloric acid. Hydrogen sulfide will be released and a solution of antimony trichloride will be formed. Place zinc granules in the solution. The zinc will vigorously dissolve, meanwhile precipitating antimony powder which is insoluble in hydrochloric acid. Of course, this gives a powder which is probably better for chemical reactions and alloying. Dry chemistry is the way to go for metallic-appearing antimony.

Antimony.JPG - 129kB




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Mirage
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[*] posted on 7-2-2012 at 10:26


Okay then maybe I should try and reduce the oxide I made with carbon in a little crucible. I will try the HCl/Zn method as well.

Thais for the information
Mirage
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[*] posted on 7-2-2012 at 21:32


So I tried the zinc/HCl method and it worked fantastically. I added a stoichiometric amount of Sb2S3 to some conc. HCl and heated slightly to help the reaction along. It produced some H2S (phew!) and it all reacted to form a clear less solution of SbCl3. I then added a stoichiometric amount of Zn metal. At this point, some H2 was evolved as the Sb precipitated out and Zinc Chloride was formed. I filtered, washed with several times and dried my sample of mostly pure Antimony metal.

Method works amazing, but it did not form large crystals as would the carbon reduction method would.

Mirage
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[*] posted on 7-2-2012 at 22:03


Quote: Originally posted by Mirage  
So I tried the zinc/HCl method and it worked fantastically. I added a stoichiometric amount of Sb2S3 to some conc. HCl and heated slightly to help the reaction along. It produced some H2S (phew!) and it all reacted to form a clear less solution of SbCl3. I then added a stoichiometric amount of Zn metal. At this point, some H2 was evolved as the Sb precipitated out and Zinc Chloride was formed. I filtered, washed with several times and dried my sample of mostly pure Antimony metal.

Method works amazing, but it did not form large crystals as would the carbon reduction method would.

Mirage


You can out it in a crucible and melt it to make it "metallic" looking.

High purity commercial polycrystalline material looks like this when slowly cooled blocks are broken open:



[Edited on 2-8-12 by UnintentionalChaos]




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[*] posted on 6-3-2012 at 06:11


Where did you get antimony trisulphide? Matches? :)
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[*] posted on 6-3-2012 at 07:01


It is not too hard to find stibnite, which is antimony trisulfide.



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Mirage
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[*] posted on 6-3-2012 at 09:15


Quote: Originally posted by Bhaskar  
Where did you get antimony trisulphide? Matches? :)



I have not seen any over the counter supplies. I ordered a small amount from HMS beagle. Check elemental scientific and united nuclear.
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[*] posted on 6-3-2012 at 11:26


Or something like this (http://www.amazon.com/Zs8809-Gemqz-Stibnite-Loose-Blade/dp/B...)



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[*] posted on 6-3-2012 at 11:35


Quote: Originally posted by Mirage  
So I tried the zinc/HCl method and it worked fantastically. I added a stoichiometric amount of Sb2S3 to some conc. HCl and heated slightly to help the reaction along. It produced some H2S (phew!)

Mirage


How sure are you that you didn't make the (very toxic) SbH3?
http://en.wikipedia.org/wiki/Stibine
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Mirage
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[*] posted on 6-3-2012 at 12:00


I don't think so. I wouldn't be surprised if SbH3 could be produced but from the reactions for it, I doubt any of this gas was made.

From wiki:
2 Sb2O3 + 3 LiAlH4 → 4 SbH3 + 1.5 Li2O + 1.5 Al2O3
4 SbCl3 + 3 NaBH4 → 4 SbH3 + 3 NaCl + 3 BCl3

A source of H- ions are necessary, but in HCl, the Hydrogen ion is positive.

Also, I very distinctly remember the smell of hydrogen sulfide, not anything else. I know on wiki it says they smell similar, but what I smelt, smelt a lot like H2S and only that.

Also, this reaction, from wiki again says that it is oxidized in air to antimonys oxide and water.

2 SbH3 + 3 O2 → Sb2O3 + 3 H2O

Another point against this is that it slowly decomposes at room temp, according to wiki again.

2 SbH3 → 3 H2 + 2 Sb

If I had saved some of the gas produced, then I might have been able to do a Marsh test, because Stibine, yields the same results as Arsine in the test.

All in all, I doubt I made any of this gas.


Mirage




Quote: Originally posted by unionised  
Quote: Originally posted by Mirage  
So I tried the zinc/HCl method and it worked fantastically. I added a stoichiometric amount of Sb2S3 to some conc. HCl and heated slightly to help the reaction along. It produced some H2S (phew!)

Mirage


How sure are you that you didn't make the (very toxic) SbH3?
http://en.wikipedia.org/wiki/Stibine
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[*] posted on 6-3-2012 at 13:41


The Marsh test, used to verify the presence of antimony or arsenic in a sample, uses zinc in acidic solution to reduce antimony salts to stibine, which produces a mark on a tile when the produced gas (consisting mainly of hydrogen) is burned under it.

The reaction you did used the same reactants (more or less) as the Marsh test. Therefore, it is likely you did produce a small amount of stibine gas, especially if there was a slight excess of acid.

Some useful info:
www.icdmetals.com/antimony-ingot.html

I suggest you do this next time under a fume hood or with a gas mask.

[Edited on 6-3-2012 by barley81]
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Mirage
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[*] posted on 6-3-2012 at 16:15


Yes, I did wear a gas mask and had a fan blowing all fumes outside. Also, if you did read my last post, then any stibine, would have reacted or decomposed.

Mirage



Quote: Originally posted by barley81  
The Marsh test, used to verify the presence of antimony or arsenic in a sample, uses zinc in acidic solution to reduce antimony salts to stibine, which produces a mark on a tile when the produced gas (consisting mainly of hydrogen) is burned under it.

The reaction you did used the same reactants (more or less) as the Marsh test. Therefore, it is likely you did produce a small amount of stibine gas, especially if there was a slight excess of acid.

Some useful info:
www.icdmetals.com/antimony-ingot.html

I suggest you do this next time under a fume hood or with a gas mask.

[Edited on 6-3-2012 by barley81]
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