crystal grower
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Bismuth oxide reduction
Hello,
I have been growing bismuth crystals a while ago and beside nice hopper crystals I also got some bismuth oxide from melting.
Is there a simplier way to reduce that oxide to elemental bismuth than reducing it with carbon under big temperatures without presence of oxygen?
Thakns for answer.
[Edited on 31-1-2016 by crystal grower]
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Texium
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You can dissolve the bismuth oxide in hydrochloric acid, and then reduce it with aluminum foil, yielding a fine black powder of bismuth metal. This
can then be dried and washed again with dilute HCl to remove excess aluminum, as bismuth will not dissolve in it.
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crystal grower
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Quote: Originally posted by zts16  | | You can dissolve the bismuth oxide in hydrochloric acid, and then reduce it with aluminum foil, yielding a fine black powder of bismuth metal. This
can then be dried and washed again with dilute HCl to remove excess aluminum, as bismuth will not dissolve in it. |
Thanks for answer, I will definitely try it .
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Tdep
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Expect to run into serious difficulty when trying to melt bismuth powder back into a lump. Despite it seeming easy because of the low melting point,
the powder has always oxidized before it melts for me.
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j_sum1
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| Quote: Originally posted by Tdep | | Expect to run into serious difficulty when trying to melt bismuth powder back into a lump. Despite it seeming easy because of the low melting point,
the powder has always oxidized before it melts for me. |
I guess you need either a suitable slag or an argon environment.
Suggestions for the former anyone?
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elementcollector1
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Sodium hydroxide worked when I was melting cadmium powder. The trick is to have a lot of metal powder and just enough flux to cover the surface, it
seems.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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blogfast25
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A low melting flux, like a soldering/brazing flux?
Teflon? MP = 327 C
[Edited on 1-2-2016 by blogfast25]
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blogfast25
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| Quote: Originally posted by elementcollector1 | | Sodium hydroxide worked when I was melting cadmium powder. The trick is to have a lot of metal powder and just enough flux to cover the surface, it
seems. |
Bismuth is amphoteric: chances are there will be reaction between molten Bi and molten NaOH.
Paraffin wax? BP > 370 C. Melt wax, add Bi powder until wax solidifies. Re-melt wax, add more Bi-powder util wax re-solidifies. Repeat until all
Bi-powder added and T > 280 C. Cool and find puddle of frozen Bi, neatly protected by paraffin. Live happy ever after. 
See: https://books.google.co.uk/books?id=kaa2qeFRXmUC&pg=PA62...
Stearic acid: BP = 361 C.
[Edited on 1-2-2016 by blogfast25]
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crystal grower
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Thanks everyone for answers.
I used to compress powders when I needed to melt them, but I will try to melt it with parafin as u said.
It seems to be simplier way.
[Edited on 1-2-2016 by crystal grower]
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Deathunter88
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| Quote: Originally posted by crystal grower | Hello,
I have been growing bismuth crystals a while ago and beside nice hopper crystals I also got some bismuth oxide from melting.
Is there a simplier way to reduce that oxide to elemental bismuth than reducing it with carbon under big temperatures without presence of oxygen?
Thakns for answer.
[Edited on 31-1-2016 by crystal grower] |
According to Nile Red you can simply heat the bismuth oxide and it will decompose into oxygen and bismuth metal.
See this video, at around 4 minutes 45 seconds.
https://www.youtube.com/watch?v=grpSfjUImUs
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crystal grower
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Of course but it must be in inert atmosphere as far as I know.
Or am I wrong ?
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AJKOER
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I would consider hydrogen gas atmosphere, which you may more inexpensively and easily generate.
[Edit] Downside, H2/air presents an explosion hazard.
[Edited on 1-2-2016 by AJKOER]
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bismuthate
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It seems unlikely to me that the two would react. What would you believe the reaction would yield?
Also any gas tank for welding or a stream of dry hydrogen should work for an atmosphere. Heck, even CO2 might work, but I'm not sure about that one.
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AJKOER
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Per Atomistry on Bi2O3 (link: http://bismuth.atomistry.com/bismuth_trioxide.html ) to quote:
"The trioxide does not decompose when heated to 1750° C. It is reduced, partially or completely, by a number of reducing agents, such as hydrogen,
carbon, carbon monoxide, silicon, sodium, potassium, methane, ammonia, ammonium chloride, potassium cyanide, aluminium carbide, and an alkaline
stannous solution. "
where the use of heated NH4Cl or an alkaline stannous solution seem interesting. Note, the result may just be a partial reduction to BiO.
If BiO is formed, to quote Atomistry on BiO:
"It is easily reduced to metal by heating on a charcoal block, or in a current of hydrogen or carbon monoxide; reduction in hydrogen takes place at
300° to 310° C., and in carbon monoxide begins at about 250° C."
Also:
"It is converted to metal by reaction with aqueous potassium hydroxide alone"
Link: http://bismuth.atomistry.com/bismuth_monoxide.html
[Edited on 1-2-2016 by AJKOER]
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