Steamboy - 28-1-2017 at 05:39
I am trying to isolate manganese, but my manganese fount is a mix of dimanganese trioxide (Mn2O3) and manganese dioxide (MnO2).
I want to transform the dimanganese trioxide fully to manganese dioxide, and next apply a reduction with aluminium or carbon:
3 MnO2 + 4 Al -> 2 Al2O3 + 3 Mn
MnO2 + C -> CO2 + Mn
What I can to do? Is there a more direct methode (that implies the use of usual materials) for transform the manganese oxide III and IV into elemental
manganese?
[Edited on 28-1-2017 by Steamboy]
unionised - 28-1-2017 at 05:57
I'm fairly sure that any oxide of manganese would be reduced by aluminium.
The potential problem is that the melting point of aluminium oxide is close to the boiling point of manganese.
Carbon would probably work but you need to be careful not to use too much or what you will get is manganese carbide.
Also, beware of the carbon monoxide produced in this sort of reaction.
Eddygp - 28-1-2017 at 11:14
Fortuately Mn(n+) will be easy to reduce with many things. C is possible, manganese carbide could be a problem (as unionised said), but
[http://pubs.acs.org/doi/pdf/10.1021/ja01227a028; Myers WR, Fishel WP. The preparation and hydrolysis of manganese carbide (Mn3C), J. Am. Chem.
Soc., 1945, 67 (11), pp.1962–1964] there are ways around it.
So, while...
"The observation of Ruff and Bormann [Ruff and Bormann, Z. Anorg. Chem., 88, 365 (1914)] that
carbon dissolves in manganese at temperatures
above its melting point to form an alloy corresponding
to Mn3C, was confirmed in this investigation." [Myers WR, Fishel WP., 1945]
...
"Its
water hydrolysis liberates all the combined carbon
as gaseous hydrocarbons chiefly methane, ethane,
and some alkenes of low molecular weight.
Acid hydrolysis promotes formation of free
carbon, hydrogen, and liquid hydrocarbons." [idem]
...to form Mn(OH)2 or equivalent, most certainly. These should probably be easy to separate from the crude product.
Steamboy - 29-1-2017 at 02:12
What are, typically, minimal temperatures required for start the reaction? Is it needed additions (like sulphur for sand thermite) for obtain an
efficient reaction and start such?
How I can obtain big chunks of manganese from the reaction (instead dust)?
How I can separate aluminium oxide from created manganese?
[Edited on 29-1-2017 by Steamboy]
DraconicAcid - 29-1-2017 at 19:16
Can you dissolve the original mixture of oxides in hydrochloric acid, possibly with some reducing agent present? If you have a solution of Mn++,
adding base and hydrogen peroxide should ppt MnO2. If peroxide isn't strong enough, hot chlorate solutions will oxidize it to MNO2, even if it's
acidic.
[Edited on 30-1-2017 by DraconicAcid]
The Plutonium Bunny - 9-3-2017 at 16:02
Not exactly how to change Mn (III) oxide to Mn (IV) oxide, but I just finished a good process for making elemental manganese metal from the black
"manganese dioxide" paste out of batteries. You could perhaps apply what I did to your situation.
Starting with the battery paste, I dried and ball milled it to make a fine powder. I washed this with water to remove soluble impurities and then
with vinegar to remove things like zinc oxide. The "manganese dioxide" paste actually has a ton of carbon in it, so I threw the paste into HCl which
I warmed with a hot water bath (outside). After all the manganese oxides in the battery paste finished dissolving, I filtered off the carbon to get
an iron-contaminated MnCl2 solution.
NurdRage has a great video (https://www.youtube.com/watch?v=BLJgBSrhZI8) on purifying manganese salts from batteries, and while he uses the sulfate, I repeated his process
for the chloride and it worked beautifully. It precipitates all the iron contamination as iron hydroxide and leaves the manganese in solution. With
my pure MnCl2 solution, I added NaOH to precipitate the hydroxide, which I then baked in the oven at 400°F to completely oxidize to Mn2O2 - one of
your oxides.
I mixed this with homemade ball-milled aluminum powder in a 2.93:1 Mn2O3:Al ratio and ignited it with a magnesium ribbon. Unlike my previous attempts
at Mn thermite with straight battery paste powder, this thermite reacted nicely and violently, as Mn thermites should. I got several cm-scale globs
of shiny manganese metal. This was using only batteries as a source of manganese.
I made a YouTube video on the subject, since it took so long to figure out and I know other people want to do the same thing: https://www.youtube.com/watch?v=BCmTzZa6ncY
You could also see pictures of the end result on my website: http://sciencewithscreens.blogspot.com/2017/03/experiment-65...
Perhaps you could use your manganese (III) oxide as-is for thermite? I don't know if you got stuff from batteries or elsewhere.
NitratedKittens - 11-3-2017 at 03:26
You have the same hot plate as me plutonium bunny