Seven years ago I tried to make Na and K metal by heating their carbonates with powdered charcoal to 1200 C in a steel retort. As the vapors which
appeared, there was indeed alkali metal formed, but it burned again, so the proof of concept succeeded.
But now I have ordered Ar gas to flush the retort, make a stainless steel retort and moderate the heat with a sandbox to get a more even heat
distribution over the bottom of the retort to prevent overheating. In earlier experiments, the (mild steel) retort melted locally at the bottom due to
overheating and moreover, the alkali metal burned due to traces of air.
Here a sketch how I want to make the retort. Does somebody have better ideas ?
Sedit - 29-8-2017 at 12:25
What exactly is the reaction that is taking place? Wouldn't CO2 form somewhere and react with the Sodium?Metacelsus - 29-8-2017 at 16:40
Indeed for the challenge, but in this way the K is distilled. This used to be a commercial process in the late 1800s. I tried electrolysis but that is
a far more tedious process. I will flush the retort with Ar gas before running.SWIM - 8-9-2017 at 09:51
I read about old potassium making processes some time ago, and I think I recall there being, for that process, some black byproduct that would build
up in the condenser(nose of the retort?) which was a potential hazard(explosive?).
I may be confusing two processes here, or just be plain wrong. I'll see if I can find the description I read.
This was some old source material, so they obviously weren't doing the process under an argon atmosphere.
I think they were condensing it into 'rock oil', or into flat containers of some sort immersed in 'rock oil'.
And It's possible it was just some byproduct that clogged the nose of the retort and wasn't hazardous in and of itself.
Will post again if I find anything more definite than my hazy memories..
@halogen,
thanks for filling in the blanks, because I couldn't find that old reference, but had an uneasy feeling about it.
[Edited on 9-9-2017 by SWIM]halogen - 9-9-2017 at 06:13
The hazard of the process was indeed that black byproduct. Possibly only potassium intercalcated graphite, possibly funnier things. Research, in
modern times, on the reduction of carbon monoxide by alkali metals in solution reveals such products as acetylenediolate, and deltate. The intimate
mixture necessary for reasonable yields of potassium was ensured by the combustion of tartrate salt, a byproduct of vinous fermentation. Other carbon
bearing salts worked.
symboom - 9-9-2017 at 09:35
Mermaidkiller is metalresearcher on here :O working on challenging projects
Potassium bitartrate is cream of tarter in stores
Kind of expensive given the amount
The black deposits sounds like pyrophoric potassium graphite
Or potassium carbide both doesnt seem possible in the condensing phase more likely finally divided potassium metalmetalresearcher - 19-9-2017 at 12:29
I tried it a few times, but I probably added too much charcoal.
I heated it 10-20 minutes to 1200 C in a small propane furnace in a steel retort flushed by Ar gas.
I used powdered charcoal.
After running the test (a few grams, 4:1 weight ratio K2CO3 / C, which is well excess of C to prevent oxidizing) and opened the retort after allowing
it to cool, some black crud appeared which caught fire in air but not with the familiar magenta K color, but just a 'fire' solor.
Dumping it in water resulted in CaC2 like reactions with bright very sooting flames.
Is this K2C2 ?
So next run will be ratio 6:1 which is stoichiometrical.
