I have some Li metal and found a Youtube video of a guy distilling K from KCl + Li metal.
I repeated this and made a steel tube retort with a copper tube attached to it ending in a beaker with lamp oil. I have no pure KCl, but diet salt
(2/3 KCl and 1/3 NaCl). I heated the retort to about 800 C, I checked temperature with an infrared pyrometer pointed at the red hot retort and avoided
getting it hotter than 850 C to prevent too much Na (bp 889 C) evaporation. K boils at 768 C, and so I hoped that the not too high temperature gives
priority to K vaporizing over Na, but still too much Na distilled over.
After ten minutes beads of shiny metal appeared and after 20 minutes I shut it down.
The beads coalesced to a single one of 15mm across and after cooling down to room temp. it is still liquid, so it must be NaK.
I threw a small bead into water and it was bright yellow, so Na dominates.
EDIT: But why is there still so much Na ? I know (see Cody's Lab) that with Na one can free K from KCl, so when I have a *mixture* of two parts KCl
and one part NaCl, then K has priority over Na due to its lower boiling point (and thus higher vapor pressure ai 800 C ) ?
[Edited on 2020-6-29 by metalresearcher]Ubya - 29-6-2020 at 12:25
well you already have a direct source for NaK
maybe you could try a few recrystallizations to get a higher concentration of potassium chloride (iirc potassium chloride shoul be less soluble in
methanol)B(a)P - 29-6-2020 at 12:26
Nicely done and thanks for the write up. Could you please include a picture of two of you retort?metalresearcher - 29-6-2020 at 21:47
As requested, here pictures of my retort.
It is a 3/4" 3mm thick steel pipe, 80mm long, squeezed together and welded and the other end welded to a 3/8 steel knee which is screwed to a brass
3/8 => 15mm copper tube adapter. The copper pipe of 25cm long ends in the beaker with oil. To refill it, I unscrew the brass adapter.
BTW, I have lots of KBr, will that also work with Li ?
[Edited on 2020-6-30 by metalresearcher]Belowzero - 29-6-2020 at 22:00
Nice experiment !
KCl can be cheaply obtained from fertilizers.
Might be a better source than diet salt
Did you measure the yield?
[Edited on 30-6-2020 by Belowzero]metalresearcher - 30-6-2020 at 09:17
KCl can be cheaply obtained from fertilizers.
Might be a better source than diet salt
Did you measure the yield?
Still low, about 2g NaK from 20g NaCl/KCl 1:2 mix and 2g Li metal.
But I prepared for the next step. As I don't have KCl, but do have K2CO3, I dissolved 20g K2CO3 in 100ml 10% HCl solution until sizzling stopped. Then
I evaporated the water and dried it thoroughly it resulted in 21g KCl. Together with 2g Li this should yield a few grams of K.
KCl + Li => LiCl + K
75.5 7 42.5 40 (molecular weights) metalresearcher - 1-7-2020 at 10:53
And now I got potassium in nice silvery beads !
I used KCl obtained from K2CO3 dissolved in HCl solution which I dried out. I used 20g of KCl and 1.9g Li metal, heated to 750 - 800ºC in a steel
retort and the distilling ending in a beaker with lamp oil.
But still it contains some Na due to some yellow tinge in the flame. I don't know where from.
