| Pages:
1
2 |
Sulaiman
International Hazard
Posts: 3938
Registered: 8-2-2015
Member Is Offline
|
|
As I still have a few kg of lead and its oxides I occasionally think about carbothermal reduction;
1: Oxygen must not contact molten lead - because it will oxidise the lead.
2: The hot lead oxides are reduced by carbon monoxide
3: The hot carbon needs oxygen to produce carbon monoxide
#1 and #3 indicate (to me) that the carbon should (mostly) not be mixed with the lead oxides
I have negligible fabrication skills or facilities,
just the beginning of an idea that may work that is not too complex,
something equivalent to a chimney, with burnable stuff in the bottom and lead oxides waste on top,
controlling the oxygen/air flow to ensure incomplete combustion,
but enough combustion for the required heat.
the carbon oxides produced should fill the chimney and exclude oxygen from above
any unoxidised lead, or oxides reduced to lead,
should drip to the bottom for further processing once cool.
for outdoor/remote use, for fuel some combination of charcoal, coal, wood, twigs, paper, old oil, solvents and paint are candidates.
or in a workshop, a vertical pipe from a furnace for heat, with charcoal and an air feed in the bottom
etc.
I'd love it if someone tries similar (and tells us how it went)
I may try myself eventually - any suggestions, ideas, pointless warnings etc.?
CAUTION : Hobby Chemist, not Professional or even Amateur
|
|
|
RU_KLO
Hazard to Others
Posts: 318
Registered: 12-10-2022
Location: Argentina
Member Is Offline
|
|
Maybe it would be "easier" to do a Vacuum Carbothermal Reduction.
WARNING: do not attempt in you dont know the dangers. Explosion risk. Lead risk. Contamination risks.
found this:
"Extraction of Lead and Zinc from Zinc Leaching Residue by Vacuum Carbothermal Reduction"
https://link.springer.com/article/10.1007/s40831-025-01341-7
Could not dowload the DOI.
The vacuum carbothermal reduction-volatilization method was used to extract Pb and Zn from zinc leaching residue
The results indicate that under the conditions of a furnace pressure of 10 Pa, a carbon content of 18.5%, and holding the pellets at 1000 °C for 30
min, the volatilization rates of Pb and Zn from the zinc leaching residue reach 98.93% and 95.40%, respectively.
Dont know if these conditions are difficult for amateur laboratory.
1000 °C for 30 min maybe not, but 10Pa seems a lot (roughly equivalent to about 0.075 Torr or 0.000075 Bar)
From what I read, only possible with scientific equipement.
(A high-quality, two-stage vacuum pump for air conditioning systems can typically lower the pressure to between 200 and 500 microns (0.2 to 0.5 Torr)
which is way higher than 0.075 Torr needed.
Also a condenser capable of vacuum pressure and heat needs to be used.
So..... maybe not.
(Or more heat less vacuum?)
Go SAFE, because stupidity and bad Luck exist.
|
|
|
pesco
Hazard to Self
Posts: 95
Registered: 19-11-2015
Member Is Offline
Mood: No Mood
|
|
If the goal is the use of gaseous CO as achievement then fair enough. However if the goal is to just reduce oxides to metal, then using gaseous CO is
like going from US to Canada via Mexico 
When I was a kid we used to go to the train station and collect heaps of used wagon seals. Just a short stroll along the railway and bucket was full
and too heavy to lift
Occasional lead-acid battery happened as well.
With all these lead we were casting all sorts of things, from fishing sinkers through medals and toy figures and to working mini cannons. Black powder
for cannons was another adventure to us
To reduce oxides you need some carbon source. It can be saw dust, grain, grass clippings, charcoal, coke (the black chunks, the white powder would be
too expensive ) etc.
Then you need a generous amount of flux. Borax is great, but sodium (bi)carbonate is just as good and much cheaper. As a matter of fact, when your
source is old lead-acid battery then carbonate is a must. In the melt it reacts with lead sulfate in double displacement reaction. The resulting
sodium sulfate adds to the flux and lead carbonate decomposes to oxides which in turn are reduced by carbon to metallic lead.
Flux is important for number of reasons - prevents formation of new oxides cutting the metal off of air, separates metal from slag and makes the slag
easier to deal with.
Paraffin is also great flux, especially just before the pour. Somehow it makes the pour go smoother. Possibly oil would do the same what paraffin
does, but I never used oil. At least I don't remember. I guess it might smoke a bit more.
I use to melt lead in any old steel pot on a small bonfire or wood stove. I doubt the temperature ever exceeded 500 °C. Hotter should be fine and
probably even better, but it is not necessary.
During melting it is good to stir content of a "crucible" with a wooden stick. Wood serves as additional reducing agent and stirring helps to separate
the slag.
Using any solid carbon source is actually carbothermic reduction. The carbon is reducing oxides tuning into CO2 directly or in stages via
CO.
If a 9-13 year old kids were doing it routinely then it can not be that complicated
[Edited on 24-1-2026 by pesco]
|
|
|
| Pages:
1
2 |
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
