Sciencemadness Discussion Board

Lead-acid battery lead capture

wvcruffler - 13-10-2025 at 11:44

howdy all,

I need some pure lead for casting roundballs for my flintlock and I have some old batteries around the farm here. I watched a few videos on what all is inside these batteries and it appears that there is
1. Some sulfuric acid - which can be to some extent reclaimed
2. Lead metal in frames
3. Lead dioxide and lead oxides that make up quite a bit of the electrodes
4. Probably some other structual stuff. Can't tell.
I have a furnace that can melt lead (and brass and probably silver...)
My plans - Stuff chunks of the stuff into my 8kg crucible to melt off the lead frames and pour it into ingots and put the lead oxide (probably mostly oxide now since the dioxide would probably decompose from the heating).
Once that lead is off crush up the lead oxide and mix with an excess of something that will burn to reduce the lead oxide at combustion temps to lead metal and carbon dioxide. thinking crushed up Kingsford charcoal (BIL works ar Kingsford so I get it for free). Be a lot of dross on top of the somewhat smaller amt of lead produced but I think it will make some pure-ish lead and then pour the rest of that off. No clue what will be in that dross but it will probably go into the "going to hazardous waste place" bucket.
Any thoughts? Better ways to do this? If there is some red lead ill try to wash that and put aside as a reagent for later but I wont need THAT much of it ever. Anyway, won't be until next week Ended up working 19 of 21 days in a row 12 hour shifts so tied up here instead of on the farm playing.
Cheers
DrPhil

Radiums Lab - 13-10-2025 at 14:18

Impure Lead fumes a lot when melting so have a respirator around.

wvcruffler - 13-10-2025 at 15:07

Quote: Originally posted by Radiums Lab  
Impure Lead fumes a lot when melting so have a respirator around.

Indeed! Most of my lead is from wheel weights and they not only have impurities but hydrocarbons all over them,. I have a resiprator.

Hexabromobenzene - 13-10-2025 at 21:25

See my topic
https://www.sciencemadness.org/whisper/viewthread.php?tid=16...

violet sin - 14-10-2025 at 08:29

After seeing a number of vids with people only getting ~3# of lead while breathing fumes .. I was convinced there was a better way.

I was considering using an acid to capture the oxides as soluble salts, and then cementing it out like copper onto iron etc. soluble lead salts sound less than fun and landlords might feel ways about things if it should be discovered. So curiosity was beat out by practicality so far. Seems like high strength acetic acid can be found relatively cheaply these days, ~30% /20$ gallon. Just seems like whatever you did, recovering the acid would be wise, and an exit strategy needs to be in place.

So don't rush I to a foolish situation with lead, think carefully before playing. Best of luck

wvcruffler - 14-10-2025 at 09:09

I am fortunate that I live on 100 acres and have plenty of space to do projects indoors or out (I have a few large barns).

I do wonder if when I pack the crucible in the furnace - should I cover it or leave it uncovered? I suspect its going to reduce the lead oxide either way, but perhaps covered the lead metal will have less oxygen available to be oxidized itself. I may do some with and some without and see if there is a difference in % recovery. Probably have to dry the samples in my heat treat oven so that moisture doesn't throw off my results!

DrPhil

MrDoctor - 14-10-2025 at 16:17

i recently got a nice fancy benchtop furnace and had been wondering about this also.
when you take lead acid battery plates and melt them down, you wind up with a lot of slag from the lead made from lead dioxide and sulfate, and/or their decomposition products by the time they float to the surface of the melt.
youll also have the fumes from arsenic i believe, oxides of calcium if its a calcium reinforced battery, and any other misc alloying agents, for which lead is usually the least reactive, so, they should pretty much end up as oxides once molten, prefferentially forming an oxide as oxygen reacts with the surface of the melt.
if the battery is not originally yours, and you sourced some really big, expensive, serviceable long life batteries, theres a chance theres also going to be cadmium salts present due to the use of battery conditioner. in the slag, this is now cadmium oxide/sulfate, i would presume.

melting down the lead for collection is easy, but i think its important to do something with the slag as well, its pretty much still over 95% lead compounds, if you can get just most of it out, whatever is left is easily dealt with, nuclear style, in an old jar or something you keep for the rest of your life slowly filling it up with incredibly toxic heavy metal waste products ;)

PbO2 decomposes progressively into different oxides before finishing as PbO at around 600C, PbO can be turned into salts moderately easily i think, and from there theres ways to do seperation. Without doing more research, i would want to take the slag, make sure it had been roasted, tbh it would be better to just remove it right away and then heat in a crucible independently after the main mass had been molten and cast, then re-melt the collective slag to recover all the metal in a small crucible overheated to ensure PbO2 decomposition now that its relatively easy. then, removing the lead metal, i would ultrasonicate the slag in the desired acid, lets say, acetic. after a while, without filtering, i would perform electrolysis on this, or id like to anyway, but this is where things get complicated and i dont quite understand the chemistry.

theres 2 routes here, one is to use an inert anode such as graphite, and just plate everything out, lead should come out first if its the least reactive element present, though lead plates out both on the anode and cathode under certain conditions, which i dont quite understand. its the sort of thing where using a membrane might be good, but if its porous as many are, its going to get absolutely caked in lead.
the other route is to instead use anode made of a sacrificial reducing agent, such as aluminum. But i dont know how that will play in this reaction since it will want to instantly displace lead on its surface, but then that will anodically oxidize and form PbO2 and, basically i dont understand the equillibrium that is established.
In my head though i think that lead plated and oxidized at the anode would be just as likely to be dissolved again by the acid, plus the lead that forms on the anode, is also just plainly a good anode material that might extend the useability of the aluminum. And as long as the potential is managed, lead shouldnt get oxidized out of solution in a form that cannot return.

this would be pretty straightforward to do and observe, but, i have no desire to put in the decontamination efforts in for this sort of experiment, because its just an experimental, simple process for minimizing lead waste without much handling, at its core it amounts to just a slag teabag in a simple electroplating setup to minimize the volume of the slag. Unlike purely just cooking the slag and dissolving in acid, and working with the salts, electroplating, especially after roasting and ultrasonication, should allow the recovery of the bulk sulfate too without having to add alkali hydroxides to the mix to de-sulfate the slag, although maybe it wouldnt be so bad to include some lime during either phase, since calcium oxide/sulfate is probably going to be present either way.



lastly, while i dont endorse it, for obvious safety reasons, i do wonder if a controlled thermo-reduction could not be done at lower temps using molten aluminum and/or carbon. The problem there is obviously that lead thermite is bad, plus once molten, aluminum would seperate pretty strongly away from the oxides preventing further reduction, and mixing intimately as a powder to avoid this would lead to it all reacting at once quite exothermically, making a big toxic mess that will lower the IQ of children in the neighborhood for generations to come.
once cooked so the only lead oxides remaining are PbO, and also sulfate as a substantial constituent of the slag, i just wonder if aluminum has enough reducing power as a molten blob to reduce all the surrounding oxide/sulfate without requiring much mixing. And if it would be able to occur at temperatures well below the reaction temperatures normally needed for reduction, 600C can be maintained with a bunsen burner and a well insulated crucible, over 1000C, things get complicated and it also stops being economical compared to disposal fees.



Hexabromobenzene - 15-10-2025 at 03:34


Electrolysis, as in my topic, is the best option. You can try pyrochemistry. But you need heating up to 1000. Here is the video: https://youtu.be/UoXRDmS-QIw

According to the video, it was an old Soviet battery from a truck or other large equipment dug out of the ground. To decompose sulfate used sodium bicarbonate and hydroxide were used as a flux, charcoal as a reducing agent
Author according to comments used anthracite coal and firewood. In this case, the lead condensed on the chimney and the author put on a gas mask. Do you need this?
Electrolysis will also give you a solution of sulfuric acid

I also don’t understand the problems with lead disposal. Where I live they pay for a lead battery, but you don’t. Small batteries usually thrown into regular trash because its are not accepted.


[Edited on 15-10-2025 by Hexabromobenzene]

wvcruffler - 15-10-2025 at 10:10

I may try both electrolysis and reduction.

I don't know why it would need to be 1000C - there are videos of small scale reduction of lead oxide using a bunsen burner. Perhaps its the conversion of lead sulfate to lead oxide then reduction of lead oxide to lead metal that requires that temp? There should not be a large amount of lead sulfate in these car batteries. There will be some, but should mainly be lead dioxode and lead oxides. Now I HAVE to do this!!! I believe I will need to have the crucible closed for the lead reduction. Wish I didn't have to work this week - the weather is going to be perfect for such hijinks.

For Electrolysis
What did you use as electrodes? Did you attach your copper wire to the lead frames?
Looks like the anode and cathode are continuous with the big pile of frames and oxide. Haven't seen it done that way before. Assuming you filter and melt the soft lead after completion. What about using the oxide to make a lead salt (like lead acetateor lead nitrate) then electolysis. I'm going to be making some lead nitrate for a later experiment involving Lead Hypophosphite :D

Anyway, this is going to be a fun one. Then casting the lead into roundballs and shooting them with home made propellant will be the capper.



MrDoctor - 15-10-2025 at 14:30

Quote: Originally posted by wvcruffler  
I may try both electrolysis and reduction.

I don't know why it would need to be 1000C - there are videos of small scale reduction of lead oxide using a bunsen burner. Perhaps its the conversion of lead sulfate to lead oxide then reduction of lead oxide to lead metal that requires that temp? There should not be a large amount of lead sulfate in these car batteries. There will be some, but should mainly be lead dioxode and lead oxides. Now I HAVE to do this!!! I believe I will need to have the crucible closed for the lead reduction. Wish I didn't have to work this week - the weather is going to be perfect for such hijinks.

For Electrolysis
What did you use as electrodes? Did you attach your copper wire to the lead frames?
Looks like the anode and cathode are continuous with the big pile of frames and oxide. Haven't seen it done that way before. Assuming you filter and melt the soft lead after completion. What about using the oxide to make a lead salt (like lead acetateor lead nitrate) then electolysis. I'm going to be making some lead nitrate for a later experiment involving Lead Hypophosphite :D

Anyway, this is going to be a fun one. Then casting the lead into roundballs and shooting them with home made propellant will be the capper.





lead sulfate is pretty much exclusively what fouls up the surface of the batteries and renders it inoperable, aside from sectors disintegrating away. PbO2 is nice and conductive and doesnt interfere. when the sulfate forms crystals that are too big to redissolve upon charging, in a single standard cycle, that leads to the formation of more sulfate one way or another, either consuming all the acid, or just changing the characteristics of each cell making them unbalanced causing surface oxide to erode or dissolve.
but you should expect a lot of sulfate from a battery that holds charge/discharges poorly, also the same goes if its just dead flat, then it will be coated in the healthy reversible lead sulfate too which is chemically no different from the big problematic crystals.

But lead sulfate will eventually all leech out via slow electrolysis, given enough time. its just really poorly soluble, not totally insoluble.

With the right reducing agents or conditions, reduction can occur at lower temperatures. carbothermal reduction is said to just be a high-temperature equillibrium reaction, for example, under vacuum where CO2 that forms has a mechanism driving it away from the oxide/carbon, or just promoting the formation of gas, you can reduce iron oxide to iron with carbon at a much lower temperature, off the top of my head, like 700C instead of over 1200C

One idea based on SO2 oxidation catalyst formulations ive seen, would be to add small amounts of iron. It will prefferentially desire the sulfate more than the lead i think, but then will also decompose right away once an exchange occurs, but, at much lower temps, lowered further by the presence of carbon too. I can imagine this just happens automatically to a modest degree in a sufficiently rusty old tin can used as a crucible. Intimate mixtures of iron and copper will do this, promoting the combustion of sulfur, as well as also oxidizing SO2 to SO3 with modest efficacy. I wanted to use this for a SO2 generator, or, pre-oxidizer stage in a contact process setup to make sure traces of sulfur fumes didnt reach the vanadium catalyst. a mixture of iron and copper results in the sulfur reactivity of one, and the thermal instability of its formed sulfate in the other, i cant imagine something similar couldnt be done with lead and its not like you can avoid getting iron in your slag unless you are using a graphite crucible or something

Hexabromobenzene - 15-10-2025 at 17:54

Quote: Originally posted by wvcruffler  
I may try both electrolysis and reduction.

I don't know why it would need to be 1000C - there are videos of small scale reduction of lead oxide using a bunsen burner. Perhaps its the conversion of lead sulfate to lead oxide then reduction of lead oxide to lead metal that requires that temp? There should not be a large amount of lead sulfate in these car batteries. There will be some, but should mainly be lead dioxode and lead oxides. Now I HAVE to do this!!! I believe I will need to have the crucible closed for the lead reduction. Wish I didn't have to work this week - the weather is going to be perfect for such hijinks.

For Electrolysis
What did you use as electrodes? Did you attach your copper wire to the lead frames?
Looks like the anode and cathode are continuous with the big pile of frames and oxide. Haven't seen it done that way before. Assuming you filter and melt the soft lead after completion. What about using the oxide to make a lead salt (like lead acetateor lead nitrate) then electolysis. I'm going to be making some lead nitrate for a later experiment involving Lead Hypophosphite :D

Anyway, this is going to be a fun one. Then casting the lead into roundballs and shooting them with home made propellant will be the capper.





Yes, 4 plates with screwed copper wires were used as a current collector for a bulk cathode
A plate from a battery was used as an anode since I did not have a lead ingot at that time. I recommend soldering for good contact with the anode. Voltage can be reduced even to 3 volts. The current is limited by the size of the anode and can be very significant. With a small anode area, a lot of ozone is released

To melt sponge lead, you need flux. I recommend alkali, as well as polyethylene and flour as deoxidizing agents. Sponge lead oxidizes in air and is best stored wet. Lead should also be washed from traces of acid.
Electrolysis produces up to 100 grams of sulfuric acid from a 1kg of battery plates. There's a lot of sulfate there. Electrolysis is the most profitable option to decompose it

High temperature in pyrometallurgy method is used to melt slag and coagulate lead droplets


[Edited on 16-10-2025 by Hexabromobenzene]

wvcruffler - 16-10-2025 at 06:52

An interesting paper on dealing with sulfates in battery waste using oxalates, alkaline solution, and carbonates!

https://www.osti.gov/servlets/purl/1877161#:~:text=The%20desulphurization%20of%20lead%20sulfates%20represented%20by,conversion%20to%20lead%20carbonate %20in%20carbonate%20solutions.

Oxalic acid is cheap as dirt

[Edited on 16-10-2025 by wvcruffler]

It appears one may be able to convert the lead oxides to lead oxalate as well. So then could heat the lead oxalates to decompose to lead oxide then reduce with heat and carbon to lead and CO. Going to order a few pounds of oxalic acid. If it doesn't work I'll just use to to take some algae off the ramp to my porch!!!

DrP

[Edited on 16-10-2025 by wvcruffler]

Metacelsus - 16-10-2025 at 08:30

Lead is no joke, especially when you're working with kilograms of the stuff. I'm all for home chemistry, but this sounds like a great way to give yourself lead poisoning, and even if you wear a respirator the whole site will get contaminated. Actually lead acid battery "recycling" is a major pollution source in 3rd world countries without environmental regulations.

So if you want pure lead for casting it's best to just buy it instead of trying to get it out of the old batteries.

Hexabromobenzene - 16-10-2025 at 21:15

Lead poisoning is difficult to achieve in the short term. This can happen if you smelt it indoors or work with soluble lead salts without taking precautions. This is why I prefer to use lead anodes, which are partially corroded, rather than making anodes from lead dioxide I'm also trying to develop a durable carbon anode.
Lead contamination isn't that bad either. If a few milligrams of lead compounds get into a crack in your flooring, it will remain there for centuries without any danger.
Even if something falls into the sewer, it's not that bad, since most of it will settle in the pipes. And there are a lot of heavy metals there.
Some serious consequences are possible if you dump waste directly into the environment.
Lead is nasty stuff. But it's not chrysotile asbestos or mercury.

[Edited on 17-10-2025 by Hexabromobenzene]

MrDoctor - 16-10-2025 at 23:58

the wave of violence and serial killings in the american midwest from the 50s-70s was in part attributed to the severe contamination of lead in the soil and air. The reason the childhood homes of almost every famous serial killer from that era no longer exist is because they were hotspots in almost all, the same region, and targeted in the soil remediation program that i think occasionally still is active today. iirc bundy grew up directly downwind and within direct line of sight, with the towns metal foundry. granted the bar is low but, it was still so contaminated, it wasnt feasible to attempt to decontaminate it so it got disposed of somewhere like a desert or something in a massive plastic lined hole.

Anyway, the only reason you say its difficult to get lead poisoning or severe acute exposure is because it hasnt converted to any particularly water soluble forms yet, so yeah, shy of accidentally inhaling the dry sulfate, standard PPE mitigates all the risks which are low. but do not mistake that as the baseline for lead. and especially if dealing with potentially contaminated lead. if you attempted to salvage from a lead battery that had been set on fire, since all the lead would remain behind, there would be a substantial diverse array of lead carboxylic acids, polypropylene rearranges into just about everything while it burns, and many of them would probably be water soluble enough to be dangerous on skin contact.

As for if lead is hazardous spilled into your soil, it has a way of getting into you over time, at a rate that is sometimes rather appreciable given how slowly it clears out of your system. One way or another people with contaminated land can be spotted with a blood test even if they dont drink from a well or grow vegetables in the soil. Theres places in the world with radioactive dust storms becase the topology concentrates uranium oxides into surface dust/soil from depleted uranium munitions used there or in adjacent countries, i think another is just from a dried out inland sea or something. Lead doesnt really go anywhere and its always in a form that is ready to stick to you in the event you ever interact with it. hell, consider the dust from mowing your lawn, from not only the dust, but the aerosolized grass too, and the bleeding juices of the freshly cut blades that get all over your shoes.

wvcruffler - 17-10-2025 at 04:05

Well, lets agree that we aren't going to be spraying the lawn with the leftover lead oxide. I don't think this battery project is going to impact the environment in a more meaningfuol way than the vehicle junkyard that used to be on this same piece of reclaimed land. I do get the occasional lead level because I am an avid shooter and because I do cast my own lead bullets. I use PPE when I cast including a p100 respirator when I am smelting dirty lead. I do have a "naughty bits" bin for things that will need to go to hazmat handling at some point but that volume is in ounces presently.

I'll do my due dillignece to protect the groundwater here. I am not a bit concenrned about my lead exposure - have been doing this a while with no change in my lead level despite pretty frequent exposure because I do use PPE. I am a physician so I do understand the risks of heavy metal exposures. Doesn't dissuade me from trying the occasional project.

I'll update this thread when I get around to trying this. Did order some oxalic acid. Even if it doesn't work I do have other tasks for it on the farm. This week I am going to pick up a broken muffle furnace that is capable of 1200C. It's actually the door latch that broken so should be able to get it sorted.

Really appreciate all the comments. I do take safety to heart.

RU_KLO - 17-10-2025 at 06:50

If oxides, sulfates and "small metal contaminations" are a problem, maybe you could process them with nitric acid.

Of course we are talking about lead (and soluble salts worst) so be aware of dangers.

As lead nitrate is soluble, and antimony (V) salt is not, maybe this could be a way to purify- (same with tin (Sn)) NOTE: antimony (III) salts are soluble in diluted nitric acid, but antimony (V) not : gelatinous precipitate of hydrated antimony pentoxide, so concentrated nitric acid should be used. (or a way to oxidise it to antimony (V).

WARNING: not only lead is poisonous but NO2 from nitric acid + metal are also. So do it outside or fumehood and have proper protection.

Some times (it happen to me) the production on NO2 is like a uncontrolled volcano. Add the nitric acid dropwise with care.

So you can procees your slag with this, to recover more lead.

Lead (II) nitrate is a very good (although very poisonous) reagent for lead ions. Its soluble. You could make lead electrodes for electrochemistry and also you can decompose it with heat to make lead oxides (PbO).



RogueRose - 17-10-2025 at 07:07

Let me warn you of this. It is not as easy as you think. I have a number of threads on this board & many others regarding this exact issue, take a look.

The amount of "free" lead in lead acid batteries is about 2-5? total weight from my estimates. The rest is near impossible to extract w/o a lot of work and a reducing material (charcoal hasn't worked for me). I've tried at least 10-15 different times using excessive amounts of fuel/heat and many setups to tryto use CO as a reducer. It is extremely cumbersome w/o a perfected setup as you end up creating more oxides as you try to melt.

My suggestion is to try to buy wheel weights or go find a roofer or plumber and ask if you can buy the lead scrap. Many of them work with lead and it's a very nice, soft pure lead. The batteries are absolutely not worth it unless you are building a setup to process them regularly & in moderate volume.

Now, if you decide to continue on with this and are successful, PLEASE message me!!!! It would be nice to have a souce of lead like this, and on the surface, it seems like it should be easy. I was warned by many people before I tried many times, but I thought I knew better, but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).

Good luck & let us know how you make out!

Sulaiman - 17-10-2025 at 08:44

Quote: Originally posted by RogueRose  
... but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).
(insert expletive here) !
As I too have a good supply of lead oxides & extras,
I was hoping that a carbothermal reduction would be straightforward :(

wvcruffler - 17-10-2025 at 09:23

Quote: Originally posted by Sulaiman  
Quote: Originally posted by RogueRose  
... but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).
(insert expletive here) !
As I too have a good supply of lead oxides & extras,
I was hoping that a carbothermal reduction would be straightforward :(


Roger that. Were you using a melting furnace? Option 2 is electrolysis - but thats a shit ton of oxide/oxalate to electolyse!! I am going to make some lead electrodes as I want to do electrolysis on the battery acid to see what's in there.

Down the road I am keeping an eye out on GovDeals for a GC/MS seteup with some life left to play with. Have seen operational ones in the low hundreds.

Anyway plan is only this one battery so onward I go.

RogueRose - 19-10-2025 at 13:04

Quote: Originally posted by Sulaiman  
Quote: Originally posted by RogueRose  
... but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).
(insert expletive here) !
As I too have a good supply of lead oxides & extras,
I was hoping that a carbothermal reduction would be straightforward :(


I thought it would be pretty straight forward as well, but there is something very strange with the non PbO2 plates, the grey colored plates. These seem to be impervious to heat. It's almost as if they are lead sulfate or something (I know they aren't). They just don't melt even using MAPP or acetylene.

If you want to do this, I think you need a custom setup where there is NO O2 getting to the lead & either CO or H2 is passing over very hot (1900F+) lead. I'm not positive of the temp, but that's the temp needed to reduce oxides, but it doesn't seem to work. I might be doing it wrong, but you would think melting lead would be pretty straight forward, but it's something about these batteries that I don't understand. I've even tried "new" batteries (less than a year old) that had a damaged case, and it wouldn't melt.

If you decide to try this, LMK, b/c I'm not done skinning this cat. If you can come up with an apparatus that could be made from pipe & welding, I'll make one and give it a try. I'd like to use charcoal or coal or possibly woodgas (but would have to make a woodgas generator, but that would be useful as well..).

Anyway, LMK if you give this a shot.

RogueRose - 19-10-2025 at 13:11

Quote: Originally posted by wvcruffler  
Quote: Originally posted by Sulaiman  
Quote: Originally posted by RogueRose  
... but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).
(insert expletive here) !
As I too have a good supply of lead oxides & extras,
I was hoping that a carbothermal reduction would be straightforward :(


Roger that. Were you using a melting furnace? Option 2 is electrolysis - but thats a shit ton of oxide/oxalate to electolyse!! I am going to make some lead electrodes as I want to do electrolysis on the battery acid to see what's in there.

Down the road I am keeping an eye out on GovDeals for a GC/MS seteup with some life left to play with. Have seen operational ones in the low hundreds.

Anyway plan is only this one battery so onward I go.


Check out Public Surplus as well. I bought a lot from them. IDK where you live, but I've bought a lot from the DC suburbs school's that have some great equipment and it sells for good prices. I think they only used PublicSurplus but I'm not sure.

As for electrolysis, I've considered this but I just hate dealing with lead salts in solution. dealing with melted lead is bad enough, I despise the thought of dealing with the waste from the electrolysis.

I'm very serious about finding companies near you that do stained glass restoration, roof restoration and plumbing restoration. I work for a contractor and we do some roofing and we come across windows with lead in them as well as lead roof flashing & lead bath tub liners. Lots of very large sheets of pure, soft lead.

Unless you want to be able to convert the batteries to lead in the future, the juice isn't worth the squeeze, unless you are doing it for to learn more about how this type of lead reacts (or doesn't react in this case).

BTW, I've tried submerging that non oxide plates in excess of melted lead (like a 20 or 30 : 1 ratio) at various temps from 1200 up to 1900+, and it just floats on the top laughing at me. I have video of it I can post if I dig it up..

wvcruffler - 19-10-2025 at 15:03

Quote: Originally posted by RogueRose  
Quote: Originally posted by wvcruffler  
Quote: Originally posted by Sulaiman  
Quote: Originally posted by RogueRose  
... but I was also told that it was as easy as just heating it with a torch (majority of people proclaimed this).
(insert expletive here) !
As I too have a good supply of lead oxides & extras,
I was hoping that a carbothermal reduction would be straightforward :(


Roger that. Were you using a melting furnace? Option 2 is electrolysis - but thats a shit ton of oxide/oxalate to electolyse!! I am going to make some lead electrodes as I want to do electrolysis on the battery acid to see what's in there.

Down the road I am keeping an eye out on GovDeals for a GC/MS seteup with some life left to play with. Have seen operational ones in the low hundreds.

Anyway plan is only this one battery so onward I go.


Check out Public Surplus as well. I bought a lot from them. IDK where you live, but I've bought a lot from the DC suburbs school's that have some great equipment and it sells for good prices. I think they only used PublicSurplus but I'm not sure.

As for electrolysis, I've considered this but I just hate dealing with lead salts in solution. dealing with melted lead is bad enough, I despise the thought of dealing with the waste from the electrolysis.

I'm very serious about finding companies near you that do stained glass restoration, roof restoration and plumbing restoration. I work for a contractor and we do some roofing and we come across windows with lead in them as well as lead roof flashing & lead bath tub liners. Lots of very large sheets of pure, soft lead.

Unless you want to be able to convert the batteries to lead in the future, the juice isn't worth the squeeze, unless you are doing it for to learn more about how this type of lead reacts (or doesn't react in this case).

BTW, I've tried submerging that non oxide plates in excess of melted lead (like a 20 or 30 : 1 ratio) at various temps from 1200 up to 1900+, and it just floats on the top laughing at me. I have video of it I can post if I dig it up..


So my current plan is to drain the sulfuric acid to clean up later
Then open the battery into a tub and wash the lead parts/sulfonated lead plates with oxalic acid to convert them to lead oxalate and make sulfuric acid as my byproduct. Will probably use an excess of oxalic acid which I can separate from the sulfuric acid later by precipitating out some other insoluble oxalate.

Then will try to wash and filter the "powder" and plates and then dry in the oven (kiln) at a low temp. At that point I may melt off the klead that I wasn't able to easily separate. Then im going to pulverize the dry compund (wearing my proprer PPE) which should mostly be lead oxides and oxalates. Weig, mix with an excess of carbon and stick in furnace in a covered retort and see what happens!!!!

So I was exploring other reducing agents and came across an article suggesting aluminum metal to reduce lead oxide. Lol. Yeah, I've done iron oxides and aluminum before......

Anyway this is just a one-off project. I really hope de-sulphurizing the lead will get the reducing temp down. I'll know soon enough.

bariumbromate - 20-10-2025 at 14:07

most large hardware stores sell large rolls of lead roof flashing.

RU_KLO - 29-10-2025 at 09:28

VERY DANGEROUS
Molten sodium hydroxide and lead

From this patent:

"This invention relates to a process for converting lead oxide to lead and particularly to the treatment of lead oxide slag materials"

Briefly, such process comprises mixing the by-product lead with at least 2% by weight of sodium hydroxide, heating the mixture at a temperature of from 327 C. to about 450 C. until the particles of by-product lead melt and coalesce, settling the molten mixture to form a lower layer of molten metallic lead and an upper layer of molten sodium hydroxide containing the lead oxide, and then separating the layers

"
https://patents.google.com/patent/US2691575A/en

In the same patent, there is a way to convert lead oxide to lead, but you need sodium metal.


Do it with care and protection:
(NOTE: I did not done this process, so hear other voices, because molten NaOH is no joke)

As vessel, maybe an graphite crucible (used for melting), and probably you will need to sacrifice it.

Sulaiman - 18-1-2026 at 23:02

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.?

RU_KLO - 19-1-2026 at 10:15

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?)











pesco - 24-1-2026 at 15:54

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 :D


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 :D
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 :D

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 :D) 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 :D

[Edited on 24-1-2026 by pesco]