+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 10 of 12

Thread: Extracting lead from car batteries

  1. #1

    Extracting lead from car batteries

    We have accumulated a large amount of old car batteries. They are in all sizes. From small that weight around 6-7 kg to large ones that are 60-70 kg heavy. We have already poured the acid from them. Now as they contain a lot of lead in them we would like to extract it. What would be the best method to do that? I was thinking of cutting the top off with an angle grinder, remove the top with all of the plates attached and then remove one by one with a saw (not with an angle grinder because it would spread lead dust all over the place). Also as there is PbO2 in there also what would be the best method from keeping it from flying all over the place while removing the lead plates?
    Metalcasting and cannons.

  2. #2
    Senior Member
    Join Date
    Dec 2006
    Location
    NJ Pinebarrens
    Posts
    1,678
    There was a thread on this very subject once and the consensus was, I beleive, that it was not worth it because on the process required to clean the lead and get it to a usable state, safely.\
    Try searching, I think it was a thread started just the same as this and not a a thread that turned to that subject.
    I don't know about where your at but here batteries are binging $8-$25 each depending on size and even lead it's self is bringing about $.75 a lb...which is unheard of, it's actually worth more than al.
    So I would just scrap them myself.

    welder19

  3. #3
    Administrator Site Admin Anon's Avatar
    Join Date
    Nov 2005
    Location
    College
    Posts
    8,067
    Blog Entries
    11
    Attacking them with an angle grinder is a very poor way to do it. You may have poured the liquid acid out, but the sludge inside is still highly acidic. You'll need some base on hand (hydrated lime is cheap, but be careful--it's liable to react violently) to neutralize it. Even pH balanced, it's still full of lead, so you don't want to be spreading it around, but until it's neutralized, it's acidic enough to burn you easily.

    The way commercial recyclers do it is to grind up the batteries and dump the whole mess in a tank of water. Lead sinks, plastic floats, and the sludge and acid stay with the water. The water is neutralized, the sludge is filtered out, and the water is then treated to reduce the lead content to safe levels, and discharged. The problem with doing this yourself is that you'll have a bunch of lead-contaminated water to get rid of, and it's going to be a pain to dispose of properly. Also, grinding up a bunch of batteries without spattering acid and sludge everywhere isn't easy.

    I hate to say it, but you're probably better off getting your lead from wheel weights or other cheap sources, and letting the pros handle batteries. As far as I know, they cost enough to industrially process that they're not even worth money as scrap (around here, at least, most places charge a disposal fee for old lead-acids, instead of buying them), so it's not an easy operation.
    The process of turning stumbling blocks into stepping stones can at times require the use of a large sledgehammer.

    Foundry Tutorial
    My Website <<Now at prometheus-foundry.com

  4. #4
    I've done it and it's allfull messy.
    I used a hatchet type of knife to cut it open.
    You can't just go around the top and pull everything out as the plastic between the plates keeps the top form it.

    At one time I had a lot of them and sold most, these were a few I had gotten lately off my own cars and I just wanted the lead for myself.

    Washing them a few times with water will keep them from burning you, let them dry if you can.
    Mine really did not have to much lead in them, most of it was the posts and top runer plates. The cell plates were grid-like and full of something that would not melt at a high heat.

    I would say just to sell them if you can, They used to go for good money but about all you get nowdays is the core fee.
    One time Wal-Mart (and others) would give you the core fee even if not buying a new battery.

    If you still want to try cutting them, I would cut the top off with a band saw.
    Heat them up, mold them out.

  5. #5
    Senior Member
    Join Date
    Jan 2007
    Location
    Coventry.UK.
    Posts
    675
    Recycling of car batteries has been a major source of pollution in the UK , the paste in the grids is lead oxide and as already stated the sludge is heavily contaminated. Given that the price of lead is so low it is doubtful that small scale reclaimation is worth the effort or the risk. It is illegal to do this in the UK just like burning off copper wire and the fines if you are caught are high , not to mention the anti-social element.
    The cases do break easily if clouted with a hammer but watch out for acid splashes. If mixed with a fair amount of powdered charcoal and heated in a closed container you may get a good percentage of the lead back in useable form.
    These days we leave them out with our trash and they are collected for recycling as the scrap dealers don't want them anymore , but like all scrap this can change over-night.
    The man who never made a mistake never made anything!

  6. #6
    Today we tried to remove the lead from a small car battery. We first broke up the outside layer of plastic with a hammer. I saw something that I thought were lead plates. Upon removing one I notices that it is a grid from lead wire and a gray powder filing the empty space between the strings. Then we burned off the remaining plastic, collected the grids with the powder and the powder that fell out. Upon melting some of the powder we saw that it is actually impure lead powder. We collected all the powder and the grids in a metal container in which we will melt it to cast lead ingots.
    Metalcasting and cannons.

  7. #7
    If I am not mistaken once you separate the lead from the plastic and acids you should be able to smelt it back into metallic lead of reasonable quality using carbon reduction. Charcoal with restricted air or a choked propane or oil flame should do the job plenty well once it reaches a suitable temperature, though I have no idea what the yields would be like.

    Lead was originally smelted like that, and I have a feeling most of our furnaces turned down to lead melting temperatures would be reducing easily.

    Though that acid is going to become a problem, in addition to the fact that battery plate lead is often spongy and would produce gassy ingots without some form of degasser in addition to having trouble neutralizing the acid without letting it eat your crucible.


    Probably doing what the others have suggested and taking them to a professional battery recycler is the best option, they usually pay $20 to $50 for them depending on how intact they are.
    The only difference between being a genius and being insane is being right.

    My Oil Burner

    Want a site of your own to document your foundry adventure?

  8. #8
    Quote Originally Posted by einstein
    they usually pay $20 to $50 for them depending on how intact they are.
    Where I live they pay 4 cents per kilogram for car batteries. Lead is around 65 cents per kilogram.
    Metalcasting and cannons.

  9. #9
    How much lead do you need?
    No man really becomes a fool until he stops asking questions.

  10. #10
    Senior Member
    Join Date
    Jan 2007
    Location
    Coventry.UK.
    Posts
    675
    20$ - 50$ ? I can get a new battery for not much more, when you COULD sell them a standard sized car battery got you 50p - about a dollar.
    The man who never made a mistake never made anything!

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts