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plante1999
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A day I will use my lead battery to make lead acetate but I can get only 10% Acetic acid (vinegar) . I thing if I mx conssetre acetic acid and NaClO3
i could disove lead.
I never asked for this.
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blogfast25
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Well, well, well. On icing almost the whole mass crystallised out into a snow white crystalline mass with maybe only about 40 - 50 ml of mother liquor
left:
This stuff will now be isolated, washed and weighed for yield determination.
I’m also wondering whether the lead sulphate in a spent and discharged battery could be converted to ‘white lead’ (basic lead carbonate) by
treating it with hot soda:
3 PbSO4 (aq) + 2 Na2CO3 (aq) + 2 NaOH (aq) === > (PbCO3)2Pb(OH)2 (s) + 3 Na2SO4 (aq)
… because lead sulphate is slightly soluble in water. The basic lead carbonate should be soluble in strong acetic acid.
Or rewrite as:
3 PbSO4 (aq) + 3 Na2CO3 (aq) + H2O (l) ==== > (PbCO3)2Pb(OH)2 (s) + 3 Na2SO4 (s) + CO2 (g)
I recrystallised the lead acetate after washing it with small amounts of iced water to get rid of the excess HAc, then added a small amount of DIW and
heated lightly until complete dissolution occurred. On cooling the product crystallised in about 30 seconds flat, with crystals growing radially from
crystal nuclei at a rate of approx. 1 mm/s! The structure can just about be seen with this resolution:
[Edited on 18-9-2011 by blogfast25]
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dann2
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Acetic acid is becoming more easily obtainable as an organic (green) weed killer. It is available as a 50% solution.
A mixture of Sodium Nitrate and HCl acid will dissolve Lead. Careful of the brown fumes.
Would Ammonium Nitrate do instead of the Sodium?
Dann2
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blogfast25
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Quote: Originally posted by dann2  |
Acetic acid is becoming more easily obtainable as an organic (green) weed killer. It is available as a 50% solution.
A mixture of Sodium Nitrate and HCl acid will dissolve Lead. Careful of the brown fumes.
Would Ammonium Nitrate do instead of the Sodium?
Dann2 |
Yes, but what would you obtain? Lead nitrate is far less soluble than lead acetate and it’s the latter I’m trying to make, in various ways.
My lead, which really is from the connector part that connects the cells, doesn’t even easily dissolve in hot 70 % HNO3: reaction starts on heating
but more or less dies after about 30 min.
The green weed killers are most very weak solutions of pelargonic acid soaps (or fatty acids of similar length), a few percent. Acetic is used too but
at 50 % that’s a ‘human repellent’! Various acetic acid strength grades are cheap on eBay.
Conversion of PbSO4 to lead basic carbonate (‘white lead’ - vernacular)
I’m interested in converting the lead (II) sulphate from my spent lead battery to lead (II) acetate.
Yesterday and today I explored the following displacement reaction:
3 PbSO4 (s, aq) + 4 Na2CO3 (aq) + 2 H2O (l) === > (PbCO3)2Pb(OH)2 (s)+ 3 Na2SO4 (aq) + 2 NaHCO3 (aq)
… taking advantage of the slight solubility of PbSO4 and the complete insolubility of ‘white lead’.
To that effect 3.25 g of PbSO4, 3.4 g anh. Na2CO3 and 17 ml of water were mixed in a 1” test tube. The amount of soda is almost 3 times the
stoichiometric amount. The test tube was heated on steam bath for about an hour, and then allowed to cool and stand overnight.
The resulting precipitate was the filtered off, setting aside the first portion of filtrate and carefully washing the filter cake with multiple
aliquots of hot DIW until it ran almost neutral and no bubbles formed with strong HCl (evidence that soluble carbonate had been eliminated).
The filtrate set aside was first neutralised slowly with strong HCl until no more bubbles formed and the solution reacted strongly acidic. It was then
tested with Cu(NO3)2 for residual carbonates and tested negative, then tested again with conc. CaCl2 which caused a shed load of white CaSO4 to
precipitate. It appeared the anticipated reaction had proceeded.
The filter cake had in the mean time been dried on filter, on a low setting hot plate and two medium pinches were added to 2 test tubes and a little
water added: this stuff appears to be almost water repellent! The lead sulphate I started from did not show this.
Adding 38 % HNO3 to the first, fizzing started, then subsided and a perfectly clear solution resulted. To the second tube, some glacial acetic acid
was added. That was noticeably slower and needed a little heat but it too resulted in a perfectly clear solution. All 3 test results are strong
evidence that the displacement reaction had proceeded to completion.
The next step will obviously be to test this on battery lead (II) sulphate.
[Edited on 21-9-2011 by blogfast25]
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sxl168
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I've done this before on a larger scale and it works fine. I removed 2 car batteries worth of positive plates and tossed them into a 5 gallon bucket.
I then filled with water so the bucket was about half full. Tossed in an 5 LB bottle of pool pH plus from Wal-Mart, stir well for an hour or 2. Note
that I didn't need to add heat as dissolving that whole bottle increased the temp of the solution to about 50-60C. I then let the bucket stand for a
day, stirring once in a while. Decanting off the liquid, I recrystallized it twice to get a few pounds of crystal clear Sodium Sulfate. Some leftover
Sodium Carbonate was also left after crystallization, but amounted to less than 50g or so. Treating the solids with vinegar/acetic acid produced large
amounts of lead acetate.
I process the negative plates differently because they can be easily electrolyzed (in distilled water/dilute sulfuric acid) to remove the sulfate, and
the process produces sulfuric acid at the same time. I use one of the battery posts as an anode when doing that. I did it slowly when doing mine, one
plate at a time each taking 24 hours. The process is completed once hydrogen is evolved on the negative plate, or if you have a DMM, the voltage of
the cell rises from the nominal 2.0-2.2 volts to 2.4-2.6 volts. I was using about 50 mA/cm^2 anode current density for those numbers. The voltages
will be much higher if the ion concentration is low, such as when you first start the run. I ended up with about a 40% sulfuric acid solution once the
last plate was finished.
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blogfast25
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| Quote: Originally posted by sxl168 | I've done this before on a larger scale and it works fine. I removed 2 car batteries worth of positive plates and tossed them into a 5 gallon bucket.
I then filled with water so the bucket was about half full. Tossed in an 5 LB bottle of pool pH plus from Wal-Mart, stir well for an hour or 2. Note
that I didn't need to add heat as dissolving that whole bottle increased the temp of the solution to about 50-60C. I then let the bucket stand for a
day, stirring once in a while. Decanting off the liquid, I recrystallized it twice to get a few pounds of crystal clear Sodium Sulfate. Some leftover
Sodium Carbonate was also left after crystallization, but amounted to less than 50g or so. Treating the solids with vinegar/acetic acid produced large
amounts of lead acetate.
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Thanks sxl, that’s very much how I plan to do it today. I won’t be separating the lead from the lead sulphate and even heat might not be necessary
although it would speed up things a bit. I was thinking of using an excess (as in the test) of soda, then simply reusing the solution several times.
Your pH pool plus was NaOH I gather from the temperature increase (solvation energy), right?
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sxl168
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No, the pH Plus was ordinary Sodium Carbonate. It does generate a lot of heat when it dissolves in water, not as much as NaOH, but still significant
when using the large quantities involved. I forget where I saw it now, either the label or the MSDS for the product clearly indicated that it will
substantially heat water if the volume of water dissolving it is low. I'm sure some of the heat generated was the rapid chemical reaction between
Sodium Carbonate and the fine particles of Lead Sulfate and leftover Sulfuric Acid too. I just remember it taking only about a minute for the water
temp. to jump from 20C to 50-60C.
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sxl168
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I just wanted to comment also that I came across some patents and research papers that use a similar process for wet process recycling of batteries
and they warn that high pH levels over 11 along with high solution temperatures and long contact times would produce water soluble plumbates. You may
want to be careful how much Sodium Carbonate excess you add because of that. From what I read, keeping solution temps. under 70C, contact time under 2
hours, or a final pH of under 11 keeps soluble plumbates from forming.
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dann2
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| Quote: Originally posted by blogfast25 | | Quote: Originally posted by dann2 |
Acetic acid is becoming more easily obtainable as an organic (green) weed killer. It is available as a 50% solution.
A mixture of Sodium Nitrate and HCl acid will dissolve Lead. Careful of the brown fumes.
Would Ammonium Nitrate do instead of the Sodium?
Dann2 |
Yes, but what would you obtain? Lead nitrate is far less soluble than lead acetate and it’s the latter I’m trying to make, in various ways.
....
The green weed killers are most very weak solutions of pelargonic acid soaps (or fatty acids of similar length), a few percent. Acetic is used too but
at 50 % that’s a ‘human repellent’! Various acetic acid strength grades are cheap on eBay.
.....
[Edited on 21-9-2011 by blogfast25] |
The Acetic acid weed killer is available at 50% solution strenght. You have to water it down yourself when it comes to actually using it as a weed
killer. It a ready OTC source of Acetic acid if used in your neck of the woods.
Would the mixture of HCl acid + Ammonium Nitrate be like poor mans Aqua Reiga.
You would end up with Lead Chloride, then go to Lead Carbonate (via Sodium Carbonate or bicarbonate) and then into Lead Acetate. The Nitrogen and the
Ammonia going away? It's just that Ammonium Nitrate may be easier to come by than Sodium Nitrate.
The origan recipe using the Sodium Nitrate + HCl comes from here:
http://www.oxidizing.110mb.com/chlorate/leaddiox/pbnitrat.ht...
Down the page a bit (not my work BTW)
You eventually get to the Lead Acetate via the Carbonate
Dann2
[Edited on 22-9-2011 by dann2]
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blogfast25
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@ sxl:
Your 'pH up' must have been anhydrous Na2CO3 then: that does generate heat when rehydrated. I use Na2CO3 decahydrate, not much solvation enthalpy
there. Some heat would come from the reaction, yes.
One of the reasons I used Na2CO3 was that it's less likely to generate plumbates, which acc. my lit. research really only form with 50 % NaOH (or KOH)
or so. The CO<sub>3</sub><sup>2-</sup> is too weak a base to reach to high concentrations of OH<sup>-</sup>,
needed to form Pb(OH)6(2-) anions.
[Edited on 22-9-2011 by blogfast25]
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sxl168
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I found the pdf that I was trying to cite in the previous post. It can be found here and has decent info:
Recycling ULAB's
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blogfast25
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Thanks both dann2 and sxl for these links, very useful indeed...
sxl: my excess of Na2CO3 would indeed appear to have been unecessary but also unlikely to lead to plumbites being formed. These require extremely high
levels of OH- that even a strong solution of carbonate cannot deliver because carbonates are weak bases.
[Edited on 23-9-2011 by blogfast25]
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blogfast25
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Well, well. It looks like my defunct lead battery hadn’t been discharged because there no lead (II) sulphate in the first cell I broke into. I found
this battery years ago, drained off the acid and thought no more about it until recently. So that rather buggers my plan to convert the sulphate to
white lead, unless I want to attempt to fully discharge the two remaining cells. But she may be faulty in other ways so I’m not chancing that.
That leaves only to try and improve dissolving process for the actual lead, something I’m having trouble with. I’ll have to revisit using
home-brewed aqua regia, based on 1:3 nitric/hydrochloric but with 70 % nitric instead of fuming. Nitric alone dies quickly against this particular
alloy. 50 % acetic with gradually added 35 % H2O2 might also be worth reconsidering.
Any decent ideas welcome…
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sxl168
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I wouldn't judge the lead sulfate by visual inspection. I've seen nice silver-grey battery plates that were completely discharged as I found out when
I charged the plates. The lead sulfate is a surface layer only on the Pb/PbO2 particles and is mostly transparent unless it is thick (Sulfated
battery). If your battery has been sitting around for 2 years as you have said, it's pretty much guaranteed that it to be at over 50% discharged.
If you are just trying to get Pb into solution, household bleach worked for me in the past. The key is to stir while adding and only add 1% vol./vol.
of bleach at a time and let it react. This will keep most of the Chlorine which will be generated in solution to eventually react with Pb/PbO2. It's a
slow process but worked well for me. Works well on other metals too like Ni, Co, Fe, and Cu. Warm the solution up to 50C or so also to increase
solubility of PbCl2, decant, cool to 1C and collect PbCl2 crystals. Reuse the liquid to dissolve more. Don't get too hot as solubility of Chlorine in
water drops drastically above 50C. Your method of using H2O2 should work fine also, but I find H2O2 a bit expensive to use. You can use Epsom salt for
a poor man's way to precipitate PbSO4 if you wish from PbCl2 solution, the reaction may take 15 min to kick in, but settles fast once it does.
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sxl168
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I forgot one added bonus of the PbCl2 route is that so long as the crystals are cleansed with cold distilled water, you will be rejecting the Ca and
Sb alloys present in the batteries.
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blogfast25
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@sxl:
I know what you mean about the sulphate but I actually treated some of the (supposed) sulphate with carbonate and obtained absolutely nothing. On
closer inspection of the material and a few tests with nitric acid, one can only conclude it is almost 100 % lead. On the plus side: that means I have
also PbO2 which is easy to convert to sulphate plus oxygen with hot sulphuric acid.
Regards the dissolution of lead metal in acids, I’m probably a little unrealistic in terms of expected speed and my memory of past successful
attempts must be playing up a little.
Still, a proper quantitative test with 8 g of battery lead and twice the stoichiometric amount of aqua regia (1:3 - 70 % nitric to 36 % HCl) showed
again that this alloy is probably quite resistant to chemical dissolution. Reaction started at RT, became very swift for about ½ hour during
simmering but then more or less died and little metal had actually dissolved. After hot filtering, diluting and icing the solution, about a flat
teaspoon of PbCl2 was obtained. Disappointing yield! This is a slow boat to China…
I’m now pretty convinced, including from reading those links that the ‘fastest’ route to dissolving lead metal is probably as follows. Use a
large excess of an acid (at least twice stoichiometry), HCl or HAc, and add the metal to it at 50 - 80 C (avoid boiling). Then start adding small
aliquots of a suitable oxidiser (HNO3, H2O2, perhaps as you suggest hypochlorite), allowing each aliquot to react away before adding the next one. Use
total reflux to maintain acid strength as much as possible. This should dissolve the metal while maximising the efficacy of the oxidiser. But this is
nothing like dissolving for instance copper or nickel in nitric acid: it’s slower and more finicky.
I’ve just ordered some pure lead (99.5 % lead) from eBay to see if the alloying elements really have much influence on the rate of dissolution.
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blogfast25
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I tested the ‘PbO2’ plates and it was quite disappointing. 2 x 5 g of material was subjected to strong H2SO4 and strong HNO3 (ample quantities) in
very comparable conditions (back to back). Both react as known with evolution of oxygen, the nitric reacting much more vigorously. But there’s not
much PbO2 there, it’s quite superficial and reaction stops after short time, leaving behind a bit of white PbSO4 and dissolved Pb(NO3)2 and much
unreacted lead.
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blogfast25
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A test with about 9 g of lead powder (99.5 %, 300 mesh) with 25 ml of 70 % nitric acid was quite revealing. The powder form makes it an unfair
comparison of course but it’s interesting nonetheless. The powder was so reactive the acid had to be added gradually, at least at first. Reaction
was vigorous and a whitish precipitate formed almost immediately. The reaction was strongly exothermic (aided also by the formation of a crystalline
solid), then dies a little but was resuscitated on heating. I then gradually added small amounts of water, keeping the heat on. The precipitate
gradually dissolved until at about 70 ml total volume only some turbidity remained. It hot filtered to clear (#1 filter) easily, then the filtrate
started ‘snowing’ white Pb(NO3)2 crystals, even faster when half of the tube was iced. After about 1 h; about 10 g of snow white Pb(NO3)2:
Despite the bias introduced by the powder physical form, I think this conclusively proves that purish lead dissolves much more easily in
nitric acid than the lead alloy used in my battery. It’d be worth confirming this with strong HAc + strong H2O2.
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sxl168
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I was digging for more info and came across this info from Bulletin, Issues 157-161 By United States. Bureau of Mines
PbCl2 Solubility page 20 and onward. Some pretty detailed info for leaching Lead.
I also came across an old text via Google that mentions that the Antimony added to Lead does indeed poison the Nitric Acid when trying to leech Lead.
A dictionary of chemistry and the allied branches of other sciences, Volume 7 By Henry Watts
Lead page 728.
Hope this helps out some people. I'm playing with the nearly saturated salt leaching solutions at the moment.
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blogfast25
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| Quote: Originally posted by sxl168 | I was digging for more info and came across this info from Bulletin, Issues 157-161 By United States. Bureau of Mines
PbCl2 Solubility page 20 and onward. Some pretty detailed info for leaching Lead.
I also came across an old text via Google that mentions that the Antimony added to Lead does indeed poison the Nitric Acid when trying to leech Lead.
A dictionary of chemistry and the allied branches of other sciences, Volume 7 By Henry Watts
Lead page 728.
Hope this helps out some people. I'm playing with the nearly saturated salt leaching solutions at the moment. |
The solubility of Pb (II) in function of chloride concentration due to formation of chloride complexes
PbCl<sub>3</sub><sup>-</sup> and PbCl<sub>4</sub><sup>2-</sup> is shown clearly here:
http://en.wikipedia.org/wiki/Lead#Chloride_complexes
It would suggest higher solubility of lead in high concentration chloride media. PbCl2 has also been reported to be fairly soluble in conc. HCl.
Antimony as a ‘poison’ for nitric in alloyed lead? That would fit some facts here but elemental antimony reacts quite swiftly with nitric acid,
forming the insoluble oxide. In an alloy that may be very different, though…
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watson.fawkes
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| Quote: Originally posted by blogfast25 | Antimony as a ‘poison’ for nitric in alloyed lead? That would fit some facts here but elemental antimony reacts quite swiftly with nitric acid,
forming the insoluble oxide. In an alloy that may be very different, though…
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Sounds like that oxide is forming a passivation layer. Given the different crystal structures of an alloy
and of a pure metal, I find it plausible that one oxide form passivates and another does not.
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blogfast25
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| Quote: Originally posted by watson.fawkes | | Sounds like that oxide is forming a passivation layer. Given the different crystal structures of an alloy and of a pure metal, I find it plausible
that one oxide form passivates and another does not. |
But that doesn't explain why aqua regia kind of suffers the same fate: antimony dissolves in AR with great gusto, to full solubility. Also pewter
(about 95 Sn/5 Sb) does, without any residue. Both from experience...
The most reasonable assumption thus must be that alloying components like Sb do somehow profoundly alter the dissolution behaviour of lead alloys...
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watson.fawkes
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| Quote: Originally posted by blogfast25 | | The most reasonable assumption thus must be that alloying components like Sb do somehow profoundly alter the dissolution behaviour of lead alloys...
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I'm thinking by analogy with Cor-Ten steels, in which the surface oxides form a passivation layer, unlike ordinary steels. Admittedly that layer isn't as fully passivating as
alumina is, but such a kind of layer would have the effect of slowing dissolution rates, even when the substrate alloy is otherwise reactive. My
hypothesis is that it's crystal structures in the body of the alloy that are affecting the way that oxides behave on the surface. This seems very much
like a material compatibility issue in semiconductor manufacturing, where lattice spacing is one of the reasons that one material might not adhere to
another. As such, drawing the analogy to chemically-related species with different crystal structures doesn't work. In the present case, it' material
compatibility between a lead alloy and its oxides. The difference in crystal structure between Pb and a Pb-Sb system is what's at stake. The crystals
of Sb or Sn-Sb aren't particularly relevant for examining a change of behavior of the crystals of different lead alloys.
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sxl168
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I got around to processing some of the positive battery plates today and found out they will convert to PbCl2 quite readily by adding HCl solution to
them. Make sure to do this outside as a lot of Chlorine gas is given off and do it in small batches. Given the amount of Chlorine that I saw come off,
I'd say this is not a reasonable route to use if processing large batches unless you have a method to catch the Chlorine. After reacting, I had a lot
of fine PbCl2, some unreacted PbO2, and small chunks of the metallic grid that held the PbO2 in place at the bottom of my flask. The nice thing that I
noticed is that the reaction seemed to keep going even though the solution clearly became PbCl2 saturated. I just made several passes at heating to
boiling to decant off the solution, adding water to the solids, and repeating the process until the all of the PbCl2 dissolved out.
You could also probably avoid the whole Chlorine gas mess by heating the battery plates until they converted to red/yellow Lead Oxides. I'll try that
when I get another chance.
Question: You could just bubble the Chlorine in cool water and use that Chlorinated water mixed with a dilute acid to dissolve other metals such as
Copper, right?
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blogfast25
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Bit of a useless bugger though, PbCl2, you'd have to convert it to litharge (easy). That chlorine came off means that it's largely PbO2, of course. So
it's very wasteful in HCl: half gets blown off as chlorine, the other half you've gotta dispense with. Sulfuric is the better option here (for PbO2),
IMHO.
Cl2 in water? A quite weak solution, not realy useful: even if it works on copper (no idea) you'd need tons of it...
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