Sciencemadness Discussion Board

Lead compounds to Lead chloride, desulfurization and more

VanUnamed - 14-7-2023 at 03:49

Hello!
I've been doing something lately. As i want to be able to make my own storage lead-acid batteries, as the material cost is much less than buying them ready made, even accounting the energy costs, I've been studying a lot, i have a book called "Lead Acid Batteries: Science and Technology by Pavlov".

I made previous prototypes by desulfurizing grey scrap battery paste, oxidizing it (improperly) and re-pasting, curing, forming, and i got mixed results.
Anyhow, this is most likely going to be a long post, so sit tight.
I will give a short explanation for those who have no idea how a battery is actually made and constructed.

Essentially, a compound, produced via either the barton pot method, or the ball mill method from pure lead, called "leady" oxide, a mixture of mostly oxide and some free metallic lead, is mixed with 50% sulfuric acid in specific S/L ratios, pasted onto metallic lead grids, then these plates are put into a curing chamber, where high humidity and specific temperatures allow lead sulfate crystals to grow, Often seed crystals are used. afterwards the plates are dried, soaked in different electrolyte concentration, depending, and formed, and through a specific schedule the battery becomes, well, a battery.

So as I am stubborn person that wanted to do this anyway despite the difficulty and most gravely, by ignoring or not knowing instructions, i did get 2 prototypes to work at 50% the expected capacity to then crumble. another one got to 90% the expected capacity but crumbled after 15 cycles. the last one i made, adding 4BS seed crystals, did the correct curing, and then it was impossible to form. I wronged the s/l ratio and added lignosulfonates to both negatives and positives (when this is present, 4bs crystals don't form).

So as now I wanted to do things better, and more accurately and the book i mentioned, provide serious insights. i will share what i am doing as of late to increase success rate.
I also discovered that certain contaminants, that are always present in scrap batteries active material, are a BIG NO NO, such as antimony. So i decided to go with the "let's try to use a purified version of lead and not confuse results with unknown.
So i got negative plate material, milled to a fine consistency with my ball mill, did the desulfurization process (even though this paper i use, the process does work, but in my opinion their s/l ratio is excessive leading to excess lead being dissolved as a side reaction) as described in this paper, https://journal.uctm.edu/node/j2008-2/15_D_Atanasova_267.pdf
Did the 118g/l 40c / 15min s/l 2.5. aka i treated 200g over 500g of solution.
The desulfurized paste is then reacted with HCl, which in theory is supposed to turn it all to PbCl2 which can then be crystallized and further turned into Pb(OH)2, which can then be gently heated and turned into Ortho PbO.

I did find that something peculiar was happening.
the immediate reaction between the paste and the HCl was quite exotermic. but its not like, all became PbCl2 in one go. It has been producing quite a bit of H2 bubbles over the course of days. If i understand correctly, the mixture of Pb, PbO and Pb(OH2), when reacted with HCl, the oxide and hydroxide react quickly, but the metallic Pb will take much much longer, even in a fine state.

another odd thing, in my batch #1 i boiled water though the material to dissolve PbCl2 and this did work, but each time, boiling water through it, must've caused some sort of side-reaction with the lead, aka, a big cloud of black. I did think at first that it was the carbon black that's used as additive in the negative plates, but it looked way too much to just be that, and i suspect it's some sort of oxidation/passivation, but i am not sure.
the plan afterwards will be to make enough PbCl2 to then be able to make a new prototype, that requires around 180g of PbO.

regarding this specific PbO:
If lead hydroxide is heated gently, it will form the orthorombic specie, the yellow type.
battery making require a mixture of tetra 80% and max 20% ortho, with some free metallic lead. So as i've been reading in the book, i could re-heat the oxide i make with the decomposition of the hydroxide in a kiln, at temperatures of around 450/460c but not more than that, or it'll turn possibly into Pb3O4, or transition to ortho.
in my previous attemps, i just used a pan, a lid, and a hob outside, but seeing microscopic pictures now, the oxide was in one case 50/50 in another, particle size too big.
I'm building a make-shift kiln with proper temperature control.

Also, to scale this process and not use large quantities of reagents, especially the locally expensive HCl, i would like to try in future this other process with FeCl2/FeCl3 and electrolysis, although i am not sure if electrolytic lead sponge can also be turned into oxide in a kiln

https://www.911metallurgist.com/aqueous-electrolysis-lead-ch...

I hope i didn't annoy, if you have any comments or ideas i'd be glad to hear!

Regards


[Edited on 14-7-2023 by VanUnamed]

Sulaiman - 14-7-2023 at 05:10

You may find this video interesting, I did
https://www.youtube.com/watch?v=FPI8H_wT_oI&pp=ygUibGVhZ...

There are others similar.

Admagistr - 14-7-2023 at 07:48

Hi! Welcome to the forum!Lead makes interesting chemistry,so we will have an expert on this element among us;)

yobbo II - 14-7-2023 at 08:06

Lead Salts preparation thread might interest you.

http://www.sciencemadness.org/talk/viewthread.php?tid=5490


I think with lead acid batteries you will not be making very compact, high output (for their weight and size) batteries.
These (modern) types of batteries (used in cars etc) are difficult to make. They also have the disadvantage of not being 'deep' cycle. They do not like being discharged completely and then recharged or being left uncharges for long periods of time. The plates will 'sulphate' and they become useless.
Home-made batteries will be bigger and more bulky then 'modern' compact batteries and will be good for deep cycling.

Hope I am correct on this!

Another book is Sectets of Lead Acid batteries my linsday publications.

more here:

http://libgen.rs/search.php?req=lead+acid+batteries&open...

Yob

unionised - 14-7-2023 at 15:57

I'm fairly sure that you don't want lead chloride in batteries.

VanUnamed - 14-7-2023 at 20:05

Traction batteries are indeed different from deep cycle one indeed.
The difference not only lays in the thickness of the plate, that often is as low as half a milllimeter. It's crystal structure. Any lead acid battery utlizes actively half, the active material. in car batteries the growth of 3BS (3 basic lead sulfate) is promoted as these small crystals aid the maximizing of the mass utilization also known as "cranking amps". Obviously this is done at a cost. what essentially keeps the paste in the grids, is crystals. smaller crystals, weaker. so they are more prone to waste away quicker. and they cant take much deep discharge as the smaller crystals expanding and contracting will have eventually cause damage.
In deep storage one, thicker plates, and some additives are used, but the most important thing, is 4BS crystals, which are much chunkier and interlock together.
THe other day, i visualized this on a macro scale, as I had a super-saturated solution of Na2SO4 in the fridge and when i dropped a crystal in there many long orthorombic crystals formed, creating a sturdy structure. the chemical is different, but the crystal thing is the same.
Quote: Originally posted by yobbo II  
Lead Salts preparation thread might interest you.

http://www.sciencemadness.org/talk/viewthread.php?tid=5490


I think with lead acid batteries you will not be making very compact, high output (for their weight and size) batteries.
These (modern) types of batteries (used in cars etc) are difficult to make. They also have the disadvantage of not being 'deep' cycle. They do not like being discharged completely and then recharged or being left uncharges for long periods of time. The plates will 'sulphate' and they become useless.
Home-made batteries will be bigger and more bulky then 'modern' compact batteries and will be good for deep cycling.

Hope I am correct on this!

Another book is Sectets of Lead Acid batteries my linsday publications.

more here:

http://libgen.rs/search.php?req=lead+acid+batteries&open...

Yob

VanUnamed - 14-7-2023 at 20:08

Oh wow, so that part of my grey lead powder that is lead will indeed take a long time to complete, as i read on the post linked (thanks btw)

" PbCl2 is easily prepared by dissolving lead in HCl of moderate strength, the reaction taking some time (few weeks). The reaction is faster when the HCl is heated. "


Maybe it will take less, as it's fine powder, who knows. I go there every 1-2hr and stir it and there are always fresh bubbles

I was also wondering something. As my main goal is to first of all, remove antimony.
I do know that in theory, HCl would form compounds with antimony or its oxide that would be highly, highly soluble, so once the solution that did the PbCl2 is removed, most if not all of the antimony should be gone.
But, can it also be that the desulfurization process with the 118g/L NaOH could also dissolve the traces of antimony present?

thanks in advance

[Edited on 15-7-2023 by VanUnamed]

VanUnamed - 21-7-2023 at 01:43

I don't get it.
I heated the hydroxide in the kiln at 460c for one hour, and the hydroxide only got yellow here and here, but no full going to orangey tetra PbO.
It's like this phase change needs oxygen and there isnt enough in the kiln. Bu Pb(OH)2 should have all the oxygen it needs even in inert atmosphere.
the material that remained white in the kiln, if heated in air, do not change much, unlike the hydroxide that becomes yellow throughout.
it's like, it did became PbO, but, the amorphous type.
I don't know what to try :(

Bedlasky - 21-7-2023 at 18:42

Do you have equipment to do titration or gravimetry to analyse your product?

VanUnamed - 22-7-2023 at 03:32

Ok, i've run some kiln test. I added various compounds to see how they react under temperature.
Now, i'm unsure what to make out of it.

IMAGE FROM IMGUR

the metallic sponge side, looks a lot like this
tetra-lead

I will perform a test. if it's PbO2 then contact with HCl will create Cl2

[Edited on 22-7-2023 by VanUnamed]

Brown stuff from metallic lead = no Cl2 gas evolved. PbCl2 formed.
Orange stuff, suspected to be Pb3O4.. Did produce Cl2.

[Edited on 22-7-2023 by VanUnamed]