guy - 9-6-2004 at 21:45
How do you get the carbon rods out of a battery? Do you just cut them up and take it out?
Saerynide - 10-6-2004 at 00:56
Use diagonal cutters and peel up the rim of the can, then make vertical cuts on the pulled up rim and peel the rim away from from the can. Push the
contents out from the bottom and pull off that plastic cap thing you see inside. Most of the time, the carbon rod comes out with it. If youre not
lucky and its stuck, then you gotta dig all the stuff out to get the rod. 
Geomancer - 10-6-2004 at 09:57
Yup, cut 'em up and take 'em out. Use "standard" or "heavy duty" (zinc chloride) cells, not the alkaline ones, which
don't have a rod. The cylindrical cells have a plastic wrapper over the zinc anode, which goes on top of a cardboad separator. The anode is
largly consumed once the cell is exhausted, and you may be able to take it apart with just a pair of pliers, or even strong fingers (not recomended).
Be warned, the rod seems to not like high current densities (at least as an anode), and erodes quickly.
kryss - 10-6-2004 at 12:50
cheap ones - Tescos - are using a carbon powder paste.
Cyrus - 10-6-2004 at 13:05
The rods are mixed with clay or a similar binder IIRC, have you ever tried to grind them up?- they certainly are not pure graphite! more like
gravelite.
Don't throw out the black "junk" - it's manganese dioxide, which needs cleaning as it is impure. There is more in unused
batteries of course. And save the dull metal inner liner while you're at it, don't waste zinc!
TheBear - 27-9-2004 at 11:37
I've recently opened about 20 old carbon zinc batteries which have supplied me with X hundreds of grams of MnO2 (contaminated with MnO(OH),
NH4Cl, ZnCl2). And 20 decent carbon electrodes aswell.
Any ideas for how to purify this? I read that MnO2 is suitable anode material for use in ClO3- cell. But they used Mn(NO3)x.
Can one cast an anode using molten MnO2?
[Edited on 27-9-2004 by TheBear]
neutrino - 27-9-2004 at 13:57
Zinc and ammonium chloride are highly soluble in water while MnO<sub>2</sub> is insoluble, as MnO(OH) should be, so you can simply filter
this solution. The remaining (hydr)oxide(s) can easily be dizzolved in acids (except MnO<sub>2</sub> and HNO<sub>3</sub>
to form the respective salts (although this will release a lot of corrosive fumes, so
be careful).
S.C. Wack - 27-9-2004 at 19:02
On the off-topic question of the black powder, repeated washing might get rid of nearly all of the NH4Cl, if any is present, but some seems to be
adsorbed. I say this because I've heated some with KOH after careful washing and still got a detectable NH3 odor. Its not much though. What is it
adsorbed on? -
There is also acetylene black in there. I measured it once but forget exactly how much - lets say 10% of the total weight of the powder. Easy to
figure - make some MnCl2 or MnSO4. Given that the MnO2 has something like 2.5X the density of the C, a surprising amount by volume isn't MnO2.
"Fractional decantation" might get rid of much of the C if this is desired.
I have horrible memories of the messes made in my pre- pottery supply days.
JohnWW - 28-9-2004 at 21:43
MnO2 decomposes without melting at less than 230ºC to Mn2O3, unfortunately.
John W.
sarcosuchus - 3-10-2004 at 13:06
if you need carbon rods there is all ways a welding shop were you can get what you need for cheap i found out that the one near me can order 2"
thick 3 foot long rodsfor $80 ish or so that was for some weird super high temp applications.. just fyi
Carbon rod
MadHatter - 3-10-2004 at 14:12
WOW ! That's a monster carbon rod ! My gouging rods are 3/8" x 12".
What's the name of the place where you found these babies ?
BromicAcid - 4-10-2004 at 09:36
You can also get nice graphite rods from jewlery suppliers, they use them to stir molten gold and the like. They are cheap, somewhat highly pure, and
can be somewhat large.
I also got carbon rods out of batteries, I bought a few of those lantern style batteries from a dollar store. Inside each was four long batteries in
a series. Each battery had a somewhat large graphite rod, too bad they don't hold up good in electrolysis.
[Edited on 10/4/2004 by BromicAcid]
Lantern batteries
MadHatter - 5-10-2004 at 09:59
BromicAcid, I also pulled those rods out of lantern batteries. Don't hold
up worth a damn during electrolyis. I'll stick with the gouging rods.
Obtaining electrodes.
Kamisama - 2-5-2005 at 09:59
I read somewhere that you can obtain electrodes from things such as a 12 volt lantern battery.
Anyone know more detail on this? I have somewhat forgotten details on it.
It's quite an interesting thing to me because I have a bunch of old batteries laying around.
darkflame89 - 3-5-2005 at 03:22
Batteries have zinc cover, right? Would this work all the same if one had threw the entire
battery into acid, wait for the zinc metal to dissolve. Then you will be left be a whole lot of mess, of which you can filter to get the
carbon rod and other insoluble products..
Esplosivo - 3-5-2005 at 04:59
If you try dissolving the whole thing in hydrochloric acid it will dissolved resulting in the remaing funk being starch (used as a binder) and some
graphite powder IIRC. The Mn compounds will react with the hydrochloric acid (MnO2 will liberate chlorine), therefore do this reaction outside if you
do intend to do it. I find it quite a loss of acid, although if acid is cheap and you have a well ventilated area it might yield some very good, clean
graphite rods. Hope this helps.
12AX7 - 3-5-2005 at 06:56
Right tool, totally wrong application... just get some pliers, they slide out of the MnO2 gunk easily.
Tim
tumadre - 3-6-2005 at 09:18
You must burn off the substance that permiates the carbon rod, I heat the rod to red heat before I use them. after this you can soak the rod in the
desired material-such as oil for some electrocem. cells
mn3o4 melts at 940C decomposes to mno at 1020c all decomposition of mnx make mno which melts at 1700c
try a thermite reaction with Mg-Al or NA
Battery carbon rods
MadHatter - 3-6-2005 at 15:47
If you intend to use the rods in an electrolysis cell, it might be a good idea to soak them in linseed
oil for a few days prior to use. This process certainly slows down the erosion rate on my gouging
rods.
Madandcrazy - 5-6-2005 at 06:25
Use carbon rods (from Batteries with MnO2/ZnCl2) in an electrolysis, it might be a good idea because the carbon can be easy removed from the liquid
and end products.
Certainly a slow erosion of the rods, only a catalyst function for the electrolysis ?