# Concentrated Sulfuric Stripping Cell - Anode basket material



## snoman701 (Mar 11, 2017)

What are my options here?

I know that some have used copper mesh.

Can I use perforated steel?

I know that stainless is a no no due to nickel.

Plastic with conductive "dangler" - what grades plastic? Teflon, CPVC "and others". 

Essentially, I want to make a rotating drum, but don't know what to fabricate the drum out of. If I had the money to order teflon screen, I'd do it, but alas, I don't right now. 

I'd love to make a little platinum drum, but lacking the money for teflon, well...

I've got copper screen, and I think the steel is OK as an anode, but I'm not sure!?!? (I know that steel is OK as a cathode, but I'm not sure on the anode side...it has been used as the conductive dangler on some cells that I've seen, but that's different than using a large piece of it. 

And I've read about faraday cage with copper screen drum concerns, but if that were the case, wouldn't it also make the simple "tray" that one folds up out of the screen also not-work? The items to be stripped are on the other side of the electric field.


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## 4metals (Mar 11, 2017)

You didn't say what you were stripping, but you did mention rotating drum. 

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=85&t=22554


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## snoman701 (Mar 11, 2017)

Eh...it's gold plated pins and parts. So yes, that's my motivation. The plastic drum is what I'm after. I want about a quart, but don't know what plastics I can use. I've looked at the compatibility charts, but that doesn't really relate back to a product I'm immediately familiar with. I.e., Tupperware or Rubbermaid, etc


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## Topher_osAUrus (Mar 11, 2017)

Rubbermade and tupperware, and most all plastics are marked on the bottom. Their number is inside the recycling arrows. 1 is pet, Hdpe is 2, pvc is 3, 4 is ldpe, 5 is polypropylene, 6 is polystyrene, 7 is other.

https://en.m.wikipedia.org/wiki/Resin_identification_code


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## snoman701 (Mar 11, 2017)

None of those are compatible with concentrated sulfuric. 

Ldpe has mixed reviews, depending on resin. 


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## goldsilverpro (Mar 11, 2017)

If you can keep the solution temperature low, I think HDPE will hold up for a long time. When you buy a 55 gal drum of sulfuric, the drum is HDPE. The secret of success with the sulfuric stripper is to keep the temperature below about 105F. Too high an amperage is what heats it up. A maximum of 5A per gallon (4 liters) of solution is what I always recommend. This Amperage will also be suitable for a copper mesh basket. Anything higher, the solution could get too hot and the copper will start dissolving.

I used a polypro plating barrel for many, many cycles through the sulfuric stripper. The surface of the PP definitely was affected and it became rough and milky-white colored. However, it still worked fine and probably could have worked for many more cycles.

The requirements are different for a container used to store H2SO4 than it is for something not used to store H2SO4.


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## FrugalRefiner (Mar 11, 2017)

I agree with GSP. HDPE should be fine.

Dave

Edit to add link to SD Plastics.


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## snoman701 (Mar 11, 2017)

Yeah, I planned to put a pid controller in place to kill the power if temp went above 100 deg. In a perfect world I'd set up a 4-20 ma pid controller to automatically adjust current. 


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## Topher_osAUrus (Mar 11, 2017)

The current will adjust when deplating.
Dropping off to zero when the gold is fully gone.
(or unable to be deplated further from poor connection or being shielded by the copper basket/ faraday cage)


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## snoman701 (Mar 11, 2017)

I understand that.

What I was describing was a system that can run at maximum amperage for a given temperature. Basically, you turn it on, and it will pump out 50 amps up until the point the acid comes up to 110 degrees, then scale back amperage to maintain that 110 degrees. 

I don't like babysitting. Unless it's something that's getting digested in AR, then for some reason I like to watch the bubbles. 

If I had a constant source of pins, I'd set up a archimedes screw to "pump" the pins past the conductive dongles. Using multiple dongles, if you were to monitor the last one, to make sure the amperage was minimal, you could actually automate the rotational speed as well, to ensure that the pins are in the acid long enough to fully deplate. By using a simple vibratory bowl to feed pins, you could pretty much automate the whole process.


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## goldsilverpro (Mar 11, 2017)

snoman701 said:


> I understand that.
> 
> What I was describing was a system that can run at maximum amperage for a given temperature. Basically, you turn it on, and it will pump out 50 amps up until the point the acid comes up to 110 degrees, then scale back amperage to maintain that 110 degrees.
> 
> ...


All of this sounds like very impractical BS to me. You obviously have never used the sulfuric stripper.


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## snoman701 (Mar 12, 2017)

I've been dabbling in industrial automation for 20 years. It's as practical as the person who has the need for it, and is willing to jump through the hoops to get there. I automate processes that most would say are impractical just to save myself time.

Give me time to get my machine shop moved. I've got a notebook full of ideas right now.

And no, I haven't ran a stripping cell yet. I have the acid, but I don't have a safe enough place to run it yet. I have too strong of a respect for the acid to do it in an uncontrolled space.


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## snoman701 (Mar 12, 2017)

Don't get me wrong Chris...I understand and respect your opinion. And I totally agree that for the average refiner, it would be impractical...as the cost would make it impossible to be profitable.


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## goldsilverpro (Mar 12, 2017)

I had a 50 gallon sulfuric stripper which I ran daily for several years. For things like pins or IC package lids, I used a commercial barrel plater. It was probably a Sterling and was about 9" dia X 18" long (similar to the first one under Larger Capacity Barrels in this pdf). I bought it used. For loose, small, all-metal parts, a plating barrel is about the ultimate in automation. In most plating barrel applications, 30-40% of the parts will make electrical contact at any given time.
http://www.sterlingsystems.com/sterling.pdf

I also stripped larger parts on plating racks that I designed and built. I could get about 300 all gold ceramic ICs on a 2-sided rack. Before racking, the lids and chips on the ICs were removed by heating (melting the brazes). It took about 20 minutes to strip a rack of parts.
https://encrypted.google.com/search?q=plating+rack&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj_qfC3t9HSAhVM0WMKHSxVDh0Q_AUICSgC&biw=1138&bih=481

I used the mild steel 50gal tank as the cathode. I used a 250A, 12V rectifier in sunny L.A. and the solution temperature never exceeded 105F. I used the same solution for about 2 years and harvested the gold once or twice each month.


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## 4metals (Mar 12, 2017)

> I had a 50 gallon sulfuric stripper which I ran daily for several years. For things like pins or IC package lids, I used a commercial barrel plater.



In your stripper setup, did you allow the solids to settle or did you mechanically remove them by filtration? I have had decent luck with spiral wound polyethylene filters and was just curious as to how you removed the values from the solution.


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## goldsilverpro (Mar 12, 2017)

4metals said:


> > I had a 50 gallon sulfuric stripper which I ran daily for several years. For things like pins or IC package lids, I used a commercial barrel plater.
> 
> 
> 
> In your stripper setup, did you allow the solids to settle or did you mechanically remove them by filtration? I have had decent luck with spiral wound polyethylene filters and was just curious as to how you removed the values from the solution.


After settling, we pumped it into another tank using a small self-priming PVC (I think) pump that was maintained at the surface of the solution without disturbing the solids. Then we scooped out the solids. Probably about 2-3% of the gold left in the tank -get it next time.

Since then, I have come up with better ways. E.g., An elevated tank with a double valve drain. Or a bulkhead valve mounted an inch or so above the bottom of an elevated drum or the steel tank.

A string filter is a good idea and might be the best way. I can see leaching the gold out of the filter with AR - just get all the yellow out.


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## 4metals (Mar 12, 2017)

Thanks Chris,

Apparently you were never held to accountability for a single lot so your cleanups were not as critical. I made a setup for a guy who gets in lead trim with a copper base metal and gold plated copper wire from different customers, as well as plated contacts. 

I set up a cell which is round with a conical bottom and a water jacketed tank which continually circulates out the bottom drain and through a spiral wound filter so the cell removes all of the particulates quickly so batch lots can be run after a 15 minute filtration purge after the work is removed. This effectively allows lots to be processed from different customers in relatively rapid succession. The filter cartridges are removed and incinerated and processed in aqua regia. So every lot gets a new filter cartridge. 

The only problem is the water the acid absorbs when it stands around not being used. To address that, steam is injected into the jacket on the tank and the sulfuric is heated to drive off the water before a new batch of lots is run. The cold water chills the bath while it is tightly covered before processing starts again. 

The only part I dislike is the sulfuric. It is a nasty, powerful acid and at 96% not free rinsing so you need to be careful around it.


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## salman1122 (Mar 22, 2017)

i wanna make sulfuric cell . i could not find lead bar. can i get lead plate from lead acid batry? would it work?


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## aga (Mar 22, 2017)

salman1122 said:


> i wanna make sulfuric cell . i could not find lead bar. can i get lead plate from lead acid batry? would it work?


Probably not.

The lead in a car battery is a 'sponge' material with binders in it, also the battery chemistry dictates that the composition of the 'plates' changes depending on the state-of-charge and the age.

A scrap yard will sell you some old lead pipe pretty cheap.


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## goldsilverpro (Mar 22, 2017)

You really don't need a continuously rotating barrel. All you need is to give the barrel a turn every minute or so to change the positions of the parts. When the current starts decreasing, give the barrel a turn. The current won't penetrate deep into a pile of stagnant parts - the surface of the pile will draw most of the current.

Here's what I've thought of over the years, in its simplest form.

I have a plastic cylindrical shaped container, with a big screw on lid, about 4.5" dia X 8" long. I envision a mild steel square stock shaft, long enough to go through the bottom and the lid and sit on insulated cradles on the sides of the tank. I would grind the rod round where it sits in the cradles. I would figure a way to reinforce the plastic where the square rod goes through so the holes don't enlarge. On one end of the rod I would form a crank or I would just clamp a small vise grip on the end of the rod to turn the barrel. Quite a few holes, smaller than the parts, would be drilled in the barrel to allow the gold powder to escape. 

The parts are loaded and unloaded by unscrewing the lid. Enough parts are loaded to bring the parts a little above the shaft so the parts are always making contact with the shaft. The solution level will be a little below the shaft. The (+) lead from the PS will be connected to the rod and the (-) lead to the cathode(s). To simplify things, I would fabricate the tank out of about 1/8" mild steel and use the tank as the cathode - great current distribution. The cradles that support the rods would be insulated, of course, to isolate the rod from the tank.

If you must have continuous rotation, a rotisserie motor would probably work. You could use a steel spring to make continuous electrical contact to the rod. You might figure out a way to baffle the barrel to get better parts rotation.


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## Topher_osAUrus (Mar 22, 2017)

goldsilverpro said:


> The cradles that support the rods would be insulted, of course, to isolate the rod from the tank.
> .



Dont insult the cradles! Without them, it all falls!
Kidding

That is a pretty genius idea.


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## snoman701 (Mar 23, 2017)

Lead pipe is usually filthy. You are better off with lead sheeting removed from radiology room walls. But it has also been said that steel is fine as well.


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## g_axelsson (Mar 23, 2017)

Some old cables have a lead shield, that's what I'm using. Easy to strip, flatten and bend into any shape you need.

Göran


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## snoman701 (Mar 23, 2017)

I've been digging through my crap trying to find an appropriate barrel. Or I'll just make my own out of virgin hdpe sheet. Either way, the garage has to be cleaned first so I can make an appropriate tank. I've got a couple ounces of gold that I need to get off some industrial plated parts. While I don't want to sell it, I may anyway so that I can buy a plasma cutter. 


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## snoman701 (Mar 23, 2017)

goldsilverpro said:


> You really don't need a continuously rotating barrel. All you need is to give the barrel a turn every minute or so to change the positions of the parts. When the current starts decreasing, give the barrel a turn. The current won't penetrate deep into a pile of stagnant parts - the surface of the pile will draw most of the current.
> 
> Here's what I've thought of over the years, in its simplest form.
> 
> ...



So one of the tricks with tig welding is to just wrap the shaft with copper wire. If it makes contact in enough places, you don't get arcing that locks it together.

I like the idea, actually, really like it...but I think that instead of having to fill it to the point of the shaft, it might be easier to use a rotisserie thingie...as displayed in my attachment.

The barrel would then go over the meat spike, meaning you could run a considerably smaller amount of product. Three, or four "spikes". 

I want my machine shop...NOW.


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## goldsilverpro (Mar 23, 2017)

You could use a few links of a fairly heavy chain as a dangler. It could be made to rotate freely on the shaft. I first thought of using a threaded rod as a shaft and using double nuts (as lock nuts) to keep the chain in L/R position on the shaft but allow it to slip around on the shaft. Maybe 2 or 3 chain danglers along the length of the shaft.

I know I should do some drawings of all this stuff as it is difficult to explain in words. Maybe later.

Those rotisserie prongs could serve a double purpose - to secure the barrel in place and to provide contacts in the barrel.


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## upcyclist (Mar 23, 2017)

What about just thicker chain, thinner rod (chain link ID > rod OD)? You could slip a link of the chain through the rod between the barrel bottom and lid. Either long enough to reach from the shaft to the edge of the barrel, or twice as long and insert the shaft through the middle link.

--Eric


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## salman1122 (Mar 26, 2017)

can we tell which heat spreader of processor is gold plated without removing it?


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## jimdoc (Mar 26, 2017)

salman1122 said:


> can we tell which heat spreader of processor is gold plated without removing it?



Another double post, and even in a totally wrong section for the question.
Please find some patience, or use the search box to find your answers.


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## goldsilverpro (Mar 26, 2017)

salman1122 said:


> can we tell which heat spreader of processor is gold plated without removing it?



Any more double posts might result in your being banned.


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## philddreamer (Mar 26, 2017)

Chris wrote:


> Here's what I've thought of over the years, in its simplest form.
> 
> I have a plastic cylindrical shaped container, with a big screw on lid, about 4.5" dia X 8" long. I envision a mild steel square stock shaft, long enough to go through the bottom and the lid and sit on insulated cradles on the sides of the tank. I would grind the rod round where it sits in the cradles. I would figure a way to reinforce the plastic where the square rod goes through so the holes don't enlarge. On one end of the rod I would form a crank or I would just clamp a small vise grip on the end of the rod to turn the barrel. Quite a few holes, smaller than the parts, would be drilled in the barrel to allow the gold powder to escape.
> 
> ...


I like very much the idea!
I'll start to work on a prototype, soon... I have a 6" x 10" plastic container, with a 4-3/4" diameter lid.
I would try using a 1/2" mild steel all thread rod, so I can use nuts and washers to secure the rod to the bottom of container, and to the lid. 
Instead of chain, though, I'll try tack welding some light gauge 1'w x 3-3/4" L "paddles", (every 90 degrees) to help stir and make contact with the material as the container rotates...

hummmm, maybe use 6" or 8" PVC green pipe...

Just thinking... :mrgreen: 
Phil


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## salman1122 (Mar 26, 2017)

ok gold silver pro bann me . this forum isnt helping me any way .im gonna find my my own answers by doing some more practicals .


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## salman1122 (Mar 26, 2017)

and thanks for answering every post "dont double post it against the law, " "read hokes book" ive read it thrice . there is no answer of my questions .


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## aga (Mar 26, 2017)

salman1122 said:


> and thanks for answering every post "dont double post it against the law, " "read hokes book" ive read it thrice . there is no answer of my questions .


Double-posting is just pointless and annoying.

It's a shame you don't like the forum, but it can't please everyone - it is for people who actually do PM recovery/refining.

I got a button  http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=25369

Take a look, do the same, but bigger and better !


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## goldsilverpro (Mar 28, 2017)

salman1122 said:


> ok gold silver pro bann me . this forum isnt helping me any way .im gonna find my my own answers by doing some more practicals .



Ideally, that's how this forum is supposed to work. You search and find your own answers. If, after spending an hour or two, you don't find the answer, ask away. There is probably not one question you can think of that can't be answered by searching this forum. No one makes a penny off this forum. Asking people to take their time to answer simple questions that have answered 100 times is flat out rude.


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## snoman701 (Mar 28, 2017)

philddreamer said:


> Chris wrote:
> 
> 
> > Here's what I've thought of over the years, in its simplest form.
> ...



Phil,

US Plastics, $10

https://www.usplastic.com/catalog/item.aspx?itemid=35106&catid=661

Shaft...use whatever you want. But, using a large fender washer, weld it on the shaft. On the fender washer, drill a hole or weld a 1/4" bolt to the washer so that it sticks out like a stud on Frankensteins neck.

Now, drill the hole through the bottom of your barrel (and the top), then drill another hole so that the stud on the washer will be able to poke through. The hole should be just the same size as the bolt head so that it goes in, turns a little bit, and locks on to the shaft. 

If you use the square bottle, it will be self mixing as you turn it. Then you can just have a couple pieces of chain like GSP suggested. 

The main advantage of this is that you can lift the bottle out, leaving the shaft behind...which seems like it would be easier handling after stripping when it's dripping with concentrated acid. 

Another method would be to use a holly shaft inside the bottle...which I think I like the idea of now that I've wrote it. That way it's just slide on slide off.


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## patnor1011 (Mar 29, 2017)

Not to hijack thread but can anyone point me to which power supply would be ideal for sulfuric cell? Ebay or other sites, I just cant decide what to get. I am curious to know what do you use gents.
Is something like this good to use?
http://www.ebay.ie/itm/DC-Bench-Power-Supply-Switch-Mode-Adjustable-0-30V-0-5A-CSI-3005SM-/222258217487?hash=item33bf9f420f:g:3y0AAOSwAuZX48ei


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## Topher_osAUrus (Mar 29, 2017)

I dont know about the other guys, but this is what I use Pat.




I only wish I would have been able to find a 10amp one, other than that, I have no complaints at all.. Its worked great on my silver cell, and on my sulfuric cell.

I was in a rush to get mine, and this was the only one I could find locally. Next one I buy will be a 10 or 15A model.


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## upcyclist (Mar 29, 2017)

I'm starting to wonder if a smaller (for my volume, at least) version of this bucket design, like a 2 gallon bucket, would be great for converting AgCl using iron & sulfuric, too! Minus the power supply and anode/cathode, of course.


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## goldgee35 (Dec 7, 2017)

Are Mesh and a million holes "must haves" ???> Heres what I have already built on suggestion that I should use a Sulfuric Strippin Cell for a few fully coated pins ........


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## anachronism (Dec 7, 2017)

And when you put together that rig in a pyrex cooking jar are you really sure that you knew what kind of risks you were dealing with?


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## Topher_osAUrus (Dec 7, 2017)

goldgee35 said:


> Are Mesh and a million holes "must haves" ???> Heres what I have already built on suggestion that I should use a Sulfuric Strippin Cell for a few fully coated pins ........



No, its not, but the black gold mud doesnt migrate far, especially id impeded, like 95% of yours will be. Also with a basket that big, you will experience a great deal of shielding from the pins closest to the cathode.

If you dont mind stirring the pins alllll the time, renewing your electrolyte often, and having a bunch of false finishes you'll be fine. But, the "false finishes" (current drop to zero) will cause the cell to heat up more than necessary. 

Ive also come to find, with copper anode baskets, even the "proper" mesh, that some of the pins will end up with a black coating, which can rinse off then reveal a little bit more plating underneath. I bet with a truly proper rotating plating barrel it wouldnt be as much of an issue, if at all. I attribute it to electricities annoying attribute of following the path of least resistance and when most of the plating on one pin is gone, the current chooses a new path where the resistance is nil (or close to it).

Darn Ohm and Faraday, making all these laws that get in the way of my gold recovering! If they werent such a pain in the rear, Id use the sulfuric cell 99% of the time


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## goldgee35 (Dec 7, 2017)

anachronism said:


> And when you put together that rig in a pyrex cooking jar are you really sure that you knew what kind of risks you were dealing with?



I'm just assembling some ideas I'm many steps from actually using it... these things take proper planning and sage advice :wink: :wink: 
but uhmm pyrex worked for this guy https://www.youtube.com/watch?v=yb6xPB6IHGA he seemed to have few if any probs.... ; Also can The Sulfuric acid Cell hurt ya if you respect it by using it safety? (use acid safe utensils, watch the temperature and use a catch bowl etc... )... right ?? ?


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## goldgee35 (Dec 8, 2017)

Topher_osAUrus said:


> goldgee35 said:
> 
> 
> > Are Mesh and a million holes "must haves" ???> Heres what I have already built on suggestion that I should use a Sulfuric Strippin Cell for a few fully coated pins ........
> ...




okay so maybe cutting the anode down and punching a lot more holes in it may help?????...


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## nickvc (Dec 8, 2017)

One point to remember about the sulfuric cell is that it needs to be sealed when not in use for a good reason, concentrated sulfuric is very water hungry and will absorb water from the atmosphere which means that the cell will not work efficiently unless you re concentrate it by heating it and hot concentrated sulfuric is not the nicest or safest to be around. 
I would advise to have a deeper vessel to use and wear gloves and eye protection when using it, the cell works well if built and run correctly but you are using a very nasty acid so always exercise care when using it.


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