# Copper mesh for cell



## nivrnb

This is my cell construction, having trouble finding a cover for the cell. I just had a quick question about the copper mesh for the cell. I am using some shielding from some wire I don't have the thinkness measurements, but it will support a pretty good weight. My question is the wire mesh to thin? I have extra of the mesh if the acid eats it away to quickly. I may have to double it up. 

I made some forms for the anodes, that I will post later when I make.













Thanks for any input
nivrnb


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## Geo

check out lazersteves cell videos at www.goldrecovery.us it should help you out with your cell. i gave a description with pictures of a mesh basket that will help you out in the general tab.


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## nivrnb

Geo,

Thanks for the information; I have seen Lazersteve's videos. I am trying to make mine like his. If my screen doesn't work, I will buy some from his site along with other materials. Like the glass stirrer to move that material around. 

Thanks again
nivrnb


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## Acid_Bath76

If you're forced to use the thin copper mesh, there are some variables you might be able to control to extend it's life. From what I've read here, if you keep the solution cold, the H2SO4 isn't going to digest the copper. .. .as quickly. If you're using it for extended periods, you're probably going to have to replace it sooner. Lazersteve does his cell a certain way, and it works really well. I think I tried to reinvent the wheel with this project the first time around. I'm not going to go into it, other than to say that I now wear an additional rubber apron and face shield. Anyhow, are you able to remove the mesh easily after every deplating with it hanging over the entire edge like that? Or are you using it for larger objects? If you're trying to deplate a large object, why not just dip it in via an alligator clip? I'm just trying to understand why you would want to lay a whole sheet like that over the lip of the container. A little copper mesh basket would work well too. Just dip it in, deplate the contents within the basket, and remove. I've also heard others speak of avoiding sharp corners. For some reason those edges seem to corrode faster. Anyhow, good luck with the cell. I'm curious to see how it handles! 
I have a feeling though, that you might be having to clean some copper out of your powders when you harvest the cell


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## nivrnb

Acid_Bath76,

You said, "I think I tried to reinvent the wheel with this project the first time around. I'm not going to go into it, other than to say that I now wear an additional rubber apron and face shield." Now I understand the meaning of you name Acid_Bath76. I hope nothing serious happened.

You asked, are you able to remove the mesh easily after every deplating with it hanging over the entire edge like that? Or are you using it for larger objects? I plan on trying to deplate pins that are half/half first to see how it works. Then move on to higher grade pins. Yes I plan on moving on to using an aligator clip for all other pins, I have the time and will just do one at a time, Submerging only the very tip of the clip for each part.

You said, "I'm just trying to understand why you would want to lay a whole sheet like that over the lip of the container." I was just copying Lazersteve's cell, plus I have a lot of small pins as show in the picture below.

"I'm curious to see how it handles!" Me to!!!!! but I am doing like dry runs to see how it will work like as you can see in the photos below the small pins are coming thru the mesh, so that would mean I would have to pull these pins out with tweezers. More of a chance for an accident, I should as suggested earlier in a post to use the AP method.


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## Geo

that mesh will work ok for those pins. if a stray pin or two(or ten) were to fall off or through the mesh it will be ok until the end of your run.you can pick them out of the powder with tweezers. i usually have a few dozen get away from me before i get done. they wont hurt anything laying on the bottom of the cell as long as there's not enough to make contact with the cathode and the mesh at the same time. ill give you a heads up and a warning, never put your cell in a container with water or ice in it. adding water either as liquid or ice to hot sulfuric acid can cause the water to flash boil and blow hot acid every where. hot sulfuric acid will cause a bad chemical burn besides the thermal burn. using a mesh basket as big as the one you have will pull alot of amps if you load it with a moderate amount of pins. that will cause the acid to heat rapidly so you may only be able to do one basket every hour or hour and a half to give the acid time to cool down. still that's alot faster than AP bath. i have two cells and run them alternately to give each time to cool. also when you pull the basket out of the acid have another container close at hand with water in it to put the basket in for a rinse container, it can be plastic as long as its the durable kind and not the 5 for a dollar brand, :lol: alot of you gold will collect in this container. after you rinse have another contain you can dump your used pins into that also contains water. keeping the pins in water will prevent oxidation, somewhat, till you can see if they stripped good or need another bath. make sure your basket is dry before you put it back into the cell.


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## nivrnb

Geo,

Thank you for your safety and expertise with the cell. You can never be too careful; I work with electricity and treat every wire as if it was live. I am no where near ready to operate this device, and have to learn more. This weekend or next I am going to make and lead. I seen lazersteve place the anode into the glass of distilled water when not in use to keep down corrosion. I've seen on the net about a dry bag, basically a zip lock with desiccant inside and was wondering if you have ever tried that method?

I will make the copper mesh half the size that it is now to keep the acid cool, I have heard of someone putting the cell into ice water. This for me would be risky.

You said. "another container close at hand with water in it to put the basket in for a rinse container, it can be plastic as long as its the durable kind and not the 5 for a dollar brand, a lot of you gold will collect in this container." Should this container have distilled water in it? And then dump the used pins into tap water. Got it Baking Soda Water, for first rinse.

"make sure your basket is dry before you put it back into the cell." I plan on making two to three baskets, so that I can let the first basket dry, and place the dry one in. This is so that the acid does not become contaminated and lose its concentration?

Again thanks I hope to be able one day to give some useful advice.


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## nickvc

> Again thanks I hope to be able one day to give some useful advice.



Believe it or not you are contributing in a very positive way to the forum by posting pictures and commentary of how your proceeding with your cell, showing step by step photos and getting comments from more experienced members and adapting your design as required saves us all the time and effort to explain the why's and why nots of the whole set up to newbies. Pictures allow the less advanced members to actually see what is involved from start to finish and any pitfalls can be shown so keep posting.
I'm pleased your taking the advice about concentrated sulphuric seriously it really is a nasty acid which is perhaps the most dangerous most members use, also remember it's extremely hungry for water and will suck it out of the air if left uncovered. Always seal your sulphuric when not in use or constant heating to drive off the water will be necessary.


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## nivrnb

NickVC,

Thanks for the encouragement! Yes, these chemicals are dangerous, it is not if an accident will occur but when, when it comes, how prepared were you are for that accident. I used to work for SafetyKleen and saw some accidents. Yes, I want to document the whole experiance and share it. When all is said and done I want to post to the Gallery.  

I have to get that cover for the cell, I purchased this one at Salvation Army, thinking I could find a cover. Wrong, I keep looking but might have to break down and buy a new one. 

nivrnb


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## Barren Realms 007

nivrnb said:


> NickVC,
> 
> Thanks for the encouragement! Yes, these chemicals are dangerous, it is not if an accident will occur but when, when it comes, how prepared were you are for that accident. I used to work for SafetyKleen and saw some accidents. Yes, I want to document the whole experiance and share it. When all is said and done I want to post to the Gallery.
> 
> I have to get that cover for the cell, I purchased this one at Salvation Army, thinking I could find a cover. Wrong, I keep looking but might have to break down and buy a new one.
> 
> nivrnb



You can take some celophane wrap and put over your container to keep the water out. Be sure and put a drop of acid on it before you put it over your container to see if the acid will effect the wrap. I have mentioned a couple of times that I have put my cell in an ice bath when I am doing a lot of material. But you need to be careful when doing this.


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## seawolf

One other item to keep handy is a box of baking soda; if you get a splash of the acid on you blot it off with a dry paper towel put some of the baking soda over the splash area and add a few drops of water then wash with lots of tap water.
If you have to buy another container with a lid Lasersteve sells them as does Wal-Mart. the container you now have will work good for a rinse container for the first rinse of the basket and pins. If the new container is the same size and shape where the lids will interchange when it comes time to empty the cell the rinse container can be poured into another container. Then the bulk of the acid siphoned into the rinse container. Then the acid and powder from the cell can be added to the rinse water to start the washing process.
Mark


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## Geo

never put your basket into a rinse with water and baking soda. acids and bases do not mix well, you will get a nasty boil over. your rinses can both be tap water because at this stage your gold is contaminated already. besides gold the cell will strip nickle when the acid heats up and copper when it gets hot. remember that this step is not refining but reclaiming your gold the refining part will happen when you have the powder dry and incinerated. at that point to refine you will need to digest the gold and precipitate at least twice to make it pure.


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## seawolf

To be more clear: I said to have the baking soda on hand for splashes of acid on the body or surrounding surfaces to neutralize the acid splash, not for rinse of baskets or pins.
Mark


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## nivrnb

[/quote]

You can take some celophane wrap and put over your container to keep the water out. Be sure and put a drop of acid on it before you put it over your container to see if the acid will effect the wrap. I have mentioned a couple of times that I have put my cell in an ice bath when I am doing a lot of material. But you need to be careful when doing this.[/quote]

Barren Realms 007,

Thank you for the celophane Idea, I will give it a try if I don't find a lid. The ice bath is a great idea, you must a factory going. I believe I've seen some of your photos of it on the fourm. I hope I run into those problems in the future. :mrgreen:

nivrnb


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## nivrnb

Mark, 

Thanks for helping me saves z money, that will work getting a new dish and using the old one for the wash. Yes, I remeber seeing the acid siphoned off in Lasersteve's video using the tubing and the hemostat.

nivrnb


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## Geo

again i cant stress it enough to be very careful having water around concentrated sulfuric acid. as an experiment to show you what can happen, when you get your chemicals together, take a small glass container and place a glass thermometer in it then add a few milliliters of concentrated sulfuric in it and then add tap water a drop at a time and after each drop look at the thermometer. you will notice the temperature rise quickly. this is called an exothermic reaction.now think of what it would be like if you multiply that by a factor of a thousand or more. just be careful, no amount of gold is worth your sight not to mention your life.

after being shown the error of my ways (thank you bswartzwelder), i would like to note that the above advice should be reversed. it should be to add acid to water and not add water to acid. though the quantities are small, it could give readers the wrong information about how to dilute acid.


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## nivrnb

Geo,

Yes, most certainly I will take every precaution. I do not plan on having the cell operation for some time. I cannot stress that I am in no hurry, when I beleive I have it ready, I will post more photos before I even put the acid into it. To get everyones approval of the setup. Then I have to get my girlfriends approval. :shock: She could pull the plug at anytime.

nivrnb


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## Geo

if she smells the fumes from that cell you will be in trouble.


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## Barren Realms 007

nivrnb said:


> Geo,
> 
> Yes, most certainly I will take every precaution. I do not plan on having the cell operation for some time. I cannot stress that I am in no hurry, when I beleive I have it ready, I will post more photos before I even put the acid into it. To get everyones approval of the setup. Then I have to get my girlfriends approval. :shock: She could pull the plug at anytime.
> 
> nivrnb



Get the job done and melted and show her the bar and then see what she says. Just don't let her hold it for long, they tend not to want to give it back. It can be just as mezmerizing experience for the opposite sex as it can be for you. No telling what you might get away with while she is holding it.... :twisted:


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## Geo

ill start on this batch tonight it will take two cells and most of the night to complete it all.


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## nivrnb

I just broke the news to her, like this "It might stink a little". Tommorow I will post pics of the power supply and cables. 

nivrnb


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## rewalston

Geo said:


> ill start on this batch tonight it will take two cells and most of the night to complete it all.View attachment 2
> View attachment 1


nice mountain you have there Geo. Cell looks good too.

Rusty


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## jmdlcar

Geo said:


> ill start on this batch tonight it will take two cells and most of the night to complete it all.View attachment 2
> View attachment 1



How many grams were in those 5 bags? And how grams do you think your get?

Jack


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## Geo

those bags each contain 2 US pounds so there should be 10 pounds of pins. the bag on the top has some connectors ive never seen before so im not sure. ive been getting an ounce of gold from 6 pounds of these type pins so ounce and a half maybe ounce and three quarters would be nice.


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## nivrnb

Geo,

That is a lot of pins, and your cell is very impressive. I looks like you thought outside the box. Round cell just trying to be funny. What you have in pins, It took me very long to acquire a smilar pile. That is why I am in no hurry, I don't want to mess it up. I don't believe I will come accross this many pins again. So I am thinking if all goes well, start buying the plated jewlery and see how that goes. I hope all goes well tonight.

nivrnb


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## Geo

i was fortunate to know a man that owned a company years ago that made test equipment for the military. well the company went under in the early 90s and he stored all this old equipment at his home and a rented storage. i told him that i wanted to start some refining as i had about 500 pounds of computer boards and have tried over the years to harvest the gold without success. then one day while searching the net came across lazersteves website and thought "gee, that's simple enough for me to do" and followed a link to this forum. my friend said that if i split the gold with him i could scrap all the old equipment. i've been hauling and stripping components for three and a half months now.this stuff is unbelievably rich in gold and silver. and i still have all the computer boards i had originally and have been adding to it along the way as i can.


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## nivrnb

Just completed the anode, I think I may need to do this again. Just posting pics. I am getting off of my own subject of the copper mesh and am now going into the cell, I hope people don't mind. Please feel free to criticue, I have think skin. 8) I may have made the cathode to thick, from what I see of others.

nivrnb


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## nivrnb

Photos con't.


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## nivrnb

Photos Con't

Got the new Pyrex from Walmat. A little smaller than the original. Have to bend the anode tommorow pending comments. I folded the copper mesh in half, I hope that doesn't cause the amps to be high.

nivrnb


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## nivrnb

Power supply.


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## Geo

that cathode doesnt need to be free standing that way, it needs to be secured in some way because it could fall over during operation and cause a splash of hot sulfuric acid.


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## nivrnb

Geo,

Thanks, yes I am going to bend it today.

nivrnb


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## Amber

This is a really good thread. Please keep posting your process as I am at about the same level now. I've gotten a few questions answered, like having two (or more) copper baskets so you can rinse and let it dry while you start another basket.

Regarding the cathode - I'd like to share that I discovered a flat piece of lead in a friends shop. He explained that it was used to shim flashing into the mortar joints of a chimney before re-pointing the mortar. (Now most roofers just caulk it) I think this might be a great way to make the cathode, you just cut the shape you want and bend. I was rummaging around his scrap metal pile to find some kind of mold to make a cathode similar to lasersteve's. When I described what I was doing he handed me that! I'll bet you can still find it in real hardware stores. 

Here's a photo


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## nivrnb

Amber,

That is a great idea with the lead, please post your progress also. Interested on how your lead cathode works. I need to go back and correct my earlier posts. One of the questions I have about the cathode is that it has to be free of corrosion. So does this mean after the cathode is made, or after it goes into the acid, should I start preventing corrosion according to lazersteve? The first one I made was not even thru out, so I am in the process of making another one. 

Also from reading the posts, a smaller cell reacts the same way as a lager one, one of the benefits is that it uses less acid. A bigger cell can handle more material during a session. Philddreamer pointed out to me that a silver cell is constructed differently.


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## nivrnb

These photos are for a smaller cell that I will constructy first to get a sense of the smell, the time it takes to process.


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## Geo

you would use a copper cathode for a silver stripping cell. some types of material you would run in this type of cell are in the photos here that includes silver plated pins, flatware,jewelry and large peices of silver plated electronics. a thumb cell is used to refine the silver into fine silver crystals, i dont have photos of my cell and its out in the shop, ill post some later.


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## qst42know

Molten lead can be cast in wood a few times. The technique could save you some time constructing aluminum forms. You can get several copies before the wood is destroyed. It does smoke quite a bit though.


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## Amber

Thanks nivrnb for the invite to your thread.

Last night I read about making a basket and found some great tips and even a folding template. I borrowed an idea to take some copper wire to reinforce the basket. I also cut out the lead sheet to make the cathode. I am posting pictures and hoping for some input. I can add more wire to this basket. I think some kind of handle would help to lift and move it to a rinse tank. I can also trim the cathode if the amount of material is overkill for a small cell.

Let me know what you all think.


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## Geo

if you wear gloves you will not need a handle to remove the basket, just dont put your fingers in the rinse water if you have sulfuric acid on your gloves as it will heat up quickly. the cathode should be ok as is. if you run large amounts of pins at a time 1/4 pound or more it will pull more amps but you need a cathode with as much area facing the anode as you have anode area facing the cathode, if that makes any sense to you. :lol: watch your amps and if it goes over 10 amps it will cause your acid to heat quickly at 12 volts. you can use 6 volts to avoid the quick heat up but it will take longer to process.


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## philddreamer

nivrnb wrote:
" Philddreamer pointed out to me that a silver cell is constructed differently."
For silver crystals, yes. For de-plating, as I understand, is similar to the gold one. I haven't used the sulphuric cell for de-plating silver... yet! :mrgreen: 

I like Amber's lead strip for making the cathodes. That would simplify making one.


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## nivrnb

Amber,

Wow, that was quick, very nice cell, looks like you mean business.  We need to make this the show and tell thread. I like how you made the cathode very wide. Your copper mesh looks exactly like the plans posted, great job on that. I can't wait to hear peoples comments.

qst42know,

That is a great idea to make the mold out of wood, I am spending a lot of time on this cathode. Much more than is needed, but it is fun.

Geo,

Would love to see your silver cell, if you don't mind later can I send you a photo of some connectors to get you take on them to see if they are silver plated.

nivrnb


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## Geo

nivrnb said:


> Amber,
> 
> Wow, that was quick, very nice cell, looks like you mean business.  We need to make this the show and tell thread. I like how you made the cathode very wide. Your copper mesh looks exactly like the plans posted, great job on that. I can't wait to hear peoples comments.
> 
> qst42know,
> 
> That is a great idea to make the mold out of wood, I am spending a lot of time on this cathode. Much more than is needed, but it is fun.
> 
> Geo,
> 
> Would love to see your silver cell, if you don't mind later can I send you a photo of some connectors to get you take on them to see if they are silver plated.
> 
> nivrnb


sure, ill take a look.


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## philddreamer

When I made my lead cathode, I used an old frame from a pc, like Lazersteve.


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## Amber

nivrnb said:


> Amber,
> 
> Wow, that was quick, very nice cell, looks like you mean business.
> 
> nivrnb




Thanks. Quick I am not though. I have been reading and studying for months and since I found some free time due to hurricane Irene, I decided to fit the parts together today

I like the wood mold idea. Maybe you could use a router and make a shape to melt the piece you already have. Or I was wondering I lead is soft enough to hammer down what you have?


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## Geo

lazersteve sells the lead cathodes from his website for $6.00 apiece. www.goldrecovery.us username (gold) password (goldm1ner*) agree to the terms and click "shop"


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## philddreamer

Indeed Geo, & for the novice that's in need of equipment & "how to" information, he's a great source; he also has a number of videos. I bought from him the Fundamentals of Processing Pt/Pd & Silver Refining A to Z; they're excellent!
I also recommend a visit to his website!


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## Geo

actually the first lead cathode i made was poured into a clay mold. i had bought a twenty pound box of molding clay from hobbylobby for my son to make a school project over a year ago. it comes in a plastic bag inside a box and is still moist and soft today. i formed the mold on aluminum foil on a cookie sheet using the end of a 1x4 inch piece of plank and then hardened in the oven overnight on 250 degrees. i melted the lead in a steel can (canned corn i think :lol: ) and made three with that. i still have over 15 pounds of clay left.


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## nivrnb

nivrnb said:


> amber said:
> 
> 
> 
> Amber,
> I like the wood mold idea. Maybe you could use a router and make a shape to melt the piece you already have. Or I was wondering I lead is soft enough to hammer down what you have?
Click to expand...


I went to the recycle place today with the hopes that I could get lead like you have, but they were closed. I think I am going to go that way. I will still make the ones I have been working on and yes I would pound them flat. Hope all is well on the East Coast.

nivrnb


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## Amber

nivrnb said:


> Hope all is well on the East Coast.
> nivrnb



For our area not bad. We bought a generator and that meant we did not loose electricity. Anyone need a new Honda generator? :lol:

For sheets of lead, check with old roofers and contractors. According to my husband, it may be harder to find new than I thought. Maybe I got lucky looking in a fellow pack rats garage. I love the molding clay idea also. much easier to make the shape you want or event trim a bigger shape. For that matter, if you are melting a piece into the mold, a small flat square or rectangle would make your own sheet you can cut. Cutting was super easy. I bet an old bread pan would do.


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## jimdoc

We didn't lose power during the hurricane conditions yesterday, or even in the stronger wind gusts today. But tonight the power went out for a few hours when it was nice and calm as could be. 
Last week I felt the earthquake also, so this has been a weird week for this area.

I hope everyone in the hurricanes path made out OK as well. My brother stayed in his Absecon house a few miles from where it made landfall in New Jersey, and he had less wind and rain than us about a hundred miles from him.

We had a record amount of rain for any month in history in this area at over 13" for August before the storm. I think Irene added another 12" to that total. I was worried about the trees around my house because the ground is so saturated. 

Jim


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## butcher

Are you above the flood zone?


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## jimdoc

There is flooding all around near the creeks and rivers and down at the shore, but I am not that close to any water. Those people who live near creeks and rivers still have a few days until the water will go down. My yard is just very soggy from all the rain. Things could have been a lot worse.

Jim


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## nivrnb

Update,

Went to a recycler and they had some lead only $4.00 not bad, thanks Amber for the great ideal, my cell is moving along much quicker. Now, I just have to clean the lead, make extra screens. I also like the ideal of using a clay mold. Thanks again everyone for making this an enjoyable project.


nivrnb


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## Amber

That's a good lookin cell nivrnb

Looks like you are ready to run some scrap

Pleas keep taking those great photos. I am curious about the scrap you have and how it will work in the cell

I hope to start running my first batch next weekend.

Be safe

Amber


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## seawolf

Great photos, and from them I see a small problem. You will want to cut or raise the lead and basket so they will be higher in the cell or it will short out as the level of the gold powder rises. Let all of us know how things go.
Mark


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## philddreamer

Hi Nivrnb!
What type of material are you planning on running thru? 
To me, if you don't raise the side facing the cathode, & make more of a "basket", rather than a "narrow seat", you'll have a lot of material falling to the bottom & mixing with the gold sediment. Be aware that, @ times, you'll have to "stir" the material so to always have it make good contact for proper & thorough de-plating. 
IMHO, the porpouse of the basket is to be able to introduce more material & to keep that material, that is been processed, from falling & mixing with the gold sediment.

Take care! 
Phil


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## nivrnb

To all,

Thanks for the advice and comments, I’ve made some adjustments to the cell, I believe that placing items that have solder or lead on them will not have time to dissolve, I have items that have some white plastic in them, that need to come out before I place them in the cell. I don’t want to gunk it up with plastic.

As far as the cooling of the cell I have an idea of using those reusable gel packs you place in the freezer to place under and around the cell, haven’t gotten to that point yet. 

nivrnb


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## nivrnb

con't


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## Geo

theres a good chance that the plating extends underneath the plastic, it would be better if you could remove it but its not necessary.


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## qst42know

It's not necessary in an aluminum mold for lead but a coat of soot improves the casting of low temp metals as well.


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## nivrnb

All, 

Power supply for the smaller cell will be a 13.6 V, 6 A regulated. On the other thread Steve was calling for a 

"In short the generic terms like cold, hot, and 12 v 10 A battery charger are more than accurate enough to get a cell operational and producing gold. If you need a more accurate assessment of the temperatures, then let me suggest these operating conditions for the hobbyist cell set up:"

It is getting close to lift off on the cell, I will use the smaller cell and after I have done a few pieces to see how it goes, will see I think I’m ready but will spend more time reading the great article on the other thread “Pic of my cell”.

nivrnb


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## Geo

i have alot of the same type of scrap and some of the longer connectors with plastic in the middle will snap apart in places and just push the plastic out. the square 'RF" connectors however is still a thorn in my side, ive taken a dremmel and cut one in half and the plating is all the way through BUT cutting each one is like skinning a bee for its wax. alot of effort for a little return. im running them as is but keeping them for later processing as soon as i figure out a way to get inside without all the effort. the power supply you have is ok but you can add a amp meter on the positive side. i like watching the amps because when the material is almost done it may not show bubbles on the surface but if its still pulling amps there is still gold present being stripped. amp meters are cheap and easy to add, it has two connectors. the positive side goes to one connector and the other connector goes to the cell.


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## nivrnb

Update,

Geo, I have an amp clamp I am going to use with the power supply. I have to modify the the mesh, it should be low in the front. So I will just cut away the front of the mesh.

nivrnb


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## qst42know

I think your anode and cathode are far to close together. I expect you will be running high amps and overheat very quickly.


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## nivrnb

qst42know,

Thank you for the heads up, I will shorten the baskets, I can feel myself getting anxious about running the cell. 

nivrnb


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## zenophryk

This is my first post, after much lurking and reading and oogling.

I decided my first project should be a cell. The construction is fairly simple, and I have all the materials. Instead of a basket made with mesh, I'm going to try some sheet copper, bent into a basketish form with maybe some holes on the bottom to help drain. Has anyone done that with any success?

I also want to come up with a clip to allow me to deplate fingers. Everyone says a cell is no good for fingers, likely because of the electrical connection needed on each one of the fingers. So I'm thinking about trying to make a wide clip that will make contact with a the front and back of the fingers, and at least maybe 2 inches wide. has anyone tried that yet?

So there is a whole lot posted on the how to build a cell, and run a cell. but I havn't seen too much in a step by step for what to do when you're done.
How do I know when to stop, how do I proceed afterwards?

-Zenopryk


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## Palladium

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=8543&hilit=stripping+cell+clean+up

http://goldrefiningforum.com/phpBB3/search.php?st=0&sk=t&sd=d&sr=posts&keywords=stripping+cell+clean+up


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## dvdczar

hello all , 
im new to the forum and a noob to your processes but while studying this cell and others heat seems to be a problem for you. Is it possible that instead of a water or ice bath which appears to be dangerous by what ive read, use a heat sink somewhat like whats used in beer making but form the heat sink from copper tubing and make it double as the framework for the mesh and a handle , attach rubber tubing so as to make the basket more easy to handle then to the cold water faucet with another hose back to the drain, its also possible to instead use a recirculating pump and a water chiller but thats more expense. anyway with what im learning here in the forum id just like to make any contribution i can


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## Geo

the reaction of concentrated sulfuric on copper is very slow but it still reacts especially as the temperature rises among other factors.copper tubing is a poor barrier to use between concentrated sulfuric acid and water as the tubing will eventually fail.water when introduced to concentrated sulfuric will not mix immediately and droplets will settle to the bottom and then react with the acid,the result is it will flash boil and the steam explosion will blow hot sulfuric acid every where.its a nice concept and the thought process looks good but i would advise not using copper tubing filled with water in a sulfuric stripping cell.


----------



## Amber

zenophryk said:


> This is my first post, after much lurking and reading and oogling.
> 
> So there is a whole lot posted on the how to build a cell, and run a cell. but I havn't seen too much in a step by step for what to do when you're done.
> How do I know when to stop, how do I proceed afterwards?
> 
> -Zenopryk



Hello,
There are a few good threads about processing. Look around some more, I wouldn't want to state something from memory inaccurately. I keep notes on the threads I find that apply to the processes I want to try. I did find a post that indicated running the cell for 24 hours or less then process. Another bench mark is a given amount of grams of gold in the cell.

I did want to share that I decided to weigh each batch before I process it and after. My hope is this will give me a good estimation on what is in the cell. This number will be useful when the batch is ready to go to AR. It will help to use close to the right amount of nitric acid in the AR. Excess nitric is undesirable when you want to drop the gold out of solution.

A second tip I have to share: I am running GP jewelry and was advised to check for silver under some of the vintage stuff. Great advice. I didn't find any silver, but I found two pieces that were 14KT. They weren't marked, so I had them in the scrap pile to de-plate. When they came out still gold, I figured they had bad contact and I put them in again. Still shiny gold? Hmmm, the cell didn't work on the karat pieces and I tested with acid to confirm. Now they are in the correct jar.

Bests,
Amber


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## Geo

Amber said:


> I did want to share that I decided to weigh each batch before I process it and after. My hope is this will give me a good estimation on what is in the cell. This number will be useful when the batch is ready to go to AR. It will help to use close to the right amount of nitric acid in the AR. Excess nitric is undesirable when you want to drop the gold out of solution.



the only flaw to this that i can see is not just gold that is stripped but also nickle and some other substrates even copper.if you weigh a batch and process and then weigh the waste metal you may have a proximate weight of metal in the cell but not necessarily the amount of gold. given the fact that mill spec can be different for the exact same piece from part to part according to the costumers needs without an X-ray machine to test thickness of gold plate theres really no way of knowing how much gold can be in any one batch.this poses no big problem for what you have described unless you make your AR before the process.a better way of using AR for something like this is to add the prescribed amount of hcl and add nitric in small increments as needed untill all the metal is dissolved.and as a side note heat the hcl before you start adding the nitric to ensure the reaction has run its coarse before adding more nitric.


----------



## Amber

Thanks Geo. I was unaware of your tip to heat the hcl before adding nitric. I will do that. Do you add the nitric while it is still hot, or do you let it cool again?

Yes the weight is an approximate. I had no idea where to start and I read some of the spread sheets for calculating plated material. I found estimating surface area and plating thickness to be beyond practical. So I thought the difference between "weight in" and "out" as a simple starting point. I also figure there will be losses. As careful as I rinse, I think not every drop is staying where I would like it. I plan on keeping the records through the end. With each batch I process, the numbers will have more meaning when I can tie it to a button of a given size as the result.

I have only started putting it all together and I really appreciate all the comments along the way to make sure I don't spend too much time down the wrong path. If I hadn't found this forum, I would not have tried the cell.


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## Geo

add the nitric to warm solution SLOWLY in small increments.the warmer the solution the more vigorous the reaction will be.you don't want a run away reaction and a possible boil over.cool solution may show a slight reaction on the addition of nitric and make you think you need to add more and before you know it you have added too much.warm solution tends to have the reaction happen faster and more instantaneous.if you are watching over the reaction you will see a definite start to the reaction and a definite end of the reaction (relatively speaking).look after each reaction and make sure theres still metal to be dissolved before adding more nitric.


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## Manoel

Please

I am a newbie and I am trying to understand how this electrical process works... however, I have a question... how to filter/extract the gold from you acid solution ?

Sorry for this newbie question!

Regards!
Manoel



Geo said:


> add the nitric to warm solution SLOWLY in small increments.the warmer the solution the more vigorous the reaction will be.you don't want a run away reaction and a possible boil over.cool solution may show a slight reaction on the addition of nitric and make you think you need to add more and before you know it you have added too much.warm solution tends to have the reaction happen faster and more instantaneous.if you are watching over the reaction you will see a definite start to the reaction and a definite end of the reaction (relatively speaking).look after each reaction and make sure theres still metal to be dissolved before adding more nitric.


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## nivrnb

Manoel,

Here is some info form Philddreamer on another post. : ) nivrnb

Re: my first button


lazersteve said:


> "Black Powder from Cell
> 
> When your cell is full you should:
> 1. Let all the black powder settle
> 2. Pour off the bulk of the concentrated sulfuric acid. Don't worry about the small amount of residual black powder that is in the acid that is poured off as you can get it on the next batch.
> 3. The remaining acid with the bulk of the black powder in it should be slowly added (let it cool before adding more) to five or six times it's volume of water.
> 4. Stir this very well and allow to settle again.
> 5. Siphon off the colored solution. Repeat this process until the wash is no longer colored.
> 6. Test a few drops of the rinse water with a drop or two of 3% unscented clear household ammonia, if the rinse water turns blue when the ammonium hydroxide is added, copper is still present and more rinsing is required.
> 
> 7. Dissolve the black powder with AR or HCl-Cl and proceed as typical for these processes.
> The concentrated acid that was poured off is used in your next cell run as is. Hot concentrated acid is very dangerous, so exercise extreme caution when handling it. Never add water to concentrated sulfuric acid/powder mixture, add the acid/powder slowly to the water instead.
> Steve"


Daveedo, the information is here. Check it out.

viewtopic.php?f=38&t=9473&p=109846&hilit=sulphuric+cell#p108380

Phil


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## philddreamer

That information was posted by Lazersteve & I saved it & use it when I run my sulphuric cell. I shared it with Daveedo de other day.

Niv, you did good sharing it with Manoel!

Manoel, take care & be safe!

Phil


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## nivrnb

Phil,

Thanks for the comment! I have been reading about posting video's from Noxx and wanted to repost this video of a cell in action from youtube. I beleive metalicmario posted this and just wanted to give them props.

[youtube]http://www.youtube.com/watch?v=cCro6V_RsTo&feature=related[/youtube]


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## philddreamer

Niv, if I'm not mistaken, "metalicmario" is "goldenchild" in our forum.
Thanks for sharing Niv.

Nice video Mario! 8) 

Phil


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## Bissel9

can anyone tell me the chemical mixture used in a sulfuric cell?


----------



## Harold_V

Bissel9 said:


> can anyone tell me the chemical mixture used in a sulfuric cell?


Simple. Concentrated sulfuric acid. Nothing more.

Harold


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## Marcel

Anyone gathered some data on yield so far?


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## artart47

Hi!
Just here educating myself for the day when I'll want to build a cell for my stuff.
I read the part about finding a cover and using plastic wrap....Had an idea! If you choose to use an ice bath, why not put the whole cell in a larger container with the ice covered and sealed with plastic wrap to seperate the H2O from any acid spil? If the wrap was loosely fitted,real baggy, it would follow the shape of the cell and tranferr the heat to the ice water and would hang down to the workbench on all sides and give protection fron water/acid contact.

artart47


----------



## Geo

artart47 said:


> Hi!
> Just here educating myself for the day when I'll want to build a cell for my stuff.
> I read the part about finding a cover and using plastic wrap....Had an idea! If you choose to use an ice bath, why not put the whole cell in a larger container with the ice covered and sealed with plastic wrap to seperate the H2O from any acid spil? If the wrap was loosely fitted,real baggy, it would follow the shape of the cell and tranferr the heat to the ice water and would hang down to the workbench on all sides and give protection fron water/acid contact.
> 
> artart47




no one here will advise you to have water anywhere around concentrated sulfuric acid. members have dabbled in other ways of cooling the solution without using water. it is difficult when typing to express how dangerous this is, one slip or trip or fumble and you can be horribly scarred or even blinded with no second chances.


----------



## Harold_V

Geo said:


> no one here will advise you to have water anywhere around concentrated sulfuric acid..


For the record----I was flown to New Mexico back in '75, by a customer that had done research on sulfuric stripping cells and wanted me to build one for him. The government was engaged in stripping surplus items, and had recovered something like 35,000 ounces of gold the previous year. The yard at the military installation was filled with drums of stripped items. 

The cell in use was made of mild steel, and had a water cooled jacket. They had 300 amp capabilities, so heating was a serious issue. To my knowledge, there were no issues with the water being present. There was no mention made, at any rate. Bottom line is---water can be used---but it should be used wisely. Your points can be valid. 

Harold


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## Marcel

If I had to set up a very large cell, I would use a cooleant that does not contain water. Oil or glycerin f.i. (whereby I dont know if those substances are reactice to concentrated sulphuric acid). Just an example - how to avoid any possible problems with minimal effort.
Just makes no sense, if there is a million other ways to do it and you do have the budget to do it right.
And increasing the surface of a system would also be one of the first measures or adding heatexchangers. The cell that is shown here is just the minimal principle. There is so much you can do if you construct a whole plant, no need for me to use any water.


----------



## The Refiner49er

I am about to construct a moderate size sulfuric cell for recovering values from GF watchbands and various other materials that is impractical to process in nitric acid. I have read many of the threads on this subject, and basically want to avoid using copper mesh for the basket(s) due to the relatively high cost, and it is also considerably hard (impossible) to find locally. Can someone please recommend an alternative metal, perhaps a certain grade of SS that will still work acceptably?

Thank you!


----------



## butcher

I think Laser Steve may have copper mesh on his web site store, have you checked?
I think I would stick with method recommended, at least until I had that method working and understood it well, before trying something different, that way I would know if my change was effecting the results of the outcome.


----------



## AztekShine

Awesome thread! :mrgreen:


----------



## jimdoc

The Refiner49er said:


> I am about to construct a moderate size sulfuric cell for recovering values from GF watchbands and various other materials that is impractical to process in nitric acid. I have read many of the threads on this subject, and basically want to avoid using copper mesh for the basket(s) due to the relatively high cost, and it is also considerably hard (impossible) to find locally. Can someone please recommend an alternative metal, perhaps a certain grade of SS that will still work acceptably?
> Thank you!




I found copper mesh in AC Moore art supply stores for around $10. Plus they always have 40% or 50% off coupons in the paper at least once a month.

Jim


----------



## goldsilverpro

The Refiner49er said:


> I am about to construct a moderate size sulfuric cell for recovering values from GF watchbands and various other materials that is impractical to process in nitric acid. I have read many of the threads on this subject, and basically want to avoid using copper mesh for the basket(s) due to the relatively high cost, and it is also considerably hard (impossible) to find locally. Can someone please recommend an alternative metal, perhaps a certain grade of SS that will still work acceptably?
> 
> Thank you!



Has anyone had luck (good and bad) stripping gold filled with the sulfuric stripper? Can you relate your experiences? For example: 10K vs 14K? 1/10 vs 1/20? How long did it take?

I've never liked the idea of metal anode baskets. From my experience, I've always thought they set up sort of a Faraday Cage, inhibiting current flow on the inside. Also, I hate the idea of the parts just sitting there, shielding the inside of the pile from getting much current. One of these days, I'm going to gather the stuff needed to make a small cheap perforated (try to get at least 50% openings) plastic rotating tumbler with a center rod (axle) contact. If doesn't necessarily need a motor - just hand crank it often to change the position of the parts you're stripping. Much faster and more efficient than a stationary metal basket. It doesn't sound that difficult.
http://en.wikipedia.org/wiki/Faraday_cage


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## stihl88

Someone posted this a while back now but it's basically what your referring to GSP.


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## The Refiner49er

Thanks Stihl-

Hey could you post the link to this thread or otherwise the title so I can read the text comments and info? Looks like this rotary basket works great!

Still hoping to get feedback on other people's GF experiences (clearly GF NOT meant as "Girl Friend", LOL!) using a stripping cell, and any problems/solutions that may have been discovered. 

John


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## stihl88

Here it it http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=5092&hilit=sulfuric+tumbler


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## lazersteve

Gold Filled is not well suited to the stripping cell.

The results of my testing are that the part will continually fizz and never actually finish stripping. When I sit back and thought of a reason for this I came to the conclusion that the way gold filled is manufactured is the cause. The outer layer of a gold filled item is actually a layer of karat gold physically layered (not plated) over the base metal under layer. For this reason the gold filled scrap behaves exactly as karat gold in the cell. 

You get a lot of fizzing, a lot of heating, a little stripping, and a dull yellow metal as the final result. This dull yelllow metal still contains gold.

Steve


----------



## Harold_V

lazersteve said:


> Gold Filled is not well suited to the stripping cell.
> 
> The results of my testing are that the part will continually fizz and never actually finish stripping. When I sit back and thought of a reason for this I came to the conclusion that the way gold filled is manufactured is the cause. The outer layer of a gold filled item is actually a layer of karat gold physically layered (not plated) over the base metal under layer. For this reason the gold filled scrap behaves exactly as karat gold in the cell.
> 
> You get a lot of fizzing, a lot of heating, a little stripping, and a dull yellow metal as the final result. This dull yelllow metal still contains gold.
> 
> Steve


It is my opinion that gold filled doesn't respond to stripping for the same reason that copper is an excellent material for the baskets. 
As you alluded, Steve, gold filled is made exactly as you proposed. A layer of gold alloy is applied to base metal, which is then rolled to a specific thickness, from which parts are made. 

Harold


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## qst42know

I would assume the rolling to desired thickness results in a high degree of blending at the bond boundary?

Steve, was any of the gold filled you ran stainless as in watch band tops or was it copper base metals?

Come to think of it I haven't cut into a stainless top to look for a copper bonding layer.


----------



## g_axelsson

qst42know said:


> I think your anode and cathode are far to close together. I expect you will be running high amps and overheat very quickly.


Speaking as a physicist and not with experience from the cell (that project is still in the future).
The closer the distance between the electrodes the less heating it will cause for the same amount of gold produced.

The heating in the cell comes from two different sources, one is chemical energy, gold dissolving and precipitating. This we cannot do anything about so it will be constant in any case... so I'll just ignore that part.
The second source is resistive heating, current moving through a conductor (our electrolyte, sulfuric acid). As the distance increases the resistance also increases and if we kept the current constant we would get more heating. (mathematically speaking, P = U*I = I2*R, I2 constant and R increasing leads to P increasing )

I suggest trying to keep the distance between the anode and cathode as short as possible without short circuit it. I guess that there is a practical minimum distance too as we don't want our cathode in the boundary layer where the gold still is in solution.
Then lower the voltage to keep the current down to a reasonable level.

If you can't lower the voltage just put a light bulb in series with the cell, for example a 12V 50W bulb will give a maximum of 4A current.

I would like to try this but first I have to try and master the classical design.

Göran


----------



## Geo

g_axelsson, for some reason im not sure of, the closer the anode and cathode are to one another builds heat faster (or at least it does in my cell). i have a theory about it. i believe that the closer the two are to one another, the more vigorous the action becomes.


----------



## bswartzwelder

Geo,
I would think the closer the anode and cathode are to each other, the lower the resistance between them. Lower resistance means higher current flow and the power through the cell goes up.


----------



## Geo

bswartzwelder said:


> Geo,
> I would think the closer the anode and cathode are to each other, the lower the resistance between them. Lower resistance means higher current flow and the power through the cell goes up.



exactly, thats why im not sure for the reasons behind it. the only thing i can come up with is due to the increased activity at the anode.


----------



## g_axelsson

Geo said:


> bswartzwelder said:
> 
> 
> 
> Geo,
> I would think the closer the anode and cathode are to each other, the lower the resistance between them. Lower resistance means higher current flow and the power through the cell goes up.
> 
> 
> 
> 
> exactly, thats why im not sure for the reasons behind it. the only thing i can come up with is due to the increased activity at the anode.
Click to expand...

That's why I suggested to lower the voltage to keep the current at the same level. It is the current that is deplating, not the voltage. The voltage is only forcing the current through the cell.

12V is a hughe voltage for an electrolytic cell, you can split water into oxygen and hydrogen with as little as 1.23V, the extra voltage is lost pressing the current across the gap between the electrodes.

Lets analyse a theoretical situation ( as one of my heros used to say, a gedankenexperiment ) 8) 
Say that I have a cell with 2 cm between electrodes, it has a resistance of 4 ohm in the electrolyte and I can deplate my material in one hour...


Code:


I = 12V / 4 ohm = 3A
P = 12V * 3A = 36 watt
W = P * 1 hour = 36 watt hour

If I now move the electrodes to sit on only 1 cm distance I have also cut down the resistance to half, 2 ohm.
The new cell would get these numbers...


Code:


I = 12V / 2 ohm = 6A
P = 12V * 6A = 72 watt
... but the higher current means that we now deplate in half the time
W = P * 0.5 hour = 36 watt hour

Now drop the voltage to half too
The new cell would get these numbers...


Code:


I = 6V / 2 ohm = 3A
P = 6V * 3A = 18 watt
... but with the lower current means that we now are back at deplating in one hour
W = P * 1 hour = 18 watt hour

So by cutting down the voltage and moving the electrodes closer we can deplate with the same speed but half the effect, ie with half the heating.

This is a bit simplified as I haven't calculated any electrode potentials, electrode polarization and a number of factors that I don't know about as I'm no expert on electrolytic cells.

If you can't lower the voltage then I suggest adding a lightbulb in series as that can be considered as a constant current device. The excess voltage will burn off as heat in the lamp, not in your cell.

Göran


----------



## bswartzwelder

Goran,
I really like your explanations and you're right on the target, as usual. Power companies transmit huge amounts of power over very long distances. To keep their costs and losses to a minimum, they raise the voltage (very simple with a step up transformer) and the current drops (almost in accordance with ohms law). When I worked for a power company, the output from one of their generators was somewhere around 25,000 volts and the current in the neighborhood of 30,000 amps. The "wires" (huge buss bars actually) coming out of the generator were massive and the power was transmitted from Southern Maryland (Lusby) to Waugh Chapel (also in Maryland) for a distance of approximately 52 miles. To put up buss bars between these two locations would have probably cost billions of dollars. Once the power was outside the turbine building, it went to a switchyard where the voltage was increased by a factor of 20 to 500,000 volts. The corresponding current dropped by a factor of 20 to 1500 amps. Much easier to send over long distances. Not to mention, a drop in voltage of 1000 volts between beginning and end would have a very low amount of loss as compared to a 1000 volt drop on the original 25,000 volts.

Along the lines of this thread, many places it has been said to use an automotive type battery charger with at least a 10 amp output. For the most part, these chargers are unregulated and variations in the load can (and do) cause variations in the output of the charger. A truly regulated power supply (like a lab power supply) although expensive, is a very easy way to regulate the electrolytic cell. You can dial up whatever voltage you want and set the maximum current to any value the power supply is capable of outputting. If you want to go the route of adding light bulbs in series with the cell, you can easily get almost any current you want simply by adding more light in parallel with each other. I would recommend using automotive type lamps and soldering wires on them as getting sockets may be difficult to obtain. To determine the output current, connect your lamp(s) into the dry circuit (no acid in the cell), then short the anode to the cathode. Read the current. That is the absolute maximum current your cell could draw while in operation, even if a short occurs between the anode and cathode. To get more current, use a higher wattage rated light bulb or connect two (or three) in parallel. Like Poormans AR, this is a Poormans regulator. By the way, the light bulb idea has an added benefit of limiting the short circuit current in the event no one is watching as the short happens. It could save you from destroying your battery charger or even worse. For a few dollars, anyone can purchase a DC ammeter and connect it anywhere in the cell circuit. I have connected them on the negative side of the circuit at times when I wanted the total current in the circuit or on a single leg of a circuit on the positive side to look for problems in that circuit. If the meter pegs backwards when power is applied, just reverse the leads on the back of the meter.


----------



## butcher

Very good information from g_axelsson, and bswartzwelder, I would like to add a little bit more light on this subject if I can, on the use of the DC lamp in series with your cell.

The lamps filament is a coil of wire, and when wired in series with your cell is just like part of your wire to the electrode of your cell, the current just passing through your wire and then through the lamps coil on its way to your cell, the lamps filament has a certain resistance, this resistance also changes with temperature.

This resistance regulates the current through the lamp and also through your cell, because they are in series the current is the same through the cell and the lamp ,and the voltage divides between the lamp and the cell, depending on their individual resistance.

The lamps resistance changes with the filament temperature, a cold lamps filament has a low resistance (dim light bulb), as the filament temperature rises (brighter light)the resistance also changes the hot lamp resistance increases to a higher value, this being in series with your cell keeps the current constant in your cell.

Actually it is your cells resistance which changes with differing conditions in the cell, so the cells resistance changes conditions of this total circuit, and this in turn changes how bright the lamps filament will be (and its temperature, or resistance).

So the lamp acts as a current regulator, keeping the current at a constant value through the cell, even as the cells resistance changes.

The lamps brightness is also a good visual indicator of the cells resistance and what is happening inside your cell, as well as a being a current limiter which can protect your power supply, as the lamp would have a maximum current it could pass.

The current through the lamp and your cell is dependent on the conditions of your cell (cells resistance), these being in series, the current is the same through both the lamp and the cell, but the voltage divides between the lamp and the cell.

The lamps filament resistance will drop some voltage to the cell, depending on the lamps filament temperature, (this will depend mainly on your cells resistance how bright or dim the lamp is),
if the cell is shorted (cell no resistance, or low resistance to current) the cell would drop no voltage, and the lamp would be taking the full voltage of the power supply (lamp glowing bright), with the lamp temperature high it becomes a bigger resistance to current and thus drops more of the voltage.

If the cells resistance was high the cell would drop more voltage and the lamp would run cooler and dimmer, with the lamp using up much less of the voltage from the power supply, and the cell using up that voltage.

So the lamp is regulating current to a constant value through your cell, with the lamp acting as a variable resistor, changing resistance with temperature, and the lamps temperature is actually changing because of your cells resistance, although the voltage in both the cell and lamp vary, as they share the total voltage of your power supply between them.

How much current will depend on the lamp will use up, a cool filament (dim light) will pass a higher current (less resistance in the lamps wire coil), a hot filament will become a greater resistance to current the filament also acts as a heater, heating up, and using up (or burning up) current as heat, when you choose a light bulb, choose one for the maximum current you wish to have in your cell.

A lamps resistance can change from 5 to 10 times the resistance depending on the filaments temperature, the hot filaments resistance can be 5 to ten time higher than the cold filaments resistance, as an example a 40 watt lamp (120 volt AC) has a cold resistance of around 28 Ohm's, but when hot has a resistance of about 360 OHM.

The lamp acts as a current regulator, keeping the current constant in the cell, it does this through taking the voltage of the circuit the cell does not use, the voltage of the cell varies with its resistance, the lamp also acts as a visual indicator (like your ammeter), giving you a visual indicator as to what is happening in your cell, it can also add light to your lab on dark nights :lol: .


----------



## Harold_V

I'm a little late to this party, and may have interpreted the topic incorrectly, but if I have not, one thing you guys should keep in mind is that the way a sulfuric cell works isn't exactly as you imagine. While current is a function of the end result, it is not the current (or voltage) that strips the values---it's the persulfuric acid that is developed in the proximity of the anode (the items being stripped) that removes the values. The current is involved to the exent that it is what creates the persulfuric acid, which occurs only in the close proximity of the anode. As the now dissolved values leave the anode, the lack of the required amperage causes the persulfuric acid to revert back to sulfuric acid, which is not capable of holding the values in solution, so they precipitate as the fine black smut that is common to the sulfuric stripping cell. 

Temperature is critical in order to prevent the cell from dissolving base metals. Large cells are temperature controlled (via a water jacket), so they can operate continually. 

Harold


----------



## g_axelsson

Harold_V said:


> it's the persulfuric acid that is developed in the proximity of the anode (the items being stripped) that removes the values. The current is involved to the exent that it is what creates the persulfuric acid, which occurs only in the close proximity of the anode.


Not that I doubt you, this is the description I read a number of times. But if that is the case, how come that the current drops off when the gold is stripped? Shouldn't it continue producing persulfuric acid even when the gold is gone?
Maybe a boundary layer with persulfuric acid is created that stops further action? 

Göran


----------



## Geo

i think its a reaction to the gold metal in particular.


----------



## NobleMetalWorks

A sulfuric stripping cell works like this:

Persulfuric acid is created at the anode which attacks and dissolves gold, as soon as the gold ions go into solution the persulfuric acid changes back to sulfuric acid which cannot hold the gold ion in solution, so the gold precipitates out of solution as the fine gold sand/dust/mud whatever you want to call it. Persulfuric acid only exists in close proximity to the anode just exactly as Harold has stated.



g_axelsson said:


> Harold_V said:
> 
> 
> 
> it's the persulfuric acid that is developed in the proximity of the anode (the items being stripped) that removes the values. The current is involved to the exent that it is what creates the persulfuric acid, which occurs only in the close proximity of the anode.
> 
> 
> 
> Not that I doubt you, this is the description I read a number of times. But if that is the case, how come that the current drops off when the gold is stripped? Shouldn't it continue producing persulfuric acid even when the gold is gone?
> Maybe a boundary layer with persulfuric acid is created that stops further action?
> 
> Göran
Click to expand...


Gold is highly resistant to oxidation, but base metals are not, they will readily oxidize. As soon as the gold is deplated, it exposes the base metals to the persulfuric acid which causes the base metal to produce a protective oxidized layer, which is the reason you see a drop in voltage.

Matter of fact, this oxidized layer works so well at protecting the base metals from being attacked, that material under that does have gold plated on it still, will have to be re-arranged so that current can be applied again and the gold plating can be removed from the rest of the material.

This is also the reason why you don't want to overload your anode basket because the very top layer of your material will oxidize as soon as the gold is deplated, and protect the material underneath with gold plating from being attacked by the personfulric acid. If you have operated a sulfuric cell for any length of time, you will notice the top layer of material strips and turns a greyish color, this is a result of oxidation.

If you put too much material in your anode basket, and then re-arrange the oxidized layer with the material that still has gold plating, you end up with oxidized material that can still prevent the gold plated material from being attacked by the persulfuric acid. Gold plated jewelry or large gold plated items deplate easier than do gold plated pins.

Scott


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## g_axelsson

Thanks for the long explanation Scott. I still think that we have a rather crude and not totally correct description of how the sulphuric cell is working. When I make my own cell I will do some experiments to see if my hunch is correct.

The explanation with the oxide layer could explain why the current drops off. As far as I have read, there is no need for gold in making persulfuric acid via electrolysis of concentrated sulfuric acid. In a text I found they mentioned platinum electrodes. Also that iridium electrodes dissolves faster than platinum electrodes. The common thing here is that none of these electrodes oxidizes.

Interesting read : Per-acids and their salts (1912)

Göran


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## NobleMetalWorks

I believe Geo was eluding to the fact that the current only reacts with the sulfuric acid to create persulfuric acid, in the immediate area of the anode so long as there is gold to be dissolved, but that when the reaction with the gold can go no further because there is no more gold to be attacked by the persulfuric acid, the base metals oxidize and prevent the electrical current from making any more persulfuric acid, and thus the voltage drops to zero.

I think this thread has done a fair job at explaining what exactly happens, and why, in a sulfuric stripping cell. It's a well known processes that has been used to good effect since the 1940s. I don't really think further experimenting will produce any deeper understanding unless done solely for your own personal observation to become more visually familiar with how the process works.

A book I would recommend reading in regards to electrochemistry is titled "Industrial Electrochemistry" I own the second edition, I am not sure if there is a third or fourth. The authors are Derek Pletcher and Frank C. Walsh and published by Chapman and Hall. My copy was printed in 1990.

http://www.amazon.com/Industrial-Electrochemistry-Derek-Pletcher/dp/0412165007

Scott


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## bswartzwelder

This thread has, for me, become one of the most interesting reads in quite some time. The depth of the explanations into what is actually happening are quite detailed and yet, as always easy for the new person to the forum to grasp and understand. A huge thank you to all. 

A couple of things to consider when using the light bulb in series between your cell and the power supply. 1. The new LED type lamps WILL NOT WORK. They are polarity sensitive meaning they have to be connected the right way, and they only allow a very tiny amount of current to pass. Not enough to operate your cell. 2. The bulb you do use can be critical. A type 194 bulb (used to light the instrument cluster) at full brightness normally takes 0.27 amps (not enough to operate an electrolytic cell.). The LED version of the same light draws 0.07 amps. A type 3157 lamp has two filaments, smaller one (current draw) for parking lights and larger one for turn signals. At full brightness, they draw 0.59 amps and 2.1 amps. A 5006 halogen sealed beam headlight draws 2.73 amps at full current draw. It provides what appears to be much more light than the 3157, but it is a halogen light meaning it runs much hotter and the light is concentrated by the internal reflector. Sockets for these lamps are readily available at most good auto parts stores. Also, be careful to make sure the lamp is supported or sitting on something non combustible. While they are on, (especially halogen lamps) they can produce burns to the skin. If you accidentally spill a liquid on them, they can shatter exposing a white hot filament which could ignite a fire.

When you start operating your cell, initially, the lamp(s) should come on but be dim. If they go to full brightness, there is most likely a short circuit in your cell. As the gold de-plates, the lamps will become dimmer and dimmer until they appear to be out completely. Be careful here, because there could be a problem with your circuit, or if everything is working, there could still be voltage present. A standard 12 volt battery charger will not shock you (even if you hold one battery clip in each hand) unless your hands are wet or have something on them like sweat or a weak acid. But, it is always a good practice to treat every electrical circuit with respect. I remember as a kid, I would touch the contact tips of a standard 9 volt battery for transistor radios on the tip of my tongue to see if it was dead. TRUST ME, you would know there is voltage present. Since that time, I have heard of one individual dying by putting a 9 volt battery in his mouth between his upper and lower teeth. Supposedly, he could not open his mouth because the battery caused the jaw muscles to clamp shut and then the current flow circulated through his brain from the upper jaw to the lower jaw. I have never seen any proof that this ever happened, but why take the chance. Have also heard that it takes less than 1 milliamp to stop your heart. I won't be testing that theory anytime soon.

As I mentioned elsewhere, no matter what lamp you pick, if it doesn't allow enough current for your cell, you can parallel more lamps until you do get the desired current flow through your cell.


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