Large Gold Stripping Cell -2lbs at a time.

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I

Ignatz61

Well-known member
Joined
Jan 2, 2008
Messages
108
Location
NY
Here are the pictures I promised. Sorry it took so long. This HCL/CL problem has tied me up for a while.

The black PVC is Black from use.I ran it all night and some gold burned into the plastic.

The insert is Perforated PVC pipe with Copper foil rolled up as a liner. This helps solves the "intimate contact" problem. I am experimenting with different Stainless Steel ( welding Rod) insert electrodes for maximum electrical contact. Once I started using the copper foil the electrode design dosen't seem to matter as much.
The 4" pipe on the wall hanger has a valve at the bottom. Once stripping is done I take out the insert
Place it in a bucket, remove the SS bottom slide and push everything out of the insert into the bucket, Flush with water (carefull this makes lots of fumes untill acid residue is diluted enough.)
Meantime I have another insert preped and drop that one in while I am washing the first.
I add a little acid to replace what comes out with the insert. After settling I open the valve at the bottom and the bulk of the gold sludge drains out.
When the thick sludge bcomes thin I close the valve and add acid, It is ready for the next job.

The long lead anode hangs inside the cell with a lip for the alligator clip to attach to.
Positive alligator clip I clip onto the SS wire insert.
JOHN
 

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the copper holds up for a long time, I had 1 piece thin out on me but I had a full load going all night at 6V 2 amps. (I turn down the amps if I have to leave it for a while) . In the morning it was still striping quite well so I left it all day while I was at work. By the time I pulled the insert the copper had thinned quite a bit. So I know there will copper to deal with in this batch.
Also it turned th insert Black. Normally this washes right off when you unload the insert but this is baked in. So I will use it and eventually soak it in AR or cut it up and melt it a little at a time.
The foil helps keep in small pins. I made one with tiny holes hoping to keep pin from going through, but this was a real pain to get all the gold powder out of the holes.

My original plan had another valve at the bottom of the clear tube. This way I could run the cell with the top valve open and the bottom closed. when I could see the tube was almost full of black powder I would close the top valve open the bottom valve and drain the bulk of the sludge with a minimal amount of acid to be diluted. This cuts down on the amount of liquid to be handled and helps speed things up.

Problem was the valve at the bottom was grey plastic not white PVC and the first time I used it the acid ate the guts right out.
It works well with just the one valve, I open it until I see the liquid thin out and then close it. Still concentrates the sludge nicely leaving the bulk of acid still in process.
Also the clear tube gets black and you can't see when its full anyway.
A larger collection jar connected to it might be good, then you could let things settle with the valve open. Close it empty the jar, reconnect and open the valve. Add a jar's worth fresh acid and your back in business!
 
At first, I was confused because you used the term, "lead anode". It seems to me that the lead is the cathode.

In the photos, it looks like the parts will be inside of the copper foil. If so, I would think that the current would primarily be applied to the copper and very little applied to the pins. That's probably why it's taking so long. The parts are electrically shielded by the copper. I would think that, with the current setup, you would never strip the pins 100%. Is this true? You haven't mentioned how successful the cell is in completely stripping the parts. If they do all strip, it's probably due to the black gold connecting everything together.

The blackening of the vinyl tubing is likely due to the concentrated sulfuric and not the gold. Vinyl tubing won't stand up very long in sulfuric. It will turn black and will get hard and brittle. I think that the sulfuric removes the plasticizer from the vinyl. The same thing might eventually happen to the PVC.

I feel you would be better off with a series of lead rods, clipped together, around the entire perimeter. Current tends to travel in a straight line and to the shortest distance between anode and cathode. With one narrow cathode, you apply most of the current to the parts (and copper) closest to the lead.
 
Hmph? I was thinking the copper would help with conductivity, Now I will have to try a batch with and a similar batch without the copper. And time how long it takes for the amps to drop off. It did seem to work faster without but not as complete.

Series of lead cathodes might be a pain but one that was bent in a spiral around the inside of the cell might work.

I am sure I am not getting as much as doing one part at a time but this is a great way to do large batches. The other nice thing is you can leave it and do something else while your parts are stripping. It seems to do a very good job though.
Everything that I have run in it has yielded impressive amounts of gold. I save all the stripped material because there are sometimes spots that were not completely stripped. the trick I think is to pack it well so there are no insulated parts.

The PVC seems to hold up ok. The inserts clean up well, the black one was the one that got left in for a long time and I think it got a little cooked.
Even if I have to replace the cell after 100 batches it was cheap to build and took very little time.

I admit I am not very knowledgable about chemical reactions. I am however good at mechanical things and making something better. I used what I learned here and from Steve's videos about his gold cells to put this together. I am sure with the great minds here we can make it even better!
 
He mentions that one thing he is doing is pins.

In my many years of high volume experience with the sulfuric stripper, the best, most complete, and fastest way to use it with a large amount of small parts, is to keep the parts in motion (with the parts shifting position) and in electrical contact using a tumbler of some sort. That way, every part is equally exposed to the current. With a tumbler, your 2# of parts would be finished (completely) in, maybe, 20 minutes instead of days. Early on in the forum, this was discussed at length. When I did this professionally, I used a large ready-made plating barrel. The problem has always been to jury-rig something that is simple and cheap, that could be used on a small scale.

What if you used about an 6" - 8" length of 4"-6" PVC pipe with many holes drilled in it - small enough so that the parts don't fall out. There would be a cap on each end and some sort of clip to hold the caps on. It would have a square steel axle running through the caps and through the pipe, lengthwise, and the axle would be supported on each end, slightly above the solution - think rotisserie. The holes in the caps would be square so that the square rod would turn the pipe.

It would be loaded a little more than 1/2 full so that the parts would contact the axle. The bottom third would be in the solution (but not the axle). There would be a hand crank, on one end. You could turn it slowly every minute or so. Eventually, every part would make contact and would strip. Of course, a motorized rotisserie would be nice, and a little faster, but I don't think it would be necessary. As you ran it, the black gold would fall through the holes, into the tank. The bottom of the tumbler would be several inches above the bottom of the tank.

To supply the positive current to the axle, you could grind a short length of it round and use a spring contact against this rounded section. Also, the part of the axle that rode in the supports would be ground round.

If I were to do this, I would use a steel tank (maybe, two gallons), which would also be the cathode. There are all sorts of steel boxes in scrap yards that could be used as a tank.

This is hard to explain without drawings. It is very simple and I could make it in a day.
 
thteh said:
Which method of gold refining is safer/less hazardous and economy between cell and AR?
Click to expand...

For parts that can be run in the cell (pins, e.g.), the H2SO4 cell is far more economical. Both are potentially dangerous.
 
Thanks for the info GSP. It's better be safe than sorry. I'll leave the refining process to the experts for now. For me, they earned it.
I would not recommend anyone to refining unless they did pay attention to every detail of safety measures first and foremost. Unless you do it for a living otherwise get yourself a new hobby. Think again.
 
goldsilverpro said:
He mentions that one thing he is doing is pins.

In my many years of high volume experience with the sulfuric stripper, the best, most complete, and fastest way to use it with a large amount of small parts, is to keep the parts in motion (with the parts shifting position) and in electrical contact using a tumbler of some sort. That way, every part is equally exposed to the current. With a tumbler, your 2# of parts would be finished (completely) in, maybe, 20 minutes instead of days. Early on in the forum, this was discussed at length. When I did this professionally, I used a large ready-made plating barrel. The problem has always been to jury-rig something that is simple and cheap, that could be used on a small scale.

What if you used about an 6" - 8" length of 4"-6" PVC pipe with many holes drilled in it - small enough so that the parts don't fall out. There would be a cap on each end and some sort of clip to hold the caps on. It would have a square steel axle running through the caps and through the pipe, lengthwise, and the axle would be supported on each end, slightly above the solution - think rotisserie. The holes in the caps would be square so that the square rod would turn the pipe.

It would be loaded a little more than 1/2 full so that the parts would contact the axle. The bottom third would be in the solution (but not the axle). There would be a hand crank, on one end. You could turn it slowly every minute or so. Eventually, every part would make contact and would strip. Of course, a motorized rotisserie would be nice, and a little faster, but I don't think it would be necessary. As you ran it, the black gold would fall through the holes, into the tank. The bottom of the tumbler would be several inches above the bottom of the tank.

To supply the positive current to the axle, you could grind a short length of it round and use a spring contact against this rounded section. Also, the part of the axle that rode in the supports would be ground round.

If I were to do this, I would use a steel tank (maybe, two gallons), which would also be the cathode. There are all sorts of steel boxes in scrap yards that could be used as a tank.

This is hard to explain without drawings. It is very simple and I could make it in a day.
Click to expand...

This sounds great, I understand it well without any drawings. Will battery acid do, or does it need to be more concentrated to not eat up the base metals. Also, is glycerin needed?
 
The sulfuric must be concentrated. Battery acid will dissolve the base metals. Concentrated H2SO4 is about 96% to 98% sulfuric acid, by weight. I would use this but dilute it about 5%, by volume, with water. In other words, if you were making up 1000 ml, use 950 ml of concentrated H2SO4 + 50 ml of water. Pour the acid into the water. This slight dilution will make it strip faster.

Glycerin is not necessary.
 
Chris,

I like your Idea, I had the same concept in mind. Would you mind if I made something like this, and if it worked well, offered it to other forum members? Low cost, of course like Steve.

I believe i have access to the right parts, as far as stainless, and such. Motorized rotisserie, hmm?

Stainless basket? Stainless axle? Insulated Pb cathode around the basket.

Seems a very nice concept, any more advice or am I just gonna have to give it the old college try? LOL I like glass for small scale, and it is rather easy to clean, maybe a large casserole dish with the handles doubleing as axle houseings.

Thanks ,
Nick

P.S. I will try to start a topic to see if anyone is interested, but lacks the tools, and materials.
 
Mild steel is actually better than stainless in this solution. Stainless will be eventually attacked and will degrade.

Were it me, I would use a plastic tumbler instead of metal. I think it would be more efficient. I think the only metal drawing current should be the center contact rod and, therefore, the parts. You want the current going to the parts and not the basket. A metal basket would be easier to fabricate but I really think it would be inferior to plastic.

I also don't care much for the lead cathode you suggest. A mild steel tank would make the best cathode, in my estimation.
 
Thanks for the tips. I plan to make one. I have everything needed. I have some coarse mesh and some fine mesh plastic that's make for filltering acids.

I use the fine mesh for filtering my gold solutions. It's superfine and very tough. Pins will not get through it.

Also, have glass/plastic ball bearings for acid use.
 
How about instead of a steel tank have a plastic tank with a steel rod placed in the tank. That way the current would run from the rotating rod through the pins and into the tank mounted rod.
 
Great find Palladium, my first refinery had a professionally made barrel like that which was used for electrostripping plated wire. It was called an "oblique plating barrel" and it was about the size of a 30 gallon garbage pail and it worked like a charm. This DIY size will be great for small plated pieces, and reasonably cheap to build.
 
I think I see what you are saying GSP. I will put some more thought to it.
Mild steel really, I thought it would corrode into ferrous sulphate, extremely fast with electrolysis involved.

Thanks Again,
Nick
 
4metals,

Did your oblique bbl have holes in it (perforate type) and go into a tank full of solution or did the bbl itself contain the solution (imperforate type)?

Could you do a drawing of the setup?
 

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