Recovering Black Powder from the Cell

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Stainless doesn't last as long as copper.

Key points to keep your copper healthy:

1. Don't run your cell hot.

2. Run the highest concentration acid you can.

3. Store the mesh clean and in a sealed ziplock bag.

Steve
 
Steve
Is there a thicker copper mesh available? As much as I wait between batches, my cell can in no way keep up with my feed stock: not even if I set up two cells. I absolutely appreciate what you all have shared with me but am finding the small cell a little slow. I don't mind the work or putting in my thousand hour to learn properly. Just wondering if there is a larger rat trap

I have seen videos of higher amp deplating that is supposedly quicker but have learning curve and cost concerns.

Brooks
 
Brooks,

Larger cells will allow you to run larger batches, but strip times are relatively consistent.

Think of it like this:

It takes a well defined finite amount of electrical current to plate an atom of gold on the scrap, and it requires the same amount to remove an atom of gold in the cell. Therefore it takes the same amount of time at the same amperage to strip the gold regardless of cell size.

You can't increase the rate that the gold strips by increasing the cell size unless you also increase the current density ( and the heating) between the anode and cathode. It's very important to size all aspects of the cell accordingly: power supply, volume of electrolyte, and amperage. If you do not increase the power supply current enough to compensate for the larger cell, hence larger between anode and cathode, you will actually slow the rate of gold stripping. If you do not increase the amount of electrolyte proportional to the cell size the electrolyte will heat quickly and you'll be replacing larger parts that wear out due to corrosion.

You'll need enough cell volume and design to allow for exposure of the electrolyte to all the plated items so they all strip. otherwise you'll end up with a high percentage of stripped scrap that does not strip. This is evident in the small cell, if you have tightly packed scrap like small fully plated pins, the electrolyte does not make electrical contact with all of the pins and therefore does not strip them. These pins are in effect protected from the current of the cell. On the same track, the basket, if not properly formed around the pins will shield the pins in a 'Faraday Cage' that prevents the electrical current from passing through the pins to promote timely stripping of the scrap. The current will flow through the basket instead and decay it. This is known as the path of least resistance.

My advice is to learn the factors that affect the efficiency of your small cell, then redesign a larger one that overcomes the bottlenecks that are destroying your anode, causing heating, and slowing the overall process. Your corroding basket indicates an operational flaw to me, not a problem with the basket material.

A well balanced cell is a trade off between amperage flow, electrolyte volume, anode and cathode surface areas and configurations, scrap exposure to the electrolyte and electrical current, and proper temperature control regardless of it's size. Scale up in steps to be sure your new designs are sound in all of these aspects.

For me personally, it is better to 95% strip a 1/4 to 1/2 pound of plated scrap in small cell in a few minutes then cool the cell and reload, than to spend the effort to build a larger cell that takes days to 95% strip a few pounds of plated scrap. Keep in mind the larger cell means larger volumes of sulfuric acid to filter, transport, and recycle. Again the larger cell takes the same amount of time to strip the same scrap at a given current density (amps per square inch) regardless of the size of the cell.

The larger cells offer advantages in the time required to monitor the cell operation. They can be loaded, set to run, and left on a timer to complete after a trial run to determine the safety of the set up. You will still have some percentage of the scrap that remains partially or fully plated. Scaling up is perfectly feasible, but not as simple as you may imagine.

One last thing to think about is the time between clean out the cell and batch processing. Large cells do not lend themselves well to determining actual yields for a particular type of scrap. The small cells are well suited to this since they are easily cleaned out. A large cell takes longer to become saturated with gold, so your values will be tied up in the batch.

All in all it's a trade off between your goals and the proper size of the cell you design.

I hope this helps. I'm hoping others with cell experience will post their suggestions also as this is only my take and guys like GSP and Oz will surely provide some different angles on the benefits and problems than I do.

Steve
 
Steve

It helps a lot. Thank you.

It makes sence to perfect what I am using now to better future aspirations.
I have had some issues that perhaps you could educate me on. First off, I use the same equipment as in your videos (the only difference is that I am using a very old 6amp battery charger with a reducer switch to 3 amps.) I have completed 5 batches to date with about an ounce recovered, on the average: per batch. My feed stock is mostly mil spec. connectors. However, I have been experimenting with everything gold plated.

My questions are:

My charger typically starts kicking off and on when I am on my third copper mesh batch. It runs smoothly for the first two, each and every time. Never kicks off when not using mesh. Why is this happening? The way I have been compensating for it, is to reduce charger to 3amps (when it kicks back on and then towards end of batch, I turn it back to 6amps and typically stays on.

When rinsing copper mesh of black powder from last batch, how dry should the mesh be (from water) before proceeding with next batch?

I have been washing cell mud with HCL multiple times before AR and still getting dirty gold. Should I be boiling the mud during HCL wash?

Thanks again for the info.

Brooks
 
I would probably leach the filtered, rinsed (I would use distilled water for the final rinse or two) mud in nitric first, to remove any base metals, and then, after filtering, I would dissolve it in aqua regia and go from there. As an alternative, you could probably use HCl/H2O2 to remove base metals and then dissolve the gold in HCl/bleach. I doubt if you'll ever get clean gold without doing one of these. Although some have tried, no one else, that I know of, has gotten pure (999.5 or better) gold by just melting the residue directly (no matter what it had been leached with). I think you'll have to refine it first.

When I did this on a large scale, I just dissolved the mud directly in aqua regia. However, I had a 50 gallon tank and a $1500-$2000 plastic barrel plater that I tumbled the parts in. Since the solution temperature rarely exceed 100F and since I had a big plating rectifier, with tight controls over the amperage, I had little or no base metals in the mud. For some parts, such as old side-braze CPUs, I mounted each part separately on a plating rack, using spring contacts made from piano wire. Depending on the size of the parts, a 2-sided rack would hold up to 700 CPUs. The rack, itself, was made of exposed 1/4" square brass stock. After 2 years of daily usage, the brass wasn't noticeably attacked. On the racks, the gold brazes were stripped in 15-20 minutes. We had about 10 racks (along with a couple of girls to load them) and we stripped parts all day. In the barrel, pins stripped 100% in about 5-10 minutes, if I remember right. I would guess that we ran 10-20 pounds of pins at a time, maybe more.
 
GSP

I am sorry that I did not make myself clear enough. I have already dropped gold from solution. That gold color is dirty. I intend to refine again so I have not melted anything.

I was trying to find out the best cleaning method for removing base metals from cell mud before I dissolve with HCL/ Clorox. Of all the drops I have done, the cell gold is the dirtiest. I washed it multiple times in water till there was no color and twice, for days at a time, in HCL prior to HCL/Clorox.

Thanks, Brooks
 
bklopsy said:
GSP

I am sorry that I did not make myself clear enough. I have already dropped gold from solution. That gold color is dirty. I intend to refine again so I have not melted anything.

I was trying to find out the best cleaning method for removing base metals from cell mud before I dissolve with HCL/ Clorox. Of all the drops I have done, the cell gold is the dirtiest. I washed it multiple times in water till there was no color and twice, for days at a time, in HCL prior to HCL/Clorox.

Thanks, Brooks

Do you have the chemicals to do a hot 50/50 nitric leach on the mud from the cell and then use aqua regia? I assume you do, since you mentioned using AR in one of your posts. I would think that nitric would be much more effective in removing base metals than HCl would.

Also, are you following sound methods for the AR? Is the solution crystal clear before you drop the gold? Did you add a little sulfuric to the AR to drop any lead (especially if you are using lead anywhere in the system or have solder present on the parts)? Was all the silver removed? When you drop the gold from AR, does the powder look slightly gray? That could be Pt, although I don't know where it would come from.
 
GSP
I knew someone would catch that. I said AR in that post in hast: I actually disolved with HCL/Clorox. However, to answer your question, I do have 500ml of 70% enviromental grade nitric. I was saving it for dequarting some karat jewelry I have----AND------it was not easy to get or cheap. I did think of doing it with the nitric but thought that would be costly. That nitric cost me $100

The solution did turn crystal clear for about two seconds---then to a pail/faint blue before over taken by brown color. I did not add sulfuric to solution because my thought process was that it was in sulfuric when deplating. I guess I'm about to learn something.

I definately have lots of silver sediment from all batches I have saved them into a seperate container for later refining. After dissolving and settling, I have siphoned all solutions

Thanks, Brooks
 
bklopsy said:
GSP
I knew someone would catch that. I said AR in that post in hast: I actually disolved with HCL/Clorox. However, to answer your question, I do have 500ml of 70% enviromental grade nitric. I was saving it for dequarting some karat jewelry I have----AND------it was not easy to get or cheap. I did think of doing it with the nitric but thought that would be costly. That nitric cost me $100
Thanks, Brooks

Man, $800/gallon nitric is a bit pricey. That's 50 times more than what I just paid. I'm sure you realize that the much cheaper tech grade works equally well for our purposes. Where are you located?
 
GSP

I am located in Connecticut. The problem I found is that no one is willing to sell to an individual or send nitric to a residence. The liability is a huge issue for most company's. They want your Fed Tax number and they will only send to a business. If you have a good source, I'm all ears. Well, eyes in this case. Even the tech grades I have found are expensive.

Thanks, Brooks
 
Someone in Conn. or, thereabouts, please help this guy find some cheaper nitric.

I think someone on the forum recently posted that he bought 5 bottles of nitric and paid $65 total shipping. I don't remember the size of the bottles or the price.
 
That sure would help. I'd dissolve all my base metals out that way.

I just read a post that mentioned BC Scientific. I looked at site and pricing is better that what I've been paying. Can someone please advise me which nitric to get for tech grade is not mentioned.

Thanks, Brooks
 
I bought six 2.5 L bottles from BC. They only had ACS grade, but it was still the cheapest I found with shipping and all.

I paid $315 or so to my door.

Steve
 
Steve

Thank you very much. I placed order with you for addition node and mesh so I can start running two cells. Did you read my post about my battery charger that keeps kicking off and on?

Thanks, Brooks
 
Brooks,
Is your battery charger an automatic or manual charger?
If its automatic that is probably the problem. I had the same
thing with a charger that was supposed to be manual/automatic,
but didn't seem to work any different on manual, so I assume it
was broken.Now I have a manual charger that works fine.

Jim
 
Jimdoc

I honestly do not know the difference. I have a single switch that allows me to choose between a fast (6amp) charge or a slow (3amp.) charge: thats it. However, on another note, I had problems being able to use the first two chargers that I have owned for years. They simply would not work with the cell.

My neighbor had an old one that he gave me and it worked from the first batch on---except of course for this little inconvenience that I have learn to deal with. The charger I am using is from the seventies and the two I own are about 10 - 15 years old.

What is the difference between an automatic and manual charger

Brooks
 
Brooks,
I forget who it was, but someone on the forum hooked a battery up to the charger and it worked,maybe you can try that.That would keep the charger working and stop it from kicking off.Then you would know to lookout for a manual charger.

Jim
 
Here is a link to the posting;

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=7266&p=66352&hilit=battery+charger#p66352
 

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