Silver Cell?

Thanks, Chris.

Recovering the silver on copper won't work?

Harold

You still have to dilute it first to cement it. With cementation, you'll end up with a mix of silver sulfate and silver metal. Cementation with strong sulfuric won't work because copper is only slightly soluble in strong sulfuric. In order for silver to cement, copper has to dissolve but, the strong sulfuric won't allow it to dissolve.

Strong sulfuric and weak sulfuric are like 2 totally different acids. Once above about 85%, sulfuric starts doing some unique things.

I knew the son of a guy that died from cyanide inhalation or ingestion. He was dissolving the silver solder that held the carbide tips on scrap coal mining bits. He was running several drum quantities and working inside with no fume control.

A few rules for cyanide are: Don't get it in your mouth. Don't mix it with acids, even something as weak as coffee. Don't work in a confined area. Don't smoke or drink around it. Don't work over hot cyanide - your skin will break out with "cyanide itch". Wear gloves and a face shield. Get an excellent fume hood

Your friend didn't know or obey the rules. You must obey the rules with cyanide.

Hmmm. As I recall, the patent calls for a sulfuric with a specific gravity of 1.65, and is suited to removal of silver. I have no clue of the specific gravity of highly concentrated sulfuric, although I know it's considerably heavier than water. Perhaps it is 1.65. Dunno.

The process of precipitation on lesser metals is an electrolytic reaction and doesn't really rely on dissolution so much as it does an ion exchange, at least as I understand the process. If there is an exchange, copper will go into solution as the silver is precipitated, creating the illusion of being dissolved. I think someone should give the process a go and see what happens. It could be done on a small scale with little invested. If copper works for recovery, it would be a piece of cake----and residual copper, exchanged by the silver that was in solution, could be recovered from the sulfuric electrolytically as virtually pure copper. The acid could be endlessly recycled, or so it seems.

This is one of the things I'd have enjoyed working with before I closed the doors on my refinery.

I understand your comments about the differences in dilute as opposed to concentrated sulfuric acid. It's a strange critter!

Harold

I think 96% sulfuric has a SG of 1.84. I just reread the patent and it doesn't mention how to get the gold or silver out of the solution.

How can the copper give the illusion of being dissolved? It is or it isn't. The copper can't be obtained electrolytically unless it's dissolved. There is no difference in "going into solution" and "dissolving"? It's 2 ways of saying the same thing.

Thanks. I was thinking that the s.g. of concentrated sulfuric was higher than 1.65, but wasn't sure. That's considerably higher than the recommended concentration, and would likely work as I suggested. You're already dealing with a fair amount of water. That also explains why the patent suggested that there might be a loss of physical size when stripping ferrous objects. With highly concentrated sulfuric, that would likely not be the case.

Precipitation of gold isn't an issue. As the dissolved gold migrates away from the proximity of the anode, it self precipitates. That may not be true with silver, which is known to dissolve in sulfuric without the aid of applied electricity. The question of recovery is the real stumbling block, for it damned well will strip in the typical sulfuric cell.

About dissolution; You're right-----it's either being dissolved, or it isn't. That's true regardless of the approach, be it strictly by acid, or with the aid of electricity. Being an ex-plater, you understand that in ways that others might not, myself included. Electroless nickel works by electricity, but it does not require that electricity be provided-----it creates its own ion exchange to support the deposition. I'm of the opinion that recovering silver from a sulfuric solution with copper will do likewise.

Each of us knows that copper is not soluble in sulfuric, nor is gold, yet it dissolves when electricity is applied (the ion exchange I spoke of). That's the basis of a copper cell. And so it is with precipitating one element with another. While it isn't truly dissolving in the sense of going directly in to solution, it still goes in to solution via the exchange of ions, it's a matter of having the ion created by an outside source. Bottom line is that it's not necessary for sulfuric to be able to dissolve copper in order for copper to precipitate silver than it is for sulfuric to be able to dissolve gold, or copper, for cells of that nature to function. Both of us agree that a sulfuric cell works----and this is nothing more than the same thing in reverse, sans the added electricity. I'm of the opinion it will work-----and I think one of these guys that feel recovering silver is a worthwhile objective should give it a go. I may be wrong, but nothing I'm reading thus far indicates I am.

As an after-thought, one might be pleasantly surprised to find the silver self precipitates when the concentration is high enough. The solution will support only a given amount, then it has no options. As I said, this is one of the things I wish I'd have explored before closing the doors on my refinery.

Harold

goldsilverpro

Before I joined the forum I learned mostly from trial and error!

I tried straight hcl (31% from home depot) on 4lbs of low grade pins from mother boards etc. in a bucket. When it quit working aggressively I presumed I had removed most of the lead etc. that the hcl would remove. It reduced the bulk considerably but left about 3 cups of whitish powder on top of my mostly divided gold.

At that point I switched to dilute sulphuric (about an ounce of sulphuric or even less per 2 cups of water) to remove the remaining tin. But action was slow so I put it in a pyrex pan on hotplate with heat at a very slow boil which made the dilute sulphuric hold a considerable amount of tin etc. After siphoning hot dilute sulphuric with tin I would pour in a 5 gallon bucket. When cool the tin drops out almost completely thus I can reuse the dilute sulphuric over and over while collecting my tin etc. at the same time.

Adding sulphuric to sediment while hot was dangerous. I fill the still hot pyrex pan with tap water which cools the pan and sediment slightly. Adding while slightly cooler around 1/2 ounce sulphuric acid slowly with very little spattering but it does gurgle some. I let this sit and heat for around 1/2 hr till milky white with dissolved tin etc. then repeat again over and over.

When the contents of my bucket are cool with the tin almost completely settled I siphon into a second bucket without sediment and reuse this dilute sulphuric solution over and over in pyrex pan.

This method seems a little faster than hcl/peroxide for removoving tin etc. but requires more attention.

This method would be more effective in crockpot because of larger size. Do you think hot dilute sulphuric in crockpot would present same danger of attacking glaze and possibly cracking ceramic etc. ? Would this work on silver plate even if slow?

Thank You for your patience with a new guy!

Wayne

I'm really liking this closed loop dilute sulphuric technique for silver recovery because I'm not generating a large liquid waste stream. Although I'm leaving a finite amount amount of silver etc. in solution at all times, its not lost but will have to be dealt with at some point. Adding additional sulphuric equal to approximately amount of work done is no problem. Might be better to go by ph level?

Just recovering so far will have to clean up sediment at some point and try karo and lye. May wait until I have around a pound or so to fool with.

Have read that reduction to metal is also possible in kiln at way below melting point of silver with little smoke etc. Might try in propane forge!Has anyone done this?

Not sure of cost of materials etc to recover yet or what percentage of sediment is actually silver etc.

Thanks

Wayne

GSP,

On the subject of dropping silver from silver sulfate: Have you tried powdered/granular zinc metal. If so what was the outcome? If not, what do you think of this as a possible percipitant for the dissolved silver in the cell?

I'm not really into silver recovery so this is merely a passing thought.


Steve

The first picture is cell with all water & one cup roto. Worked fast with crockpot on low temp. setting. But kept having to reset battery charger due to resistance of tap water I guess.

The second picture is crockpot cell with liquid fire two bottles (64 ounces)
with one cup water. It stripped silver plating off as fast as I could put it in cell. Couldn't count to ten fast before it was through. Crockpot was on low low heat setting. Using 10amp ,12volt charger on manual setting.

Full strength liquid fire as from bottle was slow; diluting a little makes much faster.

Ceramic hasn't stripped or broken yet.

Third picture is stripped candle holder parts after stripped.

Full credit to Goldsilverpro & Lazersteve as I working off their knowledge and ideas with slight modifications. Goldsilverpro, I very sorry I disregarded your safety info. and did this anyway. I hope you won't hold this against me as I truly respect your opinion! We currently sell more silver than anything as heavy gold pieces just aren't moving. So this silver is pretty compelling.

Wayne

Nice work!

I'm curious. What happens to the silver in solution when you leave a piece of the stripped copper alloy behind? (Simply submerged in solution, not connected to anything). Do you see signs of cementing of silver? If you can pull the silver from solution with copper, you'd be well ahead of the game. The silver could be washed, melted and cast into anodes, ready to be parted. I'm still struggling with the idea that it should work. GSP advises that it won't, but I have that little nagging doubt.

Harold

This thread has been confusing from day one.

To prove this, one way or another, I would suggest taking a pure silver bullion coin and dissolving a good portion of it in the sulfuric stripper. Weigh it accurately before and after and record the weights. When finished, try to reclaim all the silver from the sulfuric using copper cementation. Compare the recovery weight against what has been dissolved.

BTW, I do really hope I am proven wrong on the cementation. If would be nice to have a simple way to work silver plate.

Harold

I'll be glad to try and take a picture of the results.

I like the dilute sulphuric cell the best as it automatically dumps quite a bit of material upon cooling. Holding more upon heating again repeating over and over. I'm only using 10amp charger, 20amps or more should run 64 ounce water, one cup sulphuric cell just fine. GSP is absolutely right about hot concentrated sulphuric it's rude and dangerous. I'm not completely sure a thin wall tupperware container would hold up if entire contents of crockpot spilled at once!

With the dilute or concentrated sulphuric cell using copper cathode a lot of mostly silver is built up in blackish sludge form on cathode front and back not really adhered, just wipe off into cell with plastic spoon or you can just remove cathode and wipe build up in container to collect. Just as in gold plate cell once sulpruric is saturated it drops as blackish fluffy precipitate very similar in appearance to sediment in gold cell. Just let settle then siphon or pour off sediment to collect or dilute and filter then precipitate etc.

The copper alloy base material is affected very little in this process. In crockpot size cell I'll have to use a larger power supply to try basket method to deplate more material at one time. With just one small piece at a time in concentrated sulphuric using hemastats to hold as in picture is all my charger will handle. I should try Steve's cell for this with same power supply to note difference in current requirements for deplating silver and gold plate by roughly equal weights. Should be fairly equal.

Like GSP said the cell in Steve's video should work great with a slight dilution of acid with very little water as per GSP's instruction earlier in this thread. I don't believe the glycerin would hurt anything. Dilute or concentrated, hot or cool silverplate is easy to deplate. I think economics of small return was the reason it wasn't done more years ago and now. The process is almost identical in action as when deplating goldplate.

Most of my scrappable silverplate is in storage in country down three miles of very poor dirt road, and we've had historic amounts of rain lately. Might be another week before I can get to it. Stiil much better than
being stuck there wishing I was in town. I'm really having a lot of fun with this!

Thanks for all your help on forum!

Wayne

goldsilverpro said:

BTW, I do really hope I am proven wrong on the cementation. If would be nice to have a simple way to work silver plate.

Click to expand...

Judging by the copper cathode Wayne has been using, it appears you are dead right about silver not precipitating on copper from a sulfuric solution. All I can say is "Rats".

I don't mind being wrong, but it really sucks that it's not a viable solution. Sure is a nice feature when working with silver nitrate!

He has also explained to my satisfaction that the silver behaves much like gold, and self precipitates from a stripping cell, although a small amount remains in solution. I don't see that as a problem, especially if the solution is recycled as you've suggested in previous posts.

Good call, Chris!

Harold

austexjwlry said:

I'll be glad to try and take a picture of the results.

Click to expand...

I'm following you quite well, but it might be interesting for the readers to see what you've done, and how you've done it. Posting a pic is likely a good idea.

I like the dilute sulphuric cell the best as it automatically dumps quite a bit of material upon cooling. Holding more upon heating again repeating over and over. I'm only using 10amp charger, 20amps or more should run 64 ounce water, one cup sulphuric cell just fine.

With the dilute or concentrated sulphuric cell using copper cathode a lot of mostly silver is built up in blackish sludge form on cathode front and back not really adhered, just wipe off into cell with plastic spoon or you can just remove cathode and wipe build up in container to collect. Just as in gold plate cell once sulpruric is saturated it drops as blackish fluffy precipitate very similar in appearance to sediment in gold cell. Just let settle then siphon or pour off sediment to collect or dilute and filter then precipitate etc.

Click to expand...

You might consider a water cooled cell. I'm of the opinion, based on your comments, that the silver is precipitating via electronic deposition, although not an adhering film, so the process is likely open ended, as long as you can keep the temperature under control. I'm pretty sure you don't have to allow the silver to precipitate to proceed. Has that been your experience?

Your one statement leaves me with a question. The one about filtering and precipitating, etc.. I would think that the slimes you recover are in need of nothing more than a rinsing in water, then melting and casting as an anode for parting. They should be of high quality silver, although not pure, assuming you're not mixing precious metals. Have I missed something?

The copper alloy base material is affected very little in this process. In crockpot size cell I'll have to use a larger power supply to try basket method to deplate more material at one time.

Click to expand...

That's in keeping with the patent of the process. It's supposed to strip without affecting the base metals. One thing that is interesting is the wide range of specific gravity of your solution. The patent calls for a given concentration. Looks like it's not nearly as important as portrayed.

The cell I witnessed was water cooled and used a copper basket. You're on the right track-----but you're going to have to do something about the heat generated, otherwise the cell won't be able to run very long.

I think economics of small return was the reason it wasn't done more years ago and now. The process is almost identical in action as when deplating goldplate.

Click to expand...

A steady supply is likely more of an issue than anything. It's been known right along how silver can be stripped, but the relatively low value is quickly eaten up by wages, and would likely be the same in today's market. Still, for a guy that enjoys the work, and has a good supply of plated items, the silver can be profit, while the stripped base metals can recover the investment cost. I think you're on to something, but it would be difficult to do for a living.

Most of my scrappable silverplate is in storage in country down three miles of very poor dirt road, and we've had historic amounts of rain lately. Might be another week before I can get to it. Stiil much better than
being stuck there wishing I was in town.

Click to expand...

We've heard several reports on the weather in your area. Hope you're doing OK---so many are not so fortunate.

Harold

Harold said:

Your one statement leaves me with a question. The one about filtering and precipitating, etc.. I would think that the slimes you recover are in need of nothing more than a rinsing in water, then melting and casting as an anode for parting. They should be of high quality silver, although not pure, assuming you're not mixing precious metals. Have I missed something?

Click to expand...

I'm not 100% sure what he's seeing is elemental silver. From his description of how it drops when the solution is cooled, it appears to be a compound of silver (Silver Sulfate, Ag2SO4). If this is the case he has another purification step before the melting begins.

I asked GSP a specific question earlier in this topic and his answer seems to support my belief that Wayne is dealing with Silver Sulfate.

Here's the link to my question :

Silver from Silver Sulfate

and:

GSP's Reply

The silver cell mystery deepens....

Steve

Here's my general understanding of what is happening. This is what's in my memory bank. I can't find any sources to back me up, in several of my statements.

Silver sulfate, the compound produced when silver is dissolved in sulfuric, is very soluble in concentrated sulfuric acid. I don't remember how soluble, but I seem to recall at least 50 to 100 ozs per gallon. Big numbers. As the H2SO4 concentration decreases, the silver sulfate solubility decreases until, at zero H2SO4 (100% water), the solubility is only 5.7 grams per liter (.69 tr oz per gallon).

Copper sulfate is just the opposite. It is very soluble in weak sulfuric but nearly insoluble in strong sulfuric. I also seem to remember that, the small amount of copper that dissolves in strong sulfuric forms as cuprous sulfate, which is a gray powder, when out of solution.

These solubility numbers can also be called saturation numbers. When a solution is saturated with a certain chemical, no more of that chemical can be dissolved.

I read those comments previously, but I failed to grasp the significance. I now realize that I was missing the fact that silver sulfate is soluble in water, unlike silver chloride. It can be compared with silver nitrate in that sense, and I was overlooking that concept. As I mull this over in my head, things are making more sense----a learning curve that I avoided when I refined------a lack of need, really. I was totally comfortable with working with nitric and silver and had no unanswered questions. This is a whole new world for me.

Does silver sulfate reduce to elemental silver by furnace in the same manner silver chloride does? If so, one would than choose to melt with soda ash, and disregard my comments to melt using only borax. You're in a compromising position of encouraging the reduction of unwanted oxides of base metals as one of the costs of recovering the silver sulfide.

The comment of precipitation now makes sense---

Thanks to all for helping me understand the process better.

Harold

Noxx said:

Mixing conc. Nitric and Sulfuric is also dangerous because if you drop or soak accidentally some cotton in it, you just made a very powerful, shock and friction sensitive explosive ! :shock:

Click to expand...

This is called guncotton or smokeless gun powder. That is why people must also know that mixing Nitric and Sulfuric acids along with Glycerin as used in the electrolytic cell will create Nitroglycerin which is the UNSTABLE form of Dynamite!

Kory,

A member had previously discussed this same topic here:

Nitroglycerin in the cell

Steve