Electrochemistry modified reverse electroplate theory

[resident_genius]

i was toying with the idea of using an electric current to dissolve the copper on my gold filled items, or to help strip the gold electro-chemically and put it onto the cathode.

utilizing basic cell theory from lasersteve and a muriatic acid/peroxide mixture (2:1) electrolyte, i was thinking of making my gold filled items the anode and using electric current, strip the gold from the anode and deposit it onto the cathode. is this possible/feasible? or, if my understanding of hcl and electroplating is off, would the acid attack the copper instead and drop it to the bottom of the cell?

i could use a sulphuric/glycerin electrolyte and strip them that way, but i liked the way that the muriatic attacks copper and not gold.

any thoughts, opinions, ideas on the subject?

i just ordered in my sodium nitrate, so i could try a small batch of my gold filled items with some poor mans AR and then precip the gold.

 

[goldenchild]

HCL and peroxide will dissolve everything. Sounds like you are trying to create something that works like cyanide. I don't think your theory will work.

 

[goldsilverpro]

Concerning electrolytic systems. Dilute sulfuric (10-15%) will attack copper but not gold. Muriatic will attack both. Concentrated sulfuric (you don't need glycerin) will only attack gold. I once came up with an electrolytic cyanide system that stripped only the gold. That's about it.

For the dilute sulfuric, the problem is plating out the copper as a sound cathode deposit. If the copper is alloyed (it usually is) with such things as zinc, this is difficult if not impossible.

 

[Lino1406]

Why don't you put it all in persulphate + H2SO4
solution (+ H2O2 also can help)

 

[goldenchild]

resident_genius,

Is there any particular reason you want to get the copper out as a metal? Nitric acid does exactly what you want this cell to achieve. Attacks the copper leaving the gold intact. Then you could easily precipitate the copper. As GSP has conveyed, unless you're starting out with high purity copper, the cell won't work well anyway.

 

[Harold_V]

As GSP has conveyed, unless you're starting out with high purity copper, the cell won't work well anyway.

It is my opinion that he, like many of us, will learn that lesson only by trying, and failing to accomplish the mission. Some folks, at the outset, don't learn by the mistakes of others.

Harold

 

[Oneal58]

Hi Everyone, is it best to try and reverse electroplate the gold filled items I have or just melt the watch cases and make some shot and then drop a small test batch into Aqua Regia just to see is it worth the effort and expense in acids. I don't understand how Gold Filled items which are (mostly antique) are put together yet. Are they plated or have some amount of gold thoroughout. Is there enough gold in them to go this route or would it be a waste of good Aqua Regia and time. Isn't the gold filled returns going to have tin, copper, zinc, solder, lead, Ect:. in it also? To get good quality return shouldn't I melt everything and then start fresh with AQ and go through all the steps of recovery or is there a simpler route? I see a lot of the watches have gold filled and some have gold filled plated. Or is there any difference, at all, only the words used? Woud you use a difference porcedure on each for best results? Thanks for your time, Oneal58

 

[nickvc]

Gold filled or rolled gold as it's called here in the UK is exactly what it says. The original billet of metal is fused with a sheet of gold top and bottom and then rolled to the correct thickness and width before the items are stamped and assembled. The actual amount of gold stamped on the item would have been correct at the start but with processing,polishing and wear it never is what it says by the time we get our hands on it. You can also get gold on silver but it's rarer and the same applies to this it's rolled and stamped,wires are usually seamless filled tube that is drawn to size before been formed.

 

[Harold_V]

Hi Everyone, is it best to try and reverse electroplate the gold filled items I have

Not a good idea. The nature of stripping cells is such that they are very effective on pure gold, but not so good on alloyed gold, which is what you have with gold filled items.

or just melt the watch cases and make some shot and then drop a small test batch into Aqua Regia just to see is it worth the effort and expense in acids.

Also not a good idea. Have you read Hoke?

If not, why not?

I don't understand how Gold Filled items which are (mostly antique) are put together yet.

Read Nick's post. He covered it very well, in just a few words.

Is there enough gold in them to go this route or would it be a waste of good Aqua Regia and time.

If you used that approach, yeah, it's a waste of time. You clearly don't understand how such material should be processed. If you were to approach the project from that perspective, there'd be no end to the problems you'd encounter, all of which can be easily avoided.

Isn't the gold filled returns going to have tin, copper, zinc, solder, lead, Ect:. in it also?

Bingo! So then, if you understand that, why would you want to dissolve all of them along with the gold? See where I'm headed with this?
(By the way---and please take this in the spirit it's offered----ect is NOT a word. If you're looking for the contraction of the two words et cetera, it's spelled etc)

To get good quality return shouldn't I melt everything and then start fresh with AQ and go through all the steps of recovery or is there a simpler route?

For starters, I'm not sure what you mean by AQ, although I expect you meant to type AR. Lets go with that thought.

One does NOT dissolve everything along with the values when there are options. Gold filled is certainly top of the heap where this matter is concerned. Gold filled is generally 95% base metal, all of which is troublesome. Have you given any thought to NOT melting? Think a moment about this idea. First, remove any parts that are magnetic. Avoid including steel in your refining circuit. Also, remove any aluminum should there be any present. The pieces are then heated to dull redness (but NOT melted). That burns off any oils and other substances that can be problematic. You then go after the base metals with dilute nitric acid. The resulting solution will contains traces of silver, along with several other base metals, and will yield thin sheets of the alloyed gold, along with miniscule particles. The material should be subjected to nitric until all base metals have been dissolved. The remaining solids, including the fine sludge that is sure to be a part of the solids, is then gathered in a filter. When dry, it should be incinerated to redness, but, again, do NOT melt. After incineration, screen and go through the material with a magnet. The material should then be given a wash in hot HCl, then rinsed until the rinse water is clear of color. Only then should you dissolve the gold.

It's all in Hoke (except for the HCl wash after incineration, which is one I developed to aid filtration for such material).

You can run gold plated items the same way, although, with the cost of nitric acid, you're better served to strip such items with a sulfuric stripping cell, or to use the AP process that is well discussed on this forum.

Read Hoke! Then read it again. Read until the things I've talked about here make sense to you.

Harold

 

[Oneal58]

Hi Harold,
Thank you for your help. I honestly have read Hoke's Book, many chapters such as 5 and 6 many times. I am not making excuses here but I am not as sharp as I used to be before my heart attacks. I know I miss a lot when I read or (type ) material anymore but that isn't going to discourage me any. Or keep me from doing something I have wanted to try all my life. I just have the time now to give it a try now . But, thank you. I have already printed your directions out and have them in my hand. If I have to work through your instructions a sentence at a time I will get my satisfaction, get that itch scratched. But I understand what you have said, and will follow your directions to the Tee. Wait a minute, is that the same thing as Ect? But thank you in advance for any advice you could throw my way now, in the near future, or Etc;. :lol: No, really, thanks Harold. I will let you know how I do.
Oneal

 

[Harold_V]

Oneal,
One of the real tragedies of my position is I'm unable to know of the other guy's hardships and handicaps. It helps tremendously to hear about your health issues and to know you're trying. We get so many here that have an entitlement attitude and are bordering on being unwilling to help themselves in any way. I see, clearly, that is not the case with you.

I'm not the sharpest knife in the drawer, not having a formal education, but this I guarantee you. If you follow my advice, in particular, studying Hoke's book until it does make sense, you should find yourself in a position to deal with pretty much anything you're likely to encounter. I say this because that's exactly how it worked for me. I took no chemical classes in school, yet learned to refine to the point of doing so commercially for about 20 years. I retired as a refiner, selling the humble business I founded. If I can do it, you can do it. You can also count on me for guidance if you feel the need, although in many cases there are others with much better knowledge and experience on the forum. I'm good at working in the trenches, so to speak, considering I learned everything the hard way.

Thanks for sharing your story with us. I think we all have a much better understanding of your position now.

Do try the method I proposed. It eliminates a lot of problems. Here's one of them that is vexing. Some gold filled material is assembled by soft soldering. In any event, in spite of how it may be assembled, if you melt the gold filled items before processing, the gold is so finely divided that it manifests itself as nothing but fine black particles, bordering on being colloidal. That makes them very difficult to deal with. By not melting, you can fully eliminate the base metals, leaving behind a thin layer (along with some fine particles) of gold alloy, which has also been leached of much of its alloying material due to the relative thinness of the gold filled layer. When you separate the resulting solution from the remaining solids, virtually all of the troublesome materials are eliminated. Those that remain are altered by incineration, then the HCl wash I mentioned eliminates a great deal of them, so the end result is a relatively clean gold material that will now filter without issues.

You'll come to understand what I'm talking about when you run the first batch. Run the material by heating the dilute nitric, and run it until there is no further action. You should notice a general pink to purple color of the resulting solids, a sign of the presence of finely divided gold and tin. The process I speak of will eliminate the loss of any values, assuming you follow the instructions as they've been presented.

Thanks for your understanding. I didn't like making mention of your spelling of etc., but it's a pet peeve of mine. Drives me crazy!

Best,

Harold