Hello! I prepared 16 liters of aqua regia and dissolved a lot of gold-plated parts in it. My question is, do I want to cement it with copper and does copper also cement silver? I want to use copper because here in Hungary the ingredients are expensive, for example: 1 kg of urea is $20.75. Would you write about this process? Thanks!
Does copper only knock out gold or does it also knock out silver?
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How did you prepare the AR?
What did you dissolve?
Copper will cement out everything below it in the electrochemical table.
Which means Gold, Silver, PGMs and Mercury.
Just check the electrochemical table.
for example: transistor, I put the gold-plated pins from the connectors, a whole connector that I couldn't take apart, and other things, it was quite mixed, there was a lot of things in it. I made the royal water in a ratio of one to three. Thank you for your answer!
DO NOT premix your AR, add HCl to barely cover the things you want to dissolve, then add Nitric by the "drop" little by little until it is dissolved.
AR dissolves very little Silver, was there anything left, after the AR stopped reacting?
Edit to add:
Silver will be left as a metal with a crust on it.
Have you done a Stannous test on it?
We really don't like dissolving batches of everything, it makes it almost impossible to help and solve issues.
Search the forum for Stannous test.
How can you know what to do if you don't know what you have in solution?
You definitely don't have much Silver, if there was it would be left on the bottom.
Testing is simple, take a ml or so and add a few grains of Salt, if it creates a white fluffy precipitate it has Silver in it.
But there shold not be, since there is HCl in the AR.
How can you know what to do if you don't know what you have in solution?
You definitely don't have much Silver, if there was it would be left on the bottom.
Testing is simple, take a ml or so and add a few grains of Salt, if it creates a white fluffy precipitate it has Silver in it.
But there shold not be, since there is HCl in the AR.
Sorry, I'm talking about two separate things. I cemented one of my solutions with copper, I got quite a lot of brown powder (I'm drying it now), I think there is iron hydroxide on top, but then according to them there is also silver in it. I put powdered integrated circuits in my other solution and I want to cement this solution with copper, but silver is not needed. This is also 16 liters.
That do not matter, Silver will not dissolve in AR (a minute amount can to some degree)
And there will not be any Iron dropping from cementing with Copper.
No Hydroxides will form in AR unless you start neutralizing it.
You will need to stop this experiment now, you obviously do not have the knowledge to do this hobby safely.
Set everything aside and start studying.
First read the book from C.M. Hoke. there is a link in Frugalrefiners posts.
Then start searching the forum.
someone is talking about iron hydroxide here, there was just such an oily film on top of my royal jelly and it was the same color.https://goldrefiningforum-com.translate.goog/threads/copper-cementation-process-and-results.29779/?_x_tr_sl=auto&_x_tr_tl=hu&_x_tr_hl=hu
That is in Hungarian, so I can't comment it.
But never the less, Hydroxides form when the pH allows it and the conditions are right.
It will as far as I know not form in AR, is that what you mean with Royal Jelly???
Please use proper terms for chemical compounds.
My advise still stands. put your solutions aside in good containers and start studying.
Search especially dealing with waste.
I wanted to neutralize the nitric acid with sodium carbonate, but it didn't work out, so I cemented it with copper, and I think that's why there was iron hydroxide on top. What do you think? Why does silver not dissolve in AR?
You should start studying now mate.
Silver forms Silver Chloride in when in contact with any Chloride.
It can not be dissolved in any acid and when the layer get thick enough the Nitric can’t get through.
We never neutralize our acids.
If we use too much Nitric we may destroy it with Sulfamic acid.
In some cases we raise the pH to perform some actions that need a specific pH to be effective.
Thats it.
Start studying now so you don’t hurt yourself or others around you.
Edit spelling.
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I totally agree. You know even less then I did when I started. Please take his advice and rest everything about this subject.
Copper will cement anything more noble - gold, silver, PGMs, mercury etc... Putting the copper into the PM loaded AR will cause all precious metals to drop on it. After the nitric acid will deplete from the solution of course.
It is very advantageous to also know the theory behind. Because if you encounter any problems along the way, you will be more able to solve them by yourself.
And I does not believe kilo of urea cost 20 USD in Hungary. Fertilizer grade could be purchased for few euros for 5kg bag in gardening stores. By the way, don´t use urea. Use sulfamic acid instead. Or if you cannot source any sulfamic, stick with copper precipitation.
Learn how to do things how they should be done. There are hardly any shortcuts in this business. And also, never pre-mix AR. Dose nitric acid incrementaly. You save precious nitric by doing so, and also it is much easier to process afterwards regarding excess nitric removal using sulfamic. Adding bases does nothing to the nitric or nitric residues.
It is very advantageous to also know the theory behind. Because if you encounter any problems along the way, you will be more able to solve them by yourself.
And I does not believe kilo of urea cost 20 USD in Hungary. Fertilizer grade could be purchased for few euros for 5kg bag in gardening stores. By the way, don´t use urea. Use sulfamic acid instead. Or if you cannot source any sulfamic, stick with copper precipitation.
Learn how to do things how they should be done. There are hardly any shortcuts in this business. And also, never pre-mix AR. Dose nitric acid incrementaly. You save precious nitric by doing so, and also it is much easier to process afterwards regarding excess nitric removal using sulfamic. Adding bases does nothing to the nitric or nitric residues.
Silver contamination is hardly a risk when using the HCl-bleach method to dissolve gold plated parts. Only some silver chloride will be produced if any silver is present, and only a fraction of a percent of it can dissolve in aqueous solutions.
Concentrated bleach is dirt-cheap too. A few bucks a gallon, enough to dissolve POUNDS of gold, since very little is added to the HCl at a time.
Read Hoke's Refining Precious Metals Wastes, it's all there and the book is a free download on the GRF site.
A lot of effort and time when into digitizing the Hoke's book, it's now available in several different formats.
Harold_V would have insisted that you read Hoke's before asking questions taking up members valuable time.
It now appears most of the newest members want to be spoon fed.
This is the chart Yggdrasil is referring too. as he mentioned copper will cement or react with metals below itself while those above will cement copper.
Take a look at iron, yes iron will cement all those metals below itself in the electromotive series.
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frugalrefiner has links to Hokes Refining Precious Metals Wastes, in his tagline.
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