How much metal will AR hold up ?

[samuel-a]

i have a few Kg of partially gold plated pins from motherboards (very low grade, about 0.1% gold by weight) that are not suitable for my stripping cell either by the size or the fact that the plated part is so small that i can't tell wether it had been stripped or not.

straight HCL on crock pot or AP will require huge amount of acid to completly dissolve. and just not practical...

now, i have been thinking about dissolving everything (pins) in AR + 30% H2O2 .
the pin are comprised of copper (98% +) nikel and gold, so probably when everything will dissolve the gold will ppt of the solution.

so... How much metal will 500 ml AR + 30% H2O2 will hold up at given temperature?



another option that i hade in mind for low grade stuff is to melt the pins and salvage the copper in a copper sulfate cell..

Thank you.

 

[Barren Realms 007]

You could melt it and pour into a thin slab and use it to drop silver fron nitric.

I would go with AP in a crock pot. Set it up to reclaim the copper by recover with steel and then bubble the reclaimed fluid and reuse to disolve some more copper. You can keep a continuous cycle with this approach with not as much new HCL needed.

 

[Harold_V]

i have a few Kg of partially gold plated pins from motherboards (very low grade, about 0.1% gold by weight) that are not suitable for my stripping cell either by the size or the fact that the plated part is so small that i can't tell wether it had been stripped or not.

straight HCL on crock pot or AP will require huge amount of acid to completly dissolve. and just not practical...

now, i have been thinking about dissolving everything (pins) in AR + 30% H2O2 .
the pin are comprised of copper (98% +) nikel and gold, so probably when everything will dissolve the gold will ppt of the solution.

so... How much metal will 500 ml AR + 30% H2O2 will hold up at given temperature?

I question your logic. In either case, you dissolve the pins completely. I do not recommend you dissolve gold along with base metals.

another option that i hade in mind for low grade stuff is to melt the pins and salvage the copper in a copper sulfate cell..

Bad idea. The presence of the huge amount of zinc (in the brass pins) will make the process fall flat on its face. In order to achieve success without endlessly changing electrolyte, the zinc would have to be eliminated in the melting process. That's not likely to happen, nor should one try without having the ability to control the zinc fumes, which can be lethal.

I took note that you suggest the pins are 98% copper. If that is true, you should be fine. Most pins are not copper, but yellow brass instead. Make sure yours are not yellow inside if you choose to part them after melting. Yellow brass us used in place of copper, so pins are more rigid. Pure copper is quite soft unless it has been well work hardened, or it is hardened by alloying, often with beryllium.

Harold

 

[Barren Realms 007]

Harold you mention the ability to control the zinc fumes. Many years ago I did a lot of welding on some galvanized coated pig crates.Woke up in the middle of the night blind as a bat. Made my way to the shower and took one, washed my eyes out and all was fine. Scary feeling and I don't recomend it.

 

[goldsilverpro]

Somewhere, I have a book with a photo of zinc "cobwebs" magnified 200X. They look like miniature thorn bushes and, as I understand it, they attach themselves to the inside of your lungs when you breathe them. They occur when zinc is overheated, whether in a melt or by welding galvanized steel. They are white, float in the air, and look like cobwebs. I've seen them produced several times. Maybe, Barren Realms eyes became coated with them.

Melted cadmium can produce the same type cobwebs, except they are red and even more dangerous. I produced them once when I melted some large silver contact points. Since then, I always dissolve points and cement the silver with copper, in order to eliminate the almost always present cadmium, before melting.

 

[leavemealone]

No matter how you slice it,Your best bet is to dissolve the pins in Hcl or Hcl + H2O2,assuming you cannot run them in a cell.Using AR you will have problems percipitating .1% Au from a saturated solution.Even if you force out by supersaturating by added copper,your powder will be extremely dirty,that is if the gold hasn't chemically fused with the copper in solution.In which case you will need to either drop everything with aluminum,tin,zinc....etc,or evaporate to powder and in both cases you will have to start from scratch.The gold content in most escrap is just too low to use AR.I have ran hundreds of batches of escrap in AR(I get material and chemicals free or very cheap) and I have had so many problems percipitating from a saturated AR solution.Its great for jewelry though.
Johnny

 

[Barren Realms 007]

Somewhere, I have a book with a photo of zinc "cobwebs" magnified 200X. They look like miniature thorn bushes and, as I understand it, they attach themselves to the inside of your lungs when you breathe them. They occur when zinc is overheated, whether in a melt or by welding galvanized steel. They are white, float in the air, and look like cobwebs. I've seen them produced several times. Maybe, Barren Realms eyes became coated with them.

Melted cadmium can produce the same type cobwebs, except they are red and even more dangerous. I produced them once when I melted some large silver contact points. Since then, I always dissolve points and cement the silver with copper, in order to eliminate the almost always present cadmium, before melting.

That could have been a possability, but I had no one there to look at my eyes at the time because I was alone. so whatever it was got washed out.

 

[samuel-a]

thenk you gentlemens for your insights.

i'm corrently using the process of recycled AP for the smaller pins where plated area to mass ratio is bigger.
1- a few dayes on crock pot 2- pour down the liquid and refill with new AP 3- let the flakes settle and filter.
the AP i regenerate with a fish tank bubbler .
but all and all this process is very long, and time consuming.
i'm planing on making a living out of refining and would like to deal also with the low grade as part of my rutine, therfor i'm looking for the most efficient way.


BTW, i have been trying on a miniscale the copper sulfate cell and it worked out pretty well.
the cathod cemented all of the copper to what seems to be pure copper sponge.
on the bottom of the tank thers left some powder and black flakes, i have confirmed that the gold was there.
and it seems that the electrolyte was fine... harold, how would zinc effect the electrolyte ?

 

[Harold_V]

i have confirmed that the gold was there.
and it seems that the electrolyte was fine... harold, how would zinc effect the electrolyte ?

You've already seen how. A well operating copper cell does NOT produce sponge, it produces copper nodules, which are rigidly attached to the cathode. The problem you'd have is copper sponge sloughing off and combining with the values, which you'd hope would accumulate in the bottom of the cell. I agree, the cell parts the copper, but it doesn't isolate the copper, entirely, from the values. I don't see much advantage there unless you can do so.

One thing you might consider is placing your anodes in a bag, but with sulfuric acid, you're going to have to use something that won't be destroyed by the acid. Common fabrics (cotton or wool) won't serve well at all. There are synthetic fabrics that are available from companies that sell filter media----you might try one of them to see if they have a thin material that will confine the particles that are liberated. Before you go to the trouble, however, I suggest you run the cell for a prolonger period of time, even if it mixes the copper with the values in the bottom. Get an idea of how long your electrolyte will hold up and perform as required. I think you're going to be rather unhappy with the results, but I'll be interested in reading your comments, either way. I could be wrong.

Harold

 

[samuel-a]

thank you harold for your opinion.

the copper sulfate solution is a 5% sulfuric acid and the rest is water, so i don't think it will not effect on a cloth, but , unlike a silver cell i'm gonna arrange the electrods horizontally , so i'll tray first to put a smaller vessel inside the cell under the anode to collect the debris.

just to be clear, the copper is cementing on the cathod without falling over, but it is cementing like a sponge.
i'll tray next with a sheet of copper rather then some copper coil.

i wonder what happens to the nickel... (?)

it will take me some time to get it complete on a larger scale...
i still need a larger crucible and a mold to pour the molten pins in to a thin plate or disk.


if it will go well i'll upload some guide... who know... mable it's simpler then we think... :mrgreen:

 

[Anonymous]

Nickel will stay in solution. what voltage are you using? I was doing the same but did not have my voltage low enough, seems when they refine copper they only use .30 volt or so if memory serves. Like Harold said you can bag the anode to catch the precious metals your silver and gold will be there.

Jim