Clean Copper from CuCl2 - while process went wrong

[Alentia]

Somehow I have derived clean no mess Copper from very strange process. I would appreciate some corrections and recommendation along the way.

Usually I process AMD Athlon brown fiber CPUs with the rest crappy ones in AP bucket. This time as I have received around 3lb of them, I have decided to go different route and make exact analysis of the yield.

1. AMD Athlon Fiber is no magnetic, so I figured I would process them with HNO3 and than AR in glass vessel.
2. After CPUs consumed 200ml of HNO3, pins had fallen off and with addition of bit more of HNO3 no reaction was going.
3. I have decanted copper nitrate, checked for silver (non present)
4. Washed off tin mud and proceeded to AR treatment

Next step I have decided to experiment with DI water, which I have added in.

5. HCL, HNO3 (100ml assuming there still were about 25 gr of copper or so and it was still there) - reaction was continuing for 2 days on low heat switching to medium heat for couple of hours a day
6. Result: dark red/brown solution. During the process I saw pins being dissolved and precipitated again. The way I understood the reaction later, HNO3 was used as catalist to create more and more CuCl.
7. I figured, no issue, will decant the CuCl liquid, refill with new AR, cleaner it will be.
8. After I have decanted solution I saw all my gold is caked in with CuCl2 at the bottom of vessel.
9. No worries, I though, will dissolve it with HCl and proceed to AR.
10. After using about 2L of HCL, CuCl2 still at the bottom and alot. I considered not to proceed to AR and keep dissolving CuCl2 in HCl is waste of acid.
11. Meantime, I was experimenting with first filter... I dropped it into the vision bowl, added bit of water, piece of Iron and few drops of H2SO4
12. I had witnessed of creation of clean copper out of CuCl2, while Iron was fizzling with escaping H2.
13. Now my dilemma, how to get rid of CuCl/CuCl2 from the vessel... I had a choice of running it through cheese cloth, but that would be too messy.
14. I have made a decision to convert all CuCl/CuCl2 in the vessel into clean copper and re-treat it later with HNO3
15. What I am not too sure about is how I am getting clean copper: HCl(little after washes) + CuCl2 + FeSO4 (Fe+H2SO4) = Cu + H2 +FeCl2(aq) + H2O + ?? not sure what happened with SO2 as I had only smelled H2, no sign of sulfur smell.

16. Searched google for CuCl2+FeSO4 looks like it is impossible reaction.

Can anyone make a sense of the above? and is there any other way to get rid of CuCl2 mud other then dissolving in HCl?

Copper looks very chunky and particles stick to each other. Liquid is clear. Will post pictures tomorrow.

 

[solar_plasma]

the CuCl liquid, refill with new AR, cleaner it will be.
8. After I have decanted solution I saw all my gold is caked in with CuCl2

CuCl...liquid??? and CuCl2...solid??? Shoudn't it be the other way round? I can't see a reason, why HNO3 or AR should REDUCE (=give electrons to) dissolved Cu(II) to pricipitate Cu(I). HNO3 and AR are oxidizers.

5. HCL, HNO3 (100ml assuming there still were about 25 gr of copper or so and it was still there) - reaction was continuing for 2 days on low heat switching to medium heat for couple of hours a day
6. Result: dark red/brown solution. During the process I saw pins being dissolved and precipitated again.

...better you had waited until ALL copper is dissolved in HNO3, before starting AR

wiki:

Alternativ bildet sich Kupfer(I)-chlorid beim Erhitzen von Kupfer(II)-chlorid mit metallischem Kupfer in konzentrierter Salzsäure als komplexe Säure H[CuCl2]. Beim Verdünnen der Lösung zerfällt sie unter Abspaltung von Salzsäure und Bildung eines weißen, schwerlöslichen Niederschlags von CuCl.

= if CuCl2 is heated with metallic copper and conc. HCl present, CuCl2 will form a complex: H[CuCl2]. After dilluting it decomposes to HCl and CuCl. Last one in a white, hardly soluble form.

Beside HCl as a solvant, it is said to be dissolvable in NH4OH, forming complexes. Wash carfully, so you do not have any precious metal ions in it, before adding NH4OH! Disclaimer: I have no experience with that, only read on wikipedia. So wait for what the others will say to that.

Though I would, if it were me, dillute it and add HCl and a little H2O2 3% (better just air) and in that way form CuCl2, which is soluble and can be used for AP:
http://en.wikipedia.org/wiki/Copper(II)_chloride#Co-catalyst_in_Wacker_process

4 CuCl + 4 HCl + O2 → 4 CuCl2 + 2 H2O

 

[solar_plasma]

Sorry, I edited, while thinking for hours over this problem. I have highlighted the conclusion, and I think it is the solution to the problem, with fat letters and underlined.

 

[solar_plasma]

I feel a bit uneasy and uncomfortable, possibly having solved a problem to one of our BIG players!

 

[Alentia]

I feel a bit uneasy and uncomfortable, possibly having solved a problem to one of our BIG players!

Thank you, Solar!

CuCl = white/grey sediment
CuCl2 = browish concentrated/green diluted HCl liquid

Adding H2O2 were seems like a possibility, but I did not want to take a risk to have gold dissolved even a tiny bit, as this would ruin the analysis.
I am not so versed in CuCl/CuCl2 process probably by reason it's requires lots of manual labor for little gain with washing and mess Copper Chloride creates. The process does produce results slow and surely. As long as it works, I did not want to go into much of the details.
I wish I have time to experiment more with it, but it seems like I have already started. What I do not know:

1. Adding H2O2 to CuCl, HCl and gold foils - will dissolve some gold, but how much? (I keep reusing my original solutions I have started over a year ago adding HCl and water when needed)
2. When H2O2 dissolves gold in Copper Chloride solution, how to recover it? Say it cements back in tiny particles into the CuCl mud, means it will be not economical to retrieve it from there for a very long time or ever. That would be like looking for a needle in haystack. How do you recognize gold in Copper Chloride vs dirt?

All of these cards, CPUs and other scrap contain lots of dirt, which you can not get rid of no matter how much you wash them before starting the process.

Correcting the formula:

HCl(little after washes) + CuCl + FeSO4 (Fe+H2SO4) = Cu + H2 +FeCl2(aq) + H2O + ?? not sure what happened with SO2 as I had only smelled H2, no sign of sulfur smell.

The question is, how and why did I get metallic copper?

 

[solar_plasma]

The normal method is to cement it out. I think I also read about SMB (though never tried). But I understand your arguments and in this special case it seems to me a good option to dissolve the well washed solids with NH4OH, which forms soluble complexes.

I am pretty sure this would work, but since this point is pure book knowledge, I hope some of the others will join in.

 

[solar_plasma]

But beware of gold ions in solution or silver in the solids, not to form any bad stuff.

 

[Alentia]

But beware of gold ions in solution or silver in the solids, not to form any bad stuff.

That is why I am not even looking at using HN4, even though it is an option.

I have attached picture showing precipitated copper in clean non mess solution when H2SO4 and Iron are added.

 

[solar_plasma]

I can fully understand this attitude. Though, if it IS CuCl and if it is washed well, there will not be any gold ion in it. Silver chloride would be dissolved, forming complexes, - one of our well known methods and I hope it is equally well know, it has to be made acidic again with HCl right after and it will pricipitate as AgCl again.

But you are absolutely correct in not doing anything, if you feel unsafe with it.


Just for the completeness of the record:

CuCl + 2 NH3 --> [Cu(NH3)2]Cl
and
CuCl + 4 NH3 --> [Cu(NH3)4]Cl

both are said to be colourless

at the air the [Cu(NH3)4]- will oxidize to blue [Cu(NH3)4]++


...but still, this is theory. We have seldomly to handle pure simple systems. I don't know what else effects the impurities will have.

 

[Alentia]

I am always looking at those things from at least 3 perspectives:

1. Cost of chemicals
2. Waste treatment
3. Safety

Using HN4 yields low scores on all 3 aspects.

Getting better wiki article on German wiki site, led me to read other wiki language articles in relation to CuCl. Here is reaction described on russian wiki, which seems to be reversed or not.
As well Russian article points to good solubility of CuCl in H2SO4 with no further explanations.

 

[solar_plasma]

1. Cost of chemicals
don't know, here they use it for professionally cleaning windows

2. Waste treatment
you'll be left with AgCl and NH4Cl, here commonly used in licorice

3. Safety
at least it is well described on the forum, better than experimenting, - for me to see

...i don't want to convince you, I am not in the position to do so, just my point of view

 

[chlaurite]

Adding H2O2 were seems like a possibility, but I did not want to take a risk to have gold dissolved even a tiny bit, as this would ruin the analysis.

Whoah there - When I read this earlier today, I originally thought you had separated out your gold from your waste between steps 4 and 5, and proceeded using only your waste from there.

If not, at step 5, you already lost (or at least, dissolved) your gold. HCL + HNO3 is Aqua Regia, which readily dissolves gold. What you have, then, amounts to an awful mess. Yes, you can technically use AR to process pins, but almost certainly not profitably (unless you have a good source for free nitric acid).

 

[Alentia]

Adding H2O2 were seems like a possibility, but I did not want to take a risk to have gold dissolved even a tiny bit, as this would ruin the analysis.

Whoah there - When I read this earlier today, I originally thought you had separated out your gold from your waste between steps 4 and 5, and proceeded using only your waste from there.

If not, at step 5, you already lost (or at least, dissolved) your gold. HCL + HNO3 is Aqua Regia, which readily dissolves gold. What you have, then, amounts to an awful mess. Yes, you can technically use AR to process pins, but almost certainly not profitably (unless you have a good source for free nitric acid).

Contrary I have no mess at all, everything is fine and dandy!

100ml of Nitric costs me about $0.35, not much of a loss here, but I have learned priceless lesson!

I have not lost a sinlge 0.01g of gold. It is currently safe in my vessel being separated by HNO3 from nice clean copper. As a matter of fact the gold is already very nice and clean in small specks sitting at the bottom of the vessel in copper nitrate solution, which I assume sizzling on low heat now. I did not waste a single chemical. 2l of HCL (CuCl2) went to my cards processing buckets. Three dissolved iron transformer plates and about 50ml of H2SO4 went to my waste treatment tank to raise pH.

I guess by mistake I have learned how to create clean copper from CuCl. Next time you think of disposing of your CuCl2/CuCl or dipping iron into it which creates the mess, save the liquid (for future pins) and drop few iron (transformer) plates with H2SO4 and convert your grey CuCl powder into clean copper, which can be reused later when cementing big batch of silver.

The only question remains unanswered what is the exact formula when converting CuCl to metallic copper with Fe and H2SO4?

 

[solar_plasma]

I would have expected the H2SO4 would drive out HCl, some HCl dissolved and some as vapors, depending on concentration and temperature. If so, the equation would be simple:

2CuCl + H2SO4 --> CuSO4 + 2HCl

then

CuSO4 + Fe --> Cu + FeSO4

since there (without heat) probably will be some HCl i solution, too, I guess there also will temporarily be a side reaction between CuCl and Fe, forming some iron(II)chloride, FeCl2.

Would be nice, if anyone could verify this. Btw: how can I type the oxidation stages into the equation, when writing on the forum?

 

[butcher]

For some reason I am having difficulty in following this thread, or making sense of it.

Ammonia to dissolve copper chloride would be a bad idea in my opinion, not only would it take a lot of ammonia but could form dangerous complexes with the other metals that can be involved.

HCl would be the best option to put CuCl back into solution as CuCl2.

But with nitrates involved this will also most likely put gold into solution, (as stated in the above post), if gold is not in solution now, just making a mess, out of this mess.

Putting what will go back into solution, back into solution the values can then be cemented out of solution with copper, leaving copper in solution, this may also put gold back into solution, because of nitrate salt which may be involved, deciding what is the best option depends a lot on what you have, how much you have and the state it is in, if there was a lot of these insoluble copper powders, with the little bit of gold powders, in this case I would look at another option.

Another option is add copper to cement anything of value that may be in solution now, if any powders form add these to those you already have, wash powders in a caustic soda water solution NaOH and wash salts formed out well with plenty of water washes, (the goal here is to convert the copper chloride to copper oxides/hydroxides, and wash out chlorides (NaCl formed), (at high temperatures of incineration chloride salts with gold powders can make the gold volatile as chlorine gas forms) dry the powders on low heat, and roast the powders to rid nitrates, previous acids, and oxidize the copper and base metal powders, and then proceed to wash out these base metals with acid, in order to start over to recover the gold from these powders.

I am still kind of at a loss as to what you have or where you are at.

 

[solar_plasma]

First time I do not agree with you, Richard

Have you seen, he said, he didn't dissolve all copper in his AR?

5. HCL, HNO3 (100ml assuming there still were about 25 gr of copper or so and it was still there)

All values should still be in the solids, - though denoxing a probe of the solution and stannous testing it would verify this.

I agree, the simplest should have been to put CuCl back in solution, forming CuCl2, - then cementing out any values (just to be sure). For some reason, which I did not understand, he was not able to dissolve the CuCl. Then the discussion came to other possibilities to dissolve it.

The main point for me is, WHY he got CuCl: because he heated with conc. HCl AND there was metallic copper present:

Solar_plasma:

wiki:

Alternativ bildet sich Kupfer(I)-chlorid beim Erhitzen von Kupfer(II)-chlorid mit metallischem Kupfer in konzentrierter Salzsäure als komplexe Säure H[CuCl2]. Beim Verdünnen der Lösung zerfällt sie unter Abspaltung von Salzsäure und Bildung eines weißen, schwerlöslichen Niederschlags von CuCl.

Translation:
= if CuCl2 is heated with metallic copper and conc. HCl present, CuCl2 will form a complex: H[CuCl2]. After dilluting it decomposes to HCl and CuCl. Last one in a white, hardly soluble form.

...

Though I would, if it were me, dillute it and add HCl and a little H2O2 3% (better just air) and in that way form CuCl2, which is soluble and can be used for AP:
http://en.wikipedia.org/wiki/Copper(II)_chloride#Co-catalyst_in_Wacker_process

4 CuCl + 4 HCl + O2 → 4 CuCl2 + 2 H2O

 

[Alentia]

For some reason I am having difficulty in following this thread, or making sense of it.

I was about to create mess, but created solution...

and Solar helped with equation. It all makes sense now. So basically clear liquid after copper precipitated from CuCl is mix of FeSO4 and FeCl2 and I got 2H2 driven off by both reactions. That explains no chlorine or SO2 smell.

 

[solar_plasma]

and I got 2H2 driven off by both reactions

That should be a third reaction:

Fe + H2SO4 (dill.) --> FeSO4 + H2

All three reactions take place at same time.

 

[Alentia]

Have you seen, he said, he didn't dissolve all copper in his AR?

5. HCL, HNO3 (100ml assuming there still were about 25 gr of copper or so and it was still there)

All values should still be in the solids, - though denoxing a probe of the solution and stannous testing it would verify this.

I agree, the simplest should have been to put CuCl back in solution, forming CuCl2, - then cementing out any values (just to be sure). For some reason, which I did not understand, he was not able to dissolve the CuCl. Then the discussion came to other possibilities to dissolve it.

1. After HNO3 treatment, there are still copper remained in pins (step #2 original posting)
2. All copper in step #5 (AR Treatment) not only dissolved, but converted into CuCl2, while HNO3 acted as catalyst.
3. Gold dissolved and precipitated again due to copper saturation. No values to cement.
4. The issue was to get rid of copper. Working with CuCl is hassle, so I had converted it to metallic copper with Fe and H2SO4 and restarted the process from step #1.

 

[solar_plasma]

4. The issue was to get rid of copper. Working with CuCl is hassle, so I had converted it to metallic copper with Fe and H2SO4 and restarted the process from step #1.

And it worked. Many roads lead to Rome, I would say.