# Your take on this method for processing pins



## FiP (Aug 31, 2015)

Hello to all,

I wanted to experiment a way of processing pins that would save some trouble with base metals.
I tried something and the current result seems OK.
Since it is slightly different i wanted to present it for all to comment and suggest to see if its worthwile, could be improved...

Here is what i did:
Very small experiment (6 or 8 pins)
1st: A bath of 30% hydrogen peroxyde for 1 week with shaking and leaving outside to sunlight in closed clear container.
2nd: emptying the spent Hydrogen peroxyde, allowing time to dry.
3rd: Second bath with copper chloride + fresh Hcl with regular shaking with same storage conditions as above

Results: on the third day (today) i have nice foils (seeing them move in solution show they are not too thin. All pins have lost their foils. 
See picture (i've pointed some foils, the remaining are under the pins or in solution).

I don't know if anyone has ever tried this, what problems they have encountered...
To separate pins from foils, i was thinking of keeping them stuck to the bottom by putting a strong magnet on the outside of the container bottom and normal rinsing and filtering.
If you have some ideas if this can work (or not) on a bigger scale (more than 8 pins :lol: ...) please feel free to share.

My best to all


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## Geo (Aug 31, 2015)

The process looks interesting. You might ask a moderator to change the thread name because texting lingo is against forum rules for safety reasons.


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## FiP (Aug 31, 2015)

Geo said:


> The process looks interesting. You might ask a moderator to change the thread name because texting lingo is against forum rules for safety reasons.


Thanks for that.
Will do


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## goldsilverpro (Aug 31, 2015)

> 1st: A bath of 30% hydrogen peroxyde for 1 week with shaking and leaving outside to sunlight in closed clear container.


Besides getting the pins wet and sort of cleaning them, what do you hope to accomplish with this?


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## FiP (Aug 31, 2015)

goldsilverpro said:


> > 1st: A bath of 30% hydrogen peroxyde for 1 week with shaking and leaving outside to sunlight in closed clear container.
> 
> 
> Besides getting the pins wet and sort of cleaning them, what do you hope to accomplish with this?


The idea which really was as a small scale test was to corrode the material (did some research on it) so that the acid would leech more easily since the problem for pins is too much base metals. After a week the base metal was strongly corroded (black, a bit coarse, sorry no picture). The gold was untouched. The goal of the 2 step process was to avoid gold to go in solution.
And off course as you said, after a while hydrogen peroxyde will decompose into water, but the high percentage could probably allow for a longer reaction time.

I don't know if the gold flakes came off because of only regular copper chloride and Hcl action or if the prior hydrogen peroxyde helped to lift them. The fast result made me think it had an effect. That's why i'd like to compare with what others have experienced to see whether the Hydrogen peroxyde played a role in it.
Any thoughts?

My bests


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## Geo (Aug 31, 2015)

I've used AP for about four years now and have not had any gold (that I could find later) dissolve. Unless you are adding peroxide continuously, copper(II) chloride doesn't dissolve gold.


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## FiP (Aug 31, 2015)

Geo said:


> I've used AP for about four years now and have not had any gold (that I could find later) dissolve. Unless you are adding peroxide continuously, copper(II) chloride doesn't dissolve gold.


Good point you are making. There seem to be no consensus on this. Some say it dissolves and others say the contrary.
I have a spent AP solution and i've put some copper to cement in it so i can test if any gold was lost in the process.

Apart from this point did you ever get flakes off from pins someway? I haven't stumbled on it yet. So i'm asking on the forum to see if the process i described above has any validity or could be done better in a different manner because flakes are easily recovered and processed.

Thanks

My bests 
(by the way the title seems to have been edited, thanks for telling me)


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## artart47 (Aug 31, 2015)

Hi ! 
I am curious! During the week in just H2O2 did the solution change color or was there any sign of a reaction occurring?
artart47


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## FiP (Sep 1, 2015)

artart47 said:


> Hi !
> I am curious! During the week in just H2O2 did the solution change color or was there any sign of a reaction occurring?
> artart47



Hello,

During the week there was no color change to the solution. I could observe some tiny fizzy bubbling (O2 probably) on the pins and they blackened over time. At the end of the week. The hydrogen peroxide was nearly all water but it still had very limited reactive strenght.

My bests


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## lanfear (Sep 1, 2015)

The advantage of digesting all the pins is that you are left with clean foils. On a big scale I think you will have a hard time separating foils and pins. The magnet could work to a degree, but you will always trap some gold. And not all pins are magnetic.


Jon


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## MarcoP (Sep 1, 2015)

I haven't researched yet the fact that H2O2 "corrodes" metals but surely [stt]out[/stt] it will be expensive and slower then AP. Values will go in solution only if you exaggerate with the peroxide as Geo's note. If properly used will not dissolve any value.

Marco


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## jason_recliner (Sep 1, 2015)

You can effectively do the same thing with already prepared, or reused, copper (ii) chloride leach. Not with "Acid / Peroxide" in the literal sense. I've done exactly that only weeks ago with one of several small batches of most likely Kovar tabs (wide, flat sort of pins), when I noticed they'd all given up their foils and I tried to shortcut their complete dissolution.

For me, it was the remaining heavy iron-like tabs staying as sediment while swirling then decanting the foils. The tabs stop moving pretty much immediately while the foils continue to "snow dome" for a while. It worked, but I had split the batch. Most foils remain in my decanted leach and a few stay with the tabs (heavy pins).

Then it's a matter of rinse and repeat. Literally. It takes a few additions of water and "snowdoming" to wash all the foils out.
I didn't think of a magnet. That would have helped.

It was then a matter of carefully decanting the leach off its foils and rejoining all the foils.

I share my experience as an example of something to probably best avoid. It's time consuming but it DOES work perfectly.
I agree, that it probably doesn't scale up very well.

Edit: My success was also likely due to the fact that my pins are very flat. Little square/round pins might not fare so well.


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## FiP (Sep 1, 2015)

MarcoP said:


> I haven't researched yet the fact that H2O2 "corrodes" metals but surely [stt]out[/stt] it will be expensive and slower then AP. Values will go in solution only if you exaggerate with the peroxide as Geo's note. If properly used will not dissolve any value.
> 
> Marco



I found a good few online articles mentioning the "corrosion" effect. If i remember well it was due to the action of the O2. And i think you are right it would be expensive to do it on purpose. I tried it because i have a jar that i started to use and have no other use for it now since i have plenty of copper chloride. The thing is that hydrogen peroxyde doesn't keep very well so i thought of this method as a way of using it before it is wasted, basically. I don' think (at present) using it as a first choice method would be wise economically speaking.

My bests


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## FiP (Sep 1, 2015)

jason_recliner said:


> You can effectively do the same thing with already prepared, or reused, copper (ii) chloride leach. Not with "Acid / Peroxide" in the literal sense. I've done exactly that only weeks ago with one of several small batches of most likely Kovar tabs (wide, flat sort of pins), when I noticed they'd all given up their foils and I tried to shortcut their complete dissolution.
> 
> For me, it was the remaining heavy iron-like tabs staying as sediment while swirling then decanting the foils. The tabs stop moving pretty much immediately while the foils continue to "snow dome" for a while. It worked, but I had split the batch. Most foils remain in my decanted leach and a few stay with the tabs (heavy pins).
> 
> ...



Thank you very much for this!
That's exactly the type of information i was looking for! It's helpful to know you had foils floating around without the use of hydrogen peroxyde. 
It seems that this process would be interesting then only if the pins are totally digested for easier processing.

I just looked at my pins and from yesterday's picture they are now half eaten up. Since i dealt with tiny sample quantities i'll leave them in solution untill they are completely digested for record sake. (note that the weather here is still warm and sunny). I'll keep you all posted.

My bests


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## jason_recliner (Sep 1, 2015)

Foils floating off a copper base is just the regular "AP" copper (ii) chloride process - poorly named as it is. The leach permeates the gold and attacks the underlying base metal. It's been covered half a million times.

Simplistically, copper solution begets copper solution, assuming enough free acid. Think of it like a sourdough bread "mother", my credit to Pantherlikher for that tip. I haven't added new peroxide to anything for over a year.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=8670&p=214923&hilit=artsy+stores+beer+glass+peroxide+once#p214923

If you add peroxide, you HAVE to dissolve all your base metal. Otherwise any prematurely dissolved gold could be cemented powder and you can lose it.

Now in my case, with assumed Kovar pins, the more green-tea than emerald colour is consistent with my leach heading more towards something ferrous than cupric. It kind of ruins the leach, at least in my experience.

If you have a very large volume of pins, there are better ways to handle it than leaching. The sulphuric cell is more efficient and creates less waste. It is also a less forgiving chemical than chloride leach. Personally I have not had great success yet gaining concentrated H2SO4 so I have stick to slow leaching. YMMV.


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## FiP (Sep 2, 2015)

Hello to all,

Just a quick update:
Today the pins are completely gone.
The foils are intact. 
No powder or sediments at the bottom.
Solution color is a mix of emerald and ferric (black brownish) like before but darker.

My bests


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## jason_recliner (Sep 2, 2015)

That colour is characteristic. If you were to add oxygen, through a fish bubbler, you'd likely find it turn green again.
As long as there is any undissolved base metal, that metal will keep using up the free CuCl2 and keeping your solution dark.
So my recent take on this is that it's only after it finally turns green - and is oxygenating again - that you can be really sure all base metal is dissolved.


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## FiP (Sep 2, 2015)

jason_recliner said:


> That colour is characteristic. If you were to add oxygen, through a fish bubbler, you'd likely find it turn green again.
> As long as there is any undissolved base metal, that metal will keep using up the free CuCl2 and keeping your solution dark.
> So my recent take on this is that it's only after it finally turns green - and is oxygenating again - that you can be really sure all base metal is dissolved.



Thanks for that
I'm not so sure about this aspect since i have cemented some solutions and with copper tubing in them they went completely clear (see through green), and when i took it out it went dark again... Maybe it has something to do with exposure to light?

My bests


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## bswartzwelder (Sep 2, 2015)

When using HCl and H2O2 to form a copper II chloride leech (AP), if you use H2O2 greater than the 3% strength, the chance of dissolving gold increases. The higher the strength of the H2O2, the higher will be the chance of gold dissolving. Using the 3% found in most grocery stores, WalMarts, etc., should be fine. Also remember that you only need a tiny amount to get the reaction started. I'm pretty sure I have read where some people have used a gallon of HCl and 1/2 gallon of H2O2. THAT'S WAY TOO MUCH H2O2! For a gallon of HCl, a cup of H2O2 is plenty. Even less will do. Also, you will not cement copper out of a copper II chloride solution by using copper. All you will manage to do is dissolve the copper you were trying to cement the original copper in the solution to. You cement out the copper in solution by using scrap steel. I have successfully used angle iron, but others on the forum recommend using old transformer laminations.


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## FiP (Sep 2, 2015)

bswartzwelder said:


> When using HCl and H2O2 to form a copper II chloride leech (AP), if you use H2O2 greater than the 3% strength, the chance of dissolving gold increases. The higher the strength of the H2O2, the higher will be the chance of gold dissolving. Using the 3% found in most grocery stores, WalMarts, etc., should be fine. Also remember that you only need a tiny amount to get the reaction started. I'm pretty sure I have read where some people have used a gallon of HCl and 1/2 gallon of H2O2. THAT'S WAY TOO MUCH H2O2! For a gallon of HCl, a cup of H2O2 is plenty. Even less will do. Also, you will not cement copper out of a copper II chloride solution by using copper. All you will manage to do is dissolve the copper you were trying to cement the original copper in the solution to. You cement out the copper in solution by using scrap steel. I have successfully used angle iron, but others on the forum recommend using old transformer laminations.



Thank you for this answer.
As i was discussing with Geo that's the problem with AP some say you can dissolve gold some say you can't...
That's why i tried to cement gold out of an old AP solution giving it copper and i got black cementation around it which i haven't recovered and tested yet (to see whether it's gold or not). (But i've cemented gold successfully with copper before out of a nitrate solution, unless i'm mistaken it looks that chemistry should be the same).
I was previously answering a post about the possibility of losing gold in a powdered sediment form if the solution doesn't go clear. I just shared what i have seen (i'm much less experienced though). I found it interesting that when i took out my copper out of the AP waste solution (that i was trying to cement to see if any lost gold would show up) the solution got dark again when the solid copper was removed. You could see through it before, it just had a light green color and once the copper was removed, it went black (meaning you can't see through it but if you look at drops, it's still green though). This for me showed that copper chloride solution going clear is not necessarily a sign that all base metals are dissolved.
By the way i still have some of that solution in 2 different vessels (one dark where the solid copper copper was removed and one clear where the solid copper remained and a small amount of hcl was added to create fresh copper chloride leaching solutions which i've used succefully so the volume left is reduced).
Indeed chemistry has its mysteries but being curious and investigating (safely off course) makes it really interesting and enjoyable. I'm really intrigued by this color change my thinking goes towards some interaction with light that is prevented when solid copper is in solution, but it's only a gut so if anybody knows more, that would be interesting to hear.

As regards the process i was trying, the pins completely dissolved in copper chloride in 3 days in warm (not hot) weather. The pins where the type you find on the power supply for HDD, they came out an old power pc mac, i tried these because they were the bigger i had on my hands at the time i initiated this small experiment.
Anybody feels it improved speed (one week in hydrogen peroxyde 30% and then 3 days in copper chloride + fresh HCl)? Or it's just normal (3 days then).
I'm getting a batch of pins ready at present, i'm still wondering whether i will do it the regular chemical way (CuCl) or try this method again weighing, timing and all... To keep moving forward while i'm working on my cell.

Thank you to all for your feedback, help and interest.
My best to all and to you bswartzwelder off course


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## jason_recliner (Sep 2, 2015)

You're talking about two different processes. Dissolving base metals in copper chloride leach, or cementing gold out of solution using copper metal. Both can happen together, but they are different. Let me see if I can explain.

In the former, your "AP" leach will be dark as long as there is copper left to dissolve. Air pumped into it will help keep it trending to green, but the copper will keep pushing it to black. Given my personal setups, it's a battle copper generally wins. Once the last of the copper (or other base metal) is dissolved, the black effort stops and the green effort takes over. CuCl2 leach, itself, will not dissolve your gold.

But! If you initially added H2O2, some gold may (will) have been dissolved and will quickly cement out again once it comes across some copper. So you need to dissolve all base metal, then you are left with foils and a little brown dirt, which is also gold.


The other, entirely different, process you mentioned is cementing gold, where you add solid copper bar to a solution of gold. You don't do this with pins in leach.
The copper replaces gold in solution. As the copper dissolves, you'll see it turn darker as the copper dissolves faster than it only cements copper. If you have agitation, and again an air bubbler is good for this, the process will go faster. The aim is not to dissolve all the copper, but to determine when the gold is removed from solution. It stops building up on the copper as powder. Then a stannous chloride test tells you for sure.


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## FiP (Sep 3, 2015)

jason_recliner said:


> You're talking about two different processes. Dissolving base metals in copper chloride leach, or cementing gold out of solution using copper metal. Both can happen together, but they are different. Let me see if I can explain.
> 
> In the former, your "AP" leach will be dark as long as there is copper left to dissolve. Air pumped into it will help keep it trending to green, but the copper will keep pushing it to black. Given my personal setups, it's a battle copper generally wins. Once the last of the copper (or other base metal) is dissolved, the black effort stops and the green effort takes over. CuCl2 leach, itself, will not dissolve your gold.
> 
> ...



Thank you for this answer!
All this seems to make sense, thanks.
For continuity sake, if i have questions or obseravtions regarding cementation, i'll move these to another section in the forum.
I'll just get back to the process i was asking for feedback upon
My bests


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## FiP (Sep 3, 2015)

FiP said:


> Here is what i did:
> Very small experiment (6 or 8 pins)
> 1st: A bath of 30% hydrogen peroxyde for 1 week with shaking and leaving outside to sunlight in closed clear container.
> 2nd: emptying the spent Hydrogen peroxyde, allowing time to dry.
> ...



And 2 days later all the base metals had dissolved.

So in all it took around 12 days (7 days in H2O2 30% + 5 days in CuCl+HCl) to dissolve all base metals. 
The results gave only floating foils and no sediments or dirt at the bottom.

The quantities recovered are too tiny to get tested and weighed.
As this method doesn't mix H2O2 and CuCl HCl, it's not AP. 

For those who have experience using AP on pins does this look average speed or does it look fast? Just for comparison.

Thank you to all to let me know what you think.

I'm thinking to do a 100 g batch with this process and record and weigh everything to see if it's worthwile.

I have a batch of mixed pins from boards, IDE, and mobile phones. Anyone has an idea of an average yield to be expected?

My bests to all


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## g_axelsson (Sep 3, 2015)

Even if you don't mix hydrochloric acid and hydrogen peroxide it's still the process that's called AP. It's just a bad name on a process that should be called the copper chloride process.

Göran


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## jason_recliner (Sep 4, 2015)

FiP said:


> So in all it took around 12 days (7 days in H2O2 30% + 5 days in CuCl+HCl) to dissolve all base metals.
> The results gave only floating foils and no sediments or dirt at the bottom.
> ...
> For those who have experience using AP on pins does this look average speed or does it look fast? Just for comparison.


It's my opinion that this is about normal, considering the batch. It's faster than mine, but though you didn't have an air bubbler, you also had a unusually low ratio of volume to surface area; this would take on oxygen quite well.

I don't really think your peroxide pre-processing added anything. If you want to be sure, just for science sake, run a control test identically in every way except the peroxide. Or preferably two new tests, with the CuCl2 leaching done side by side.


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## FiP (Sep 4, 2015)

jason_recliner said:


> FiP said:
> 
> 
> > So in all it took around 12 days (7 days in H2O2 30% + 5 days in CuCl+HCl) to dissolve all base metals.
> ...



Hello,

This seems to make a lot of sense! Low ratio volume to surface area could explain this very well.
And making 2 tests with the same set up seems to be a wise way to know for sure.

Thanks for your help and input.

My bests


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## FiP (Jan 11, 2016)

FiP said:


> jason_recliner said:
> 
> 
> > That colour is characteristic. If you were to add oxygen, through a fish bubbler, you'd likely find it turn green again.
> ...



Hello Jason,

I found this aspect interesting so i tried to investigate and experiment.
I asked around but got no proper explanation.

In my experiment i did this: take some green CuCl2 solution. Added some copper to it. After some time it got clear (no color at all). I removed some of the solution to a clear, empty, container. I could then observe from the surface of the solution that it started to get a green colour.
My conclusions: when "saturated" with copper, a solution turns clear.
Contact (or maybe forced contact with air (probably O2)) will bring the colour back (green).

As to the use of a CuCl solution with that much copper in it, i found it to be less reactive: to get it to leech to a "normal expected rate" it needs to be combined with a consequent amount of fresh HCl.

These were my findings, where are at you a with this?
If anyone has any light to shed on this, i'm eager!

Best to all!


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## jason_recliner (Jan 11, 2016)

In my experience, the typical behaviour of CuCl2 is that if you add more copper metal it will turn from green to a very dark brown.

But one of my early errors was to throw everything I had into a pickle jar of acid. There, I noticed a distinctive stratification; a completely clear layer under the dark brown layer. This clear layer was likely saturated with zinc or tin or something else more reactive than copper. Could this be happening to you?


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## goldsilverpro (Jan 11, 2016)

FiP said:


> FiP said:
> 
> 
> > jason_recliner said:
> ...


You didn't think this out very well. Did you notice any whitish powder?

The solubility of CuCl2 in water (~700g/l) is about 11,000 times greater than the solubility of CuCl in water (~.06g/l). Were you to add solid white CuCl to water, the solution (super weak - .06g/l) would be essentially colorless. CuCl will dissolve in free HCl, forming the green CuCl2. The Cu you added to the CuCl2 reduced the CuCl2 to CuCl and that's why it cleared up - most all of the CuCl precipitated.

In a wrong way, you are right. The copper, as CuCl, was "saturated" in the clear solution. However, it would take ~6 gallons of water to dissolve 1 gram of Cu, as CuCl. Were you to "saturate" water with the yellow CuCl2, it would pick up a couple of waters of hydration and become, in solution, the green CuCl2.2H20. If you crystallized this out gently, you would likely have green CuCl2.2H2O crystals. In that case, at saturation, 6 gallons of water would contain ~41 pounds of copper. When Jason added copper, it might have reduced the Cu-2 further than Cu-1 to Cu metal powder, which is a reddish-brown color. Note that red and green make brown.


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## g_axelsson (Jan 11, 2016)

goldsilverpro said:


> FiP said:
> 
> 
> > FiP said:
> ...


I'm with GSP on this, just one slight detail I'm objecting to and would like to expand on...

CuCl will dissolve in free HCl, forming the green CuCl2 when you have excess oxygen. When you are in an oxygen free environment it only complexes with the chloride ions and usually forms the brown CuCl in solution.
Your initial dissolving of the copper tube gave you CuCl that used up the oxygen in the solution to form more CuCl2, that dissolved more copper until the supply of oxygen and CuCl2 was depleted and the dissolving halted.
When you put it in a separate beaker the oxygen from the air diffusing into solution turned the small amout of CuCl into CuCl2 when it reacted with the oxygen, giving the green color.

Fip, if you have had a lot more HCl in solution it would have turned brown instead of clear. Then done the transformation into a much more deeper green when sitting in a separate beaker as there would have been a lot more copper in solution. Just like your initial observations when removing the bubbler turned the solution dark.

Göran


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## goldsilverpro (Jan 11, 2016)

Goran,



> CuCl will dissolve in free HCl, forming the green CuCl2 when you have excess oxygen. When you are in an oxygen free environment it only complexes with the chloride ions and usually forms the brown CuCl in solution.


I disagree.

CuCl2 is yellow, not green. Only the hydrated form is green. I can't see how oxygen enters into it. CuCl isn't brown unless it's contaminated with something like copper powder or dirt. CuCl is white. It's been awhile but, when you add an excess of SMB to an AR soln, you often get an off-white (white plus dirt probably, CuCl precipitation.

I will edit my first post to correctly read: forming the green CuCl2.H20 (in place of CuCl2). CuCl2 is yellow. 

The compounds, colors, and solubilities all came from the CRC Handbook. This book is about the "last word". In that book, white always means white, yellow means yellow and green means green - not, for example, off-white, brown, and blue-green.

EDIT: I found this interesting. I just read that, with concentrated HCl and a little potassium chlorate, copper turnings are dissolved, forming a black solution at first, which ultimately becomes completely colorless. On dilution, the salt precipitates as the snow-white pure CuCl, which turns greenish in moist air (CuCl2.H2O). In other words, CuCl is fairly soluble in concentrated (only) HCl. Reminds me of Lou's HCl, AgCl removal from Au powder method, sort of.


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## g_axelsson (Jan 11, 2016)

goldsilverpro said:


> Goran,
> 
> 
> 
> ...


I won't argue against CRC, that's a good book...
...but I would assume that CuCl2 in solution is quite hydrated. :mrgreen: 

Oxygen enters into the equation as...
4 CuCl + 4 HCl +O2 = 4 CuCl2 + 2 H2O
You need something to take the excess H or the copper wouldn't go from +1 to +2 oxidation state. That's why people uses a bubbler to oxygenate copper chloride leach.

Precipitated (solid) CuCl is white. The color of CuCl in solution, when complexed with a high Cl- ion solution is dark brown as can be seen when running low on oxygen. If enough CuCl goes into solution some is oxidized into CuCl2 but when the oxygen is gone it is starting to color the solution dark brown / black.
Since you only need a lot of Cl-, even saturated NaCl solution will dissolve quite a lot CuCl. So basically a strong CuCl2 should be able to dissolve a lot of CuCl too.

But I agree, in pure water the solubility of CuCl is very low. It can be seen when you have a dark brown solution close to saturation and add a bit of water. That precipitates a cloud of white CuCl.

The effect of CuCl in the CuCl2 can be seen in the document on Lazersteve's site.
http://www.goldrecovery.us/%5Cgoldrecovery%5Cdocuments%5CCuCl.pdf (login is required)
On page 10 there is a nice series of concentrations, showing the color change.

Göran


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## goldsilverpro (Jan 11, 2016)

According to this article
http://www.rsc.org/suppdata/ta/c2/c2ta00138a/c2ta00138a.pdf

the CuCl complexes with the HCl according to the following equation
CuCl + xHCl = HxCuCl1+x, Where x is 1 or 2, HCuCL2 or H2CuCl3

That's where the H goes. No oxygen involved. You're right, though, in that oxygen is required if you want to produce CuCl2 (actually CuCl2.H2O) from CuCl in the presence of HCl.

The more I look at this, the more I think we're approaching this from 2 totally different angles. Sort of like apples and oranges.


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## g_axelsson (Jan 11, 2016)

goldsilverpro said:


> According to this article
> http://www.rsc.org/suppdata/ta/c2/c2ta00138a/c2ta00138a.pdf
> 
> the CuCl complexes with the HCl according to the following equation
> ...


But that's still only CuCl + HCl in a complex, you posted CuCl2 above and to get to that oxidation state you need an oxidizer. Most people here use oxygen or peroxide (but you could also use Cl2). You need to keep track of the oxidation state of that copper atom.


goldsilverpro said:


> CRC says that CuCl is soluble in HCl (or NH4OH), not HCl + O2. If oxygen were required, it would have said so.


I never said you needed oxygen to dissolve CuCl. The oxygen is used for turning CuCl into CuCl2 in the step that refreshes the leach to be able to dissolve more metallic copper. The only thing needed to dissolve CuCl is a solution rich in free Cl- so even concentrated NaCl can do it. This I have tried and it worked, but HCl is more effective.

If the only step needed to turn CuCl into CuCl2 is addition of HCl we would get a reduction of the H+ to balance the oxidation of copper. That would release H2 as gas and I've never seen that happen. We need an additional oxidizer for that step, CuCl and HCl doesn't have enough energy to do that by themselves.

Göran


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## goldsilverpro (Jan 11, 2016)

I finally see what you were saying about my statement of CuCl + HCl = CuCl2. I erred and will correct it. 

What is brown CuCl?


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## g_axelsson (Jan 11, 2016)

goldsilverpro said:


> I finally see what you were saying about my statement of CuCl + HCl = CuCl2. I erred and will correct it.
> 
> What is brown CuCl?


Then we are on the same page.

Did you have a look at the copperchloride document on Lazersteve's site?
This is the picture on page 10 that I was talking about.



That document is for copper chloride etching what Hoke is for refining. It doesn't tell you exactly what you need but gives enough background for you to understand what is happening.
First time you read it you probably don't recognize what it tells you, but coming back to it while experimenting and suddenly you get it, how good it actually is.

Göran


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## FiP (Jan 11, 2016)

Hi,

I thank you all for having taken the time to expand on that and shared the knowledge.
I'm still curious about one aspect: i see that when i remove solid copper from the clear solution, it goes back to green-brown. Anybody knows why, i found that funny.

My bests


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## g_axelsson (Jan 11, 2016)

FiP said:


> Hi,
> 
> I thank you all for having taken the time to expand on that and shared the knowledge.
> I'm still curious about one aspect: i see that when i remove solid copper from the clear solution, it goes back to green-brown. Anybody knows why, i found that funny.
> ...


When you have a copper tube in it, all CuCl2 is used up dissolving copper. In solution is only CuCl. Oxygen is depleted by oxidizing CuCl into CuCl2 but dissolving copper stops the CuCl2 to build up.

When you remove the tube the oxygen oxidizes CuCl into CuCl2 and the CuCl2 starts to build up, which you see as a change in color.

Göran


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## FiP (Jan 11, 2016)

g_axelsson said:


> FiP said:
> 
> 
> > Hi,
> ...



Thanks,

Following the reasoning from above posts, i understand.
With the solid copper in, my solution has vitually no color though.

FiP


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## goldsilverpro (Jan 11, 2016)

I have a copy of the article that Goran mentioned (CuCl.pdf) and have posted it here, along with 2 other articles in my files.

I have never used the AP method (or even played around with it) and probably never will, at least as long as I can buy cyanide (1st choice, without a doubt). With no cyanide, I would probably buy a barrel plater (tumbler) and use the sulfuric stripper (2nd choice) or nitric (3rd or 4th choice). I might even give a KI/I2 or KBr/Br2 stripper a shot. I find it hard to even consider a process if I don't think it will be profitable on a large scale.


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## FiP (Jan 11, 2016)

I see many of you are active on the forum, so i’ll take the opportunity to share with you on the subject this thread was opened about.
Some of it will have more meaning to you than to me, so I look forward to your comments.

Here is what I did and observed:
I was advised to try two sets of identical pins for comparison. So I did.
2 identical glass containers with about 100 g of non-shaved pins.

Container A: 1st step: bath with 30% hydrogen peroxide until covered. It triggered a reaction (surprisingly): generated heat (real hot), no fumes just regular fizz, the solution became cloudy (white mainly, tint of grey-blue). It left a grey powder at the bottom. I then siphoned all the liquid when the reaction was over. Pins were blackened.
I then added my copper chloride to each containers to the same level.
I left it for a long time and then drained completely the containers to look at the pins and those that bathed in hydrogen peroxide were showing signs of a more advanced dissolution.

I decided to add hydrogen peroxide again to test if it would help again. Be advised: this step is dangerous (mask, gloves ,glassed, shield, armor, helmet… :mrgreen: ) I tried it with caution and it was wise. The reaction is very violent, can spatter high and far, generates heat and fumes. So by very small controlled increments, I got both containers this time filled to above the pins with hydrogen peroxide. The solution was slightly cloudy again.
I then drained again the hydrogen peroxide and added again my copper chloride solution.

I checked again after a while and could see that the pins that were started with hydrogen peroxide were far more dissolved.
I did the hydrogen peroxide bath one last time for both and the copper chloride again.
In all the processes the gold foils looked good and remained in a healthy shape down to the end.

I saw the work advancing faster due to the start with hydrogen peroxide. I tried it since I want to use my hydrogen peroxide before it loses its strength and since I have copper chloride made I don’t use it and I have no intention to bleach my hair or fire a rocket with it… I understand moneywise, doing it on purpose might not be the best choice. If one have time to wait for pins to dissolve, the time gained with this will only be a few weeks. But since we all have some hydrogen peroxide lying around, if used appropriately and safely, it may serve some new purposes.

Look forward to hear your comments and get down to the chemical principles behind this if anyone knows.
My bests,
FiP


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## g_axelsson (Jan 11, 2016)

What's "non-shaved" pins?

What was the base metal?

Fizzing when adding H2O2 probably means it is breaking down. Silver for example works like a catalyze to break down H2O2 into H2O and O2.

In your first post you mentioned storing the mix in a closed container... copper chloride etch needs oxygen to work. Try copper chloride etch with and without a bubbler and I think you will learn something useful.

All I see is a wild experimenting without any plan or expectation of what should happen.

Göran


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## patnor1011 (Jan 11, 2016)

Not to mention that 30% strong peroxide is way *too* strong and will dissolve some of the gold, which you then washed/poured away.


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## Geo (Jan 11, 2016)

The dissolved gold would not still be aqueous by the time all the copper has been dissolve. As long there is solid metal remaining when the oxidizer is depleted, any dissolved gold will cement out of solution. The problem is that anyone inexperienced will toss the cemented gold powder not knowing what it is.


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## FiP (Jan 12, 2016)

g_axelsson said:


> What's "non-shaved" pins?
> 
> What was the base metal?
> 
> ...



Thanks,

No closed containers when solutions used.
I read a bit before starting this, H2O2 in contact with metal will break down and release H2 and H2O is the resulting byproduct left in the container.
I had tried the experiment on a very small scale and it had helped with dissolving the pins.

The pins are a mix coming from different sources (ide, scsi, etc...). I wanted to have a general view with many types of metal.

Cheers


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## FiP (Jan 12, 2016)

patnor1011 said:


> Not to mention that 30% strong peroxide is way *too* strong and will dissolve some of the gold, which you then washed/poured away.



Is it really possible that H2O2 alone will dissolve gold even at high concentrations. When i studied it (i'm not expert but i checked) the way H2O2 will act on a metal is by corroding (and i really mean corrosion) it through the use of O2. So if a metal does not corrode with air and moisture, it seems unlikely it will react to H2O2. But i may be wrong, 

Cheers


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## jason_recliner (Jan 12, 2016)

FiP said:


> patnor1011 said:
> 
> 
> > Not to mention that 30% strong peroxide is way *too* strong and will dissolve some of the gold, which you then washed/poured away.
> ...


Your material is not in H2O2 alone. It's in a copper chloride leach with a powerful oxidiser.


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## FiP (Jan 12, 2016)

jason_recliner said:


> FiP said:
> 
> 
> > patnor1011 said:
> ...



Thanks,

I just reexplain the process:
1-dry pins + H2O2This step alone generated heat and already started to corrode the pins (i mean corrode) and they got black (see above post)
2-syphon liquid (H2O left from H2O2) then add leach.

Then i did emptied out the leach and refilled with fresh H2O2 later. The leach could have left ions behind but the H2O2 leaves only water (added to whatever was there off-course).

So there are actually two different reactions: one where H2O2 is added to dry pins that haven't been exposed to any chemical process yet. And another where H2O2 is added to pin that have already been leaching in copper chloride.

What i would like is to understand the chemistry of the reactions i observed, like for the posts that explained CuCl and CuCl2 above.

Take care,

FiP


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## upcyclist (Jan 12, 2016)

Hydrogen peroxide also bubbles when you apply it to a wound on your skin, right? (Though hopefully you'd never use 30% peroxide for that!)

Just from your experiments, all you can say is that the hydrogen peroxide is reacting with something on your pins. Probably the metal, but that all depends on how much you've controlled the pins' environment and if they're clean. Do they still have acid on them from a previous trial? Do they have Big Mac grease on them? Do they still have solder on them? How do you know?

In the second step, you don't say if you washed/roasted/dried the pins before applying acid. If you didn't, you're essentially using the AP (acid/peroxide) method, kickstarting the copper chloride etch process with a strong oxidizer. That is why so many of the people (and possibly all the experienced ones) on this forum use a bubbler--it too provides the oxygen needed for the etch process, and given that 30% H2O2 is pretty nasty, why use it throughout the process if you don't have to?

Also, if you didn't try to remove the AP before adding your acid, and you were just "experimenting", that again makes me wonder what else might be on your pins, which brings me back to the "probably the metal" comment 
_
(edit: just the subscripts)_


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