Your take on this method for processing pins

[FiP]

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

 

[g_axelsson]

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

 

[patnor1011]

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

 

[Geo]

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.

 

[FiP]

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

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

 

[FiP]

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

 

[jason_recliner]

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

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

 

[FiP]

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

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

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

 

[upcyclist]

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)