Sulphuric Acid AP

[Marcel]

One of our members in the german forum for PM recovery has posted a tutorial on how to use sulphuric acid for AP.
Since there are many pictures and teh procedure is very similiar to HCl AP,, the language barrier will not be a problem.

Have a look at:
http://goldschrott.lefora.com/topic/19399780/03-Die-SchwefelsureAP?page=-1?page=-1#.UmQjsvl7J8E
Advantage:
HAP ( we call it Hot AP) based on sulphuric acid will not dissolve any gold, so you can speed up things by increasing temperature without losses at that point.

 

[FrugalRefiner]

Marcel,

This sounds similar to what spaceships mentioned in this thread: Final refining gold,-brainstorming.

Is this piranha or some variation, or is it a different process? Can you tell us what chemicals are being used and in what concentrations and quantities?

Dave

 

[Anonymous]

Dave it has nothing (absolutely nothing, not now, not ever) to do with what I was talking about Sir

Jon

 

[9kuuby9]

You basically made a "Piranha solution" or "Peroxomonoschwefelsäure" as they might say in Germany.

A typical mixture is 3:1 concentrated sulfuric acid to 30% hydrogen peroxide solution;

The resulting reaction it called Peroxymonosulfuric acid or Caro's acid

H2O2 + H2SO4 ⇌ H2SO5 + H2O

However do take note of it's Dangers; 8)

Pure Caro's acid is highly explosive. Explosions have been reported at various Universities. As with all strong oxidizing agents, peroxysulfuric acid should be kept away from organic compounds such as ethers and ketones because of its ability to peroxidize the compound, creating a highly unstable molecule such as acetone peroxide.

 

[9kuuby9]

Some visuals 8)

Dissolving copper in a Piranha solution.

[youtube]http://www.youtube.com/watch?v=L7xr6GqGnrw[/youtube]

 

[Anonymous]

Unless he has his labels mixed up he appears to be using 3 x H2O2 to 1 x H2SO4 there and then diluting it too?

 

[solar_plasma]

:lol: Here a bit more concentrated:
[youtube]http://www.youtube.com/watch?v=ihcA1bWzaoo[/youtube]

 

[niteliteone]

:lol: Here a bit more concentrated:
[youtube]http://www.youtube.com/watch?v=ihcA1bWzaoo[/youtube]

Now this video ""Makes the Point"" :shock:
Thanks Solar

 

[Palladium]

OHHHHHHH!!!!!! Were so sorry. You lost the laws of probability game. Thank you for playing and as a consolation prize you get a lifetime of pain and suffering and we are also going to throw in a free supply of humiliation and ridicule and while supplies last and if you can sign up, we are giving you free hospital and doctors visits under Obama Care!

 

[solar_plasma]

A bit off-topic, but anyway: I think it would be a sound experience also to see this video. Again a youtube-will-kill-you, what he is doing there and how he is doing it, is absolutely unworthy of discussion, no safety at all, on private ground, near to a street with opviously a lot traffic. Although it's about the reaction of AR with the very reactive zinc powder, it shows, how extreme those acids are able to act, if they are used uncorrect. When you have used chemicals a thousand times and never experienced them out of control, you might tend to feel they are more safe than they actually are and become incautious. I think this is in general, how our brain works, unless somebody gets occassionally safety trainings to prevent this routine thinking.

[youtube]http://www.youtube.com/watch?v=-S9w_40QJ9Q[/youtube]

 

[Marcel]

He used 12% H2O2 and 37% sulphuric acid/H2SO4.
First the pins are soaked in 20ml H2SO4 then the Peroxide (10ml) is dripped into the vessel.
Then he adds H2O2 until all gold has been removed from the pins. The whole process takes only a few minutes.
There is no more danger than with regular AP. Correct me, if I am wrong. I will try to translate the whole procedure later on.
The guy (godzilla) is a professional chemist, so he knows what he is doing.

 

[rickbb]

I think I'll stick to the AP process.

It may be slow, but at least it won't explode on me.

 

[Marcel]

I think I'll stick to the AP process.

It may be slow, but at least it won't explode on me.

I do not know why this discussion has gone a bit out of hands - nothing will explode here. This is simple battery acid that you can purchase in any walmart.

Those videos shown here have nothing to do with the acid/concentration beeing used.

The reaction is exotherm but not in a violentl way.
Pros are that you will not loose gold, because this AP will not dissolve gold. The remaining solution is even less critical than the HCl AP. (because there are no chloride beeing formed, which are very soluable in water and therefore toxic for plants and organisms).
It is also suitable for gold plated metal objects such as pins, whereby HCl AP is very slow and ineffective.
But I am not an evangelist for the method, just presenting it. I think godi has done a great job in researching and documenting this method.
I know the guy for some time now and he works very precise and clean and always documents every step aso.

EDIT: In the instructions it is cleary stated to incrementally add the Peroxide not to premix and then just dump the material in it. Just with AR you know it is important to use just the amount of chemicals needed and not to premix. So if you follow this procedure and use a flask with enough headroom ( which is also advised here) there is little danger of overfoaming. Not to speak of any of the other issues that are beeing brought up here.

 

[solar_plasma]

This is the concentration I have experiences with. You have to handle this very cautious and have to research everything about piranha solution to know, what could happen, - ofcourse he probably knows, what he is doing. It is much more exotherm then AP. AP is an old toothless sheep against that. Once again THIS IS NOT SULFURIC. It forms an extremely strong oxidizer PEROXOMONOSULFURIC. The reaction is completely different from AP=CuCl2.

If you would use this for the typical large amount of pins etc, it is something else, than if you use it on some gramms. Especially if you believe you can handle it comparable to AP. Even worse if anyone would get the bad idea to use it on trimmed fingers (DON'T!) - those contain organics. I don't know what will happen, but I also don't want to know it.

In order to prevent you get me wrong: I have great respect of you and this is no offence. This is just something I not only have read about (the read alone is scaring), but experienced: Using this acid for other purposes than it is commonly used, is like swimming with sharks.

If I can do something in 2 weeks of drop and forget without unusual dangers PLUS I can reuse it or the same thing in seconds with a very unforgiving process, - I take the first one.

And sulfates are mostly as bad as chlorides. Also insolubale heavy metal sulfates are mostly if not all very poisonous.

Those are only my few honest arguments. Read what the mods say about it in general http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=49&t=19424&start=20

It is amazing, yes. But, it's probably useless for us, when we look at the many cons and the few pros.

 

[Marcel]

Those are only my few honest arguments. Read what the mods say about it in general http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=49&t=19424&start=20

All I can tell from that thread is, it is the same point you are trying to make and again it is being missed. We are not talking about concentrated sulphuric acid, we are talking about battery acid at 37%. And it is not a premixed "piranha solution". The oxidizer is added in small increments. It gives one the impression, that you like to discuss, which is ok, but we should stay on topic.

 

[solar_plasma]

It's not the discussion in this point, I can have discussion everywhere and yes, I like good discussions.

It is very exotherm, that's why you use it very right slowly in small increments. I am afraid of someone believes it is like AP. Pure sulfuric into H2O2 including basemetals like you can pure it into HCl without harming yourself and you will have a hot surprise. Do it the other way round and it is even hotter.

What you don't understand is, also dilluted HCN is HCN and also dilluted peroxomonosulfuric is peroxomonosulfuric. Somebody stated the H2O2 would oxidise the copper and the sulfuric would react with the copper oxide, - like in AP. And, correct me, it is NOT! At least not only, since
H2SO5 + H2O <--> H2SO4 + H2O2 is a equilibrium.

Ofcourse a drop of KCN 0,1M is not as dangerous as a bottle of it, - but still it must be allowed to say, KCN is extremely hazardous. If I am the kill-joy then, it is ok for me, because it is no joy.

So, I have used it dilluted and I have seen its violence many times. If you don't believe, it's ok for me. I had to say it and I have done my human and social duty.

Let's get back to the interesting things.

 

[kkmonte]

I think I'll stick to the AP process.

It may be slow, but at least it won't explode on me.

Pros are that you will not loose gold, because this AP will not dissolve gold. The remaining solution is even less critical than the HCl AP.

If AP is done properly and you don't add too much oxidizer, then you will not dissolve gold either.

 

[butcher]

Copper II chloride leach, can be regenerated and reused to dissolve more copper, this not only makes the money we spend for chemicals go farther, but also lowers the waste we have to deal with.

At this point I see just see no real benefit in this process using sulfuric acid (sulfuric acid AP) to dissolve copper, over the methods I use now to dissolve copper.

I actually dissolve copper and recover the gold foils in a process that makes me nitric acid (I can use for other processes), and leaves a copper sulfate (I use in copper cells), this process requires distillation, but it works well and gives me byproducts I can use.

The copper chloride is slow when the copper is in more volume or thicker, but the leach has the benefit of being reusable, which lower the problem of having a waste solution to deal with.

Nitric acid or it poormans versions are quick to dissolve copper, and do a great job when needed.

 

[freechemist]

As far as I know, "sulfuric acid based AP" is not - and - will not be a valuable tool in separating base metals, especially copper, from gold and other PM's, because HCl is an equally essential constituent of a well functioning "AP-solution", like the copper(II)-ion, Cu²⁺, which forcedly has to be present, to dissolve metallic copper. This digestion-reaction can best be formulated as:

Cu(metal) + Cu²⁺ + 4 Cl^- ==> 2 [CuCl₂]^-

It leads to a solution, containing copper(I), stabilized and dissolved as an anionic chloro-complex-anion, [CuCl₂]^-. This anionic copper(I)-complex stays in equilibrium with copper(I)-chloride, CuCl, only very sparingly soluble in water, and rather high concentrations of free chloride-ions, from HCl, equally dissolved:

[CuCl₂]^- <==> CuCl + Cl^-

Solutions of copper(I)-ions in excessive aqueous HCl are easily oxidized by air to solutions of copper(II)-ions, hence the regenerability of "used-up AP-solutions" by bubbling air through them:

2 [CuCl₂]^- + O₂ + 4 H⁺ ==> 2 Cu²⁺ + 2 H₂O + 4 Cl^-

In contrast to aqueous HCl, aqueous sulfuric acid does not stabilize copper(I)-ions, and thus they are generated in only small amounts by reaction of metallic copper with dissolved copper(II)-ions. The link below leads to further information about copper(I)-sulfate, Cu₂SO₄.

http://copper.atomistry.com/cuprous_sulphate.html

 

[solar_plasma]

http://copper.atomistry.com/cuprous_sulphate.html

*LIKE!!!* Thanks for sharing!