# Sulphuric Acid AP



## Marcel (Oct 20, 2013)

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.


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## FrugalRefiner (Oct 20, 2013)

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


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## Anonymous (Oct 20, 2013)

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

Jon


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## 9kuuby9 (Oct 20, 2013)

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.


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## 9kuuby9 (Oct 20, 2013)

Some visuals 8) 

Dissolving copper in a Piranha solution.

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


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## Anonymous (Oct 20, 2013)

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?


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## solar_plasma (Oct 20, 2013)

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


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## niteliteone (Oct 20, 2013)

solar_plasma said:


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



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


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## Palladium (Oct 21, 2013)

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!


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## solar_plasma (Oct 21, 2013)

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]


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## Marcel (Oct 21, 2013)

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.


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## rickbb (Oct 21, 2013)

I think I'll stick to the AP process.  

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


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## Marcel (Oct 21, 2013)

rickbb said:


> 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.


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## solar_plasma (Oct 21, 2013)

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.


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## Marcel (Oct 21, 2013)

solar_plasma said:


> 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.


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## solar_plasma (Oct 21, 2013)

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.


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## kkmonte (Oct 21, 2013)

Marcel said:


> rickbb said:
> 
> 
> > I think I'll stick to the AP process.
> ...



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


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## butcher (Oct 21, 2013)

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.


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## freechemist (Oct 23, 2013)

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


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## solar_plasma (Oct 23, 2013)

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




*LIKE!!!*  Thanks for sharing!


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## chlaurite (Oct 23, 2013)

No doubt I'll get told off for even suggesting this, but I have to wonder...

Would a *very dilute* version of this work to eat away epoxy? I don't mean anything fast, I mean really, really dilute, something we could let soak for a few days?

I know they use this in the lab to clean organic residues off of glassware, but I can't find any references to using it either in a weaker form or on more than trace amounts of such residues.


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## niteliteone (Oct 23, 2013)

chlaurite said:


> No doubt I'll get told off for even suggesting this, but I have to wonder...
> 
> Would a *very dilute* version of this work to eat away epoxy? I don't mean anything fast, I mean really, really dilute, something we could let soak for a few days?
> 
> I know they use this in the lab to clean organic residues off of glassware, but I can't find any references to using it either in a weaker form or on more than trace amounts of such residues.


Well we have discussed "wet ashing" before, where we decided as a group that this was not a process to promote due to the inherent dangers of working with hot sulfuric acid.
So you're not to far off in questioning this as an alternative. Just don't know how it will go over with the masses and how would the newbies react :?: 
Would newbies actually learn what they are doing before they think they can do it :?: 
Or do as they usually do and just jump in, and end up with another mess, or worse.

That's something we must keep in mind when discussing processes of any kind. 8)


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## solar_plasma (Oct 23, 2013)

Maybe this would be a point of view, both sides at least to some degree could agree with:

It is doubful, if there is a great chance for, that somebody, who is not in the condition or has the interest to learn the dynamic of the CuCl/CuCl2-process, has the experience or the attitude to use any highly exotherm sulfuric acid process with sufficient safeness and the ability to decide in which certain cases it might be the way of choice.

(said by someone who used even conc. sulfuric since the age of eleven, being glad he always has been somewhat lucky)


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## NoIdea (Oct 23, 2013)

Morning All. As usual my lack of $ means i have too improvise, for fingers i use H3SO4 [battery acid] and table salt, Every 12hrs or so i pour off the liquid and aerate for 12hrs or so, then pour back in.

Two things happen, one the CuCl/CuCl2-process from aerating occurs, and two, if you mix the damp fingers around periodically you will increase their oxidation, and, im in no hurry, been 3 days an almost finished a 200g batch.

My 2 cents worth.

Deano

P.S. my laptop keyboard is poked so i am having to use the 'On-Screen Keyboard', so be gental 8)


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## kkmonte (Oct 23, 2013)

Deano, is battery acid that much cheaper per gallon than HCl? I mean $6 for a gallon of HCl and probably about $0.50 of h202 you could start your ClCu reaction and keep reusing that for a while (assuming you keep it clean). Do the same aerating you are talking about, etc.


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## bswartzwelder (Oct 23, 2013)

Hey Deano,

Good to hear from you again. I thought battery acid was sulfuric acid H2SO4. Do you guys living on the bottom of the world have a different type of battery?

By the way, I still laugh when I think of your replies to my last remarks about the bottom half (southern hemisphere) of the world.

Bert


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## NoIdea (Oct 24, 2013)

Hi Yah, Welll, H2SO4 + NaCl <=> Na2SO4 + HCl, works ok for even upside down 8) 

DDeano


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## Tub Buster (May 28, 2014)

In October, 2013, Marcel posted a message here that a chemist friend, using the pseudonym "Godzilla", had made a tutorial for use of sulfuric acid with hydrogen peroxide. He gave the address of the tutorial:
http://goldschrott.lefora.com/topic/19399780/03-Die-SchwefelsureAP?page=-1?page=-1#.UmQjsvl7J8E 

Much comment followed. There is no evidence that any of these posters read the tutorial, which is accessible through http://translate.google.com . Certainly they did not try to repeat the simple experiment involving dilute reagents and 10 grams of plated pins.

Fraudulent imagery was posted. Photos that purported to be of a woman who had spilled acid on herself were in fact of a woman who had suffered a criminal attack. You can see how the acid was thrown in her face and flowed down her chest. This is how women are forced into prostitution in some countries. The accompanying condescending and derisive comments were inappropriate to say the least.

A video supposedly showed how sulfuric acid and peroxide cause instant combustion when spilled on a shirt. You don't get this effect when applying acid or acid/peroxide to untreated cloth. Try it. The cloth was pre-treated with an oxidant such as sodium chlorate. It is a magician's trick.

On February 2nd, 2014, GoldSilverPro posted the message below, in the "Brainstorming" thread. The part that struck me was the last line, where he says, "Someone really should play with this. Find the best mix."

In fact, I was well into my experiment when I read this, so I'll consider it to be serendipity. Beginning with the next message, I'll report my findings.



> From links somewhere on this forum, I just watched 2 videos on using weak sulfuric (H2SO4) + hydrogen peroxide (H2O2) to dissolve copper and I am sold on it as a replacement for AP. I feel it can work safely. One I saw used straight 12% H2O2 and 37% sulfuric acid (battery acid) solution (he said, because of the foam, to use a container 10 times bigger than the solution volume). The reaction was vigorous and generated a lot of heat and foam. Another video used about the same mix but diluted it considerably. It worked, but slowly. Somewhere in the middle is maybe the right answer.
> 
> This is a weak piranha solution. The "real" piranha solution uses concentrated sulfuric (97%) - 3 parts, and 1 part of, say, 30% - 35%hydrogen peroxide. It's used for such things as super-cleaning glassware. If 50%, or higher, H2O2 were used, an explosion could occur (Wikipedia) when pouring the strong H2O2 into the 97% sulfuric. However, it seems that, if you use a dilute solution, these dangers fade away. Also, once you get it mixed, the dangers seem to fade.
> 
> ...


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## Tub Buster (May 28, 2014)

OK, let's begin with risk analysis. There is a form of self-deception that says that if we don't think about a risk, it will not happen to us. It is a confusion of subjective reality with objective reality that is often seen in children. I trust that none of the forum members are subject to this delusion.

The matrix depicted below shows that risk has two components: effect or damage, and probability or likelihood. The effect of a systemic poison like cyanide is catastrophic; the effect of dilute acid, even mixed with dilute hydrogen peroxide, is marginal. That means it isn't life-threatening or immediately fatal.

The matrix allows us to compare dissimilar hazards, and on the other hand it enables us to see how a comparison of one type of hazard with another can be misleading or deceptive.

RISK CAN BE MITIGATED. Take for example the very dangerous chemical reaction that occurs when oxygen is mixed with gasoline, and it is heated. Surely no responsible person would do such a thing. Probably I should not have written about it, because some impressionable new user will read about it and immediately go out and set himself on fire.

_Cowardice is when you spend all your time inventing reasons not to do things for which there is manageable risk._

The risks of the internal combustion engine (gasoline + oxygen) have been completely mitigated, and that has made all the difference.

It is wise to remember the words of Herbert Spencer:



> The ultimate result of shielding men from the effects of folly is to fill the world with fools.


*Explosion Risk*

Definitions: 

"Piranha Solution" is a specific mix of concentrated sulfuric acid with hydrogen peroxide at a concentration of at least 35%. There is no such thing at "dilute piranha solution."

"Peroxysulfuric Acid” is formed by the mixture of sulfuric acid and hydrogen peroxide. This acid can be diluted. Therefore when people say “dilute piranha”, they actually mean “dilute peroxysulfuric”.

There are two types of explosion risk: the risk of physical damage, and societal risk.

Societal risk is where you have a loud explosion and your neighbor calls 911. The police arrive, and in the words of Ricky Ricardo, "You got a lot of splaining to do."

A lot of refiners like to maintain a low profile, due to the value of materials and the danger of the reagents used. Nothing raises your profile like an explosion, so this could be a good and sufficient reason to abandon an activity, if the probability is any higher than "unlikely". In any case, one should have a story to tell "authorities" if they inquire.

As for physical damage, there is damage due to blast overpressure, heat, shrapnel, and the effect of corrosive or flamable materials that may be thrown by the blast.

If you read safety manuals on this subject, like Department of the Army Pamphlet 385–64, "Ammunition and Explosives Safety Standards", they are full of quantity/distance tables, where for a given quantity of explosive, a minimal distance to other structures in mandated. They also have information on structures, armor and barricades that might be of some value in setting up a lab. But the q/d tables are of no use for our purposes, as we have no information regarding the explosive power of the materials we are handling. So we need to fall back on common sense. 

Assume the explosive blast, if there is one, will be no greater than a powerful firecracker, like an M-80, that is approximately the same size as the potentially explosive material. With this assumption it immediately becomes clear that the risk can be reduced by reducing the size of potentially explosive material handled at any one time.

We can also see that it is wise to avoid glass containers when possible, as they would provide shrapnel in the event of an explosion. 

Explosions of piranha solution have been reported in Chemical and Engineering News, volume 33, number 32, page 3336 and volume 38, number 59, page 1960. 

Dilute peroxysulfuric acid is not going to explode, but organic peroxides that it forms might. These are formed from solvents such as those containing ketones (e.g. acetone, methyl ethyl ketone, etc.). This risk is probably higher in the waste processing business than in the jewelry business.

Additionally hydrogen gas liberated by the digestion of metals like zinc and aluminum could cause an explosion.

*Spillage:*

If one starts with concentrated acid, it must be diluted by pouring it into a borosilicate glass (Pyrex) container containing water. Always add acid to water. This is an exothermic reaction, but if the acid is added in portions, temperature should not exceed 80 degrees Celsius. I check with an infrared thermometer. When the mixture is below 35 deg. C. it can be poured into a plastic container for temporary use. Be sure to label it.

Safety equipment includes an open bucket of water nearby, aborbent material, a large box of sodium bicarbonate or a bag of hydrated lime from the hardware store, and materials for spill containment and control—that could be as simple as a bag of kitty litter. Rubber boots, a rubber or vinyl apron or a rainsuit, gloves that can be removed easily, and something that will effectively protect your eyes are needed. The safety goggles or shield need to stay on when you are bent over, as to wipe up a spill.

The problem is the blue waste liquid containing copper sulfate. It still contains acid and peroxide. It might contain organic peroxides. If you put it in a plastic container it might react with something and heat up to a temperature that would breach the container. If you put it in glass, you have a shrapnel hazard. So either way, put the first container into a larger one for safety.

I had one spill during the experiment. I was trying to vacuum filter the copper sulfate solution, and it failed completely due to crystallization. In taking it apart, about 25 ml of the blue liquid spilled onto a counter, with a few drops hitting the floor. 

A local dollar store had been selling wash cloths at 6 for $1, so I bought some as shop rags. I dampened several and set them around the work area, so when the spill occured, it was just a matter of grabbing a cloth in my gloved hand and wiping up the spill. The first cloth was thrown into a sink, and then the process was repeated until all visible spills were gone.

What followed next was instructive. A spray bottle of ammonium hydroxide was available—normally used to clean glassware—so I sprayed it around the spill area. It not only neutralized the remaining acid, but it also "developed" the latent copper sulfate that was not visible after the first cleanup. The traces of copper became highly visible when sprayed with ammonia. 

*Fumes:*

I'll address this risk in a subsequent message.


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## Anonymous (May 29, 2014)

Thanks Tub

That was a good read, I enjoyed it.


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## Tub Buster (May 29, 2014)

The reactor I used is constructed in layers. At the center is a 2 quart (1.9 L.) wide-mouth Mason jar. This is made of borosilicate glass and has a screw top for which plastic lids are available. The lids may be used for storage, but not during the reaction. See photo #1.

*Apparatus:*
The Mason jar was put into a small Corningware dish for containment and insulation, and this assembly was then put into a large stainless steel stockpot which acts as a blast shield. The stockpot has inner dimensions 11" diameter by 9" tall. A bungee cord secures the lid. See photo #2.


The space around the jar was filled with fiberglass insulation. The pot was placed on an induction heater. With the heater set to 90 degrees, the actual temperature of the jar contents were 62 to 67 degrees Celsius, once peak temperature was attained. See photo #3.


A mantle consisting of a liner from a military parka was added to conserve heat and add a final layer of blast protection. The liner is made of synthetic materials that resist acid fumes. Due to the nature of the induction heater (it heats by magnetism), it can be placed right on top of the heater with no problems, as long as no metallic components like snaps are in contact. See photo #4.


Once the heater was operating, the stockpot produced some loud bumping noises. I examined the temperature of all components: none were close to boiling temperature. There was no condensation. I concluded that the noises were due to thermal warping of the sheet metal. After I added a shallow layer of sand to the base of the pot, under the Corningware, the noises stopped.


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## Tub Buster (May 29, 2014)

I'll mention some of the equipment used in the experiment. A section of a plastic coat hanger makes a good stirring rod (see photo #A1). The white bowl collects any acid that drips from the rod. 

Cosmetic brushes (sold at drug stores) were useful for moving dry powder. The tiny bits of gold produced by this process were a problem. They stick to brushes, float on water, and fly through the air, propelled by static electricity. I found that a spray bottle containing alcohol was invaluable for collecting and moving these small pieces. 

Incidentally, the heater is displaying 2 hours, 30 minutes on the timer, not 230 degrees.

*Accessories:*
Filtering was a problem, due to the thickness of the blue liquid. This was mostly dependent on temperature; adding more water didn't make much of a difference. Filtering through paper was impossible, even under vacuum. Filtering through fiberglass would have been an even bigger mess.

I finally decided to filter with a funnel I'd bought at a wine-making store. It has a detachable grate (see photo #A2) which let the liquid pass while catching anything larger than 2 or 3 millimeters.


This same funnel let me filter the solution through paper, after it had stood for a couple of days, and the suspended crystals had settled. 

I developed a technique of filtering the warm liquid (about 60 degrees) into a cylindrical flower vase, and then when it cooled down, pouring it into a 4 liter plastic jug for temporary storage. I let the mud at the bottom of the vase build up, and treated it like precipitated gold powder. In fact, the peroxysulfuric acid does dissolve some of the gold, but as the peroxide is used up, it drops the gold back into the mud. If you have occasion to do this type of procedure, save up all the mud and process it once.


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## Tub Buster (May 30, 2014)

*Chemicals:*

Only two chemicals are required for the process: dilute sulfuric acid, about the strength of battery acid, and hydrogen peroxide that is somewhat stronger than the 3% variety you see in food and drug stores. Here is what I paid:

The acid was concentrated; the H2O2 was 35%. The company I purchased from was a local storefront serving soap makers and other niche operations. There are many like this: check for suppliers for pottery, taxidermists and furriers, and any other industry or craft that requires chemicals. 

No HAZMAT fee, but I did purchase the pails to hold the acid jugs for transport.

*Procedure:*

Now we get to the nitty gritty. I began with about 500 grams of low grade plated pins. These were pins from connectors with varying amounts of gold plating. Some had just a bit of color on one side of the pin. Added to the mix were the metallic contents of integrated chips, transistors etc. that had been incinerated and ground in a mortar. Also added were foils from fiber chips like Pentium 4's that had been incinerated and delaminated. 

A trick with these fiber chips is, once you extract whatever foils are easily accessible, blend the remainder in a dedicated blender until the fabric turns into individual fibers. Then wash it in a gold pan. All the metallics will collect at the bottom, and the fibers will wash away.

If someone has information about transistors containing beryllium, I'd be interested in learning more in the interest of safety.

To begin with, I ran small batches, trying various concentrations. I used up to 50% sulfuric acid and up to 35% H2O2. It was not obvious at first, but after a while I began to notice that the main factor accelerating the reaction was heat, not chemical concentration. 

There are a number of disadvantages in using concentrated reagents in this process. The heat is erratic. It produces vapor, which carries acid and peroxide into the atmosphere. Undesirable side reactions are more likely. If an equivalent effect can be achieved with a reduced concentration, but an increased temperature, then using higher concentrations is a waste of reagent.

Also the copper sulfate solution becomes too concentrated, and crystallizes. The photo below shows what that looks like.

After this preliminary experimentation I decided to put all the pins together and render them all down to gold and whatever else was acid resistant. The photo below shows the pins at this point. They weighed 431 grams, plus I added another 43 g. of foils, for a total of 474 g.

The procedure I used from this point was as follows:

1.	Add the pins to the reactor.
2.	Add 400 ml. of tap water.
3.	Add 200 ml. of 32% sulfuric acid.
4.	Add 100 ml of 12% hydrogen peroxide.

The mixture warms up and the reaction rate increases. After a few minutes, add up to 200 ml of 12% H2O2. 

At all possible times, the mouth of the jar was covered by a doubled-up washcloth that was dampened with water. The reaction evolves a lot of gas and vapor, so the alternative is a condenser of some type.

At this time I put on the lid of the stockpot, covered it with the mantle, and let it cook for an hour with the heater set at 60 degrees. This produces an internal temperature of about 45 degrees.

After an hour, I added another 100 ml of 32% acid, and about 200 ml of 12% hydrogen peroxide. I set the heater to 90 degrees and let it cook for 3 hours. The internal temperature was around 65 degrees.

Then it was time to decant the flower vase into a plastic jug, and then pour the blue fluid from the reactor through the funnel and grate, into the vase. 

Then repeat from step #1 above. It took four days to render the pins.

Here are some of the gold pieces that got through the grate and were recovered later. This is a macro photo. Everything you see here weighed 80 milligrams.


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## Tub Buster (Jun 2, 2014)

*Results:*

I decided that a good endpoint for the experiment would be when there was no more visible copper, and the reaction liquid changed from blue to blue-green. This lets me save materials for another experiment in which I'll try Lou's suggestion of using warmed 70% sulfuric acid to remove remaining base metals. 

The original 474 grams of material were reduced to 96 grams, or a 5:1 reduction. Out of the 96 grams, 21.46 grams passed through a fine sieve. A medium-resolution photo of this material is at the end of the next message. 

In fact, while economically this experiment didn't make much sense, aesthetically it was quite pleasing to see the base metals melt away, leaving pure gold. Also distracting. If a pin is plated with 50 microinches of gold or less—sometimes much less—and the underlying metal is removed, what is left is the tinniest speck, and yet it glitters with all the beauty of a coin 10,000 times larger. You end up with these little specks all over the place. There's actually some advantage to that ugly black mud you get from the sulfuric deplating cell—you don't get distracted.

If someone needs a lot of little gold specks, this is a way to produce them.

*Results:*
Including the gold recovered from mud and copper cell anode slimes, I estimate I'll eventually harvest about *half a troy ounce* from the original 500 grams of pins and foils. If I had paid myself minimum wage to do the work, I'd just about break even. The cost of reagents was very reasonable: I used about a liter of sulfuric ($6) and about 2 liters of hydrogen peroxide, which was almost certainly twice as much as I should have used, so let's say $4 worth of peroxide. Chemicals used to treat waste, such as hydrated lime, are dirt cheap. It was the cost in labor that made it uneconomic.

The process is appealing in its simplicity. You want gold? Just remove the base metals and there you are. No aqua regia or chlorine and no problems precipitating. All you'd need would be some method of separating the fine gold—an Archimedes wheel, 
a miller's table, a blue bowl, etc. 

*Waste Treatment:*

Plan 'A' for dealing with the blue liquid, which contains all base metals and not just copper sulfate, is to plate out the copper in a copper cell. We'll see how that goes. The copper has some value for sale.

Plan 'B' is to crystallize the copper sulfate and store it for future use. Then the remaining copper would be cemented on iron, the iron precipitated with aluminum, and the solution neutralized, mixed with absorbent, and thrown out with the garbage.

*Claims:*

I wanted to test two specific claims made by the original poster, Mr. Godzilla of Germany. First, he points out that the process avoids nitrous and chlorine gases, and that "Only a little sulfur dioxide arises, which is carried away by the water vapor. But this is harmful in the given concentration only for the bathroom fittings." The second claim is that the process is superior to hydrochloric acid / hydrogen peroxide, because that mixture produces perchloric acid, which dissolves gold, but there is no corresponding phenomenon when sulfuric and hydrogen peroxide are mixed.

*Fumes:*

When hydrogen peroxide is added, there is considerable foaming. So what exactly is in the gas? Since it derives from hydrogen peroxide, it could be oxygen. It could be hydrogen. Godzilla suggests it is sulfur dioxide and water vapor. How about hydrogen peroxide vapor? H2O2 boils at 150 degrees, but as GoldSilverPro pointed out in the message I quoted, the bubbles carry "the solution from whence they came." This means they carry hydrogen peroxide, sulfuric acid, and peroxysulfuric acid.

I can tell you from experience that the fumes are acrid and acidic. My vote would be for sulfuric acid in those fumes. A four inch hole was eaten in the center of the first washcloth used to block fumes from the reactor (see photo). A second washcloth used for the diluted reagents is still intact, despite much use. Therefore while I think Godzilla's identification of the gas may have been incorrect, he was correct in saying that the effect of the gas is less that of nitrogen dioxide or chlorine, *when dilute reagents are used*. However it is still hazardous.


How much do you need to breathe before your lungs look like this cloth? There was no odor noticeable while the reactor was closed, but anytime it was open it was emitting gases and vapor. I'd say you need a fume hood, but you probably can do without a scrubber. Remember this acid is very destructive of human tissue, and the only margin for error you have is what you make for yourself.

Regarding *claim #2*, we know that peroxysulfuric acid dissolves gold, because that's how the sulphuric gold cell deplates things. What is the extent of the loss, and is it significant?

Due to the nature of this experiment there was a lot of visible gold mixed in with all of the sediment. We want to measure only the gold that was dissolved and then precipitated. This would require more controlled conditions, where a known quantity of gold is exposed to specific amounts of sulfuric acid and hydrogen peroxide. 

What we can say so far is that gold is lost in two ways. First, micron sized gold is produced that gets by the filtering process. Second, gold is dissolved. Much of that is quickly redeposited. We don't know how much loss is to be expected.


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## Tub Buster (Jun 2, 2014)

*Conclusions:*

I did this experiment to develop some information about the sulfuric-peroxide process for removing base metals, which could be verified and was not based on extrapolations from Wikipedia. Initially, I was interested in the way that this is a complimentary process to that of the sulfuric deplating cell. One removes base metals from gold; the other removes gold from base metals. I thought there might be some synergy in using both processes. Unfortunately, I have found no way to do that.

I did harvest some knowledge however, and I'll present it here in no special order.

*What is the risk of explosion?* I think that given two conditions, the probability of explosion can be classified as "unlikely": 


1.	The reagents must be diluted as I have described in the section on "Procedure".
2.	All materials and reagents must be free of organic solvents such as acetone.
So it depends on the vigilance of the operator. If you get sloppy, the risk goes up. I'll continue to use the stockpot if I use this process, because it is efficient and it reduces exposure. Reduce exposure, reduce risk.

*Is a fume hood necessary?* Yes.

*Can the process be scaled up?* It requires a glass reaction vessel. To process more material at a time would require a large vessel, like some of the large "kettles" that are available. As the amount of reagent increases, the effect of an explosion becomes much more serious. If you refer to the Risk Matrix diagram, you'll see that even an unlikely hazard can be an unacceptable risk if the potential effect is severe enough. To counter the increased risk you would need something similar to the very expensive Pfaudler glass-lined steel reactors.

On the other hand, there is no reason why you should not run several small reactors at once. The investment would be very modest.

*Why use it at all, when one can remove base metals with nitric acid or with warm 70% sulfuric?*

Nitric acid produces fumes that require a fume hood with a scrubber. Some of the by-products of nitric acid are explosive. It is harder to get. It is more expensive and needs to be used in a higher concentration. Nitrosamines created by the combination of nitric acid or nitrates and proteins are carcinogenic. That includes the proteins in your skin. If there is any chlorine in the system, nitric acid plus the chlorine (chloride, chlorate, etc.) dissolves gold.

Sulfuric acid (alone) as a means to remove base metals is not well documented—at least not here, in the Gold Refining Forum. To anyone who proposes using only sulfuric without peroxide I say, "Show me your data!" We need a side-by-side comparison of both processes.

Is anyone suggesting that warm (let's say, 60 degrees C.) 70% sulfuric is _not_ dangerous? I think it is quite a bit more dangerous than the dilute acid used in this experiment, and it doesn't lose its potency with time, as the peroxide mix does.

Dilute sulfuric acid-peroxide has been demonstrated to be effective in removing base metals. It is the lowest cost process for doing this, if only cost of reagents are considered (there is also cost of labor, energy, and cost of dealing with waste materials). Regarding waste, it produces copper sulfate, which is useful and has economic value. What other metals are in the waste depends upon the source of the materials.

*Why remove base metals, when I can simply deplate gold? *

You may not be working with plated material. Maybe it is brazed, maybe it is ore, maybe it is an alloy, as in jewelry. Generally, the sulfuric acid-hydrogen peroxide is unsuitable in situations where the amount of base metal is high in relation to the amount of gold—in other words, low grade material. 

It looked to me like silver was removed from the gold, but what I assume was silver was left as a light-gray silt. This needs to be determined by workers with assay equipment.


This method may be unsuitable for iterative procedures. For example, if you treat with heated acid-peroxide and then drain, you might lose 1% of your gold values to dissolution in peroxysulfuric acid. Maybe the waste solution is blue, indicating there is more copper to be eluted. So after draining you repeat the process (i.e. you do another iteration). Now you lose 1% of the remaining gold. Each time you lose 1% of what remains. 

If you retain all the drained liquid and run it through a copper plating cell, you'll eventually retrieve your gold in the anode slimes. In fact, much of it will probably precipitate as the peroxide loses potency. Perhaps a reducing agent could force precipitation.

_*An interesting application, which needs further investigation, concerns gold that is recovered by cementing on steel wool or some other base metal. Sulfuric-peroxide might be an efficient way of getting at that gold.*_

*Results:*

Below, as promised in the previous message, is a medium-resolution photo of the 21.5 g. that passed through a sieve after the pins were rendered. I stopped when the waste solution was becoming predominantly green. Not surprisingly, some of this material was attracted by a magnet.


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## necromancer (Jun 2, 2014)

lots of good tips :!: :!: 

i think i am going to subscribe to this channel.


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## solar_plasma (Jun 3, 2014)

4 days for pins seems not to be much faster than a good working AP under optimal conditions.

No doubt, safely premixed and the more diluted it is, the less aggressive it is, but also slower. 

I can see two situations, when to use sulfuric instead of CuCl2-leach: you want sulfates for whatever reason or you can get sulfuric cheaper than HCl.

Recycling the H2SO4 is more work, but you do not need to buy new acid all the time compared to CuCl2.

Medium strength (30%acid/12%) is still something for more experienced hands, - the amounts of reactants used in recovery stage are quite larger than under refining, which makes them more hazardous. I would compare it to AR, also a nasty stuff, if you make a mistake, but 50ml AR is less dangerous than 500ml.

So, in your hazard's table you need to have a look at the amounts of hazardous material, too. This alone can make the difference between "marginal" and "catastrophic" and more advanced tables of hazards take this into consideration and calculation.

You do a lot work to examine this process, which I appreciate. But having experimented with it myself I believe to read two things between the lines: 
1) you are trying to find arguments for using this process, which might cost some objectivity (is ok, just be aware of this yourself)
2) say what you want, but you have been surprised how violent this reaction actually can be


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## Tub Buster (Jun 4, 2014)

solar_plasma said:


> So, in your hazard's table you need to have a look at the amounts of hazardous material, too. This alone can make the difference between "marginal" and "catastrophic" and more advanced tables of hazards take this into consideration and calculation.


This is a good point. The waste needs to be processed quickly. Not good to store it.



> You do a lot work to examine this process, which I appreciate. But having experimented with it myself I believe to read two things between the lines:
> 1) you are trying to find arguments for using this process, which might cost some objectivity (is ok, just be aware of this yourself)


Of course. I was looking for reasons both pro and con. For example, it is obviously not useful for processing low grade material, with the possible exception of a scrap operation where everything in incinerated, and then the scale would lead to other problems.



> 2) say what you want, but you have been surprised how violent this reaction actually can be


I wasn't surprised by that. The sulfuric acid in the vapor was not unexpected, but the effect was stronger than anticipated. In general it is best to use technique that produces as little vapor as possible, unless a reflux is used.


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## solar_plasma (Jun 5, 2014)

> The waste needs to be processed quickly. Not good to store it.



Since I needed the CuSO4 as a byproduct, I just used the solution up on copper powders.


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## Tub Buster (Jun 14, 2014)

I speculated that a Blue Bowl would consolidate the fine pieces of gold from this experiment. This weekend I had the opportunity to try it out.

A blue bowl separates similar-sized particles by specific gravity. The water current carries off the lighter material first, leaving gold and other heavies behind. At least, that's how it's supposed to work. When I tried it, the first to be carried away was the gold. Oops! The gold is deplated, so it is in thin flakes, and the effect of the current is to sweep it away like a leaf dropped in a river.

So it looks like chemical refinement is the way to go. It's a bit like refining foils from computer connector fingers.


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## jungle_Dave (Jan 22, 2015)

Interesting process thanks for the education on the subject!

Jewelers in my part of the world have told me that they only use sulfuric acid for eliminating base metals from gold scrap materials they generate. 
I have a small question about how zinc reacts with this formulation if anyone knows.

If I dissolve zinc in sulfuric acid we're making (Zn + H2SO4 ) resulting in ZnSO4 + H2. 
Hydrogen is replaced by Zn and we get less H2 in our H2SO4 producing hydrogen gas + heat. Correct?

Peroxymonosulfuric acid, (H2SO5) "seems" safer in this case as water is the byproduct.
H2SO5 + Zn --> ZnSO4 + H2O
Drop the zinc and we are left with SO4 + water.

Is there a risk of the solution becoming unstable during this reaction?
I've never played with this myself but looks promising.


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## necromancer (Jan 22, 2015)

could you not filter out the gold foils directly from the blue bowl overflow hole ???

never used a blue bowl (just a thought)


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## Lou (Jan 22, 2015)

Nothing safe about peroxysulfuric acid.

The hydrogen disperses rapidly. Care needs to be taken to check the environment for sources of ignition.

Lou


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## goldsilverpro (Jan 22, 2015)

I'm locking this thread. Piranha solution is one of several very dangerous methods that will, as far as I'm concerned, be banned from discussion on this forum. Wet ashing is another one. Cyanide process discussions will be banned also, although I have been the most guilty in posting them in the past. And then there's mercury. Except for cyanide, all of those things have better alternatives. I avoid unsafe conditions like the plague (it's my first priority when designing a refinery). It's *STUPID* to use them. 

Anything else that should be banned? PM me, if so.

Alchemy, too, of course. Here again, because it's just plain *STUPID*.


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