# Question concerning the History of the AP process,..



## Anonymous (Jan 8, 2008)

Hello All,

I have been reading Hoke and lurking the forum, learning so much!
Many thanks to everyone!  
Does anyone know the history of the Acid-Peroxide process, when it was invented and by whom?
Hoke doesn't mention it,...anyone know?

Thanks so much,
FB


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## Harold_V (Jan 8, 2008)

Hoke doesn't mention it because, in her day, just as in my day, nitric acid was readily available, so there was no need. 

Steve may well be the one that can answer your question about who "invented" the idea, but it's just fundamental chemistry for those that understand it well. 

Harold


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## lazersteve (Jan 8, 2008)

Freaky,

My experience with using the AP process came about from a personal quest to find a suitable replacement for dissolving base metals without the need for nitric acid. I did not 'invent' the process more as Harold points out, it was a matter of Chemistry for me.

Since my discovery of the usefulness of the AP process I guess I can claim that I have contributed to the popularization of the process here on the forum. 

Some time after I had experimentally determined the correct ratios for the mix I happened across documents which supported my find. I have also run upon mention of similar processes in several literary works printed prior to my work. Come to find out the AP process is actually claimed to be used at some large scale refineries.

As with any chemical process, they have all been around since chemicals came into existence, it's just a matter of who stumbles across them and formulates an application for a given reaction and then utilizes what they have discovered.

I'm 100% sure there are many 'undiscovered' processes of base and precious metal dissolutions. Most guys and girls just don't have the creative drive or chemical background to calculate and test their calculations with real life experiments to find these processes. It's much easier for most folks to wait around for someone else to do the ground work for them.

Steve


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## goldsilverpro (Jan 9, 2008)

Although the basics have been known, I think Steve deserves about 95% of the credit for advancing both the AP and AC processes to a point that no one else in history has.



> Come to find out the AP process is actually claimed to be used at some large scale refineries



Steve, do you have more data on this - or, your original source for your statement? Seems iffy, to me, but there could have been some isolated usage, I guess. Have you yet thought of an economical, efficient, fast way to use either of them on a grand scale? You could very well be on that threshold.


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## Irons (Jan 9, 2008)

I've been trying out a hybrid process that starts as AP, then Hypochlorite is added to use up the HCl, generating Chlorine and also begins raising the Ph of the solution. The finished liquor is mildly acidic with HCl.


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## Noxx (Jan 9, 2008)

And it work ?

The thing is, it seems to used a lot of chemicals...

But it's interesting...


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## Irons (Jan 9, 2008)

Noxx said:


> And it work ?
> 
> The thing is, it seems to used a lot of chemicals...
> 
> But it's interesting...



AP works best when the HCl is concentrated, but as the HCl is used up and diluted by additions of Peroxide, the reaction rate slows down. Adding Hypochlorite generates chlorine which is more agressive than AP and only uses up the residual HCl that's already in solution.

HCl/Cl works best in dilute solution because of the limited ability of water to absorb Chlorine. I found that using con HCl with Hypochlorite tends to react vigorously, especially when warm and much of the Chlorine is lost. This is ok if all you want to do is generate Chlorine to precipitate Palladium, but for digestion, it works better cool and dilute.

It's a work in progress. I can't see where it would cause any problems.


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## Lou (Jan 9, 2008)

Acid with strong enough peroxide will liberate chlorine itself. That is why to a certain extent, bleach with acid is relatively similar, as it also liberates chlorine since hypochlorite is unstable in acidic conditions.


HCl-peroxide has long been known as an effective method for dissolutions and etching, particularly with the refractory metals.


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## Irons (Jan 9, 2008)

You're right about the similarity of the process. I think the HCl/Cl via Hypochlorite is a bit cheaper than using peroxide.

I'm just trying to use everything but the squeal. There's nothing wrong with Acid/Peroxide.

A penny saved is a penny earned.


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## lazersteve (Jan 9, 2008)

GSP said:


> Steve, do you have more data on this - or, your original source for your statement? Seems iffy, to me, but there could have been some isolated usage, I guess. Have you yet thought of an economical, efficient, fast way to use either of them on a grand scale? You could very well be on that threshold.



Chris, 

I was using AP and HCl-Cl long before I realized it was used in bigger refineries as I have mentioned.

Here's the reference for my statement:



Small Scale Refining of Jewelers Wastes by Roland Loewen pg.175-176 C1995 said:


> Hydrogen Peroxide and hydrochloric acid will dissolve gold. This is used in several refineries. One refiner reported that the recovery of PGMs was much improved when hydrogen peroxide rather than nitric acid was the oxidizer. The known affinity of platinum and palladium for nitrogen compounds make this a believable conclusion. Unless extended boiling of solutions to remove nitrogen compounds is done it is quite possible that some forms of nitrogen could combine and hold PGMs.
> 
> We have no experience with hydrogen peroxide oxidation. The use of the 50% grade is reported. We speculate that the metal is in hydrochloric acid solution and is treated by adding the H2O2. Because hydrogen peroxide is an unstable material considerable care in its use is needed. The stream of peroxide should not be introduced under the solution because of the chance of draw back to the supply tank. There the metals present will likely catalyze peroxide decomposition which can be explosive.
> 
> ...



I have also found this same formula in several texts.

What is odd to me about his mention of the use of peroxide is his lack of references cited on the source of the material. He has references throughout the book (just about every paragraph) on many subjects, but not this one. Just above this section he mentions HCl and Chlorine gas without reference also.

I experimentally stumbled across the use of AP for stripping base metals around three years ago. I've owned this book for less than a year. I used AP to dissolve my first batch of monolithic capacitors around two years ago. The 3% stuff is super slow, but it works very well on Palaldium. I reallly dislike evaporating nitric acid based PGM solutions. With AP this problem is solved.

As for up scaling the reaction, yes. I have penciled out a contraption to use AP in a continuous configuration which works with circulating pumps, filters, and electrolytic reactions. Theoretically you can electrolytically rejuvenate the AP as it's saturated and recover the copper moss, returning the rejuvenated solution to the reaction vessel. In essence you can dissolve pounds of copper based pins in a very short time and retrieve the gold foils when the copper is gone. The copper ends up in a separate bucket in mossy form.

I built a prototype and turned it on, but the spent AP I used was too saturated when I first started the device  . Huge amounts of chlorine gas were evolved in just a few seconds of operation. Ideally you would start with a fresh solution and turn on the electrolytic cell to maintain the proper CuCl2 concentration to affect rapid dissolution while plating out the dissolved copper.


Steve


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## Irons (Jan 9, 2008)

That might be useful for a Chlorine Generator.

If someone hands you lemons, make lemonade.


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## Lino1406 (Jan 11, 2008)

How about using Ammonium Peroxide + Sulphuric + H2O2?


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## Irons (Jan 11, 2008)

Lino1406 said:


> How about using Ammonium Peroxide + Sulphuric + H2O2?



http://en.wikipedia.org/wiki/Sodium_aurothiosulfate

Ammonium aurothiosulphate?


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## Lino1406 (Jan 11, 2008)

Sorry,
I meant Ammonium (or Sodium-) Persulphate + H2SO4 + H2O2


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## Lou (Jan 11, 2008)

I use that in the lab for cleaning. Ammonium persulfate and concentrated sulfuric acid form something like a milder version of Caro's acid/peroxymonosulfuric acid.


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## Shaul (Jan 12, 2008)

Check out this free pdf download: 'Applications of Hydrogen Peroxide and Derivatives' which I came across yesterday in my travels. It just may answer everyone's questions....or not.

http://tinyurl.com/2fdw5w

Shaul


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## Lino1406 (Jan 12, 2008)

Hello Lou,
I can think of Perulphate + Sulphuric + H2O2
as a cleaner of course, but what I meant is a 
replacement for the other AP process
with (possibly) the following advantages:
1)Less gold dissolution with the absence of Cl- ion
2)Should work on nickel too
3)No smell of chlorine
3)In comparison to another "bathroom process" -
FeCl3/H2O2, quicker and not giving the
nasty Fe sludge


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## Irons (Jan 12, 2008)

Lino1406 said:


> Hello Lou,
> I can think of Perulphate + Sulphuric + H2O2
> as a cleaner of course, but what I meant is a
> replacement for the other AP process
> ...



I've been using H2SO4/H2O2 for a while and I prefer it for stripping base metals because it doesn't fume and the H2O2 can be rejuvinated through electrolysis. In th old days, H2O2 was manufactured by the electrolysis of dilute H2SO4.
It's very agressive, I've even made Rhodium Sulfate with it (from the hydroxide).


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## Lino1406 (Jan 12, 2008)

Hello Irons,
1.Try to add persulphate too
2.Remind how you get the hydroxide
Lino1406


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## eagle2 (Jan 20, 2008)

I have tried Irons suggestion of washing my Gold precip with dilute sulfuric acid, several times, instead of HCl. 

It works very well in removing the last traces of tin and copper salts, but most of all I`ve noticed it also reduces the electro-static repulsion of the 
Gold particles of the precip, so that the precip becomes more cohesive and collects easily in a corner of the beaker.

It then is very easy to move it where you want, with a wash bottle.

Al


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## Anonymous (Jan 20, 2008)

I would delete the tiny link in the first post of this thread, it does not lead
were most would want to go.

Jim


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## Harold_V (Jan 20, 2008)

While the link below the one in question shows what is apparently porn, I clicked on the one intended and found it does, indeed, talk about 'Applications of Hydrogen Peroxide and Derivatives'. I'm on a painfully slow dialup, so I didn't try to download the sizeable file (about 12 mb). If you have a high speed connection and are willing to review it, please do so and let us know if it pertains to refining, or not. I hesitate to delete the link if it could serve a useful purpose, but will do so if it does not. 

Thanks,

Harold


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## Shaul (Jan 20, 2008)

Harold;

I fail to understand why you would want to delete the link I posted to the book about Hydrogen Peroxide. 

The original question was about the history of the AP process with the discussion evolving into other matters connected with Hydrogen Peroxide.

I posted the link because I felt that this book might answer some of those questions.

Published by The Royal Society of Chemistry and with 286 pages, it covers the history as well as the total (in-depth) chemistry and applications. It's a lot more than just using it for cuts and bruises.

Granted that perhaps it should now be moved to the 'Books & Other Info.' section, but to delete it??

I've seen plenty of things posted to the forum that have absolutely nothing to do with Refining. If you want to start deleting, I should think you'd have your work cut out for you.

Shaul


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## Anonymous (Jan 20, 2008)

That was my fault, I clicked on the link in the message and it directed me
to material that is not only not refining but maybe at first porn, sorry when that popped up, I did not sick arround to wait on anything else.

I do no want to cause anyone any heart burn, I just thaught the site may have changed and the link may have been dead or something which cause
the wrong info to be displayed.

Jim


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## Harold_V (Jan 20, 2008)

Shaul said:


> Harold;
> 
> I fail to understand why you would want to delete the link I posted to the book about Hydrogen Peroxide.
> {snip of extended comments.}



Pleaser read my comments once again. You have them completely wrong.  
Did you not read this part?



> I hesitate to delete the link if it could serve a useful purpose, but will do so if it does not.



Harold


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## Shaul (Jan 20, 2008)

Harold;

I both read and understood what you wrote. What I don't understand is why you didn't ask me first.

I would think that if there is a question or conflict with a certain piece of information, then basic courtesy would be to first ask the member who posted it, for clarification.

Instead, you asked someone who was not involved to "review it and let us know if it pertains to refining, or not".

The point of contention here is not whether the book serves "a useful purpose" but rather "if it pertains to refining, or not".

For this reason I wrote that I have seen many items posted to the forum which have absolutely nothing to do with refining, but yet are still there.

Shaul


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## aflacglobal (Jan 20, 2008)

Shaul, I don't believe Harold was directing anything at you. He has slow dial-up so he was just asking that if anyone reviewed it and found that it was something different than what it said it was to let him know and he would edit the link. We have had previous problems with porno bombers in the past and tend to watch out for them. I don't believe he was trying to be mean, That's just Harold. :lol: :lol: :lol:


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## Shaul (Jan 21, 2008)

Hi Ralph;

I never felt that Harold was trying to be mean. It was obviously just a simple misunderstanding, common when trying to translate between english.

Also, I clicked on the link and it came up as the download site, if anyone ended up on a porno site, it surely didn't come from me.

Shaul


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## Harold_V (Jan 21, 2008)

Shaul said:


> Harold;
> 
> I both read and understood what you wrote. What I don't understand is why you didn't ask me first.


Understand that this is nothing personal. 

I have a job to do here---to insure that the board runs smoothly, and stays somewhat on topic. I have read your posts and found them to be informed and useful. I also clicked on the link in question and was directed to a page which, along with a link that allows for a lengthy download of the article you suggested, clearly showed another link to what appeared to be porn. I asked someone, anyone, to explore the proper link and report if it was anything but what had been represented. I was under no obligation to ask of you what it said, nor would it have been a good idea. I don't know what your motives are, although they appear to be sweet and pure, nothing beyond gold refining. I wanted a third opinion, for obvious reasons. A reader was alarmed at what he found by following your link. For all I know, that was intentional. It wouldn't be the first time I've seen readers use their sig lines or other means to lead to porn sites. 



> I would think that if there is a question or conflict with a certain piece of information, then basic courtesy would be to first ask the member who posted it, for clarification.


That gets down to asking the fox to watch the hen house, assuming you are not what you represent yourself to be. By asking for a reader to comment (not you) I'd expect to get the proper answer. 

Yeah, I know, it's like I'm accusing you of some kind of ill deed. Looks like that, but it's not intended that way. If your feelings are hurt, I'm sorry for that, but I have a job to do and I do it the best way I know----which is often to get a third opinion (the reader that would report back if anything was amiss).

Get over it, Shaul. If you can't get over it, then change the link you provided, replacing it with one that takes the readers directly to the download, instead of the page that gives a link to the download. Had you done that in the first place, we wouldn't be having this conversation. 



> The point of contention here is not whether the book serves "a useful purpose" but rather "if it pertains to refining, or not".


My response is this matter is closed. You are making something of nothing. I have no intentions of getting caught up with you and your play with words and meanings. I made it perfectly clear that if it was useful it would remain. Please drop the subject and get on with life. 

Harold


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## Shaul (Jan 21, 2008)

Harold;

My only desire was to provide a link to a book which I felt might be beneficial to others and if anyone ended up at a 'porn' site, I am truly sorry; that was never my intention.

I very much appreciate your expertise, openness and honesty, besides the hard work you put in, in service of the forum.

If I offended you in any way, you have my sincere apology.

Case Closed.

Shaul


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## Harold_V (Jan 21, 2008)

Thanks, Shaul, for your understanding and your glowing comments. 

I think it's clear that there is a lot of good that comes from this forum----we all have our best interest in its survival, and we obviously depend on folks like you that can provide much needed information. I try to look upon each and every reader as family! :wink: 

Your link is very welcome, as are you!

Harold


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## Shaul (Jan 21, 2008)

Thank You. Much appreciated.

Shaul


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## Palladium (May 5, 2008)




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## eagle2 (May 6, 2008)

Palladium. thanks so much for the link. I have been wanting Hoke`s info as a reference/ comparison to my other authors.

Al


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## Palladium (May 6, 2008)

Your welcome 
Thank gustavus :wink:


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## Palladium (Nov 25, 2008)

Great thread to learn from. Go back to page 1.


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## jsargent (Dec 14, 2008)

lazersteve said:


> GSP said:
> 
> 
> > Steve, do you have more data on this - or, your original source for your statement? Seems iffy, to me, but there could have been some isolated usage, I guess. Have you yet thought of an economical, efficient, fast way to use either of them on a grand scale? You could very well be on that threshold.
> ...



I'm a little confused on the use of AP. The idea is to dissolve the base metals, leaving behind the relatively insoluble gold, right? My question is how much gold will be lost because it too has some limited solublity in AP, if I read correctly?


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## lazersteve (Dec 14, 2008)

jsargent,

The short answer is that AP will dissolve gold very slowly. 

The rest of the answer is that the amount of gold dissolved can be limited to a very small amount if the peroxide levels are kept to a minimum.

The true reactive ingredient in the 'AP ' reaction when use for removing base metals is Copper II Chloride. The acid and peroxide are only used to create the copper chloride needed to keep the reaction going.

When you are actually trying to dissolve gold it's best to use AR or HCl-Cl if the gold is in a finely divided state.

Any gold dissolved by the initial reaction with AP while the CuCl2 is still forming will be self precipitated as a fine black powder as the copper levels in the solution increase.

Steve


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## jsargent (Dec 14, 2008)

lazersteve said:


> jsargent,
> 
> The short answer is that AP will dissolve gold very slowly.
> 
> ...


 Outstanding answer Steve! Clear and to the point and that's why I have found this forum to be invaluable. Many Thanks


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## Nopyrite (Jan 18, 2010)

lazersteve said:


> jsargent,
> 
> The short answer is that AP will dissolve gold very slowly.
> 
> ...


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## eagle2 (Jan 19, 2010)

Nopyrite
Looks like your Gold went into solution. 
The way I recover small amounts of Gold mixed in with large amounts of base metals is with a Zinc precip.

First the solution needs to be brought as close as you can to neutral Ph, without precipitating a lot of base metals. Heat the solution to about 50-80c. Add about 1-2 grams of dissolved and filtered Sodium or Ammonium Thiosulfate per liter.
Then add small amounts of Zinc powder with stirring. Keep stirring 5-10 minutes. Add just enough Zinc to precip the antisipated amount of Gold in solution.

This will give you close to 100% recovery.

Al


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## Harold_V (Jan 19, 2010)

In a case where one decides to recover values with zinc, you should consider the idea of leaving the solution acidic, perhaps down around 2 pH. Introduce a tiny amount of zinc, which will reduce some of the base metals, which, in turn, will precipitate the values. By using precious little zinc, you should be able to achieve a 100% recovery of values by this method, without including the base metals. They go back into solution when the values are precipitated. I get the idea that's what's going on with your method. Could be wrong, however. 

Flirting with pH can be troublesome in that when you lean towards basic, pretty much anything that's in solution has the tendency to precipitate. Have you had any experiences that are in keeping with that thought?

Harold


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## eagle2 (Jan 19, 2010)

Hi Harold
Yes that depends on the base metals in solution and very importantly, their concentration. Tin starts to precip around Ph 3. Iron soon after. You absolutely don`t want to precip the base compounds here. But if the solution is too acidic the Zinc will dissolve without doing any work of reduction.

AP processes are way acid, well below Ph. 0.1 i`m sure. Its necessary not to be that acid for a Zinc precip. 

I gradually raise the Ph, until the soultion starts to get cloudy, then back off some with HCl. Adding Zinc always has the effect of raising the Ph. anyway. So the precip of Gold is well contaminated with base metals. But at least you have recovered most all the Gold from a very large amount of base metals.

It used to be the recommened method of using Zinc, was to add 5-10 fold excess Zinc, with much stirring, hoping to cement the Gold on the Zinc particles.The Gold covered the Zinc particle and most of the Zinc was unused and wasted. Then they only claimed about 70% recovery!!

The important discovery that made Zinc so much more useful was the addition of the Thiosulfate. This chemical has an effect which uses all of the Zinc particle and allows close to 100% precip. 

I dont have the document that describes this effect, handy with a link, but if anyone requests it, I will find it. 

I have used this method many times and it works.

Al


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