# Method for leeching using hcl+ h202



## bpc1987 (Apr 30, 2012)

I found this on the net- it proposes using hcl+h202 as a more environmentally friendly way of auto cat refining-its really interesting so check it out!

http://journals.tubitak.gov.tr/engineering/issues/muh-09-33-2/muh-33-2-1-0901-10.pdf


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## Lou (Apr 30, 2012)

The peroxide-HCl system is well known in the precious metals field and has been used for years. It is often used as an etchant. 

It works by producing chlorine in situ. Other methods involve the use of chlorate (this gives a more persistent chlorine concentration), air bubblers, or other oxidizer sources that take the HCl to H2O and Cl2.


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## bpc1987 (May 2, 2012)

Thanks for your reply Lou-sorry I should have been more clear in my previous post. when I said you should check it out because its really interesting-I didn't mean because it was a new way of leeching. I meant because leeching under different conditions have been executed and documented. Things like solution temperature, liquid to mass ratio and agitation rate have been played with and shown in tables to demonstrate the best conditions for removing almost all pgm's! 

Regards

Ben


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## lazersteve (May 2, 2012)

Ben,

The document you posted has actually been posted several times before on the forum in the past. I also posted a copy of the document on my website in the documents section several years back.

It's a good paper full of great information and details. As Lou stated, these methods have been around for a long time.

Steve


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## unitedgl (May 10, 2012)

Hello All
I have read many of the posts and pdf files regarding AP an CL scrap processing, 
But as a beginner i have some questions?
1. Fingers and pins some pins with plastic on them and some of the gold has suck to the plastic, how can I get that gold out?
2. Am i understanding the the best mix for AP is a lighter emerald green and that in the event the solution is real dark that i should add h202?
3. When i processed ceramic cups it works great but no foils....so because the gold is so small how can I remove it?, 
Was thinking about making a ele cell with SS rod and Steel wool using HCL solution to extract the find gold from the cpu"s?
4. Iam I in the right direction ....filter the foils in a coffee filter, rinse with water and melt?

Any help would be much appreciated

Thanks
BC


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## Geo (May 10, 2012)

really?


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## butcher (May 10, 2012)

unitedgl,
1. Fingers and pins some pins with plastic on them and some of the gold has suck to the plastic, how can I get that gold out?

Answer. There are several ways I will remove pins from plastic, if the plastic is brittle a hammer will break it off, sometimes even soft plastic and a hammer work, many pins have a tab and can be removed with a pin removal tool (it is a small tube that slides over the pin and also has a plunger rod to push the pin out of its socket, this is a hard question to answer when I do not know what type of pins your talking about.

2. Am I understanding the best mix for AP is a lighter emerald green and that in the event the solution is real dark that i should add h202?

Answer. Yes or you can also add air from a fish tank bubbler, if you get white copper powder you will need a little more HCl, read up on the acid peroxide document, found at Laser Steve’s web site, I believe he also has a post answering the acid peroxide questions.

3. When I processed ceramic cups it works great but no foils....so because the gold is so small how can I remove it?, 

Answer. I will usually just dissolve the gold off of the ceramic or glass using HCl and bleach, and recover gold from that solution; I also wait until I collect enough of the plated glass, so I do not waste acid covering the glass ware.



3.Was thinking about making a electrolytic cell with SS rod and Steel wool using HCL solution to extract the find gold from the CPU’s?

Answer. I think this would be bad Idea very toxic gases, and although I am not clear on the details your planning it does not sound like a good Idea, but here is a good idea, find how the people who do this all of the time do it and learn from them.

4. Am I in the right direction ....filter the foils in a coffee filter, rinse with water and melt?

Answer. You could do it that way, but the gold will not be very pure. What I would do is dissolve the foils in HCL/ bleach and refine them for a better gold product, just keep studying; you still have a lot of fun things to learn here.


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## Yggdrasil (May 19, 2016)

I see this is an old post which may be slow now, I'll try anyway

Do anyone have some numbers regarding the effectiveness of dissolving PGMs from cats?
How is the HCl/Cl method compared to straight AR for instance?

What stops the dissolving process? 
If it is the local depletion of the solution, is it possible to alleviate this by circulating the fluid sufficiently?

When using whole honeycombs, one ends up with large volumes of acids, and if finely crushed it has a tendency to clog/"solidify", due to particulate friction I guess.
But can't that be counteracted by a combination of magnetic stirring and vibrational liquefaction?
One still end up with a significant liquid holdup in the remaining particulate, but if it is flushed with sufficient acid and/or water, the remaining values should be minimal.
The liquids then can then be re-concentrated before the values are precipitated.

I hope someone can give some input to this, so I/we can learn and streamline our processes.


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## Topher_osAUrus (May 20, 2016)

Yggdrasil said:


> I see this is an old post which may be slow now, I'll try anyway
> 
> Do anyone have some numbers regarding the effectiveness of dissolving PGMs from cats?
> How is the HCl/Cl method compared to straight AR for instance?
> ...



Hello,
One of our members here: Kurtak
Has covered leeching cats in GREAT detail at this thread:
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=20573

It will answer all of your questions and many..many more.
He had a business venture processing cats using different methodologies, and elaborates on which ones and why are the best method.

Hope this leads you in the right direction.

Topher


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## Yggdrasil (May 21, 2016)

Thanks Topher.

I don't recall that post mentioning recovery comparisons between Cl/HCl and AR
It was a very interesting thread anyway so I will definitely revisit it.

I've recently been reading through Deano's extensive post.
It's a treasure trove in my eyes.

I really have quite a way to go  and targets to reach for.

PS! 
By the way, quite a few of you seasoned guys in the forum, seems to find links fast and with ease.
While I sometimes struggles for hours to find information I know I have read recently.
Do you use any special tactics? Bookmarks or such?


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## kurtak (May 21, 2016)

Yggdrasil said:


> I hope someone can give some input to this, so I/we can learn and streamline our processes.



http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=51&t=20573 (same link Topher provided)

The most important information I posted in that thread was posted in the very first post of the thread - the following quotes are from that first post in the thread 



> Leaching CATs on a large volume basis "is not" the way to process large volumes of CAT material





> The foremost thing I learned (though not the first) was that you can not leach CATs on a large volume scale - as a profit making venture by leaching them





> Now - that is not to say that you can't leach large volumes of CAT material & succeed in recovering PGMs to refine - in fact you can & will recover PGMs for refining - but that's not the real question - the real question is can you do it & make a profit & the answer to that is a big fat NO





> There are 2 main reasons you can not leach all the PGMs out of CATs - even on a small scale --- one is the solubility of the metals them selves (the Rh in particular & to some degree the Pt) & the other reason is in understanding the make up &/or construction of the CAT combs them selves



The rest of the thread went on to explain why the above quotes are true

In short there are two reasons why you can not leach CATs & come out with a profit (1) is the FACT that you "will not" get all the PGMs - period (as mentioned in the last above quote) in FACT there are some CATs that you wont even be able to leach enough of the PGMs to get what you can get selling them out right for --- the PGMs are there - you just can't leach them due to the different wash coats used by the different manufactures &/or other factors that come into play from use - such as carbon build up - or oil build up - anti freeze contamination (all the result of engine problems before the car was scrapped & the CAT pulled) etc. etc. :!: 

(2)Treating & dealing with the HUGE amount of waste created is going to suck up any & all profits you think/hope to make :!: 

The best advice I can give to "streamline your process" - is don't do it to start with --- there are FAR better ways to spend your time & money - like going fishing or on a vacation or a new car (all things that cost money but you don't get a return on)

Kurt


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## Yggdrasil (May 21, 2016)

Thanks Kurt.
A thorough and informative thread to read and learn from.

I did reread the thread and still didn't find comparisons, but it does not matter just now.
I'll leave that playground for now and try balancing down the slightly wider golden path for now :lol: 

I will revisit the cats at a later time, since I plan to extract between 10 and 20 grams of Rhodium.
The accumulation of knowledge and other PMs will be accredited on the bonus account.


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## Lou (May 21, 2016)

What Kurt said is completely true unless an initial very substantial CAPEX is made.

In fact, an aqueous leach can be done but requires some fairly serious tricks to get high 90s percent Pt/Pd recovery and 70-mid 80s Rh recovery. The acid can be used almost indefinitely, the material can be filtered and sold to the aluminum smelter, and the precious metals can be separated and recovered in commercial purity quite easily. No zinc or electrochem is required.

Setting up is a multi-million dollar affair.


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## Topher_osAUrus (May 21, 2016)

Yggdrasil said:


> PS!
> By the way, quite a few of you seasoned guys in the forum, seems to find links fast and with ease.
> While I sometimes struggles for hours to find information I know I have read recently.
> Do you use any special tactics? Bookmarks or such?



I can only.speak for myself on this...but, i use google.
Www.google.com
Then in search bar i type :
Site:www.goldrefiningforum.com kurtak cat leech

The "kurtak cat leech" is to be replaced with whatever you want to find..
Google will search *only* grf

Hope this helps


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## Yggdrasil (May 21, 2016)

Thanks Topher!
I've been using the internal search here, and there are often way too many hits to find the ones I'm looking for.
But I've lately discovered the sub forms as author and so on.
Much better after that :lol: 

Hi Lou!
Do you sell Rhodium?


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## Topher_osAUrus (May 21, 2016)

Yes, using the search on grf can seem like a daunting task.
Lazersteve has a good search engine on his site as well.

I just use google because i have it bookmarked so i just type a grf and hit it and it brings me to the spot i need (i.e. site:goldrefiningforum.com - so all i have to do it type what i want to find)
I use my phone for my studies mostly, but i am on here and google so much that as soon as i click on the search bar in chrome it brings up "view new posts, search site:goldrefiningforum.com, etc.."

I am on grf *alot*

-toph


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