# Recovery : Flexible Circuit with Gold circuit tracks



## Higashi (Jul 22, 2010)

Hi guys...

This is my first post here and I'm a total noob in recovering and refining PGM from electronics... 
I've read about 75% of Hoke's book....and have read thru quite a substantial portion of this forum for over a week or two now.
I don't have much problem understanding the chemical process for now (still reading and learning, not actually doing it yet).
English is also not my first language so bear with me if i'm unable to express my intentions/thoughts precisely.

my problem is about the recovery process.

a friend of mine has a lot of flexible conductors like those used in laptops and mobile phones, like almost a hundred kilogram of it, maybe more, which have the circuit track made out of gold (or at least partially).
i think it has quite a high percentage of gold because when he showed the sample to me i tried to scratched the tracks with my finger nail and it does get dented.
he asked me to do the recovering and refining as i'm his only friend that's technically inclined, as a return would split the profit with me.

i need to find a way to seperate the metal from the plastic film, at my friend's place, because :
1. my friend's place is a my hours away from me, it takes one day driving to get there.
2. my car don't have ample space to load such big boxes.
3. when it's time for refining, it will take a lot of acids to immerse just to get relatively small amount of metal apart from the plastics. i don't have big containers, or space for working with them.
4. it's hard to see if any metal left undisolved.

i need to do it preferably in a day, can't take many days leave from my job.

i considered burning them. what is the best way? 

if the plastic film dissolves in petrol (not really that cheap but it's cheap enough here that i might consider it) like PET bottles, should i dissolve and burn? or just sift thru the gel and take the metal out? got to burn the gel anyway, can't just pour it off to the drain aite?

should i fry them in vegie oil? now this is quite costly...

torch it with butane torch? i readily got one.... will use oxy or built furnace for melting. don't think the fume will be brain and lung friendly as i will have to be close to the stuffs while doing it.

what should i do?

thanks.



sample of what it look like (but not the exact item) :


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## Lino1406 (Jul 22, 2010)

Cover the circuits with 3% hydrogen peroxide,
then pour a bit concentrated HCl carefully, to watch
the reaction initiates (gentle bubbling). After some days
the gold, with part of the copper, will separate. When
activity falls, add a bit 30% hydrogen peroxide. 1 day is
not enough, and watching every several hours is 
recommended


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## goldsilverpro (Jul 22, 2010)

Before my getting into this, is it possible for you to use cyanide? If so, the gold could be quickly stripped selectively and easily dropped with zinc. No matter what you do, 1 day sounds very unrealistic.


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## nickvc (Jul 22, 2010)

goldsilverpro said:


> Before my getting into this, is it possible for you to use cyanide? If so, the gold could be quickly stripped selectively and easily dropped with zinc. No matter what you do, 1 day sounds very unrealistic.


The same thought passed through my mind but I refrained from suggesting it due to the C word that scares most people to death and I must agree with your thoughts on the time scale GSP.


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## Higashi (Jul 22, 2010)

Thanks Lino, GSP, Nick...

It doesn't have to be final separation, ie. separating gold from every metal. Just getting all the metals (circuit tracks) detached from the plastics holding it to save space and weight or else will have to rent a truck or at least a van. 

Just hearing the word Cyanide scares me,  

By burning, how will i get rid of chemicals from the plastics that might interfere with AR process? Using NaOH?
Will the heat turn the metals into oxide that will complicate the AR reactions?

Hoke and Harold mentioned about using NaOH with product of incineration process to separate metal from ashes... The word incineration makes it sound easy. However :
1. I don't understand the difference between just burning and incineration. Is it any different?
2. How can NaOH help? I understand that it disintegrates protein and convert fat to soap, but don't think it helps in this situation.

Thanks.


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## qst42know (Jul 22, 2010)

If you went the incineration route there should be nothing left but ash. However incinerating polyester is a nasty proposition. Loads of black sooty smoke and not at all environmentally friendly.


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## Higashi (Jul 22, 2010)

qst42know said:


> If you went the incineration route there should be nothing left but ash. However incinerating polyester is a nasty proposition. Loads of black sooty smoke and not at all environmentally friendly.



but what's the difference between burning and incinerating? the temperature?
I looked at wikipedia but it doesn't give any useful info.


also, i often read not to pour water into acid, but pour acid to water.
however no one seems to states why.... why?


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## qst42know (Jul 22, 2010)

I don't think this is a technical definition but I think of burning as you would burn sugar or a piece of paper, a fuel source of it's own, which may leave a carbonaceous mater behind. I would think of incineration as an assisted burning as in adding a heat source until even the carbon was consumed and nothing would remain but a grey white ash that cannot be reduced any further even with a flame and oxygen applied.

This is just my opinion on how I think of the terms.



> also, i often read not to pour water into acid, but pour acid to water.
> however no one seems to states why.... why?



Strong acids can produce heat enough to boil violently when water is added.


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## Higashi (Jul 22, 2010)

qst42know said:


> I don't think this is a technical definition but I think of burning as you would burn sugar or a piece of paper, a fuel source of it's own, which may leave a carbonaceous mater behind. I would think of incineration as an assisted burning as in adding a heat source until even the carbon was consumed and nothing would remain but a grey white ash that cannot be reduced any further even with a flame and oxygen applied.
> 
> This is just my opinion on how I think of the terms.
> 
> ...



thanks... that explains it.


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## Harold_V (Jul 23, 2010)

qst42know said:


> I don't think this is a technical definition but I think of burning as you would burn sugar or a piece of paper, a fuel source of it's own, which may leave a carbonaceous mater behind. I would think of incineration as an assisted burning as in adding a heat source until even the carbon was consumed and nothing would remain but a grey white ash that cannot be reduced any further even with a flame and oxygen applied.
> 
> This is just my opinion on how I think of the terms.


In my opinion, you covered the issue perfectly. That is exactly what my goal was when I incinerated----eliminating all traces of carbon. 



> Strong acids can produce heat enough to boil violently when water is added.



Yep---a good example is to pour concentrated sulfuric acid in to water. You get a violent reaction instantly, but by stirring, the small amount of acid is immediately diluted by the mass of water present. Reverse the process, and the amount of water that enters the acid will be converted instantly to steam, resulting in what can be described perfectly well as an explosion. 

It is safe to pour water to many of the acids you will encounter, but it's very best to never do so, so you don't form a habit that can result in an accident. Pour your acids to water, and stir well in the process, to insure your own safety. 

Do not fear cyanide. Get educated and use it within safe requirements and it can, and will be, one of the best chemicals you can use in processing gold and silver. Never lose respect for its ability to kill. 

Harold


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## geonorts (Jul 23, 2010)

Okay since the C word has been brought up i would like to bring up the M word (mercury) if Cyanide can be safely used why does everyone dislike mercury so much I have seen it safely used and every milligram recovered from correct use in Au recovery. I don't see how it could possibly be worse than cyanide and yes the C word also scares me. That brings me to my next question what will mercury amalgamate with I know Au and I assume Ag, I know it reacts with Al to form AlO, from what I have seen it won't with Cu, but what about; Sn, Zn, Fe, Pb?


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## rewalston (Jul 23, 2010)

When I was a science lab assistant (9th grade not "real life") I dropped some solder into some mercury and it all dissolved but left what I would call a scum on the surface. This was many years ago, so I can't be certain as to what the solder was composed of.

Rusty


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## Chumbawamba (Jul 23, 2010)

This topic is of interest to me because I've been accumulating a small pot of this type of Au scrap for a while--sadly, not the 100Kg that Higashi has at his disposal, but a mere 40g  However, my 40g is just the parts that have the gold contacts, as I cut away the superfluous mylar at the end of the day when I'm relaxing with my pipe.

While not a very prevalent form of scrap, and a type that takes an inordinate level of effort relative to, say, gold edge connectors to get any amount of gold, nonetheless it is there, and I figure relatively easy to process.

AP is probably a good candidate, but I would prefer to eliminate the substrate entirely by incineration and then process the ash. In that regard, a small furnace would be adequate, hot enough to completely combust the mylar material, with perhaps an afterburner or some sort of scrubber in place to eliminate harmful fumes that escape.

You can find the source material in printers, LCD displays and TVs, and basically anywhere there is a flex cable that requires a good electrical connection (like the interface between inkjet printer carthridges and the mounting head). A majority of flex cables in printers will have regular solder contacts, but nonetheless printers are the most prevalent source. You can check my database to get an idea:

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=6696

I'm curious what the yield might be for this material? I guess the only way to find out is to process a batch. I'm thinking probably 1% of the weight of trimmed mylars (at least the way I do it) is gold, so 1g of Au per 100g of trimmed mylars. JUST A GUESS. Do not use this as gospel until someone verifies


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## Higashi (Jul 23, 2010)

Chumbawamba said:


> This topic is of interest to me because I've been accumulating a small pot of this type of Au scrap for a while--sadly, not the 100Kg that Higashi has at his disposal, but a mere 40g  However, my 40g is just the parts that have the gold contacts, as I cut away the superfluous mylar at the end of the day when I'm relaxing with my pipe.
> 
> While not a very prevalent form of scrap, and a type that takes an inordinate level of effort relative to, say, gold edge connectors to get any amount of gold, nonetheless it is there, and I figure relatively easy to process.
> 
> ...



i heard it wrong from my friend... i ask him again, how much material do i have to deal with, neatly stacked it's basically almost fills 90%-95% volume of a full size container.
asked a full one week leave from job, instead of one day.

sounds crazy... absolutely crazy.

too bad i didn't keep the sample, else i could play with it, dipping in what ever could possibly dissolve the polymer base. what i could remember is that the metal conductor is quite thick compared to what i normally find in electronics. you can really feel the texture when you touch it... not really that thick but it's different.

refining can take time, recovery has to be quick, hence this thread.

would an 800 Celcius torch incinerate the stuffs?


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## dtectr (Jul 25, 2010)

Chumbawamba said:


> You can find the source material in printers, LCD displays and TVs, and basically anywhere there is a flex cable that requires a good electrical connection (like the interface between inkjet printer carthridges and the mounting head). A majority of flex cables in printers will have regular solder contacts, but nonetheless printers are the most prevalent source. You can check my database to get an idea:
> 
> 
> I'm curious what the yield might be for this material? I guess the only way to find out is to process a batch. I'm thinking probably 1% of the weight of trimmed mylars (at least the way I do it) is gold, so 1g of Au per 100g of trimmed mylars. JUST A GUESS. Do not use this as gospel until someone verifies


 
i'm VERY interested - after searching, i didn't find a definition for this "trimmed mylars" that i could understand- if you don't mind me asking - what does this mean to you & how do you accomplish it?
I ask because a recent freecycle score left me with some low grade, very dated, very wet-basement-y printers & such.
any input greatly appreciated.
thanks, all.
edited to clarify term needing clarifying ... ?


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## qst42know (Jul 25, 2010)

What are you asking exactly? 

I would guess the term "trimmed mylars" is just that, the gold plated tips cut off with scissors. Mylar is a brand name of the transparent polyester film used to make these and keyboards as well. The conductors are screen printed on and then laminated. The first photo in this thread shows these ribbon conductors with the gold plated tips.


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## dtectr (Jul 25, 2010)

qst42know said:


> What are you asking exactly?
> 
> I would guess the term "trimmed mylars" is just that, the gold plated tips cut off with scissors. Mylar is a brand name of the transparent polyester film used to make these and keyboards as well. The conductors are screen printed on and then laminated. The first photo in this thread shows these ribbon conductors with the gold plated tips.



sorry if confusing? so there's nothing really in the ribbon itself, just the exposed tips?


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## qst42know (Jul 25, 2010)

I haven't tested any so I don't know for certain. 

But I do know gold isn't used where it doesn't serve a needed purpose. If you have a quantity of these they may be worth a test to see if the designers deemed it necessary to include gold in the conductor portion alone.


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## dtectr (Jul 26, 2010)

thx qst42know. i'll just trim all i come across for now & put them in my "rainy day" box.


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## Chumbawamba (Jul 26, 2010)

dtectr,

Yes, I meant cutting the parts of the mylar cables with gold on them and discarding the rest. I would imagine the rest of the mylar has either copper or aluminum metal. As qst42know says, gold is only used where absolutely necessary, because it's expensive. You don't use it where you don't need it, otherwise everything would be gold plated because everyone loves gold


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## Higashi (Jul 26, 2010)

what do you guys think about the design of this incinerator?

http://www.youtube.com/watch?v=Vd588wRg8L0

looks like easy to build.

never incinerated before, so after watching the vid i still can't tell if it performs well enough to worth the trouble building it (and buying a blower/vacuum).

if i vary the size of the 'chimney'/exhaust, how much is it going to influence the performance? bigger the better? if i can't find big hollow tube i can use multiple small one, right?

the blower i'm thinking about buying has a maxium output of 4700 liter per minute (78 liter per second), with adjustable output. overkill? can use em for my photography works after this project.

is it a good idea to inject fuel like kerosene or gasoline/petrol (via pressure difference, like in venturi tube or paint spray gun) into the flow of 'forced' air?

how bad of an idea is it to put the air jet inlet at the top of the drum? all furnace design i've seen put the inlet at the bottom. but working with a drum, having it at the top make it less cumbersome when trying to clear the ashes.


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## Higashi (Aug 4, 2010)

nevermind... built it already, just haven't test it yet.

i use freon tank for the top chamber.

will feed fuel (LPG) using Sidearm gas burner, with forced air using leaf blower (20-70 liter/sec). 

wanting to reuse the burner for a simple furnace i'll build later using either a bucket or small drum lined with 4 inch of kawool fibre. Not sure if using only kawool fibre is less efficient than having cast molded furnace, but i built two incinerator so will be able to use two Sidearm for the furnace to make up for lack of ITC-100 and refractory bricks/cements, so to pump more BTU into it.


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