problems with Cu in HCl/bleach processing printer foils

[frank-20011]

hello everyone,

i have some dishes with platings and i have stored a few printer ribbons too.

i haven't ever work with HCl-bleach and so i decide, as a first test, to process these printer ribbons as described in these video:

https://www.youtube.com/watch?v=SJN9LW1kJWI

At first it worked fine but after a while i've niticed:

-some of the plastic ribbons which bear gold ponts surround the gold completely with plastics and so the reaction sollution can't reach the gold...i take one ribbon out, wash it with water and try to incinerate it by an open flame...the residue go back to the sollution.

after a while the sollution turn blue...green and a Au-test was negative (at the beginning of my test the stannous was positive) so it be clear to me: some cupper must be under the gold and now it get dissolved.
the auricchloride was reduced and no more traceable!

not so surprising to me but the guy in the video haven't any problems like this und he end up with a nice yellow sollution...mhm.

should i wait until my HCl- ClO- System turns into an CuCl/CuCl2-System and dissolves any copper?
there is still the "plastic-surrounding-problem"...
or should i better add a few dropps of HNO3?

is there anybody who process these ink-printer-ribbons and do he have problems like these?

best regards...frank!

 

[kernels]

Yep, the 'it worked in the video' thing is something you see quite often.

You can keep on dissolving, eventually all the copper will be in solution and then the gold will follow. This is the reason we always do what we commonly call recovery (separating the gold and base metals) before refining (dissolving and precipitating the gold).

If I had a truckload of those cartridge contacts (I assume this is what you are talking about) I would follow the AP process to separate copper and gold before refining the gold foils.

Also be aware of the yields you expect, I think someone worked out that you need about 1000 of those cartridge contact flex pcbs to get 1g of gold.

 

[frank-20011]

hello,

"Yep, the 'it worked in the video' thing is something you see quite often. "

that's true!

"separating the gold and base metals"

how would you do this?

i've made a try with AP and it doesn't work good for a lot of types of ribbons: the gold isn't good reachable for the AP-sollution, there is no reaction...it isn't as easy as it is with boards, the copper doesn't get etched...

i expect NO yields, i will only process the few ribbons i have stored and than, safe the sollution to process later my dishes and cups with it!

i've looked his video again and, after a cut, the former yellow liquid was greenisch so he has some copper there too.

thanks and regards....ahh:

one question to the "dishes process" with the HCl-bleach sollution:

often you can see they take 30% HCl and put in the bleach but i think 10 or even 5% of the HCl should be enough to destroy the NaCIO?
the pH is down enough in 5% HCl and you safe (cheap) acid and there are no more fumes as it be necessary?

is a percentag of 5 or 10 enough or should i use 31% straight from the bottle to process, mhm...lets say 10Kg of plates and dishes in 1l of these sollution?

i will not dilute the sollution more as it is necessary...

use somebody AR to dissolve the gold plating from dishes?

I've made a test with 2 drops of AR (made of HNO3 51% and HCl 30%)...at 20°C i see no dissolution of the gold but at 50°C it starts immidiately to dissolve!

or are platings on ceramic no stuff to waste time?

best regards!

 

[kernels]

With your ribbons, there will not be much copper, so just accept that you have to dissolve all the base metal into solution too if they cannot be separated by etching the copper.

Using dilute HCl will work, it is just slower than using concentrated acids. I tend to use 30% because it is cheap to buy in bulk from swimming pool supply shops. Heated AR will certainly work fast to dissolve gold from ceramic dishes, room temperature AR will be very slow. I don't even add Nitric acid to HCl until the solution containing my gold bearing material has reached 65 degrees Celcius.

Plating on ceramic is going to very thin since it is only decorative, if you have access to large amounts of free ceramics with gold then it will be worth the trouble, if you are buying the ceramics then stripping the gold, you will almost certainly lose money.

 

[Topher_osAUrus]

Using dilute HCl may not be the best idea for HCl+bleach
The bleach is basic, and the small additions will eventually push the pH from acidic to basic, preventing further dissolution.

When I use hcl and bleach, I use full strength HCl, and add about 5mL of bleach and let it work for whatever time it will. Once I see no action, or it slows to a crawl. I add another 5ml of bleach. After I add a few bleach additions, I add a little more HCl to make sure it stays on the low side of the pH scale.

AR is king, when it comes to dissolving gold though. And of course, everything works faster warm. But, with the HCl and bleach method, it being warm will push the free chlorine out of solution faster. Theres a very fine line to dance using that method.

 

[frank-20011]

hello,

shure: the bleach is basic but not so strong, with my 5% HCl i make a lot of blach additions and every time Cl come of...after let stand it for a while, the Cl-smell was gone, maybe in 1..or 2 hrs, i thought it stay longer in the sollution (o.k., it stay in s. but not in high concentration!)

the ceramic stuff is for free...shurly i don't buy such a scrap, maybe a truckload full for 10 bucks but these little test is with 10Kg and it was for free!

some beer glasses with plating too ("Radeberger")

i will use higher concentrations, in the first test it take too long.

with these ribbons it isn't easy: there are a lot of conducting paths underneath the plastic, it is like adhesive tape and so the sollution cant reach these paths but everytime there is the free etched end of such a path, elemental copper and so there couldn't be auric in sollution...under these circumstances i can wait 1 half your???

i don't know if i should take out all ribbons and incinnerate them?

"I don't even add Nitric acid to HCl until the solution containing my gold bearing material has reached 65 degrees Celcius"

why, sorry but i didn't understand this!

now, 5 hrs after i've wrote the text above, more bleach additions don't dissolve more Au like in the beginning of the test, there are some Au-foils floating in the sollution, golden on both sides with no Cu on one side...the foils are unattacked even by fresh Cl-bubbles so my conclusion is there must be enough copper (unembedded in the plastick) to react with the Cl first.

now the sollution is nice, middle-strong blue.

best regards!

p.s. i am not shure, what do you think about incineration?
without i must wait maybe for weeks until all Cu is dissolved...i am not clear what i should do now!

regards!

 

[rickbb]

If you insist on dissolving both copper and gold in the same solution at the same time you should switch from HCL/bleach to AR or poor mans AR.

But there is no reason to do that, the AP first and then HCL/bleach method works on them. I process them in the same batch as all my other plated copper parts, some do take longer. I just toss them back in again and again until they are clean plastic and the gold is released from the now dissolved copper.

 

[rickbb]

"I don't even add Nitric acid to HCl until the solution containing my gold bearing material has reached 65 degrees Celcius"

why, sorry but i didn't understand this!

He is talking about using a different process than you are using. You are using the HCL bleach process he is talking about AR, an HCL and Nitric acid process.

 

[frank-20011]

hello,

i know what Ar or even poor mens AR is and i have use it, i only misunderstood the statement but now it makes sens to me: under 65 degrees there is almost now reaction between Au and AR and so the addition of HNO3 to HCl males no sense...


waht do you think about the other questions, how do you would decide to proceed the process if you are in my situation...

regards, frank!

 

[kernels]

"I don't even add Nitric acid to HCl until the solution containing my gold bearing material has reached 65 degrees Celcius"

why, sorry but i didn't understand this!

He is talking about using a different process than you are using. You are using the HCL bleach process he is talking about AR, an HCL and Nitric acid process.

Correct, sorry about the confusion, thanks for clarifying Rickbb

 

[anachronism]

5% HCL? Get some proper HCl

 

[rickbb]

5% HCL? Get some proper HCl

I'm reading between the lines here but I think he meant to say 5% bleach. But it's hard to say.

 

[anachronism]

5% HCL? Get some proper HCl

I'm reading between the lines here but I think he meant to say 5% bleach. But it's hard to say.

You can buy 3% and 5% HCl as brick cleaner over here Rick, so you might be right or you might be wrong who knows? 8)

Jon