Gold recovery using acetic acid NaCl and oxygen/waste treatment

[Chirou]

Hello i started the gold recovering process of dissolving base metals of PCBS (copper) to free gold foils with help of NaCl + CH3COOH + O2(from aquarium bubbler)
and i also did 2nd batch with Citric acid instead of CH3COOH bc i want to turn waste product into citrate and then break it down into copper to minimalize waste in a way.
I'd Like to ask is the same process possible to recovery leftover tin from boards etc cause there's always some left on them after desoldering, and does anyone know exact temperature at which copper citrate breaks down into copper and other products cause i heard it to be around 100-120° but found no proof of this. Also i started wondering how much would it impact the reaction or rather how much would it impact the waste treatment if i would start to use homemade "purified" to around 10-15% vinegar and homemade not pure citric acid. I mean those are cheap as hell but i consider it fun to try out things so i was hoping maybe someone got any idea ^^ for example how would sugar impact the reaction, if at all cause it can be leftover in the homemade vinegar or citric acid.
Thank you very much for your time to anyone reading this ^^

 

[Martijn]

I don't think you'll get any advice here on vinegar or citric acid. Only discouragement.
Do a search on vinegar here on the forum and find out why.
Martijn.

 

[DaddyD]

I have been using vinegar highest strength I could find and salt with great success and full recovery like I said in another post I don't believe in using acid

 

[butcher]

So you use a weak acid but do not believe in using acid?

What kind of reasoning is that?

I do not understand the solution you use makes HCl in situ. or better yet stated, the hydronium ion and the chloride ions, along with the metal ions, the only difference is you use a much weaker solution with weaker ORP capabilities of the leach, along with the carbonic bonds involved with the metals involved..

 

[Shark]

Here is your "Non Acid"

https://en.wikipedia.org/wiki/Acetic_acid

 

[DaddyD]

Vinger is not really a acid but it does have properties to a certain extent I only said what works for me yes it does take longer but the results speak for itself

 

[Yggdrasil]

Vinger is not really a acid but it does have properties to a certain extent I only said what works for me yes it does take longer but the results speak for itself

That is plain wrong.
Vinegar is Acetic acid, and it too creates toxic salts when it is used to dissolve metals.
Among them Lead acetate which is so sweet it has been named as Lead sugar.

Acetic acid and Salt combined make a weak HCl.

 

[MicheleM]

@DaddyD It IS a acid
https://en.m.wikipedia.org/wiki/Acid

 

[shruli]

Vinger is not really a acid but it does have properties to a certain extent I only said what works for me yes it does take longer but the results speak for itself

I mean no disrespect when I say, you need to do some research! Vinegar, as many have already said, is an acid (acetic acid). You say you use highest strength, which concentrated vinegar is normally 20-25% acetic acid & table vinegar average 5-10% both can be easily concentrated further with heat as the acetic acid has a higher boiling point than water. If you add other house hold chemicals to vinegar without research, you could accidently create lethal gasses and not be aware of it. For example bleach & acetic acid will create chlorine gas.

 

[Shark]

I am not saying it won't work, I am just saying it is not safer. I am one of those that try different methods and have tried vinegar and salt. A good many of the reasons I don't care for it has already been described. These days I often do not have time to wait over long for a reaction to finish especially in weeks when I can do it in days. All while creating waste that is easier for me to deal with.

 

[DaddyD]

I value your opinion let's just say it works for me and leave it at that

 

[Chirou]

Oh man it turned into quite a dispute XD. In no way i myself claim that this process is in any way better but i see that it is way cheaper for gold from gold fingers and like pcb "threads" and if i'm in no hurry i mean it's cool also i know you can "concentrate" vinnegar up to above 15% or something to certain extend just by freezing it and pouring off bc after passing some concentration it freezes as well. I fully understand that later you have to dissolve gold in aqua regia anyway. The thing is i'm currently studying at university of silesia and i'm getting a lot of stuff to use for my own purpose now when i'm in bigger town so i'm trying to figure out if theres any way of using other common chemicals for like in this situation "freeing" gold by dissolving copper in one of those mixes. I also got tons of CaCO3 and different manganise oxides etc and maybe some K2CO3 soon which i'll have no use for so maybe they can be somehow utilised in lets say dropping leftover copper out of solution or something. The neat thing about this salt + vinegar/salt + citric acid seems to be that after you take your leftover solution and heat it you'll get "pure" copper from copper citrate well also there will be some sodium citrate or tin citrate but it just seems like this organic compounds might be really easier to turn into elemental form. Or maybe there are some other interesting uses for those. I wanted to try cyanide bath for some gold on the ceramics etc but this is probably distant prospect for now.

Also i'm getting electronics to recovery in so slow pace that waiting this lets say month for vinegar and salt to free the gold is no problem especially with small photovoltanic cell powering the umm aquarium pump that puts oxygen into solution. I'm actually quite jealous how abundand electronics are in US compared to where i live my friend from Alabama offered me few pallets of laptops to destroy and recover but the barier is different continent XD

 

[DaddyD]

I have a friend who recovers gold off ceramics but he crushes them and pans them

 

[orvi]

Oh man it turned into quite a dispute XD. In no way i myself claim that this process is in any way better but i see that it is way cheaper for gold from gold fingers and like pcb "threads" and if i'm in no hurry i mean it's cool also i know you can "concentrate" vinnegar up to above 15% or something to certain extend just by freezing it and pouring off bc after passing some concentration it freezes as well.

I do not know how you get that vinegar is cheaper than say hydrochloric acid. For me, it certainly isn´t. Liter of technical quality HCL (31%) purchased in 10 L canster costs about 1 euro/ liter. When you purchase only 10 L from expensive company. We currently purchase 1L for 50 cents, altough in bigger volume.
Even if you were buying posh 1L bottles of HCL from drugstore here for 2 euro/L, you are still cheaper than vinegar.
First to say, vinegar is only 8% AcOH by volume/weight (depends on brand, but it is pretty close so say that it does not make a difference). Molar weight of AcOH is 60, compared to HCL - 36. So by weight you use 1,66x more acetic acid to dissolve same ammount of metal than with HCL. And when compared in concentrations, there is 4x more acid in HCL than in vinegar by comparing weight percentages. Combined together - vinegar could physically dissolve 6,66x less metal than regular technical HCL.
Not mentioning that you create 6,66x more volume of liquid waste, which is in no means less toxic than regular HCL waste. Acetates are much more bioavailable than chlorides, and pass your skin for example much more easier.
Cheapest vinegar I could purchase here is for 39cents/liter, it does not contain only acetic acid, but many times also added colourants and other junk. So more trouble.

Overall, yes. You can do fingers in vinegar/salt mixtures, wait few weeks and then process. I do not want to do that, because it is unnecessarily lengthy and wasteful.

 

[orvi]

I have a friend who recovers gold off ceramics but he crushes them and pans them

Depends on what form is the gold on ceramic. If it is plating, then I doubt there would be some OK recovery. If these are used crucibles and pots, where gold was melted, then it could be done with ease.
Recovering foil gold with gravity separation methods is very wasteful. Gold bonding wires are different story because of their shape.