# Cementing gold with copper



## Valladolid (Mar 15, 2018)

Hello everyone, my name is Angel, this is my very first post and i hope i am doing it right.

I need your help, i am a cell phone and computer tech and i get lots of cell phones and computer parts into my hands every single day i have to sort cables and gold plated connections, some of them look very solid and thik for for gold content, i used to throw everything to the recycling garbage but always bothered me knowing that small amount of gold will ad up in time so i decided to scrap it and save the gols pins and cables.
Over two years it accumulated a lot so i decided read about gold recovering, i noticed most people got it wrong on the presipitation so i decided to try with small amount and this are the steps i followed:
Clean, and depopulate connectios, most of them are small gold fingers, i added pure water then add small amounts of nitric acid and let it react, then i decanted the acid and added more water and acid and left it for few hours, it looked like lots of gold flakes floating arround, probably half of a gram then i decanted the acid again and without adding more nitric acid i added more water just enough to cover it, i then added hydrochloric acid in small portions untill i see no reaction, i let it over night, next day i checked all the gold have disolved so i proceed to precipitate with SMB, nothing heppened i left it for two days but nothing will happen, i asked a jewler and he told me to add copper until it stops reacting, i did add copper but nothing precipitates, i only see white cloudy stuff floating arrown, i followed direcctions very carefully something along the way i did wrong
Please help


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## jimdoc (Mar 15, 2018)

Please don't double post.


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## kernels (Mar 15, 2018)

Valladolid, 

Your basic idea was correct, you tried to remove all the base metals before dissolving and precipitating the Gold, your problems probably lie in the details.

For starters, Gold plated connectors from modern PCs are usually a very thin plating, you have not specified how many kilograms of pins you started with, but it is possible that there was just hardly any Gold to start with.

After you dissolved all the base metals with HNO3, did you filter off the Gold foils ? Was there only Gold foils and no other parts of the pins remaining ? Got a picture ?

There was no need to add water before adding HCl, and also no need to add HCl in small quantities, a massive excess of HCl is not really a problem. What you need to avoid is a massive excess of HNO3 (but that is not as crucial when you cement on Copper)

OK, so it sounds like you managed to dissolve the foils OK, did you filter this 'pregnant' solution and wait for all fines to settle completely before trying the precipitation ? You really need some Stannous Chloride to test solutions as you go, that way you would know where the Gold is at all points.

Adding Copper to a solution is good advice, as long as it is acidic, which yours should be, the Gold will cement out on Copper. What form was the Copper in that you added ? I hope it was a pipe or bar or something solid ?

Finally, this is not a half-arse type hobby, if you don't understand what is happening and what is supposed to happen, you are just creating poison for no reason.

On that note, I hope you have stored all the Copper Nitrate solution you created, it is extremely poisonous and probably a federal crime to pour it down the drain.


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## Valladolid (Mar 15, 2018)

thanks a lot for your reply Kernels

I did filtered the solution and put the paper filter inside the flask to recover any gold, the connectors are really thin since most of them are from cell phones, ipads and tablets, it was a small amount, about 400 grams, every connector comes from flex cables so i cut the fingers off the flex cable but still a small piece of copper and cable was left, and after the reaction lots of flakes were floating around, the copper that i used was from power supply, i peeled the coper from plastic to add it to the acid, there was not other contamination or anything other than the left over of the PCV that hold the fingers, i used the wires from power supply to do two things at once, cement the gold and get pure copper. now i do not know how to precipitate the copper, and the gold, i have been following all the precautions and avoid throwing away any acid, since this is my first time i have to recover the copper and neutralize the acid in a proper way.

I have thrown away lots, i mean lots of electronics before i realised its value so i decided to scrap and save it in my free time but now i am kind of overwhelmed with so many boxes, pending to be scraped and many little containers of different kind of gold plated pins, flex cable connectors, striped mother boards, microchips, monolithic capacitors and aluminium so i really need to learn this process.


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## Shark (Mar 15, 2018)

I can understand being overwhelmed by the mass of materials. As an option, you could sell some or even all of it and buy gold or silver, or whatever you decide to use it for. You could let someone refine all or part of it and get some of the gold or silver back as in a toll refine while reducing your volume on hand. There are several options to reduce some of the stress from being overwhelmed that will allow you to get some relief while continuing to learn. Learning to refine ewaste is quite a chore in itself. It can also be very enjoyable as well as rewarding.


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## kernels (Mar 15, 2018)

Valladolid said:


> i used the wires from power supply to do two things at once, cement the gold and get pure copper. now i do not know how to precipitate the copper, and the gold,



OK, so just so I can clearly understand, I think you stripped some copper wire and used the copper wire to try and cement Gold from solution. 

The problem with that is that Gold will cement all through the woven part of the copper wire as well as on the outsides, but I suspect from a few hundred grams there might not have been much Gold to start with anyway. Often what looks like a lot of foils is actually not much pure Gold.

I would have recommended cementing onto some chunky copper bar or a piece of cut and flattened copper pipe. What you would expect to see is a very fine brown powder magically forming on the Copper when the solution is stirred with the Copper. 

One of the big problems is that you have started with something that probably didn't have much Gold, and you really need some experience before you start working with less than 1g at a time. 

If you are serious about wanting to learn this trade, your best bet is to start with at least 500g of close cut fingers from Ram, that will give you around 2g of Gold which is a nice amount to work with.

Now, what to do with what you currently have . . . 

It will be near impossible for us to tell you where the Gold is now, there is a chance that your original SMB precipitation did work, but the Gold was so fine that it settled to the bottom and wasn't obvious.

Copper pretty much always works, so if the Gold was in solution you would have seen something on the Copper.

If you make some Stannous Chloride, you can test your current solution to see if it holds any Gold.


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