separating copper from under finger foils

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  • separating copper from under finger foils

    I've tried removing the gold foils from fingers but under the gold foil is a red color which I believe is copper.
    so what now? would the copper affect the process from here, like would I still need to go through the same process as if I was removing fingers from boards?

    so if you can imagine just the foils, no board, copper stuck under the foil.
    could I just go to the next step as though i've removed the foils from the board or does that copper need to go?
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  • #2
    Process as normal.

    if you suspect tin, do not use AR made from nitric

    When you do the drop, the gold will drag down some of other metals with it.
    If the fingers were free of tin then a decent wash should do it and if a re-refine is needed, all should be good.
    In the second refining use a different dropping agent ie if you used SMB on the first, then use Copperas or Oxalic acid on the second
    If you suspect tin, do a decent boil in hcl before deciding if a second refining is needed.

    I have seen the red you mentioned and it didn't seem to affect anything for me.

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    • #3
      The finger foils are definately copper based, pins i've removed from cpu's have tin solder so yeah, looks like two different processes.

      I'm putting up a video about removing fingers in a couple hours so i'll post it up so you can see what i'm talking about.

      Today I had a guy drop some boards off on his way to town to sell his gold and silver blobs to a bullion dealer.
      Must say I was very impressed, he had huge blobs of gold and 4 massive blobs of silver which he got from fuses & switches, quite stunning really and I was in envy.
      I wouldn't of sold them blobs though, they looks fantastic.

      I'll post up my new video as soon as it loads.
      Buying eWaste link here

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      • #4
        Here's my new thing, using a soldering iron to remove fingers from boards and pins from cpu's.
         
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        • #5
          That is excellent information. Ben, one thing I liked about your video is that you mentioned, several times, contamination. From my own experience in working with chemical gold recovery, contamination is one of the greatest problems. Copper doesn't worry me so much, but the tin solder does. It can almost stuff a complete process to a point where you have to then use other procedures to clean up the mess you have left. If we could somehow recover all that tin, we would do well. Price of tin, I believe, is quite good. But I'm not quite sure. Like you also mentioned, the more chemical you use, the bigger the cost, and the lower the return.

          I'll certainly have a closer look at your idea with the soldering iron. I've got several of the cheap ones you mention, just need to clean and shape up the tips. Heat guns are good and have their place, but you are quite right about the amount of power you use. My last power bill was ugly, but there you go.

          Only other query I have is with the CPU's. How much of the pins would be left in the base once you remove them with the soldering iron? I know that on boards where you have pins that are completely gold platted, you can leave quite a bit behind if you cut them off say with an air chisel or even side-cutters. Problem is that if you recover the whole pin you get a lot of solder left on them.

          Anyway, good work Ben.
          OKEDEN SCRAP & PM's
          http://www.okedenscrapandpms.com.au

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          • #6
            The pins from fibre cpu's come off completely as we're not cutting throgh the pins, just melting the solder enough to have them fall off.

            I have come to realise that gold foils from fingers don't need any chemicals or refining at all.
            infact it's a total waste of time because gold foils don't have anything but gold & copper.

            So all we have to do is melt the foils into a blob which in the process will eliminate some of the copper too.
            What we would have is something around 14kt, a guy dropped by the other day showing me exactly that, 14kt gold blobs that he was selling to a bullion dealer.
            he said that if he used chemicals to refine that 14k into 24k it wouldn't make any difference in the value, except wasting time & money on chem's.

            50g of 14k x $34g = $1700
            30g of 24k x $58g = $1740

            but I don't even think 50g of 14k could turn into as much as 30g of 24k
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            • #7
              Cheers Ben, interesting stuff. I agree that I doubt 50g of 14k would turn into 30g of 24k. I would imagine that the gold platting is a lot thinner than the copper. In fact when stripping gold from fingers using HCL and Peroxide, the gold will float because it is so thin. I reckon you'd be lucky to get 15g of 24k gold, 20g at outside.

              However, the cpu's are interesting. That would be a great way to recover the GP without using chemicals. Okay, me being me, I would then still refine. Firstly in a sulphuric cell and the AR, but that's just me. Maybe the soldering iron might have other applications, such as pins on some boards. Anyway, thanks for the info. Always looking for better ways.
              OKEDEN SCRAP & PM's
              http://www.okedenscrapandpms.com.au

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              • #8
                The foils are actually three layers of metal. From the bottom you have copper. The copper is applied to the board by a process that is the same as silk screen printing. A copper paste is applied and then it is passed through a large machine that is much like a microwave oven. It heats the copper paste and sets it as a copper sheet. Then it goes through a plating solution that applies a layer of nickel. The nickel layer is used as a barrier to stop the gold from migrating to the copper and vice-versa. Pure gold metal and pure copper metal placed in close proximity to each other will slowly swap atoms until you have an alloy of copper and gold in each spot. Of course it would take a very long time but it has been proven that the two metals migrate to one another across empty space between them. After the nickel barrier has been plated, then the gold is plated on the parts. The foils removed in this way is still only about a quarter gold or about 6K if direct melted.

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