AP Recovery Gone Wrong

[JacobsMetals]

I recently stripped an old Hitachi plasma tv (lots of pins and fingers but thinner plating) and tried using AP (HCL+H2O2) solution at a 2-1 ratio to remove the gold fingers and tossed in 90% of the pins figuring it would break down the copper at the cut end and work it's way through and leave the silver based pins alone to try converting to silver chloride at the next step. So issue is everything appeared to be functioning correctly till 6 or so hours later when I checked up on it and the gold was mostly dissolved and the pins blackened. Solution is still an emerald green and there is a black powder at the bottom of the container but I'm not sure what it is. My thought was it might've went after the gold since it was so thin and dropped the gold out of solution after it started working on the copper more but I'd like to see what the community thinks and if y'all have any solutions/tips at this stage? I have to gather some tin before I can test the solution but I'm still planning on filtering it tomorrow and at least get the remaining plastic out and setting the powder to the side to dry out.

 

[acpeacemaker]

I recently stripped an old Hitachi plasma tv (lots of pins and fingers but thinner plating) and tried using AP (HCL+H2O2) solution at a 2-1 ratio to remove the gold fingers and tossed in 90% of the pins figuring it would break down the copper at the cut end and work it's way through and leave the silver based pins alone to try converting to silver chloride at the next step. So issue is everything appeared to be functioning correctly till 6 or so hours later when I checked up on it and the gold was mostly dissolved and the pins blackened. Solution is still an emerald green and there is a black powder at the bottom of the container but I'm not sure what it is. My thought was it might've went after the gold since it was so thin and dropped the gold out of solution after it started working on the copper more but I'd like to see what the community thinks and if y'all have any solutions/tips at this stage? I have to gather some tin before I can test the solution but I'm still planning on filtering it tomorrow and at least get the remaining plastic out and setting the powder to the side to dry out.

Hey,

A 2:1 ratio is way too much. I used to do 3:1 when I did large barrels, but there are people here, that will tell you that's even way too much. It really only takes a small amount of h202 to get the reaction going. An air bubbler really helps.

You said your ratio of acid, but curios how big of a container you are using with volume of liquid. With pieces from one Hitachi tv there won't be much gold. It sounds like flashplated. You have so much oxidizer added the flashplate dissolved and then cemented back out of solution on the very same pins. Which is why they're black. It is good to have stannous, but I have a strong bet you won't have any gold in solution. No guarantee though.

Last question is why do you think the silver colored pins are silver? That's not me trying to be smart either lol, its a legit question.

Andrew

 

[JacobsMetals]

Figured as much with the ratio. Should've probably done a 4:1 if that for the amount/grade of material but I went with what I was told was needed. I used a 1 gallon bucket for the material with only a 10th or so full of the fingers and pins (didn't do an initial weight since solution was based on volume) and covered then an inch or so above with AP. As for the silver pins, they're actually gold plated but have a nonmagnetic base metal that's silver in colour. Could be something else but with the age, brand, and amount of contacts I figured there's a good chance it's silver. Appreciate the info Andrew!

 

[JacobsMetals]

I'm currently adding pure copper along with some alloy to solution to try to cement any gold that might be left in solution and I'll drop the copper out after filtering using aluminum to get the copper back, refine, and leave the hcl for disposal. Next batch I'll use the copper and reset with clean hcl and peroxide at a better ratio.

 

[anachronism]

Why use copper without testing the solution for gold. Test test test.

Also if you still had metal in there the chances are that the black on the metal is any gold that's already precipitated out.

 

[JacobsMetals]

Basically giving up on first run. Let the copper overload the system and drive all the other metal that might be left out and saturate the solution completely. Then I at least can get pure copper from it when processing it for disposal and add that to next batch to start it and keep peroxide levels in check. I'm expecting all the gold is already out but I'll be left with more copper in solution and I'll check it before I run aluminum through it to drop copper. Have to gather some tin for the stannous still. Overall first batch is considered a failure and a lesson for next batch to be better. Total cost was $1 because I already had the hcl on tap for work so it's better for me to restart and get my levels perfected on a clean batch than try to level it all out now and end up with more volume.

 

[FrugalRefiner]

There are son many mistakes in what you're saying.

Basically giving up on first run. Let the copper overload the system and drive all the other metal that might be left out and saturate the solution completely. Then I at least can get pure copper from it when processing it for disposal and add that to next batch to start it and keep peroxide levels in check.

You're just going to waste copper. If you're going to be doing another batch, just use the copper chloride solution you've already created. Decant the solution off the solids and put your next batch of material into it. You avoid wasting the copper and the perfectly good copper chloride you've already created. You don't need any more peroxide. The copper chloride won't dissolve any of your gold in your next batch, and as any copper dissolves from your new material, it will push out any gold that may be in solution.

I'm expecting all the gold is already out but I'll be left with more copper in solution and I'll check it before I run aluminum through it to drop copper.

Using aluminum will not yield you pure copper. It will cement out everything below it in the reactivity series, so you'll end up with copper, any lead or tin that was in any solder, perhaps some nickel, etc.

Have to gather some tin for the stannous still.

That should have been your first step before you started any process. Refining without stannous chloride is like driving with your eyes closed.

Overall first batch is considered a failure and a lesson for next batch to be better. Total cost was $1 because I already had the hcl on tap for work so it's better for me to restart and get my levels perfected on a clean batch than try to level it all out now and end up with more volume.

No! You haven't lost any gold unless you throw it away. If you dispose of the first batch, then start a new batch, that's how you'll end up with more volume.

You really need to do a lot more studying before you proceed. Put this batch away safely, then start reading. When you understand what everyone is telling you in this thread, you can pull the batch back out and proceed.

Dave

 

[JacobsMetals]

I'm not too good with the chemistry for the AP but I thought the peroxide and hcl would decompose too much before next batch of scrap is ready since the excess peroxide also oxides the hcl and gives up the chlorine as a gas. Ideally the peroxide would break down but I figured itd break the hcl down before it gets out of solution enough. With the aluminum I know any other base metals will settle but my scrap was almost completely copper and silver with gold plating. Pins were cut above solder. So it would be relatively pure copper. Then the stannous I was hoping to get before moving on to the gold chloride step. AP wasn't supposed to affect the gold or silver so I didn't think I'd need to worry about it till I move on to the next step and of course test the AP then. I know the gold is fine, I just meant overall I messed up and next time I'll have a bit more experience to work it out better. I figured dropping everything out minus the aluminum would leave the hcl and aluminum to dispose of but if peroxide won't drop hcl levels and copper chloride is stable then I'll do like you said and just rerun the current solution for the next batch. Thanks for the info and advice Dave!

 

[Geo]

Once you create the copper(II) chloride, just bubble air through it and add fresh HCl when the solution turns black. You can use the same solution, pretty much forever. It's very hard to foul to the point that it no longer works as long as the PH is low enough and it has free HCl.

 

[JacobsMetals]

Thanks for the info Geo! That's my plan now. Also general update on my failed solution. I've filtered and cleaned the solids and the gold plating is at least partially intact as far as visible gold from fingers but it all broke down into a powder/glitter instead of leafs. Bigger pieces crumble when moved. So maybe it broke down a bit and broke the bond between the gold sheets as far as the fingers go but not to the extent of pure powder. Pins are black but hollow and extremely fragile (copper pins which were most of the pins, haven't found a silver pin yet but only checked a few, silver could also have broken out but not sure) so they appear to have possibly been dissolved then replated before the copper dissolved. Also forgot I had a gold wire in solution to see if it was actually pure or plated along with a plated wire (threw pure in mainly to not worry about it later and to add to final product). Plated wire blacked out and hollowed but gold wire stayed in same condition. So in the end the thin plating and too much peroxide lead to gold glitter but otherwise appears to have worked. So now I can purify or let the kids use it for arts and crafts.

 

[Geo]

If there is still base metal, the process isn't finished. Put any undissolved metal back, minus the gold foils already collected, in the CuCl2 and add a little fresh HCl and put the air back in it.