Pin Problems

[Yggdrasil]

I haven't personally tried it, but I think the idea of oxidizing the pins before any acid process is a good plan. It doesn't require much effort and could potentially expedite the subsequent steps, as oxidized base metals tend to dissolve more easily.

The issue here is as I see it that the part of the pins we would like to oxidize is protected by the Gold plating.
The AP attacks the all the Copper but also the Ni and other metals in there.
But usually we do not need to dissolve the whole pins the release the foils.
This way we can avoid to much mud and other gunk on the bottom to separate the foils from.
A Sulphuric Cell or Cyanide are often best if you have sufficient amounts to warrant starting up such systems.

I wonder, if smelting to anodes and electrolytic refining could be done with profit if the volume is big enough?

 

[Shark]

If you have a use for more copper it is worth trying a copper cell. The big factor is do you have time to add a long term process to your work space. I kept a cell setup and running for almost three years. I still have copper bars that contain about 5-6% gold waiting to be run. I use them to cement my waste with for now since I have slowed down. They are a bit more work to learn than a silver cell but also have a more diverse range as well.

 

[orvi]

I haven't personally tried it, but I think the idea of oxidizing the pins before any acid process is a good plan. It doesn't require much effort and could potentially expedite the subsequent steps, as oxidized base metals tend to dissolve more easily.

The issue here is as I see it that the part of the pins we would like to oxidize is protected by the Gold plating.
The AP attacks the all the Copper but also the Ni and other metals in there.
But usually we do not need to dissolve the whole pins the release the foils.
This way we can avoid to much mud and other gunk on the bottom to separate the foils from.
A Sulphuric Cell or Cyanide are often best if you have sufficient amounts to warrant starting up such systems.

I wonder, if smelting to anodes and electrolytic refining could be done with profit if the volume is big enough?

Roasting/heating the gold plated items is tricky endeavour as gold can very easily diffuse to the base metal underneath at higher temperature. And as Yggdrasil is correctly pointing out, before the diffusion takes place, not that much happens, as gold is protecting metals underneath.

If you heat treat the pins, you usually disabled them to be processed efficiently with AP solution. Eventually, you can smelt them, oxidize the zinc or tin in the brass/bronze out and then electrorefine copper.

But generally, if you can just strip the gold from the surface, that is usually the best option to proceed with. There are several methods for this, namely sulfuric acid electro-stripping cell, cyanide bath and iodine/KI leach. There are also commercial products like Eco-Goldex (which is masked cyanide stuff) to accomplish this.
Disadvantage is that only exposed gold will be leached. So any soldered parts or hidden plated parts (like top hat metal transistors) would be unaffected by this treatment.

I explained this several times - in ideal circumstances, with homogenous even material, which is only plated and all plating is exposed, you have plenty possibilities to go - with sulfuric stripping cell probably winning for smaller scale refiner. My material, which I refined regularly was mixed and always used, so pins were unsoldered, chips were soldered, plastic here, ceramic there... Stripping methods are worthless for this type of material.
Industry is mainly using stripping for nice material, any pyrometallurgy for whole PCBs and other stuff. Dissolving the bulk in acids is far from economical and nice

 

[Marcel]

OK, convinced. Roasting pins prior to AP treatment is a bad idea.

 

[Dreamer]

Unfortunately, the pins were liberated with a high speed grinder amalgamating the material. So dissolving it completely seems to be the only hydrometallurgical approach. After a couple of test runs, roasting and dissolving produced the best and quickest yeild. This has been a great discussion and I am very greatful for all the input. Learned much! I will post pictures and data when I finish.