Gold plated pins

[Rreyes097]

So my past tries with plated pins have been unsuccessful except when I used reverse electro plating. But my attempts with AP and gold plater pounds haven't worked. This is because I didnt know about using nonmagnetic pins. So my question is can I use the semi magnetic pins? If so what do I have to know? I want to use ap process, is there anything that is different from processing gold fingers?

 

[jason_recliner]

Magnetism is not what's important. And it's quite different from AP process.

Gold fingers are a thin layer of Au, on a thin layer of Ni, on a thin layer of Cu.
Pins are a thin layer of Au on a thick chunk of Cu, and possibly with Be, Fe and maybe Co thrown in for good measure.

If you're going to use AP CuCl₂ leach, you have to dissolve ALL the base metal.
This is why many pins are better suited to recovery via the sulphuric cell process. Dissolve the gold, discard/sell the base metals.

 

[worldavi]

If the pins are clean, why cant they just be put into a solution of Muratic Acid and slowly adding the bleach, disolve only the gold into the solution? Will that work or not? Seems to me the gold will go right to the solution and next thing strain out waste and precipitate? If not please explain why.

 

[worldavi]

I have about 10 lbs of pins and contacts from much of the avionics equipment from the 60's and 70's. Some of the circuit boards all the runs are plated gold. Cant the gold just be leached to solution with the HCL and Bleach?

 

[jason_recliner]

Gold will not remain in solution while there is any base metal present. This is a fundamental principle.
So no.

 

[patnor1011]

I have about 10 lbs of pins and contacts from much of the avionics equipment from the 60's and 70's. Some of the circuit boards all the runs are plated gold. Cant the gold just be leached to solution with the HCL and Bleach?

Nope. As it was pointed out previously any gold dissolved will immediately precipitate on top of any other metal submerged in the mix. It will be looking like dark stain and superfine dark powder which will cling to everything in there.

 

[worldavi]

Thanks for reply....just to clarify as I think I got this straight. When using AR or HCL and Bleach, the only material that should be put into that solution is material which is basically "free" of any base materials. IF not, we are just dissolving the gold and remaining base metals into the AR solution.....and when precipitated.....we will get powder that is a mixture of gold AND base metal......WHICH puts us back at square 1 again. Right?

And when using HCL and Hydrogen Peroxide....the Peroxide is mainly used as an oxidizing agent to speed up the process of the HCL action against the gold plate and base metals? Some people use an aquarium pump to oxygenate the HCL instead of using Peroxide?

What base materials will HCL consume? Am I correct in thinking only NON PM's? If we suspect that there may be other PM's such as silver or platinum with the gold, then to remove those we need to switch to the use of Nitric since that will absorb silver and not gold. Will Nitric absorb base metals AND silver?

 

[goldsilverpro]

To test pins, I would always use an ordinary Alnico magnet, but never use a strong neodymium magnet. If an Alnico magnet doesn't stick, the pin is copper based. If it does stick, it's either nickel, cobalt or iron based or, more likely, all 3 (as found in Kovar).

Most all gold plated pins have a layer of nickel between the gold and the base metal. The thickness of the nickle can vary considerably, depending on the manufacturer. Especially when the Ni is thick, a super strong neodymium magnet, as found in hard drives, will stick to it. This will give a false reading when the pin is copper based.

The Alnico won't pick up a copper based pin, unless the nickel is super thick, a case that I've never run into.

 

[worldavi]

To test pins, I would always use an ordinary Alnico magnet, but never use a strong neodymium magnet. If an Alnico magnet doesn't stick, the pin is copper based. If it does stick, it's either nickel, cobalt or iron based or, more likely, all 3 (as found in Kovar).

Most all gold plated pins have a layer of nickel between the gold and the base metal. The thickness of the nickle can vary considerably, depending on the manufacturer. Especially when the Ni is thick, a super strong neodymium magnet, as found in hard drives, will stick to it. This will give a false reading when the pin is copper based.

The Alnico won't pick up a copper based pin, unless the nickel is super thick, a case that I've never run into.

The contacts that I have are large some weigh 4 grams. We use these in avionics testing and in the black boxes that plug into the aircraft racks. I think the gold covering these are thick as they were made in the 60's 70's. What is the best way to remove the gold without using Nitric? Can HCL/Peroxide work well heated slightly?

 

[kernels]

Thanks for reply....just to clarify as I think I got this straight. When using AR or HCL and Bleach, the only material that should be put into that solution is material which is basically "free" of any base materials. IF not, we are just dissolving the gold and remaining base metals into the AR solution.....and when precipitated.....we will get powder that is a mixture of gold AND base metal......WHICH puts us back at square 1 again. Right?

And when using HCL and Hydrogen Peroxide....the Peroxide is mainly used as an oxidizing agent to speed up the process of the HCL action against the gold plate and base metals? Some people use an aquarium pump to oxygenate the HCL instead of using Peroxide?

What base materials will HCL consume? Am I correct in thinking only NON PM's? If we suspect that there may be other PM's such as silver or platinum with the gold, then to remove those we need to switch to the use of Nitric since that will absorb silver and not gold. Will Nitric absorb base metals AND silver?

No, not quite.

You will not successfully leach gold from pins using AR or any similar combination because the gold dissolves into solution, but then because there are base metals in contact with the solution, the gold cements out onto the base metals as it is replaced in the solution by the base metal molecules.

There are really only two ways to do this, reverse-plating (sulfuric cell) or a leach solution that leaches only the gold (usually cyanide based). I believe you also want to have a look at the eco-goldex thread that is floating around. My understanding is that it is a gold leach that is safer than the usual cyanide leaches.

 

[worldavi]

Thanks for reply....just to clarify as I think I got this straight. When using AR or HCL and Bleach, the only material that should be put into that solution is material which is basically "free" of any base materials. IF not, we are just dissolving the gold and remaining base metals into the AR solution.....and when precipitated.....we will get powder that is a mixture of gold AND base metal......WHICH puts us back at square 1 again. Right?

And when using HCL and Hydrogen Peroxide....the Peroxide is mainly used as an oxidizing agent to speed up the process of the HCL action against the gold plate and base metals? Some people use an aquarium pump to oxygenate the HCL instead of using Peroxide?

What base materials will HCL consume? Am I correct in thinking only NON PM's? If we suspect that there may be other PM's such as silver or platinum with the gold, then to remove those we need to switch to the use of Nitric since that will absorb silver and not gold. Will Nitric absorb base metals AND silver?

No, not quite.

You will not successfully leach gold from pins using AR or any similar combination because the gold dissolves into solution, but then because there are base metals in contact with the solution, the gold cements out onto the base metals as it is replaced in the solution by the base metal molecules.

There are really only two ways to do this, reverse-plating (sulfuric cell) or a leach solution that leaches only the gold (usually cyanide based). I believe you also want to have a look at the eco-goldex thread that is floating around. My understanding is that it is a gold leach that is safer than the usual cyanide leaches.

Thanks Kernals. Interesting...So what would happen to the pins/contacts if placed in HCL/Peroxide solution? Would the gold not be left behind as flakes and the base metals be consumed, as happens with PCB card edge contacts and DIMM contacts? Is it because there is a higher base metal content within each pin/contact than a circuit board trace?

 

[kernels]

Thanks Kernals. Interesting...So what would happen to the pins/contacts if placed in HCL/Peroxide solution? Would the gold not be left behind as flakes and the base metals be consumed, as happens with PCB card edge contacts and DIMM contacts? Is it because there is a higher base metal content within each pin/contact than a circuit board trace?

So, the pins that are only slightly magnetic like you usually get from PCI connectors or IDE connectors have Brass / Bronze / other copper based alloy as the base metal.

You can process these pins with AP (C2C) to remove the base metals, then you will (after a while) be left with the gold 'tubes' - There is a user named Tzoax who has posted a thread on doing exactly this, have a search and see if you can find it.

The real problem is that you have to dissolve a large amount of base metals for a small amount of gold, then you have to treat the waste acid that you create, which is the real pain with gold recovery. The process is also reasonably slow, because the acid can only work on the exposed base metal surface, so it has to hollow the gold tube out from the sides inwards.

So, in theory, yes, it will and does work. In practice, I wouldn't create the waste for the amount of gold I'm going to get back.

That basically then leaves you with trying to remove the gold without having to dissolve the base metal, which leads you back to cyanide leaches or a Concentrated Sulfuric Cell.

 

[kernels]

Here is a link to Tzoax's thread where he processes mixed pins with Acid-Peroxide.

http://www.goldrefiningforum.com/~g...24012&p=254122&hilit=tzoax+mixed+pins#p254122