recovering gold from gold plated magnet wire

[geoffB]

I am a newbie to recovering gold so of course I have a difficult problem to overcome. (maybe it's not difficult- i am a newbie)
I have about 3 pounds of very fine (48AWG) gold plated magnet wire. The wire is 0.0015" diameter copper plated with gold and has a hard enamel coating. I think there is a signifigant amout of gold on all that wire. 3 pounds doesn't sound like much but because of it small diameter there is probably a few miles of wire length. This wire used to be used to connect the hard drive head to the electronics. The wire ran from the head along the arm and to the electronics. These wires were used many years ago but have since been replaced by a flex circuit PCB. I am looking for the best way to breakthrough the enamel coating and seperate the gold from the copper. Any help would be greatly appreciated.

 

[cnbarr]

Try soaking a small test batch in sodium hydroxide (caustic soda), this may eat through the enamel coating? Although I have never heard of "gold plated magnet wire" .?

 

[Geo]

i have a question.are you sure its gold?

ive never seen copper coated gold wire or any copper coated gold anything before.

why would anyone want to coat gold with copper?

 

[nickvc]

i have a question.are you sure its gold?

ive never seen copper coated gold wire or any copper coated gold anything before.

why would anyone want to coat gold with copper?

I tend to agree with Geo but if your sure it has a gold content melt a small amount into a button and dissolve in diluted nitric acid, the melting should remove the enamel and the nitric will dissolve the copper so in theory what left should be gold.

 

[geoffB]

Thanks for the replies. I did not say it was copper plated gold wire. I said it gold plating over copper wire with the enamel coating. The insulation makes it "magnet wire". The term "Magnet wire" is from the transformer industry that uses copper wire with the enamel coating to wind transformers and chokes.
Last night I placed a small amount of the (gold plated copper) wire in a crucible and was able to melt the wire into a ball. It looked like the enamel coating just burnt into ash. I just have to seperate the gold from the copper now. I guess nitric acid is the answer. If anyone has some helpfull hints it would be greatly appreciated.
Thanks for the help
Geoff

 

[geoffB]

I though of a few more questions.
What concentration of nitric acid do I need?
What do I buy to dilute it?
What concertration do I put the Cu/Au?
Is it better to make many small button or a few bigger buttons of Cu/Au?
thanks
Geoff

 

[glondor]

That first photo really looks like copper to me. There are several ways to qualify the material for processing. If you want to "see" what you have do this>>> I guess the best thing to do would be to incinerate. Do not melt. Just get to a red heat. burn off all contaminates. Look up incinerate in search. Butcher and Harold have many good posts on incineration. Follow their instructions on that matter. I would use a 250 gram sample, enough material to see what you have when you are done. The fine wires should dissolve in nitric very fast and vigorously, (If you melt into a button you are making your task harder to dissolve) so use at least a 2 liter beaker and proceed with care. It will take 1 liter of 67% 50/50 nitric to do the job. Do not go over the 400 ml mark with liquid in a 2 liter beaker. If you stay under the 400 mark the risk of boil over is cut by a large margin. Not to say it cant happen tho. Add water and acid in small increments, decant as necessary and add more until all that will dissolve is dissolved. A small amount of heat may be necessary near the end Monitor carefully. Do not do this indoors without a proper fume hood. Emphasis on DO NOT. The fumes will kill you or cripple your lungs for life. What you have left should be of interest. If there is anything left, let us know and we will advise from there. Good luck!

If you want to "see an indication" of what you have do this>>>> Dissolve a small incinerated sample in a small amount of A/R. Denoxx. Be sure to denoxx or it will invalidate your test. Test solution with Stannous chloride. Purple to black is good. ( + test)

Maybe do method 2 first to see if there is gold then method 1 to see how much gold there is.

 

[glondor]

The best thing to dilute your nitric is distilled water. Tap water is OK but may introduce chlorine to your effort which "may" result in some colloidal gold. Not sure about this yet.

 

[Geo]

geoffB,

what is your chemistry background? have you ever worked with chemicals before?

never work with nitric acid indoors unless you have a fume hood. When you dissolve metal with nitric acid, nitrogen dioxide is produced which is extremely poisonous and can harm you with even light, small exposure that may never heal.

AR (aqua regia) produces the same gasses. I cant stress enough how dangerous this stuff is as it can effect your health for the rest of your life.learn the processes before you attempt any of this.

be safe. good luck.

 

[stihl88]

In my experience with Magnet Wire i would bet London to a brick that it is not Gold plated wire.
Usually the different colors of Magnet Wire are represented by thermal rating, fire rating etc.

I wouldn't waste your time with this wire...

 

[geoffB]

I know for a fact that it is gold plated wire.
Just to make sure I used the XFR at work to verify it.


I have done some handling of acids. I know to do things in under a hood or outside with something to draw away fumes. Not so much because I know what gases are comming of the solution. More because it is common sense. I have acid handling equip at work with a good fume hood.

 

[Harold_V]

If the wire is gold plated, there's likely a layer of nickel under the gold, which prevents migration of the gold plating in to the copper.

A simple test would be to incinerate just a small piece of the wire, to eliminate the varnish. Cutting it in short pieces will likely hasten the reaction of dissolving the core, which you'd do with heated dilute nitric. If the exterior is gold plated, it will remain as solids, maybe even as fine tubes of gold. In any event, when the cores has been digested, the gold, regardless of how it may manifest itself, will remain as a solid. No solids---no gold.

Harold