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Geo

Well-known member
Joined
Mar 1, 2011
Messages
7,070
Location
Decatur,Ala.
I am doing a refine for a gentleman that sent me some contact pins that have tiny points. The pins had a silver color but testing showed the pin were coated in tin. The points are a karat gold that contains silver. Percentages are unknown but the silver to gold ratio is very low. I would estimate at less than 3% silver by weight. This could be skewed because the final clean up of the points was done in hot dilute nitric acid.

100_1773.JPG

contact 2.jpg

contact 1.jpg

100_1746.JPG

100_1747.JPG
 
Nice!

I think I have seen something similar some time. But the contact point are tiny, how much pins did you need for 32 g of points? It must have been many kilos.

... time to try finding my stash. I should still have mine somewhere. :D

Göran
 
There was 12.5 kg of pins total and the amount in the pic is about half of the points. It's looking like there may be 2 ounces total.
 
That's quite a job to process. I probably only have less than 100 grams of pins. Never had a lot of it.

Thanks for the information.

Göran
 
snoman701 said:
You did 12.5 kg of pins in nitric?

Holy nox


Sent from my iPhone using Tapatalk

Sno
I think Geo only did the final clean up in nitric not the whole amount...
 
nickvc said:
snoman701 said:
You did 12.5 kg of pins in nitric?

Holy nox


Sent from my iPhone using Tapatalk

Sno
I think Geo only did the final clean up in nitric not the whole amount...
I'd hope not!

Mostly because it's like Be Cu


Sent from my iPhone using Tapatalk
 
I removed the tin with muriatic acid and then dissolved the pins in copper(II) chloride. There was a lot of CuCl crystals that took a couple gallons of fresh HCl to dissolve and then I washed the points in a solution of sodium hydroxide. Followed that with some water boils and then dilute nitric acid to clean the points up nice and clean.
 
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