contact pins

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Geo
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contact pins

Post by Geo » June 14th, 2018, 10:44 pm

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.
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contact 2.jpg
contact 1.jpg
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g_axelsson
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Re: contact pins

Post by g_axelsson » June 15th, 2018, 11:32 am

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

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Geo
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Re: contact pins

Post by Geo » June 15th, 2018, 12:45 pm

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.
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g_axelsson
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Re: contact pins

Post by g_axelsson » June 15th, 2018, 4:41 pm

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
Visit the GoldRefiningWiki, an online refining encyclopedia.
It also contains an online version of the book "Refining Precious Metal Wastes" by Hoke.

snoman701
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Re: contact pins

Post by snoman701 » June 15th, 2018, 9:15 pm

You did 12.5 kg of pins in nitric?

Holy nox


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nickvc
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Re: contact pins

Post by nickvc » June 16th, 2018, 2:57 am

snoman701 wrote:You did 12.5 kg of pins in nitric?

Holy nox


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

snoman701
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Re: contact pins

Post by snoman701 » June 16th, 2018, 1:03 pm

nickvc wrote:
snoman701 wrote:You did 12.5 kg of pins in nitric?

Holy nox


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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


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Geo
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Re: contact pins

Post by Geo » June 16th, 2018, 9:05 pm

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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