Plated pins

[dcorley001]

Been saving for awhile and finally getting time to separate some materials. I've been sitting on these pins for awile. I had built a cell like Steves with parts ordered from him but with my schedule it will take a long time to finish. Had a little time today so I weighed out 31.5 grams of the material and placed it in a 600ml beaker with a 50/50 solution of Nitric and distilled water. There's a watch glass on top and it's in a secondary container in case of a boilover or worse. The solution volume was not calculated for the amount of pins. I've had the Nitric for awhile and wanted to make sure it would still handle the process. I also wanted to see what kind of color I would get. The solution is a beautiful blue after about 8 hours. Not a vigorous reaction but there was no heat applied. I intend to draw off some of the solution, add more pins and possibly some heat to gauge the volume of pins the bath will handle. When I dropped the pins in the Nitric there was a spot on the pins that turned almost black within a few seconds. I'm still getting a little bubbling and will chack them later today. Lots of tiny pieces of the gold plating though settling in the bottom of the beaker but there is also what appears a gray precipitate in the bottom. Everything appears to have settled. The pins have never seen solder. They were press fit in a large back plane and I think I still have another 5 pounds or so. Just looking for thoughts on the composition of the base material and treatment options once the bath is decanted. I will try to get some shots posted. Once this one is out of the way I've got a lot of pins to try or test but I plan to do them individually without mixing types. I've got the glassware to accommodate this but am still trying to get the lab I want put together. Thanks to all of you in the forum. the level of intelligence and experience here is unmatched!

 

[g_axelsson]

Grey precipitate in nitric is most often a result of tin in the material. The alloy of the pins are probably some sort of bronze. It could be a bit tricky to handle, clogging filters.
Tips of how to handle the tin oxides are all over the forum, just look for "metastannic acid" and you will find a ton.

Göran

 

[alvaschein]

Hi all

I read in Buth's book (german, "Gold aus PC und Handy") that it isn't worth while retrieving gold from all those pins you find PCB's. Well, just wondering if it is really true, I wanted to try how much gold I can get. So I took a bulk of plated pins (different types) and cut first the unplated parts and the parts with solder off to have a clean gold plated pin. For second I cut them into little pieces (about 2 mm) so the acid can work better on the centre of the pins.


I took 5 g of those chopped pins, put them into a 400 ml beaker and added 200 ml of water and 40 ml of nitric acid 65%. A very slow reaction started with tiny bubbles and a weak odour of nitrous fumes. The water/acid mix turned to a light blue.


The next day after about 12 hours all metals except the gold plate have dissolved. I filtered and washed the material an let it dry.


The resulting weight of this gold was about 0.28 g. So, extraploating on the 5 g input of pins, its gold content is about 5.6 %. Well, I didn't expect that. That proves that Buth was totally wrong on this point. The only disatvantage on my working process was, that I spent more than an hour to prepare the pins. But what do you want? It's hobby and not work.

Roy

 

[GOLDbuyerCA]

dcorley001n Readers. :> Your correct in saying pressed fit pins, they are actually valuable for Hobby builders, many pins of this type are 15 um flash platted, perhaps the best at 30 um. which if
they are all bent or wrecked, " unsalvageable for reuse" are scrap value. i say this, because, pins of this type are sought after, for use on proto board building, pic, below , shows plated pins Au. n palladium . i get requests from builders, " wire wrappers " quite often, depending on pin length, i have sold at 25 cents a pin to fifty cents a pin in 100 lot sizes. Also in the pic, please salvage, resell the small silver capacitors, the large ones the 3 in the pic, make good rings. but the small ones are coveted by builders of audio equipment. a lot of work pulling those pins out of back planes. photo included for discussion Cheers all. The 1702AQ's are now selling for 50 . fyi.

 

[Marcel]

@roy: Cutting off the gold plated parts surely increases the yield! The data for the yield was based on complete pins from PCI connectors, memory connectors aso. If you have the time to cut thoses parts off, you should also calculate time as an investment!
Look around in this forum, we have discussed the pin yields many times, you wont find anything higher than 1-2% for a full, uncut pin. lower than 1% is even more realistic.
The yield in my book was documented with an analysis from the Allgemeine AG (http://www.allgemeine-gold.de), Germanys largest and most competent refiner. Their labatory reported 0,1%-0,2% Ag and 0,1%-0,2% Pd back.
Last but least, it is not accurate enough just to weight the foils! You must dissolve the foils and then precipitate and then weight again! You will wonder how much mass they will loose in this refining step. The foils are by far pure gold. They often contain nickel, copper and other alloyed metals. You only weighted the raw mass of the recovery.
So we must compare under equal conditions: Use your goldpins without prior cutting them, just as they are. Dissolve the foils and precipitate the gold. Then weight the result and tell us again what your yield is.
I bet it will be rather 0,56% than 5,6%.

Marcel

 

[alvaschein]

@Marcel: From this point of view, you're absolutely right!

For me time is not a factor. When I have spare time I do crazy things like chopping pins. It's just for hobby, not for living.

Roy

 

[goldsilverpro]

Your correct in saying pressed fit pins, they are actually valuable for Hobby builders, many pins of this type are 15 um flash platted, perhaps the best at 30 um.

To prevent confusion on the forum, I must correct your usage of the term "um". The approximate thickness of the gold is actually 15-30 microinches and not 15-30 um. The term "um" means microns and one micron equals 40 microinches. Therefore, 15-30 microinches would be only 0.375 - 0.75 um.

 

[solar_plasma]

Especially pci-pins have often only gold plating on one side 1x2 mm. Can I expect 0,5% gold from the whole pin? Sounds too much to me...

Has anybody experienced how much or how often there will be palladium on them? Or are the shiny silver ones always nickel?

Btw I mostly get them one by one, I try to avoid metal dust and fumes.

 

[ritehere]

so how exactly would you get the gold back out of the muddy grey material. Would filtering and washing in hcl be a way to do so?

 

[patnor1011]

I would love to see over 5% yield from pins mainly when I look at my about 10 kilograms of them. :lol:
If you attempt to AR your foils from 5 gram of pins then you will have problem to see any powder no matter how much smb you will use.
Do not put your stuff to HCl after nitric treatment without proper incineration first.
There are literally thousands of posts about how to process pins or what to do with them.
My advice is to start researching H2SO4 reverse electroplating cell for processing pins. Computer pins are pain to process by dissolving them whole in acids. I would say that that is very expensive method - it all depend how much do you pay for acids and how do you intend to treat waste.