Non-Chemical Gold covered Steel Parts

[klamp]

I have a large amount of old glass resistors, well a few pounds, that can be picked up with a Magnet , so I think they are steel core
I tested these and they are gold coated, What is the best way to recover the Gold from these ? I wanted to try AP but was scared to because of the steel content.
(Top picture is the part, penny is just for size, below is resistor taken apart ready to be scraped)
I'm new at this and have not tryed to recover yet, I have read Hoke books and have done a lot of reading here also, of course I can use more help !!

 

[FrugalRefiner]

They may or may not be steel. Gold plating will migrate into base metals like copper and brass over time, making the plating less effective. For this reason, there is usually a layer of nickel plated onto the base metal, then the gold is plated onto the nickel as it doesn't migrate into nickel as easily. The nickel layer can be attracted by a strong magnet.

Use a small file to create a deep notch in the wire and look at it under a good magnifier. You should get a better idea of what you're dealing with.

As always, check to see if they have any value to collectors or those who restore vintage electronics.

Dave

 

[klamp]

I have seen these up on ebay with big price tags but no one buying, I'v had these back to 70's and it's time to scrap
Would something like Muratic acid, and hydrogen peroxide work ?
From my reading so far this doen't look like it would dissolve the base metal
I hate to use Nitric Acid, thats why I was looking for a pro here thats done this and had good luck.

 

[Pantherlikher]

AP 1 and find out. Wost that happens is...nothing...

 

[klamp]

yea, a small test batch looks in order then , thanks :roll:

 

[Palladium]

Using logic that if it's used for electricity i would bet that the leads are not iron.

 

[g_axelsson]

There is a lot of iron and iron alloys used in electronics. Just check the kovar leadframes or pins on modern through hole mounted transistors and diodes.

Göran

 

[Palladium]

Where the conductors have to go through the glass envelope of the dewar, the use of Kovar as a conductor material is indicated. The reason for this is that Kovar readily forms an oxide coating which bonds firmly to glass, and is used as the interconnect material because of its matched thermal expansion to that of glass and because of its relatively low heat load across the thermal interface.

I assumed copper, but having gone back and done some research i have learned that it's highly likely your right. Scratch it real hard with something and see what the base metal color is.

 

[klamp]

I guess maybe tin ?
I use a "super magnet", a normal magnet is "a weak Magnetic field"
In my research I found this, "In addition to the age, as a rule of thumb if the gold plated pieces or gold plated parts are magnetic they are usually more valuable than non-magnetic based gold plate because the manufacturers usually plate more gold on magnetic based parts than on copper/brass based parts."
I do know only two things for sure , they are old and they are heavy plated gold, next step is the find a good way to refine the gold.
(when I scrape off some of the coating it's white- shine "steel" like color under the plating) The leads bend easy also, not stiff

 

[etack]

(when I scrape off some of the coating it's white- shine "steel" like color under the plating) The leads bend easy also, not stiff

This sounds like Ni then. take a strong magnet and see what the speed of the attraction is Ni is slower than Fe. Also most of the iron leeds I've run into on Tantalum caps are CuFe clad. They will have an Iron core and Cu shell. this type of leed is always stiffer. The leeds that bend easily are Ni.

Do some quick surface area calculation to see which way you will make the most money. Those leads are stupid simple to calculate.

This is sams and it is a good one to use. http://www.goldnscrap.com/index.php/calculators/72-gold-plating-calculator

Eric

 

[klamp]

0.0320in or 20AWG
each part leads are 1.5in X 2

Would the Muriatic Acid / Hydrogen Peroxide method used to recover from base metal copper work with these ?

 

[klamp]

Well, I got my answer on another Forum

"Ferrous metals will vastly reduce the effectiveness of chemical bath 1, the resulting pulp will not re-precipitate any gold in the final step. For magnetic conductors use Aqua Regina." :!:

 

[etack]

I think you missed what I said in my post you have described them to be Ni not Fe based. you should use a cell or nitric NOT AR.

they look to have $0.12 worth of Au each in them @ $1385 TOz Au

Eric

 

[klamp]

Looks like I'll be ordering nitric and not Aqua Regina, I don't have either one on hand anyway,
Thank's very much for the infor, it's saved me lots of time

 

[jimdoc]

Looks like I'll be ordering nitric and not Aqua Regina, I don't have either one on hand anyway,
Thank's very much for the infor, it's saved me lots of time

You don't order aqua regia, if you do someone got over on you.

Jim

 

[etack]

dilute sulfuric will work too.

Sulfuric can be nasty stuff.

Eric

 

[klamp]

aqua regia not needed, no need to order concentrated nitric and hydrochloric acid, thats what I should have said

Here is the plan I'd like to try, as I am new to this..........
REFINE WITH JUST NITRIC ACID, made with SODIUM NITRATE and BATTERY ACID/ ELECTROLITE
I know this is not the right place so I'm not going into details here
This way I "CANNOT LOSE ANY GOLD BY MAKING A MISTAKE!"
This should " DESOLVE ALL METALS EXCEPT FOR GOLD"
FILTER TO CATCH THE GOLD and fire.

what do you think?

 

[butcher]

Sounds like a good plan to recover the gold, although I would then refine the gold before melting it.

If you are still unsure of the base metal involved an experiment on a small amount in a small jar, this can give you an idea what to expect before you commit to the large batch.

I would guess it is just copper and the nickle is drawn to the strong magnet.

 

[klamp]

Thats sounds like I good idea, as long as the more "pro" guy's in here agreed with this type of refine step, the NITRIC ACID I mean
remember, I'm just a "newbie" and wide open to any throughts, of course I'm not trying to get "spoon fed"