# Best way to process this



## goldscraphobby (Mar 29, 2014)

Hi,
I have some Milspec space application gold plated housings. . Some are large (8"x11") and complicated (~2" high and cavities on both sides), lots of walls, holes, cutouts etc.

I am planing on using a sulfuric cell but looking for other ideas or suggestions.

How deep can the sulfuric cell be? Because of the size how large a power supply would it require?

There is no rush so if there is another less intensive static process I would do that- Iodine?

Will this deplate evenly with all the different machined areas? How long would something like this take to deplate?

Would the cell generate a lot of heat? If so, can the bottom of the cell be connected (like a drain) to another container- the acid, along with the gold, can drain into it, the gold settle out, the acid cooled and returned to the cell constantly to reduce the heat and also the cell would not need to be disturbed for cleanout.

Please let me know whatever you are thinking

Thanks
GSH


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## necromancer (Mar 29, 2014)

i would chop that up with a band saw.

if you don't have one, try your local high school. they will chop it up for free


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## joubjonn (Mar 29, 2014)

You want to use the least amount of sulfuric as possible with a cell. That acid scares me. And yes it will heat up depending on how big the volume is, the amp draw, how long the part is stripping, etc. all your answers are covered in the search box. Chopping it up would be the best way to deal with. But I would check that base metal isn't something like Berillium copper which makes some very toxic dust when cut.


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## jimdoc (Mar 29, 2014)

Ebay would probably bring in the most money.
They buy everything for far more than it's worth.
You just want to estimate the worth for your reserve.

Jim


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## necromancer (Mar 29, 2014)

if it is a mil spec from a space project, copper would be to heavy, i say its 6061 t6 aircraft alloy. or something like it.



> 6061-T6 aluminum is commonly used in aircraft construction. Although primarily used in private rather than commercial aircraft, its strength-to-weight ratio is very high, making it ideal for large parts that need to be very light, such as the plane’s fuselage and wings. This light weight also made 6061-T6 aluminum the best choice for the famous gold-anodized plaques that were mounted on board the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft.



http://www.sapagroup.com/en/na/profiles/6061-t6-aluminum-properties/


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## g_axelsson (Mar 29, 2014)

It looks like aluminum base metal. If it is and the gold is plated, there has to be a copper layer first before the gold is plated.
A quick wash in nitric acid dissolves the copper but leaves the aluminum and gold unaffected.
After the piece has been washed in nitric and the gold foils are loose you was the aluminum in water, then it's a simple matter to collect the gold foils from the wash water and the nitric.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=19177&start=20#p194541

Göran


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## necromancer (Mar 29, 2014)

g_axelsson said:


> It looks like aluminum base metal. If it is and the gold is plated, there has to be a copper layer first before the gold is plated.
> A quick wash in nitric acid dissolves the copper but leaves the aluminum and gold unaffected.
> After the piece has been washed in nitric and the gold foils are loose you was the aluminum in water, then it's a simple matter to collect the gold foils from the wash water and the nitric.
> 
> ...



i would like to suggest that the title in linked post be fixed, there is no searching that spelling (sorry)


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## Irons (Mar 29, 2014)

Once, at a University where I was on Staff, we acquired some Ballistic Missile logic units that were encased in Beryllium. They were very similar to what was shown in the image. The Gold plating was to prevent oxidation of the Beryllium, which is a severe health hazard. The reason Beryllium was used was that it protected the logic modules from Thermal Neutron Radiation from the Warhead. Sawing it or putting it in solution would be a very bad thing to do. JM won't even accept material that even has a trace of Beryllium in it. I suspect other refineries have a similar policy.

Beryllium is very light and might be mistaken for an Aluminum Alloy.


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## necromancer (Mar 29, 2014)

Irons said:


> Once, at a University where I was on Staff, we acquired some Ballistic Missile logic units that were encased in Beryllium. They were very similar to what was shown in the image. The Gold plating was to prevent oxidation of the Beryllium, which is a severe health hazard. The reason Beryllium was used was that it protected the logic modules from Thermal Neutron Radiation from the Warhead. Sawing it or putting it in solution would be a very bad thing to do. JM won't even accept material that even has a trace of Beryllium in it. I suspect other refineries have a similar policy.
> 
> Beryllium is very light and might be mistaken for an Aluminum Alloy.



great information, i never would have known. thanks again Irons !!


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## goldscraphobby (Mar 29, 2014)

Hi,
Its aluminum, electroless nickel than gold plate. No copper or Beryllium.

If I have to cut it up I will but would like to avoid that, A lot of metal to cut. Not afraid of the acid, will take necessasry precautions. I was thinking of a cell like below. Just thinking.

Has anyone attempted something this large in a cell? If there are issues then I will resort to cutting it up

Not looking to sell it, just want to recover the gold for my own satisfaction


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## goldsilverpro (Mar 29, 2014)

I, for one, wouldn't want to continuously pump concentrated sulfuric. I can't see what you would gain. Why not just use the bottom tank sitting in ice as the stripping tank and forget about the circulation.


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## goldscraphobby (Mar 29, 2014)

I wasn't sure how hot it would get and also wouldn't have to take it apart as often to clean out the gold.

Wondering if anyone has ever tried to strip this large a surface with a cell and how big a supply it would require.


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## goldsilverpro (Mar 30, 2014)

What are the dimensions of that piece?


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## joubjonn (Mar 30, 2014)

I think he said 8in x 11in. Big piece for sure. So much acid either way unless you cut it which could be bad. 

Berillium copper is also used in the oil and gas industry for wireline service tools. Like MWD (measuring while drilling) or LWD (logging while drilling). Those tools usually have a neutron source and must take high heat and pressures. Makes sense. 

Apparently the company I work (I'll call the company Big Red, nickname) for has a big vault of radioactive sources for those wireline tools. Had some training on it a few weeks ago.


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## eastky (Mar 30, 2014)

Just a thought. If I had that I would get some purple power degreaser or grease lightning degrease and soak it in that.

If it is aluminum with a nickel plating under the gold score the plating in some spots so the degreaser get to the aluminum.
I believe the degreaser oxidizes the aluminum and the plating will release because of the oxidization.

Search the net for removing anodized coatings from aluminum parts. To understand what I am talking about.


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## goldscraphobby (Mar 30, 2014)

Its ~ 8"x11" with the cavities on both sides, see photo in 1st post.

I have many other plated pieces so I think I just need to make a cell and see how it goes.

I will look up the degreaser angle and see how that might work

Any other suggest are welcome

Thanks for the info


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## g_axelsson (Mar 30, 2014)

goldscraphobby said:


> Its aluminum, electroless nickel than gold plate. No copper or Beryllium.


According to http://wwwchem.uwimona.edu.jm/courses/nickel.html nickel is soluble in dilute nitric acid so it ought to work to dissolve the nickel to release the gold.
At least I would test that road before building a large sulfuric cell.

I don't have any Al-Ni-Au object so I can't test it myself but I would like to know the outcome if someone tests it.

Göran


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## goldscraphobby (Mar 30, 2014)

Thanks,

Any thoughts on a source of nitric? I'm near philadephia.

I do have some very old nitric, around 16 oz. It was lab grade but has been sitting around a long time. 

What is considered dilute and how to go about it?

Thanks


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## Anonymous (Mar 30, 2014)

Guys it's Aluminium. 

Aluminum was an spelling error made by Noah Webster in 1828 that has somehow "stuck" in the US.

Sir Humphry Davy actually settled on the name Aluminium in 1812.

I've got my tongue planted firmly in my cheek when I say this but us Brits all find it funny that you guys keep mis spelling and mis pronouncing the name of this element. :twisted: :twisted: :lol:


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## Geo (Mar 30, 2014)

You may be able to make what you have work. Using a plastic tub as a cell and a piece of stainless steel as the cathode and your work piece as the anode, the nitric you have may work ok as the electrolyte. The electrolyte should work ok at around 10% tech grade. It should work quicker than a passive bath would. I would go with low voltage and low amps and increase until the stainless starts looking like copper.


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## Geo (Mar 30, 2014)

It's ok spaceships, most everything a person from "across the pond" says here gets a chuckle. :lol:


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## Anonymous (Mar 30, 2014)

Haha good answer mate. 8)


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## joubjonn (Mar 30, 2014)

Don't forget to tell us the yield on that. Should be pretty good I would guess.


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## necromancer (Mar 30, 2014)

goldscraphobby said:


> Thanks,
> 
> Any thoughts on a source of nitric? I'm near philadephia.
> 
> ...



if the bottle is closed tight you should be ok. put a drop on a piece of copper, if there is a good reaction your nitric is good
(do this outdoors) away from people & pets

dilute nitric.....
ad nitric acid @ 70% to equal amount of water = 35% nitric acid. (50/50 nitric) always ad acid, never ad water to your acids


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## pgms4me (Mar 30, 2014)

I have some similiar housings like that. They are RF amplifier housings,except mine are silver plated. I have no idea what to do with them. they are about the same size 8" x 12" x 4" The base metal is close to 6061 aluminum. Any ideas??


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## necromancer (Mar 30, 2014)

i see a number on the photo in the OP
it's 9407-1 what other info is there that i can look up?


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## goldscraphobby (Mar 31, 2014)

That number was stamped on by the machine shop. No other markings- I would have to double check what class thickness the plating was by I think it was a minimum 150 to 300 max micoinches and no brighteners

I'll take a small one and throw it into the dilute nitric, let it sit and see what happens.


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## nickvc (Apr 1, 2014)

If this was mine I know exactly how I'd strip it but that route isn't one I wish to promote.
As hydrochloric is cheap and easy to obtain why not expose the core and dissolve the aluminium leaving the foils for a final refining where your nitric will be useful, aluminium will react very violently with the acid so I'd be tempted to start with the items in water and slowly add the acid, I'd start with a small item first to be able to control the reaction and gain an understanding of how much acid to add at each addition and also to see if its worth the effort. Please note this reaction will produce volumes of fumes so a good hood or doing it outside and with a fan or wind behind you is a must.


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## pgms4me (Apr 1, 2014)

Those look almost exactly like my silverplated ones. They weigh 6-10 pounds each. That is a lot of aluminum to dissolve. Sodium hydroxide would also dissolve the aluminum. Might even be more cost effective?


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## goldsilverpro (Apr 1, 2014)

goldscraphobby said:


> That number was stamped on by the machine shop. No other markings- I would have to double check what class thickness the plating was by I think it was a minimum 150 to 300 max micoinches and no brighteners


As long as you're going to dream, you may as well dream big. How on earth did you come up with those thickness numbers? I would be very surprised if they even ran 50 micro". Unless you can post an official reference saying the gold on that exact part is 150-300 micro" thick, I'll never believe it. For your sake, though, I hope you're right, but the odds are against it. There's only one way to find out - stop talking about it and start processing. A couple of years ago, I visited a place that had several gaylords full of these exact same parts of various sizes, both the gold plated and the silver plated variety. Some had covers on them. Most were an aluminum base and some were of a copper alloy base. None of the gold ones even got close to those thicknesses you speak of. When you own the material, it's human nature to believe the highest numbers you can find anywhere and jack up the value in your mind. I've done it myself, more than once.

I would definitely use the sulfuric stripper but I would cut up the part in about 3"x4" pieces. The sulfuric stripper works fine on aluminum without attacking it, assuming you run it properly and don't use too much current and get the solution too hot (not over 110F). To do this, I would suggest not exceeding 5A/gallon. The stripper works fine with low current. It's just a little slower. You never need lead cathodes in the sulfuric stripper. Just use 2, 1/8" pieces of steel sheet as cathodes wired together, one on each side of the anode. I would make the cathodes about twice as big as the anode. 

With any electrolytic system, the current is not applied evenly on the part. Protruding areas get the most current and the cavities get the least. The cavities will likely strip last. However, these were plated electrolytically and, therefore, the gold is probably thinner in all those cavities than on the outer surfaces, unless they used a conforming auxiliary anode in each cavity, which is very unlikely.

There is most probably a nickel layer between the Al and the Au. They wouldn't use copper because of the Au/Cu migration problem, although Cu could be used between the Al and Ni. I've never seen Au plated directly on Al. The no brightener gold sounds reasonable. When brighteners are used (usually small amounts of Co or Ni), the gold purity is lowered (usually to about 99.7%) and this affects things like electrical conductivity. With no brighteners, the gold would be 99.99% pure. It would also be softer but, since this isn't a wear area, like fingers or pins, that wouldn't cause any problems.


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## goldscraphobby (Apr 2, 2014)

I have to build a cell and setup a place for it. In the meantime I am going to put a smaller housing into dilute nitric and see what happens.
These are scrap housings from a "weather" satellite. I do not have the drawing specs they were either a Class 4 or 6. You are probably right and these will be the Class 4 and the smaller are the 6. 

We'll see.


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## pgms4me (Apr 7, 2014)

goldsilverpro said:


> goldscraphobby said:
> 
> 
> > . A couple of years ago, I visited a place that had several gaylords full of these exact same parts of various sizes, both the gold plated and the silver plated variety.



Goldsilverpro: Are the silver plated ones worth processing? and if so,what would be the best way?


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## etack (Apr 8, 2014)

pgms4me said:


> goldsilverpro said:
> 
> 
> > goldscraphobby said:
> ...



If they are silver over Al and you have quite a few of them then they would be easy to run. Just use nitric and be done with it. The Ag over Al wave guides came up a few years ago and Lou made a comment about the economic viability of it.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=14153&hilit=silver+waveguides

Eric


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## pgms4me (Apr 8, 2014)

Thanks for the reply Eric and the topic post too! Donn


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## goldsilverpro (Apr 8, 2014)

I agree with etack. Nitric.


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## goldscraphobby (Feb 11, 2015)

It worked!!
I had a small amount of old nitric and put one of the small housings in it in a small container and sat it on a shelf a few months back and forgot about it. I recently took it out and at first I didn't think it did anything but I looked closer and all the gold was mostly detached but still in the same form. Doesn't look like it did much to the housing.
So I peeled it off and that is what I got.
I just found some nitric and going to soak one of the big ones. The nitric is 70% so is a 1:1 with distilled water the best? Also is there any form of plastic that should not be used? I would be looking for something 4"x 12"x 14" with a lid.


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## g_axelsson (Feb 12, 2015)

goldscraphobby said:


> I just found some nitric and going to soak one of the big ones. The nitric is 70% so is a 1:1 with distilled water the best?


Great result!

You have the pieces so you tell us.

Break off some smaller pieces from a larger one and put into a series of different concentrations, put some loose lid on and check back regularly to see which one works and how fast.
I should suspect that the fastest one is 1:1 concentration but 1:10 would also work, just a lot slower. Then the question becomes how fast do you need to work and how much do you want to spend on acid.

To avoid dissolving some of the gold you should avoid water with chloride in it. Chlorides can be removed by adding silver nitrate solution until there is no white cloudy precipitation, then it is chloride free.

Let us know how it went.

Göran


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## bswartzwelder (Feb 12, 2015)

It has been said on the forum that you don't need distilled water for much of what we do. For final cleaning of gold it would be a good idea. Having said that, distilled water is well under a dollar a gallon at WalMart. Way cheaper than most anything else around. When the season rolls around, I buy 10 or more gallons of distilled water at the start on my recovery/refining season. It has other uses around the house and doesn't go bad.


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## g_axelsson (Feb 12, 2015)

Not everyone has Walmart around the corner. I'm lucky enough to have chloride free tap water. Not a hint of cloudiness when I dilute silver nitrate.

Göran


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## snail (Feb 12, 2015)

Don't foget water from dehumidifiers and air conditioner condensate, both are free sources of distilled water.
Dale


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## jason_recliner (Feb 12, 2015)

snail said:


> Don't foget water from dehumidifiers and air conditioner condensate, both are free sources of distilled water.
> Dale


I would suggest not. They're definitely free sources of mucky humid air condensate. But there's a lot more than H2O floating around in the air.
By extension, licking nightclub windows would be an acceptably suitable method of maintaining hydration. Personally, I will stick to my water filter jug.


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## goldscraphobby (Feb 22, 2015)

Even in this really cold weather the nitric is doing its job. 
Sorry for the reflections


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## GotTheBug (Feb 23, 2015)

Your reflection is ok, at least you didn't.....

http://www.jennyhow.com/wp-content/uploads/2007/09/naked-ebay.jpg


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## etack (Feb 23, 2015)

GotTheBug said:


> Your reflection is ok, at least you didn't.....
> 
> http://www.jennyhow.com/wp-content/uploads/2007/09/naked-ebay.jpg



Thanks for that!!!!!!!!!!!!!!!!!!

THat was great. I once was on the CL and was looking for a table and this amish made furniture ad had pics of there products the last pic was of the guy in his tighty whiteys. I contacted him and told him but everytime I hear there commercials on the radio I always laugh.

Eric


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## etack (Feb 23, 2015)

Au over Al is the best to process. nitric time and water.

Eric


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## goldscraphobby (Feb 28, 2015)

I got about 90% of the gold off the first one. Came off like peeling skin from a bad sunburn. nice and easy.
It needs some more cleaning and then refine it but right now I got about 6.9 grams
Thanks for all the help


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