Cheap & Easy Deplating... Now What?

[Anonymous]

While in college I used to work as a Lab Assistant in a Water & Soil Analytical lab.
The chemist there showed me a neat trick and I was able to replicate most of it at home, but now I'm stuck.
Let me explain what's been done and maybe someone can help me figure out what would be next.

To start with you need the following ingredients.

#1 non-iodized table salt, preferably without any whiteners, the point is to get it as close to straight NaCL as possible.
#2 1 cup or bowl, the shallower the better must be glass ceramic or plastic, (no metal!).
#3 A cheaply available power supply, typical walwart seems to be just fine. The one I choose was a 12v 750ma Negative Ground from an old cable modem that had long since died.
#4 Fresh coffee filters, the cheap kind, I get mine on buy one get one 200 for $1 specials.
#5 2 Alligator Clips (not strictly necessary but very nice to have)
#6 1 or more pieces of junk, gold plated jewelry.
#7 Hot Tap water.

Take the power supply, snip the end connector off. Strip the wires about 1/2inch or so and attach them to the alligator clips. The wire with the dotted line is typically the positive. By convention I attach the red clip to the positive & the black clip to the negative when I have colored clips.

Next take the cup and fill it 3/4s of the way up with hot tap water (distilled might work here too, but tap seems to be just fine).
Take a 1/4 tsp of the table salt and dissolve it in the water stirring until there is no more salt visible.
Take the items to be de-plated and attach them to the alligator clips, then attach the alligator clips to the cup, so that the item to be deplated is in the water as far as it can go, but do not let your clips touch the water directly (Otherwise they corrode badly and it can foul the solution).

Take the whole thing to a well ventilated area.

Now plug the transformer into the wall.
Within a few seconds you should see one side start bubbling.
Add salt water 1/4 tsp at a time to a max of 1TSP total in solution.

I believe, the bubbles you see are Hydrogen Gas.
The other side will periodically "smoke" thats probably chlorine gas.
Depending on the size of your item and the thickness of the plating your item should loose all or most of it's gold plate in 15 mins to an hour.
As soon as the majority of the plating is gone we want to pull the item out to avoid fouling the solution with unnecessary junk from the pot-metal underlaying the item.
Don't get greedy, pull the item out once about 3/4s of the plating is off, and just scrap the remainder off with a small xacto knife, it should come pretty easily at this point.

Next simply get out your coffee filters place them in a clean cup and dump your solution slowly into the filters.
What you should have now is highly oxidized metal sludge (I believe it's gold chloride but I'm not sure), along with a mix of junk metals that came off if one side deplated too quickly. The gold should be in the filters and it will look like a mud or sludge. Mine had several distinct colors of mud.
Brown, Green, Yellow, Blue & White.

I think the mud was the following
white (salt).
Blue/Green (silver/copper)
Brown, Gold or possibly iron (The item I deplated was responsive to a magnet so I assume some ferrous metal was in it)

Ok so thats what I have and I'm not sure what to do next.

Here is how I believe the process is working, based on having run the experiment about a dozen times over the past few weeks.
Applying electricity to the brine (saltwater solution), appears to produce the following items in various quantities...
Chlorine Gas
Hydrogen Gas
Sodium Hydroxide (Lye)
Hydrochloric Acid (HCl)

The Chlorine Gas is being formed at one side. Chlorine gas is highly corrosive which is why the item clipped on that side deplates dramatically faster than the item at the other side (which is still deplating, just much slower).

If you leave the item on the quiet side in too long, white crystals start to develop on the item (this may just be because of the pot metal), those white crystals appear to be Sodium Hydroxide. Also the water has a soapy feeling which I believe is more Sodium Hydroxide still in solution. I get this information because applying current to brine is how they make Lye now days and is a process called the Chloro-Alkali process I think. Also the fingers I used to test the consistency of the water now appear to be missing a small patch of skin (Whatever is in the water it's really, really caustic to skin and doesn't wash off very easily)

I believe the Lye in water solution is responsible for the deplating action I am seeing at the other side.

Anyways now I have a nice thick mud sitting in a coffee filter & drying in my home made dessicator.
I know there is gold at least some gold in that mud & I suspect that the mud is gold chloride, but I don't know how to verify this.
I'm thinking I may just get a blowtorch & a crucible & burn/melt it to see what comes of it, but before I do I wanted some advice on other steps I ought to take to clean this up, I'm really not interested in killing myself with toxic fumes or an explosion or something.

Also the water I filtered out has a very odd color too. It's a Yellow/Green color & I wonder if there isn't gold or something still in solution there.

Please note: I'm aware of AR process but what I'm trying to do is come up with a way of processing this with common household chemicals & unfortunately Nitric Acid isn't readily available in my house or at the local grocery store, not much luck with HCl here either.

Thanks in advance for the feedback, thoughts & comments are appreciated & before anyone mentions it, I'm now using gloves & googles to prevent losing more skin

 

[butcher]

stannous chloride to test for gold in chloride solution, but if base metals as powders you probably will not have any gold in solution, the color of solutions with base metals are not a good sign of gold in solution.
Inceneration will help to oxidize the base metals and help prepare your powders.

do not just melt powders, eliminate the base metals first. nitric can easily be made, it would be the best for this.

a boil in HCl will eliminate some base metals,

also HCl/ H2O2, Acid Peroxide, it will do a fair job of ridding most base metal, but is slow and can still leave some copper (I) chloride, lead chloride and silver chloride if present, lead chloride slightly soluble in boiling hot water, silver chloride is not, and you need settling time for fine powders, a double boiler helps here, or plate warmer to keep water hot while fine silver powder settles,

silver if any can be removed with ammonium hydroxide (household ammonia), but it takes an awful lot of it for small amounts of silver, you can precipitate the silver from it with HCl, as silver chloride (Which needs conversion before melt), but Never let the ammonia/silver complex dry it can be an explosive mixture heat and shock sensitive DANGEROUS, always acidify the solution first, with HCL it will also form ammonium chloride which we can use. this step I probably would not use too much trouble and you may have no silver any way,and you can also leave most of it behind as powder in the next step.

HCL/Bleach will dissolve your gold powders and leave the insoluble chlorides like silver behind, if your gold powders were fairly pure you would have a very yellow solution if impure they will tend more dirty green and may not filter worth a darn,(inceneration can improve this),
if solution was clear yellow gold can be precipitated from it, (eliminating excess chlorine nessary before using your chemical to precipitate gold) but if green and dirty I would use copper buss bar to recover, refining the gold powders will also needed.

here again you will need to make stannous chloride for testing your solutions
nitric is easy to make and plenty of information here on the forum about it.

save up jars full of powders, read up on the forum, learn to make the chemicals you need like stannous chloride, nitric and so on, learn the different ways to recover your gold, once you get some of this under your belt then attack them jars full of your powders.

there are several different ways to recover gold from powders, but understanding principles helps, these principles are gained from reading the forum and HOKE's book.

You may find Laser Steves concentrated nitric cell better solution for processing the plated stuff you are doing, see his web site it will give you an armload of information, and probably eliminate alot of your questions, he covers most of it.

 

[texan]

You may find Laser Steves concentrated nitric cell better solution for processing the plated stuff you are doing, see his web site it will give you an armload of information, and probably eliminate alot of your questions, he covers most of it.[/quote]


Unless Steve has come up with a new cell I think that should be a concentrated "sulphuric acid" cell instead of a nitric cell.

And I am game to try this at least once.

Texan

 

[butcher]

Good thanks, Texan. my typo
sulfuric is correct
guess I have nitric on the brain.