Electrochemistry My Copper Cell Parting Silver

[rusty]

Over the summer months I saved the silver soldered joints and elbows from decommissioned AC's and other types of refrigeration equipment.

When I eventually got around to melting all this material into anodes, thought what the heck copper is a good collector of precious metals then decided to add some milled IC's into my last two melts. Which turned out to be a big mistake.

The IC;s came from those telcomm boards I was working on just before we made the move from Birnie over to Elphinstone, apparently there was some gold in them chips after all.

This particular anode has been in the cell for over a week with very little degrading of the anode, obviously not enough copper to plate out onto the cathode.

The other anodes with only copper and the silver soldered joints are plating out very nicely in a timely manor. I'm quit satisfied with how the cell is working away.

I'm running three cells simultaneously from my Kocour rectifier

I've played around with different anode /cathode configurations,

One anode / one cathode facing each other, then one anode center of the cell with two cathodes on the outside facing the anode from either side..

Now I'm using a pair of anodes fixed to the outer edge of the cell with one cathode set center, each anode plates out from the side facing the cathode and this is the set up I have settled on to use.

I must find a mold that will allow me to cast square anodes, the round ones work alright but require to much baby sitting. If you look at the anode in the picture you will notice that they tend to erode fastest near the top level of the electrolyte.

Both pictures are of the same anode at different stages.

 

[skippy]

Interesting Rusty, is there some sort of film developing over top of the anode? There must be something blocking the flow of current, otherwise I would think the anode should dissolve, as long as the electrolyte was conductive and acidic.

 

[goldsilverpro]

Gill,

What's the weight of the anode?

What is your guess as to the metals - mainly Pb, Sn, Cu, Ag, I assume - and their percentages in the anode?

What is your electrolyte solution - H2SO4, HNO3, HCl, etc. - and its strength?

 

[rusty]

Gill,

What's the weight of the anode?

What is your guess as to the metals - mainly Pb, Sn, Cu, Ag, I assume - and their percentages in the anode?

What is your electrolyte solution - H2SO4, HNO3, HCl, etc. - and its strength?

My electrolyte contains 240 grams copper sulphate per liter of water with 75g H2S04 liter, a recipe taken from Ammens book 2nd ed page 202. or page 166 from his 1rst edition.

About this time last year I was working on those telcomm boards, I had depopulated the boards, incinerated the chips then removed anything a magnet would pick out before doing a nitric leach. Then my life came to a grinding halt with this unexpected move.

Next the copper elbows and other silver soldered connections from decommissioned refrigeration equipment come into the picture, Last month melted these into anodes to part the silver from the copper. After pouring 4 anodes spotted the bucket left over and untouched since the move added the contents into the crucible along with the copper / silver mixture.

All the other anodes are performing beautifully.

It's unfortunate that I did not weigh this problem anode before It entered the cell, it has spent 10 days in the cell and still weighs 1 3/4 lbs, the color is that of 10k gold.

After I poured the original anode you could certainly see a gold color on the bottom side, after the anode had been in the cell for a couple of days, switched it over to the other side of the cell replacing the cathode with a fresh side now exposed to the cathode.

Also I want to add that during that 10 days in the cell quit a bit of copper has also dragged down to settle with the slimes.

Sorry I could not be more help in determining the makeup of this anode.

The anode is not heavy enough to be a solid piece of 10K gold, so we're being realistic about this adventure in backyard electro-chemistry.

Later in the day I will take some drill shavings, then go to nitric to see if any solids stay behind. I will post my results.

 

[rusty]

Results from drill shavings, drill hole shows the color is persistent, drill shavings 0.7 grams into dilute nitric left behind some insolubles which I have now dissolved into AR. As soon as I find my stannous will test this for gold, DMG for palladium.

Now for the big surprise, the last test tube is the solution I decanted from the nitric acid, added some table salt the grains are rice from the shaker, after no reaction to be sure a bit of HCL- no silver chloride. Most ask where has my gold gone, I'm sitting here wondering where my silver went.

It's my best guess that this anode is cast entirely from the IC chip residues left over from before the move, and that the green is iron. This would account for the missing silver.

If the little bit of solids left behind were in fact gold, how much gold does it take to give an alloy a distinctive gold coloring.

Wish I had an analytical scale sensitive enough to weigh up the solids before and after.

 

[butcher]

I am a bit confused as to what all is going on here. I t is hard for me to follow what was done and what is not working.
Sounds as you have an unknown metal that may contain value.

I would take a larger drill and drill out several holes saving shavings.
Get enough shavings to gain some weight, weigh shavings, dissolve in nitric acid, decant rinse (this solution tested for silver, and palladium, possible PGM if silver content was very high (not likely from what I gather).
(You could also cement this on copper, rinse, melt to bead and weigh)

The insoluble portion could be dissolved in aqua regia, tested in solution and values precipitated, washed and button melted and weighed.

You may have an alloy that in the electrolyte is passivating, and will not go into solution, if so changing electrolyte to another acid may help.

You could have an alloy very hard for acids to attack (metal passivating) or alloy resistant to solution.

You may find you need to in quarter the anode to lower the metal that is resistant to electricity or acid.

Beside the acid approach may try to saw off several pieces and experiment in different cells with different electrolytes.

 

[rusty]

Recovered 3 1/2 lbs of silver from 4 / 20 liter pails of silver soldered refrigeration and air conditioner connections removed from condensers and evaporators & misc. other connections.

My advice is check your sources to see if they were soldered with tin or silver solder, run your anode as close to 96% copper as possible otherwise your going to loose copper ions from the electrolyte last run your voltage fairly low otherwise your going to deposit unwanted values onto the cathode.

The 4 pails weighed in the neighborhood of 75 lbs, just over 30 days to refine the copper my silver still has to go into the silver cell.

I did purchase a half pail of joints from four large roof top evaporators which did not cost very much even at $4.00 a lb as the copper tubing is very thin with hardly any weight. And there was plenty of solder gobbed on, so I think that I got my moneys worth.

 

[samuel-a]

Rusty, could you post a picture of said connections ?

 

[rusty]

Rusty, could you post a picture of said connections ?

From any air conditioner unit you have a pair of aluminum finned rads a copper tube has been bent with an elbow on one end the other end has a soldered elbow. You can not miss them, what I found out the hard way is the newer air conditioning units used tin solder.

I do not have any joints or elbows to show a picture of, they all got melted into anodes.

 

[samuel-a]

I do not have any joints or elbows to show a picture of, they all got melted into anodes.

Thanks, your description is enough.

Guess i should have in my pocket a vial of Schwerter's solution whenever i'm in yards...

 

[rusty]

I do not have any joints or elbows to show a picture of, they all got melted into anodes.

Thanks, your description is enough.

Guess i should have in my pocket a vial of Schwerter's solution whenever i'm in yards...

Yea you can bet that I'll best testing with Schwerter's before dismantling in the future.

The copper cell was easy to run it held 4 gallons of electrolyte which I topped up once a day.

Big city yards already know about the silver, they would not sell to me maybe you'll have better luck.

 

[rusty]

Almost ready to melt my silver into anodes,

The first picture, stainless steel pot filled with petrobond sand firmly packed around the stick, once removed will leave a cavity which measures 1 1/3" x 3/4 inches to receive the molten silver.

If I had made more than one stick pattern I could have made better use of the petrobond.

Second picture crucible tongs I threw together late this afternoon.

Third picture miniature titanium basket with anode bag.

 

[lazersteve]

Looking nice Gill,

Can't wait to see some live action shots!

Steve

 

[rusty]

The big melt.

 

[Patrick_R]

Just one minor concern. That propane tank, Empty or in use for your furnace? Just my opinion, you might want to move it back a wee bit from such a flame.

On another note. Can you please post the specs on your ceramic wool/blanket (or PM to me).

Thanks

Comrade

 

[rusty]

Just one minor concern. That propane tank, Empty or in use for your furnace? Just my opinion, you might want to move it back a wee bit from such a flame.

On another note. Can you please post the specs on your ceramic wool/blanket (or PM to me).

Thanks

Comrade

The ceramic blanket was salvaged from a big gas fired hot water boiler that I hauled in for scrap.

The 800,000 btu torch is supplied with fuel from a 500 gallon propane tank, that small tank would be empty in less than 3 minutes or frozen.

 

[butcher]

I like the quickie furnace, it looks camouflaged in the snow.