Monolithic capacitor refining

[kjavanb123]

All,

I hope this is in the right part of the forum. So I collected all the tiny MCs from the boards I have mentioned in my previous email "first time with e-scrap".

Total weight is 3.22 grams of MCs. I put them in and dropped in enough HCL to cover it and boiled it, first it went dark purple then went to yellow and it dark brown as you might be able to see from the pics below.
I then I poured water to it's twice the volume, let it settle, and siphon some of the remaining. Then I added 2 parts HCL, heat and added 1 part H2O2 and dropped nitric in small increments. Its boiling as we speak.

Just tested and showed no signs of Pd in it, so I am hoping it has some Ag.

Tommorow I will go after fingers.

Here are the pictures.

1. 15 mins into addition of HCL to monolithic capacitors


2. After half and hr boiling in HCL


3. After an hour 10 mins of boiling in HCL


4. After water addition and settling.


5. Boiling the residue from picture 4 in AP and nitric


Stay tune for more pictures.

Peace
Kj

 

[jimdoc]

I know you are in "test phase", but I would save up some more weight for testing or processing as you will see very little values from 3.22 grams of monoliths. Not all have palladium, and if they do it is said to be around 1-2% of weight at most.

Jim

 

[kjavanb123]

Jim,

Thanks for your respond. I know it's pretty small sample to work with. and it has not shown any sign of Pd in the solution as of yet. I was hoping to measure the silver if there is any.

Also, the solution that contains Tin/Nickel in the first part of processing, when dissolving base metals in HCL, can it be recovered using eletrolysis? Seems to me that most of the MC content gotta be the base metals.

Best regards,
Kevin

 

[samuel-a]

Afer your treatment, any silver is most likely in form of chloride mixed with the white silt from the ceramics.

Did all of the ceramics disintegrate to fine powder?

 

[kjavanb123]

Samuel,

Here is what the MCs and AR solution after being boiled for 2 hrs look like. You mentioned any possible Ag should be in the white powder at the bottom of beaker or is it in AR solution?



i haven't seen the MCs at the bottom of the beaker yet. But I presume they have been dissolved.

Kevin

 

[samuel-a]

Silver chloride is a white soild in presence of acid.
Its solubility is extremely low.

So, yes, it is mix at the bottom with other materials.
Iv'e assayed mlcc's with more then 10% (by mass) Ag in them.

 

[kjavanb123]

Samuel,

Thanks for your info. Now I am gonna filter it, test the solution for possible Pd which I doubt it will be any. Then dry the white powder, should i dissolve it in hcl and then put a copper rod to get the silver?

Best regards,
Kevin

 

[nickvc]

Kevin even if you have any silver in your sludge it will be a very small amount and will be silver chloride which will not dissolve in HCl. If you really are intent on recovering this I'd suggested drying the powder then incinerate it wash with hot HCl rinse and then use zinc to convert it it back to silver metal. For the amount involved I wouldn't bother and whatever you do recover won't be pure silver so will need further refining.

 

[samuel-a]

For experimental sake:

Once you dry the solids, cover it with NH4OH (ammonium solution) and stir vigorously for couple of minutes. Let it sit for an hour or two and seperate the solution from the solids.
Add few drops of HCl to the solution, if a white cloude (AgCl) forms, it is reletevly pure silver chloride.


Do a search here on the forum on Silver and Silver chloride to gain a more solid grasp regarding silver's chemisty. It's all here.
good luck.

 

[kjavanb123]

Samuel,

Per your instruction, after I dried the grayish residue from MCs dissolving in AR and peroxide, the total weight for the dry weight is 6.99 grams. I covered it with ammonia 28% and shaked the beaker till pretty much everything except the plastic covers for monolithic capacitors dissolved. Let it settle for 2 hrs, filtered the yellowish solution, and added HCL, white clouds formed, which i am guessing it's from the ammonia, as i used to see the same cloud when purifying Pd salts.
After some additions, I could see some blackish precipitant formed at the bottom of breaker, however the color of solution didn't change much. Do i need to add more HCL till there is color change in solution? Are these tiny black pieces are AgCl? Here is the picture show, and i appericate your comments.

Dried residue from MCs dissolving in AR


Addition of ammonia to the dried residue


Solution after 2 hrs.


Filtered solution after addition of HCL


More HCL added and black particles formed. AgCl??


Regards,
Kevin

 

[niteliteone]

Per Samual-a's instructions

For experimental sake:

Once you dry the solids, cover it with NH4OH (ammonium solution) and stir vigorously for couple of minutes. Let it sit for an hour or two and seperate the solution from the solids.
Add few drops of HCl to the solution, if a white cloude (AgCl) forms, it is reletevly pure silver chloride.


Do a search here on the forum on Silver and Silver chloride to gain a more solid grasp regarding silver's chemisty. It's all here.
good luck.

 

[samuel-a]

Hi Kev

The color is not what i had expected, seems like there was left over Pd salt in the ceramic silt that causes that color.


I guess i should have thought about it before and haven't been clear enough... when you add HCl to ammino silver complex (and excess NH3) two things will be noticeable.
A white cloud of NH4Cl (g) will from above the solution as the HCl gas react with NH3 gas.
Second, in the solution, the Ag ammino complex brakes down to form once again AgCl, which also give a cloudiness appearance to the solution.

From your phote, it does indeed seems like AgCl had precipitated.

Acidify the remeining (orange) solution and test with SnCl2, if positive for Pd, add to your stockpot.

 

[kjavanb123]

Samuel,

Thanks for clearing it out. Here is what the black powder and white crystal that have grown over night in solution.



Now, Hoke's suggest to digest the silver chloride in sulfuric acid and drop the silver metal with zinc powder. I was on impression that silver chlroide are white powder, I have black powder and white crystal, which i am not sure what they are.

As for Pd in solution, stannous didn't show any trace in it, so I just dumped the solution in a different jar for further refining.

Best regards
Kevin

 

[samuel-a]

AgCl is white but light sensitive... it will darken on exposure...
Though i'm not so sure that is the case here, i'm at a loss regarding to what is your black powder.

The cementation process you mentioned is easy enough, Steve has a video on that. then you could potentially re-refine that silver.


p.s. - the color of AgCl very much depends on the solution of which it was dropped out of... As the crystals forms, they tends to trap and lock (physically, not chemically) some of the solution.
I once precipitated AgCl from a nitrate solution of 50/50% Ag/Pd (w/w), even after 10 boilings in water the AgCl remained pink (ish).