Processing smelted SMDs

[kjavanb123]

All,

Previously I smelted a mix of SMD capacitors, resistors, Ta caps, Ru resistors. Dissolved the metallic parts in dilute nitric acid, here are some pictures and some interesting discoveries;

Starting materials, alloy from smelting mixture of SMDs, looks like copper alloy;


Two days in dilute nitric acid,


Undissolved metals in nitric even with heat, Ta Ru alloy?


Only part of it reacts with nitric at room temprature,


More pictures coming up.

Best regards,
Kevin

 

[Barren Realms 007]

You should have remelted this and made it into shot so your acid would be able to better react with the material. Your going to need more acid than what is in your beaker to do the job.

 

[kjavanb123]

I also tested nitric solution with stannous and it shows a weak sign of palladium.


Here is the filter paper trying to filter nitric solution, that dark brown color fine materials undissolvable in nitric passes the filter paper;


Kevin

 

[kurtak]

You should have remelted this and made it into shot so your acid would be able to better react with the material. Your going to need more acid than what is in your beaker to do the job.

correct - always re-melt your metal & pour it to shot

Also I would not trust that light lime green stannous test as a positive for palladium - palladium should start as a red/orange & shift to a dark (emerald) green even close to black unless the concentration is "very" low

some base metals will give you a light (lime) green stannous test - when you get a light green test like this you need to use DMG to confirm it is actually Pd

Kurt

 

[kjavanb123]

Kurt and barren;

Thanks for your advise. My first intention was to drill a sample from the alloy for fire assay and ICP tests, but then decided to dissolve them in dilute nitric acid.

I have to get DMG to run the test for palladium. But I dropped few ml of hcl to the green nitric solution and a layer of white color precipitated but stayed on top of the solution as you can see below,


I have not checked with this project yet to see it that white precipitant is silver chloride or not. Will post more results soon.

Regards
Kevin

 

[solar_plasma]

Hi Kevin,
did you check the chapter about fire assaying in Ammen's book and the chapter "FUSION OR CRUCIBLE PROCESS OF ASSAY." in Roserich's Metallurgy of gold.? I think there could be some good infos for your smelting projects (- though is it really smelting? If my understanding is correct, it is more of a fusion, while smelting is a redox process).

Good luck! I always enjoy reading your projects.

 

[samuel-a]

Kevin,

From a commercial point of view, IMHO there's very little chance you will make profit actually refining the resulting alloy from smelting SMD's.
It will contain mostly silver and Palladium (with trace amounts of Pt, Au and Ru) and you will be better served remelting the buttons into one homogeneous bar (when you have enough). Pull a sample for assay and ship it off to Metalor or JM.

If you insist on dealing with it, my approach would be:
remelt and granulate as Barren said (you may need to add a little copper/silver to get a more homogeneous melt)
Leach with hot dilute Nitric
Leach remaining solids with hot conc' Nitric ------------> precipitate silver as chloride and remove it
Leach remaining solids with hot AR (repeat if needed)
Conbine AR leach with previous nitric leaches
Bring pH to 1.5 with soda ash or bicarbonate
Cement PM's (mostly Pd) with zinc powder
Treat cemented powder as high grade Pd bearing material (>50% Pd)