processing MLCC's - grey sludge

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alvaschein

Active member
Joined
Feb 13, 2013
Messages
37
Location
Switzerland
Hi all
I collected more than 1 lb of MLCC's of different size coming from various boards.
Now I wanted to apply the method described by gold-n-scrap on a small sample of 10 g. I terminated the first step for remove the base metals, let the solution cool and settle over night. I poured off the purple solution. And now, that's the point why I'm asking: The method of scrap-n-gold says to syphon again leaving only the solids in the flask.
Now I'm insecure because I yes see solids (shiny metal) in the beaker but also a gray sludge. Does it come from the tin so that I can throw it away or what else could it be?

Thanks for any hint.

Roy

IMG_1527.jpg
IMG_1526.jpg
IMG_1528.jpg
 
alvaschein said:
Hi all
I collected more than 1 lb of MLCC's of different size coming from various boards.
Now I wanted to apply the method described by gold-n-scrap on a small sample of 10 g. I terminated the first step for remove the base metals, let the solution cool and settle over night. I poured off the purple solution. And now, that's the point why I'm asking: The method of scrap-n-gold says to syphon again leaving only the solids in the flask.
Now I'm insecure because I yes see solids (shiny metal) in the beaker but also a gray sludge. Does it come from the tin so that I can throw it away or what else could it be?

Thanks for any hint.

Roy

Keep all solids , only take of the liquid , If you follow the gold-n-scrap method then follow it carefully

also 10 gram will give if you are lucky and have the correct MLCC around 0,1 gram

scm
 
Probably a silver mirror due to the silver nitrate?

A lamp with a backplate of a cooler? looks like LGA775? and a candle; nice idea :)

Ps; they use dark glass containers to store silver nitrate because it will make a mirror due to light.

The dark purple substance looks like Pd and the grey-ish substance looks like SnO2 and probably some Ag(NO3)

If you haven't eliminated the base metals e:g Fe,Sn, etc then that will cement out the palladium followed by some silver.

Did you use HCl or HNO3 to eliminate the base metals?

if I recall correctly; Sam's method was to use HCl first and then HCl/clorox?

Then he dropped the Pd as a salt and refined it further from their.
 
The grey sludge on the bottom is solids, it probably is a lot of tin in it, but you could have a lot of precious metal powder mixed in with the tin oxides.

I see that candle "hotplate" as an accident to happen. The direct heat from a candle on the bottom of a glass vessel could easily fracture the glass. You need a heat spreader in some way. The other thing is that all that metal is going to rust as soon as you put any acids on it, eventually dropping small pieces of rust in your solutions. It will also cement out all your precious metals in case of a spill.

Nice palladium mirror, I got something similar when trying to cement PGM:s from an AR solution.

Göran

Edit : spelling
 
First thanks for all replies.

I followed the procedure of gold-n-scrap using HCl for dissolving the base metals. And now I'm stuck on the point of removing the liquid leaving the solids only. But there is also this grey sludge. Do I have to keep this sludge (considering it as solid) or can I throw it away?
The next step would be to dissolve all with diluted AR. Before I do so I want to be sure the first step (with the sludge) was correct for later apply the procedure on full scale (1 lb of MLCC).

Roy
 
If you had used enough HCl and it had enough time to react, there should not be any tin left in the solids. But I would expect a lot of fine powdered silver chloride, - don't forget this, after you have extracted the palladium.

But that's only a theoretical comment, my own 200g+ smd's are still waiting I get time for them.
 
The guide on Goldnscrap (from Sam) goes trough various leeching and participating to ensure all the base metals are gone.

Make sure you followed All of the steps in those guides.
 
Hi all

I have to say that Palladium recovery is a rather tough challenge!
This time I took a 50 g batch of MLCC's and followed really step-by-step the process described by gold-n-scrap.
I even kept the grey sludge. Well, I could reproduce all the solutions but in the final step of palladium and silver separation I was wondering what's going on.
I added Zinc until the stannous test was negative and let the solution settle over night. The next day I found everything looks similar to the pic on gold-n-scrap's website. But .... what is this again? Grey sludge (see pic)!
IMG_1532.jpg
Has anyone an idea what the heck this grey sludge is again? I encountered it also in the first step of removing the base metals (after cooling and settling).
I took a sample of this sludge and added conc. sulphuric acid --> no reaction. Another sample mixed with hydrochloric acid and hydrogen peroxide started to bubble and fizz producing a foam (see pic).
IMG_1536.jpg
I let the reaction terminate and the solution settle. A few hours later it was divided in a clear orange transparent top and a white (?) sludge on the bottom. I tested the solution and it seems there is plenty of Palladium (see pic).
IMG_1538.jpg
What could the white (orange?) sludge be (see pic)? How can I remove it?
IMG_1539.jpg

Just another question. Filtering the solutions I found a pink cloured sludge (not a joke!).
IMG_1534.jpg
I've never seen something like this! What could that be? Is it eventually a chemical compund of Cobalt?

Thanks in advance for all your replies!

Roy
 
Can you tell us exactly what steps you took in processing the MLCC's ?

that would really help in finding the cause.
 
This method is only for palladium recovery ...not for refining!



"You are now done with the Palladium recovery out of the Monolithic Ceramic Capacitors and prepared a Palladium Chloride solution ready to the Refining process."
 
9kuuby9 said:
Can you tell us exactly what steps you took in processing the MLCC's ?

that would really help in finding the cause.

The steps:
1. weighed batch of 50 g assorted MLCC's (dimensions +/- 0.8 x 0.8 x 2.0 mm)
2. put batch in beaker and added 320 ml HCl (that means 250 ml as 5 times the batch's weight plus 70 ml to compensate the difference of my 25% HCl to 32% HCl as described in the process)
3. let it boil for about 4-5 hours
4. let it settle over night
5. solution was divided into 3 sections (top down): purple solution (2" thick), grey sludge (0.5"-0.75" thick), metallic traces (visible only from the bottom view)
6. poured off only the purple solution, kept sludge and metals
7. added diluted aqua regia
8. let it boil for 3-4 hours
9. let it cool and settle over night
10. the solution was divided into two sections (top down): clear orange solution (2.5" thick), white(?) sludge (0.5" thick)
11. filtered solution
12. tested remainder for Ag --> negative --> to the waste
13. tested solution for Pd --> positive
14. added Zn to solution for cementing Pd

These were all the steps I took, ending up with this mysterious grey sludge...

Roy
 
alvaschein said:
9kuuby9 said:
Can you tell us exactly what steps you took in processing the MLCC's ?

that would really help in finding the cause.

The steps:
...
12. tested remainder for Ag --> negative --> to the waste
13. tested solution for Pd --> positive
14. added Zn to solution for cementing Pd

These were all the steps I took, ending up with this mysterious grey sludge...

Roy
No crushing?

Step 12, how could you test the remainder for silver, in AR all silver precipitate as silver chloride and with the action of light some is turned into metallic silver, giving a purple to gray tint. If this was mixed with other trash, oxides and left over ceramic then it could easily become a grey sludge.

I'm just in the middle of my first test of extracting silver and palladium from MLCC:s myself and I have extracted a lot of silver chloride.

Göran
 
g_axelsson said:
alvaschein said:
9kuuby9 said:
Can you tell us exactly what steps you took in processing the MLCC's ?

that would really help in finding the cause.

The steps:
...
12. tested remainder for Ag --> negative --> to the waste
13. tested solution for Pd --> positive
14. added Zn to solution for cementing Pd

These were all the steps I took, ending up with this mysterious grey sludge...

Roy
No crushing?

Step 12, how could you test the remainder for silver, in AR all silver precipitate as silver chloride and with the action of light some is turned into metallic silver, giving a purple to gray tint. If this was mixed with other trash, oxides and left over ceramic then it could easily become a grey sludge.

I'm just in the middle of my first test of extracting silver and palladium from MLCC:s myself and I have extracted a lot of silver chloride.

Göran
The easiest way to test for Ag is using diluted ammonium hydroxide to dissolve any assumed AgCl. AgCl reacts with ammonium to a complex called diamminesilver(I). After filtering again you receive a clear transparent solution. If there are any silver ions present you can test it adding simple table salt NaCl. If there is silver, silverchloride will precipitate again.

I washed a sample of this sludge to be sure the substance will react only with ammonia and then continued to the Ag-Test.

Roy
 
Then it is strange that you didn't find any silver at all.

Is this a mixed batch of MLCC:s or is it just one type?
My batch is all mixed up, collected over a year from mixed scrap.

Göran
 
g_axelsson said:
Then it is strange that you didn't find any silver at all.

Is this a mixed batch of MLCC:s or is it just one type?
My batch is all mixed up, collected over a year from mixed scrap.

Göran
It's a mixed batch. The colors vary from dark, brown, purple, white. I alway took care when removing them from the boards to check the Cxxx lables. They came away with solder. The solder has surely Sn and Pb in it, maybe traces of other metals like bismuth, ...

Now, what I did meanwhile is, I took the whole solution with the black (suppose Pd) and grey sludge (who knows what it is?) poured into an 18 mm testing tube and let it settle. I hope it will be easier to separate the grey sludge from the black Pd sediment. At least ist seems to work well as I have seen this morning.

Well, AgCl ... I think I have to think about it if I haven't made any error somewhere in the recovery steps.

Roy
 
I have just added a description of how I recover silver and palladium. http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=18564
at first I started writing a reply here but it got so long that I expanded it and put it in another thread instead.

I have just reread Sam's tutorial.
http://www.goldnscrap.com/index.php/others/62-recovering-palladium-and-silver-from-monolithic-ceramic-capacitors
He calls it palladium and silver recovering but never mentions where most of the silver ends up or how to get it out.

We all know (common knowledge on the forum) that a concentrated aqua regia solution can dissolve SOME AgCl but not much and diluted it holds very little. All other AgCl produced in the initial AR digestion is mixed in with the ceramics, oxides and other solids.
The second AR digestion would just redissolve the AgCl that came in the first batch and bring it along to the refining steps.

That is why I didn't follow his method when I processed my MLCC:s, I wanted to extract both the palladium and the silver.

When nitric leaches doesn't produce any more result I will do a final AR leach of my leftovers, just to make sure that I don't miss something like platinum and gold. Not that I think there is some in it, but beliefs are good, knowledge is better.

Göran
 
I think I'm getting crazy. I added to the orange solution (positive Pd test) zinc to cement the Pd. I received a black and grey sediment. Just for curiosity I added to a sample H2O2 - and all turned again to an orange turbid solution. No more black sediment!
As I know, Pd shouldn't react with H2O2! I think I'll take a breake of recovering Pd instead of having a constant battle with it!

Roy
 
Incinerate and wash and follow these steps

I first tend to use nitric 50/50 D. water to leach the base metals including Ag & Pd; after 2 or 3 leaches of fresh nitric solution; filter the solids out including the metastannic acid.

Drop out the Pd in the filtered nitrate solution with SMB or Coperras and; filter nitrate solution then recover the Ag with your preferred method.

Incinerate the solids including the metastannic acid; Then put the Incinerated solids in hot HCl; wash the solids a prepare boiling AR with a watchglass to leach Pt if it contains any.

After the recovery you can refine it or add it to your stock pot for later.

I hope this some how helps.
 
Maybe I found the error I made with the sludge.
The solution with the black/gray sludge was still acidic. Adding hydrogen peroxide, as a strong oxidator, it might have made the same effect with palladium as with copper and AP. Copper itself dosen't dissolve in HCl, but adding H2O2, it forms CuO which can be dissolved in HCl. So I guess it happened the same with Pd, as the most reactive element from the PMG's.
What I'm making now is cement Pd again, and wash it. So i get a ph-neutral situation. Phew, learning by doing and using plenty of brain...

I'll stay tuned...

Roy
 
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