# processing MLCC's - grey sludge



## alvaschein (May 18, 2013)

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


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## squarecoinman (May 18, 2013)

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?
> ...



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


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## 9kuuby9 (May 18, 2013)

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.


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## g_axelsson (May 18, 2013)

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


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## alvaschein (May 18, 2013)

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


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## solar_plasma (May 18, 2013)

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.


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## 9kuuby9 (May 20, 2013)

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.


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## alvaschein (Jun 5, 2013)

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)!


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).


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).


What could the white (orange?) sludge be (see pic)? How can I remove it?



Just another question. Filtering the solutions I found a pink cloured sludge (not a joke!).


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


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## 9kuuby9 (Jun 5, 2013)

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

that would really help in finding the cause.


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## rucito (Jun 6, 2013)

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."


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## alvaschein (Jun 6, 2013)

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


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## alvaschein (Jun 6, 2013)

rucito said:


> This method is only for palladium recovery ...not for refining!"



Yes, I know. At the moment I'm still in the step of recovering Pd. Refining will once a day be the next step.

Roy


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## g_axelsson (Jun 6, 2013)

alvaschein said:


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


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


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## alvaschein (Jun 6, 2013)

g_axelsson said:


> alvaschein said:
> 
> 
> > 9kuuby9 said:
> ...


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


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## g_axelsson (Jun 6, 2013)

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


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## alvaschein (Jun 6, 2013)

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.
> ...


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


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## g_axelsson (Jun 7, 2013)

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


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## alvaschein (Jun 8, 2013)

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


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## 9kuuby9 (Jun 8, 2013)

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.
> 
> ...



I hope this some how helps.


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## alvaschein (Jun 9, 2013)

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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## alvaschein (Jun 9, 2013)

I guess I got it!
I cemented as mentioned before, filtered and dryed the black sludge. After this I added HCl to remove eventually remaining Zn. And ... yes ... in my 18 mm diameter testing tube I have now an 8 mm thick black layer of undissolved black powder. I think this is now the Pd (?).

Roy


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## alvaschein (Jun 13, 2013)

Finally I got the Pd Black.
I took three very small sample and tried to dissolve them in hydrochloric acid, sulphuric acid and nitric acid. It only dissolved in nitric acid. The following test of this solution was Pd positive!

Well, yes, what a work. I have to go over the whole process again to see where is the most probable source of errors.

The yield was 0.2 g (mpfff, sorry had to hold my laughter). But anyway, it was fun.

Silver I didn't find, maybe I threw it away in the inicial steps, but plenty of metastannic acid - the ominous gray sludge that looked like jelly after having passed it through a centrifuge.

Roy


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## Marcel (Jun 14, 2013)

This may be a bit off topic but the MLCC leaching is not an optimal way. You simply have to redo it many many times to be sure that you have not left anything behind.
I took a very old beaker with dried-in remains from several leaches and thought: "Hey let´s give it another try!"
Added plain water(!) to the dried-in solids and let it stand for a month.
After that I received an canary orange solution Pd positive and precipitated another 1.2 g of Pd. As I said, these were old wrenched out solids from leaching! 
After that I took the dried remains added 1:1 borax and directly hit it with the torch.
At first there was noting spectacular happening, but under the scope I was able to see tiny silverish balls.
So I dissolved all in 5% sufuric acid, let it stand for some days and received a mass of tiny metal balls.
I put them under my torch again and out came 20g of Pd! ( I suppose mixed with some Au as well, but most must be Pd because I cannot even melt this button with my oxy torch.

I am telling this longwinded story just to say that leaching is not very effective - at least for me. I used hot HCl, dilute and 53% nitric, hot AP and what else to squeeze out the last drop of the 1 Kg MLCCs.
I think the problem is the decanting in this process. You never get all dissolved liquid out like that and you have to rinse with a lot of water.
Better try to use some funnel construction, where the liquid will leave downwards and you add water from top to wash the solids and the salts off. 
Before, I ran into this "Hey! What is this sludge?" as well. I is most likely silverchloride mixed with fine Pd powder and some other useless ceramic stuff. But it is the wrong approach to try to get this fine sediment from the bottom to the top. Instead wash it out downwards. Just my two cents.

Ok, this is not state of the art recovery. I should have dissolved and precipitated the sludge instead of going this straight way. But I did this before and I spend a lot of chemicals, water, time and energy to get my first 9gs, then I found more than 20g in this damned sludge!
Since I had treated the solids so many times, there were no base metals left anymore, so I gave this way a try.
Maybe there is even other PMs involded than Pd because this sponge nugget will not melt with my oxy torch. But at least I got them all!

Looking for a buyer for my nugget btw....


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## solar_plasma (Jun 15, 2013)

@Marcel

Very interesting post, Marcel! How much Pd did you get overall from 1kg?


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## Marcel (Jun 15, 2013)

29.68g unrefined Pd from 1.25 Kg MLCCs.


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## alvaschein (Jun 16, 2013)

Hi Marcel

Interesting post. But reading and re-reading I couldn't find the fil-rouge of your MLCC recovering process. It's not a critique but I would like to learn how the steps were (maybe others too).
When I was looking on my 0.2 g Pd out of 50 g MLCC's (yield 0.4%) I had to laugh considering the work I had to recover. Comparing to your 29.68 g Pd (yield 2.37%) I feel ashamed  .
No a few questions to you:
- Would you be so glad to post step by step how your recovering process was?
- Did you you use a batch of mixed or equal size MLCC's?
- Did you crush the MLCC's before processing them?

Thanks in advance

Roy


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## lysdexic (Oct 15, 2013)

Hi Marcel (Thank you one and all for this post, I'm sponging up information and trying to keep the cotton out of my ears and in my mouth)

I have been searching for info on the MLCC's and resisters and gathered tons of info on what to look for, but I'm only at a gathering and reading stage. I would like to ask something though and I HAVE NOT searched it. It's a safety question and not for my benefit so I hope it's okay. ...anyway:

Marcel was that red hot metal on a cement floor in the picture you posted? I'm sure it's common knowledge and the quantities are not large enough to make it a big risk but I feel I should share just in case anyone doesn't know and ends up in a sketchy situation. It's standard practice for those working with molten metals to work over a bed of sand. Concrete traps moisture and if the metal is hot enough or the charge of significant size it can vaporize the water which has no escape route so it makes one taking concrete with it. Even if there isn't enough heat for that to happen if working with any sizable charge of metal, crucible failure can be devastating. Sand is porous so explosion danger is minimized and splatter from crucible failure is also much less likely (and your metal will be easier to find).

Again sorry I hope everyone understands my reason.

Doug aka Dex


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## au-artifax (Feb 15, 2014)

alvaschein said:


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



? No filtering and rinsing after pouring off purple solution?! You still have waaay too much garbage in your mix to be throwing in the AR.


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## necromancer (May 20, 2014)

great posts, but i am still trying to figure it out, any help would be great

please reply here:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=20518&p=211572#p211572

thank you very much, i have another 2 KG to recover after i figure this out


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## saadat68 (Jun 5, 2018)

Hi I have 2 questions
In Sam's method we get all (or most) of silvers in precipitate in initial AR digestion
Can we refine silver with this process?
1- Wash all precipitate in first and second AR digestion with water
2- Add dilute sulfuric acid and some iron nails to precipitate and convert silver chloride to silver
3- incinerate them for rid of HCl and Cl and then digest them in nitric acid 
4- cement silver with copper 

----------------
In another method from goldrefiningwiki.com we have:


> Washing in hydrochloric acid to remove the tin. Prolonged treatment could dissolve the ceramics too, freeing the internal metal electrodes.
> Wash in water and then crush the ceramics to access the internal metal.
> Dissolve silver, nickel and palladium with nitric acid.


How much time needed for socking MLCCs in HCl to remove tin ?
(I want to remove tin without breaking ceramics with HCl and produce AgCl)


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## g_axelsson (Jun 6, 2018)

Just add acid and watch the reaction until it is finished. There is no fixed time, there are so many factors affecting the speed of a reaction. Heat, concentration, agitation, material, volumes.... who could tell.

Göran


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## saadat68 (Jun 7, 2018)

g_axelsson said:


> Just add acid and watch the reaction until it is finished. There is no fixed time, there are so many factors affecting the speed of a reaction. Heat, concentration, agitation, material, volumes.... who could tell.
> 
> Göran


Thanks
So one or two hours is enough.
Not several days
Right?
__________________
*
How much time and temperature needed for incineration to rid of HCl ?*


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## saadat68 (Jun 9, 2018)

saadat68 said:


> g_axelsson said:
> 
> 
> > Just add acid and watch the reaction until it is finished. There is no fixed time, there are so many factors affecting the speed of a reaction. Heat, concentration, agitation, material, volumes.... who could tell.
> ...



I test it 
I think maximum 5 hour is enough to remove tin without breaking mlccs


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## saadat68 (Jun 13, 2018)

Is palladium refining from MLCCs and chips dangerous like Pt ?
Do I must stay away from it ? Many of E-scraps have palladium!

If I drop palladium with DMG or cementation, Is it completely safe ? Even in chloride solution ?


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## Raza shahid (Sep 15, 2018)

Hi gyz i am new here i am tryng to get pd salt from mlcc and follow gold n scarpe tutotial when i precipitate black pgm by putting zn or Al, but when i sm tryng to disolve tht pgm black powder in aquaregia it did not dissolve completely i heated 2 hours but blck powder still un disolve, any one can help me please, discribe the right way to dissolve


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