# Silver Cell Slimes - How Do I Seperate Palladium and Gold



## kadriver (Nov 11, 2011)

I have a 400 ml beaker sitting in my shop that contains material from a silver cell anode basket from a month or so ago.

I added some nitric acid and let it sit. I turned a dark brown color that looks like coffee. From past posts I believe that this solution contains palladium.

I have some DMG ordered but it has not arrived yet. 

There may be some gold in there also, but I have no clue where to start (except to add nitric acid).

Could someone point me in the right direction - Thank You.

kadriver


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## philddreamer (Nov 11, 2011)

As I understand, the proper way would be to rinse the sludge, incinerate;
then run thru nitric to separate the Pd, then the left over sediment thru AR.
Then precipitate the gold, & test for any PGM's.

I went straight to AR, though, & precipitated the gold; solution tested + for PGM's w/stannous, so I added it to my stockpot for later recovery.

Phil


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## kadriver (Nov 11, 2011)

If I add nitric acid first, then that should dissolve any silver that is in there. Would the palladium, if any, also dissolve with the nitric acid?

Once the acid has dissolved the silver and palladium, then I would filter out the remaining solids and cement the filtered liquid to get the silver and palladium.

Then add AR tot the solids to dissolve gold, filter and drop with SMB. Does this sound correct? 

Thanks - kadriver


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## philddreamer (Nov 12, 2011)

"If I add nitric acid first, then that should dissolve any silver that is in there. Would the palladium, if any, also dissolve with the nitric acid?"

Yes, palladium dissolves in nitric.

"Once the acid has dissolved the silver and palladium, then I would filter out the remaining solids and cement the filtered liquid to get the silver and palladium.
Then add AR tot the solids to dissolve gold, filter and drop with SMB. Does this sound correct?"

Yes; at least, that would be the way I would do it. 

After precipitating the gold, don't forget to stannous test for PGM's that didn't dissolve in the nitric and are part of the sediment.

Phil


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## Harold_V (Nov 12, 2011)

kadriver said:


> If I add nitric acid first, then that should dissolve any silver that is in there. Would the palladium, if any, also dissolve with the nitric acid?


That's the precise procedure. Here's a couple things that will help guide you to success. 

Use only the amount of nitric that is necessary to dissolve the silver and palladium. Any excess will have to be evaporated in order to recover the palladium. Leaving behind a trace of both silver and palladium may be in your best interest, so you ensure you've not overdone it with nitric. Nothing will be lost---you'll just recycle everything for recovery at a later date. 

When you have concluded the nitric digest, allow the solution to settle well. No need to filter unless you wish to. Separate the solution from the solids (they will contain gold and platinum if there's any present, plus possible traces of silver and palladium). Rinse the solids with distilled water and repeat the separation. Combine the rinse solution with the solution first extracted. 

At this point, it's important that you separate the two elements. Otherwise you'll send all of the palladium back to your silver cell, complicating the parting of silver. To do that, introduce HCl to the separated solution. That will precipitate silver as silver chloride. Add HCl until you no longer get a precipitation of silver chloride. Allow to settle, then separate the silver chloride from the solution. Wash the silver chloride well, several times, to extract as much of the palladium as you can. You can use tap water with no issues (remember, you're dealing with a chloride solution now). 

Evaporate the resulting solution, to a very dark (black) brown solution, heavily concentrated. Filter, then recover the palladium with ammonium chloride and sodium chlorate. That is done heated. See Hoke for instructions on the recovery of palladium. 

Convert the silver chloride to metallic silver using one of the commonly accepted methods that involve the use of other metals. That way you recover traces of palladium that remain in the silver chloride. I used aluminum, but only because I had it. You can use scrap steel. Note that you should not allow a lot of palladium to return to the cell, as it complicates the parting process (as you discovered). 

You can process the remaining solids by dissolution in AR, or the solvent of your choosing. Expect traces of silver chloride to form. You likely will find traces of palladium, along with gold. Platinum, too, if you've handled any. Selectively precipitate the gold. The traces of palladium may not respond to recovery. You may wish to add that solution to the first extracted palladium solution, to minimize how much you recycle. Traces that are not recovered (after extracting the palladium) should be sent to the stock pot for future recovery. Do NOT expect a full recovery of platinum and/or palladium. They don't cooperate. You will always have traces left in solution---which are sent to the stock pot. 

Simple, eh?

Make sense? 

If not, lets talk. 

Harold


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## philddreamer (Nov 12, 2011)

Thank you Harold!

Phil


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## kadriver (Nov 12, 2011)

Harold & phil:

I have printed a copy of your posts and I will take them with me to my shop. There I will carfully study them and apply the process outlined.

Plus I will read about palladium recovery in Hoke. I don't have ammonium chloride or sodium chlorate (I guess I had better order some of each).

But I do have aluminum powder. The process for using it is not described in this post, maybe in Hoke - I will check.

It seems pretty straight forward and I think I have a grasp on what to do.

There is lots of brown mud left in the bottom of the 400 ml beaker that has already been processed with nitric about a month ago.

And there is about 1/4 inch deep black solids in the bottom of the container holding the latest silver cell slimes.

Since I have never done this before, I have no idea on what to expect from these two containers of silver cell slimes.

Thank you - kadriver


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## kadriver (Nov 12, 2011)

philddreamer said:


> As I understand, the proper way would be to rinse the sludge, incinerate;
> then run thru nitric to separate the Pd, then the left over sediment thru AR.
> Then precipitate the gold, & test for any PGM's.
> 
> ...



Is this part of the process? I do not remember seeing the incineration part anywhere except here.

kadriver


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## philddreamer (Nov 12, 2011)

Harold recommends to incinerate because it helps get rid of substances that sometimes won't allow the sediment to dissolve properly. For example, if you're running the sediment thru nitric, incinerating will get rid of any HCl present, (or any other chemical), that could give you some results that you don't want, & so on.

You can skip incinerating; for sediments like these, I ussually skip the incineration. 

Harold's detailed steps are excellent to have & follow. 

Phil

P.S. While reading today, I found this post, I hope it sheds more light:
"Re: metajunkfite or green
The steel can, to incinerate in, is a bad Idea.

"rinse and incinerate (i use a tuna can that has no lip) on your hot plate. if you use a metal can be sure to burn it first and wash using steel wool. "

Unless you intend to dissolve the steel can you will loose values, and even dissolving the steel would be a bad idea.

Your values would plate out onto steel and gold can be lost,

Use stainless steel your corrosion of it would be less, attack of steel would be less and gold loss minimized.

Also if you are incinerating a chloride powder (metals dissolved using Hydrochloric as an ingredient), these salts can be acidic, neutralizing them with sodium hydroxide (NaOH), and rinsing well with water before incineration, helps in two ways,

it helps to remove the acidic component (these acidic salts actually becomes more acidic as the heating of incineration progresses) and it converts chloride powders to oxides and hydroxides of these metals, 

And rinsing well also helps to remove the salt water we formed from the chloride salts and the sodium hydroxide, 

As heating gold chloride or salt in an incineration process can make some of the gold volatile and escape in the smoke formed in the incineration process as HCL or chlorine gas formed escapes. 

Also starting with low heat at the beginning of the incineration process is a good idea, it helps to drive off water (or chemically combined water) and the volatile gasses that form from the heat (made from our acids or salts), helping to remove them from powders minimizing value loss in smoke, helps to dry these powders and minimizes bubbling as splashing another way to loose values, once these salts fuse then I bring up the temperature until the powders glow red hot, keep them red hot crushing any clumps stirring and getting as much air or oxygen exposure as possible.

I hope this is understandable as after working all day, I may be too tired to be posting my rambling thoughts.
Butcher"


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## Harold_V (Nov 13, 2011)

To be clear, I didn't incinerate the slimes from my silver cell. They were recovered from material that was melted immediately before being introduced to the silver cell for parting, so there was nothing of which I was aware that would need to be eliminated. The slimes come from a nitrate solution, so considering nitric is the acid used for the next operation, there is no real need to incinerate (pretty strong words from a guy that insists everything needs to be incinerated, eh?  ).

A note of interest. Slimes from silver cells are often processed in concentrated sulfuric acid by boiling in an iron kettle. Concentrated sulfuric does not dissolve iron, but it's obvious one must keep water out of the process. In such a case, well washed and dried slimes would most likely be required. I have no experience with that process, which likely has distinct advantages, one of which is to eliminate the finely divided silver that comprises the vast majority of the slimes. 

The process I outlined is the one I used----although it may not be the best possible choice. What I can guarantee is _that it works!_ Study and keep an open mind, for there may be a much better process at your disposal. 

Harold


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## kadriver (Jan 2, 2012)

I dissolve 925 & sterling silver (some gold plated) in dilute nitric acid over heat to produce silver nitrate for cementing the silver to make anode bars used in my silver cells.

I filter the resulting silver nitrate solution into a vacuum filter flask using a buchner funnel and medium filter paper.

I rinse the filter, and all the solids it containes, with lots of distilled water and just leave it in the buchner funnel to dry.

Once the filter paper and all the solids are dry, I carefully transfer the filter to a bag designated for these type filters only.

Since I lacked knowlege on how to process these filters, I just let them accumulate. 

I now have about 50 or more filters full of unknown material (some visible gold foils) - all from dissolving 925 & sterling silver with nitric acid.

I got the bag out and looked through it the other day and found this filter (see photo) loaded with gold.

Other than having to deal with the paper, I am planning to treat these filter paper wastes with the same process used to treat silver cell slimes.

But before I start, I have a couple of questions:

1) is this the right way to go, using silver cell slimes treatment to process these silver nitrate filters?

2) If yes, then can I just add the whole load, filter papers and all, to a nitric acid bath in a large beaker?

3) should I incinerate the filter papers first, then proceed with the silver cell wastes treatment (on the filter paper wastes)?

Thank you - kadriver


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## samuel-a (Jan 2, 2012)

Inciniration will serve you best in my opinion.
Remember that the filters will light up easily due to remnants of nitrates, so watch out for that.
Make sure everything is ashed and no carbon left (duh... 8) )

Other then that, a nitric leach is only natural to follow inciniration.
Later AR.


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## HowitzerMan (Mar 5, 2013)

Greetings! I just wanted to say how nice it must be to forget all about a filter paper full of gold :shock:


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## amesametrita (Mar 5, 2013)

Straight to HNO3 = loose platinum


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## kadriver (Mar 5, 2013)

amesametrita said:


> Diluted H2SO4 1:4 (water:acid) dissolves silver but not palladium.
> And platinum doesn't go with silver like it goes in HNO3
> So my opinion:
> First - H2SO4 for Ag and base metals, dilute 10:1 and drop with NaCl
> ...



Excellent - I have never used sulfuric acid to dissolve the silver.

That is an important tip; sulfuric will dissolve the silver but not the Pd, and the Pt will not dissolve with the silver like it does in nitric acid.

How come I have never heard of this?

Thank you amesametrita.

kadriver


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## kadriver (Mar 5, 2013)

I have a beaker with silver cell slimes washed from some anode baskets I had been saving.

The bottom of the beaker was coated with black material (PGMs and gold hopefully).

There were chunks of silver that did not dissolve still in with the slimes - I picked those out and added them to my anode basket of my operating cell.

Then I added dilute nitric and boiled to dissolve the silver.

This means that the Pd and probably some platinum went into solution with the nitric boil creating more steps to try and seperate them from each other.

I wish I would have used the sulfuric acid treatment instead - but I did not know about it (or I may have seen it somewhere here on the forum and it went right over my head).

Things can do that you know, go right over ones head, especially if I have tunnel vision.

Another valuable lesson learned. This forum is excellent!

kadriver


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## kadriver (Mar 5, 2013)

Could I just add zinc turnings and cement EVERYTHING out of the niric solution, incinerate the resulting solids, then treat with sulfuric to remove the silver and go from there?

New stuff all over again - I love it!

kadriver


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## amesametrita (Mar 5, 2013)

kadriver said:


> How come I have never heard of this?


Should I start a new flame war about this forum misconceptions?


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## goldsilverpro (Mar 5, 2013)

> Should I start a new flame war about this forum misconceptions?



Please don't.


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## Palladium (Mar 5, 2013)

What's up with the all the time slight of hand remarks? Chris just warned you several times as well as others. Chris was even trying to be nice to you and respect your knowledge. I respect your knowledge, but your attitude needs to STOP NOW! I've had enough of it. Keep it up and i will do my damest to have you banned. That's it no more warnings. All you had to do was state that you believed that was the best method and if anyone care to debate it that was fine. Not Blah Blah Blah.... Flame war this and that. Debates are welcomed here but you constant need not to conform to policy is not. Your starting to remind me of the good Doctor who couldn't reveal his name or sources and was all the time being counter productive.


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## Lou (Mar 5, 2013)

Misconception how?

It was already mentioned and not just by me. I know I talked about it. We occasionally run Pd sulfate solutions.


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=14664&p=147567&hilit=palladium+sulfuric+acid#p147567


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## amesametrita (Mar 5, 2013)

Palladium said:


> ...i will do my damest to have you banned...


Let's assume you have succeeded.
From now on I'm silent.


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## Palladium (Mar 5, 2013)

I don't want you to be silent, just civil and not so confrontational.


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## nickvc (Mar 5, 2013)

I too feel you have a lot to offer, perhaps it's because English isn't your first language, even though you are very fluent, perhaps the nuances in it are missing. Try to understand that we want input from those with knowledge and with ideas to share but we are not at school and no one likes to be talked down to and we certainly do not want the forum disrupted because of ego trips or arguments that are counterproductive to the running of the forum, even the moderators are polite and civil to the members even when they do step out of line on odd occasions.
Remember no one knows it all and most of us will be learning something new till the day we leave this mortal plane especially where this particular subject is concerned so lighten up and become a backbone of the forum not a thorn in its side, we need all the knowledge we can get.


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## butcher (Mar 6, 2013)

Amesametrita,

H2SO4 I have read many times as a way to treat silver cell slimes, I have not paid too much to the details, as I do not have slimes to work with at this point, But I am sure I could go back and study them when needed.

“Should I start a new flame war about this forum misconceptions?”

We do wish for you to become one of our finer members, sharing with us what you can, but we will not have thorns in the side on this forum, you have a choice play nice or do not play at all, we would love to have you here learning and sharing, but we will not put up with games, we can learn what we need without all of that kind of trouble.


As one of our founding fathers has said many times we do not suffer fools gladly.
So just stop playing these foolish games, enjoy the forum, Who knows you may learn a thing or two and make some good friends.

If you think we have misconceptions let us discuss them in a friendly manner, we do not always have to agree on everything that is OK, you may or may not know more than another member on this forum, that is OK also, but starting a flaming war here is not OK, and will not be tolerated.

But if you continue with these games you will not be a member here.

Butcher


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## kadriver (Mar 6, 2013)

kadriver said:


> amesametrita said:
> 
> 
> > Diluted H2SO4 1:4 (water:acid) dissolves silver but not palladium.
> ...



I can answer my own question - because I am still a relative newbie, an advanced beginner if you will.

I have only processed silver cell slimes one time and I was able to get was a tiny bead of gold (but I was happy with that because it was my first attempt).

I had never heard of it because I had never take the time to search for this type of information.

I should have refrained from asking that question.

kadriver


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## skippy (Mar 6, 2013)

kadriver, I wouldn't have taken it badly, 'the why haven't I heard of this before?', 
because I would often hear this in English in a ironic sort of way, with it being said as a light hearted jab at one's own ignorance, or to express ones disappointment at not learning of something much earlier.
To say it 100% seriously would be a rash thing to say because it would imply either someone has been hiding something, or that the veracity or importance of the fact is in question. I doubt you meant it like that.


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## nickvc (Mar 6, 2013)

Kevin once you start to deal with volumes of these slimes, aptly named but I feel swines might be better, they really are a pain, they won't filter easily and they seem to get everywhere but where you want them. I'm not sure if you would need to filter them to remove the nitric first but if you do good luck, I'm sticking to Harold's method and boiling in nitric and concentrating the PGMs in silver chlorides and cemented silver for a final recovery when I intend to use the sulphuric method to get to them and mix them with other accumulated PGMs for melting and sale, I'm playing with around 100 kilos of silver jewellery in either bar form or cemented silver with around 5 kilos of chloride to convert, I know there is gold there and from what I'm seeing definitely platinum, palladium, rhodium and iridium, don't ask about that it's been haunting me for years, but I'm hoping by using the stainless cell and keeping the voltage low I can aggregate all the values for a final recovery, if I'm left with a final volume of 10 kilos in bars I'm sure I can recover all the values. 
This is all fun and it keeps me busy and it produces some beautiful crystals around 2 kilos a day and I'm now looking for other materials to run to keep it working 24/7, I never switch it off but simply lower the voltage when I'm not around and have fully changed the electrolyte 3 times while producing 50-60 kilos of crystal, it holds 11 litres of electrolyte and I'm running sterling until I run out then I'll switch to the cement silver which I'm hoping will be a doodle compared to the sterling, I might be wrong :shock:


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## mikeinkaty (Mar 6, 2013)

nickvc said:


> Kevin once you start to deal with volumes of these slimes, aptly named but I feel swines might be better, they really are a pain, they won't filter easily and they seem to get everywhere but where you want them. I'm not sure if you would need to filter them to remove the nitric first but if you do good luck, I'm sticking to Harold's method and boiling in nitric and concentrating the PGMs in silver chlorides and cemented silver for a final recovery when I intend to use the sulphuric method to get to them and mix them with other accumulated PGMs for melting and sale, I'm playing with around 100 kilos of silver jewellery in either bar form or cemented silver with around 5 kilos of chloride to convert, I know there is gold there and from what I'm seeing definitely platinum, palladium, rhodium and iridium, don't ask about that it's been haunting me for years, but I'm hoping by using the stainless cell and keeping the voltage low I can aggregate all the values for a final recovery, if I'm left with a final volume of 10 kilos in bars I'm sure I can recover all the values.
> This is all fun and it keeps me busy and it produces some beautiful crystals around 2 kilos a day and I'm now looking for other materials to run to keep it working 24/7, I never switch it off but simply lower the voltage when I'm not around and have fully changed the electrolyte 3 times while producing 50-60 kilos of crystal, it holds 11 litres of electrolyte and I'm running sterling until I run out then I'll switch to the cement silver which I'm hoping will be a doodle compared to the sterling, I might be wrong :shock:


Nick - How do you keep track of the silver depletion and the copper accumultion in your cells? Do you log the weight and purity of all the anode bars going in? Mike


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## nickvc (Mar 7, 2013)

Mike I'm a very much an instinctive refiner so I just judge by the colour of the electrolyte and when the crystal starts to change colour from that bright and white shade to a more grey colour, it's not very scientific but it's worked for me and in truth the quality of the silver is secondary to me as I'm after the other values but I try to keep the crystal as high grade as possible.


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## Palladium (Mar 7, 2013)

nickvc said:


> Mike I'm a very much an instinctive refiner so I just judge by the colour of the electrolyte and when the crystal starts to change colour from that bright and white shade to a more grey colour, it's not very scientific but it's worked for me and in truth the quality of the silver is secondary to me as I'm after the other values but I try to keep the crystal as high grade as possible.



Same here! I do most of my refining based on observation and knowledge. You can't always calculate exactly what you need or what is going on. As much as this is a science, it's not really a true science, to many variables. The best you can do is get close and then grab the wheel and drive it on in so to speak. A lot of refining is instinct.


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## nickvc (Mar 7, 2013)

Palladium you summed that up very well, you need to know what's happening and why but always keep all reactions under observation as variables have a habit of changing things and rapidly at times that can spell disaster....been there done that :evil:


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## kadriver (Jun 2, 2013)

mikeinkaty said:


> Nick - How do you keep track of the silver depletion and the copper accumultion in your cells? Do you log the weight and purity of all the anode bars going in? Mike



I have started using a photo spectrometer - it gives precise measurements of copper concentration in the electrolyte taking the guess-work out of electrolyte change-outs.

I judge the silver depletion a little differently. I gauge it by the amount of current I can flow through the cell.

With fresh electrolyte (I use 750 grams of pure silver crystal dissolved in 3.5 liters of liquid) I get about 2.1 to 2.2 amps flowing when the cell is first placed in operation.

This gives me a ratio of just over 200 grams of silver dissolved in one liter of liquid. For me, this makes for faster cell operation - I can get about 75 troy ounces of silver crystal in about eleven days.

As the silver depletes out of the electrolyte, the current flow will begin to fall off, plus the electrolyte level will drop (due to evaporation).

To correct the concentration of silver in the electrolyte, I will dissolve another 150 grams of silver in about 300ml of liquid and add it to the cell.

I cook this for several hours until no more fumes are given off, and there is just a few grains of silver crystal left in the bottom of the container to enure complete consumption of the nitric acid before adding it to the cell.

I tried adding nitric acid to the cell once and the electrolyte turned green and tested positive for palladium, so I prefer to add more silver nitrate instead to avoid dissolving palladium out of the anode basket filter.

kadriver


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## kadriver (Jun 2, 2013)

I elected to use the method Harold posted earlier in this thread.

I had about 1/2 inch depth of slimes saved in a 2-liter beaker.

Incremental nitric acid additions, with boiling for several hours until no more fumes and just a few bits of silver left in the bottom with the other sediment.

This will ensure complete consumption of the nitric acid.

I have allowed it to settle and will siphon off the palladium-rich and silver nitrate solution, then proceed to the next step.

The stannous test is positive for palladium. 

Next step is to add HCl to precipitate out the silver chloride - more to follow.


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