What to do with Anode Basket Slimes

[ModernAlchemy]

I'm new to the Silver Cell and first off would like to thank all of you for your support in answering questions. This forum has been a jewel of info. Now back to the question. What do I do with the Slimes in my anode basket? Neutralize and discard properly or can they be used for something? Please advise...

 

[Shark]

As with other cell’s, any pm’s or pgm’s will be left in the slimes. Removing some of those and collecting these for further refining can add extra money to the process. The method used to further refine the slimes will be based off what is in them. If you’re running a smaller cell, you may be better off to hold them until you have a reasonably large amount.

 

[ModernAlchemy]

Thank you so much for the reply!!

 

[4metals]

The industry average for silver from sterling silver runs about 1/3 of an ounce per 1000 ounces refined. Often some sterling was gold
electroplated and in time the Gold migrated into the Silver and looked like it was never plated. That is where the Gold comes from. Also some Sterling was flash electroplated with Palladium, to inhibit tarnishing, back when Palladium was cheaper. It is not as consistent as Gold in the slimes but it can accumulate in the solution as well. A test with Dimethylglyoxime will detect any Palladium in the solution. Usually the most abundant metal in the slimes from a silver cell is Silver.

 

[ModernAlchemy]

Very good info! Most appreciated!

 

[Paul Allee]

Suppose someone was running a silver cell and accumulated a lot of filters of anode slimes, could you put them all in a crucible and add some borax and salt peter and smelt it? If the main slime is silver could you just make shot with the smelt and run it back through?

 

[andu]

You would need to test if and how much silver it is or you could clog your filter in vain if you just turn it to metal.

No idea if you can simply go and melt it but should be so, and whatever else will stay in the flux if i'm not wrong.

I tend to avoid use of flux if possible.

 

[cejohnsonsr1]

If you want to see an excellent demonstration of how to process the filters and slimes, Sreetips has a couple of good video series.

 

[Darkthirty]

The industry average for silver from sterling silver runs about 1/3 of an ounce per 1000 ounces refined. Often some sterling was gold
electroplated and in time the Gold migrated into the Silver and looked like it was never plated. That is where the Gold comes from. Also some Sterling was flash electroplated with Palladium, to inhibit tarnishing, back when Palladium was cheaper. It is not as consistent as Gold in the slimes but it can accumulate in the solution as well. A test with Dimethylglyoxime will detect any Palladium in the solution. Usually the most abundant metal in the slimes from a silver cell is Silver.

I was of the impression sterling was 92.5% silver.

 

[Shark]

I was of the impression sterling was 92.5% silver.

It is. What 4metals is saying is that an average of 1/3 of an ounce of gold can be recovered in the slimes from 1000 ounces of sterling. Especially if you’re running older sterling materials.

 

[nickvc]

Running the slimes is a real pain even collecting them is a nightmare they get everywhere, most of the material you have will be undissolved silver with the other values in fairly low percentages but worth recovering if you have reasonable amounts. The problems start if you have PGMs in the mix as they happily dissolve in nitric with the amount of silver present but if only in small amounts then dissolve the material in nitric which will leave the gold which can then be refined.
I believe one method with slimes was to put them in an iron pot with dilute sulfuric and then heated to dissolve the silver leaving the other values for further refining.
Whichever method you choose they are still a pain in my opinion I ended up calling them swines…

 

[kurtak]

Suppose someone was running a silver cell and accumulated a lot of filters of anode slimes, could you put them all in a crucible and add some borax and salt peter and smelt it?

Per the bold print (salt peter) - NO - salt peter is potassium nitrate - when smelting any kind of material that has silver in it (such as ore containing silver, silver plated copper/brass, silver slimes from silver cell etc. etc.) you never want to use potassium nitrate (or any other nitrate) as part of your flux ingredients

The reason for that is that nitrates used as a flux ingredients basically become nitric acid at the high temps of smelting - so when the flux becomes molten - any metals in the smelt - that will dissolve in nitric acid - will then also be dissolved by the nitrate in the flux causing (at least some of) those metals to then go off in the slag

So - using potassium nitrate - as a flux ingredient - is a good option if you are smelting gold with copper in it as the nitrates will dissolve the copper & thereby allow the copper to go off in the slag

You just don't want to use potassium nitrate (or any other nitrate) - as a flux ingredient - if what you are smelting has metals in it that will dissolve in nitric acid - metals such as silver or palladium - as those metals will dissolve in the smelt & go off in your slag - instead of collecting with your dore (alloy) that you are wanting to settle in the bottom of your cone mold when you make your smelt pour

Kurt

 

[4metals]

Typically in a silver refinery the slimes are collected, a messy and nasty proposition, and remelted into an anode again. This is done because it is typically high Silver content. The anode is then placed in a specific anode location in the silver cell where the normal process of the Silver cell will recover the Silver and further concentrate the other values in the slimes. By keeping the “slime” anodes in a specific anode compartment the refiner can collect the slimes from that particular anode location and process them for the “bonus metals”. This method is obviously not available in a small hobby cell or a single thum cell.

 

[kurtak]

Suppose someone was running a silver cell and accumulated a lot of filters of anode slimes, could you put them all in a crucible and add some borax

Concerning the anode bags (filters) you don't want to just put them in a crucible with flux - they should first be ashed (burned) - you can then smelt the ashed filter

However - when ashing filters there is a right way to do it & a wrong way to do it - if you don't do it right "some" of your silver is likely to go up in smoke

Read what I posted about ashing filters in this thread (near bottom of the page)

https://goldrefiningforum.com/threads/incinerated-filters-and-pm-salts-recovery.21638/page-2
Kurt

 

[nwinther]

Couldn't you dissolve the anode slimes in Nitric acid and then cement out the PGM's on some sacrificial silver (maybe elemental Silver crystal from the cell)?

 

[Martijn]

Couldn't you dissolve the anode slimes in Nitric acid and then cement out the PGM's on some sacrificial silver (maybe elemental Silver crystal from the cell)?

Yes, all those PGM's that are soluble in Nitric acid alone can be cemented out on copper, but I'm not sure if silver works for PGM's.

 

[nickvc]

If you do decide to try the nitric route to dissolve the silver and probably all the PGMs the easiest method to separate the silver is convert it to chloride and filter off the solution and then cement the PGMs in the solution on to copper.
An interesting note is that if you simply cement all the metals dissolved in the nitric onto copper leaving just the gold separated you can see the silver slowly change to a grey color once the PGM concentration builds up if you constantly reuse the silver ,
the same as it does when you inquart , this visual aid may help to determine when to recover the PGMs as a worthwhile exercise.

 

[Paul Allee]

Per the bold print (salt peter) - NO - salt peter is potassium nitrate - when smelting any kind of material that has silver in it (such as ore containing silver, silver plated copper/brass, silver slimes from silver cell etc. etc.) you never want to use potassium nitrate (or any other nitrate) as part of your flux ingredients

The reason for that is that nitrates used as a flux ingredients basically become nitric acid at the high temps of smelting - so when the flux becomes molten - any metals in the smelt - that will dissolve in nitric acid - will then also be dissolved by the nitrate in the flux causing (at least some of) those metals to then go off in the slag

So - using potassium nitrate - as a flux ingredient - is a good option if you are smelting gold with copper in it as the nitrates will dissolve the copper & thereby allow the copper to go off in the slag

You just don't want to use potassium nitrate (or any other nitrate) - as a flux ingredient - if what you are smelting has metals in it that will dissolve in nitric acid - metals such as silver or palladium - as those metals will dissolve in the smelt & go off in your slag - instead of collecting with your dore (alloy) that you are wanting to settle in the bottom of your cone mold when you make your smelt pour

Kurt

Thank you that makes so much sense and explains why I only had a copper bead after one of my previous smelting experiments. I figured as much but that confirms nicely.

 

[nwinther]

Yes, all those PGM's that are soluble in Nitric acid alone can be cemented out on copper, but I'm not sure if silver works for PGM's.

PGMs are last in the reactivity series, so they should cement out on silver.
It would be a way to reduce silver content in the mix to a minimum.

 

[Yggdrasil]

PGMs are last in the reactivity series, so they should cement out on silver.
It would be a way to reduce silver content in the mix to a minimum.

I'm not sure Silver lends itself to cementing well at all.
Copper is a good cementer though.