How to properly smelt Silver sulphide precipitated from KAgCn2

[silverpoision]

I do silver electroplating and when we wash the electroplated metal into water it has some dragout and the water slowly gets filled with KAgCn2(Silver potassium cyanide). What we currently do to recover the silver from the solution is we put an arbitrary amount of Sodium Sulphide and let the precipitate sediment overnight and the next day we just throw all the excess water into the drain with proper treatment done. Then we dry out the precipitated silver sulphide and then smelt it with an arbitrary ration of Soda ash, Potassium nitrate and borax. Now the question is, although I am able to recover a good amount of silver but the matte stuff left after the smelt is a lot. I really wanted to know how I can properly melt the AG2S and is there any other more efficient way to extract the silver from the silver potassium cyanide solution.

 

[kurtak]

Then we dry out the precipitated silver sulphide and then smelt it with an arbitrary ration of Soda ash, Potassium nitrate and borax.

Try using iron in place of the potassium nitrate & you will (&/or should) get more complete reduction of the silver sulfide to actual silver

The sulfur (in the sulfide) reacts with the iron creating iron sulfide which then slags off in the borax/soda ash leaving the silver sulfide reduced to silver

Though the potassium nitrate method does work it is trickier to get all the sulfide to completely reduce to silver so there is a likely hood of some silver going off in the slag

Rebar works best for this - here is an "old" discussion about smelting silver sulfide with iron (which is where I learned about) ---------

https://goldrefiningforum.com/threads/metals-from-picture-fixer-solutions.12404/

From that thread --------

The black material is probably silver sulfide. If so, the simplest method is to melt it with about 1/2 its weight of borax and a little soda ash, with several lengths of rebar in the crucible. The rebar should be long enough to stick out of the top of the crucible so it can be easily removed before pouring. The sulfur in the silver sulfide combines with the iron and reports in the slag. When poured in a mold, the silver sinks to the bottom and should be quite pure.

The material on the right looks like the brittle silver that is plated from fixer on a rotating cathode drum or plate. It is brittle because it contains silver sulfide and it appears to be from 90 to 95% pure silver. It is purified using the same rebar method as above.

You just want to make sure you bend the end of the rebar that goes in the crucible up (make a loop) otherwise the sharp end of the rebar can end up drilling a hole in your crucible

I have smelted MANY kilos of silver sulfide using this method

Kurt

 

[kurtak]

and is there any other more efficient way to extract the silver from the silver potassium cyanide solution.

The most common method for recovering gold &/or silver from cyanide solutions is cementation with zinc

However - if you are talking about the "washes" the wash water may (or not) be to dilute for that to work properly

Another possibility may be to set up a "pass through" winning cell

I don't have time right now to post about that - however if Jon or Deano see this maybe they can provide some links to things they have posted about that cell set up

Kurt

 

[silverpoision]

The most common method for recovering gold &/or silver from cyanide solutions is cementation with zinc

However - if you are talking about the "washes" the wash water may (or not) be to dilute for that to work properly

Another possibility may be to set up a "pass through" winning cell

I don't have time right now to post about that - however if Jon or Deano see this maybe they can provide some links to things they have posted about that cell set up

Kurt

According to my assumption the wash water contains 1-2 grams of silver per liter. Is it possible to recover the silver through electrowinning from this much diluted solution? Or if I use the zinc sedimentation method what is the recovery percentage and can you please guide me through the exact steps on how to use zinc to sediment the silver out and then how to properly melt it.

 

[Yggdrasil]

I do silver electroplating and when we wash the electroplated metal into water it has some dragout and the water slowly gets filled with KAgCn2(Silver potassium cyanide). What we currently do to recover the silver from the solution is we put an arbitrary amount of Sodium Sulphide and let the precipitate sediment overnight and the next day we just throw all the excess water into the drain with proper treatment done. Then we dry out the precipitated silver sulphide and then smelt it with an arbitrary ration of Soda ash, Potassium nitrate and borax. Now the question is, although I am able to recover a good amount of silver but the matte stuff left after the smelt is a lot. I really wanted to know how I can properly melt the AG2S and is there any other more efficient way to extract the silver from the silver potassium cyanide solution.

There should be s description in here some place.
Read the whole thread it is quite interesting reading in many facets of recovery and refining.

Edit to add link:
https://goldrefiningforum.com/threa...y-be-of-interest-to-members.22978/post-241077

 

[Yggdrasil]

I do silver electroplating and when we wash the electroplated metal into water it has some dragout and the water slowly gets filled with KAgCn2(Silver potassium cyanide). What we currently do to recover the silver from the solution is we put an arbitrary amount of Sodium Sulphide and let the precipitate sediment overnight and the next day we just throw all the excess water into the drain with proper treatment done. Then we dry out the precipitated silver sulphide and then smelt it with an arbitrary ration of Soda ash, Potassium nitrate and borax. Now the question is, although I am able to recover a good amount of silver but the matte stuff left after the smelt is a lot. I really wanted to know how I can properly melt the AG2S and is there any other more efficient way to extract the silver from the silver potassium cyanide solution.

Welcome to us.
I did not react fast enough so it is a bit late.
Here is something to study:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[silverpoision]

Try using iron in place of the potassium nitrate & you will (&/or should) get more complete reduction of the silver sulfide to actual silver

The sulfur (in the sulfide) reacts with the iron creating iron sulfide which then slags off in the borax/soda ash leaving the silver sulfide reduced to silver

Though the potassium nitrate method does work it is trickier to get all the sulfide to completely reduce to silver so there is a likely hood of some silver going off in the slag

Rebar works best for this - here is an "old" discussion about smelting silver sulfide with iron (which is where I learned about) ---------

https://goldrefiningforum.com/threads/metals-from-picture-fixer-solutions.12404/

From that thread --------



You just want to make sure you bend the end of the rebar that goes in the crucible up (make a loop) otherwise the sharp end of the rebar can end up drilling a hole in your crucible

I have smelted MANY kilos of silver sulfide using this method

Kurt

I have read the rebar method a number of time and I am planning to do performe the same soon. Can you please guide me to the exact amount of borax and soda ash needed and the temperature too.
One more question, does roasting the AG2s helps? If yes then at what temperature.

Thanks a lot for replying and giving me your valuable time.

 

[silverpoision]

Welcome to us.
I did not react fast enough so it is a bit late.
Here is something to study:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

I got you.
Thanks a lot

 

[Yggdrasil]

According to my assumption the wash water contains 1-2 grams of silver per liter. Is it possible to recover the silver through electrowinning from this much diluted solution? Or if I use the zinc sedimentation method what is the recovery percentage and can you please guide me through the exact steps on how to use zinc to sediment the silver out and then how to properly melt it.

Here is another link which talks about the Carbon felt cell Deano introduced to us.
Link: https://goldrefiningforum.com/threads/cyanide-destruction-disposal.25225/post-267351

 

[silverpoision]

The most common method for recovering gold &/or silver from cyanide solutions is cementation with zinc

However - if you are talking about the "washes" the wash water may (or not) be to dilute for that to work properly

Another possibility may be to set up a "pass through" winning cell

I don't have time right now to post about that - however if Jon or Deano see this maybe they can provide some links to things they have posted about that cell set up

Kurt

Can you please give answer to my questions I have asked in my previous reply? And one more thing to ask that how do I verify that there is no more silver left in my slag?
That will be so kind of you
Thanks a lot for all the help.

 

[kurtak]

Can you please give answer to my questions I have asked in my previous reply?

Sorry for the delay getting back to you & I don't really have a lot of time to post details today

As with all things refining there is always a "bit" of a learning curve to figuring out what works best for you in your particular situation so here are the basic to start with - you may (or not) need to make some adjustments to see where/how you get the best results

Can you please guide me to the exact amount of borax and soda ash needed

For the flux 50/50 borax/soda ash - it is "best" to use "anhydrous" borax

Then 50/50 flux/sulfide

and the temperature too.

2000 F - 2100 F (or 1100 C - 1150 C)

Smelt time (after everything becomes molten) about 30 - 45 minutes

One more question, does roasting the AG2s helps?

No - you do not need to "roast" it - you just want it to be good & dry

And one more thing to ask that how do I verify that there is no more silver left in my slag?

The best indicator that all the sulfide has converted to actual silver is when you see no more "reaction" taking place (no more foaming up in the crucible) then let the smelt run for (plus/minus) about another 10 minutes

If you have an XRF you can pull a sample of the slag - let it cool - then shoot the cooled slag with the XRF to verify

If/when I get more time I will post more details on adjustments you may (or not) need to make to the above

Kurt

 

[kurtak]

Here is another link which talks about the Carbon felt cell Deano introduced to us.
Link: https://goldrefiningforum.com/threads/cyanide-destruction-disposal.25225/post-267351

Thank for the link - but that thread is really more about using the pass through cell (carbon felt) to destroy the CN waste for safe disposal after the PMs have been recovered from the CN solution

Here is a link to Jon's pass through winning cell (inspired by Deano) for the recovery of the PMs from CN solutions

https://goldrefiningforum.com/threads/taking-a-great-idea-and-applying-modern-techniques.24899/

Kurt

 

[Yggdrasil]

Thank for the link - but that thread is really more about using the pass through cell (carbon felt) to destroy the CN waste for safe disposal after the PMs have been recovered from the CN solution

Here is a link to Jon's pass through winning cell (inspired by Deano) for the recovery of the PMs from CN solutions

https://goldrefiningforum.com/threads/taking-a-great-idea-and-applying-modern-techniques.24899/

Kurt

Thanks, I didn't find the correct thread when I searched.
Nice to reread it

 

[kurtak]

There should be s description in here some place.
Read the whole thread it is quite interesting reading in many facets of recovery and refining.

Edit to add link:
https://goldrefiningforum.com/threa...y-be-of-interest-to-members.22978/post-241077

The thread where Deano posted about how to actually build & run the pass through electro win cell starts about half way down on the first page of this thread

https://goldrefiningforum.com/threads/things-which-may-be-of-interest-to-members.21526/

Kurt

 

[silverpoision]

Thanks a lot all of you for the help. I will do the tests and update you guys with the results soon.