# Silver sulphide (What to do about it?)



## peter i (Aug 28, 2008)

I have some silver sulphide, and it's taunting me! (50 grams, so it's mainly for the principle, not the value)

I have identified it with certainty using X-ray powder diffraction, and all I need is a way to dissolve it.

I've tried konc. nitric, and very little happens. I can test positive for silver in the acid, but most of the black powder remains.

:twisted: 
Any ideas?


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## Harold_V (Aug 28, 2008)

Try reducing it by furnace. Get it molten and introduce some scrap steel. A length of rebar, for instance. Anything that can be retrieved after the conversion. Cover the sulfides with flux (borax and soda ash) and allow to cook a while. I've recovered values from sulfides that way with great success. The sulfide layer that I started with changed characteristics considerably in the process. 

Not guaranteeing it works (in your case), but it can do no harm. If it works, iron will replace the silver in the sulfide, reducing the silver sulfate to elemental silver. You'll see a distinct reduction of size of the iron where it contacts the silver.

Where the hell you been, Peter? Long time!

Harold


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## peter i (Aug 28, 2008)

Harold_V said:


> Try reducing it by furnace.




Nice idea! When nothing is around to reduce it, it melts and casts at a low red heat. That had me awfully puzzled until I found out that it was silver sulphide.

:lol: 





Harold_V said:


> Where the hell you been, Peter? Long time!
> 
> Harold





Thanks!
Well, you know, work and family both have a nasty tendency to kill the time used for other small projects (being admin in two other fora doesn't make it easier)

Add to that the weird virus that pops up whenever I use this forum, making the sysadm at work aware that I may be strolling around at the edge of relevance at times.....


:wink: missed you too!


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## goldsilverpro (Aug 28, 2008)

Don't forget to use the rebar. The sulfide will combine with the iron and will end up in the slag.


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## Lou (Aug 28, 2008)

I don't know how well this would work on a large amount, but one thing I did for silver instruments and items that tarnished is to put them in the furnace at red-orange heat and let air go over them, the silver will not oxidize but the Ag2S will! Maybe sparging or heating the sulfide with O2 source (chlorate might be too aggressive) or even in lots of excess air, that ought to do it!



Oh, I know that KOH fusion will work  You ought to be left with Ag2O


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## Lino1406 (Aug 31, 2008)

in the following:
HNO3
conc. H2SO4


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## goldsilverpro (Aug 31, 2008)

*Please don't mention KCN and any acid in the same post without going into great detail about what you're talking about!!!*

It sounds like you are suggesting that one should combine these chemicals. We don't want to kill anybody.

I have edited your post and removed the KCN.


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## Lino1406 (Sep 1, 2008)

I apologize


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## peter i (Sep 1, 2008)

The funny part is, that this silver sulphide is very reluctant to dissolve in nitric acid.

But the PXRD sees nothing else :?


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## Lino1406 (Sep 1, 2008)

argentite (black, cubic) so
try another acid with heating


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## Juan Manuel Arcos Frank (Sep 1, 2008)

Peter:

Handling silver sulphide (Ag2S) is a nightmare,but we have got to do it because silver easily reacts with sulphur.Ag2S is greatly insoluble so all silver compounds can be converted to silver sulphide.Most silver ores are Ag2S,called acanthite.

The big problem with Ag2S is its tendency to form colloidal solutions so filtering it could be a many days tedious labor.I propose you three ways to recover silver from silver sulphide:

FIRST.-Preparing a rare solution that dissolves the silver sulphide,this could be done with sodium thiosulphate(common photo fixer) and cooper sulphate.Just add a little copper sulphate to the fixer,stirr until it dissolves and this solution has the power of dissolving silver sulphide.Mix the sliver sulphide with this solution.You can recovery the silver exactly like you do with common photo fixers using a SRU or Zn and H2SO4 process.

SECOND.- Using CLOROX,add CLOROX to the silver sulphide, do it outside because it will foam and will form a grey mud instead black original mud,add tap water,let settle down,pour off the liquid and to the grey mud add common photo fixer.Recover the silver from the fixer as usual.

THIRD.- If you have the silver sulphide as a dry powder then add nitric acid,of course,brown fumes of NO2 will be released so do it outside.The nitric acid will react with sulphide to form silver nitrate so let settle down,pour off the liquid,wash three times the dark yellow mud with tap water,add the washes to the liquid and recover the silver adding common salt ,caustic soda and Karo syrup.

Peter,by the way,in this forum we are a large family,do not go away for so long time.

Have a nice day

Manuel


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## peter i (Sep 5, 2008)

Thanks, I'm glad to hear that silver sulphide is a nightmare for others too!

(Not that I wish ill for others, but at least I'm not totally incompetent)

I've tried to let a pinch of the powder soak for a couple of days in nitric, and I'm going to PXRD the remaining sludge to see if it is still silver sulphide, or some other contaminant (I would not be surprised to find some silver chloride too).

The solution tests positive for silver, so at least something is dissolving...


I'll keep you posted


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## peter i (Sep 5, 2008)

The powder got a grey-ish colour, and PXRD was inconclusive :evil: 

It will now spend a (hopefully unpleasant) weekend in 50-50 nitric/water, and I'll look at it on monday.


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## OMG (Sep 21, 2008)

This seems like a dumb suggestion but I don't care. Maybe it will help. :?
You know how you remove silver sulfide tarnish from utensils.. Aluminum foil covered with a mix of hot water and sodium carbonate. The aluminum has a greater attraction to the sulfide than the silver does, so it grabs it leaving the silver pure. (using galvanic action or something like that)
Maybe you could adapt this somehow to let the energy stored in aluminum do all the work for you instead of the acids. The aluminum would be wasted, but its cheaper than acids.


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## Juan Manuel Arcos Frank (Sep 21, 2008)

OMG:

Yes.Sir...it will work too
.
Regards


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## Anonymous (Sep 21, 2008)

is silver sulfide conductive? if so couldn't you put it is an electrical cell and convert it to something easier to process or even close to fine silver?


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## Juan Manuel Arcos Frank (Sep 21, 2008)

James 122964:

No it is not conductive,that is exactly the problem.When silver sulphide is formed in an ESRU (Eletcrolytic Silver Recovery Unit) the silver recovering goes down and it is a nightmare,besides Ag2S tends to form colloidal solutions that never precipitate.It is better to avoid it,if you can.

Have a nice day

Manuel


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## Anonymous (Feb 22, 2009)

if you wish to disolve oxides from silver try this mix a solution of 20 parts of water , 4 parts thiourea and 1 part sulfuric acid it will disolve it in 1/10 of 1 second rooster


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## educationalcoin (Jun 14, 2011)

request: Are there commercial refiners that will effectively process silver sulphide? I have accumulated ca. 80 lbs. dry powder from the processing of shipwreck salvaged silver coins. I am located northeast USA. 
Thanks, robin


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## Harold_V (Jun 14, 2011)

educationalcoin said:


> request: Are there commercial refiners that will effectively process silver sulphide? I have accumulated ca. 80 lbs. dry powder from the processing of shipwreck salvaged silver coins. I am located northeast USA.
> Thanks, robin


Can't speak for major refiners, but it's not beyond your capability, assuming you have an interest. A furnace (home built) that is natural gas or propane fired would be more than adequate, and with silver at near record highs, it should pay for your trouble. 

Before taking the plunge, it might be wise to run a sample by torch to see what kind of results you achieve. 

Harold


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## NoIdea (Aug 16, 2011)

Hi – Not sure about it’s conductivity but I have successfully electroplated non-conducting material (a dry leaf) by lightly coating it first with shellac dissolved in standard methanol/ethanol (the blue stuff from the local shop), allowing it to dry, then spraying it with a water/ethanol/silver nitrate solution and allow to dry. With homemade iron sulphide and acid (I used HCl) to produce H2S gas. The leaf was suspended from the inside of the lid of a jar in which sat the HCl and iron sulphide (I added dilute HCL just before I put the lid on). The silver nitrate changed/converted to silver sulphide (The leaf turned black). The leaf had copper electroplated on it using a simple H2SO4 electroplating cell. Sorry can’t remember the details, but it was a long time ago, well before my varsity days when I thought I knew everything. :lol: 

*Note: H2S is a very poisonous gas, use ventilation and great care, and only make what you need. Alkai solutions will strip any excess H2S if you are using a scrubber or just go outside with it*


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## rusty (Aug 16, 2011)

I used to work in the oil field the trucks that worked on sour gas ( H2S ) had a tank with ammonia to scrub out the H2S. I'm not sure at what concentration the ammonia was so I made a telephone call the company I used to work for.

The fellow from the shop informed me that they no longer use ammonia as a scrubber, he suggested that I make a call to any one of the oil field chemical companies to get some of the new stuff which does not have the nasty irritating eye watering, lung wrenching oder of ammonia.

If I get a chance to follow this up later in the week I will post the name of the chemical used to scrub H2S.

Regards
Rusty


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## rusty (Aug 18, 2011)

NoIdea said:


> Hi – Not sure about it’s conductivity but I have successfully electroplated non-conducting material (a dry leaf) by lightly coating it first with shellac dissolved in standard methanol/ethanol (the blue stuff from the local shop), allowing it to dry, then spraying it with a water/ethanol/silver nitrate solution and allow to dry. With homemade iron sulphide and acid (I used HCl) to produce H2S gas. The leaf was suspended from the inside of the lid of a jar in which sat the HCl and iron sulphide (I added dilute HCL just before I put the lid on). The silver nitrate changed/converted to silver sulphide (The leaf turned black). The leaf had copper electroplated on it using a simple H2SO4 electroplating cell. Sorry can’t remember the details, but it was a long time ago, well before my varsity days when I thought I knew everything. :lol:
> 
> *Note: H2S is a very poisonous gas, use ventilation and great care, and only make what you need. Alkai solutions will strip any excess H2S if you are using a scrubber or just go outside with it*



Another word of caution when working with H2S is that the gas will infuse into the liquids only the be expelled on shaking or movement of the vessel to make sure all the gas has been expelled and run through your scrubber heat the solution to drive off excess gas through your scrubber.

I can not express enough the danger of working around or with H2S, there have been fatality's where men have entered empty storage tanks with a couple of inches of water on the floor. The tank was tested for gas before entering with a H2S detector which showed all clear. Once the men walked through the water enough gas was released to cause death.

Lucky for me I never encountered a situation where there was a man down, in our training we were taught to curb our natural instincts to rescue a man down, grab a respirator before going in for the rescue. 

So may people have died attempting to rescue another man down by dodging in for that quick rescue without the proper gear only to go down as a second victim.

I wore an H2S detector , damn thing was going off all the time, even when I could not smell H2S in the air. Located at several locations around the drilling rig you will see wind socks, if your detector beeps, the first thing you look at is the sock to get a fix on wind direction so your not moving into the danger zone but out of it.

It's PPM of H2S that are enough to kill you, there is no known antidote - sometime luck plays a part in survival but this is rare. Mos people encountering H2S seldom live to talk about the experience.

The manufacture of H2S is in C.W. Ammens book, which is now freely available to all., but I do not think that there has been enough written about the cautions and just how dangerous the gas is to human life.

My advice is not to use it.

Regards
Rusty


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## NoIdea (Aug 18, 2011)

Well said Rusty.

I treat each an every chemical with the respect. The chemical incompatibility list is huge for the chemicals listed and used by members of this forum. I was a bit nervous about the post for this reason.

In another post I explain how H2S a precursor for electroplating non-conduction objects by converting silver nitrate to silver sulphide as the electro conducting substrate. I was aware at the time it was poisonous even way way back then. Unfortunately the use of chemicals involves common sense, which is lacking in a lot of people.

If one lives to be my age and has done the things I’ve done, you tend to prepare for what might happen if you mix A with B. Look it up, see what might happen, take precautions and never under any circumstances become complacent. It will eventually come back and bite you in the butt if you do.

Happy processing

Deano


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## shpfrm14 (Oct 17, 2011)

Used aluminum kettle, aluminum foil, heated on hot plate with sodium carbonate. Put sample of soil from prospect site, strange colored soil + sparkly in pot. It foamed and frothed over the sides. Removed from heat, transfered liquid to another container. My aluminum pot, is now dark grey below water line and appears to be gold plated with metallic silver white splotches on top of that. Above the water line the pot is still shiny aluminum. I haven't had time to check what is in the water. What kind of pot should be used to avoid plating?


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## Windnsails (Jun 15, 2022)

shpfrm14 said:


> Used aluminum kettle, aluminum foil, heated on hot plate with sodium carbonate. Put sample of soil from prospect site, strange colored soil + sparkly in pot. It foamed and frothed over the sides. Removed from heat, transfered liquid to another container. My aluminum pot, is now dark grey below water line and appears to be gold plated with metallic silver white splotches on top of that. Above the water line the pot is still shiny aluminum. I haven't had time to check what is in the water. What kind of pot should be used to avoid plating?


Did you ever find out what happened?


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## Yggdrasil (Jun 15, 2022)

Aluminium should not be used in such conditions.
It reacts with many/most acids and many/most alkaline solutions.
The foaming was probably the Aluminum dissolving.


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## Windnsails (Jun 22, 2022)

shpfrm14 said:


> Used aluminum kettle, aluminum foil, heated on hot plate with sodium carbonate. Put sample of soil from prospect site, strange colored soil + sparkly in pot. It foamed and frothed over the sides. Removed from heat, transfered liquid to another container. My aluminum pot, is now dark grey below water line and appears to be gold plated with metallic silver white splotches on top of that. Above the water line the pot is still shiny aluminum. I haven't had time to check what is in the water. What kind of pot should be used to avoid plating?


Perhaps use a stove top Corningware / non-metallic pot. You’re just heating this mixture, not melting it. Just a thought.


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## ION 47 (Jul 16, 2022)

Mix sodium carbonate with silver sulfide, melt, add iron (stir the melt with iron fittings). Iron will restore pure silver from sulfide.


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