# Recovery of Silver from Spent Plasma TV Monitors



## Ardibash

Hey guys, any one knows anything about this process? 

"The method of extraction of silver from scrap of plasma TV monitors using noncyanide reagents – sodium thiosulfate and acidothiourea – was investigated, which was followed by silver recovery from acidothiourea leach solutions. It was found that acidothiourea solution gave almost complete extraction of silver while thiosulfate provided only 40% extraction. The rate of silver extraction using acidothiourea solution was found to be extremely fast. An increased dissolution rate was also found at elevated temperature. The recovery of silver through coagulation-precipitation from acidothiourea leach solutions was carried out with a natural biodegradable material, persimmon tannin extract. It was proved to be a promising material for complete silver recovery. Besides, precipitative recovery of silver by means of cementation with zinc powder was conducted. It was found that simple cementation with zinc powder exhibits a very good precipitative property for which it could be used in hydrometallurgical processing."


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## butcher

Is this something you found on the intranet?


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## Ardibash

Found it on 2011 TMS Annual Meeting & Exhibition, The Second Symposium on the Recycling of Electronic Wastes.


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## kuma

Hi all , how are tricks today?
I hope all is well!



butcher said:


> Is this something you found on the intranet?



I have this pdf stored on my laptop. I came across it some time ago and it is where I discoverd that plasma screens contain silver.
What I got from this is that you can crush to powder the silver bearing part of a plasma screen , follow that with a leach ( even as a noob , I would strongly suspect that you could probably choose from a multitude of other leaches other than just that described in the PDF [?] ) , then filter the solution , followed by precipitation of the silver.
I havn't studied the pdf intimatly , I've just briefly looked at it and this is what I gleamed from it.
Would I be right in guessing that there's something wrong here ? :roll: 
I only ask , as you asked! :lol: 

Heres the pdf ; View attachment Extraction Of Silver From Flatscreen Monitors.pdf


All the best for now , and kind regards ,
Chris


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## Ardibash

kuma, I have the exact same PDF  The thing is I can get 100 tons of broken Plasma TVs a month, and all that for free (almost free, just the cost of transport). So it could be a pretty good business, to strip recycle them. There are many values in Plasma and LCD TVs.

1. Gold from PCBs
2. Silver from screen.
2. Acrylic, polycarbonate and other transparent polymers from screen, if granulated it's worth more than £1500 a ton.
3. ABS PC plastic alloy, £1200 a ton.

Do you guys think an ordinary nitric leach will do the trick?


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## kuma

Hi Ardibash , how are things?
I hope your well!



Ardibash said:


> Do you guys think an ordinary nitric leach will do the trick?



This was my first thought , but I would guess that the release of large clouds of NO2 , coupled with the high price ( and in many cases for a lot of , if not most of us , the general unavailability of nitric ) , would probably make other leaches more prefferable for the extraction of silver from plasma screens due to the larger volumes of acid potentialy required.
Being a general noob I realy don't know , but that would be my first guess , :?: :roll:
It would be interesting to hear what those with experience think! 
Nice find too by the way! 8) 
All the best with it , and kind regards ,
Chris


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## butcher

The data in paper link posted, seems to be a paper written to try and find a way to avoid cyanide, but it does not look like they experimented enough with it to show the method would work any better than some of the other methods we may use, although they got a better extraction with this method than they did with thiosulfate method they also expierimented with, the acidothiourea it also sounds a bit complicated to me, I just briefly scanned the article but I will read it in more detail later.

I agree with Kuma some other acid treatment would be easier in my mind.

I have tore apart several LCD screens, have separated parts for recovery, but besides a thin sheet of plastic that may contain silver (gray powder coated), I have not seen any other part that looks like it may contain silver, I have not tested the sheet, but if it is where the silver is it would be like processing film, or Mylar from key boards.
I know there is some valuable metals in the LCD monitors but I do not know that I have seen enough to get me excited, when I get close to a ton of them and try processing them I may feel different, I am exited over the thick Acrylic, polycarbonate sheet though I have several ideas for these.


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## kuma

Hello butcher , how are things?
I hope your well!



butcher said:


> I agree with Kuma some other acid treatment would be easier in my mind.



Jusy my noob assesment chief! :mrgreen: 



butcher said:


> I am exited over the thick Acrylic, polycarbonate sheet though I have several ideas for these.



It will be fastinating to see what you come up with! 
I've sent plenty of these from LCD monitors off to the recycling center but it does pain me , they're such nice clean pieces of acrylic that I've always thought that there must be a good use for them , it would just be a case of holding on to them untill I figure I out what , and I don't think Gemma's too keen for any more clutter at home just now! :lol: 
All the best for now , and kind regards ,
Chris


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## Ardibash

Hi Guys,

ONE IMPORTANT THING! This is about PLASMA TVs not LCDs, LCDs contain indium, Plasmas contain silver.

There is also a lot of gold in them, I would imagine more than a modern mother board (without RAM and CPU), not sure tough. Some silver near the gold plated connecting points.
I will take some photos and post them this evening.


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## butcher

Ardibash, 
I have not dismantled the plasma TV’s, I was thinking the LCD computer monitor's. 
I would be very interested in pictures of the plasma televisions and components, these are becoming very popular so I expect I will be seeing inside some soon..

I believe the indium tin oxide is a liquid form between the glasses in the LCD crystal computer monitors.

That makes more sense to me now that the silver may be in the plasma TV’s, thank you for straightening me out on that point.

Kuma I am such a packrat, just cannot seem to give up something that I may be able to use or make something out of (I suppose it comes from growing up so poor), one day I may be buried alive in my junk, luckily I have six acres, and a huge barn (I can barley get into), but it has gotten out of hand, My wife is afraid I am going to die and leave it to her. Chris, Gemma is right she is keeping you from being buried too. I have been thinking of the trouble you are having with a place to refine and run your lab, I hope things work out for you, so you can have the best of both worlds (family and a nice lab).


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## kuma

Hey chief!
I hope your well! :mrgreen: 



butcher said:


> Kuma I am such a packrat, just cannot seem to give up something that I may be able to use or make something out of (I suppose it comes from growing up so poor), one day I may be buried alive in my junk, luckily I have six acres, and a huge barn (I can barley get into), but it has gotten out of hand, My wife is afraid I am going to die and leave it to her. Chris, Gemma is right she is keeping you from being buried too. I have been thinking of the trouble you are having with a place to refine and run your lab, I hope things work out for you, so you can have the best of both worlds (family and a nice lab).



Your kind words mean much to me , and your right!
My Gem keeps me from trouble , and if I had six acres she (we) would seriously struggle!! :lol: 
It will take a little bit of time chief , but as I hope your aware of by now I have all of the time and patience in the world ( contrary to what I would have you believe , it's just not that easy! )
My Gemma is my rock , and you guy's are my anchor.
It will happen as and when it can , and if I somehow fail you guy's , that will be my bad.
Just as long as you know , that failing is not part of my game plan , I'm here to stay , and I will make it work.
Peace and love to you my brother , 
Much respect and kind regards , 
Chris


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## Ardibash

Here We Go Guys, thise came out of one LCD TV + 17KG of steel, 2 Kg of ABS, and 0.5 Kg of Acrylic.


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## butcher

Ardibash,
Thanks for picture's, it does look there is gold and PGM, on board, did you find the silver?
there could also be some gold on the glass where the mylar connects to glass screen?


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## Ardibash

butcher said:


> Ardibash,
> Thanks for picture's, it does look there is gold and PGM, on board, did you find the silver?
> there could also be some gold on the glass where the mylar connects to glass screen?



The silver is, where the maylr connects to the gold. but the main idea is to extract indium, which is notoriously difficult. 
Do you think it would have a better yeild than modern mother boards? 

BTW Thanks for the info on depopulating SMD from a PCB.! 8)


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## g_axelsson

butcher said:


> I believe the indium tin oxide is a liquid form between the glasses in the LCD crystal computer monitors.


That's wrong! The indium tin oxide is the thin solid conductor on the glass that forms electrodes. The liquid beween the glass panes are a liquid crystal that has the power of rotating polarized light and consists of organic molecules.
The reason indium tin oxide is used is that it both conducts electricity and it is transparent so it doesn't block the light.

This thread also makes a mess between LCD technology and plasma.
- LCD : Light passes from a backlighter through a polarizing filter, then through liquid crystal. Depending on wether an electric field is present or not, light is rotated 90 degrees or passed through unaffected. A second polarizing filter stops any light that hasn't been rotated. That way a pixel is turned on or off.
http://en.wikipedia.org/wiki/Liquid-crystal_display
- Plasma : Every pixel is a small electronic tube, a mini CRT. The light is created when a current is applied and electrons strikes a phosphor in the front. As the light is created in the front part of the screen, only one of the electrodes needs to be invisible and are made of indium tin oxide (ITO). The back electrode doesn't need to be transparent and I suspect that this is made of a screen printed silver electrode, just as in keyboards.
http://en.wikipedia.org/wiki/Plasma_display

WARNING : Plasma displays contains mercury in the gas inside. Also backlighters for LCD:s commonly contain mercury in the backlighter, the cold fluorescent light bulbs. (long thin white glass tubes) Do not break them.

Göran


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## skyos

Hi everybody,

just try to find some silver in flat plasma but nothing is coming.

So, first, we dismantle plasma tv : plastic and different kind of boards.

After this , we take away the first dark windows, then , have only the steel or aluminium support with one glass with white film.

I believed that some silver stay inside this thin white film stick on the second windows.

So we broken all this windows, and some thick glue backside.

After my refinner friend burned all (glass, white film and glue), make ashes, reduce size to 200 microns.

We have 3.3 kilogrammes of powder, put 1 kilogramme of this powder inside furnace with 1 kg of borax....

and.....nothing lol

Did somebody find something inside this white film ?

thank you to all


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## rickbb

It's odd, I can find plenty of info that says there is as much as 40 grams of silver in a 32" plasma TV but I can't find anything that says which component of the TV it's in.

It's looking like the screen may have none and the silver is everywhere else, button switches, solder, etc.


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## skyos

Hi rickbb,

I think I follow you to the same conclusion, I read same as you many papers that say we can find more than an ounce of silver per screen.

I kept many flat panel for several years in my warehouse and now, when try to find it, nothing.... :x


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## rickbb

It would be nice to find out just where to look for this elusive silver. 

I have about 100 42" plasma screens gathering dust in the corner of the warehouse.

I'd rather have 100 ozt. of silver instead.


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## skyos

My friend just make an assay about this ashes and ....fing 26 g of Ag by screen :shock: 

I am buying Thiourea and Sodium sulfide now.

Will keep you inform in the next days...

Best regards


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## rickbb

This was the ashes from just the screen components?


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## skyos

This is ashes from the internal glass that is stuck on the steel / aluminium sheet.
When i burn this i only try to take away all the thick glue backside the glass.






http://www.casimages.com/img.php?i=140609042039491789.jpg

After this, we reduce it to some 200 microns powder and try to smelt it, but nothing come down...

After this try to assay this powder and find 26 gramms of Ag for one screen...

That s why i need to try the thiourea leaching on this ashes....I keep here 10000 plasma panels, if it really have 26 gramms for 1 screen and i can transform these ugly screens in beautiful 260 little 1kg ingots...I will not use so much space in my warehouse :lol: :lol: :lol: .....


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## Pantherlikher

Following along intently. Have either one of you tried dissolving some in nitric acid and seeing if any silver drops using copper?
This would help confirm silver. 
Grinding glass to a powder will be difficult for most as shards of glass are as dangerous as acids we use. So before diving into the deep end and make a grinding/ processing station for glass; it would be nice to find out if it is worth the effort.

Keep us informed please.

B.S.


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## modtheworld44

Pantherlikher said:


> Following along intently. Have either one of you tried dissolving some in nitric acid and seeing if any silver drops using copper?
> This would help confirm silver.
> Grinding glass to a powder will be difficult for most as shards of glass are as dangerous as acids we use. So before diving into the deep end and make a grinding/ processing station for glass; it would be nice to find out if it is worth the effort.
> 
> Keep us informed please.
> 
> B.S.




Pantherlikher

Watch this video from the three minute mark and see if this is enough confirmation.
http://www.kitco.com/news/video/show/Kitco-News/685/2014-06-09/A-Compelling-Story-For-Silver-IPMI-Speaker



modtheworld44


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## rickbb

I took one apart this weekend. The model I have looks like it not only has silver but gold as well. 

There is a huge Al board that the plasma panel is glued to with a thick foam backing. Like a 1/8" thick foam double sided tape, hard to remove.

The bottom glass in this sandwich appears to have tiny gold wires, like bonding wires, running the horizontal direction. The problem is, these gold "looking" wires are under a coating similar to a white ceramic like coating that forms the tiny cells of the plasma gas and/or the phosphorus that illuminates the cell.

The top layer glass, on the side facing into this white coating of cells has what appear to be lines of silver and a black material running along the vertical. Each row of black line has 2 rows of smaller silver wires. This is also under a coating of some sort, but it's clear. Like a lacquer or such.

I have a sample of each soaking in HCL, the clear coating seemed to dissolve in a few hours, the white does not look affected. I've left them in overnight and will check them after work today.

I tried various solvents to attack these coatings, nothing seemed to touch it. I did try a propane torch and the clear melted back with the silver "looking" wires melting and beading up nicely. The torch did nothing to the white coating over the gold "looking" wires.

I say gold and silver "looking" because I have not been able to test any of it to see if it really is gold or silver yet. Although it does look very promising.

I am also taking pictures of the whole process and will post them as I get further along.


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## rickbb

Oh and when I was looking up ways to pulverize glass, I found out that glass dust is known to cause lung cancer.

Be careful!


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## skyos

I tried already with hot nitric, boiling for 1 hour up, and let cool down all the night, the day after i filter it and put inside some drops of HCl, i can see a light white color appear, and after 1 more day i have a white/ light purple precipitate who become black with NaOH, then add some aldehyde as dextrose, glucose, (not fructose that is a cetone)... The only problem is that this method precipitate differente compounds and i don t really know what ??? because it s not really similar with the silver i have when i process keyboards mylars... :| 

I try also cyanidation but i think i take a too little sample that s why nothing can be observed...

Will try to prepare for this week two solutions of 0.5 M of SC(NH2)2 and H2SO4
and precipitate with Na2S


I just add piture of the 2 kinds of powder I have :






On the left, powder of the first glass, the external one ( no calcination )
On the right, powder of the internal glass after calcination (the white one), and inside the little bag some aluminium from the sticker they put for disperse the heat....


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## skyos

I never think we can find silver inside the external glass, i always believe the silver stay inside the thin white film on the internal glass but.... :



HNO3



AgNO3 / AgCl



AgNO3



AgCl



AgCl



Ag2O



Ag


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## Captobvious

Not sure I understand, is the Silver in the films or the glass? Both? Where is the bulk of it located?


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## skyos

For the external glass , it s stay on the glass, for the internal glass , i m not sure if it s stay inside the white film or just under...


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## rickbb

I have not had the chance to complete my extraction attempts but on the model of plasma I have the silver appears to be printed in thin lines or other wise bonded to the inside of the outer glass of the plasma screen. Over these lines of apparent silver is a clear coating.


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## Evan2468WDWA

skyos said:


> For the external glass , it s stay on the glass, for the internal glass , i m not sure if it s stay inside the white film or just under...


I watched an interesting you tube video recently about lye dissolving glass. Could something like this help with recovering the silver?


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## skyos

Hi Evan,

thank you for this good video from Nurd Rage.

This method should be very effective if you have a few amount of glass and if the PM stay inside the glass.

For the plasma, as rickbb say : the silver looks like to stay top of the glass, not trap inside...

Then, only for my opinion and my case, it will be very difficult to find a big " bucket" that i can heat and process a batch of 100 or 200 kilos of broken glass 

Moreover, the silver is not so expensive so maybe a problem with the cost of the treatment but i m not a professional about this and better i let the true refinner to explain more about this method.

In all the case, thank you for your help and to participate to this thread.

Good luck for you.

Best regards


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