# Tin mixed in silver.



## conglioa (Aug 31, 2020)

Hi guys - sorry this is the 2nd time I've asked you about this.
I recovered silver from copper anode anode lubricant by AgCl precipitation method and reduced with zinc in HCl medium.
I was told that this method will give quite pure silver but I did it very carefully many times and reanalyzed by spectrophotometer the results were not different.
Can you advise me on which method can selectively precipitate Ag without dragging Sn so that I can obtain Ag with minimum purity 99.0% without silver electrolyte.
Thank you.


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## nickvc (Aug 31, 2020)

One source of your problem could be not rinsing your silver well enough once converted.
But the best advice would be to run your silver through a silver cell once melted that will produce 999 silver if run correctly, it’s also a cheap way to attain the quality you are looking for.


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## Owltech (Aug 31, 2020)

Reduction with formate from silver nitrate.


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## conglioa (Aug 31, 2020)

nickvc said:


> One source of your problem could be not rinsing your silver well enough once converted.
> But the best advice would be to run your silver through a silver cell once melted that will produce 999 silver if run correctly, it’s also a cheap way to attain the quality you are looking for.



Thank you.
I've also been thinking about electrolysis to get 999 silver, I would be happy and appreciate if you have experience can share with me the necessary parameters so I can design a secure system. Technical requirements such as:
- Anode current density, cathode current density.
- What is the optimal silver content in the electrolyte solution g / l.
I need some information to be able to design the system to suit my needs.


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## conglioa (Aug 31, 2020)

Owltech said:


> Reduction with formate from silver nitrate.



Could you please give me more details?


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## rickbb (Aug 31, 2020)

Rinse the AgCl better, time spent here will be time well spent. Seriously, even if you think it's clean, rinse again. Water is the cheapest chemical you will ever use.

I would use either iron\dilute sulfuric acid, or sugar\lye method to convert AgCl to silver metal. I never got decent results using zinc.


Edit to correct grammar.


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## conglioa (Aug 31, 2020)

rickbb said:


> Rinse the AgCl better, time spent here will be time well spent. Seriously, even if you think it's clean, rinse again. Water is the cheapest chemical you will ever use.
> 
> I would use either iron\dilute sulfuric acid, or sugar\lye method to convert AgCl to silver metal. I never got decent results using zinc.
> 
> ...



Maybe I wash AgCl not clean enough, I need more meticulousness to reassess. I have never used iron / sulfuric acid nor reduced with sugar solution. Chances are I will try all the methods to find the most effective solution.


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## Palladium (Aug 31, 2020)

What is the original materials metallic composition?


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## conglioa (Aug 31, 2020)

Palladium said:


> What is the original materials metallic composition?



My raw material is anode sludge of copper electrolysis.
The main impurity composition includes Cu, Pb, and Sn.
After processing the silver cup, only Sn remained in Silver and I was having a headache with it


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## Palladium (Sep 1, 2020)

Try this. After you have washed the slimes with water to remove any residual, i'm assuming sulfuric acid, take a small sample and heat it using only hcl. Give it about an hour on heat and then let it cool. After it has cooled wash several times with water to remove any residual hcl. Melt a sample and see what the analysis is. From there you should be able to move on to another step in the process using the method of your choosing. 
Lets see what the numbers look like after the hcl step.


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## Lou (Sep 1, 2020)

You can always try melting the slimes (if free of PGM) with nitre and soda ash and a little borax glass.

I know that cleans the lead/tin/copper/zinc out of silver slimes.


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## conglioa (Sep 3, 2020)

Lou said:


> You can always try melting the slimes (if free of PGM) with nitre and soda ash and a little borax glass.
> 
> I know that cleans the lead/tin/copper/zinc out of silver slimes.



Many thanks for your advice. I have a bit of a problem to ask for advice. I have considered using a silver electrolysis tank and I calculated some parameters like this:
- Anode size: 28 * 28 * 2 (cm)
- Titanium cathode size: 30 * 30 * 0.5 (cm)
- Cathode current density: 400-500 A / m2
- The distance of each pair of anode: 7 cm
Number of anodes (cast in 97% silver): 10
Number of titanium cathodes: 9
- Yin and Yang see alternating
- Concentration of Ag in solution: 100 g / l
Free HNO3 concentration: 1-10 g / l
- A little more copper about 0.5 g / l
As such I would have to give the system a power supply of around 650A to achieve a current density of 400A / m2.
I calculate the mass of each silver anode will be about 16.5kg, the number of silver I have is about 500kg. Each batch will electrolysis 165kg, so will have to conduct 3 batches.
With the above parameters, if there is any error, please help me so I can proceed in the most favorable way, thank you very much.


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## conglioa (Sep 3, 2020)

Palladium said:


> Try this. After you have washed the slimes with water to remove any residual, i'm assuming sulfuric acid, take a small sample and heat it using only hcl. Give it about an hour on heat and then let it cool. After it has cooled wash several times with water to remove any residual hcl. Melt a sample and see what the analysis is. From there you should be able to move on to another step in the process using the method of your choosing.
> Lets see what the numbers look like after the hcl step.



I tried a small amount of sample with HCl your way and it was too hard to wash it off. The remaining solids are too fine to make filtration difficult and I was unable to wash off the HCl. I tried to dry the sludge after reacting with HCl and proceeding by my method of choice heating it with concentrated H2SO4, and as a result, the silver obtained was not as expected (less than the test samples. different from the same volume you started). I think a part of Ag has been converted to AgCl and mixed in the residue after filtration. I know if I can wash off the HCl it will be easier but it doesn't seem to be favorable for me to have it washed off.


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## Martijn (Sep 3, 2020)

Have you read this thread? 
https://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=17233
All you need to know is discussed there. And it works like a charm.


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## Junior Miner (Sep 6, 2020)

Thanks everyone, I was looking for a way to refine silver without the use of too many heavy chems. 

This dude here shows how to do it ( very slow&rather boring, yet it does place emphasis on the importance of preparing well. I don't know if that space he's using is well vented, though) 

[youtube]https://www.youtube.com/watch?v=5iyo_FPoeto[/youtube]

[youtube]https://www.youtube.com/watch?v=dKCkrIB3vC8[/youtube]
this gent uses nitric acid along with borax. It's all very visual. 

the #silverrecovery hashtag leads to more videos of the same type. Useful info, yep.


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## g_axelsson (Sep 8, 2020)

Somehow I doubt the numbers are correct. Lead free solder contains about 2-3% silver if any, there are many lead free alloys that lacks silver. So to get a button of 3.6g you need to dissolve more then 100g of solder alone and I don't think BGA:s are made from 40% solder.

Then to dissolve the silver you need to dissolve all the copper in the BGA fiber boards or the copper will start cementing the silver inside the fiber boards. And that would be around 20-30% of the mass. So the amount of acid you need to dissolve 250g of CPU:s is probably around 100-200 ml at least. Diluted 50% and we get 200-400 ml of liquid.

As a source of silver, BGA flip-chip is probably quite bad. All that tin is turned into metastannic acid so the silver nitrate will be quite hard to wash out of it.

The video is showing a quick and smooth process without showing the whole picture or mentioning all the pitfalls along the way.

Just saying...

Göran


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## conglioa (Sep 8, 2020)

I would like to share a little bit about the results of my silver electrolysis.
After finding ways to clean 97% silver without the use of electrolysis I was not successful.
Then I electrolytic a small amount of silver and the results are very good. I sent the sample to a gold-silver store and it got 99.99%. There was an amount of 80ppm of copper that I was not careful with so it melted a little of the copper I used as a wire when connecting the silver anode to the solution. Because my silver anode has absolutely no copper before. If I'm more careful, can I get 99.999%? I'm just asking because I know 99.99% is more than enough.


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## Lou (Sep 8, 2020)

That’s the way to go!! Very good work.

Your data looks right. You don’t need to use a titanium cathode (stainless can work) but it is the best.


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## conglioa (Sep 8, 2020)

Lou said:


> That’s the way to go!! Very good work.
> 
> Your data looks right. You don’t need to use a titanium cathode (stainless can work) but it is the best.



Thank you very much. I had a lot of experience in electrolysis of copper refining on an industrial scale, but with silver it was completely new. I have to consult a lot of documentation on the specs for silver electrolytic silver to build my own system. With that little experiment I thought it was the best way to get the highest levels of silver. I have all the equipment needed to build a system with a capacity of about 50 - 100 kg / day. When it comes to making it work, I will share it with you. I do not know what will happen when doing large scale but I am always ready to face and it is also a chance to gain experience in the work.


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