Some problems in my first experience ( Dissolve silver in nitric acid )

[saadat68]

Tap water is fine.

Hi Palladium. I think just you can help me
In fifth experience I had a good leaching and cementation. I thought I learn leching step but I produce some silver chloride again!!!!
http://uupload.ir/files/serg_img_20171021_173340.jpg

I just used tap water in washing step. My process:
Wash 100 powder with tap water
decant
Drying (100 gr powder with maybe 0.5 liter tap water )
Go for leaching after 2 days
These residue don't dissolve in nitric. I test them twice
http://uupload.ir/files/scpr_img_20171021_204205.jpg
I am really confuse. How these silver chlorides produce? From what?
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I really want to go out from this business but I can't also I don't think can find sterling silver for refining

 

[Topher_osAUrus]

Tap water has chlorides in it
Any chlorides plus AgNO3 = AgCl

Whether its during your dissolve, during your wash, or whatever -the chlorides from the tap water will make insoluble chloride.
-That is your delimma.

And, anyone can find sterling or gold. Its everywhere. You just need to find the right person or people to buy from or refine for. But, before working on other peoples material. I highly suggest first becoming proficient in the standard processes.

 

[saadat68]

Thanks Topher
I still have a little powder. I will use distill water in washing step :?

But when I added powders to nitric they are completely dry!

Maybe they are MnO2 :shock:
Edit: I think all of these days I deal with MnO2 not silver chloride
I don't like refine gold because I must start learning from first
I will investigate some about silver sterling but I am not optimist

 

[Topher_osAUrus]

Thanks Topher
I still have a little powder. I will use distill water in washing step :?

But when I added powders to nitric they are completely dry!


I don't like refine gold because I must start learning from first
I will investigate some about silver sterling but I am not optimist

I need some clarity.
You dissolved the powders initially, then cemented, then washed with tap water. Made some silver chloride, that you then dried and tried dissolving again?
May I ask why?

There is a couple things you could have done and actually got the silver done and melted by now instead of starting all the way back at step 1.

Palladium has been busy lately, and I dont know if he will even see this. So I can try to help you.
-1; you could have just melted the silver with the little bit of chloride in the mix, just using soda ash flux in addition to borax (not the best idea, as the fumes are absolutely terrible, and there will be losses)
-2, dissolve the silver chloride from the silver cement with ammonia hydroxide (immediately acidify the diammine silver chloride complex, never let it sit and dry, it can and will go boom)
-3; a quick wash with sodium hydroxide would have converted the chloride to oxide, which could have been washed, dried, and melted with there being no consequence to the metallic silver cement. (Thats probably the best option Id say)

Tap water can be used to wash your silver cement, but (this is a big but here), your silver must all be cemented out of the nitrate solution. Otherwise, well, its obvious now I'm sure, but -silver chloride- happens.

Since you have dissolved it all again, just filter off the silver chloride. Then cement out the silver and after its all out of solution, start rinsing and washing and cleaning it up. That chloride on the filter is going to be harder to convert now since it has dried. It's undergone a change in the crystal structure and what not, so I would just put it back for later down the road after you have gotten accustomed to the standard reactions.

Personally, I think gold is much easier to refine than silver. Its much more forgiving, at least. So long as you follow common practice, i mean.

Edit to finish -oops-

 

[saadat68]

Thanks for your helping
No, After crushing I wash batteries with tap water to remove electrolyte (Potassium hydroxide) and some zinc
Decant and let them to dry and then add nitric >>> filter
Residue is from this step. They don't dissolve in nitric

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=25632#p272761

I still have a little batteries. I will wash them with distilled water and then add nitric if I have residue that don't dissolve in nitric so they are MnO2

 

[saadat68]

sound like they are MnO2 not silver chloride
I dissolved a little powder today without washing. Just used distill water. I had residue again. They are black
I must have 130 to 150 gram cemented silver. After cementation I will weigh cements and if they are 130 gram or more so I didn't loss silver as AgCl
http://uupload.ir/files/8hmj_img_20171022_193809.jpg

 

[Topher_osAUrus]

Silver chloride turns black in sunlight, but can revert back to white if covered from sunlight for long enough.

Carefully dry your cement until it is just moist powder, then turn up the heat. Bring it to a dull red heat with a torch, but do not melt it (this should be done in a corningware pyroceram dish or stainless pan)
You will see some red NO2 gas coming off (its impossible to rinse 100% of it out) and the silver will lose some volume (shrink a bit). After it cools, then weigh it. It will be a pretty close weight to what you will have after melt (assuming there is no silver chloride and you dont have substantial melt losses)

Again, if you are worried those MnO2 powders having some silver chloride mixed in, there are a couple methods you can use to dissolve the AgCl away from the MnO2. I mentioned one earlier, maybe both, I dont remember, as this thread is epic in length.
Ammonia hydroxide or sodium thiosulfate can each do it.
-personally, I would just keep that black ball of whatever it is moist and worry about it later, focusing on recovering the silver cement.

 

[g_axelsson]

Is there any MnO₂ in silver oxide batteries? Nothing I can find would support that.
Then the starting material wasn't sorted well.

I don't have time right now to try to refine my silver oxide batteries. It has to wait until later, so if I'm wrong just let me know.

Göran

 

[saadat68]

Thanks. Got it
Residues were black from first and don't turn to black also I don't have sunlight in my workshop.
I am not worry about mixing silver chloride in residue. If they are silver chloride I prefer to add them to trash!!!
I just worry about next process. I want leach my batteries without any problem especially without producing AgCl in sixth experience.

g_axelsson
Is there any MnO2 in silver oxide batteries? No
http://uupload.ir/files/ilze_untitled_-_2.jpg

I sorted them but yes they had a little alkaline cells
My residue are high so I am suspicious.

 

[g_axelsson]

I still think you should do some tests with known silver to learn the chemistry or you will never recognize what is happening.

Göran

 

[saadat68]

If I could get silver sterling here I switch to sterling!
If this residue be just MnO2 and my cements be minimum 130 gram I think I learn leaching step

 

[autumnwillow]

Hi, I have a question
Can I use this process for silver oxide batteries ?
- Crush and wash
- Mercury distillation
- Leach powders with dilute HCl to remove zinc and impurities
- Melt with some soda ash
- Run to silver cell and melt again

Method 1:
1 - Crush and wash
2 - Mercury distillation
3 - Digest in nitric (Silver and other base metals will dissolve)
4 - Filter
5 - Add hcl in filtrate (Sliver will precipitate as silver chloride)
6 - Filter
7 - Wash residue until pH is equal to wash water (Pour all in a filter paper to save wash overs)
8 - Put filter paper from step 7 and residue from step 7 in a bucket, add 10% sulfuric and iron nails, mix with pvc pipe until it looks like sand.
9 - Wash until pH is equal to wash water (Pour all in a filter paper to save wash overs)
10 - Dry and melt.

Result from this method should yield 99% silver. Who are your buyers? What is their requirement? If they need 99.99% put in a silver cell.

Method 2:
1 - Crush and wash
2 - Mercury distillation
3 - Digest in nitric (Silver and other base metals will dissolve)
4 - Filter
5 - Cement with copper
6 - Filter
7 - Wash residue until pH is equal to wash water (Pour all in a filter paper to save wash overs)
8 - Dry and melt.

Result from this method should be about 95-99% depending on the form of copper you used. Wires will contaminate it more, a large bus bar is better. Proceed with silver cell if higher purity is required.

There is another method which is shorter but since you have mercury in your lot I suggest not doing it as small contamination of such could be deadly.

Although method 1 takes more time, it is actually cheaper and you don't have to worry about silver chlorides because you are making them anyway. Iron is relatively cheaper compared to copper. Sulfuric acid used here is reusable. Your waste from hcl/nitric can be re-used or treated for disposal.

 

[saadat68]

There is another method which is shorter but since you have mercury in your lot I suggest not doing it as small contamination of such could be deadly.

Thanks
Can you explain other method ?

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My cements are little. I don't know I lost silvers or silver oxide batteries were fewer than I calculated
My batteries were 350 gram
Maybe I had 50 gram MnO2 battries that I could not separate
300 gram X 30% = 90 gram
Maybe I have 10 gram silver in filter papers and crusher
So I must have 80 gram silver cement in worst condition
I get 45 gram!!!!

I must say I lost. I accept it
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Edit:
I buy some batteries and want to try again
This is my last try!

 

[saadat68]

Because you advice me to refine gold or silver sterling I researched some about them
Gold: Price is on the spot or sometimes high! Also selling gold shots/ingots is very hard and I must get assay and have license...
Silver: Price is 85% of spot but I can not find enough sterling. Competition is very high and sellers prefer sell them to jewelry makers.
So only choice is button cells and maybe electronic scraps. Both of them have toxic metals
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Today I refined one kilo silver oxide batteries. My returns was 22%. It is low but very better than last experiment. Now I must distill Hg. I really afraid do it. I don't like do this in my small workshop!!! Topher said me before about that.
I will try distill Hg and melt it but I want to test chloride method that juan explained before. Maybe I will get better returns and remove Hg with wet method.

Thank you

 

[tortuga09]

Good evening
Every country has these rules and law on these precious metals
In Iran as in France there are laws
It's up to you to see how worked and what product