Silver precipitation w Copper

[buckrogers1]

After dissolving Sterling Silver in Nitric Acid, i precipitate the Silver by immersing Copper in the green/blue solution and let it sit obernight
I get a nice silver precipitate that i filter out
two questions:
a) does the silver needs further 'cleaning' with HCL after i rinsed and dried it to clean out possible copper remnants?
b) when do i know all Silver in the solution has precipitated (solutions turns pale blue) shall i add NACL or will this precipitate copper chloride instead?

 

[Yggdrasil]

After dissolving Sterling Silver in Nitric Acid, i precipitate the Silver by immersing Copper in the green/blue solution and let it sit obernight
I get a nice silver precipitate that i filter out
two questions:
a) does the silver needs further 'cleaning' with HCL after i rinsed and dried it to clean out possible copper remnants?
b) when do i know all Silver in the solution has precipitated (solutions turns pale blue) shall i add NACL or will this precipitate copper chloride instead?

If you add any chloride to it, what ever silver is dissolved will precipitate as Silver Chloride.
HCl will not dissolve copper by itself.
But AP will, but I'm not sure it is a good solution for Silver cement.

 

[buckrogers1]

i actually melted some of my precipitated silver powder and to my dismay when i test the bar with the sigma precious metal verifier , i get a reading for sterling silver still. so 92.5 instead of 99 or more. any ideas why?

 

[Yggdrasil]

i actually melted some of my precipitated silver powder and to my dismay when i test the bar with the sigma precious metal verifier , i get a reading for sterling silver still. so 92.5 instead of 99 or more. any ideas why?

What is a sigma precious metal verifier?

 

[Martijn]

i actually melted some of my precipitated silver powder and to my dismay when i test the bar with the sigma precious metal verifier , i get a reading for sterling silver still. so 92.5 instead of 99 or more. any ideas why?

I've read the manual and it delends a lot on how you measure.
Subsurface irregularities in the bar can also cause a misreading.
Surface impurities maybe?
Do you have a picture?
7.5% basemetals for cemented silver is quite impure. Is it rounding the reading off to pure silver or sterling silver?
Like a 'buyers mode' to be on the safe side.

 

[Martijn]

I just Googled it.

 

[buckrogers1]

yes, it's not a perfect bar. i only melted a sample to check the purity. still have the feeling its not 99.9% thou. any suggestions on how to process the silver powder for better melt ? it's a lot over 200 oz so far.

 

[orvi]

Cement from copper precipitation is usually more than 98% pure, if you diluted the solution of AgNO3 with dH2O firstly (best to double the volume of liquid). If not, silver will oxidize copper to copper oxo-hydroxo-nitrates, or whatever is formed on the surface, and this (blackish dust) will fall out of the solution together with silver and gave it greyish black tinge. If this happen, you know purity will be falling below 98 or even 95%.

Endpoint of cementation is best tested with brine solution. Draw a small sample (mL or so) from the solution, and add drop of brine. If milkiness or even white precipitate appear, you still have silver in solution. Agitation is necessary, as the cement will fall to the bottom, it will entrap the silver ladden solution - so above the cement layer, solution could be fairly stripped of silver, but on the bottom, there still could be plenty of Ag in solution. Stir frequently or better use magnetic stirrer (good for no more than few hundreds g of silver, otherwise it will be too hard for magnet to spin around and it gets stuck) or mechanical stirrer.

 

[Martijn]

Submerge the copper completely when cementing.
Stop when it slows down. Decant and get the last bit out in another beaker.
Make sure to use a piece of copper that is thick enough to prevent small pieces of copper from falling off in the cement.
Thouroughly wash with hot distilled water to get all copper nitrate out.
Test the wash water for copper traces in solution with soda or lye in a small beaker.

This way you should be able to get 99% pure.

To get it really pure, use a silver nitrate cell.

 

[buckrogers1]

after various attempts of washing, and drying, even putting the silver cement into a copper sulfate cell (to extract the copper) , cheaper than a silver nitrate cell. The cement got more white . Then i put it into the sun, as a final check, and it's turning slight greenish. i suppose thats copper oxide. Should i use Vinegar and salt to dissolve the copper oxide? or HCL ? I also read that h202 dissolves copper oxide. suggestions please? I do not want to run a silver cell , its too expensive, and too much maintenance if the silver nitrate gets saturated with copper

 

[cejohnsonsr1]

You’re never going to get all the copper impurities out of your silver mud by any form of rinsing. The electrolytic silver cell is probably the least expensive, most efficient method of removing the last remnants of copper and other impurities from silver. The electrolyte will most certainly get saturated with copper. That’s part of its function and an indicator that your cell is actually working. But too much maintenance? If you’re processing enough silver to justify needing to worry about getting from 99 to 999+ then there’s going to be some kind of “maintenance” involved. Refreshing your electrolyte every 10 days or so isn’t really labor intensive.

 

[buckrogers1]

You’re never going to get all the copper impurities out of your silver mud by any form of rinsing. The electrolytic silver cell is probably the least expensive, most efficient method of removing the last remnants of copper and other impurities from silver. The electrolyte will most certainly get saturated with copper. That’s part of its function and an indicator that your cell is actually working. But too much maintenance? If you’re processing enough silver to justify needing to worry about getting from 99 to 999+ then there’s going to be some kind of “maintenance” involved. Refreshing your electrolyte every 10 days or so isn’t really labor intensive.

you're right, i tried boiling in acetic acid, then rinsing, boiling again in distilled water, rinse and dry. i still see copper oxide forming if i expose the silver powder to the sun.
Question, can i do a silver cell with the powder, or do i have to melt it into shot ? What concentration Silver Nitrate do u recommend ? shall i do it myself dissolving pure silver ? how many ounces in how much 70% nitiric ? dilute?
I have a total of 200 Oz of silver powder to process. Have to build a big cell, probably using a Stainless steel pot, and a vacuum bag as holder for powder on the Anode with a Platinum Anode. The Stainless steel pot as Cathode. Am i on the right path? Current 6V 1A , how long do u think it will take me to precipitate all the silver crystals? Will i need to replace the Silver Nitrate every X hours? Do u think i can process that much of Silver at once ? or shall i build a smaller "rig" and process multiple times?
Sorry for the many questions, but i tried a silver cell once and it was a complete mess, everything went wrong.
Copper Sulfate cells are easy by comparison. Appreciate your input .

 

[Yggdrasil]

you're right, i tried boiling in acetic acid, then rinsing, boiling again in distilled water, rinse and dry. i still see copper oxide forming if i expose the silver powder to the sun.
Question, can i do a silver cell with the powder, or do i have to melt it into shot ? What concentration Silver Nitrate do u recommend ? shall i do it myself dissolving pure silver ? how many ounces in how much 70% nitiric ? dilute?
I have a total of 200 Oz of silver powder to process. Have to build a big cell, probably using a Stainless steel pot, and a vacuum bag as holder for powder on the Anode with a Platinum Anode. The Stainless steel pot as Cathode. Am i on the right path? Current 6V 1A , how long do u think it will take me to precipitate all the silver crystals? Will i need to replace the Silver Nitrate every X hours? Do u think i can process that much of Silver at once ? or shall i build a smaller "rig" and process multiple times?
Sorry for the many questions, but i tried a silver cell once and it was a complete mess, everything went wrong.
Copper Sulfate cells are easy by comparison. Appreciate your input .

Do not use text lingo in here, it don't translate well for the ones that rely on translators.

Next this is one of many heavy discussed topics in this forum, so all information needed is here, just search it and start reading.
Starting up a Silver Cell is not something you do tomorrow, it needs preparation and the time spent researching will pay dividends later.
Sreetips and more members on youtube has some good videos I believe.

 

[buckrogers1]

Do not use text lingo in here, it don't translate well for the ones that rely on translators.

Next this is one of many heavy discussed topics in this forum, so all information needed is here, just search it and start reading.
Starting up a Silver Cell is not something you do tomorrow, it needs preparation and the time spent researching will pay dividends later.
Sreetips and more members on youtube has some good videos I believe.

Sorry forgot this is read internationally. Yes you are right there is plenty of information in here. i will do the proper research. It is indeed not an easy task to run a silver cell. Dissolving sterling in Acid is easy.. but the follow up to get to 99.99% is not that easy. I am also looking for someone to melt my powder once i am done into perfect bars, i have an electric furnace, but once i have over 500 oz of silver it will too much for it to process and also it does not create perfect bars. There are always creases or bulges, any recommendation who in here does process smelting at a professional level in the US? Thank again for replying.

 

[cejohnsonsr1]

Sreetips has gone through the entire process of operating a silver cell a couple of times in the past year or so. That’s where I would start my research.

 

[niks neims]

But AP will, but I'm not sure it is a good solution for Silver cement.

Didn't work for me. Lots of silver chloride formed. Tried to melt as is, big mess...

 

[Yggdrasil]

Didn't work for me. Lots of silver chloride formed. Tried to melt as is, big mess...

You need to use Sodium Carbonate or Bicarbonate as Flux, I have not done it myself so I can't remember which.
It is in the forum though, search for smelting Silver Chloride.

 

[niks neims]

You need to use Sodium Carbonate or Bicarbonate as Flux, I have not done it myself so I can't remember which.
It is in the forum though, search for smelting Silver Chloride.

Thanks, I'll keep that in mind and look it up if need be in future.

the point remains:

Don't put your finely divided silver cement in AP (or HCl) unless you want to contaminate it with lots of silver chloride...

 

[Yggdrasil]

Thanks, I'll keep that in mind and look it up if need be in future.

the point remains:

Don't put your finely divided silver cement in AP (or HCl) unless you want to contaminate it with lots of silver chloride...

That is why I said that I didn't know if it would play well, it will take the copper eventually, but as you said also contaminate the Silver.

 

[buckrogers1]

i started a silver cell following streetips videos, is working fine, pieces of silver are falling off beautifully shining, i just have one problem , after a day my electrolyte is no longer clear but a bit milky and light blue (which i guess is coming from the copper slowly going into the solution ) it's the milky non transparent color that mystifies me. Then i checked my water , and noticed that instead of distilled water , i was delivered purified water. Is that the issue? Purified water contains contaminants? Shall i filter the electrolyte and start again, or just leave it and at the end when the electrolyte is really saturated with copper, precipitate the remaining silver with a copper bar and restart with a fresh batch of new electrolyte?