Needle like crystals in silver nitrate

[Yggdrasil]

Okay excellent thank you.

Unfortunately there is definitely lead. See video. It appears that it will be a factor in silver recovery.

I like the prospect of adding sulfuric acid to the nitrate solution because of the very obvious precipitate which can easily be filtered. Seems like the best way.

However I could also add HCl and convert lead and silver nitrates to chlorides and wash with boiling water. But how would I know if I got all the lead sulfate dissolved?

Does anyone have a strong opinion about which method is best regarding purity? I'm definitely leaning towards sulfuric acid method.

Assuming I go with sulfuric method, after adding sulfuric drop wise I should mix it right? And stop adding drops when no more precipitate forms?

Otherwise, I think the inquarted gold turned out nicely, and as a bonus the 2 tiny diamonds from my grandfather's wedding band made it through unscathed. I cannot believe that!

Thanks again for your help! Vinny

Lead sulfate will not dissolve, that is why we add Sulfuric acid to the solution.
If you add HCl, Silver will drop as Silver Chloride and the Lead Chloride will for the most part still be in solution.
Depending on temperature and concentration.
Not a good solution.

And yes, add until no more precipitate forms.

Are you sure there are no Chlorides in the Sulfuric you added?
It is way to much "Lead Sulfate" forming, to me it looked like Silver Chloride.

And the Gold looks fine, maybe a tad dark, there might be a bit contamination left.
Refine it and it will be perfect, the parting after inquarting is just a recovery step, so it is not yet refined.

 

[Vinny PaisAuno]

Are you sure there are no Chlorides in the Sulfuric you added?
It is way to much "Lead Sulfate" forming, to me it looked like Silver Chloride.

I know that's why I'm so worried because it seems like A LOT of lead!

The sulfuric I added to the nitrate solution was concentrated Zep brand drain cleaner which the MSDS indicates is at least 90% sulfuric acid.

I introduced no halides of any kind unless they were in the sulfuric acid.(doubtful) Its precipitate looked very much like table salt.

In a different test tube I added HCl and the precipitate was very different looking. It was fluffy and chunky and turned gray in light.

Tomorrow I will again add some sulfuric acid to a small sample of nitrate solution, then add some HCl to the filtered supernatant and see what happens.

If there is indeed that much lead, I am starting to suspect I was sold some fake silver rounds. Or the gold was alloyed with mostly lead. Neither of those seem probable.

Thanks again, Vinny

 

[Yggdrasil]

I know that's why I'm so worried because it seems like A LOT of lead!

The sulfuric I added to the nitrate solution was concentrated Zep brand drain cleaner which the MSDS indicates is at least 90% sulfuric acid.

I introduced no halides of any kind unless they were in the sulfuric acid.(doubtful) Its precipitate looked very much like table salt.

In a different test tube I added HCl and the precipitate was very different looking. It was fluffy and chunky and turned gray in light.

Tomorrow I will again add some sulfuric acid to a small sample of nitrate solution, then add some HCl to the filtered supernatant and see what happens.

If there is indeed that much lead, I am starting to suspect I was sold some fake silver rounds. Or the gold was alloyed with mostly lead. Neither of those seem probable.

Thanks again, Vinny

Think through what you dissolved, and see if you can find the source there?

 

[Vinny PaisAuno]

Hi friends, I believe I've made some errors here, which came from some invalid assumptions. 1. I assumed there was lead (maybe not) 2. I assumed adding sulfuric acid would ONLY precipitate lead sulfate (false it will also precipitate silver sulfate).

Yggdrasil, your intuition I think was correct in saying it was too much precipitate to be lead, and that it looked like silver chloride. In the end I think the precipitate was silver sulfate. I believe this because it is somewhat soluble in hot water. Lead sulfate does not dissolve at all.

In the end, I'm very glad I didn't add sulfuric to the whole batch because if it WAS lead, I would then have silver and lead sulfate mixed together with no way to separate the two.

Well maybe that's not entirely true either, I could add NaCl or HCl and convert to chlorides and wash with copious amounts of boiling water which should dissolve the lead chloride.

Going forward, to recover the silver I think it will be best to leave sulfuric acid out of the equation, and convert the silver to chloride, then wash in copious boiling water and go from there.

Am I missing anything?

Here is a picture. To the test tube on the right I added concentrated sulfuric acid and dropped what I believe to be silver sulfate. (Originally thought was lead) Then I decanted the supernatant and placed in the left tube. To that I added HCl which precipitated what I believe to be silver chloride.

Still, in the right test tube, I couldn't understand why all the silver nitrate didn't convert to silver sulfate and there was some silver left to precipitate as silver chloride in the left tube. What I think happened was the first drop precipitated silver sulfate, but additional drops actually started dissolving the silver sulfate back in to solution . That solution was still pregnant with silver nitrate and dissolved silver sulfate which readily converted to AgCl with addition of HCl.

Anyway I'm sorry for the confusion and hope I didn't lead anyone down the wrong path!

Incidentally I am still wondering what the gel is in the nitrate solution, and am starting to suspect metastannic acid!

Thanks again for all your help, Vinny

 

[Yggdrasil]

Hi friends, I believe I've made some errors here, which came from some invalid assumptions. 1. I assumed there was lead (maybe not) 2. I assumed adding sulfuric acid would ONLY precipitate lead sulfate (false it will also precipitate silver sulfate).

Yggdrasil, your intuition I think was correct in saying it was too much precipitate to be lead, and that it looked like silver chloride. In the end I think the precipitate was silver sulfate. I believe this because it is somewhat soluble in hot water. Lead sulfate does not dissolve at all.

In the end, I'm very glad I didn't add sulfuric to the whole batch because if it WAS lead, I would then have silver and lead sulfate mixed together with no way to separate the two.

Well maybe that's not entirely true either, I could add NaCl or HCl and convert to chlorides and wash with copious amounts of boiling water which should dissolve the lead chloride.

Going forward, to recover the silver I think it will be best to leave sulfuric acid out of the equation, and convert the silver to chloride, then wash in copious boiling water and go from there.

Am I missing anything?

Here is a picture. To the test tube on the right I added concentrated sulfuric acid and dropped what I believe to be silver sulfate. (Originally thought was lead) Then I decanted the supernatant and placed in the left tube. To that I added HCl which precipitated what I believe to be silver chloride.

Still, in the right test tube, I couldn't understand why all the silver nitrate didn't convert to silver sulfate and there was some silver left to precipitate as silver chloride in the left tube. What I think happened was the first drop precipitated silver sulfate, but additional drops actually started dissolving the silver sulfate back in to solution . That solution was still pregnant with silver nitrate and dissolved silver sulfate which readily converted to AgCl with addition of HCl.

Anyway I'm sorry for the confusion and hope I didn't lead anyone down the wrong path!

Incidentally I am still wondering what the gel is in the nitrate solution, and am starting to suspect metastannic acid!

Thanks again for all your help, Vinny

If the Gold was old maybe there was some Tin in it, I have not heard they used Tin in general Gold alloys but it has been used for brazing and soldering.

 

[kurtak]

I have not had time to fully read this thread however two things

1) The "jell" was likely (though not absolutely) the result of borax

2) Testing for lead --- put a few ml of the silver nitrate in a test tube - add some HCl to precipitate silver chloride (which will also precipitate lead chloride if there is lead in the silver nitrate) expose it to light (any light will do but sun light is best) the silver chloride (on its surface where exposed to the light) will do what is called photo graying (turn purple/black/gray) the lead chloride (if there is any) will not photo gray but stay white

So - if after exposing to light you see white specks/spots that don't photo gray its likely lead chloride

The lead chloride can be removed from the silver chloride by multiple HOT water washes

Kurt

 

[Shark]

Did you use any clasps or latch’s with the material? Often they will be made from other materials and/or have solder on them.

 

[Vinny PaisAuno]

Yes in fact there were several pieces that included clasps, and a couple of very intricate and complicated pieces that were definitely soldered together. I assumed silver solder but definitely not sure now.

Kurt, I'd like to try the sunlight experiment, but as a fellow Pacific Northwester, you know we won't see that until July!

I'm remembering now that the gel seemed to dissolve in hot water fairly well, so that definitely indicates it's not metastannic acid.
I definitely used way to much borax (rookie mistake) when melting for inquartation. I would be interested to hear more about the possibility of this creating a gel like substance in the nitric while parting the 6k gold.

Thanks again for all the replies. Vin