White grey precipitate in silver nitrate that’s not silver chloride

[Gsracer]

Hey grf

So I processed about 250 grams of marked sterling Gorham flat ware in nitric. No knife handles. I needed to let the solution sit for a while as I had other things to do. So I added a couple 100 ml of distilled water to dilute it and got a cloudy white gray precipitate

Now I know that it’s not chlorine in my distilled water making silver chloride because the silver cell electrolyte on the left of the picture was made from the same gallon. Also Just for good measure I added a splash of the distilled water to the cell and got no precipitate so the water is good.

I think it’s something in the batch of silver.


Now its worth noting that this has happened to me on a few occasions. Normally I just let the precipitate settle and filter and recover my silver with copper as normal.

However I was curious as to what it could be. I think it has something to do with the solubility is decreased based off of temperature. As if I heat it some precipitate goes back into solution but i dont heat it alot just gentle heating.

Any idea what it could be? Perhaps zinc?

Pictures of the precipitate


I tj

 

[Geo]

Allow it to settle completely and decant the solution from the solids as best you can. You will have to filter the last bit. After collecting the solids, you can do some testing. Place some of the solids in a small container and add a little HCl. Add chlorine bleach by the drop. Just a couple of drops should work for a third of what I see in the beaker. Let it sit undisturbed for about an hour. Test the resulting solution with stannous chloride. If there is no positive test result, it may be carbon or some other non-reactive material. No positive test = trash.

 

[Gsracer]

Thank you Geo. I get what your saying.

I took a gram or two from the filter and added hcl. I didn’t have bleach so I added 1ml of nitric and let it sit.

I’m going to grab some tin later to make some stannous so I can laugh at this yellow gold looking solution.

 

[PeterM]

Hey grf

So I processed about 250 grams of marked sterling Gorham flat ware in nitric. No knife handles. I needed to let the solution sit for a while as I had other things to do. So I added a couple 100 ml of distilled water to dilute it and got a cloudy white gray precipitate

Now I know that it’s not chlorine in my distilled water making silver chloride because the silver cell electrolyte on the left of the picture was made from the same gallon. Also Just for good measure I added a splash of the distilled water to the cell and got no precipitate so the water is good.

I think it’s something in the batch of silver.
View attachment 49355

Now its worth noting that this has happened to me on a few occasions. Normally I just let the precipitate settle and filter and recover my silver with copper as normal.

However I was curious as to what it could be. I think it has something to do with the solubility is decreased based off of temperature. As if I heat it some precipitate goes back into solution but i dont heat it alot just gentle heating.

Any idea what it could be? Perhaps zinc?

Pictures of the precipitate

View attachment 49356
I tj

Zinc it out, filter, wash dry. Wrap in silver free lead and cupel. Then part in 20% HNO3 with light heat, any blacks remaining will be gold or better.

 

[orvi]

Thank you Geo. I get what your saying.

I took a gram or two from the filter and added hcl. I didn’t have bleach so I added 1ml of nitric and let it sit.

I’m going to grab some tin later to make some stannous so I can laugh at this yellow gold looking solution.

As Geo said, stannous test is very important. A lot of times, there could be just some insoluble junk, but judging by the colour, there could be something more interesting Stannous will tell you.
If it is something of value, give it slightly more nitric (to be sure) and boil it briefly. If gold, go as normal (denox, dilute with ice, filter, drop the gold with SMB).

It well could be some other thing than gold or other PMs, but I think it isn´t iron (judging by the colour).

Tell us how it went.

 

[Gsracer]

Well the verdict is in, tested a drop of the yellow solution on a filter paper.

When the fresh stannous solution hit the drop it went from yellow to completly clear. Never seen that result before but in line with what i guess we all expected. Some insoluble junk.

Thank you all.

 

[orvi]

Well the verdict is in, tested a drop of the yellow solution on a filter paper.

When the fresh stannous solution hit the drop it went from yellow to completly clear. Never seen that result before but in line with what i guess we all expected. Some insoluble junk.

Thank you all.

Ferric ions could be reduced with stannous to ferrous ions. These are very faintly coloured in comparison to ferric. So this could explain the behavior perhaps. I also encountered similar behavior before. But gold is unmistakeable.

That said, I wasn´t right. It was probably only iron in solution