Have you read BFESSERs sticky on Silver?
-Yes... in fact- I LOVE the statement "majority of questions seem to be coming from those who have little to no interest in chemistry, but who
greedily seek wealth through spoon-feeding. As a result, don't expect any mercy. There are plenty of resources out there for those who care not about
the science, but only wish to refine silver for profit. Seek those out, and please spare us the nuisance."
Why am I here? Well I am dealing with a product I did not create- but know the conditions it was created under- and want to understand what I am
dealing with.
I have been given the contents of an etching tank from a small jewelry shop that has closed down. Fellow used this tank for etching silver (sterling
only- no gold) with his variac.
Tank was filled with Ospho (75% phosphoric acid) and DH20. (Per the owner).
The Silver was "electro-etched" and the sludge is a blackish flake.
Am I dealing with a silver phosphate or is the color from the reaction of the Cu to the acid?
I am trying to understand what is IN the tank as a product of the electro chemistry before I go mucking about trying to reclaim any of it.
Hoke and Bedford have no info regarding phosphates of silver in reclaim or purification and the flakes are the wrong color to be true silver phosphate
(in my experience they are yellow orange).
Any thoughts appreciated (applying to this problem) or pointers to the direction I need to head.
Thanks in advance and I hope you guys/gals and folks have a good day!
Silveraga - 23-4-2015 at 13:35
A photo or two would be helpful.blogfast25 - 23-4-2015 at 14:26
The Silver was "electro-etched" and the sludge is a blackish flake.
Try and dissolve some of it in % 50 nitric acid. If it dissolves easily you have elemental silver.aga - 23-4-2015 at 14:36
erm, don't many thing dissolve easily in HNO3 ?DraconicAcid - 23-4-2015 at 14:48
Try dissolving it in ammonia- silver salts will generally dissolve in that. If it turns blue, it's a copper salt. If it doesn't dissolve, then try
the nitric acid.Marvin - 24-4-2015 at 10:20
It's a good bet the sludge is a mix of silver metal, oxide and orthophosphate with other metal salts. If a solution can be made with a small amount
of nitric acid to dissolve the oxide and metal (Toxic fumes!) and then aq strong ammonia, then adding formalin should reduce the silver (and
potentially any other precious metals and copper). IIRC all jewellery silver contains copper, so after the ammonia is added it will probably be deep
blue.
Working with these reagents if the process fails and something more complicated is going on then they can be boiled off (outside) without adding to
the bulk. Some ammonium nitrate would be formed, so you would not want to heat >100C.
