opinions please.

[artart47]

Hi Friends!
I'm testing some bags of concentrates that I received from another forum member. He say's that he processed gold plated boards in a nitric solution and was recovering the foils. Somehow, much of the foils went into solution. next, he evaporated the solution to powder, dried the powder and then brought the powder to red heat.
I hope he didn't do what I'm afraid he did!
I did some small tests on three gram sample of a bag with black powder.
(a) leached the powder with HCl, dissolved about 90% of the sample and gave the familiar emerald green copper chloride
(b) Rinsed with H2O/heat, HCl again with heat. solution is clear, remaining dark, brown powder was unaffected.
(c) leached the powder with HCl/chlorox. Powder unaffected. Tested his solutions and my gold chloride solution with newly made stannous chloride.
Stannous is good, his material is negative for gold.
I was afraid from the start that he may of burned off the goldchloride during the incineration or the evaporation.
I'm going to continue testing small samples of the other bags. and searching for posts on that subject. Another scan of Hoke.
I'd like to hear any referral or advise.
Thanks!
artart47

 

[4metals]

Incinerating a salt can cause it to go up in smoke. True with all of the precious metal salts. You want to reduce the salts to a metal before incinerating. Salts can be reduced with heat but it is called calcination and it involves slow stepping up of the heat in increments to drive off the halogen.

 

[artart47]

Thank you!
I remembered reading about slowly heating metal salts to reduce them to metals but wasn't having much luck with my search terms.
I'm going to run small samples from the other bags of powder and test for gold.
Thanks again.
artart47