Not all gold gold dropping from AR

[acolvin4]

Ran my First batch of fingers from computer boards and RAM sticks. I used the Ap Method and washed my fingures clean. I dissolved the clean fingures in heated AR solution (was yellow and not green). Then I added Smb to the solution and let settle over night. Now some of the gold precipitated to the bottom and i tested the solution with stannous chloride and and i am getting heavy positive on the q tip. Could there still be excess nitric in the soulution or what???? im lost here

 

[Palladium]

Do you have any urea?

 

[acolvin4]

i don't have urea. but i can get some. i never bought any because most of the threads i've read on here don't use it. Would urea help?

 

[Palladium]

You could take a prill of urea and drop it into some solution you pulled out for a test. If the urea fizzes then you have free nitric in solution. You said you have gold on the bottom of the beaker so that tells me you should have the free nitric eliminated or the gold would go back into solution. Maybe some did go back into solution and now it has achieved a balance with the excess nitric. Have you tried adding a little more smb?

 

[acolvin4]

I did add a little more smb and retested with stannous and the reaction took a little bit longer on the q tip but still showing a presence of gold

 

[Dr. Poe]

The urea test/reaction for nitric works best above 160F. Dr. Poe