Nitric Blunders

[nicknitro]

Here Begins the topic for Nitric Acid Blunders. Hopefully a newbie will read this and avoid the hours of additional refining time and chemicals involved.

This was the reaction from a solution of nitric/phosphoric acid to dissolve cellphone boards. I filtered the solution and left in a container for a few days, then reused the nitric acid solution to remove some foils from close cut fingers.

It started out great fingers were flowing flakes in solution. Then when I tried to wash the nitric from the filter it immediately formed a blueish gel that was very hard to filter. It finally dried, with the help of Isoprpanol, and I set it aside.

I tried again with the same solution and ended up with a bunch of gold flakes and a very fine white powder.

Show pictures here.

 

[nicknitro]

Pictures of the 2 distinct harvests from the same solution.

 

[nicknitro]

The Left Side Contaminate, I added a quarter cup of HCL 31.45% to break up the stannous, I allowed the solution to fume and sit for a while then I checked the progress of the HCL in dissolving the metals. I added more HCL to the solution as the tin had not completely dissolved, and that did the trick.

 

[nicknitro]

I was scared of the gold going into solution, as I did not incinerate, and the HCL turned very yellow in solution, but, the gold flake remained, and pon test with a descent stannous chloride solution, my q-tip remained yellow. Nothing in solution.


Waiting for more info.

Thanks,
Nick

 

[arthur kierski]

just a thought---if you make a test for gold with stanous chloride in a stanous chloride solution,gold(if exists) precipitate will not come down---the stanous chloride solution already precipitated all the gold when you heated stanic acid with hcl----i would try zn powder or some cu to see what happens---as i said/
just a thought---by the way :did you dissolve the board with nitric+phosforic?

 

[nicknitro]

Arthur,

The test with stannous was for the filtered solution to see if I had dissolved any of the gold flakes with the HCL added to an unknown amount of nitrates still included with the old filter I had filtered the finger/nitric acid solution. Basically I was not trying to dissolve any gold at all. Do you see?

In both experiences, the first "blunder" of trying to use nitric to remove the gold foils from populated cell phone boards, which I was trying to show is a very poor way to process these boards, I did use the nitric/phosphoric acid.

In the second "blunder" I tried to re-use the nitric from that solution, figuring most base metals had dropped out of solution. "Big Mistake". The blue/green paste and slow filtering gel was what I encountered as a result.

It is my opinion nitric/phosphoric works great at removeing gold plate from PC Cards, just make sure you do some good housekeeping to avoid contamination from say Tin, or Aluminum.


:lol: Nick