Recovering invisible gold

[kernels]

Hi guys,

So far whenever I have dissolved any gold in AR, the gold has been visible and I could visually observe when all the gold had dissolved and stop adding small increments of Nitric. How do you guys know when to stop adding Nitric when recovering gold from things like IC dies where the gold is not obvious ?

 

[Geo]

Watch for the reaction bubbles. They can be tiny, so you may have to shine a light through the solution to see them. No bubbles means it has deplete one or more reagents. Reagents being HCl, nitric acid and metal.

 

[kernels]

Watch for the reaction bubbles. They can be tiny, so you may have to shine a light through the solution to see them. No bubbles means it has deplete one or more reagents. Reagents being HCl, nitric acid and metal.

GREAT tip, thanks for that GEO, so simple . . . why didn't I think of that.

 

[g_axelsson]

The braze holding the die in the ceramic base is dissolved when the die drops off or can easily be dislodged by a gentle push. Preferable with a glass rod while leaching or after the gold chloride has been washed off the ceramics.
Any ceramics with the die still attached after leaching goes back into the next lot.

Göran

 

[Justincase]

When you think you have finished a large lot.
Mix well and take a small represented sample to run again.
A lot has not been fully digested until you have tested and found nothing.

 

[goldsilverpro]

Never boil the solution while dissolving. It masks any reaction that might be occuring.

 

[Refining Rick]

I can't recall exactly who on this forum recommended it, but I have found a cheap laser pointer to work astoundingly well for checking for very small particles and reaction bubbles in solution. Just do not point it in your eyes. (Don't know why I had to say that...)

 

[patnor1011]

And if you do not have laser pointer you can make one from parts from old DVD RW ROM.