Precipitating and refining from concentrated AP

[The Refiner49er]

I bet some of the experts knew this post was inevitable (saw me coming).

I have finished processing several batches of gold trace boards using Acid/Peroxide and 27.5% H2O2. The precipitate (black powder) and solids (mostly yellow Au) have been rinsed well with HCL and water. It looks great in the filter and the boards are virtually 100% stripped.

Is this material ready to be dissolved/precipitated in AR (or other, please advise), or are there additional steps to clarify? There is quite a bit of this material, I wish to sucessfully complete the refining process... devoid of minor catastrophic events.

Thank you for your input.

 

[The Refiner49er]

oops, I think I posted this in the wrong place, am moving it to chemical processes, sorry.

 

[lazersteve]

You should dissolve the clean foils in HCl-Cl (muriatic and clorox ) with stirring. This should take about 5 minutes or less.

Steve

 

[The Refiner49er]

I suspect there is Au dissolved in the AP, I am going to test tomorrow.

If SMB is used to drop the gold, will this invalidate the AP solution?

I favor this process particularly because the solution is restorable/reusable.

Thanks!

 

[Irons]

I suspect there is Au dissolved in the AP, I am going to test tomorrow.

If SMB is used to drop the gold, will this invalidate the AP solution?

I favor this process particularly because the solution is restorable/reusable.

Thanks!

Unless you're triyng to precisely measure your gold recovery from a particular batch, I would leave any Gold that's in the AP there because as soon as you add some more scrap, any Gold will precipitate out from reduction by base metals in the scrap. When the solution gets loaded with base metals and no longer functions well, then recover what values there are and start with fresh AP. The trick is to use as little AP as required to do the job.

 

[eagle2]

The HCl-H2O2 will also dissolve the Copper and Nickel under the Gold.
So the solution gradually becomes a Copper leach. The Copper II (Cupric ion) in solution will continue to dissolve the Copper on the boards. This essentially precips any Gold the HCl-Peroxide dissolved.

You will see a blackish powder mixed in with the Gold bits from the PCB,This is also your gold. Don`t try to separate the two types! When your leach is done let it set overnight in a cool or cold place to let all the black precip collect and fall to the bottom.

Then when you dissolve the contents of the filter in HCl-CL2, you will easily have a clean solution. Any junk that came off the PCB`s and was in your filter along with the gold, can now be separated from the pregnant solution.

Al