Fastest way to digest inquarted gold in nitric?

[autumnwillow]

The material is in corn flakes form and have tried the following:

Premixed 2:1 ratio of water to 70% nitric. Adding in small amounts to control fumes. Then decanting the solution, crushing the flakes after that use 1:1 ratio. Results are about 5 hours of digest.

Used 1:1 ratio for H2O and 70% nitric. Adding in small amounts to control fumes. Same result.

I'm using a magnetic mixer.
I use about 200ml in total and add about 10ml of 50% H2O2 to control the fumes.
The lots are usually 1kg with about 200g - 250g gold content.
All digestions are accompanied with heat, when its overheating we turn the heat off.

I'm thinking lack of surface area, maybe I should roll it thin. Uh but that's 1kg or maybe I should build a system similar to an atomizer but not really an atomizer but should help in providing more surface area.

What are you methods? How fast can you digest?
Do you premix? Or add small amounts of nitric like how you digest in AR?
My observation shows that decanting the solution more frequently results in a faster digest, are there solubility problems when digesting in nitric?

 

[Geo]

Instead of cornflaking, pour the metal into smaller shot to increase the surface area. You are already doing everything else you can do.