Today I took 277.9gms of silver inquarted gold & tried the 50% H2O2/ 50% nitric. I used the 38ml nitric /1 oz. recommended on the forum, so I need 340ml or little over 11 oz.
I added the first 4 oz & after 10 min the reaction was slow & no fumes. I added another 4 oz, & reaction started to increase. No fumes. After 5 minutes, oh boy... dark brown fumes & a 1in. foam head. I slowly added about a cup of H2O2, but still the red fumes & more reaction. Within 45 min. it was 98% done. No heat was used. Red fumes were gone, so I added 2 oz of H2O2 in case it was needed to continue the reaction, but it was over in less then 1 hr. No reaction other than a feeze. On previous batches a used water/nitric & heat, & it took 3 good hrs. Couple good things, I didn't get hurt & I saved 3.5 oz of nitric. :lol:
So I would say that a 75 H2O2/25 nitric mix, for starting the batch would be safer & easier to control. Add any nitric or H2O2 as needed to finish disolving base metals. Needless to say, add nitric slowly.
Please, some input from our experts.
Thanks!
philddreamer