Is it safe to mix all of those chemicals together????
I believe you should try known combinations.
It gets tuff but a lot of information is found when you start searching for answers you need.
Searching and reading on the GRF is recommended.
I remember when I did a HCl Bleach combo several years ago and it would not get all the solids into solution.
Those solid remainders in the beaker were a different color too.
You can use just a nitric boil. Nitric itself will not dissolve the gold.
You can use just a HCl boil. HCl will not dissolve the gold.
HCl and peroxide will take gold into solution and possibly there may be solid remainders left.
However when trying to remove metal solids and clean up your gold each choice or combination you choose its best to thouroughly rinse your solids to a neutral PH.
Ph paper comes in handy. There were times I rinsed all clear but it was not neutral Ph so the acid was still in there.
I learned rinsing takes a few more times after a clear rinse.
You don't need much acids and rinses to clean up small amounts. Be sort of minimal generating least amount of waste to get the job done.
Have some dedicated waste stock pots these wash acids can be saved and have reuse.
If you get real good at saving waste eventually you can learn how to specifically electrolyze metals and condense acids back out.
Personally I find this interesting.