vuksi,
Here is my suggestion, store that acid that is so hard to get, it can be used for high grade material, and a little of it (if used properly will process a whole lot of gold), but also using this acid before learning it will be gone in no time with little to no gold to show for it.
There are several work around methods for most all scrap, and learning these you may find you will need hardly any aqua regia, and can use another chemical or process to do the work just as easy and sometimes better.
My suggestion read Hokes book, and study the forum for a while before trying anything, experimenting before you learn can be very wasteful not only of chemicals and precious metals but also your time and money. it is hard to keep from jumping in before you learn but spending a little time studying will save you more than you think.
It is best not to use an exact mix ratio for aqua regia that normally leads to use of excess acids and much more work, and possible problems.
4 fluid ounces of hydrochloric acid will dissolve an ounce of gold with small additions of nitric acid and heated properly (less than a fl Oz HNO3).
Base metal will consume much more of these acids, but you should not use aqua regia on base metals any way, the gold or PGM's should be fairly pure before using aqua regia.
Do you even need to use aqua regia at this point? What are you materials are you working on?
you have a lot more to learn than you think at this point, you have not even got to the top of the mountain to see how far you will need to go or learn yet, take some time studying at least get to the top of the mountain before you begin to try things, it will be easier, and you will make more progress without wasting your valuables, and it will also be much safer for you as some of this chemistry can be very deadly or explosive if done wrong, and until you learn to deal with waste you can poison yourself and many others with the toxic waste if not treated properly, just think of poisoning your neighbors well or a whole towns water supply from doing something you did not understand, when a little study and you can learn to treat the waste safely.
