garodin,
There are thousands of posts on this subject, every thing you need to learn to make nitric acid to use to recover and refine precious metals has been provided on the forum, with some study you can learn it easily, if you wish to learn I suggest beginning with the safety section, then the guide to the forum, and then searching and reading more about it on the forum, from that you will learn how to make poor mans nitric and even how to distill it to get a product of nitric acid of high purity that will even work when you are working with silver and want a nitric without other sulfate salts, or chlorides that may interfere in that process.
As with most of this study on the forum, study to learn the basics, and when you need more help or get stuck with your study, ask questions, and members will be glad to help with the details, you may have trouble with.
I have not had to ask any questions about nitric acid and how to make it. I learned from reading the forum, and have done my own research to further my knowledge in the subject.
It did take some time, but I now have a vast knowledge of the subject (at least as much as I feel I need to satisfy my own interest in the subject at this time). I have also posted a lot about it, I have also acquired a large note book dedicated just to the subject of nitric acid and its chemistry, from notes on the subject I made while studying, so if you study it and need some help with your study I will be glad to help you along with your study where I can.