Thank you all for your answers!
Geraldo, you have given lots of good keywords to do my own search now and even more than I asked, you have already explained a lot! I had a diffuse feeling of, it could have to do with the things you mentioned, like electrons, crystal structures, space between atoms, but I just didn't know, which words to search for. Thank you so much!
GSP, you are right. It is just that, what I told my lady yesterday, when I told her proudly from my successful making of a shiny silver button within a school lesson of 45min - from recovering from some silver plated spoons a student gave to me, over refining, washing and finally melting with a cheap little bunsen burner within 5 min - and just when the school bell rang, I handed out the button to the student.
That this was possible for me is only because of the knowledge I gained from you guys, PRACTICAL knowledge. Of course working that fast causes losses of 50%, but I know, where the losses are and they will be recovered another time. There will be a huge army of teachers, who are better than me to explain the theory, but I believe there are only a few, who could have done this trick at all or at least within that short time.
Understand my approach of view, I am not a chemist, my expertise is to catch the interest of young students for the many small miracles of nature - with the intention, they will open their eyes and want actively to gain personal knowledge about it. From the school books they learn some tiny facts about alloys. My intention is to know a little more than those books, so I can make it a little more interesting for them, but they would only listen, if they get the subjective feeling, that I am some kind of "expert" who knows, what he is talking about. I do not need to be able to understand it all, I don't have to build bridges of steel like engineers, but enough to make it interesting for the kids. It would not surprise me, if one or the other boy or girl, who followed the school experiments and the stories with glittering eyes, would become a chemical engineer or a metallurgist in the future.
When you understand me as a theory guy, this is not the whole truth. I absorb all the practical knowledge and the skills I find here every day, it is only because of my profession's socialization, that I tend to ask (mostly myself) questions, that on the surface have no or only little relevance or value for the practice of refining. I believe, there is a lot different kinds of "refiners", some have ores to process, others scrap jewelry, some are owners of whole plants, others do it as a hobby. When I use experiments related to refining in school to explain some matters the students have to learn about, I am as much a refiner, as everyone else on the board and because of the board - with challenges, problems and approaches to just this setting of mine.
I am sure, I am not the only teacher on the board, so I think, this approach is not more off-topic, than when some workers from a plant join in and have some mysterious problems with their cells, even when they only know their own limited process and neither do need or do know, what are basics to most of us, to do their work.
And no, I didn't feel your answer to be extreme, I understand your point of view and when you answer in the way you did, there are two possibilities: I didn't explain myself good enough and you got me wrong OR I am just wrong and off-topic. Both are valid and no reasons to feel bad, but to learn from this and make it better next time.
While writing this, another footnote comes to mind: It is one of the most effective ways to prevent burn-out to take a little from one's hobbies into the one's labour and to take a little labour into the hobbies.
Once again, thank you all so much!