Alex,
You changed your post on me while I was typing. Answering your revised post I understand your thoughts but many buyers as well as refiners do not want the competition you speak of because they prefer to keep the markets they have. And yes there is a lot of voodoo in particular when converters are involved.
Below is my response to your original post.
No one wants to chase you off! You have been told the name of the largest platinum group refiner in Europe, Heraeus in Germany. Then you asked the most sought after question when it comes to converters, how much of what is in them. You were told that the individual converters can vary greatly. As for an “average European mix” only a large dealer or refiner in Europe would have that information. They are very likely not going to want to give you information that helps you become their competition and the refineries will not disclose their customer’s private data. No drama that I saw.
While what you were asking for is very hard to find, this site is simply astounding with the information it does contain. Refining is a very secretive business and never have I seen this much information on it in one place. The site is interactive as well and you can ask questions and very often they are answered, but not always. Sit back and enjoy the information, this site is free and one of the few exceptions I have seen to the rule “you get what you pay for” as with this site you get far more than you paid.