I can't answer your question if you can granulate gold granules onto a silver surface with certainty, but I quite doubt it.
Yes, you can definitely granulate gold onto silver. Harold O’Connor
does it all the time in his wonderful jewelry and uses a torch to do
it. Unfortunately, I’m not an expert in granulation so I can’t talk
you through the procedure, but perhaps someone else can. Otherwise, I
suggest you keep an eye on the ads for various schools and classes in
Metalsmith magazine. Harold periodically teaches workshop in
granulation, reticulation, and other techniques. He has also written
several books and, while I don’t know the titles, there may be one
about granulation.
Beth