Another idea, taking advantage of the vastness of space and relative masses in another way. Rather than containing the gaseous material could you not vaporize a large amount of material and linearly accelerate it at the same time by a fixed amount. Maybe even a high powered laser could accomplish both at once without physical contact, or a laser combined with a magnetic field. The mass of the heavier metals will mean their ultimate velocity will be significantly less than the lighter ones. Over some distance they would condense back to liquid then solid but would have striated and continue to separate in distance as the relative velocities continues to pull them apart in distance. You could even do this by producing a pulsed beam of material moving towards earth from the mined asteroid. Closer to earth you would collect material in order of arrival and separating them into bins by expected relative arrival time by elemental mass. Would this not lead to a pretty refined mixture and require no physical contact?
To your point about the sublimation points being different slowly heating the material while applying force to the vapor would also increase the separation in space, and leaving some highly concentrated high vapor point platinum group residual alloy to be refined on earth - maybe this would be considerably less wasteful as you would capture everything at the collection point relatively separated with no exotic materials or centrifuges?
Another idea, taking advantage of the vastness of space and relative masses in another way. Rather than containing the gaseous material could you not vaporize a large amount of material and linearly accelerate it at the same time by a fixed amount. Maybe even a high powered laser could accomplish both at once without physical contact, or a laser combined with a magnetic field. The mass of the heavier metals will mean their ultimate velocity will be significantly less than the lighter ones. Over some distance they would condense back to liquid then solid but would have striated and continue to separate in distance as the relative velocities continues to pull them apart in distance. You could even do this by producing a pulsed beam of material moving towards earth from the mined asteroid. Closer to earth you would collect material in order of arrival and separating them into bins by expected relative arrival time by elemental mass. Would this not lead to a pretty refined mixture and require no physical contact?
To your point about the sublimation points being different slowly heating the material while applying force to the vapor would also increase the separation in space, and leaving some highly concentrated high vapor point platinum group residual alloy to be refined on earth - maybe this would be considerably less wasteful as you would capture everything at the collection point relatively separated with no exotic materials or centrifuges?