Dr.Bob - 29-10-2014 at 16:45
That is somewhat similar to how mass spectroscopy works as well as some forms of isotopic enrichment. The problem is that it is not very practical
for purifying metals except for very expensive ones. Creating a vacuum on earth is not too hard, so that part is easy, overcoming gravity is not
that difficult in most cases, so it can work about as well on earth. But it might be easier to create an artificial gravity in space to separate
minerals by density, which is a common way to do it (panning for gold, floating certain metals on dense solvents, blowing light plastics out of
recycle mixtures). The real problem is that this type of technique is slow since you are separating one atom or particle at a time. Methods that
can sort huge amounts, life sifting, panning, floating, etc are much more practical unless you have an infinite amount of time. The more parallel the
method the better and the more scalable, typically.