Could you use a centrifuge to separate the elements instead of vaporizing it?

You cannot use a centrifuge to separate solid iron.

Using a centrifuge with liquid iron would create a gradient of concentration of the heavier elements dissolved in it, but that would not be enough to separate them.

All that could be done with a centrifuge with liquid iron would be to obtain an iron alloy enriched in heavy elements. However, I doubt that it would be possible to make a centrifuge for liquid iron that would have a lifetime sufficient to process quantities of the order of one million tons of iron. I do not think that until now anyone has ever tried to make a centrifuge that could work with a liquid metal at such a temperature. Most materials lose their strength at such temperatures, so the risk of breakage for the centrifuge would be extremely high, a risk that is increased by how heavy iron is.

It is also not clear if such an enrichment of the heavy elements would bring a sufficient simplification to further processing steps to make it worthwhile.