How to separate Na metal from Mg / MgO leftovers

The reaction of NaOH (drain cleaner) with Mg metal powder is very vigorous, so I do it in a metal container.

But afterwards, the leftover contains Na metal, but mixed with Mg and MgO.
I heated it to 200 C (well above Na melting point of 97 C) under oil, but could not separate it.
How can I separate this ?



[Edited on 2019-8-11 by metalresearcher]