You will have to use PINE WOOD as a flux anyway!!!!!!! Why separate anything????????
Just leave it in there and let it burn and carbonize. You will probably have to add more WOOD to the re-melt to clean all the gunk out. Just let it melt. You are gonna make wood smoke if you re-melt it right anyway!!!!! 3X fluing with the final one wood + wax (beeswax is my standard).
You have nothing to fear.......if you every plan on re-melting anything into ingots....you HAVE to flux it with wood and wax.
Banger