the overwhelming success of the very deep hole, page-31

"You cannot suck molten gold through a straw more than 65 centimeters long, no matter how hard you suck.
This calculation is made on the principle which a Torricelli barometer works"

Well ...I ain't heard of no Torricelli barometer .. but I have a plan.
If ya heat up the "straw", aka the MGSD, (Molten Gold Suction Device) the Gold would remain molten until reaching the surface. The Gold would then have to be filtered to remove the impurities and then poured into the ingot trays. To help with the suction, and bypass the Torricelli thingy, a parallel "straw" with the filtered impurities, aka the IRP, (Impurities Return Pipe) could be returned undergrond thus creating a syphyoning effect. As the resevoir of molten Gold lowered so would the inlet of the MGSD to advoid sucking the impurities back up that would be floating on the surface.
Anyway, I reckon it'd work.