Molten cast iron at 1100 C ?

I stumbled upon this video of Nobox7. He does excellent experiments and makes exotic burners.
One of them he tried to melt 479g of cast iron in only 8 minutes from a cold furnace with a propane burner with his exotic burner design.
At 8:15 the iron is molten and at 9:45 he starts to measure temperature which shows 2000 F (1100 C) and the metal is still partly molten.
Anyway to get the metal in the crucible to 1370 C in only 8 minutes is a marvel and at that temp it is (mostly) liquid. But still partly liquid when cooled to 1100 C, is this cast iron ? At 1100 C is already well below freezing temperature.