US Patent 7841379 Method and system for pumping molten metal

Method and apparatus for pumping molten metal from a reservoir into a preferably bottom-filled mold includes a pair of graphite pump crucibles partially submerged in a reservoir of molten metal. Check valves in the bottom of each crucible enable them to be filled to the same level as the reservoir. A high pressure inert gas supply operating through a pressure regulator, forces the molten metal from one of the crucibles up a riser tube to a horizontally extending runner and through a fill port into the mold. The pressure supply is then connected to the other crucible while the first refills.