Melting furnace purge system and method

An apparatus comprising:

• a furnace structure defining a melting chamber, a charge port configured for entry of metal pieces into the melting chamber, and a discharge port configured to drain molten metal from the melting chamber, including a block of refractory material having a surface within the melting chamber at a peripheral boundary of the melting chamber;
• a source of inert gas;
• and
• a port structure communicating with the source of inert gas, wherein the port structure is open at the surface of the block and is configured to direct inert gas downward over the surface of the block.

A method of operating a furnace having a melting chamber with a periphery defined by a surrounding wall structure, a charge port configured for entry of metal pieces into the melting chamber, and a discharge port configured to drain molten metal from the melting chamber;

• the method comprising:
• providing the melting chamber with an atmosphere including air;
• and
• directing inert gas to flow downward in the melting chamber in the configuration of a curtain that adjoins the wall structure and reaches only partially around the periphery of the melting chamber, to form an upper surface by flowing horizontally from a lower end of the curtain, and to increase in depth such that the upper surface rises in the melting chamber to displace the air from the melting chamber.