An improved molten metal furnace including an enlarged buffer plate of nickel-based superalloy material which seals and separates the furnace burners from the product to be heated. The metal film encapsulation may provide contact tabs for the electrochemical device. At this time, if a predetermined upper limit value that is standard for return is relatively high, a return is less likely to occur. Two ends of the static elimination device are free to rotate and connected to shelf holders at said end side. The isolate electrode has a first height, and the electron emission region has a second height smaller than the first height.