Metals are smelted properly. An electrolytic smelting furnace includes a furnace body, a furnace bottom electrode provided at a bottom part in the furnace body, and an upper electrode provided above the furnace bottom electrode in the furnace body, and the upper electrode includes a conductive compound with a spinel-type structure.

In a molten metal pump, which includes a pump chamber portion and a drive unit and drives molten metal in a pump chamber of the pump chamber portion by the drive unit for discharging and sucking, the pump chamber portion has an outer cylinder and an inner cylinder detachably housed in the outer cylinder, the outer cylinder is configured as a bottomed cylindrical body having an outer cylinder bottom wall and an outer cylinder side wall, the inner cylinder is configured as a bottomed cylindrical body having an inner cylinder bottom wall and an inner cylinder side wall, a ring-shaped spacer, which is interposed between an inner surface of the outer cylinder bottom wall and an outer surface of the inner cylinder bottom wall in a sealed state and in a detachable manner, is further provided.

In a molten metal pump, which includes a pump chamber portion and a drive unit and drives molten metal in a pump chamber of the pump chamber portion by the drive unit for discharging and sucking, the pump chamber portion has an outer cylinder and an inner cylinder detachably housed in the outer cylinder, the outer cylinder is configured as a bottomed cylindrical body having an outer cylinder bottom wall and an outer cylinder side wall, the inner cylinder is configured as a bottomed cylindrical body having an inner cylinder bottom wall and an inner cylinder side wall, a ring-shaped spacer, which is interposed between an inner surface of the outer cylinder bottom wall and an outer surface of the inner cylinder bottom wall in a sealed state and in a detachable manner, is further provided.