An operating method of a melting furnace comprising - a vessel provided with a bottom; - a tapping duct passing through the bottom and having a first stretch arranged in the thickness of the bottom and completely passing through the bottom, and a second stretch, adjacent to the first stretch, protruding inside the vessel; - a fixed cover of the second stretch shaped as a bell, closed at an upper end thereof and open at a lower end thereof; said bell being coaxial and spaced from said second stretch, and being spaced from a zone of the bottom which includes the first stretch of the tapping duct, whereby the fixed cover, in cooperation with the second stretch of the tapping duct, defines a volume inside the fixed cover and adapted to act as a tapping hood; - rotation means adapted to rotate the vessel so that the tapping duct passes from a first reference position to a second position inclined with respect to said first reference position, and vice versa; the method comprising the following steps: a) providing the vessel with the tapping duct in the first reference position and providing a bath of molten metal material at an equal level both inside and outside the cover and comprised between the lower end of the cover and an upper edge of the second stretch, a slag being kept on the surface of said bath outside the cover; b) rotating the vessel in a first direction so that the tapping duct passes from said first reference position to said second position inclined until the level of molten metal material reaches the upper edge of the second stretch so that the molten metal material begins to be tapped through the tapping duct creating a depression inside the volume; c) rotating the vessel in a second direction, opposite the first direction, so that the tapping duct returns to the first reference position, while, due to said depression, the molten metal material passes from the outside of the cover to the inside of the volume and continues to be tapped through the tapping duct until said depression is canceled. - a vessel provided with a bottom; - a tapping duct passing through the bottom and having a first stretch arranged in the thickness of the bottom and completely passing through the bottom, and a second stretch, adjacent to the first stretch, protruding inside the vessel; - a fixed cover of the second stretch shaped as a bell, closed at an upper end thereof and open at a lower end thereof; said bell being coaxial and spaced from said second stretch, and being spaced from a zone of the bottom which includes the first stretch of the tapping duct, whereby the fixed cover, in cooperation with the second stretch of the tapping duct, defines a volume inside the fixed cover and adapted to act as a tapping hood; - rotation means adapted to rotate the vessel so that the tapping duct passes from a first reference position to a second position inclined with respect to said first reference position, and vice versa; a) providing the vessel with the tapping duct in the first reference position and providing a bath of molten metal material at an equal level both inside and outside the cover and comprised between the lower end of the cover and an upper edge of the second stretch, a slag being kept on the surface of said bath outside the cover; b) rotating the vessel in a first direction so that the tapping duct passes from said first reference position to said second position inclined until the level of molten metal material reaches the upper edge of the second stretch so that the molten metal material begins to be tapped through the tapping duct creating a depression inside the volume; c) rotating the vessel in a second direction, opposite the first direction, so that the tapping duct returns to the first reference position, while, due to said depression, the molten metal material passes from the outside of the cover to the inside of the volume and continues to be tapped through the tapping duct until said depression is canceled.