Composite fireproof plate prefabricated part for fire hole of aluminum melting furnace

The upper end face of an aluminum melting furnace is provided with an upper blocking piece surrounding the furnace fire opening, the upper blocking piece is of an annular structure, the inner diameter of the upper blocking piece is not larger than that of the furnace fire opening, the outer wall of the upper blocking piece is provided with a heat insulation layer, the inner wall of the upper blocking piece is provided with a heat-resisting layer, and one side of the upper blocking piece is provided with a feeding opening. A feeding cover matched with the feeding port is hinged to the lower edge of the feeding port, a transverse rod A is arranged on the lower portion of the feeding port, a sliding supporting piece used for supporting the opened feeding cover is arranged on the transverse rod A in a sliding fit mode, a feeding sliding way is formed in the inner face of the feeding cover, and an exhaust port is formed in the upper portion of the upper blocking piece; according to the aluminum melting furnace fir