To prolong the lifetime and reduce the cost of lining refractories of a metal refining furnace, by a method wherein a spray material, a trowel material or a mortar having a specific thickness is applied to the surface of the lining refractories of a metal refining furnace after being constructed so that cracks and/or oxidation of the lining refractories which may occur at the time of drying, preheating or starting of the melting operation can be restricted.

Upon completion of the construction of the lining refractories of a lower vessel 4, a spray material having a thickness of more than 10mm, more specifically in a range of 10-30mm is applied to the surface of inner refractories of the side wall 1, the vessel bottom 2 and a return flow tube 3. Then, with a gas burner, only the inside ambient temperature of the lower vessel 4 is elevated to 400°C and is dried for approximately 20 hours. Subsequently, magnesia-carbon bricks are constructed along the inner periphery of an immersing tube 5, while alumina-base castable materiel containing approximately 10 percent by weight of magnesia is applied to the lower end and the outer periphery of the immersing tube 5. Then, a trowel material 7 is applied to the inner surface of the immersing tube 5 at a thickness of 15mm. Subsequently, with a gas burner, only the inside ambient temperature of the immersing tube 5 is elevated to 400°C and is dried for approximately 12 hours. Due to such a construction, the occurrence of cracks and/or oxidation on the lining refractories can be prevented.