Abstract: The invention relates to a metallurgical reactor for the treatment under reduced pressure of a liquid metal (1) such as steel, contained in a ladle (2), of the type comprising a chamber (25), connected to a gas-suction plant (30) which can maintain a reduced pressure therein, and two tubular snorkels (26, 27), the upper ends of which emerge in orifices (35, 36) made in the bottom (28) of the chamber (25) and the lower ends of which may be immersed in said liquid metal (1) contained in said ladle (2), one (26) of said snorkels, called the "ascending snorkel", having means (29) for injecting a gas into its internal space for the purpose of creating a circulatory motion in the liquid metal (1) between the ladle (2) and the chamber (25) during said treatment, the reactor also comprising an enclosure (17) which is provided with means (20) for injecting a gas into its internal space, these means being suitable for creating a pressure greater than atmospheric pressure in the enclosure (17), and the ladle (2) being p