Abstract: A silencer for use with a tuyere puncher is disclosed. The silencer comprises a chamber having a front face and a rear face provided with a central opening for passing of the punch bar operated by the puncher, a plurality of closure members located in the rear portion of the chamber and mounted for movement toward and away from the longitudinal axis of the chamber and including means for forcing the closure members against the periphery of the punch bar so as to form a seal between the closure members and the punch bar, and a seal secured to the front face of the chamber for engaging the tuyere to seal such a tuyere before penetration of the punch bar through the tuyere valve. The silencer is mounted on a mobile table which is supported by the puncher and operated in synchronism with the punch bar.