Abstract: A rotary drum plant is disclosed in which a unique system for directing a liquid medium to the rotating drum is utilized. A rotary drum such as a tube mill has a driving shaft connected thereto, with at least one U-shaped inner ring member having a channel-like cross-section positioned about the shaft and mounted for rotation therewith with the opening of the U-shape facing radially outwardly. At least one stationary ring member has a generally rectangular cross-sectional configuration and is positioned about the rotating U-shaped member to form a generally annular chamber with the U-shaped inner ring. A conduit adapted for carrying a liquid medium such as water communicates the chamber to the rotating drum and rotates therewith, while another liquid conduit directs the liquid medium to the chamber via the stationary ring member.