Abstract: Procedure for preparing hot groundwood from wood chips, wherein a chip stream is conducted into a pressurized steaming chamber, where the chips stay a few minutes and are heated to a temperature higher than 100.degree. C., and from the steaming chamber through a sluice feeder into a hot grinder of enclosed construction, i.e. the stage I grinder, when the pre-ground groundwood is conducted through a separating cyclone into a stage II grinder, the groundwood derived herefrom being conducted towards further treatment steps. The pre-ground groundwood is conducted from the steam separating cyclone through a sluice feeder into the stage II grinder. The stage II grinding is carried out in a hot grinder of enclosed construction.

Abstract: Continuously operating procedure for preparing hot groundwood from wood chips, wherein the chip flow is conducted into a pressurized steaming chamber, where the chips reside a few minutes and are heated to a temperature in excess of 100.degree. C, and from the steaming chamber to a sealing feeder, the rotor of which is circumferentially divided into mutually adjacent compartments, each of which in its turn fills through a feeding aperture with chips and empties in another angular position of the rotor through a discharge opening into a feeding conveyor, which carries the chips to a hot grinder, the groundwood derived from the latter being carried to further treatments, whereat the steam generated by the hot grinder and discharging from its throat in the direction against the chip flow is conducted away from the grinder. The steam is conducted through the feeding conveyor to the sealing feeder, where each compartment, as it is emptied of chips in its turn, fills with steam.