Abstract: A wood pulp grinder includes a grinder housing for supporting wood to be ground above a grindstone. A main press chamber in the grinder housing supports a main press ram which moves toward and away from the grindstone. When the main press ram is upraised, the main press chamber is charged with wood to be ground. Adjacent one or both circumferential sides of the main press chamber is disposed a respective auxiliary press ram with is movable toward the grindstone independently of the motion of the main press ram for retaining pressure upon the wood in the grinder housing while the main press ram is not pressing upon the wood. The auxiliary press ram or rams are relatively long in a lengthwise direction, having a length equal to fifty percent and preferably at least eighty percent of their active press stroke. The active lower surface of the auxiliary press ram may be inclined generally in a direction tangent to the surface of the grindstone or may be curved convexly toward the grindstone.

Abstract: A flotation cell featuring a mixing pipe which enters the suspension essentially vertically, follows the point of air intake, and generally receives the entire suspension quantity per flotation cell, the injector of the flotation cell is offset sideways relative to the vertical center axis of the round container cross-section and away from the side on which the foam removal opening and the liquid drain opening are located. The mixing pipe (1) enters the suspension only for a distance such that its discharge opening, mouth (2), is located at least at one-half the height of the level of the overflow edge (7) of the foam removal channel (8), figured from the container bottom. The liquid drain opening (9) is preferably provided in the immediate vicinity of the container bottom, with a cover plate (11) extending across the length of the flotation cell and forming a drain channel (12) into which proceeds the clean liquid through an upper (14) and a lower (13) slot.

Abstract: A sorter having a rotationally symmetric screen including a drain space for receiving overflow material (rejects) connected axially above the screen. A screen space is provided radially outside of the screen and an accepts drain space is connected to the screen space above the screen and surrounding the drain space. The screen space receives the flow through material (accepts) and, in its upper portion, includes a gas space for dampening.

Abstract: The disclosure concerns a process for grinding wood on a grinding stone and the grinding stone which grinds the wood. The grinding stone has a central core, which may be comprised of concrete or steel. The core has a free inner space. A water supply line extends along the free inner space. Outlets from the water supply line are directed toward the periphery of the core at the grinding zone of the grinding layer. Around the core is a grinding layer for grinding the wood. The grinding layer is permeable so that water can be transmitted through it. The permeability may arise from the porosity of the material of the grinding layer itself or through the provision of bores or gaps in the grinding layer. The grinding layer may be comprised of a group of segments covering the core and the gaps may be defined between segments. The core may have bores for delivering the water to the inside of the grinding layer. The water may be heated and/or pressurized for improving grinding.