Method for treatment of suspensions in movement

A method of treating a suspension flowing through a container in a first direction, the container elongated in a dimension coextensive with said first direction and having mounted therein a screen body reciprocal in the dimension of elongation of the container both in the first direction and in a second direction opposite the first direction, the screen body having a perforated screen surface defining a screen cavity volume therewithin, said method comprising the steps of:

• (a) introducing suspension under a motive force into the container inlet and withdrawing it from the container outlet so that it flows in the first direction within the container;
• (b) effecting movement of the screen body in the first and second directions within the container to extract some of the liquid from the moving suspension within the container so that it flows into the screen cavity volume;
• (c) withdrawing the liquid passing into the screen cavity volume from that volume to an area remote from the container;
• and
• (d) introducing treatment liquid into the container, from an interior sidewall of the container, so that during liquid extraction with the screen body a crosswise flow of treatment liquid is obtained through substantially all suspension flowing through the container;
• and wherein at the points of treatment liquid introduction a baffle plate is provided directing the treatment liquid in the first direction, and substantially evenly around the entire circumference of the container, and wherein step (d) is practiced by introduced treatment liquid into the container adjacent each baffle plate so that the treatment liquid initially has a velocity component in the first direction and is introduced substantially evenly around the circumference of the container.