METHOD FOR CONTROLLING A FLOTATION PROCESS FOR DE-INKING USED PAPER

摘要

The invention relates to a method for removing solids from an aqueous fibrous suspension (1) by means of gas bubbles in a flotation unit comprising a plurality of flotation cells (2), wherein a fibrous suspension gas mixture (3) is supplied to form a flotation foam (4) which collects solids and is routed from the flotation cells (2) via an overflow (5) into at least one foam collecting channel (6) where it is accumulated, wherein the fibrous suspension released from the solids is discharged as accepted stock (7) from the respective flotation cell (2) and the quantity of flotation foam (4) flowing out of the foam collecting channel (6) can be altered via a control (8) on the basis of at least one parameter of the accepted stock (7). The aim is to achieve an efficient flotation with the highest possible yield and high-quality accepted stock (7) in that at least in one flotation cell (2), the quantity of the supplied fibrous suspension gas mixture (3) is altered by the control (8) in such a way that the height of the suspension level remains constant in this flotation cell (2). In order to improve speed and accuracy, when at least in one flotation cell (2), immediately after a change to the quantity of the flotation foam (4) discharged from the foam collecting channel (6), the quantity of the supplied fibrous suspension gas mixture is altered by the control (8).