An apparatus for cleaning a fiber mass suspension, the apparatus comprising a receptacle and an inlet channel and an outlet channel for feeding the suspension into and for discharging it from the receptacle. In addition, the apparatus comprises air feed means for feeding air into the lower portion of the receptacle. The apparatus comprises at least one partition wall dividing the receptacle into spaces in such a way that the suspension may flow between the spaces at the lower portion and the upper portion of the partition wall, respectively. The air feeding means are positioned to feed air into one aeration space, whereby the air separates impurities from the suspension and makes the suspension flow on different sides of the partition wall upwards and downwards, respectively, so that a spiral flow is created around the partition wall from the inlet channel into the outlet channel.
展开▼
