The suspension to be filtered is fed continuously to the filter trough. Depending on the application, different systems are available to guarantee homogeneous mixing of the slurry. Thanks to the specially designed pendulum agitator from ANDRITZ SEPARATION, sedimentation of the solids is prevented.
The shell of the filter drum is divided into cells and covered by a filter cloth. Approximately 37% of the filtration area is submerged in the suspension, and the drum rotates at up to 4 rpm.
The Krauss-Maffei vacuum drum filter TSF builds up a vacuum with a liquid seal pump, which is connected to the drum cells via separators, control head, and filtrate pipes. This causes the liquid to filter through the filter cloth. The solids contained in the suspension are deposited in a uniform layer on the filter cloth, thus forming a filter cake.
The filtrate is discharged either by pumping or by utilizing the barometric height. The filtered solids layer emerges from the slurry as the drum rotates and is then washed, dried, and removed from the filter cloth. In the course of one revolution, each point of the drum area passes through these zones in succession.
The wash liquid is applied to the cake either directly by washing devices (weirs, spray nozzles) or through a wash belt placed on top of the solids layer.
The filtrates from the washing zones can be drained off separately, enabling multi-stage counter-current washing. The filter cake is discharged by means of a discharge device covering the entire drum width and which is specially suited to the cake thickness, consistency, structure, and so on (scraper, roller, pre-coat scraper, string or belt discharge).
Krauss-Maffei TSF discharge systems