The Tilting Pan Filter

The Tilting Pan Filter is predominantly employed in the phosphoric acid industry and, to some extent, in the washing of phosphate rock. There was a traditional rivalry over the years between the Pan and Belt Filter which now, owing to the substantial progress in rubber technology, swings in the favor of the later. The operation of Tilting Pan Filters is based on a series of horizontal independent 

The main valve, which is called the distributor, controls the cycle segments with bridges that open and close the port of each pan as it passes from high vacuum through cake blow-off to low vacuum. 

Compartments within the valve separate the various zones to ensure that the separation is sharp and no mixing of mother, strong, middle and weak filtrates occurs during the cycle. To speed up the evacuation of the various filtrates there are valves with two bridge circles, one for the main stream and the another that opens to atmosphere and purges the pan below the deck just before entering a new zone. 

The speed of rotation establishes the cycle time and this, being an important design parameter, is limited mechanically by the mass inertia of the swinging pan and its wet cake load at the point 

The cycle of a Tilting Pan Filter that includes three counter-current washing stages consists of the following zones  

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Figure 1.25 Schematic representation of the tilting pan filter cycle.

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