Pusher centrifuges, also called horizontal basket centrifuges, possess filtration bowls equipped with metal screening sheets or slotted sieves. These systems also filter liquids in the centrifugal field and retain solids as filter cakes in the bowls. An oscillating pushing motion transports the cakes out of the bowls. Solids may also be washed with these systems. Pusher centrifuges work continuously and are recommended for large quantities of solids where medium demands are made on the solids’ purity and residual moisture.
A. Suspension inlet
The centrifuge is continuously fed with the suspension to be separated (solid-liquid mixture) via the inlet pipe. In case of poorly flowing products, the feed is effected via an inlet screw conveyor (not shown).
B. Suspension distributor
The distributor accelerates and distributes the suspension over the entire periphery of the sieves in the filling area of the first basket stage. Ferrum offers various application-specific distribution systems for even and gentle acceleration and distribution of the suspension.
C. First basket stage
The greatest part (approx. 80%) of the liquid is already filtered out in the feed zone of the first basket stage, a stable cake forms. The first basket stage performs, along with a rotary movement, also an axial pusher movement (oscillation movement).
D. Second basket stage
The cake is pushed in annular sections by each pusher movement from the first to the second basket.
E. Solids discharge
After the second basket stage, the solids leave the centrifuge via the discharge track and the solids housing. Depending on the application, different discharge systems are used.
F. Product washing
If necessary, impurities in the mother liquor are washed out. The wash liquid is applied continuously over the cake via several adjustable wash nozzles.
G. Filtrate housing
The filtrate (filtered mother liquor and wash liquid) is collected in the filtrate housing and drawn off. Depending on the application, different filtrate housings and filtrate cyclones are used.
H. Filtrate separation
If necessary, the filtrate can be drawn off separately in each filtrate zone by means of separating plates fitted in the filtrate housing and disposed of or reused (e.g. counterflow washing).
The centrifuge process area is cleaned using flush liquid supplied through optimally arranged cleaning nozzles (I) and a clean pipe (J). Periodic flushing prevents the formation of crystals in the sieves and deposits in the solids housing.