German materials handling specialist IBAU Hamburg has developed mechanical ship unloaders with screw conveyors that can provide a highly-efficient solution to discharge cement from ships.
The systems has low energy consumption and maintenance and provides a dust-free unloading operation.
The unloader has four separate screw conveyors :
Vertical screw 1 picks up the material assisted by a counter-rotating outer screw. Filling factors of up to 60 per cent can be achieved
Vertical screw 2 raises the material to the conveying height required for onward transport
Screw 3 provides the horizontal transport from the hold to the material transfer point. The efficiency of the screw conveyor is higher with a downward sloping screw. The required lifting height of only 4m above ground level ensures that the horizontal screw is actually in a horizontal position or inclined downwards for over 80 per cent of the unloading time. Therefore, less energy is needed for conveying and equipment is subject to less wear.
A fourth screw (loading screw) either loads the material directly into trucks or transfers it to a downstream mechanical or pneumatic transport unit.