NEW PERFORMANCES IN SEED FILTRATION BY MODERN DISC FILTERS: A FEASIBILITY REVIEW

Hahn, J., Langeloh, Th., Bott, R. and Banerjee, S.K.

The filtration of coarse and fine seed downstream the secondary or tertiary thickener or in continuation of hydrocyclones, respectively, influence remarkably the effectiveness, the operational cost and the quality of the final product in Alumina precipitation plants. The filtered solids are normally reslurried in stirred tanks or given directly to the precipitation tank, if the filter is installed on top of the precipitators.

For seed filtration mainly rotary vacuum disc filters are used. In the last five years a new generation of big diameter disc filters (type ‘Boozer’) has been developed and installed world-wide, characterised by:

  • very high specific throughput rates
  • reliable, 100% cake discharge
  • high operational availability and low maintenance cost
  • easy and safe handling of the filter components
  • low operational cost for vacuum, pressurised air and filter cloth consumption
  • safe operation due to a superior process philosophy applied in a PLC/LCP system

The “Boozer” filter generation is in operation for more than five years for different duties and has been developed permanently since.

Based on the latest installation in an Indian Alumina refinery the report will show the integration of the Boozer filters in the precipitation and calcination plant and summarise the practical experiences from the standpoint of the user and the operators, respectively. The reasons and the arguments which led to the order for the Boozer filters will be discussed.