Rotary Drum Filters (RDF)

Standard or Custom-Engineered Designs for Dewatering, Washing & Clarification

Conventional Rotary Drum Filter
  • General
  • Operation Benefits and Advantages
  • Red Mud Filter for alumina

About the Filters

Drum Filter Capabilities
The unique capabilities of drum filters provide the widest application range of any continuous vacuum filter: Drum filters have the operating flexibility to handle either dewatering, washing, or clarification applications.

With increased emphasis on reducing capital, operation and maintenance costs and improving productivity, it is important to understand the opportunities for enhanced dewatering, washing, and clarification presented by different filter designs.
Proven technology
With the reliable and well-known Dorr-Oliver and Eimco technology, FLSmidth has gained extensive know-how which is the basis of our success. Our know-how linked with the continuous improvements of our processes and machines is leading to best performance, high energy efficiency and maximum economical solutions.


Design Variables

Each FLSmidth drum filter is designed exactly to customer's specific requirements. Usually one of our three types of discharge can be supplied, depending on the cake properties:

  • Drum Filter with Scraper Discharge

The Scraper discharge is a simple method that covers most filtration applications. The cake has to be at least 3 mm thick.

  • Drum Filter with Roller Discharge

For thin filter cakes, a Roller with axis parallel to the drum, but running in contact with the cake at a different rotational speed, serves as the cake discharge medium.

  • Drum Filter with belt discharge

The Belt or "Webtrol" is a discharge device which works well for applications involving fine suspended particles.

Main Features

  • High Capacity

Continuous high production for maximum filtering capacity - wide latitude in productivity per unit area.

  • Low Operation Cost

Minimium maintenance due to easy operation and simple control features.

  • Efficient Vacuum Use

Optimal hydraulic design and a minimum atmospheric air leakages deliver dryer cake at lower vacuum cost.

  • Excellent Filtrate Clarity

Drum Filters frequently produce solids as low as 100 PPM. Precoat designs can achieve concentrations of 10 PPM or less.

  • Effective Cake Washing

High purity of valuable product can be achieved with cake washing.

  • Flexibility

Frequency controlled drives allow high flexibility to varying feed conditions.

Overview and Advantages

  • High flow filter cells for highest hydraulic and pneumatic capacities 
  • Air sweeping device at both ends of the drum cell to assure quick filtrate and cake discharge 
  • Optimised vacuum valves and wear plate with large sealing area for long resistance to wear 
  • Dedicated discharge roller drive system – allowing for optimising ration of drum vs. discharge roller speed 
  • The agitator drive design for easy maintenance access to the drive, the bearings and the excenters; especially the agitator shaft is divided in such a way, that also inside eccenter-bearings can be dismantled and replaced without disassembling the eccenter and the outside bearing 
    The agitator drive is supported on the filter vat (not on the foundation) for best fit of the components in the workshop and after site erection
  • Robust cake discharge comb in special red mud design
  • The agitator pivot bearings can be replaced from the outside without disassembling the drum. They are provided with lubrication points to assure to the bearings a long life
  • Mud pockets with sluicing pipes and drainage nozzles to temporarily drain out the settled sand

Red Mud Filter for alumina