DORR-OLIVER Horizontal Pan Filter (HPF)

Advanced Technology for economic filtration of fast filtering products, in combination with effective cake washing and drying.

Dorr-Oliver HPF
  • Overview
  • Alumina design

Time-tested technology - innovative developments

The DORR-OLIVER Horizontal Pan Filter is a continuous vacuum filter designed for economic filtration of granular, fibrous and coarse fast settling solids, including cake washing and drying if required. The DORR-OLIVER Horizontal Pan Filter provides a circular filtration surface (“pan”) rotating in a horizontal plane. Multiple filter designs, filter sizes and process components are available, suitable for a wide range of industrial applications and process needs.

The unique filter design allows for cake washing in counter current mode thereby achieving highest cake washing efficiency at reduced wash media consumption. The cake moisture is effectively reduced by means of the applied vacuum and additional methods if required before it is removed by a wear resistant cake discharge scroll. The filtration surface can be dressed with a wide range of textile and metal type of filter media thereby using most advanced cloth fixing methods including cassette designs.

DORR-OLIVER Horizontal Pan Filters are typically manufactured in an all-steel design considering the material selection most suitable for the individual application. In combination with the heavy duty filter design a highly reliable and maintenance friendly filter is provided.

The results of 60 years experience and superior performance have been proven in literally almost thousands of installations and various applications. Simplicity of design, operation visibility and great reliability are the remarkable features of this lowest capital cost/ton of product horizontal filter.

Features and Benefits

  • Continuous Horizontal Pan Filter divided into sectors, equipped with individual fixed filter media, rotating around a vertical axis
  • Cake drying by vacuum and steam or hot air
  • Material of construction: mild steel, alloys, rubber-lined mild steel
  • Gas-tight design


Check out these advantages:

  • Highest capacities per square meter due to maximum discharge areas through drainage deck and stream lined filter valve 
  • Lowest cake moisture due to high hydraulic and pneumatic capacities 
  • Vacuum up to 150 mbar abs. 
  • Effective separation of wash media on the filter deck during single or multi-stage co-/ counter current displacement wash 
  • Air back blow in feed area for heel cake re-slurrying and filter media cleaning 
  • Efficient filter cake drying using steam, hot air or other methods

Product hydrate filtration prior calcination, cake washing and drying

The Alumina Horizontal Pan Filter is designed for the latest state-of the art process needs to product hydrate filtration in the Bayer process. The latest designs are a result of more then 220 pan filters in operation in alumina refineries around the globe comprising more then 8,000 m² of filtration area.

Latest filter designs are addressing the needs of modern calciner designs including plant layout and process control.


  • The latest DORR-OLIVER Alumina Pan Filter designs are the answer to the actual needs in the alumina industry. They combine individual process needs with a reliable and rugged equipment design for highest customer satisfaction.
  • A wide range of filter sizes is available up to a filtration area of currently 71m² comprising a pan diameter of approx. 10 m. 
  • Highest throughputs are achieved by applying advanced filter design methods improving hydraulic and pneumatic filter characteristics thereby increasing filtration rate and cake solids concentration. 
  • Uniform hydrate slurry distribution is achieved by the well proven feeding device resulting in an even cake build-up over the full pan width. 
  • Superior product hydrate characteristics are achieved due to heel cake filtration in combination with up to three counter current cake wash stages thereby minimizing condensate consumption. 
  • Effective cake moisture reduction is achieved by applying low pressure plant steam resulting in most economic filter operation. 
  • A variety of advanced filter media and media fixing methods are available including cassette designs for safe and trouble-free cloth replacement. 
  • Continuous and discontinuous cloth cleaning methods are in place for achieving constantly high throughputs and longest filter media life. 
  • Advanced self control features for reliable operation are a standard feature of our filter designs. 
  • Reliable cake discharge is affected by the wear resistant discharge scroll.

HPF in operation