Vacuum Filtration with a Disc Filter

The BoVac Disc filter – rotary disc filter for the filtration of large amounts of suspension.

BoVac Disc filters are modern high-performance vacuum disc filters which set new standards with their reliability and cost-effectiveness. They are characterized by extraordinary performance, an extremely large filter area and low space requirement. With regard to filtering and dewatering large quantities of suspension, these filters are unbeatable.

BoVac Disc filters are synonymous with high-performance filtration, reliability and economy in many industries and applications. Engineers around the world appreciate ease-of-use and ease-of-maintenance. When they talk about their experiences with our filters, it is quick and concise: "Switch on and forget".

Due to the typical BOKELA design BoVac Disc filters have outstanding hydraulic properties. Thus. the pressure losses of these vacuum filters are minimal and the pressure difference, which is effective on the filter cloth, is up to 100 % higher than with conventional disc filters.

All components such as filter segments, shaft, filtrate pipes, control head, drive unit and filter trough have been systematically developed. The consequences are extremely high specific throughputs, intensive cake dewatering, high operational reliability as well as low maintenance and low operating costs. The fully automatic operation and the large performance reserves allow a particularly good adaptation to process variations. BoVac Disc filters are therefore characterized by a high degree of flexibility.

BoVac Disc filters are available in various sizes and filter areas up to 352 m2 per filter unit. Due to the modular design with different diameters and variable number of filter discs, BoVac Disc filters can be adapted to specific process conditions.

Applications of the BoVac Disc filter:

BoVac Disc filters are characterized by:

  • up to 100 % more throughput than conventional disc filters
  • very small footprint due to large specific filter surface
  • fully automatic operation
  • high flexibility due to extremely good adaptability to process fluctuations
  • safe operation and high availability
  • easy and fast filter cloth change
  • low maintenance costs
  • fiber-reinforced polymer segments of less than 10 kg in weight (optional)
  • ... runs and runs and runs ...

Each filter disc consists – depending on the diameter – of 20 to 30 filter segments which are mounted on the filter shaft. They are robust and have optimal hydraulic properties. Their special design and very low weight make them easy to assemble and ensure that maintenance is quick and easy – with no safety or health risk for the maintenance team.

A special feature are the fiber-reinforced polymer segments. With a weight of less than 10 kg, they facilitate the re-clothing and maintenance work significantly.

These are the benefits:

  • very light segment weight of only 10 kg for polymer segments and 19.5 kg for metal segments
  • fast and easy segment change due to the special bayonet shape of the segment foot
  • optimized hydraulics ensure fast filtrate drainage and efficient compressed air blow-back for cake discharge
  • shape of segments helps to seal the filter bag and prevents product loss

Each segment mounted on the filter shaft ends with the segment foot in a filtrate collecting pipe. In contrast to conventional filters, the filtrate pipes have no round but a trapezoidal cross-section. This enables a large-sized cross-section of the filtrate pipes with optimum hydraulics through optimal utilization of the available cross-section of the filter shaft.

These are the benefits:

  • optimal hydraulics due to large, trapezoidal filtrate pipes
  • bolted, exchangeable stub shafts allow easy replacement and access to the filtrate tubes
  • shaft seal allows maximum slurry level and maximum capacity
  • slip on gear

The BoVac Disc control head is designed to pre-separate the incoming filtrate/air mixture into a gas and liquid flow. This minimizes pressure loss because in a two-phase flow, the pressure loss is up to ten times higher than in a single-phase flow. Entrainment of filtrate from the cake forming zone in the dewatering zone is prevented even at high filter speed. This ensures a sharp filtrate separation.

These are the benefits:

  • minimum pressure loss through pre-separation design
  • improved flow rates trough flow-optimized design
  • simply changeable wear inserts in place
  • system for cloth protection during compressed air blow-back, meaning longer filter cloth life
  • simplified labyrinth seal to prevent vacuum loss

The design of the BoVac Disc filter trough combines the advantages of different types of filter troughs commonly found in rotary disc filters. Special compartments inside the trough ensure that homogenization of the suspension is caused by the stirring effect of the rotating filter discs. Thus, an agitator is not needed. 

These are the benefits:

  • suspension homogenization without agitator, meaning no leakage, no maintenance, no additional power consumption, high availability
  • same level and uniform cake thickness on all filter discs
  • operation with level control, meaning without suspension overflow
  • 50 % immersion depth of the filter discs, meaning maximum cake formation angle
  • large-dimensioned drain valves that allow a quick trough emptying
  • spray bars for online cloth wash during filter operation
  • permanently installed walkways between the discs for a quick re-clothing

The arrangement of filter and filtrate receiver affects the filter operation, the filter performance and the required space. Therefore, BoVac Disc filters and filtrate receivers are arranged as close and as straight as possible:

  • compact arrangement with minimal space requirement
  • minimal pressure loss due to very short and straight flow path for the filtrate/air mixture between the control head and the separator
  • fail-safe design with barometric foot – no moving parts

BoVac Disc filters are easy to maintain:

  • permanently installed walkways between the filter discs
  • no agitator
  • easy handling of the light filter segments
  • easy and fast segment mounting with bayonet foot
  • easy cloth change
  • online cloth washing
  • maintenance-free shaft seal
Filter Type [–]
M22 M44 M66 M88 M176 L88 L132 L176 XL352
Disc Diameter [m] 4.1 4.1 4.1 4.1 4.1 5.6 5.6 5.6 6.4
No. of Discs [–] 1 2 3 4 8 2 3 4 6
Filtration Area [m²] 22 44 66 88 176 88 132 176 352
No. Control Heads [–]
1 1 1 1 2 1 1 1 1
No. of Segments per Disc [–] 20 20 20 20 20 30 30 30 30


Reliable Vacuum Filtration with Pan or Disc Filters.

For the aluminum industry, BOKELA provides several filter technologies. For seed and product filtration, BoVAC Disc and BoVac Pan are internationally renowned. BoHiBar Disc filter are a groundbreaking technology for dry bauxite residues.

Fertilizers Based on Potash

Low Maintenance and Quiet Filtration Solutions for Wet Processing of Potash.

In the fertilizer production, potash is an important substance. Wet processing requires filtration. Thanks to slow turning filter technologies, BoVac Pan and BoVac Disc provide noise-reduced and low-maintenance solutions.

Ore Processing

Strong filters for Modern, Improved Treatment Processes.

Getting the most put of everything you do – that’s the credo for ore processing. In order to achieve a high gain, filtration technologies have to meet certain demands. BOKELA provides solutions to filter very fine concentrates.

Coal Production

For More Economy and Environmental Safety in Coal Production.

Economy and environmental protection are essentials for modern and efficient coal preparation. BOKELA provides the right filter technologies for this endeavor. As an established expert of the industry, BOKELA sets its own standards.

Storing Tailings Eco-Friendly

Filter Technologies and Systems for Sustainable Processing.

The processing and storing of tailings from ore and mineral production often is quite the challenge. For a water-saving treatment and eco-friendly storing, one needs cost-efficient filter technologies.

Filtration of Zinc Tailings

Two BoVac Disc filters M176 are operated for dewatering of zinc tailings from a copper and zinc mine in Australia, Qld. Start of operation was in 2014.

Filtration of Copper/Gold Tailings for Mine Backfill

Two BoVac Disc filters L176 are operated in a Gold/Copper Mine in Bulgaria for the filtration of flotation tailings which are used for mine backfill. The dewatered and discharged filter cake is mixed with cement and pumped back to the underground to fill the galleries.

Filtration of Al-Hydrate (Fine Seed)

The two BoVac Disc filters L176 are operated in an Australian Alumina refinery for filtration of Al-hydrate fine seed before being recycled to the precipitation tanks.

Filtration of Flotation Coal Concentrate

The two BoVac Disc filters L176 with a filtration area of each 176 m² are used in a coal preparation plant in Australia for the filtration of flotation coal concentrate.

Vacuum Filtration. State-of-the-Art Design for High Performance.

BoVac Disc, BoVac Drum and BoVac Pan – those are continuously working disc, drum and pan filters for vacuum filtration. They are used especially with regard to continuous production processes with high throughputs.


Low residual moisture is important for the further processing of the filter cake. With mechanical drying, an intelligent filter design and the right operation mode, production costs can be considerably reduced.

Filter Cake Washing

Filter cake is the name for the solids filtered from a suspension and collected at the surface of the filter medium. The washing of the filter cake is essential to the purity of the filtered solids and thus, for the reusability.

Solid Separation

Solid separation is the first process step with regard to separating solids from fluids. The driving force behind the process is the pressure difference with which the suspension flows through the filter medium.

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