VACUPRESS by Grenzebach

Posted in: , on 4. Sep. 2009 - 16:03



The VACUPRESS is an apparatus for deaerating and compacting/densifying fine-grained, light powders. Deaeration and densification are achieved by a combination of vacuum and mechanical pressure. The effect of the VACUPRESS process is generated by two drums, i.e. the filter drum and the pressure drum (see diagram, items 1 and 2), which rotate in opposite directions. The product to be treated enters the machine through a feed hopper and attaches to the filter drum (diagram, item 1). A vacuum is created inside the filter drum. As the drum revolves, the particles are rearranged and precompacted under the influence of the air passing through. The material treated in this way is then drawn into the clearance between the filter drum and the pressure drum (diagram, item 2) and subjected to a preselected rolling pressure. This causes the product particles to form an even denser arrangement and sometimes interlace but they will not agglomerate or be rigidly pressed together. At the end of the process cycle, the densified product is stripped off the filter drum and leaves the machine.

Design features

All VACUPRESS machines are made of corrosion-resistant silumin cast material. Parts coming into contact with the product are coated with two-component lacquer for additional protection. Special VACUPRESS versions made of stainless steel or featuring other coating systems can also be supplied. The body with top cover and the gear case are dust-tight. The filter drum and pressure drum are mounted in sturdy antifriction bearings. Sealing rings and slide discs at the pressure drum provide for sealing of the shaft. The filter drum (diagram, item 1) is connected to a vacuum line via a hollow shaft and packing box. The filter drum is covered with either a porous sinter metal or with a cloth, depending on the application of the machine. A flanged bearing housing with quick-release fasteners on the suction side provides for easy and fast replacement of the filter drum. The pressure drum (diagram, item 2), which has a smooth surface, is equipped with a device for infinitely variable adjustment of the clearance between the drums. A defined pressure is applied via the pressure drum either by means of spring assemblies or a separate hydraulic unit fitted to the adjusting device. Two knives (diagram, item 3) at the outlet of the machine strip the compacted material off the two drums. The VACUPRESS drums are driven via a variable-speed or frequency-controlled geared motor.


The VACUPRESS can handle product temperatures of up to approx. 100°C . Densification of the product is particularly gentle. Compared with conventional compactors or granulators, the pressing forces applied in the VACUPRESS are relatively low and thus have only a minimal impact on the characteristics of the products treated. The product flakes and slivers produced can be converted back to their original fine powdered state at any time without having to apply strong shearing forces. Some 800 VACUPRESS machines for a wide range of processes have been supplied since the mid 1950s. Reductions in volume of up to 75 % are achieved. Due their sturdy design and construction, VACUPRESS machines have very long service lives and require only very few spare parts. They can also be used for handing products involving an explosion risk.

Typical Applications

VACUPRESS machines are used for all dry, fine powdered bulk materials for which deaeration and densification is necessary or beneficial because of their low bulk weights. VACUPRESS machines serve as densifiers upstream from packaging systems (to reduce the shipping volume and dust formation and to improve the handling characteristics for the end user), as metering systems for better integration of materials into downstream process stages, or as precompactors in combination with granulators. The main applications today are in the processing of silicic acid, carbon black, pigments, aluminium hydoxide and magnesium hyoxide.

Limits of Application

VACUPRESS machines can be used wherever the bulk densities of very fine powders (finer than 40 micron) have to be increased because their great volume gives rise to high packageing, strorge and transportation costs or their high air content hinders further processing.

Powders emanating from production processes can be treated just as well as extremely finely ground powders.

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Re: Vacupress By Grenzebach

Posted on 20. Aug. 2010 - 10:35

Thank you Mr Holger Höck for this very intersting information about Vacupress GRENZEBACH BSH, I have the same equipement in my process fo granulation of silica( Alexanderwerck Rolls compactor), and I have a question about the size of the powder to be deaerated and densified before compaction:

You sayed " the The VACUPRESS is suitable for all fine powdered and dry bulk materials with [B][U][I]a maximum particle size of approx. 40 µm[B][U][I]"!!!

What's the scientific reason to explain that?

I mean if the particule size is upper than 40 µm what's happen!! Actually In my process the particules size is around 20µm and I want to granule powder around 200µm particules size, and after compacting and granulation to have granules around 1 to 2 mm paricules size!

Is this systme can work correctely with this kind of powder( 200 µm particules size)???if not what's the reason?? what's the the correlation of particules size and performence of the vacupress??? and why maxi 40 µm??.

Thank you for your help.


Changed Text By Bulk Online

Posted on 25. Aug. 2010 - 07:56

Dear Mr. Kilani

Thanks for your message.

Today I changed the text by Bulk-Online for the VACUPRESS Compactor.

Many thanks for your information, to correct the missprint in the text.

Did you got my first message (reply to your thread) ?

Have a nice day

Best regards

Holger Höck