Fine and ultra-fine screening of plaster and mortar

The basic component of any plaster is sand or fine-grained gravel with a grain size of up to 4 mm depending on the application. Binding material and water are added to ensure stability after drying. The specifications for the grain sizes vary as much as the aggregates themselves. That is why the technology used for precise screening should be considered separately for each application.

Finest separations with high-frequency vibration

Mineral plasters contain binding materials such as lime or hydrated lime, cement or Portland cement, gypsum, clay or combinations of these materials. Especially the very fine grain sizes have poor flow properties and are therefore difficult to screen through fine meshes. RHEWUM's directly excited screening machines generate high-frequency vibrations immediately at the screen cloth. This allows to fluidize finest powder, which is an important step on the way to the desired screening result.

Even at moderate capacities, the layer height on conventional vibrating screens increases to a multiple of the mesh size. It then becomes impossible to screen the fine material properly. The unique RHEWUM technology of directly excited, strongly inclined screening machines addresses this problem.

High transportation speeds on the screen lead to low layer height. High-frequency excitation of the screen mesh still guarantees sufficient comparisons between particles and mesh. This allows efficient classification of gypsum, cement and lime products even at 100 µm.

Moisture problems can be prevented by the specially developed RHEWUM mesh heating system which keeps the mesh free and prevents the grain from sticking to the mesh. Learn more about this technology here.

Continuous on-spec fines at highest throughput

Plaster is usually available in grain sizes of 2 mm, 3 mm and 4 mm. The limitations must be strictly observed to ensure trouble-free processing of the plaster on the construction site. However, quality should not be achieved at the expense of output.

If too much good grain is recycled to the crusher during screening, energy consumption, machine load and dust generation increase unnecessarily. This is where the RHEduo® screening machine proves its advantages. The double-frequency drive ensures high product output with fines free of off-spec grains. These machines enable separation efficiencies that cannot be achieved on most conventional vibrating screens.

Recommended screening machines for plaster and mortar



High performance magnetic drive directly at the screen mesh for efficient screening even at 100 µm

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Direct excitation of the screen cloth by low-maintenance unbalanced motors for fine separations

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Double-frequency drive for high product output with constant on-spec fines from 1 mm

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Product examples

  • Lime
  • Cement
  • Silicate
  • Gypsum
  • Mortar
  • Building adhesives/ tile adhesives

Your benefits

  • High-frequency vibration directly at the screen mesh fluidizes even the finest powder
  • No clogging of the screen cloth thanks to high conveying speed and automatic cleaning impulses
  • High separation quality without compromising capacity
  • Energy consumption, machine load and dust generation are significantly reduced