Sand with maximum Grain Size of 300 µm

The Production of Sand for Use in Specialised Mortar Varieties

Sand with maximum Grain Size of 300 µm

The BHS rotor impact mills of type RPM are becoming more and more popular for the production of sand for dry mortar. In some countries they have become almost a standard for the production of extraordinarily fine sand.
(ed. wgeisler - 04/9/2017)
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The raw material is ground by crushing and shearing.

Sand is becoming a scarce product worldwide. today, even some desert region must purchase sand from other countries, that must mostly be shipped thousands of miles. The shortage of sand is so blatant that some countries have actually banned its export.

The reason for the shortage is the fact that the shape and size distribution of natural sand, which is found, for example, in desert sand, make it unsuitable as a building material. Furthermore, this sand also contains contaminants and must be extensively washed, treated and dried before utilisation, which drives the costs upwards.

The BHS rotor impact mill, frequently referred to in professional circles as the “Sandmaker”, will not solve the problem, but will alleviate it somewhat. It produces crushed sand with a cubical grain shape from rocks, which is very well suited as an additive for concrete or for the production of other building materials. The machines convert up to 70 tons of rock per hour into sand. 

The Rotor Impact Mills Type RPM 

The BHS rotor impact mill is a high-power crushing machine with a vertical shaft. The rotor is shaped like a ring and equipped with horseshoe-shaped hammers. This unique impeller rotor in combination with the toothed anvil ring achieves selective crushing and an outstanding grain shape. The mill is suitable for the crushing of all lightly to moderately abrasive minerals with a maximum feed material size of up to 56 mm (2 1/4 in). 

Intensive impact and shear crushing occurs between the horseshoe-shaped impact hammers and the toothed anvil ring. The machine can be adjusted to the user's requirements in an optimum manner using the rotor speed and the variable annular gap and will achieve a sand yield of up to 80%, depending on the hardness and grain size of the feed material.

The Function 

The feed material is fed into the machine from above using the central input nozzle. When it hits the rotor, it is accelerated outwards by the centrifugal forces, struck by the horseshoe-shaped impellers, and hurled against the anvil ring. Here, the crushing takes place by means of the impact and shearing effect. The material recoiling from the anvil ring hits the hammers again, where it is crushed by the repeat impact and slung back against the anvil ring.


The cover lid of the RPM can be swung aside for servicing and adjustments       

This process is repeated several times and causes the intensive, multiple strain on the feed material. The material leaves the rotor through the gap between the rotor and the anvil ring and falls downwards through the two discharge chutes.

The mill can be alternately operated with clockwise and counterclockwise rotation, which reduces the wear on the hammers.

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