Sand

For the production of sands for the construction materials industry BHS Sonthofen has developed special rotor crushers, which depending on crushing requirements and the application range of the sand product can process soft, medium-hard to hard and wear-intensive rock. At the company's test centre original machines are available for conducting test series. The following paper describes the principle of operation of BHS rotor crushers and presents different examples of crusher performance with reference to screening curves.

The preferred machines for the manufacturing of dry mortar sands are impact mills with a horizontal shaft, hammer mills and rotor impact mills with a vertical shaft. Impact mills can comminute feed material sized up to 120 mm and are therefore suitable for use as a primary crusher. However, they cannot process oversize particles up to 4 mm. Hammer mills with a bar grid produce a significantly higher portion of undersize material up to 0.1 mm (socalled ⌠filler) and should therefore only be used in applications where this is explicitly desired. Rotor impact mills can be used both as primary crushers for feed materials sized up to 56 mm and as secondary crushers for off-spec particle sizes up to4 mm.