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Sand with maximum grain size 300 µm

Published by
World Cement,

The BHS rotor impact mills of type RPM are becoming more and more popular for the production of sand for dry mortar. They have become the standard in certain countries for the production of extraordinarily fine sand.

The BHS rotor impact mills produce well graded sand in the proper shape with optimal grading curves which are exactly adapted to the "dry mortar" application. The good cubicity of the sand grains is crucial for enabling the mortar to be processed easily and for ensuring its good pumping capacity.

These properties have contributed to the fact that a large number of dry mortar plants worldwide are operated with BHS machines. One of the most important sales markets is Southeast Asia. Dry mortar in Southeast Asia is often not only used as plaster for outdoor and indoor surfaces or as masonry mortar or screed, but rather especially for fine finishing plasters. In contrast to Germany, coloured plasters are frequently used in Thailand, as are rough plasters, which have a particularly decorative structure and are coated without priming.

The requirements for the fineness of these products and thus for the properties of the sand are equally extraordinary. Particularly high-grade products are manufactured specially in Thailand, where sand having a grain size between 90 and 300 µm is used. A grain with a half millimetre diameter in Thailand is already considered a coarse grain.

Crushing the rocks and sifting out the oversized grains is not sufficient to achieve the specified grading curve. The crushed rock must instead be selectively broken down into fractions and then put back together into a precisely defined grading curve in accordance with prescribed formulas.

Rotor impact mills have particularly proven themselves here, since the properties of the discharged product can be precisely set by adjusting the circumferential speed of the rotor and the width of the annular gap. This makes it possible to produce sand with grading curves which precisely conform to the specification.

Twelve BHS rotor impact mills are currently operating on the premises of Thailand's leading dry mortar manufacturer, Siam Mortar, with ten more already having been delivered and set for commissioning in 2016. BHS delivered three additional machines for a project with another Thai manufacturer – also for dry mortar.

Moreover, Siam Mortar is operating four BHS VSI rotor centrifugal crushers of type RSMX for the crushing of granite – also for the production of dry mortar sand. In brief, more than 30 BHS machines are operating in the dry mortar industry in Thailand.

Philipp Parnitzke, BHS Area Sales Manager for Asia and the Pacific, explains the success in Thailand: "Our unique selling point is the fact that the rotor impact mills produce sand with cubical grain shape in finely graded fractions having precisely the grading curve required for dry mortar sand. It meets the requirements of our Thai customers exactly. Moreover, they can be serviced easily and quickly and exhibit little wear in proportion to their high production output."

The rotor impact mills from Sonthofen have become the standard in Thailand. This is proven, for example, by the fact that Siam Mortar awards contracts for new dry mortar plants to various plant constructors, but still uses the BHS rotor impact mills in every single project.

The crushing of the feed material can be selectively controlled by variation of the rotor's circumferential speed on the one hand, and by changing the gap width between the rotor and the anvil ring on the other hand. The impact hammers can be adjusted with just a few hand movements.

Adapted from press release by Joseph Green

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