Clear passage - Production of sharp-sized grades from naturally moist sands

The requirements of the premixed plaster industry for the production of up to five sharp-sized fractions mean dealing with various processes in order to meet the needs of this difficult to screen material. An Italian manufacturer of different grain sizes for well-known producers of premixed plasters approached RHEWUM with the objective of sizing 80 t/h crushed dolomite flour into the fractions 10.0 mm, 3.5 mm, 2.25 mm, 1.6 mm and 1.0 mm.

The mineral grades contained in premixed plaster are usually extracted at quarries and then crushed in a jaw crusher. After that the produced bulk materials are classified and made available for further production. The moisture of the feed material may vary widely due to rainfall and temperature changes and can be as high as 10 wt% – which makes screening difficult. Also, the concentration of the moisture in the fine fractions and the not inconsiderable clay content cause trouble in the processing.

On linear motion vibrating screens the indicated task led to immediate blinding of the...

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