The BoVac Drum filter with 1 m² filter area is operated in parallel to a 12 m² belt filter for filtration and washing of gypsum.

The gypsum is produced in a precipitation process by mixing lime with sulfuric acid, which has a pH of 4.5–7, a temperature of about 35 °C and an average particle size x₅₀ < 63 microns. The pre-thickened suspension is filtered at a solids content of 30–50% by weight. In order to increase production, the installation of a second band filter of the same size was considered. Laboratory tests and scale-up calculations showed, however, that a modern high-performance BoVac Drum filter with only 1 m² of filter surface handles this filtration task of 30 t/d gypsum

With only 1 m² filter area this BoVac Drum filter has a solids throughput of 40 t/d which is one third more than the daily solids performance of the 12 m² belt filter. The specific solids throughput of 1.660 kg/m²h is about 16 times more than the specific solids throughput of 105 kg/m²h of the parallel running belt filter.

Foot print of the BoVac Drum filter (4.2 m²) is six times less than foot print of the belt filter (24 m²). The filter is equipped with a cloth wash system and a bubble zone for on-line cloth cleaning.

Due to 24 exchangeable filter cells the change of filter cloth is unparalleld simple and quick. With a second set of filter cells already equipped with filter bags the time for re-clothing is only approx. 1-2 hours, including shutdown, cleaning and restart of the filter.