A 10 mm hydrocyclone was operated using a barite suspension with a maximum particle size of dmax = 7 μm. The test rig was equipped with a piston diaphragm pump for pressures up to 60 bar. At 40 bar and 20 °C, cut sizes d50 were obtained down to 0.7 μm; increasing the temperature to 50 °C resulted in d50 values down to 0.5 μm for a throughput of 0.6 m3/h. Another experiment was conducted at 40 bar using a batch hydrocyclone technology. Only the overflow was recirculated to the feed box, whereas the underflow was discharged via a collection box. Increasing the number of recirculations increased the separation of fines in the submicron range. The results showed that after 20 min particles with dmax = 1 μm were obtained in the hydrocyclone overflow. After 120 min, the particles size distribution had a dmax = 0.5 μm and a mean size of d50 = 0.2 μm. This procedure requires high energy consumption and is thus suitable only for fractionating small quantities of particles in the submicron range.
