Agitator Bead Mills, Dry Grinding -- SpheRho from NETZSCH Premier Technologies LLC. NETZSCH SpheRho ®. The Agitator Bead Mill for finest Dry-Grinding. General. For the dry grinding of mineral and ceramic raw materials the agitator bead mill NETZSCH SpheRho ® impresses with very high product fineness and high throughput rates with low specific energy consumption.