thyssenkrupp Ring Hammer Mills – also known as Ring Granulators – are mainly used for crushing of coal in thermal power stations. The material is crushed initially by impact with ring ... Crusher Type of Ring Hammer Mill: RHM 1229 Rotor diameter x width: 1,220 mm x 2,900 mm Feed opening dimensions: 640 mm x 2,900 mm Speed: 750 rpm