Abstract: A grinder of solids or solids in liquids has a multiple milling stages. A rotating disc plate carries cutting elements on one side and hammer elements on another, both located at the circumference of the disc plate. The disc plate is rotated in a screened chamber to which the solids or the liquids containing solids to be ground are introduced. Ground product or slurry containing disintegrated solids is passed through the screen before discharged. The use of disc plate and milling elements reduces required torque, leading to improved energy efficiency and results in better performance of the grinder.