Mill

A grinding mill has a rotating container (40) into which particulate material is fed. The container is rotated above critical speed to form a layer which is retained under high pressure against the container inner surface. Shearing discs (58) mounted inside the container induce shearing of the layer to promote particle fracture by shearing and abrasion in the pressurised layer. Fine ground material travels axially to the container discharge end (64). In one form of the invention, the container is rotated at sufficient speed to form a series of solidified zones (70) alternated with stirred zones (72) next to non-rotating shearing discs (58). These solidified zones act as solid discs rotating with the container.