Abstract: Apparatus for crushing fragments of mineral material comprises a rotary crusher mounted above, and co-operating with, a scraper-chain conveyor. The rotary crusher has a cylindrical body provided with a plurality of first, second and third rows of chisels. The chisels are detachably mounted in holders fixed to the cylindrical body. The chisels are all the same, but the holders are of different sizes so that the chisels of a first set have a longer radial reach than the chisels of second set, which in turn have a longer radial reach than the chisels of a third set. Each first row has chisels of the first and second sets, and each of the second and third rows has chisels of the third set. The provision of the chisels of the first and second sets having longer radial reaches enables the mineral material to be drawn into the crushing gap between the rotary crusher and the scraper-chain conveyor and broken up more efficiently.

Abstract: Crushing apparatus employs a pair of rotatable crusher drums mounted to rotate about vertical axes to crush material such as mineral ore, fed through a gap between the drums by means such as scraper-chain conveyor. The drums are mounted on pivoting rocker arms which are adjustable to vary the crushing gap. The drums are hollow and are driven in opposite directions by hydraulic drive motors located inside the drums. Conveniently, the hydraulic motors have rotors connected to radial flanges inside the drums and stators fixed to the rocker arms.