Abstract: A method of crushing particles of material in a ball mill comprises feeding a mixture of balls and a charge comprising the particles to be crushed, a solvent and a lubricant continuously through a ball mill which initially contains balls. The balls are recovered from the mixture issuing from the mill and are re-introduced into the mill with a fresh charge. One form of apparatus for carrying out the method comprises a cylindrical container disposed with its axis horizontal and rotatable about said axis. The inlet and outlet of the mill are arranged centrally at opposite ends of the container, and the outlet leads to an annular sieve which rotates with and is coaxial with the container. The sieve retains the balls for return to the inlet and allows the milled charge to fall into a receptacle. In an alternative form of the apparatus, the container has inlets at both ends and has an outlet with an associated sieve at its mid-length.