Material treatment and apparatus

A particle treatment method for reducing particle size which includes the steps of introducing particles to be treated into an apparatus where there is a chamber with a substantially cylindrical portion and a rapidly rotating rotor coaxially positioned within the substantially cylindrical portion defining between the two a substantially co-annular cylindrical space, two or more blades spaced an equal distance apart around the circumference of the rotor and each extending from the rotor and defining a separation gap between an inner wall of the cylindrical portion and an outer edge or face of each of the respective blade, there being one or more vortex supporting and defining spaces between the respective blades, and at least some of the inner wall of the cylindrical portion having a friction inducing surface, and collecting the resultant treated particles.