Method and impact crusher for reducing the size of mineral particles by impact

A method for reducing the size of mineral particles, comprising the steps of

• providing an impact crusher comprising a housing with therein provided a rotatable inner rotor having a central axis and a rotatable outer rotor provided coaxial with the inner rotor, the outer rotor comprising a circumferential wall having an impact section, wherein a discharge space is provided between the outer rotor and an inner surface of the housing;
• supplying mineral particles to the inner rotor while the inner and outer rotor counter-rotate around the central axis;
• displacing the mineral particles over the inner rotor under the influence of a centrifugal force and flinging of the displaced mineral particles from the inner rotor in a tangential direction towards the impact section of the outer rotor for reducing the size of the mineral particles upon impact, thereby obtaining impact reduced mineral particles, and
• discharging the impact-reduced mineral particles from the outer rotor to the discharge space,
• wherein the step of discharging the impact-reduced mineral particles comprises discharging the impact-reduced mineral particles from the outer rotor to the discharge space along opposite axial sides of the impact section of the circumferential wall.